Zoonoses Flashcards
Zoonoses
Infections that can pass between living animals and humans
Who is the source of infection in zoonoses?
animal
Who definition of zoonoses
Infections that are naturally transmitted between vertebrae animals and humans
Is malria a zoonosis? why?
no
depend on the human host for part of their life cycle
Describe anthroponosis and examples
reverse zoonoses when humans infect animals
influenza and strep throat
4 causative pathogens of zoonoses
bacteria, virus, fungi and parasites
2 strategies pathogens develop to ensure their survival/propagation
cause chronic infection to survive
non-human reservoir eg monkey
List some common zoonoses in the UK
campylobacter toxoplasma salmonella Q fever ringworm psittacosis
Define emerging zoonosis
A zoonosis that is newly recognised or evolved that has occurred previously but shows an increase in incidence or expansion of host, vector or geographical area
Name some emerging zoonoses
monkey pox
avian influenza
rabies
brucellosis
Causative organism of rabies and describe it briefly
lyssavirus - viral infection
transmitted from bite of infected animal and mainly is dogs and bats
Incubation period of rabies and how does it travel to the brain?
2 weeks to several months
peripheral nerves
Acute encephalitis features of rabies
malaise, headache and fever mania, lethargy, coma overproduction of saliva and tears unable to swallow and hydrophobia death by resp failure
Diagnosis of rabies
difficult
PCR of saliva or CSF
often by most mortem or brain biopsy
Is rabies always fatal if untreated?
yes
Explain the post exposure prophylaxis procedure after a bute
human rabies immunoglobulin - HRIG
infiltrated around the bite if possible
+ 4 doses of rabies vaccine over 14 days
How is brucellosis passed on?
organisms excreted in milk, placenta and aborted foetus
4 ways humans can be infected with brucellosis
during birth
consume infected unpasteurised products
milking infected animals
handling carcasses of infected animals
Why must you warn the lab in brucellosis?
risk of spread
Describe the brucella bacteria
small, gram negative, coccobacilli
Incubation period of brucellosis
5-30 days but can be up to 6 months
Treatment of brucellosis
long acting doxycycline for 2-3 months and rifampicin or Im gentamicin for the 1st week
add cotrimoxazole for 2 weeks in CNS disease
Acute presentation of brucellosis
fever, headache, sweats and splenomegaly
Subacute presentation of brucellosis
fever and joint pains - knee, hip, back (SI)
Chronic presentation of brucellosis
flu like chronic arthritis and endocarditis
subclinical presentation of brucellosis
50% exposed have positive serology
Who was leptospirosis common in?
NE Scotland fish workers and miners - rat bites and urine
Causative organism of leptospirosis
L. icterohaemorrhagica and L.hardjo
Symptoms of leptospirosis
flu-like then jaundice and renal failure
How does leptospirosis get into the human?
penetrate abraded skin or mucous membranes
Why is leptospirosis one of the most widespread zoonoses?
survive in environment for weeks to months
Explain the changing epidemiology of zoonoses
traditionally an occupational disease
no seen in Thailand and climate change/disasters
Severe leptospirosis can lead to…
weil’s disease
pulmonary haemorrhage
death
weil’s disease
traid of jaundice, AKI and bleeding
Diagnosing leptospirosis
think of it - fever in cattle farmer or those in contact with water and rats
microscopic agglutination test - paired sera
ELISA serology, PCR, culture?
Treatment of leptospirosis
doxycycline - mild
iv penicillin - severe
prompt dialysis and mechanical ventilation
How is lymes disease transmitted and the name of this
tick
ixodes ricinus
What time of year is lyme most common? Why?
summer - ticks like humidity and active >4 degrees
Erythema migrans
80-90% cases and is a clinical diagnosis with multiple or single lesions
ACA (lyme)
elderly, European, extensor surfaces of distal extremities
bluish red discolouration and peripheral neuropathy
Lymphocytoma
bluish solitary painless nodule on earlobe or aerola
children
Neuroborreliosis triad
facial palsy
radicular pain
lymphocytic meningitis
USA lyme differences
cardiac disorders more common
arthritis more common - knee
Diagnosing lyme
paired blood and CSF serology
EM
PCR synovial fluid
ACA and lymphocytoma and high serology titres
Treating lyme
oral doxycycline/amoxicillin
iv ceftriaxone
21 days or 28 days in arthritis/ACA
