Zoonoses Flashcards
Define zoonoses
Diseases that pass between living animals and humans (where animals are the source of the disease)
What are anthroponoses?
Diseases spread from humans to animals
Give examples of anthroponoses
Influenza (virus infecting pigs, birds), strep throat (bacteria infecting dogs), leishmaniasis (parasite infecting dogs), chytridiomycosis (fungus affecting amphibians)
Toxoplasmosis only tends to infect humans when they are what?
Immunosupressed
What are the common zoonoses in the UK?
Salmonella Campylobacter Toxoplasmosis Psittacosis Q-fever Ringworm
What causes psittacosis?
Chlamydophilia psittaci
What causes Q-fever?
Coxiella burnetti
What causes ring worm?
Dermatophytes
What zoonoses are rarely seen in the UK now?
Anthrax
Rabies
Bubonic plague
What is anthrax?
Bacteria spread by contact with bacterial spores (often in infected animal products)
Can lead to skin/lung/GI disease
What is bubonic plague spread by?
Insects & small animals
What is tularaemia?
Bacterial infection transmitted by ticks, deer flies, infection animals
Presents with fever, skin ulcer, tenderness, regional lymphadenopathy
Define emerging zoonoses
Zoonosis that is newly recognised/evolved/that previously occurred but now shows an increase in incidence/expansion in geographical/host/vector range
Give examples of emerging zoonoses
Avian influenza Nipah virus (SE Asia --> severe encephalitis) Rabies Brucellosis Moneypox
What is monkey pox?
Similar to small pox
Flu like stage –> eruption of maculopapules which develop into vesicles –> pustules & crusts
What is rabies infection with?
Lyssavirus
How is rabies spread?
Transmission via saliva from bite by infected animal
What animals tend to be carriers for rabies?
Mostly dogs and bats
Also monkeys, foxes, racoons, skunks, wolves, cats
What is the incubation period for rabies?
2wks-several months
How does rabies virus spread in the body?
Travels to brain via peripheral nerves
Further the bite is away from brain, the longer it will take to travel
Once rabies reaches the CNS what is the prognosis?
100% fatal
What is the clinical presentation of rabies?
Acute encephalitis:
Malaise, headache, fever, mania, lethargy, coma
Unable to swallow
Hydrophobia (involuntary pharyngeal muscle contraction when try to drink - pathognomic)
How do most people die of rabies?
Respiratory failure
How do you diagnose rabies?
PCR of saliva/CSF
Mostly confirmed on post-mortem brain biopsy
How do you Rx rabies?
Immediately after bite give PEP:
Cleaning & debridement
Human rabies Ig (esp around wound if poss.)
4 doses of rabies vaccine over 14 days
Who did brucellosis used to affect?
Farmers, vets, slaughterhouse workers
Where are the brucellosis organisms excreted?
Milk, placenta, aborted foetus
When are humans at risk of being infected with brucellosis?
Milking/birthing infected animals
Handling carcasses of infected animals
Drinking unpasteurized diary products
When sending a suspected brucellosis sample to the lab what must you do?
Warn them as it may spread in lab
How do you diagnose brucellosis?
Culture with prolonged intubation time & serology
What kind of microorganism is brucellosis?
Small, gram -ve coccobacilli
What are the three species of Brucella and where do they mostly come from?
Melitensis - goat, sheep, camel
Suis - pig
Abortus - buffalo, cattle
What is the incubation period for Brucella?
5-30d
What are the symptoms of brucellosis?
Acute (1-3wk): high, undulant fever, weakness, headaches, drenching night sweats, splenomegaly
Subacute (>1m): fever & joint paints (knee, hip, SI joints)
Chronic (m-yrs): flu like symptoms, malaise, depression, chronic arthritis, endocarditis, epididymo-orchitis, rarely meningism, splenomegaly
Subclinical
(most common)
What should make you think brucellosis?
Unspecific acute presentation, sweating, travel Hx, nonresponsive to antibx
How do you Rx brucellosis?
Long acting doxycycline for 2-3m & rifampicin/IM gentamycin for first weeks
Add cotrimoxazole for 2 weeks if CNS dx
What causes leptospirosis?
Spirochaete Leptospira interrogans
Mostly L. hardio from cattle
What symptoms does L. hardio leptospirosis lead to?
Fever, meningism
What are the life cycle of leptospira like?
Survive in environment for weeks/months
Direct transmission to humans via broken skin/mucous membrane & contact with infected animal urine
Why is the incidence of leptospirosis increasing?
Recreational, e.g. increased white water rafting etc.
Unexplained emergence in Thailand
Climate change/disaster assoc, e.g. floods
What is the incubation period of leptospirosis?
2-10d
What are the symptoms of leptospirosis?
Undifferentiated fever, myalgia, headaches, abdominal pain
How do you manage leptospirosis?
85% get better & don’t need Rx
10-15% get severe dx:
Weil’s disease/pulmonary haemorrhage
What triad do you get in Weil’s disease?
Jaundice, AKI, bleeding
When should you think about leptospirosis?
Fever in cattle farmer
Exposure to rats/water
Someone who works in an abattoir
Vets/sewage workers
What tests should you do for leptospirosis?
Culture (blood/CSF), serology & PCR
How do you Rx leptospirosis?
Doxycycline for mild dx
IV penicillin for severe
Haemodialysis
Mechanical ventilation
What causes lyme disease?
Borrelia burgdirferi (spirochaete) found in wild deer
What transmits lyme disease?
Tick (lxodes Ricinus) which active above 4C
Usually nymph that carries it
What are the stages of lyme disease?
Early, localised (3-30d): target board erythema migrans Early disseminated (wks-months): borrelial lymphocytoma (bluish/red plaque/nodule - check earlobes, nipples, genitalia), may also get neuroborreliosis or cardiac disorders (peri-myocarditis/heart block) & arthritis (more in USA) Late disseminated (months-yrs): acrodermatitis chronica atroficans, lyme arthriris, peripheral neuropathy
What is ACA?
Focal inflammation then atrophic skin
Caused by infection with B. afzelii
What is lyme arthritis?
Bluish-red discolouration of extensor surfaces of extremities most commonly
How do you diagnose lyme disease?
EM can be diagnosed clinically
ELISA - if +ve/equivocal –> immunoblot test to confirm
ELISA -ve - repeat in 4-6 weeks if still suspected
ACA/lymphocytoma - clinical and high serology titres
Arthritis - serology titres from synovial fluid/PCR
How do you Rx lyme disease?
Oral doxycycline/amoxicillin
IV ceftriaxone if disseminated
Treat 21 days (28 for arthritis/ACA)
How is leptospirosis ‘classically’ spread?
Infected rats urine
What is leptospirosis aka?
Weil’s disease (although this term is sometimes reserved for the most severe cases associated with jaundice)
What reaction is sometimes seen after initiating antibiotics to treat Lyme disease?
Jarisch-Herxheimer reaction
