VPH- Final 1

untimely's version from 2015-04-27 01:34

Lyme and Ehrlichia

Question Answer
how do most dogs with lyme present?90% of dogs exposed do not show clinical signs (disease). There can be Acute onset polyarthropathy and accompanying pyrexia, though. MOST SERIOUS LONG-term DISEASES FROM LYME IS... Glomerular disease due to Ag/Ab complexes, and Cardiac & neurologic disease (rare)
are there vx for lyme for dogs?YES
is lyme dz re-portable? notifiable? in animals or people?REPORTABLE IN PEOPLE.
what is the MAINTENANCE HOST for Lyme? VECTOR?(NOTE: more detailed later about geographic location, but in general) HOST: infected wild animal spp. VECTOR: Density of Ixodidae ticks [hard ticks] (Little transovarian transmission occurs in ticks, although there is transtadial)
how do humans relate to the maintenance cycle of lyme?humans are an accidental host but NOT a dead end host!
describe how the vector for lyme can vary based on geographic location?(1) EAST COAST: Ixodes scapularis (the deer tick)- 25-50% of ticks infected. (2) WEST COAST: I. pacificus (the Western black-legged tick)- 1-5% of ticks infected
on the EAST COAST what are the main maintenance hosts?White-footed deer mice(principal reservoirs host) and deer
how do white-footed deer mice contribute to the maintenance cycle of lyme in the east?****CRUCIAL TO MAINTENANCE! because they remain spirochetemic but tolerant to infection. (can pass to uninfected ticks)
explain if/how/whats going on with ticks and how they can maintain lyme?NOT transovarian, but CAN have Transtadial transmission from larvae to nymph. So, Uninfected larval ticks feed on deermice--> become infected nymphal ticks--> Nymph infect other deermice and dogs/humans--> Infected mice source of infection > naïve larval ticks
how do white-tailed DEER play a role in the maintenance cycle of lyme?NOT INVOLVED IN LIFE CYCLE!! don't become spirochetemic enough to infect adult ticks. However, they are food to sustain the tick population, so that's something
explain the cycle for the WEST coat with lyme dz, and how it compares to the east coast cycleBOTH SPECIES OF TICKS are required for infection of humans. this is because the WOOD RAT and I. neotomae ticks maintain the dz in the area, but this tick RARELY Bites humans or dogs. Which means Uninfected, I. pacificus ticks, occasionally bite an infected woodrat and the tick then bites horses, dogs, humans (this is why there is Much lower infection rate in West Coast ticks)
How do humans get lyme dz?THEY GET BIT BY A TICK!!!! (east coast, Ixodes scapularis (the deer tick) and west coast, I. pacificus). USUALLY the bite is from a nymph. which must remain attached for 24 hrs or more to transmit the spirochete
**what is crucial for the transmission of the lyme spirochete from the tick bite?takes 24 hours to transmit!!! so IMPORTANT TO REMOVE TICK EARLY ON
is it possible for lyme to be transferred human to human?yes, rare, but transplacental and sexually transmitted possible
how does lyme dz usually present in humans?Presentation highly variable. Usually flu-like disease-- usually THREE BODY SYSTEMS AFFECTED: Cutaneous (erythema migrans), Neurological, Musculoskeletal (dz usually progresses in stages)
how can you dx dogs with lyme?DIFFICULT! hx of tick exposure helps, along with Clin signs of SHIFTING LAMENESS, pyrexia,swollen joints. If tx, there will be RAPID RESPONSE to antimicrobial therapy. Upon serology, a "significant" positive titer as evidence of exposure. Paired titres important for current infection. High antibody titers do occur in asymptomatic dogs!!!!! important to know infected animal may initially test seronegative.
how do you know if a dog was exposed to lyme? infected?exposure= elevated Ab titer. infected=PAIRED titers
what are some Common Currently used Diagnostic tests in dogs?PCR detection (not widely avail), SNAP tests, C6 Antibody Testing:Currently 2 commercially available tests for canine antibodies against the Lyme C6 peptide. NOTE: No blood test can confirm Lyme Disease in dogs!!!
what is meant by a C6 titer?C6 is a peptide on the lyme organism which you can form an Ab against. Can test for this Ab, look at a titer for it and can tell infection based on pre and post treatment measurements of it. (Quantitative C6 titer drops with a/biotic therapy).
how do we try to prevent confusion between Abs from vx and Abs from exposure?Traditional ELISA for antibody cannot distinguish:vaccine - induced antibodies from antibodies due to natural exposure. B.burgdorferi expresses several [OspA –C] Proteins but only when in the tick gut. These proteins used as vaccine antigens. However, Another outer membrane protein, C6 is only expressed by living B.burgdorferi+ is not used as a vaccine antigen. So use C6 as a way to tell if the dog was exposed/infected instead of just vx
if you test positive for C6 Abs, what does this mean?dog was EXPOSED/ infected, NOT FROM VX
how are dogs treated for Lyme?Dogs with acute Lyme arthritis respond rapidly to amoxicillin or tetracyclines (doxycycline)-(within 36hrs). Acute cases tx for 2 wks, chronic for 4wk. (Optimum period/dose not established by clinical trials)
what are you thinking if dogs with chronic arthritis doesnt respond to abx tx?may have immune-mediated polyarthropathy, & req. steroids
why is the lyme vx controversial?most dogs dont get dz and some questioning abotu effectiveness of dz.
what is the rare but most serious canine presentation of lyme?Screen for proteinuria, bc Lyme nephritis is severe
if you dx lyme, what else must you consider?coinfections, because of being tick bourne and they carry a lot of different dz agents
what is super important to stress to owners about lyme dz?Even in vaccinated dogs TICK CONTROL must be stressed to the owners since a very heavy B. burgdorferi burden may override vaccinal protection.
is there a vx for people against lyme? what should you know?not in development, but there are problems: poor demand, costly, Req. series of 3 vaccines/boosters to maintain titers, AND RISK OF AUTOIMMUNE ARTHRITIS
Prevention and control: Your role on educating clients on what for lyme? the importance of approved tick control [acaricides that kill ticks] in the environment, and tick repellents and EPA approved acaricides for pets. Vaccination alone or treatment alone is insufficient unless combined with vector control measures and advising owners on preventing tick exposure to them and their animals. Ticks carried by dogs [not dogs themselves], are the source and reservoir of infection to humans and it is important that owners are aware of the risks to human health posed by ticks that may carry multiple zoonotic agents.
what are the 4 species of zoonotic ehrlichia?Ehrlichia chaffeensis, Ehrlichia ewingii, Anaplasma phagocytophilum (formerly Ehrlichia phagocytophila), E. canis(<--not really)
what are the 4 main tick born diseases in cats?Anaplasma phagocytophilum, Cytauxzoon felis, F. tularensis-zoonotic, Ehrlichia spp-little known (Bartonella spp.Ticks are also a possible vector)
what is the ehrlichia agent maintenance cycle like?Agents maintained within a tick – wild animal cycle
what are the biological vectors of ehrlichia/anaplasma sp? (3)Hard ticks (family Ixodidae) of Genera--> 3 sp: (1) Amblyomma spp (2) Dermacentor spp (3) Ixodes spp.**human diseases in the United States
E. chaffeensis-- main host?White-tailed deer (deer chaffed me last night)
E. ewingii-- main host?Deer mainly but Dogs? reservoir host in areas
A. phagocytophilum-- main host?Cervids & rodents reservoir hosts
what are the Accidental, dead-end Hosts for ehrlichia/anaplasma species, and how do they get infected?humans, dogs. Via tick bite.
what causes human monocytic ehrlichiosis?E chaffeensis (my deer one chaffed me)
what causes human ehrlichiosis?E. ewingii (dog one)
what causes human granulocytic ehrlichiosis?anaplasma phogocytophylum (horse one) (GA!!!)
how do you tx ehrlichia/anaplasma sp?The drug of choice for all forms of ehrlichiosis is doxycycline or other tetracyclines
is there dog-to human xmission of ehrlichia?While there are no reports of direct dog-to-human transmission of either E. ewingii or E.chaffeensis, identification of an infected pet would suggest the pet’s owner is at risk of exposure to infected ticks

Bats and Zoonoses (focus on henipaviruses)

Question Answer
Henipaviruses encompass what two viruses? what kinda viruses are they?Hendra and Nipah viruses. zoonotic paramyxoviruses (henipavirs and "O" in henipa so no orthmyxo!!)
Hendra and Nipah viruses are harbored by what kinda bats?fruit bats
intermediate host for Hendra?horses (hendra horses)
intermediate host for nipah?pigs (nipa, pigs)
how do humans get infected with hendra/nipah?contact with INTERMEDIATE host (horse/pig)
3 recently discovered zoonotic viruses carried by bats in australiaHendra virus, Australian bat lyssavirus, Menangle (another paramyxo)
is there a vx for hendra?yes, for horses! (Vaccine consists of Hendra virus surface protein, G, known target for triggering host immune response.)
how does a human play into the role of the lifecycle of hendra?accidental dead end hosts
how is hendra NOT transmitted?No evidence bat-human; human-human; human-horse
how does a person get infected with hendravirus?contact with infected HORSE! horses serve as amplifiers to infect humans (no contact with bats will lead to infxn in humans)
what is the reservoir hose in hendra virus, and how is the virus shed?Pteropid (FRUIT BAT) res. host--> shed virus in saliva, urine, semen, feces (specifically: Little red flying-fox, black flying-fox, grey-headed flying-fox, spectacled flying-fox)
do fruit bats show signs of hendra virus?no.
who can bats spread hendra virus to?HORSES, and other bats (stress factors)
who can horses spread hendra to?HUMANS (amplifier host), and also other horses(but this is limited)
how can horses be infected with hendra from bats?could be from ingesting food/water/pasture tainted with bat feces//urine/salive/birthing fluids/ other bodily fluids
how does hendra usually spread from bat to bat?Virus shed in bat feces, urine, saliva --> spread easily within a bat colony. More likely to be spread during repro/nutritional stress
how does a horse transmit hendra to a horse?RARE, but can happen..close contact, virus shed in oral secretions and urine, and can be Aerosol transmission in a contaminated environment
how can a horse infect a human with hendra?Cutaneous from infected horse saliva to human, Aerosol at necropsy (usually need close contact, transmission to humans is not very efficient) (result of direct exposure to infected or dead horses.)
how does hendra present in a horse?Fever, tachycardia..deteriorate quickly ~75% die. Respiratory +/- CNS signs
can a horse have a carrier state of hendra?no
what is hendra dz like in humans?Self-limiting flu-like + severe pneumonia /death. Aseptic meningitis with recovery, then death from encephalitis 13 months later
HeV (hendravirus) control in flying fox populations unfeasible due to...Size of their populations, Geographical range, Migratory activity, which is beyond Australian borders
what are some ways to prevent horse-to-human transmission of hendra?Isolation of ill horses, Quarantine horses exposed to horses testing + for HeV, Australian government determines fate! Euthanase?, VX HORSES!
what's the mortality rate of hendra in humans?50% human mortality rate but disease rare
The natural host for Hendra virus is the...flying fox
which henipavirus has a CDC category for bioterrorism, and what is it?Nipah, category C
what BSL (biosaftey level) are hendra and nipah?level 4 (highest category, super dangerous)
****which henipavirus has human-human spread?nipah!
**which henipavirus has a vx?HENDRA-- NO VX FOR NIPAH
does nipah affect the pigs?YES bad for them too
do bats show signs of nipah virus?NO, they are natural hosts and symptomatic
hosts of nipah virus?bats (the Island flying-fox, Malayan flying fox)
how do bats shed nipah virus?Virus found in urine, saliva, uterine fluids of bats
how do pigs shed nipah virus?Pigs shed virus in respiratory secretions, saliva, urine.
how do humans realate to the life cycle of nipah virus?they are accidental hosts-- NOT dead end hosts, as some human-human in Bangladesh
who can Pigs spread nipah virus to?other pigs, and humans!!
who can bats spread nipah virus to?to PIGS, and in Bangladesh and India, also to humans (drinking date palm juice tainted with bat saliva/feces)
can humans spread nipah virus?limited evidence of human-human-- huge pandemic implications
how do pigs usually spread nipah to other pigs?aerosol (coughing) due to virus being shed in secretions
how do bats transmit nipah to pigs?Increasing overlap between bat habitats and piggeries>Pigs eat fruit from trees near piggeries. Fruit may be contaminated with bat saliva+urine.
how do pigs spread nipah to humans?DIRECT CONTACT WITH PIGS. Aerosolisation or direct contact with respiratory secretions, urine or saliva from infected pigs
which virus is spread human-human, and how?NIPAH, Aerosol, Between friends/family members who cared for cases, Ingestion via saliva? Care providers shared eating utensils/leftover food and shared beds with patients
how do humans present when infected with nipah?Fever, vomiting, myalgia, encephalitis (may relapse after recovery), meningitis, Neurologic deficits, Coma, death (some will have seizures and become comatose)
how do pigs present when infected with nipah virus?Porcine respiratory and neurologic syndrome also known as BARKING PIG SYNDROME! also CNS, twitching/trembling, …hind limb paresis, death after onset of respiratory distress, ..Some affected pigs may be asymptomatic.
how do bats present when infected with nipah virus?NO CLINICAL SIGNS

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