Zoonosis and Emerging Infectious Disease Flashcards
EID
emerging infectious disease
what are the 3 major groups of EIDs?
- EIDs associated with spill-over from domestic animals to wildlife populations
- EIDs related directly to human manipulation such as host or parasite translocations
- wildlife spill-over to humans/domestic animals EIDs with no overt human or domestic animal involvement
which are the most widespread bacterial zoonotic infections?
salmonellosis (Salmonella) as well as campylobacteriosis (Campylobacter)
Methicillin-resistant Staphylococcus aureus (MRSA)
newly emerging strain of a common microscopic germ that lives on the skin and nasal passages of humans/animals
Lymphocytic Choriomeningitis Virus (LCM)
host: house mouse (mus musculus)
hamsters and guinea pigs are not natural host but can transmit
transmission: urine/feces contact, bites, inhalation of urine/feces particles, ingestion of contaminated food
what needs to happen when LCMV is diagnosed in a research lab?
all animals exposed need to be tested and positive animals need to be euthanized
LCM human CS
flu-like symptoms
usually resolved but can develop meningitis
meningitis symptoms
stiff neck, fever, headache, malaise, muscular pain
LCM transmission in humans
pregnant women may transmit the virus to the fetus resulting in fetal death or severe abnormalities
ORF
contagious ecthyma or “sore mouth”
poxvirus
host: sheep, goats
transmission: contact with lesions
ORF CS
animals: lesions that can last up to 6 weeks
humans: long lasting sore, not fatal
how is ORF controlled?
vaccinate, wear gloves around sheep
ORF treatment
treat secondary infections
rabies and opossums
opossums have a low body temperature that makes the virus unable to survive
rabies animal CS
behavior changes, paralysis, death
rabies human CS
dysphagia, paralysis, death nearly 100% within 2-10 days
rabies infection stages
- prodrome: headache, nausea, vomiting, agitation, anxiety
- acute neurologic phase: encephalitis or paralysis
- coma/death
rabies treatment
none after symptom onset
when there is a possibility of rabies infection postexposure prophylaxis (PEP) is administered
what does PEP consist of?
wound care, rabies immunoglobulin, 4 doses of vaccine (on day of exposure, day 3, day 7, and day 14)
rabies vaccine and immunoglobulin should not be administered at same site or with same syringe
Milwaukee rabies protocol
induction of coma, ketamine and antivirals given
not given vaccine or immunoglobulin, just trying to suppress brain activity while the body fights the virus
has a low success rate, high cost, and ethical debates
Hantavirus
HPS (Hantavirus Pulmonary Syndrome) in US
host: rodent (deer mouse in Midwest, cotton rat in Southeast)
transmission: aerosol of dried feces/urine/saliva
HPS
flu-like symptoms with rapid progression into respiratory failure
HFRS
hemorrhagic fever with renal syndrome in Asia
monkeypox
same genus as smallpox and cowpox: orthropox virus
natural host unknown but African rodent spp. suspected to play a role in transmission
cause of outbreak traced to Gambien pouched rats imported into US
arboviral zoonosis
transmitted through arthropods: mosquitos most common but ticks can too
most were originally found in tropical regions but due to global warming, increased urbanization and population size, faster transportation, and rapid arthropod vector spread arboviruses are continuing to spread into new areas
EEE, WEE, and WNV
normally a cycle between birds and mosquitos with humans and horses as dead end hosts
EEE virus: only a few cases in US but can be fatal or cause ongoing neurologic problems in survivors
West Nile Virus (WNV)
most animals are subclinical carriers: horses show the most signs which include neurological signs like ataxia and paralysis
humans and horses are dead end hosts; chickens are sentinels; birds are amplification hosts
West Nile Fever
most common form of WNV
flu-like symptoms which resolve but persistent fatigue
neuroinvasive form of WNV
immunocompromised humans are more susceptible
encephalitis, meningitis, paralysis, death
survivors may have permanent neurologic signs
Chikungunya, Dengue, and Zika virus vector
aedes aegypti
chikungunya
most feel better within a week but joint pain can persist for months
dengue
acute or severe forms
severe form CS: fever, nausea/vomiting, joint pain, rash, headache; can cause a life threatening hemorrhagic fever within hours
zika virus CS
fever, rash, joint pain, headache, red eyes
zika virus
linked to microcephal: the severe brain damage affects all aspects of a child’s development both physical and mental
Gillain-Barre syndrome (GBS)
caused by zika virus
uncommon sickness of the nervous system where a person’s own immune system damages nerve cells causing muscle weakness and paralysis
avian flu: HPAI/LPAI
closely related to influenza virus A of humans, pigs, horses, and dogs
antigentic drift: point mutations
antigentic shift: genetic reassortment
pigs are receptors for swine flu, avian flu, and human flu
bird flu outbreaks: H5N1
wild birds are subclinical carriers
HPAI viruses have been eliminated from domesticated poultry in US and Canada but viruses can be reintroduced from imported poultry, wild birds, or pet birds
swine flu
H1N1
Lassa virus
hemorrhagic virus
reservoir host: rodents
transmission: contact with food/household items contaminated with rodent urine/feces or aerosolization
BTT: aerosol
Marburg
reservoir: Egyptian fruit bat
transmission: direct contact, insects
acute CS: flu-like leading to hemorrhagic fever (vomiting/diarrhea leading to DIC, thrombocytopenia, and hemorrhage)
ebola
BTT: aerosol
continues to resurface but exact sources are unknown
transmission: intimate person-to-person contact
CS: initial cold-like symptoms that rapidly progress causing massive internal and external bleeding with accompanying dehydration
Hendra
paramyxovirus
novel virus related to canine distemper
reservoir host: flying fox
amplification host: horse (acquire from bats roosting above water troughs)
case fatality rate: 40-75%
Nipah virus infection in humans
caused by Hendra paramyxovirus
can be subclinical to acute respiratory infection and fatal encephalitis
severe acute respiratory syndrome (SARS)
coronavirus
person-to-person contact through respiratory droplets, indirectly through fomites
epidemic/pandemic requirements
- new disease must emerge in a species with little to no immunity
- virus must produce disease in that species
- sustainable transmission must occur in new species
epidemic or enzootic
outbreak of disease in a contained area
pandemic
disease spread
MERS-COV
suspected amplification host: dromedary camels
suspected reservoir host: bats
Middle East respiratory syndrome (MERS): viral respiratory disease caused by Middle East respiratory syndrome coronavirus
SARS-COV-2
COVID-19
possibly originated in bats
“wild flavor”
new trend of eating wild animals is causing virus jumping
wet markets encourage this by consisting of different meats in a big pile touching each other
prevention of zoonotic disease
good hygiene, good animal husbandry, vector protection, respect for wildlife
zooprophylaxis
dilution effect theory
increasing biodiversity dilutes disease transmission by diverting infection away from the reservoir host
