Zoonoses Flashcards
What is the WHO definition of zoonoses?
Infections that are naturally transmitted between vertebrate animals and humans
Malaria, Schistosomiasis, Oncoceriasis and elephantiasis are NOT zoonoses. Why do these not classify as zoonoses?
Even though they are transmitted from animals, they depend on human host as part of life cycle
What are examples of an anthroponosis (humans infecting animals. ‘Reverse zoonoses’?
> Influenza (virus infecting birds, pigs)
‘Strep throat’ (bacteria affecting dogs)
Leishmaniasis (parasite infecting dogs)
Chytridiomycosis (fungus affecting amphibians)
List some examples of bacterial zoonoses? [7]
- Salmonella
- Campylobacter
- Shigella
- E. coli
- Leptospirosis
- Plague
- Psittacosis
List some examples of viral zoonoses? [4]
- Rabies
- Avian influenza
- Ebola
- West Nile fever
List some examples of parasite zoonoses? [4]
- Toxoplasmosis
- Cysticercosis
- Echinococcosis
- Visceral larva migrans
What are fungal 2 and prion 1 zoonoses?
Fungal
- Dermatophytoses
- Sporotrichosis
Prions
-CJD
What are examples of more common zoonoses in the UK? [5]
- Salmonella
- Campylobacter
- Toxoplasma
- Psittacosis: Chlamydophila psittaci
- Q fever: Coxiella burnetti
- Ringworm
What are examples of rarely seen zoonoses in the UK? [5]
- Rabies
- Bubonic plague
- Tularaemia
- Acute brucellosis
List some emerging zoonoses? (newly evolved/occurred previously but shows increase in incidence/expansion in geographical, host or vector range) [5]
- Avian influenza
- Nipah virus
- Rabies
- Brucellosis
- Monkeypox
What is rabies and how is it transmitted?
What are 4 animals that are involved in its route of transmission
Viral infection (lyssavirus) transmitted via animal bite
Animals include dogs (97%), bats, monkeys, foxes, racoons
What is the incubation period of rabies?
Can be 2 weeks to several months
Rabies travels to brain via peripheral nerves. What does it then cause?
4 points
Death by…
Acute encephalitis
- Malaise, headache and fever
- Progress to mania, lethargy and coma
- Overproduction of saliva and tears
- Can’t swallow and hydrophobia
- Death by resp failure
What is the diagnosis [2] and treatment [4] of Rabies?
Is diagnosis easy/difficult? When is a diagnoses most commonly made in reality?
Diagnosis
- PCR of saliva/CSF
- Difficult, often found on post mortem
Treatment
- Wash wound and immediately give post exposure prophylaxis: even if already previous vaccinated
- If previous immunization, 2 further doses of vaccine
- No previous immunisation, give human rabies immunoglobulin and full course of vaccination, around wound
Full course - 4 doses of rabies vaccine over 14d
Brucellosis causing organisms are excreted in milk, placenta and aborted foetuses of livestock. When can humans become infected? [4]
> During milking infected animals
During parturition
Handling carcasses of infected animals
Consumption of unpasteurized dairy products
Describe the Brucella organisms microscopic appearance
Small, gram negative coccobacilli
Discuss the following about Brucella Melitensis (1st of 3 Brucella organisms)
- Human virulence
- Animal host
- Geographic area
- Most virulent in humans out of 3 organisms
- Goats, sheep and camels are hosts
- Mediterranean area
Discuss the following about Brucella Suis (2nd of 3 Brucella organisms)
- Human virulence
- Animal host
- Geographic area
- Relatively virulent in humans
- Pigs are hosts
- N/S America, SE Asia
Discuss the following about Brucella Abortus (3rd of 3 Brucella organisms)
- Human virulence
- Animal host
- Geographic area
- Least virulent in humans out of 3 organisms
- Cattle, buffalo are hosts
- Worldwide
What is the incubation period of Brucellosis?
5-30 days (up to 6m)
What do you see in an acute presentation of Brucellosis? (lasts 1-3 weeks) [4]
- High ‘undulant’ fever
- Weakness, headaches
- Drenching sweats
- Splenomegaly
What do you see in a subacute presentation of Brucellosis? (>1m) [2]
- Fever
- Joint pains (knee, hip, back)
What do you see in a chronic presentation of Brucellosis? (months/years) [5]
- Flu like symptoms, Malaise, Splenomegaly, Chronic arthritis
- Endocarditis
- Depression
- Epididymo-orchitis
- Rarely meningism
In subclinical brucellosis, how many have positive serology?
50%
What is the treatment for Brucellosis? [3]
What would you give in CNS disease?
> Long acting Doxycycline 2-3 months
Rifampicin
IM gentamycin for first weeks
Add cotrimoxazole for 2 weeks in CNS disease
Regarding leptospirosis, what organisms cause it and how is it transmitted? [3]
2 Types
> Leptospira icterohaemorrhagica (fish)
Leptospira hardjo (cattle) is commonest form now
Cattle, fish, rats
What are the leptospirosis symptoms when infected with L. icterohaemorrhagica? [3]
- Flu symptoms
- Jaundice
- Renal failure
What are the leptospirosis symptoms when infected with L. hardjo? [3]
- Fever
- Meningism
- No jaundice
Leptospirosis organisms (spirochaetes) exist in contaminated water, mud and soil. What activities associated with these pose as risk factors? [7]
- Planting
- Hunting
- Gutting
- Canoeing
- Weeding
- Fishing
- Swimming
What contact is needed for humans to be infected? [3]
What is the incubation period?
> direct contact with animal (cattle/fish/rats)
Contact with environment
contaminated with urine
Incubation period 2-30 days (usually 10-14d)
What are the symptoms of Leptospirosis? [4]
- Undifferentiated fever
- Myalgia
- Headaches
- Abd pain
What is the treatment for Leptospirosis? [3]
- Doxycycline for mild disesase, IV penicillin for severe
- Prompt dialysis
- Mechanical ventilation
Lyme disease - most common pathogen in Europe
What is the causative organism?
By tick:
-Ixodes ricinus (Europe)
Causative organism:
Borrelia burgdorferi
Erythema Migrans presents in 80-90% of Lyme cases. When does it present after bite?
Describe erythema migrans visible appearance
7-30 days after bite
Redness spreads and clears in middle forming a ring
Acrodermatitis Chronica Atroficans presents in the late stage of Lyme disease. How does it present? Visible appearance Duration, progression Associated sx [1] Sites
> Bluish-red discolouration: progresses over months to years to atrophic phase
Peripheral neuropathy common
Extensor surfaces of distal extremities
Lymphocytoma is more common in children than adults in Lyme sufferers. How does it present?
Bluish solitary painless nodule on earlobe or areola
Neuroborreliosis presents in around 15% Lyme sufferers. How does it present? [3]
When does it present
> 2-6 weeks after bite
Facial nerve palsy
Radicular pain
Lymphocytic meningitis
In America, what symptoms present more often in Lyme borreliosis?
Cardiac disorders (8-10%): Carditis, heart block
Arthritis (large joints, often knees)
How do you diagnose Lyme disease? [3]
> Erythema Migrans a clinical diagnosis
ACA plus lymphocytoma clinical and high serology titres
Arthritis v high serology titres from synovial fluid. PCR
What is the treatment of Lyme disease?
EM - 2 options, duration of course
ACA - 3 options, dose and timing
LNB - Lyme Neuroborrealiosis
Disseminated infection
EM
>Oral doxycycline/Amoxicillin 2 weeks
ACA
> PcV 2g TDS or amoxicillin
> or Doxy 200mg OD 3/52
LNB
> Doxy 200 mg OD 10-14 days
> OR IV Ceftriaxone
Disseminated infection: ceftriaxone
Toxoplasmosis Pathogen What type of organism is it? Source How is it acquired by humans - 2 ways
Toxoplasma gondii
Protozoan parasite
Cats are the main source
Humans acquire infection from oocysts in cat feces or from trophozoites in undercooked meat e.g. cattle, pigs, horses
Clinical features of toxoplasmosis
3 features of acute form
What is one feature of the acute form which necessitates prompt treatment in pregnant women?
3 clinical signs of chronic form
1 feature in both chronic and acute form [2]
Clinical features:
- Acute form - pneumonia, fever, cough, rash
- Acute infection during pregnancy can be transmitted to baby > congenital malformation
- Chronic form - occipital lymphadenopathy, lymphocytosis, atypical mononuclear cells on blood film
- chorioretinitis, uveitis
Describe congenital form of toxoplasmosis [5]
Hydrocephalus Microphtalmos Microcephaly Convulsions Calcification in brain on x-ray
Toxoplasmosis Ix [2]
What is a positive result and what does it indicate
Which test indicates acute infection
- Sabin Feldman dye test
If positive within 1 month of infection, positive for life - IgM Abs indicate acute infection
Toxoplasmosis
Treatment (although most don’t require treatment)
2 mainstays
2 modes of tx depending on case
sulfonamide + pyrimethamine
folate antagonist
