Lab Presentations

lassa fever virus

• acute hemorrhagic illness endemic to West Africa

• transmition: via contact w/ infected rats

  • contaminated food (rat feces), direct contact, inhalation of infected particles

• 80% asymptomatic but severe cases cause multi-organ failure w/ 20% mortality

• chronic cases lead to hearing loss and viral persistance

• treatments:

  • no current vaccine

  • ribavirin w/ varied success rates

  • hard to diagnose due to infection being asymptomatic

taenia saginata

• beef tapeworm from undercooked meat

• intestinal parasite that infects cattle and forms cysts → then infects humans

• worm can grow 10-25m long

• proglottids = segments w/ eggs

• worm absorbs nutrients through body structure and lives in SI

• transmission: fecal-oral

• pt is usually asymptomatic or weight loss/nausea/mild stomach pain

• treatment:

  • praziquantel

  • eating fully cooked beef

hepatitis B

• virus w/ surface antigens

• can survive up to 72 hours outside of the body through bodily fluids (dry blood, etc)

• hosts are humans only, w/ target cells being hepatocytes

  • leads to liver inflammation, hepatocyte damage, cancer

• sources: blood, sexual contact, perinatal, needle sharing

• transmission:

  • entry: broken skin, mucous membranes, bloodstream

  • exit: blood, semen, vaginal fluids

• during acute infection, symptoms may/may not appear for first 6 mo

• during chronic infection, infection lasts more than 6 mo

  • more lethal in children, adult immune system can clear infection 90%

  • healthcare workers, IV drug users

• pts experience fatigue, jaundice, dark urine, etc

• high risk areas are sub-saharan africa + east asia

• treatments:

  • no cure for chronic HBV

  • antiviral meds

  • highly effective recombinant HBV vaccine

  • screening of blood + safe needle practices

helicobacter pylori

• spiral shaped, motile, gram- bacterium

• lives in mucosal lining of stomach

• microaerophilic

• makes urease → neutralizes stomach acid to grow in intestines

• transmission: fecal-oral or saliva

• chronic infection, initially asymptomatic but leads to gastritis or cancer

• causes abdominal pain, nausea, loss of appetite

• treatment:

  • PPI, antibiotics

cryptococcus neoformans

• encapsulated, non-motile yeast fungus living in soil + pigeon droppings

• capsule is virulence factor, makes urease

  • prevent killing + immune recognition

  • survives macrophage

• transmission: inhalation of desiccated yeast cells or basidiospore

• primary infection in lungs (alveoli), spreads to bloodstream and infects BBB + meninges

• birds are carriers (not infected)

• exits when humans are dead

  • most common in immunocompromised people, HIV/AIDS pts, transplant recipients

• causes cryptococcosis, pulmonary infection, fungal meningitis

• pts experience cough, shortness of breath, fever, confusion/changes in behavior, vomiting, sensitivity to light, atypical pneumonia

• treatments:

  • Amphotericin B and flucytosine (short term)

  • Fluconazole (long term)

  • May require lifelong therapy, no vaccine available

rabies virus

• bullet-shaped, enveloped, negative sense ssRNA virus

• attacks nerves and brain

• reservoir → dogs, bats, raccoons, cats, etc

• mostly in Asia and Africa

• transmission: saliva into broken skin, animal bite

  • headache, fever, fatigue, hydrophobia, paralysis, aggression

• acute infection that replicates in muscle and travels to brain

  • causes encephalitis

• treatment:

  • vaccine, PEP, clean wound immediately

toxoplasma gondii

• obligate intracellular protozoan parasite

• acute infection causes flu-like symptoms, latent infection lives in muscle/brain

  • symptoms include ocular toxoplasmosis, blurred vision, floaters

• definitive hosts are cats, humans are accidental hosts

• transmission: humans are infected from food, environment, cat feces, contaminated water

  • enters via congenital transmission ingestion of undercooked meat

• chronic infection in immunocompromised, pregnant women are also susceptible

• treatment:

  • Pyrimethamine + sulfadiazine + folinic acid

  • avoid cat litter during pregnancy, eat cooked meat

corynebacterium diphtheriae

• part of DTaP vaccine

• non-motile, aerobic, G+ bacillus

• in nasopharynx and inhibits cell protein synthesis but may involve any mucous membrane

• controlled infections via vaccinations, most cases are nontoxigenic

• A-B toxin causes tissue death and lesion formation, lesions last 2-6 weeks w/o treatment

• transmission: excreted through respiratory secretions/skin discharge

• pts experience pseudomembrane in nose/throat, fever, sore throat, open sore/ulcer, pain, rash, swelling, redness

adenovirus

• causes respiratory illness/symptoms, pneumonia, conjunctivitis

• dsDNA virus, non-enveloped

  • non-enveloped nature makes it resistant to drying + disinfectants

• transmission: respiratory droplets, fecal-oral secretions in humans, contaminated objects

• also enters mammals, birds, reptiles, fish

• 100 human serotypes, remains on contaminated surfaces/objects/water for long periods

• virus binds to cell receptors → enters via endocytosis

• lytic replication in epithelial cells leads to rapid onset of symptoms

  • respiratory, GI, ocular, urinary tracts

• treatments:

  • no approved antiviral meds

  • common OTC meds

  • vaccine for military only