Micro Exam 3 Diseases

COVID-19

causative agent: SARS-CoV-2 (coronavirus)

Transmission: droplet, airborne

virulence: spike proteins attachment to ACE-2 receptors; induction of autoimmunity

Symptoms: cytokine storm, respiratory illness, systemic and neurotrophic effects

prevention- masks, distancing, hygiene, and vaccines: pfizer & moderna, johnson & johnson

treatment- antivirals (paxlovid)

Endocarditis

inflammation of heart lining

risk factors: damaged valves, prosthetic valves, vascular trauma

acute symptoms: fever, anemia, irregular heartbeat, SOB, Janeway lesions, Osler nodes

Subacute symptoms: slower onset, enlarged spleen, clubbing of fingers/toes

Sepsis

microorganisms multiplying in bloodstream

symptoms: fever, mental changes, chills, rapid breathing, hypotension, GI symptoms

causative agent: bacteria or fungi

transmission: parenteral, endogenous transfer

virulence: cell wall or membrane components

blood culture

treatment: broad spectrum antibiotic until identification tested

Endotoxic Shock

• gram negative endotoxin release

• cytokine storm: hyperinflammation

• severe blood pressure drop

Plague (Yersinia pestis)

Forms:

1. pneumonic- respiratory

2. bubonic- lymph node swelling (bubo)

3. septicemic- bloodstream infection

30-50% treated

causative agent: Yersinia pestis

transmission: biological vector (flea), droplet contact (pneumonic), and direct contact w/ body fluids

virulence: capsule, plasminogen activator

culture: rapid genomic methods

prevention: flea/animal control; vaccine available for high risk ppl

treatment: streptomycin or ciprofloxacin

Tularemia

agent: francisella tularensis

• gram negative intracellular bacterium

• infective dose: 10-50 organisms

• Category A bioterrorism agent

reservoirs: rabbits, rodents, wild animals

symptoms: fever, weakness, ulcers, swollen lymph nodes

transmission: biological vector (tick), direct contact w/ body fluids from infected animal; airborne

virulence: intracellular growth

culture: serology most often used

treatment: gentamicin or streptomycin

Lyme Disease

Agent: Borrelia burgdorferi (spirochete)

features: antigenic variation, tick transmitted

disease progression:

1. bull’s eye rash

2. fever/headache

3. cardiac & neurological issues

4. polyarthritis

transmission: biological vector (tick)

virulence: antigenic shifting, adhesins

culture: acute/convalescent sera testing

treatment: doxycycline adn /or amoxicillin, cephalosporins and penicillin

Infectious Mononucleosis

agent: Epstein- Barr virus (EBV)

• herpesvirus

• integrates into host DNA

• Latency enables immune evasion

• 90% population infected

transmission: direct, indirect contact; parenteral

virulence: latency, ability to incorporate into host DNA

culture:differential blood count

treatment: supportive

lifelong persistence

Anthrax

agent: bacillus anthracis

• gram positive spore former

Toxin components:

• edema factor

• protective antigen

• lethal factor

Forms: cutaneous, pulmonary, GI, CNS (meningitis)

transmission: vehicle (air, soil, food), indirect contact (animal hides)

virulence: triple exotoxin

culture: direct fluorescent antibody tests

prevention: vaccine used in combo with antibiotics

treatment: in consultation with the CDC

Hemorrhagic Fevers

• rupture blood vessel; bleeding

Characteristics: RNA enveloped viruses, high fever and internal bleeding, often mosquito borne

examples: yellow fever, dengue, chikungunya, ebola, marburg, Lassa fever

reservoirs: mosquitos or bats/rodents

Non Hemorrhagic Fevers

high fever without bleeding

causes: mostly bacteria and one protozoan

examples: brucellosis, Q fever, cat-scratch disease, Trench fever, Ehrlichiosis, Anaplasmosis, spotted fever rickettsiosis

Brucellosis

• non hemorrhagic fever

• causative agent: Brucella spp.

• virulence: intracellular growth; avoidance of destruction by phagocytes

• undulating fever pattern

transmission: direct contact, airborne, parenteral (needlesticks)

culture: gram stain of biopsy material; PCR

prevention: animal control, pasteurization of milk

treatment: doxycycline plus gentamicin or streptomycin

• undulating fever, muscle aches

Q Fever

• non hemorrhagic fever

• agent: Coxiella burnetii

• animal contact transmission

• tick cycle among animals

transmission: airborne, direct contact, food-borne

virulence: endospore like structure

culture: serological tests for antibody; PCR

prevention: vaccine for high risk population

treatment: tetracycline or TMP/SMZ

• airborne route of transmission, variable disease presentation

Cat-Scratch Disease

• agent: Bartonella henselae

• cat scratches/bites

• swollen lymph nodes

• non hemorrhagic fever

transmission: parenteral (cat scratch or bite)

virulence: endotoxin

culture/diagnosis: biopsy of lymph nodes plus gram staining; ELISA

prevention: clean wound sites

treatment: Azithromycin or rifampin

Trench Fever

• agent: Bartonella quintana

• transmision: spread by lice (biological vector)

• endocarditis possible

• 5 day fever

• nonhemorrhagic fever

virulence: endotoxin

culture: ELISA

prevention: avoid lice

treatment: Azithromycin and doxycycline

Ehrlichiosis (southeast south central US)

• transmission: tick borne intracellular bacteria

• fever, headache, muscle pain

• agent: Ehrlichia species

• nonhemorrhagic

culture: PCR, indirect antibody test

prevention: avoid ticks

treatment: doxycycline

Babesiosis

• protozoan infecting RBCs

• tick transmitted

• requires antiparasitic therapy

• nonhemorrhagic fever

• agent: Babesia species

culture: blood smear

treatment: combination therapy with antibacterial and antiprotozoal

• northeastern and upper midwestern united states

Rocky Mountain Spotted Fever

• agent: rickettsia rickettsii

• tick transmitted

• rash after fever

• cardiovascular damage

• high mortality untreated

• nonhemorrhagic fever

virulence: induces apoptosis in cells lining blood vessels

culture/diagnosis: fluorescent antibody, PCR

treatment: doxycycline

• most severe of the rickettsioses

Chagas Disease

• agent: trypanosoma cruzi

• symptoms: acute fever & swelling, chronic heart & GI damage

• non hemorragic fever

transmission: biological vector (triatomine bug), vertical

virulence: antioxidant enzymes, co-opting host antigens; induces autoimmunity

culture/diagnosis: blood smear in acute phase; serologicla methods in later stages

prevention: insect control

treatment: consult CDC

• considered a neglected parasitic infection (NPI)

Malaria

agent: Plasmodium spp.

• different species

• asexual phase- humans

• sexual phase- mosquitoes

• symptoms: chills, fever, sweating

• severe complications: cerebral malaria, anemia, organ enlargement

• prevention: nets and repellents, chemoprophylaxis (antibiotics/antivirals), vaccination

transmission: biological vector (mosquito), vertical

virulence: multiple life stages; multiple antigenic types, ability to scavenge glucose, GPI toxin, cytoadherence

culture/diagnosis: blood smear; serological methods

treatment: Artemisinin, combination therapy; consult WHO

Human Immunodeficiency Virus 1 or 2 (HIV)

characteristics:

• retrovirus

• uses reverse transcriptase

• integrates into host genome

Types:

• HIV 1 (dominant)

• HIV 2

Symptoms:

• weight loss

• immune collapse

• kaposi sarcoma

• opportunistic infections

Transmission: direct contact (sexual), parenteral (blood-borne), vertical (perinatal and via breast milk)

• blood contact

• sexual transmission

• breast milk

• needles

virulence: attachment, syncytia formation, reverse transcriptase. high mutation rate

culture/diagnosis: immunoassay to detect antibodies as well as HIV antigen

Diagnosis:

• antibody testing

Prevention:

• barrier protection

• antiretroviral therapy

Treatment: aantiretroviral regimen

-three drug regimen:

• two nucleoside RT inhibitors

• one non-nucleoside RT inhibitor

Antibiotics Targeting Gene Expression- inhibit protein synthesis

• Rifamycins

• Actinomycin D

Antibiotics Targeting Gene Expression- interfere w/ ribosome

• Erythromycin

• Spectinomycin

Yellow Fever

• hemorrhagic fever

• causative agent: yellow fever virus

• transmission: biological vector (Ades mosquito)

• virulence: disruption of clotting factors

• prevention: live attenuated vaccine available

• culture: ELISA/PCR

• treatment: supportive

• accompanied by jaundice

Dengue Fever

• hemorrhagic fever

• biological vector (Aedes mosquito)

• virulence: disruption of clotting factors

• culture/diagnosis: Rise in IgM titers

• prevention: new vaccine approved in 2019

• treatment: supportive

• “breakbone fever”

Chikungunya

• hemorrhagic fever

• agent:Chikungunya virus

• transmission: biological vector: Aedes mosquito

• virulence: disruption of clotting factors

• culture: PCR

• treatment: supportive

• arthritic symptoms

Ebola and/or Marburg

Causative agent: ebola virus, marburg virus

transmission: direct contact, body fluids

virulence: disruption of clotting factors

culture: PCR, viral culture

• new ebola vaccine tested in 2016

• massive hemorrhage, rash sometimes present

Lassa Fever

causative agent: Lassa Fever virus

transmission: droplet contact (aerosolized rodent excretions), direct contact with infected fluids

virulence: disruption of clotting factors

culture: ELISA

prevention: avoiding rats, safe food storage

treatment: Ribavirin

• chest pain, deafness as long term sequelae

Anaplasmosis (upper midwest/northeastern US)

• transmission: tick borne intracellular bacteria

• fever, headache, muscle pain

• agent: Anaplasma species

culture: PCR, indirect antibody test

prevention: avoid ticks

treatment: doxycycline

Acute endocarditis

causative agent: staphlococcus aureus, streptococcus pyogenes, S. pneumoniae, Enterococcus, Pseudomonas aeruginosa,

transmission: parenteral

culture/diagnosis: blood culture

prevention: aseptic surgery, injections

treatment: Vancomycin; surgery

distinctive features: acute onset, high fatality rate

greatly increased incidence due to heroin epidemic

Subacute endocarditis

causative agent: Alpha-hemolytic streptococci, others

transmission: endogenous transfer of normal biota to bloodstream

culture/diagnosis: blood culture

prevention: prophylactic antibiotics before invasive procedures

treatment: broad spectrum antibiotics; surgery may be necessary

slower onset