Zoonoses Flashcards
What are zoonoses (3)
Complex group of diseases
Many pathogenic microorganisms that cause disease/colonise animals
Depends on vertebrate intermediate
INFECTIONS ACQUIRED FROM VERTEBRATE ANIMALS
What is an examples of zoonoses
Babesiosis - animal-tick-human
How are zoonoses transmitted (3)
By direct contact
Indirect contact by vector
Indirect contact through environmental contamination
Give transmission routes for zoonoses (6)
Direct contact Ingestion Inhalation Arthropod intermediates Animal bites RARE - person-to-person via blood transfusion
What are the animal contacts that can give us zoonoses (4)
Pets
Lab animals
Household animals
Wild animals
What is a historic example of a zoonoses that had a huge impact on humans
Bubonic plague -Bacteria = yersinia pestis
Brucella (Pompei, Florence Nightingale)
What are some zoonoses that are transmitted via mechanical transmission (3)
Dysentry
Cholera
Typhoid
What are some arthropod-borne zoonoses (8)
Plague Rickettsia Ehrlichia Anaplasma Relapsing fever Lyme borreliosis Leishmania Arboviruses
What is necessary for vector-bore transmission (3)
Organism must be in the correct place - the blood.
Rapid adaptation from human to arthropod.
Dissemination of parasite
What are some traveler associated zoonotic infection (9)
Malaria Brucellosis Dengue Leishmaniasis Relapsing fever Bubonic plague Rabies Ebola....21 day rule Melioidosis
What zoonotic infections are associated with household pets (10)
Psitticosis Q fever Brucellosis Salmonellosis Bartonella Lyme borreliosis Rickettsia Leishmaniasis Echinococcosis Rabies
What are some infections transmitted from cats (5)
Bartonellosis Leptospirosis Q fever Toxoplasmosis Rabies
What are some infections acquired from dogs (5)
Hydatid disease Leptospirosis Brucellosis Q fever Rabies
What are some infections acquired from birds (6)
Psitticosis Influenza Cryptococcus Infleunza A Poultry-salmonella West Nile virus
What are some infections associated with mice (4)
Hantan viruses
Lyme borreliosis
Ehrlichia
Bartonella
What are some infections associated with rats (5)
Rabies Leptospirosis Lassa fever (VHF) Hantan viruses Plague
What are some infections acquired from small ruminants (4)
Anthrax
Brucellosis
Q fever
Listeria
What are some infections acquired form cattle (7)
Anthrax Leptospirosis Brucellosis Bovine tuberculosis Anaplasmosis Toxoplasmosis Ecoli 0157
What are some infections acquired from swine (6)
Brucellosis Leptospirosis Trichinella Hepatitis E Influenza A Japanese encephalitis
What proportion of new emerging diseases are zoonotic in origin
75%
What percentage of all human infections are zoonoses
58%
What increases risk of zoonotic infections
Crowded, hot, unhygenic conditions
What allows pathogens to cross species barriers
Mixing of multiple hosts allows:
Adaptation of pathogen
Adaptation fo vector
What are some travel related sources of zoonotic infections (3)
Tourism
Livestock/exotic species/pets
Food
What are some contact related sources of zoonitic infections (3)
Food - BSE
Physical contact - changed livestock husbandry, new sports - eco challenges
Environmental - encroachment of natural habitats
What zoonotic infections are associated with recreational activities (7)
Leptospirosis Hepatitis A Giardia Toxoplasmosis Mycobacterium marinum/ulcerans Burkholderia pseudomallei Ecoli
What are some important travel associated exotic infections (2)
Leishmaniasis
Burkholderia pseudomallei
What are some common travel related infections (3)
West Nile Virus in America
Food poisoning (travellers diarrhoea)
Influenza A
What clinical clues point towards zoonoses (8)
Consumption of unpasturised dairy produce
Undercooked meat from infected animals
Eating aborted foetuses (Ecuador)
Crushing umbilical cord of newborn lambs/kids between teeth….
Contact - skin lesions, mucous membranes (slaughter house workers, hunters, vets)
Travel
Exposure - food/water/animals
Bites - fleas/ticks/mosquito/fly - time of day important
E.g. walking on the beach in Greece
Where is Leishmaniasis found (2)
Europe
South America
What is the family of the rabies virus
Rhabdoviruses
What type of virus is rabies
It is a lyssavirus, from rhabdoviruses
What type of virus is vesicular stomatis virus
A vesuculoviris from rhabdoviruses
What do rabies and vesicular stomatis have in common
Both rhabdoviruses
What are rhabdoviruses shaped like
Rod-shaped
What does lyssaviruse describe
Frenzy, fluffy appearance of viruse
What are the clinical features of rabies (4)
Contact with infected animal (dog, bat) - usually through being bitten.
Variable incubation
Slow migration to CNS
Inevitable clinical outcome is death
What is the life cycle of a rabies virus in a racoon (6)
Raccoon is bitten by a rabid animal
Rabies virus enters the raccoon through infected saliva
Rabies virus spreads through the nerves to the spinal cord and brain
The virus incubates in raccoon’s body for approximately 3-12 weeks. The raccoon has no signs of illness during this time.
When it reaches the brain, the virus multiplies rapidly, passes to the salivary glands, and the raccoon begins to show signs of disease.
The infected animal usually dies within 7 days of becoming sick
How many people die from rabies/year worldwide
55,000 worldwide/year
How is rabies diagnosed (5)
IFA for rabies antigen in brain tissue
IFA serial frozen skin sections
Isolation of virus - murine neuroblastoma cells or intracerebral mouse inoculation
RT-PCR (>15% nucleotide difference between rabies variants - 8 genotypes)
Serology - neutralisation tests/ELISA for specific IgM
How is rabies prevented (2)
Rabies vaccine pre-travel/exposure
Rapid access to point exposure vaccine and IgG
What is brucellae
Gram-negative facultative intracellular bacteria
Nine species currently recognised
Different species and biovars (differential host specificity and pathogenicity)
How is brucellosis transmitted (6)
Contact with infected animal/environmental contamination Consumption of infected animal products Respiratory Gastro-intestinal Laboratory acquired infection Bioterrorism
What are the clinical features of brucellosis (6)
Incubation 3-4 weeks (may be up to 7-10 months).
Non-specific onset with complications of osteomyelitis (occasionally meningoencephalitis).
Severely debilitating – often chronic
Culture bone marrow (>90% positive).
Blood cultures (70% positive) need extended incubation!
Serological diagnostic tests.
What is the treatment for brucellosis infection (3)
Prolonged therapy of 4-6 weeks with tetracycline or doxycycline combined with streptomycin.
Oral therapy with doxycycline and rifampicin 8 weeks (WHO)
Above supplemented with amikacin bid 7 days
Where is plague currently a problem (2)
Madagascar
Emerging infection in Kazakhstan
What are the potential vectors for plague (4)
Carried in fleas: Birds Cats Rats Camels
What are the two main subsets of plague (2)
Bubonic plague
Pneumonic plague
How is plague diagnosed (2)
Conventional microbiological methods Molecular methods (e.g. PCR)
How is plague treated (4)
Streptomycin
Doxycycline
Gentamicin
Chloramphenicol - meningitis
What is the vector for relapsing fever
Human body louse
Who are most at risk of louse borne relapsing fever
Young males
What are the early clinical features of lyme borreliosis (2)
Erythema migrans
Non-specific flu-like illness
What is the vector for lyme borreliosis
Ticks
In the UK/Eurpose - ixodes tick
What are the clinical features of early disseminated lyme borreliosis (4)
Secondary erythema migrans
Palsies
Carditis
Srthritis
What are the late clinical features of lyme borreliosis (3)
Arthritis
ACA (acrodermatitis chronicum atrophocans)
Encephalopathy
What is the treatment for lyme borreliosis
Doxyclycline
What are the causes of emerging zoonotic diseases (6)
Global warming Vectors moving/animals migrating habitats changing Wars Population growth, failure of vector control/waste removal Global travel
