Lecture 8: Zoonosis Flashcards
what is a zoonotic disease?
- infectious diseases transmitted naturally between humans and animals wild or domestic
how are zoonotic diseases transmitted?
- airborne: transfer of viruses
- vectors: transmitting infected agents from animals
- direct contact with animals e.g. bites from infected animal
- close proximity to animals: faecal oral transfer/animal body fluid in cuts
- food borne: consuming infected meat or milk
list some ‘common; UK zoonosis
- salmonella
- campylobacter
- toxoplasma
- (Psittacosis - Chlamydophilia psittaci)
- (Q-fever - Coxiella Burnetti)
- ringworm/dermatophytosis
list some uncommon UK zoonosis
- anthrax
- rabies
- bubonic plague
- tularaemia
- acute brucellosis
why is: malaria, schistosomiasis (snail fever), oncoceriasis (river blindness), elephanitasis NOT zoonoses?
- because even though transmitted from animals, they depend on the human host for part of their life cycle
what is an anthroponosis?
reverse zoonoses’ in that humans are infecting animals
anthroponosis examples
- influenza (virus affecting birds, pigs)
- strep throat (bacteria affecting dogs)
- Leishmaniasis (parasite affecting dogs)
- Chytridiomycosis (fungus affecting amphibians)
lyme disease definition
- an infectious condition caused by the spriochaete Borrelia burgdorferi, transmitted via the bite of lxodes ticks predomiantly found in wooded areas.
lyme disease epidemiology
The incidence of Lyme disease has been progressively increasing, with a significant proportion of cases originating from the northeastern regions of the USA and northern-eastern Europe.
what are some early symptoms of lyme disease (3-30 days after bite)?
- fever
- chills
- headache
- fatigue
what are some later symptoms/signs of lyme disease?
- facial palsy
- irregular heartbeat
- dizziness
- erythema migrans
describe neuroborreliosis in lyme disease
- approx 15% of patients develop NB
- triad of facial nerve palsy, radicular pain and lymphocytic meningitis
- onset of symptoms 2-6 (1-12) weeks after bite
- preceded by erythema migrans in 30-50%
lyme disease investigations
- is the erythema migrans rash present? If yes diagnose Lyme disease. If no then
- consider ELISA testing
- offer immunoblot test
what antibiotics are used to treat lyme disease?
- doxycycline
- amoxicillin
- ceftriaxone (in the case of neuro lyme)
how is leptospirosis transmitted to humans?
Humans are incidental hosts:
- direct contact with infected animal
- contact with environment (water) contaminated with their urine
what is the incubation period of leptospirosis?
2-30 days (10-14)
symptoms of leptospirosis
- undifferentiated fever
- myalgia
- headaches
- abdominal pain
Severe disease:
- Weil’s disease (triad of jaundice, AKI, bleeding)
- pulmonary haemorrhage (PH)
leptospirosis investigations
- clinical high suspicion
- serology: IgM & IgG
- microscopic agglutination test
leptospirosis treatment
- doxycycline
- amoxicillin or azithromycin as second line
- severe disease: ceftriaxone
features of rabies
- viral infection (lyssavirus) transmitted from the bite of an infected animal
- wide range of wild animal transmitters: dogs (97%), bats, also monketys, foxes, racoons, skunks, wolves, cats
- incubation period typically 1-3 months, may be years
symptoms of rabies: both furious and paralytic
furious (70%):
- hydrophobia
- insomnia
- confusion
- agitation
- coma
paralytic (30%):
- ascending flaccid paralysis
- fever
- confusion
- coma
rabies investigations
- PCR of skin biopsy, saliva
- often post mortem confirmation: brain biopsy
rabies treatment
- nil effective
- Milwaukee protocol
Post exposure:
- fully immunised: 2 doses human rabies immune globulin (HRIG) day 0; day 3-7
- not immunised and immunocompetent: HRIG + 4 doses: 0, 3, 7, 21
- not immunised and immunocompromised: HRIG 5 doses: 0, 3, 7, 14, 30
what is ebola?
a filovirus affecting West and central Africa
what is the ebola incubation period?
2-21 days (average 8-10)
ebola symptoms, both dry and wet
dry:
- fever
- fatigue
- aches and pains
wet:
- vomiting
- diarrhoea
- haemorrhage
ebola investigations
- PCR
- serology: IgM and IgG
ebola treatment
- INZAMEB - 3 monoclonal antibodies
- EBANGA - 1 monoclonal antibody
ebola vaccination types
- ervebo: 1 dose, used during an outbreak
- zabdeno and mvabea: 2 doses (1 of each)
