BIOL 372 Exam 2

Each of the following statements about vertical transmission of parasites is correct except for one. What is the exception?
A. Vertical transmission across generations should favor relative benignity.
B. Sexually transmitted pathogens as a rule cause benign infections when they are transmitted to neonates?
C. Vertically transmitted pathogens are expected to evolve into mutualists if mutations cause them to no longer be transmitted horizontally.
D. Vectorborne pathogens tend to be more benign in mosquito vectors when they are more vertically transmitted
E. Microspordans tend to be more benign in mosquitoes when they are vertically transmitted

Which statement about “sit-and-wait” transmission is incorrect?
A. Sit-and-wait parasites are durable in the external environment and highly virulent.
B. Sit-and-wait parasites rely on the mobility of uninfected hosts to facilitate transmission.
C. Sit-and-wait pathogens cause hosts to be lethargic and thus to sit and wait for biological vectors to bite and transmit them
D. Mortality per infection is significantly correlated with sit-and-wait transmission for human bacteria and viruses that infect the respiratory tract.
E. An evolutionary perspective on sit-and-wait transmission helps to explains why the agents of smallpox, tuberculosis, and diphtheria are severe

Which of the following statements about parasites with complex life histories is incorrect?
A. The pattern of virulence in infections of predator relative to prey hosts is consistent for various groups of helminths (e.g., cestodes, nematodes, trematodes, and acanthocephalans)
B. Helminth parasites as a rule have a relatively low virulence in predator hosts
C. Helminth parasites as a rule have a relatively high virulence in prey hosts
D. Helminth parasites tend to be benign in definitive hosts whether or not the definitive hosts acquire the parasites through predation.
E. Complex life histories of protozoal parasites may involve predator-borne transmission.

Each of the following findings supports the idea that transmission by biological vectors favors evolutionary increases virulence, except one. Which one does not?
A. Yellow fever viruses that have cycled more extensively between humans and mosquitoes are more lethal in humans.
B. Plasmodium species that have cycled extensively between humans and mosquitoes are more severe in humans than Plasmodium species that have recently been transmitted to humans from simian hosts (i.e.,
from monkeys or apes).
C. Transmission of viroids, such as the Cdang Cdang viroid, by insect vectors explains most of the variation in viroid virulence.
D. Pathogens transmitted between humans by biting terrestrial arthropods are more lethal than pathogens that are directly transmitted between humans.
E. Vectorborne pathogens are generally less severe when they first enter humans than after they have been transmitted among humans for many cycles

Attendants are involved in transmission and probably in the evolution of virulence for each of the following categories of transmission except for one. What is the exception?
A. Waterborne diarrheal pathogens.
B. Microsporidan pathogens transmitted in water.
C. Hospital-acquired pathogens.
D. Viroids in agricultural settings.
E. Parvoviruses in kennels.

All of the following routes of transmission are associated with evolution of relatively benign disease except one. What is the exception?
A. Vectorborne transmission of viruses in their vector hosts.
B. Transmission of microsporidans from female mosquitoes to their eggs.
C. Transmission of viruses from female mosquitoes to their eggs.
D. Transmission of microsporidans among mosquito larvae.
E. Transmission of rhinoviruses in human populations

Each of the following suggests that the infrastructure of the United States protects us from severe pathogens except for one. Which one is the exception?
A. The rarity of hospital-acquired infections in the United States in recent decades.
B. The number of malaria infections arising from transmission within the United States relative to the number of imported cases.
C. The transmission of Shigella dysenteriae in Los Angeles during the early 1970s.
D. The association between screening of houses along the Tennessee River during the 1940s and malaria incidence.
E. The number of dengue infections arising from transmission within Texas relative to the number of infections that entered Texas across its border with Mexico.

What is the best explanation for the evolution of high virulence of parasitoids?
A. They are not really parasites but rather are predators
B. They have a mobile stage in their life cycle that allows their transmission to be independent of host mobility
C. They are poorly adapted to parasitism
D. Their hosts tend to be insects, which are inherently vulnerable to damage from parasites.
E. The death of their hosts results from suicidal behavior of the hosts rather than the negative effects of the parasitoids

What groups of organisms provide the most extensive set of host/parasite relationships confirming relatively high virulence of predator-borne parasites in prey hosts?
A. viroids
B. viruses
C. bacteria
D. helminths
E. parasitoids

Which of following statements offers the most reasonable explanation of Toxoplasma gondii's tendency to severely exploit rodents?
A. It is an adaptation to facilitate transmission to sandflies.
B. It is an adaptation to facilitate transmission to cats.
C. It is a side effect that occurs because rodents are not the natural host of T. gondii.
D. It is an adaptation that results from waterborne transmission of T. gondii.
E. It is an adaptation that results from vertical transmission of T. gondii in mosquitoes

Which of the following statements about Toxoplasma is incorrect?
A. Toxoplasma are protozoal parasites that are related to the protozoa that cause malaria.
B. T. gondii is transmitted by biting arthropods.
C. Cats are the definitive hosts of T. gondii.
D. T. gondii can cause birth defects and miscarriages in humans
E. T. gondii can cause dementia and death in immunocompromised adults

Which of the following best explains why malaria has not re-emerged in the United States.
A. Immigration control keeps people infected with Plasmodium from entering the US.
B. Our infrastructure strongly inhibits mosquito-borne transmission, and therefore keeps the generation of new infections below the break-even level.
C. Our health system effectively targets and cures incoming Plasmodium infection, preventing the spread of malaria.
D. The mosquito vectors for malaria no longer exist in the US.
E. The high nutritional status of people in the US gives them resistance to Plasmodium infection

According to the evolutionary theory of virulence, which of the following modes of transmission results in the most peaceful coexistence between host and parasite?
A. Vertical
B. vectorborne for the vertebrate host
C. sit-and-wait
D. attendant-borne
E. waterborne

What is the best evolutionary explanation for the great range of virulence found among viroid diseases of plants?
A. High virulence has been favored when attendants and their tools transmit viroids, whereas low virulence has been favored when transmission occurs via seeds and pollen.
B. The variation is attributable to variation in routes of transmission in natural settings
C. The high mutation rate of viroids is responsible for the high variation in virulence
D. The small genome size of viroids limits the ability of viroids to regulate virulence
E. The variation in virulence of viroids results from the broad variation in host species that the viroids infect in nature

Which of the following statements is an inaccurate characterization of the relationship between Shigella and waterborne transmission?
A. The most harmful species, Shigella dysenteriae, declines quickly relative to other Shigella species after protection of water supplies is first introduced.
B. Shigella flexneri predominates when improvement of water supplies has been substantial but is still incomplete.
C. The mildest species, Shigella sonnei, predominates after water supplies are completely protected.
D. The failure to control Shigella in poor countries can be important to rich countries, as evidenced by a major epidemic of Shigella dysenteriae that occurred in the United States when S. dysenteriae entered the United States from Mexico in the early 1970s and spread pervasively.
E. The association of Shigella virulence with improved water supplies occurs on local scales as well as regional scales

Which of the following interventions is not predicted by evolutionary considerations to result in evolution of reduced virulence?
A. purification of water supplies
B. making vaccines from virulence antigens
C. antibiotic treatment of ill patients when target pathogens are universally sensitive to the antibiotics
D. mosquito-proofing of houses and hospitals
E. using mild strains of the influenza virus in influenza vaccines

Which of the following statements about the evolution of virulence is not consistent with current theory?
A. Fitness benefits associated with virulence arise from conversion of host resources into pathogen propagation
B. Fitness benefits associated with virulence connect pathogen propagation with increased probability of infection per contact with susceptible individuals
C. Fitness costs associated with virulence arise when host illness reduces the frequency of contacting susceptible individuals
D. Fitness costs associated with virulence are influenced by modes of transmission.
E. The cost/benefit approach to virulence is an example of a valid conceptual framework that was introduced by medical experts before evolutionary biologists began making conceptual contributions to medicine

Which of the following generalizations about commensalism is incorrect?
A. Given enough time parasitisms would evolve inexorably to commensalisms.
B. Commensalism is defined as an interaction in which a symbiont neither harms nor benefits its host.
C. Commensalism represents a dividing line between parasitism and mutualism
D. The category of commensalism would virtually vanish if measurements of evolutionary fitness were sufficient to calculate net fitness effects with perfect accuracy.
E. Commensalism may be more useful as an abstract concept than as a category that encompasses numerous associations

Which of the following interventions does not rank among the most successfully interventions in the history of medicine (success being measured in terms of the number of lives saved) to control infectious disease
A. hygienic improvements that interfere with transmission
B. vaccination
C. use of antimicrobials that destroy or damage parasites inside of the host
D. application of genetic engineering and genomics to correct genetic load
E. recognition that disease can be caused by too much or too little of various noninfectious environmental factors, such as chemicals and radiation.

Evidence supports the idea that evolution toward benignity has played a role in control of all of the following pathogens except for one. What is the exception?
A. Control of Corynebacterium diphtheriae using the diphtheria toxoid vaccine
B. Control of Vibrio cholerae by water purification.
C. Control of smallpox by vaccination.
D. Control of Shigella species by water purification.
E. Control of Hemophilus influenzae by a vaccine based on a virulence antigen

Which of the following statements about cultural vectors is incorrect?
A. A cultural vector indicates the direction of a cultural change
B. A cultural vector can include an aspect of the physical environment
C. A cultural vector affects the evolution of virulence in a way that is analogous to the way in which a biological vector affects the evolution of virulence
D. A cultural vector is associated with increased virulence of diarrheal pathogens
E. A cultural vector is associated with the increased virulence of hospital-acquired pathogens

Each of the following parasites are often predator-borne, except for one. What is the exception?
A. Toxoplasma gondii
B. Microsporidans
C. Acanthocephalan worms
D. Trematode worms
E. Cestode worms

Which of the following statements about mosquito-proofing of dwellings is incorrect?
A. Mosquito-proofing of houses has been shown to eradicate malaria almost completely.
B. Mosquito-proofing of houses has been effective only since the introduction of pesticides, such as DDT, which are sprayed on screen doors to prevent mosquito infiltration.
C. Evolutionary theory predicts that mosquito-proofing of dwellings will favor evolution of reduced virulence of mosquito-borne pathogens such as Plasmodium falciparum.
D. Geographic variation in virulence of Plasmodium falciparum and Plasmodium vivax suggest that plasmodia have the capacity to evolve in response to mosquito-proofing of dwellings.
E. Dengue has entered the U.S. from Mexico, but has failed to spread probably because of mosquito-proof dwellings.

All of the following patterns of Shigella composition during the 20th century accord with the hypothesis that water purification would favor evolution toward benignity except for one. What is the exception?
A. The shift from Shigella dysenteriae to Shigella flexneri in the US.
B. The shift from Shigella flexneri to Shigella sonnei in the US
C. The continued presence of Shigella dysenteriae in Bangladesh throughout the 20th century.
D. The predominance of Shigella flexneri in Bangladesh throughout the 20th century.
E. The predominance of Shigella flexneri in the United Kingdom throughout the 20th century

Which of the following statements about the parasitism/mutualism continuum is incorrect?
A. Parasitism is a broad category that encompasses associations in which an individual (the parasite) lives in or on another individual (the host) and causes harm to the host.
B. Commensalism comprises about one third of the continuum, and encompasses associations in which an individual lives in or on another individual without harming or helping the host individual.
C. Mutualism is a broad category that encompasses associations in which both interacting individuals benefit.
D. Virulence is a measure of the harmfulness of an infection.
E. Pathogen virulence is a measure of the inherent harmfulness of an infectious organism

All of the following findings support the idea that the agents of malaria can evolve levels of virulence in response to environmental influences, except one. Which one does not?
A. Strains of Plasmodium vivax that generate high frequencies of hypnozooites tend to be regionally restricted and produce severe illness in which people fall into a trance-like state.
B. Plasmodium falciparum infections can be unusually mild just south of the Saharan desert.
C. Plasmodium falciparum and Plasmodium vivax tend to be mild where the presence of mosquitos is highly restricted seasonally.
D. Variation necessary for evolution toward low virulence already exists in local populations where P. falciparum is damaging
E. Plasmodium vivax strains endemic to northern latitudes (e.g., Korea) tend to be benign

Which of the following statements about the evolutionary control of disease is incorrect?
A. This way of controlling disease has been referred to as Virulence Management
B. This way of controlling disease makes use of evolutionary effects of interventions that provide reductions in the frequency of infections.
C. Evolutionary control of disease focuses on causing evolutionary reductions in the harmfulness per infection.
D. Evolutionary control of disease may involve hygienic improvements, vaccination or use of antibiotics.
E. Evolutionary control of disease is now being widely incorporated into disease prevention programs as evidenced by the reliance on introduction of vector-proof housing

Each of the statements about virulence of malaria is justified except for one. What is the exception?
A. Malaria is a specific example of the tendency for vectorborne disease that evolved higher virulence than most directly transmitted pathogens.
B. When vectorborne transmission opportunities are infrequent, pathogens should evolve mechanisms to become less virulent and persist inside their host.
C. The high virulence of malaria results largely from the fact that it was recently transmitted to humans from other primate hosts such as the chimpanzee, and has had insufficient time to evolve lower virulence.
D. The density of vectors dictates transmission opportunities for Plasmodium and is associated with elevated occurrence of parasitemia (parasites in the blood) in the wet seasons
E. High virulence of Plasmodium vivax occurs in areas with more continuous mosquito-borne transmission

Which of the following statements about persistence of sexually transmitted pathogens is incorrect?
a. Human papillomaviruses have evolved to be persistent by stimulating the replication of the cells they infect and by interfering with apoptosis
b. Hepatitis B viruses have evolved to be persistent by stimulating the replication of the cells they infect and by interfering with apoptosis
c. Human T-lymphotropic viruses (HTLVs) have evolved to be persistent by stimulating the replication of the cells they infect and by interfering with apoptosis
d. HIV has evolved to be persistent by stimulating the replication of the cells they infect and by interfering with apoptosis.
e. Human Herpes Simplex viruses have evolved to be persistent by remains dormant in the cell bodies of neurons,

Which of the following statements about immunological resistance and the evolution of virulence is incorrect?
a. Vaccination might favor evolution of increased virulence if vaccine strains are derived from benign strains because immunity generated from such a vaccine could select against benign strains.
b. Partial immunity from vaccination might favor “aggressive” strains that can break through the resistance especially in populations where natural resistance is low
c. Extremely high virulence in previously unexposed human populations (such as higher mortality of smallpox and measles in Native Americans upon first contact relative to Europeans) supports the idea highly levels of resistance can favor high levels of pathogen virulence.
d. where pathogens have been long present the strong immunological resistance generated by infections may favor “aggressive” strains to a much greater extent than vaccination.
e. Vaccination will as a rule favor increased virulence of the target organisms

Which of the following explanations about Toxoplasma gondii infections is incorrect?
a. In its natural cycle of transmission, Toxoplasma gondii is transmitted from rodents to cats by predation.
b. The best rule of thumb for controlling antimicrobial resistance in human T. gondii infections would be to use the best available anti-toxoplasmal drug in cats to prevent transmission to humans.
c. Toxoplasma gondii infects humans but is not transmitted from adult human to adult human
d. Restricting the use of particular anti-toxoplasmal antimicrobials to humans would help control the evolution of resistance to those antimicrobials in Toxoplasma gondii.
e. Prevention of T. gondii infection in humans would likely reduce the incidence of dementia, miscarriages, and birth defects.

Which of the following statements about antibiotic resistance is incorrect?
a. Staphylococcus aureus began evolving resistance to methicillin within a few years after methicillin was introduced.
b. If antibiotic resistance genes are present in a small percentage of S.aureus isolates in a hospital setting, extensive antibiotic use of antibiotics can lead to resistance in most isolates within a matter of weeks.
c. Although antibiotic resistance tends to evolve in hospital settings, hospitals are isolated from each other; transfer of resistant strains between hospitals is therefore negligible.
d. Resistance to vancomycin evolved gradually decades after it was introduced because it is a last resort antibiotic and therefore is used relatively infrequently.
e. Resistance of Pseudomonas aeruginosa to fluoroquinilones increased only gradually probably because P. aeruginosa is not readily transmissible from person to person

Each of the following statements about antibiotic resistance is correct except for one. What is the exception?
A. Cystic fibrosus is now readily controlled by antibiotic treatment because Pseudomonas aeruginosa, which is a major cause of damage in cystic fibrosus patients, has not been able to evolve resistance to fluoroquinolone antibiotics.
B. The selection pressure favoring increases in antibiotic resistance are particularly great in hospitals.
C. Historically, there was been a long lag between the introduction of vancomycin and the evolution of resistance to this drug probably ecause vancomycin was used less than other antibiotics because of
damaging side effects.
D. The evolution of resistance to Enterococcus worried epidemiologists because the genes for this resistance can be transferred to Staphylococcus aureus.
E. methicillin resistant Staphylococcus aureus (MRSA) is a big problem because it has evolved resistance to virtually all of the antibiotics that had previously been effective against Staphylococcus

Each of the following statements is a valid caveat about the evolution of antibiotic resistance except for one. What is the exception?
A. The intermixing of populations can increase the speed with which evolution of antibiotic resistance evolves.
B. The development of antibiotic resistance may depend on the extent to which people within the population have different antibiotic exposures (e.g., people in hospitals or outside of hospitals)
C. The evolution of antibiotic resistance is influenced by the extent to which antibiotic resistant strains can be transmitted between hosts relative to antibiotic sensitive strains.
D. Administration of antibiotics to a host can favor antibiotic resistance not only in the targeted organism but also in other organisms, which can then spread the resistance among different species of bacteria by transfer of plasmids.
E. The evolution of antibiotic resistance would not be a problem if patients always took the full regimen of antibiotics prescribed by their physicians

Which of the following is not an aspect of the biological problem of antibiotic resistance in Staphylococcus.
A. Within the hospital environment, antibiotic resistance of Staphylococcus aureus can evolve from presence in a small minority of isolates to a majority within two weeks of prophylactic antibiotic
treatment

B. One aspect of the problem is that antibiotic use in hospitals is high and travel between hospitals generates very large population of pathogens that can respond to this selective pressure.
C. Transport of antibiotic resistant Staphylococcus aureus between hospitals has been documented, along with spread among patients in the affected hospitals.
D. Control of Staphylococcus antibiotic resistance will become very difficult if it acquires resistance to vancomycin, although this has not yet happened.
E. Enterococcus has acquired resistance to vancomycin, and interspecific transfer of resistance genes between Enterococcous and Staphylococcus is possible

Which of the following is not an aspect of the sociological problem of antibiotic resistance?
A. Antibiotic resistance tends to evolve in people in lower socioeconomic strata because they see physicians less frequently.
B. Antibiotic usage is often good for the patient and the physician over the short term but bad for the society over the long term, because of the generation of antibiotic resistance.
C. Curtailing inappropriate use of antibiotics will not eliminate the selective pressure favoring antibiotic resistance.
D. If antibiotic resistant variants are not yet in the patient population, patients who do not take the full regimen of antibiotics may foster the ability of pathogens to evolve antibiotic resistance gradually from
low to high levels
E. If fully antibiotic resistant variants are already in the patient population, taking the full regimen of antibiotics may increase the rate at which evolve antibiotic resistance spreads through the population

Each of the following actions should in principle suppress the evolution of antibiotic resistance except for one. What is the exception?
A. Restricting the antibiotic in question to dead-end infections.
B. Restricting the use of antibiotics to the infections against which the antibiotic is effective.
C. Favoring the evolution of reduced virulence by protecting against water-borne transmission.
D. Prophylactic use of antibiotics in hospital wards.
E. Favoring the evolution of reduced virulence by using virulence antigen vaccines

Which of the following generalizations is not consistent with the characteristics of the cholera strains isolated from the epidemic in Latin America during the 1990s?
A. V. cholerae evolved to be more toxigenic and less sensitive to tetracycline in Ecuador where protection of water supplies was poor.
B. V. cholerae evolved to be less toxigenic and remained sensitive to tetracycline in Chile where water supplies tend to be well protected.
C. As in Uganda, resistance to tetracycline evolved rapidly throughout Latin America, necessitating a switch to second line antibiotics.
D. The toxigenicity of V. cholerae was positively associated with the degree of antibiotic resistance in Guatemala.
E. The results as a whole suggest that protection of water supplies can favor evolution of reduced virulence and thereby suppress the evolution of antibiotic resistance.

Which of the following statements about virulence and transmission is incorrect?
A. The virulence and transmissibility of malaria make it a dangerous threat for emergence in the United States.
B. Epidemiological analysis of dengue transmission in Texas suggests that it is unlikely to emerge pervasively in the US
C. The virulence and transmissibility of the smallpox virus make it a dangerous threat for emergence in the United States but a vaccine that has already been widely used could negate this threat.
D. Epidemiological analysis of s.d transmission in Los Angeles suggests that this bacterium is unlikely to emerge pervasively in the US
E. Epidemiological analyses of the influenza experience from the beginning of 1918 to the present suggest that fears of a reemergence of pandemic influenza in humans of the sort experienced during the latter half of 1918 have been grossly exaggerated

Which of the following is not a valid explanation for the evolution of antibiotic resistance in hospital environments?
A. Hospital acquired infections may get treated with antibiotics more often because antibiotics are readily available.
B. Hospital acquired pathogens may get treated more often because they have evolved to be more virulent and are therefore more apparent.
C. A high rate of mutations occur in microbes that inhabit hospital environments.
D. Patients in hospitals may have compromised defenses and are therefore more vulnerable to infection and are more likely to require antibiotic treatment.
E. Pathogens can be transmitted within and between hospitals for prolonged periods of time allowing for evolution in response to selective pressures that occur in hospitals

Which of the following statements is incorrect?
A. The transfer of resistance-encoding plasmids between bacterial species exacerbates the problem of antibiotic resistance.
B. Reducing the use of antibiotics would be broadly beneficial both at the population level and to the individual patient who is being treated.
C. There are pathogens for which we have few if any backup antibiotics to use if the pathogen evolves resistance the currently used antibiotics.
D. If resistant variants are already in the human population, patients taking their full regimen may facilitate the emergence of resistance in the population.
E. If the resistant variants are not already in the human population, patients taking their full regimen may retard the evolution of resistance in the population

Which of the following is not a valid characterization of changes in virulence and antibiotic resistance of Vibrio cholerae in Latin America during the 1990s.
A. The toxigenicity of V. cholerae declined in Chile where water supplies were well protected.
B. The toxigenicity of V. cholerae increased in Ecuador where water supplies were not well protected.
C. In Guatemala antibiotic resistance and virulence were not correlated, perhaps because the organisms arrived there late during the 1990s.

D. Antibiotic resistance began to increase in Ecuador during the late 1990s but not in Chile.
E. Increased virulence probably favored selection for increased antibiotic resistance because infections with virulent strains were more likely to be treated.

Which of the following statements is an incorrect generalization about the strategy of dead-ending?
A. Dead-ending refers to evolutionary reductions in virulence that result from the death of infected individuals
B. Dead-ending is a strategy that involves inhibiting the evolution of antibiotic resistance
C. Dead-ending involves using different antibiotics depending on whether infected hosts can transmit their infections to new hosts
D. Dead-ending is a strategy that can be used to control evolutionary responses to vaccines
E. Toxoplasma gondii and Borrelia burgdorferi are examples of organisms for which the concept of dead-ending is applicable

All of the following are valid findings that raise dangers posed by hospital acquired infections except for one. Which one is not a valid finding?
A. Transmission of vancomycin resistance from Enterococcous to Staphylococcus.
B. Long-distance transmission of antibiotic resistant Staphylococcus between hospitals.
C. The discovery that spread of antibiotic resistance within human populations will be prevented whenever all patients take their full regimen of antibiotics.
D. The documentation of vancomycin resistance in multiple antibiotic resistant Staphylococcus aureus over the past two decades in U.S. hospitals
E. Penicillin resistance increasing from low to high levels within two weeks after the onset of prophylactic penicillin treatment

Each of the following statements about antibiotic resistance is true except for one. What is the exception?
A. The development of antibiotic resistance can depend on the extent to which a population of pathogens is present within and outside of cells
B. If resistant variants are present in the population of microbes exposed to antibiotics, evolution of antibiotic resistance will occur more rapidly than if resistant variants are absent.
C. If populations of pathogens intermix, antibiotic resistant variants can be introduced into the population that has not been exposed to the antibiotic and can serve as a basis for rapid evolution of antibiotic resistance that population
D. Exposure to antibiotics can cause targeted organisms to respond by entering alternative life forms that are less vulnerable to the antibiotic
E. To avoid evolution of antibiotic resistance, it is best to use broad-spectrum antibiotics because they kill all of the organisms that could contribute to antibiotic resistance.

Which of the following statements about evolutionary effects of interventions is incorrect?

a. Blocking of waterborne transmission is predicted to favor evolutionary reductions in virulence of multiple species of diarrheal pathogens simultaneously.

b. Vector-proofing of dwellings is predicted to favor evolutionary reductions in virulence of multiple species of vector-borne pathogens simultaneously.

c. Blocking of attendant-borne transmission in hospitals is predicted to favor evolutionary reductions in virulence of multiple species of hospital-acquired pathogens simultaneously.

d. Having infrastructure that removes durable pathogens from sites of environmental contamination (e.g., disinfection or removal of contaminated air from rooms) is predicted to favor evolutionary reductions in virulence of multiple species of respiratory tract pathogens.

e. Vaccination with a single type of vaccine is expected to favor evolutionary reductions of multiple species of respiratory tract pathogens simultaneously.

All of the following statements are associated with the principle of virulence management control of antimicrobial resistance except for one. What is the exception?

A. Provisioning of uncontaminated water should favor evolutionary reductions in antimicrobial resistance of diarrheal pathogens.

B. Provisioning of vector-proof houses and hospitals should favor evolutionary reductions in antimicrobial resistance of vectorborne pathogens.

C. When target pathogens are uniformly sensitive to antibiotics, antibiotic treatment should accelerate the evolution of virulence because pathogens will respond to the suppressive effects of antibiotic treatment by increasing their exploitation of the host.

D. Virulence antigen vaccines should reduce the evolution of antibiotic resistance in target pathogens

E. Blocking attendant-borne transmission should favor reduced antibiotic resistance in hospital environments

Which of the following explanations about Toxoplasma gondii infections is incorrect?
a. In its natural cycle of transmission, Toxoplasma gondii is transmitted from rodents to cats by predation.
b. The best rule of thumb for controlling antimicrobial resistance in human T. gondii infections would be to use the best available anti-toxoplasmal drug in cats to prevent transmission to humans.
c. Toxoplasma gondii infects humans but is not transmitted from adult human to adult human
d. Restricting the use of particular anti-toxoplasmal antimicrobials to humans would help control the evolution of resistance to those antimicrobials in Toxoplasma gondii.
e. Prevention of T. gondii infection in humans would likely reduce the incidence of dementia, miscarriages, and birth defects

All but one of the following statements about Chlamydia trachomatis is correct. What is the incorrect statement?
a. C. trachomatis causes a severe disease, lymphogranuloma venereum, in tropical regions because its pathogenicity depends on humid, warm conditions.
b. C. trachomatis strains tend to cause lymphogranuloma venereum less in Senegal where the potential for sexual transmission is relatively low than in areas in West Africa with the potential for sexual transmission is greater.
c. C. trachomatis can cause ectopic pregnancy.
d. C. trachomatis can cause reactive arthritis.
e. C. trachomatis can cause persistent infections in part because antigens are relatively absent on its transmission stage

Which of the following is not a sexually transmitted pathogen (i.e., transmitted through genital contact)?
A. human immunodeficiency virus
B. cancer-causing serotypes of human papillomavirus
C. hepatitis B virus
D. dengue virus
E. Human T-lymphotropic virus (=Human T-cell Leukemia/Lymphoma Virus= HTLV)

All of the following chronic illnesses are known to result from sexually transmitted bacterial infections except for one. What is the exception?
A. Lymphogranuloma venereum
B. Reiter’s syndrome (i.e., reactive arthritis)
C. adult T-cell leukemia
D. Ectopic pregnancy
E. Chancroid

Each of the following bacteria are known to cause sexually transmitted disease except for one. What is the exception?
A. Donovania granulomatis
B. Neisseria meningitidis
C. Gardnerella vaginalis
D. Ureaplasma urealyticum
E. Mycoplasma hominis

Which of the following generalizations about sexually transmitted pathogens is incorrect?
A. Sexually transmitted pathogens tend to be benign during their acute phases of infection.
B. Sexually transmitted pathogens tend to be most damaging during chronic phases of infection.
C. Sexually transmitted pathogens tend to be well adapted to avoid destruction by the immune system.
D. Several sexually transmitted viruses are known to cause human cancer.
E. Infertility has been more strongly associated with sexually transmitted viruses than with sexually transmitted bacteria.

Which of the following is not well explained by ease of transmission from people who are immobilized by their illness?
A. the evolution of Plasmodium falciparum's high virulence
B. the evolution of Treponema palidum's high virulence
C. the evolution of the smallpox virus's high virulence
D. the evolution of V. cholerae's high virulence
E. the evolution of high virulence among hospital-acquired Escherichia coli.

For all of the following pathogens except one, studies have associated a higher virulence with a higher potential for sexual transmission. Which is the exception?
A. HTLV
B. Chlamydia trachomatis
C. HIV
D. Hepatitis B virus
E. Human papillomavirus

Which of the following viruses do not use activation of cellular replication as a mechanism for persistence within the host?
A. human papillomavirus
B. HTLV
C. Rhinoviruses
D. Hepatitis B virus
E. Epstein Barr Virus

One of these viruses does not generate all of the following alterations in their host cells: activation of cellular replication, blocking of apoptosis and immortalization of cells. Which virus does not generate these alterations?
A. Human papillomavirus
B. Human T Lymphotropic virus
C. Human immunodeficiency virus
D. Epstein Barr Virus
E. Hepatitis B virus

Which of the following statements about human papillomaviruses is incorrect?
A. Human papillomaviruses cause cervical cancer and penile cancer.
B. Human papillomaviruses cause venereal warts
C. Human papillomaviruses evolved increased virulence during the war that caused the disintegration of Yugoslavia
D. Sexually transmitted human papillomaviruses activate cellular replication and inhibit apoptosis.
E. The similarity in effects of HTLV-1 and human papillomaviruses on infected cells can be attributed to the fact that they are both retroviruses

Which of the following is not an acceptable explanation for the tendency of viruses to activate cellular replication, block apoptosis and "immortalize" infected cells?
A. These attributes were probably favored by natural selection to allow sexually transmitted viruses to be more effectively transmitted to new sexual partners.
B. The attributes are common side effects of viral infections in general because viruses tend to cause most cellular processes to be dysregulated.
C. These attributes allow sexually transmitted viruses to replicate and persist inside of people for long periods of time.
D. The attributes may allow viruses to replicate with little exposure to the immune system.
E. The inhibition of apoptosis negates a defense mechanism of the host to control infection.

All of the following comparisons showed an association between HIV virulence and the potential for sexual transmission except one. Which is the exception?
A. Comparison of times between onset of infection and AIDS among homosexual men infected in 1983 with those who were infected before 1980.
B. Comparison of T-cell decline in Thailand among people infected with subtype E and subtype B HIV-1
C. A comparison of mortality of HIV isolates from Thailand with isolates from Japan in two inbred lines of mice models.
D. Comparison of immune dysfunction among HIV-1 infected prostitutes with HIV-2 infected sex workers in Senegal.
E. Comparison of the HIV-1 subtypes that predominated in Senegal with those that predominated in other areas of West Africa

Which of the following is the best explanation for the association of lymphogranuloma venereum (LGV) with tropical regions
A. LGV occurs in many tropical regions because of a high potential for sexual transmission of Chlamydia trachomatis.
B. Populations in tropical regions tend to be less resistant genetically to Chlamydia trachomatis.
C. High temperature in the tropics favors the lesion formation that characterizes LGV.
D. Skin is more often exposed to infection in tropical regions, so rates of skin-to-skin transmission from lesions is more feasible.
E. High humidity in tropical environments favors the lesion formation that characterizes LGV

Which of the following points is not relevant to the prediction that sexually transmitted pathogens will eventually be newly recognized as causes of chronic diseases in the future?
A. Causes of disease are well understood for only about half of human diseases
B. Chronic manifestations of sexually transmitted diseases almost always are exploitations that increase transmission during the chronic phase
C. Almost all diseases of uncertain cause are chronic diseases
D. Sexually transmitted pathogens should evolve to cause persistent infections
E. Pathogens are more likely to cause chronic disease if they persist within a host than if they do not

Which of the following pieces of evidence is not relevant to the prediction that sexually transmitted pathogens will eventually be recognized as causes of a disproportionately large number of diseases that are not yet accepted as caused by infection?
A. A large portion of the chronic diseases for which infectious causation has recently been accepted are caused by sexually transmitted pathogens
B. Only about 20% of all known infectious diseases are caused by sexually transmitted pathogens
C. In contrast to pathogens transmitted by saliva, pathogens transmitted by genital contact are known to cause cancers and other chronic diseases .
D. Sexually transmitted pathogens are implicated (though not proven) as causes of chronic diseases of unknown cause
E. Sexually transmitted pathogens of humans generally have adaptations that allow them to persist for long periods of time within humans.

Which of the following geographic comparisons does not support the idea that a low potential for sexual favors low virulence of sexually transmitted pathogens?
A. The greater presence of lymphogranuloma-venereum-inducing variants of Chlamydia trachomatis in Senegal than in other parts of West Africa.
B. The greater prevalence of subtype A HIV-1 in Senegal relative to other areas of West Africa.
C. The prevalence of Treponema pallidum declined more rapidly than the prevalence of Chlamydia trachomatis, in response to increased condom use in Fukuoka, Japan.
D. The lower prevalence of HIV-1 relative to HIV-2 in western Africa relative to central Africa
E. The fact that HIV-1 did not displace HIV-2 in Senegal as it did in other West African countries.

All of the following points except one suggest that pathogens transmitted by kissing or sexual contact will eventually be recognized as disproportionately involved as causes of chronic diseases for which infectious causation is not yet accepted. What is the exception?
A. These pathogens tend to cause persistent infections.
B. This category of pathogens has been recognized disproportionately as common causes of chronic diseases over the past thirty years.
C. This category of pathogens is disproportionately represented among candidate causes of chronic diseases for which causation is still uncertain.
D. Kissing and sexual contact compromise immune defenses thereby increasing vulnerability to infections that are transmitted by these activities.
E. These pathogens often have mild acute phases which have made links between infection and illness difficult to demonstrate

All but one of the comparisons listed below support the hypothesis that a low potential for sexual transmission in Senegal favors evolution of sexually transmitted pathogens toward benignness. Which one does not?
A. A greater prevalence of HIV-1 subtype A in Senegal relative to most other West African countries.
B. A lower death rate from human herpes simplex virus type 2 strains from Senegal relative to those from Guinea Bissau in a mouse model for assaying virulence.
C. Greater persistence of HIV-2 relative to HIV-1 in Senegal than in other West African countries.
D. Preponderance of milder Chlamydia trachomatis in Senegal relative to other West African countries.
E. Greater prevalence of HIV-2 relative to HIV-1 in Senegal than in Central African countries

Which of the following statements about persistence of sexually transmitted pathogens is incorrect?
a. Human papillomaviruses have evolved to be persistent by stimulating the replication of the cells they infect and by interfering with apoptosis
b. Hepatitis B viruses have evolved to be persistent by stimulating the replication of the cells they infect and by interfering with apoptosis
c. Human T-lymphotropic viruses (HTLVs) have evolved to be persistent by stimulating the replication of the cells they infect and by interfering with apoptosis
d. HIV has evolved to be persistent by stimulating the replication of the cells they infect and by interfering with apoptosis.
e. Human Herpes Simplex viruses have evolved to be persistent by remaining dormant in the cell bodies of neurons,

A reduction in the potential for sexual transmission should have all of the following effects except one. What is the exception?
A. reduction in the prevalence of sexually transmitted diseases
B. reduction in the virulence of sexually transmitted diseases
C. an increase in the selective pressures favoring antibiotic resistance
D. reduction in harmful strains of sexually transmitted pathogens more than mild strains.
E. reduction in harmful species of sexually transmitted bacteria more than mild species.

Which of the following statements about the relationship between persistent infections and chronic disease is incorrect?
A. Some of the most devastating chronic diseases, such as cancers and cardiovascular disease, may be caused largely by persistent infections.
B. Mechanisms of persistence of human papillomaviruses nudge cells toward cancer by inhibiting apoptosis and facilitating replication of host cells.
C. The agent of Lyme disease, Borrelia burgdorferi is an example of a zoonotic pathogen that causes persistent infections in humans.
D. Sexually transmitted pathogens generally are persistent and cause more severe disease in their chronic phases than in their acute phases
E. Zoonoses are the greatest threat for causing persistent infections and hence chronic diseases, because their novelty makes them difficult for the human immune system to detect and control

For all of the following pathogens except one, disease is more severe in the chronic phase of infection. What is the exception?
A. Treponema pallidum
B. Human immunodeficiency virus
C. Human papillomavirus
D. Hepatitis B virus
E. Rhinovirus

What route of transmission is disproportionately implicated for the pathogens that are candidate causes of chronic diseases of uncertain cause?
A. biological vector-borne transmission
B. waterborne transmission
C. transmission by coughing and sneezing
D. sit-and-wait transmission (i.e., transmission via durable propagules)
E. sexual transmission

For which one of the following examples is host death best considered a “side effect”?
A. Death from tertiary syphilis
B. Death from kuru
C. Death of grasshoppers from Nosema acridophagus infections.
D. Suicidal death of honeybees from infections that could be spread to colony mates.
E. Death of Toxoplasma-infected mice as a result of being killed by cats

All of the following viruses except for one have mechanisms for persistence within a host by living within host cells. What is the exception?
A. Chlamydia trachomatis
B. Human papillomavirus
C. Vibrio cholerae
D. HTLV
E. Bordetella pertussis

Which of the following statements about the evolution of virulence is incorrect?
A. Scientists in microbiology and public health generally have recognized that infectious agents can evolve toward intermediate virulence or high level of virulence since the middle of the 20th century.
B. Considerations of transmission from immobile hosts offer general explanations for variation in virulence among acute infectious diseases.
C. Considerations of transmission from immobile hosts do not explain why sexually transmitted pathogens cause life-threatening disease.
D. Evolutionary considerations suggest interventions that should favor evolutionary control of pathogen virulence.
E. Evolutionary considerations suggest interventions that should favor evolutionary control of antibiotic resistance

Which of the following statements about virulence management is incorrect?
A. Virulence management refers to the control of disease by controlling of the evolution of virulence.
B. Virulence management is now a widely used component of public health policy.
C. According to the principals of virulence management, reductions in the potential for sexual transmission should simultaneously favor reductions in the virulence of the entire spectrum of sexually transmitted pathogens.
D. According to the principals of virulence management, introduction of vector-proof housing should simultaneously favor reductions in virulence across the entire spectrum of vectorborne pathogens, so long as the vector-proof housing inhibits transmission from severely ill individuals.
E. According to the principals of virulence management, protection of drinking water should simultaneously favor reductions in virulence across the entire spectrum of waterborne diarrheal pathogens.

Which of the following statements about needle-borne Plasmodium is incorrect?
a. Intentional transmission of Plasmodium has been used as therapy for syphilis
b. After being transferred by needle from human to human for over 100 consecutive transfers, Plasmodium knowlesi increased in virulence.
c. Plasmodium has not been unintentionally transmitted via needles in the United States.
d. The intentional transfer of Plasmodium during therapy has been associated with an increase in the number of parasites per mm3 of blood from about 1,000 to about 500,000.
e. Benign Plasmodium can evolve to cause lethal disease as a result of intentional needleborne transmission

Which generalization does not apply to needle-borne pathogens?
A. They can be transmitted by donated blood.
B. They can be transmitted by illegal drug use.
C. They can be transmitted by medicinal products such as clotting factor.
D. They often are sexually transmitted as well as needle-borne.
E. They are often waterborne as well as needle-borne

Which of the following statements about needle-borne pathogens is incorrect?
A. Malaria can be both mosquito-borne and needle-borne.
B. Neisseria gonorrheae can often be needle-borne or sexually transmitted.
C. Human Immunodeficiency Virus can often be needle-borne or sexually transmitted.
D. HBV can often be needle-borne or sexually transmitted.
E. Reduction of needle-borne transmission through needle exchange programs for drug addicts has been associated with milder HIV infections in New York and in Europe

Needle borne transmission has not been implicated for which one of the following pathogens?
A. HIV
B. influenza virus
C. Hepatitis C virus
D. Hepatitis B virus
E. Plasmodium species

Which of the following statements about therapeutic use of malaria is incorrect?
A. Prior to the discovery of effective antibiotics, injections of Plasmodium had been used to treat syphilis.
B. A big problem with using Plasmodium therapeutically was that it evolved increased virulence as it was sequentially transferred from patient to patient.
C. A big problem with using Plasmodium therapeutically is that control of parasitemia can be difficult.
D. A big problem with using Plasmodium therapeutically was that P. falciparum was used, and it is notorious for causing severe malaria.
E. Although malaria was presumed to be effective in controlling bacterial infections as a result of the fever it caused, other symptomatic effects of Plasmodium infection raise alternative explanations for its effectiveness

Which of the following does not support the hypothesis that needle-borne transmission may increase virulence?
A. Comparison of the HIV infections in Finland with those in the Netherlands
B. Faster progression to AIDS among Puerto Ricans than among Puerto Rican Americans living in New York City
C. Less virulent HIV infections where needle exchange programs have been enacted.
D. Increased rates of evolutionary change of HTLV-2 in drug users relative to non drug using native Americans.
E. Lower HIV virulence in Senegal than in the Ivory Coast

Which of the following statements about HTLV-2 infections is incorrect? ;
A. The distribution of HTLV-II indicates that it has been endemic in native Americans from the time of their arrival in North America over 10,000 years ago.
B. Historically, HTLV-II had been more benign than HTLV-I, presumably because HTLV-II had been transmitted in societies with infrequent opportunities of transmission, which would have favored mild variants.
C. HTLV-II became endemic in intravenous drug users a few decades ago.
D. Measurements of rates of genetic change indicate that HTLV-II has been replicating and evolving much more rapidly in intravenous drug users than in the historically endemic populations.
E. In non-drug-using, non-Amerindian populations, mortality is as low as among nondrug using native Americans

Which of the following generalizations about HTLV-II is incorrect?
A. Evolutionary theory of virulence predicts that HTLV-II will evolve increased virulence in intravenous drug users.
B. The geographic distribution of HTLV-II indicates that it was present in native Americans when they arrived in North America from Asia over 10,000 years ago.
C. HTLV-II causes the same spectrum of illness that is caused by HTLV-I, but is slightly more virulent.
D. For most of its evolutionary history in native Americans HTLV-II has apparently been cycling in mainly in small populations.
E. Measurements of rates of genetic change indicate that HTLV-II has been replicating and evolving much more rapidly in intravenous drug users than in the endemic groups

All of the following influences of needle-borne transmission may favor evolution of increased pathogen virulence except for one. What is the exception?
A. Needle-borne pathogens have high virulence mainly because there has been insufficient for them to evolve lower levels of virulence.
B. An immobile intravenous drug user might contaminate needles which then may be transferred to other users.
C. A high rate of needle-borne transmission could favor variants that reproduce explosively.
D. Improper sterilization of injection equipment by health personnel may lead to transfer of infections from very sick individuals
E. Needle exchange programs may contribute to reduced virulence even though critics argue the programs are condoning illegal intravenous drug use.

Which of the following statements about the current opioid and hepatitis C epidemics is incorrect?
A. Excessive marketing and distribution of the opioid Oxycontin by the Purdue pharmaceutical company for treatment of pain led to opioid addiction among hundreds of thousands of Americans
B. Restriction of access to Oxycontin led many of these individuals to shift to intravenous heroin and intravenous Fentanyl.
C. The surge in intravenous drug use of opioids has led to a massive rise in hepatitis C infections over the past decade and a corresponding rise in liver disease.
D. A rise in hepatitis C infections associated with the opioid epidemic occurred mainly among the “white” populations of low socioeconomic status but only slightly in other populations such as native Americans.
E. Evolutionary considerations suggest that the rise in Hepatitis C transmission may have been associated with an evolutionary increase in the virulence of HCV

Which one of the following statements about HTLV-II is incorrect?
A. The distribution of HTLV-II indicates that it has been endemic in native Americans from the time of their arrival in North America over 10,000 years ago.
B. Historically, HTLV-II had been more benign than HTLV-I, presumably because HTLV-II had been transmitted in societies with infrequent opportunities of transmission, which would have favored mild variants.
C. HTLV-II became endemic in intravenous drug users a few decades ago.
D. Measurements of rates of genetic change indicate that HTLV-II has been replicating and evolving much more rapidly in intravenous drug users than in the historically endemic populations.
E. In non-drug-using, non-Amerindian populations, mortality is as low as among nondrug using native Americans

If you rank the following interventions according to their historical importance in controlling disease in human populations, which intervention would be ranked at the bottom, as least important?
A. Compensation of the deficits arising from genetic mutations
B. Hygienic improvements
C. Treatment with anti-infectives such as antibiotics.
D. Vaccination
E. Interventions that prevent transmission of infectious agents (e.g., protection of water supply and screening of the blood supply)

All of the following viruses are known to be both needle-borne and sexually transmitted, except for one. Which is the exception?
A. Rhinoviruses
B. HIV
C. Hepatitis C virus
D. Hepatitis B virus
E. HTLV