Plagues and Pandemics

morbidity

degree of disease; how many people are affected

mortality

death

incidence

rise in the amount of infections; number of new cases in a particular location within a set time

prevalence

total number of cases with geolocation and time

modes of transportation

contact (direct or indirect), vehicle (airborne, waterborne, foodborne), vector (mechanical (insects) or biological (mites, lice))

endemic disease

regularly occurring within an area or community.

sporatic disease

a rare condition that occurs irregularly and infrequently in a population

epidemic disease

a widespread occurrence of a disease in a particular population within a specific time frame

pandemic

a widespread occurrence of an infectious disease over a whole country or the world at a particular time.

pathofenicity

ability to cause disease

virulence

the severity or harmfulness of a disease

defense virulence

allow microbes to escape destruction by the host immunity system (adhesins, capsules, antigenic variation)

offensive virulence

damage to the host (exoenzymes, exotoxins, endotoxins)

infective dose (ID)

minimum number of microbes necessary to cause infection

LD50

number of microbes needed to kill 50% of the animals infected

Severity of infection equation

severity (D) = dose (n)virulence (V)/ resistance (R)

how to name viruses

captilized genus them species

Types of pathogens

prions, viruses, prokaryotes (bacteria), fungi, algae, parasites, protozoa

prions

casues confirmation changes, makes it mutant, just protiens, no geneic material

mad cow disease

viruses defensive and offensive

defensive ( antigenic variation), offensive (lysis of host cells, large # of replication, inhbit host metabolism, damage to plasma membrane)

measles, mumps, rubella

prokaryotes (bacteria)

can be benefical but can cause disease

like the plague

adhesins virulence strategie

fixation to host cell surfaces

capsules virulence strategie

sugary surface to make it harder to detect, interfere with uptake of bacteria by the host immune system defenses (phagocytes)

defensive virulence factors

adhesins, capsules

offensive virulence stratigies

enzymes, exotoxins, endotxoins

enzymes virulence strategie

destroy intergrity of the tissue structure

exotoxins virulence strategie

specific activities that interfere with viral host functions

endotoxins virulence strategie

produce shocklike symptoms, chills, fever, weakness

Lipopolysaccharide (LPS)

endotoxin, releaaed from dead cells (cells disintegrates and anti-microbial drug killing), may trigger fever vasodilation, inflammation, shock, blood clotting

secreted virulence

extracellular enzymes, antiphagocytic factors (stop getting eaten), exotoxins ( several + specific to different types of bacteria)

exotoxins

are potent toxic proteins secreted by bacteria that have specific activities that interfere with host cell functions. They are often responsible for symptoms of diseases and can act at remote sites in the body. Unlike endotoxins, which are part of the bacterial cell wall and are released upon cell lysis, exotoxins can be part of the mechanism by which bacteria evade the immune system. Exotoxins can include various types such as neurotoxins (which affect nerve cells), enterotoxins (which affect the gastrointestinal tract), and cytotoxins (which damage host cells directly). Examples include the diphtheria toxin, botulinum toxin, and cholera toxin.

endotoxins

are components of the outer membrane of Gram-negative bacteria, primarily consisting of lipopolysaccharide (LPS). They are released into the surrounding environment when the bacterial cells are lysed or when they divide. Endotoxins trigger strong immune responses from the host, which can lead to a range of symptoms including fever, chills, weakness, and in severe cases, septic shock. Unlike exotoxins, which are secreted by living bacteria and have specific target effects, endotoxins generally affect the entire body and are not specific to particular cell types. The presence of endotoxins can activate the complement system and lead to inflammation, enhancing the immune response, but excessive release can overwhelm the system, leading to harmful effects.

fungi (eurkaryotic)

have membrane-bound nucleus + cell wall

algae

disease include shellfish poisoning, toxic algae blooms, caused by abuse to the enviroment or lack of balancde

what are protozoa (eukaryotes)

single-cell eukaryotes, very particular nutritional needs, cellular structure, motility, like freely in water

course of a microbial disease

susceptible, exposed, incubation/infected, symptomatic, recovered

mumps (name of pathogen, type of microorganism, vector/reservior, transmission, symptoms, body target, prevention, treatment

mumps

virus

spread through saliva or respiratory droplets/only found in humans

transmitted through direct contact with saliva or respiratory droplets from mouth, nose, or throat for up to 2 hours

painful swelling of salivary glands, fever, headache, muscle aches, fatigue, loss of appetite, earache, joint pain, testicular pain/swelling, ovaries pain/swelling, meningitis

parotid glands located in the cheeks and jaw

vaccination, handwashing, social distancing, boosters

can resolve on own, rest, hydration, pain relief, vaccination

measles (name of pathogen, type of microorganism, vector/reservior, transmission, symptoms, body target, prevention, treatment)

rubeola

virus

airborne/humans

by contact with infected nasal or throat secretions or breathing air that an infected person was in for up to 2 hours

high fever, a macular rash, Koplik’s spots which are small, blue-white spots surrounded by a bright red background on the linings of the orals cheeks, runny nose, red watery eyes, cough, the 3 c’s which are cough, corzya and conjunctivitis

targets respiratory tract

vaccination, PPE, hand washing

supportive care, apply lotion to rash, avoid bright light, rest, hydration, fever reducers, vitamin a, antibotics (for secondary infections)

bubonic plague (name of pathogen, type of microorganism, vector/reservior, transmission, symptoms, body target, prevention, treatment)

yersinia pestis

bacterium

fleas or rats/ rodents

through contact with infected rodents or fleas

flu-like, bubo that turn black in lymph nodes (swell, hemorhage under skin, turn black)

lymph nodes

removing brush, rock piles, junk, cluttered firewood, trash, limiting contact with rats, proper sanitation

antibotics

pneumonic plague: (name of pathogen, type of microorganism, vector/reservior, transmission, symptoms, body target, prevention, treatment)

yersinia pestis

bacterium

airborne droplets of those infected/ rodents + fleas

face-to-face contact when an infected person coughs or sneezes

fever, cough with bloody mucus, SOB, chest pain, weakness, headache, nasuea, vomiting

lungs

isolation, PPE, antibotics, hand hygiene, disinfection, survielance of symptoms

early use of antibotics

septicemic plague (name of pathogen, type of microorganism, vector/reservior, transmission, symptoms, body target, prevention, treatment)

yersinia pestis

bacterium

bite of inected flea, contaminated fluids, inhaling droplets/ wild rodents

through a bite of an infected flea or exposure to the bodily fluids of an infected animal

high fever, chills, extreme weakness, headache, muscle aches, shock, tachcardia, confusion, disorientation, nausea, vomiting, abdominal pain, bleeding into skin/nose/mouth, blackened skin

blood

reducing contact with infected rodents and fleas, proper sanitation practices

antibiotics

sylvatic plague

wild animal is infected and is bitten by a flea that absorbs bacterium and then bites a human spreading the plague

urban plague

from infected rodents that are bitten by fleas that absorb bacteria and then bite humans spreading the plague

what are the 3 stages of plague

bubonic, pnemonic, septcemic

rubella (name of pathogen, type of microorganism, vector/reservior, transmission, symptoms, body target, prevention, treatment)

rubella/ german measles
virus

droplet, direct contect, sharing food or drink/ humans

direct contact with nasal or throar secretion of infected person

rash, fever, diarrhea, sore throat, headache, joint pain, eye inflammation, enlarged lymph nodes

skin, lymph nodes, respiratory tract, brain

vaccination, PPE, hand washing, isolation

no specific treatment

mechanical + chemical barriers

skin, stomach acid, muscous membranes, cilla, lysozyme

what is nonspecific immunity

innate

what is specific immunity

adaptive

innate immunity

is the body's first line of defense against pathogens, characterized by non-specific responses that work immediately or within hours of an antigen's appearance in the body. It includes physical barriers like skin, mucous membranes, and chemical barriers such as stomach acid and enzymes found in saliva and tears. Key components of innate immunity also include immune cells like phagocytes (macrophages and neutrophils), natural killer (NK) cells, and various proteins that are part of the complement system. Unlike adaptive immunity, innate immunity does not provide lasting or specific protection against individual pathogens but plays a critical role in activating the adaptive immune response.

adaptive immunity

is a specialized immune response that develops over time after exposure to specific pathogens. It is characterized by the ability to recognize and remember specific antigens, and it provides long-lasting protection against previously encountered pathogens. Adaptive immunity involves the activation of lymphocytes, specifically T cells and B cells. T cells aid in directly attacking infected cells and coordinating the immune response, while B cells produce antibodies that target and neutralize pathogens. This system has memory cells that remain in the body long after the initial infection, allowing for a more rapid and effective response upon subsequent exposures to the same pathogen.

passive immunization

involves the transfer of actively produced antibodies from one individual to another, providing immediate, short-term protection against specific infections. This method is often used in situations where immediate immunity is necessary, such as with newborns receiving maternal antibodies through breast milk or when individuals are exposed to a pathogen and require prompt treatment. Passive immunity does not result in long-lasting immunity, as the transferred antibodies will eventually degrade, typically within weeks to months, and does not stimulate the recipient's immune system to produce its own antibodies.

active immunizations

is a process that induces the body to produce its own antibodies against a specific pathogen through exposure to antigens. This can occur naturally through infection by a pathogen or artificially through vaccination. The vaccines contain weakened or killed forms of the pathogen or pieces of it, which stimulate the immune system to recognize and remember the antigen. This leads to the generation of memory cells that provide long-lasting immunity, allowing the immune system to mount a rapid and effective response upon subsequent exposures to the same pathogen. Active immunization can result in lifelong protection and is a key strategy in preventing infectious diseases.

vaccine types

attenuated, inactivated, subunit/recomboinant, nucleic acis

attenuated vaccines

modified live

replicating microbes which stimulate strong immune response

herd immunity

dangerous to pregnant women, mutation can occur to make vaccine microbes virulent, higher rate of reactogenicity

inactivated vaccines

deactivated (whole microbes) or subunit (Ag fragments of microbes with rDNA)

killed microbes through heat or chemicals

cannot replicate/mutate into virulent form

stimulate Ab-mediated immunity

need booster shots

causes weaker immune response

adjuvant

makes vaccine work better

toxoid vaccines

chemical or heat modified toxins

stimulate Ab-mediated immunity

require multiple doses

recombinant DNA-vaccines

virulence gene is cloned into a nonvirulent microbe

DNA-vaccine

virulence gene is cloned into a plasmid which expresses foregin gene inside cells of the recipient

mRNA vaccine

mRNA protected in lipid nanoparticle delivered into muscles

vaccine safety

mild reactifencicty, anaphylatic shock, residual virulence, antibody(Ab)-dependant enhancment,

MMR vaccine effectiveness

measles,mumps, rubella

live attenuated vaccine

allows for irradication

1. To what complications from measles are the undernourished children especially susceptible

Undernourished children are especially susceptible to high fever, a macular rash, and Koplik spot which can be found on the inside of the cheeks of the mouth (buccal mucosa) from a measles infection. (Anderson, 2020)

1. How is the measles virus transmitted? 

The measles virus is transmitted through contact with an infected person's nasal or throat secretions or breathing the air. This is an airborne virus. It has the capability of remaining in the air and on surfaces for up to two hours. This created an extremely contagious virus for those who are unvaccinated.

1. How is measles diagnosed?

disease's characteristics. Health care providers will look for a high fever, a macular rash, Koplik’s spots which are small, blue-white spots surrounded by a bright red background on the linings of the orals cheeks. Vaccine status will also be asked and if one has traveled outside of the United States.

1. What are the physical characteristics of the measles virus?

single stranded RNA that has a large spherical envelope. There are six structural proteins. The virus is genetically stable. It is susceptible to heat at 122 degrees Fahrenheit. The virus is small enough to remain in the air for an extended period of time allowing for easy transmission. It can survive freeze drying and cold storage for decades. It can also replicate quickly once inside the host cell. (Demmler-Harrison, 2009) The infection dose is very small making transmission very easy as it can remain airborne for long periods of time.

1. Why is a measles outbreak of significant concern in a mass refugee setting?

due to how highly contagious it is. It is also unlikely that the refugees had access to adequate healthcare and are not vaccinated. With the virus ability to remain in the air and on surfaces for several hours after an infected person leaves makes packed areas very dangerous for transmission. The virus will spread quickly leading to a crisis with a refugee camp and overrunning the already very limited resources. 

How would you prioritize the expenditure of funds and resources in order to minimize the number of deaths caused by measles and other vaccine-preventable diseases?

I would prioritize the funds to providing vaccines to the refugees. These can help them have the resistance to these diseases and limit the number of deaths. Once the person is vaccinated they are much less likely to contract the virus which can control an outbreak. I would also allocate funds for sanitary and personal protective equipment to make sure the areas lived in a clean and have ways to protect themselves from transmission.

1. What is herd immunity?

enough people in a large group or area have gained immunity against a virus or other infectious disease. It can be achieved through natural infection, passive transfer or vaccination

1. Does herd immunity protect everyone from disease? Why or why not?

does protect everyone from the disease. This means those who have not caught it or can not be vaccinated for it. This only covers the certain variants that are being spread at the time.

1. How is mumps normally prevented?

normally prevented through the MMR vaccination. 

1. What serious complications can occur with mumps?

include inflammation of testes, ovaries, pancreas, brain, meningitis and loss of hearing. The inflammation of the testicles could lead to decreased fertility or temporary sterility. (CDC, 2025) It can also cause arthritis, deafness, pancreatitis and thyroiditis. (Cleveland Clinic, 2024)

1. What are the physical characteristics of the mumps virus?

caused by the paramyxovirus which is a member of the Rubulavirus family. It is a single-stranded, negative-sense RNA

1. Are individuals with the mumps infectious before signs and symptoms appear?

contagious before signs and symptoms appear. This occurs often which contributes to how infectious the virus is. (

1. How long after the onset of parotitis does an individual with mumps remain infectious?

contagious after the onset of parotitis for up to 5 days

1. How does the mumps virus cause disease?

virus replicates in the respiratory tract and in the salivary glands which allow it to spread to other parts of the body

1. What is the efficacy of the mumps vaccination?

88% effective

1. What type of epidemic curve is shown in the figure for mumps?

propagated outbreak.

1. How is the rubella virus transmitted?

transmitted when an infected person coughs or sneezes. It can remain in the air and hard surfaces for up to 2 hours after the infected person leaves the room

1. What are the clinical features of rubella?

fine, pink rash that appears in the face, trunk, arms, and legs. There is a mild fever, headache, runny nose, red/itchy eyes, enlarged  and tender lymph nodes, and aching joints.

1. How do the clinical features of rubella differ from those of measles (rubeola)?

seen as a less severe illness that starts with a fine, pink rash on the face and travels down the body that could be itchy. Measles appears as flat spots that are usually red or deeper pink. It usually starts out small and becomes larger. After healing the skin may turn brown and flake.

1. Describe the pathogenesis of rubella as adults.

disease is transmitted via coming in direct contact or droplet contact with the respiratory secretions of an infected individual. The virus multiplies inside the respiratory system and spreads to target organs.

1. What property of the rubella virus makes it particularly dangerous to pregnant women?

virus can cause congenital rubella syndrome for those who were not vaccinated before pregnancy. The syndrome is not curable and can cause a multitude of birth defect

1. In order to minimize the number of cases of the rubella disease, how would you manage the outbreak? 

minimize the outbreak vaccinations should be offered for those who are thinking of getting pregnant and boosters should be offered for those who are adults. I would also test all patients when outbreak is occuring to try to minimize contact with other patients. Masks should be worn in the office to stop the airborne aspect. 

what is the plagues virulence factor?

plague, caused by the bacterium Yersinia pestis, includes several mechanisms that enable it to evade the host's immune system and cause disease. Notably, Yersinia pestis has a type III secretion system that injects specific proteins into host cells, allowing the bacterium to manipulate macrophages and avoid destruction. Additionally, it produces a capsule that helps it resist phagocytosis by immune cells. Its ability to survive and multiply within the host, along with the production of toxins that disrupt the immune response, further enhances its virulence. These adaptations contribute significantly to the severity of infections, enabling the organism to spread effectively within populations.

what is the mumps virulence factor?

virulence is attributed to its ability to replicate in respiratory and salivary glands, avoiding immune detection and spreading throughout the body.

what is the measles virulence factor?

ability to replicate in respiratory and salivary glands, evade immune detection, and spread throughout the body.

what is the rubella virulence factor?

ability to spread to target organs after replication in the respiratory system.

what serious complications come from the plague

include septicemia, pneumonia, and potential death due to organ failure and shock.

what serious complications come from rubella

congenital rubella syndrome, which causes severe birth defects, as well as arthritis and encephalitis in adults. Infection during pregnancy can lead to miscarriage and serious fetal damage.

what serious complications can come from mumps

inflammation of testes, ovaries, pancreas, brain, meningitis, and potential loss of hearing. Inflammatory conditions can lead to decreased fertility or temporary sterility.

what serious complication can measles cause

pneumonia, encephalitis, and subacute sclerosing panencephalitis (SSPE), which can lead to long-term neurological issues and death.

what factors interfere with our global prevention efforts

insufficient resources, lack of access to vaccines, public misinformation, and socioeconomic barriers that affect healthcare delivery and education.

how anti-microbial drugs work

inhibit microbial growth or kill pathogens.

factors that promote healthcare acquired infections

1. Invasive Procedures: Use of catheters, ventilators, and surgical instruments increases the risk of infection. 2. Antibiotic Overuse: Overuse of antibiotics can lead to resistant strains of bacteria, making infections harder to treat. 3. Immunocompromised Patients: Patients with weakened immune systems due to illness or treatment (e.g., chemotherapy) are more susceptible to infections. 4. Poor Hand Hygiene: Inadequate handwashing by healthcare workers can facilitate the transfer of pathogens. 5. Contaminated Equipment: Medical devices that are not properly sterilized can transmit infections. 6. Environmental Factors: Unclean healthcare environments, including shared spaces and improper waste disposal, can harbor pathogens. 7. Staffing Levels: Insufficient staff can lead to rushed procedures and lapses in infection control protocols. 8. Patient-Centered Factors: Certain demographics (e.g., age, chronic illnesses) can also increase a patient’s susceptibility to HAIs. Effective infection control measures and adherence to hygiene protocols are crucial in minimizing these risks.

propagated outbreak

there is no common source because the outbreak spreads from person-to-person. The graph will assume the classic epi curve shape of progressively taller peaks, each being one incubation period apart.

epidemic curve, or “epi curve

is a visual display of the onset of illness among cases associated with an outbreak

what does the x-axis mean in epi-curve

date or time of illness onset among cases.

what does the y-axis mean in epi-curve

number of cases.

point source outbreak

persons are exposed over a brief time to the same source, such as a single meal or an event. The number of cases rises rapidly to a peak and falls gradually. The majority of cases occur within one incubation period of the disease.