34. Epidemiology and prevention of zoonotic protozoon and viral infections

Rabies

Rabies virus is a type of lyssavirus
Epidemiology
- Very few cases in Europe
- Present in all parts of the world
- 95% of death occur in Asia and Africa
Reservoir
- Dogs, bats, wolves, foxes
Transmission:
- Bite or direct contact with saliva of infected animal
- Retrograde transport from nerves at bite site to the CNS
Incubation period
- 1-3 months
- Depends on how far from the CNS the infection occurred
Two types
- Encephalitic rabies (most common)
  - CNS symptoms
  - Agitation
  - Confusion
  - Hypersalivation
- Paralytic rabies
  - Flaccid paralysis spreading from the bite wound
- Both
  - Hydrophobia
Prevention
- Human vaccine
  - For travellers spending much time outdoors
  - For high-risk occupations, like veterinarians
- Oral immunization of animals
  - Releasing baits containing oral vaccine into high-risk areas
  - Vaccination of dogs
- Teaching children to avoid animal bites
- Post-exposure prophylaxis
  - Washing wound for 15 minutes
  - Giving rabies vaccine soon after bite
  - Administration of rabies antibodies if needed

Hantavirus

Hantavirus is a bunyavirus
Reservoir
- Rodents
Transmission
- Inhalation of infected rodent urine or droppings
- Bites
Risk groups
- Forest workers
- Farmers
Clinical features
- Haemorrhagic fever with renal syndrome
- Hantavirus cardiopulmonary syndrome
Prevention
- Avoidance of dust
- Minimizing contact with rodents

Toxoplasmosis

Toxoplasma gondii (a helminth)
Reservoir
- Cats
Transmission
- Ingestion of cysts
- Direct through cat faeces
- Indirect through food or water contaminated with cat faeces
- Pigs, cows can ingest cyst, making their meat infected
Clinical features
- A part of TORCH
- Perinatal death
- Congenital infection
  - Neurocognitive deficit
Prevention
- Avoid contact with cat litter
- Hand hygiene
- Avoid undercooked meat