Environmental Zoonotic Diseases Flashcards
What factors affect the following pathogens to survive in the environement?
- viruses
- bacteria
- protozoan parasites
- helminths
- prions
- Viruses: humidity, temperature, light, matrix – general rule: soft surfaces kill viruses more quicly as does low himidity and exposure to sunlight
- bactera: matrix, persistence within feces or animal tissues, spore-formation
- protozoans: matrix, persistence within feces or animal tissues, ability to encyst
- helminths: ability of eggs to survive harsh conditions
- prions: transmission via consumption of tissues, exposure to bodily fluids (pretty hardy)
What makes anthrax persistent in the environment?
exists as an endospore
Describe the transmission cycle of anthrax
infected animal –> biting fly –> bites human (cutaneous)
ingestion of contaminated meat
animal decomposition –> anthrax spores in environment –> inhalation or gets into an open wound in humans
Describe the anatomy of an athrax spore and the function of each structure
- core (Cr): houses chromosomes + SARPs –> protection against UV and heat
- cortex (Cx): layer of PG –> keeps spore dry
- coat (Ct): multilayered protein shell –> prvents entry of toxins and attack by other microbes
- interspace (IS)
- exosporium (Exo): interacts with the environment
What are the three forms of anthrax disease in domestic animals?
- apoplectic
- acute and subacute
- chronic
What happens to anthrax is dead animals and in oozing blood?
- dead animal: readily destroyed by anaerobic bacteria
- blood: develops into spores
What are the 3 forms of athrax disease in humans? Describe the tranmittence of each
- pulmonary – inhaling spores
- gastrointestinal – ingestion of spores
- cutaneous – contact with infected caracasses, contaminated wool, hides, etc
In anthrax pulmonary disease, how does the bacteria gain access to the pulmonary draning lymph nodes and thus go systemic?
- trojan horse model: hitches a ride in lung phagocytes to PLNs where it escapes
- jailbreak model: breaches the epithelial/endothelilar barrier –> enters PLN
What are the two plasmids in athrax? what do they encode for?
- PX01: encodes edema factor, lethal factor and protective Ag
- PX02: encodes antiphagocytic capsule
Describe the effects of the following antrax virulence factors:
- poly D glutamic acid capsule
- edema factor
- lethal factor
- capsule: inhibits phagocytosis, linear polymer that is weakly antigenic
- edema factor: inactivates neutrophils via adenyl cyclase which cleaves ATP –> cAMP and floods cells with cAMP to disrupt signaling pathways
- lethal factor: targets endotherial cells –> vasuclar leakage –> low blood volume –> septic shock; proteases that cleaves MAPK kinases –> disrupts signaling pathways
What does anthrax’s protective Ag do?
creates a pore that facillitates entry of EF and LF into cells
How can anthrax be diagnosed?
- microscopic examination of blood smears
- PCR amplification of EF or LF
- inoculation of lab animals
What are the treatments for anthrax?
early antibiotic treatment
what do old world vs new world hantavirsuses cause?
old world –> HFRS
new world –> HPS
Why is there seasonality with HFRS?
- harvesting of wheat in summer
- harvesting rice in late fall
fields with rodent excreta –> harvesting kicks up a lot of dust
