Zoonosis Flashcards
what is zoonosis
Infectious diseases transmitted naturally between humans and animals wild or domestic
Enzoonotic in animal reservoirs and transmit to humans with little onward spread- trypanasomiasis, rabies
Originally zoonotic now established human-to-human transmission with no/little ongoing zoonotic transmission - HIV
Both typically causes stably endemic disease with localised outbreaks
Efficient person-to-person spread once transmitted from reservoir - local or global outbreaks - SARS / SARS-CoV-2 / EVD / Pandemic influenza
Typically cause rapidly spreading sizeable outbreaks
what are mechanisms of transmission for zoonotic diseases?
what bacteria, viruses, parasites can be spread zoonotically?
what are common UK zoonosis?
Salmonella
Campylobacter
Toxoplasma
(Psittacosis – Chlamydophila psittaci)
(Q-fever - Coxiella Burnetti)
Ringworm/dermatophytosis
what are uncommon UK zoonosis?
Anthrax
Rabies
Bubonic plague
Tularaemia
Acute brucellosis
what are not zoonosis?
Malaria
Schistosomiasis (Snail fever)
Oncoceriasis (River Blindness)
Elephantiasis (Lymphatic Filariasis)
Because even though transmitted from animals, they depend on the human host for part of their life-cycle
what is anthroponosis?
Reverse zoonoses’ in that humans are infecting animals
Examples are:
Influenza (virus affecting birds, pigs)
‘Strep throat’ (bacteria affecting dogs)
Leishmaniasis (parasite affecting dogs e.g.)
Chytridiomycosis (fungus affecting amphibians)
give examples of anthroponosis?
Influenza (virus affecting birds, pigs)
‘Strep throat’ (bacteria affecting dogs)
Leishmaniasis (parasite affecting dogs e.g.)
Chytridiomycosis (fungus affecting amphibians)
what impact does food security have on zoonoses?
Increasing global meat consumption and production
Global intensification of livestock production
Substandard animal welfare
Inadequate disease surveillance
Increasing consumption of bushmeat
Improper preparation or slaughter - echinococcus, cysticercosis
Many enzoonotic foodbourne pathogens: bovine TB, brucellosis, salmonellosis
Incomplete understanding of pathogen lifecycles
what is one health?
Initial adoption by several global bodies in 1984 with slow implementation
Cross-sectional approach integrating animal-human health
Wide recognition of interaction between the two but little cross sectoral communication
Combining Dx and Mx with disease control and surveillance programs in animals
what is Lyme disease?
clustering of childhood arthritis in Old Lyme, Connecticut, USA in 1977
Burgdorfer found cause in 1982 – hence Borrelia burgdorferi
Spirochaete found in wild deer
Transmitted by tick, Ixodes ricinus
Commonest in summer months
what is the Lyme vector?
Ixodes genus
I. ricinus (Europe)
I. scapularis /pacificus (North America)
I. persulcatus (Asia)
what clinically presents in advanced cases of Lyme’s disease?
erythema migrans
80-90% of cases
Clinical diagnosis
3-90 days after the bite
(7-30)
Single or multiple lesions
what are early and late symptoms of Lyme disease?
what do 15% of Lyme disease patients develop?
App 15% of patients develop NEUROBORRELIOSIS
Triad of facial nerve palsy, radicular pain & lymphocytic meningitis
Radicular pain (70-85%), migratory, worse at night
Cranial neuropathy (app 50%) – facial palsy
Onset of symptoms 2-6 (1-12) weeks after bite
Preceded by EM in 30-50%
what is the treatment for Lyme disease?
Doxycycline
Amoxicillin
what is the treatment for Neuro Lyme?
Ceftriaxone
what is leptospirosis?
spirochete - L. icterohaemorrhagica, L. hardjo
One of the most widespread Zoonosis
Many reservoir host
Survive in the environment for weeks to months
Penetrate abraded skin or mucous membranes and cause systemic illness
what are symptoms of leptospirosis?
Undifferented fever; myalgia, headaches & abdominal pain
Severe disease in 5-15%
Weil’s disease (Triad of jaundice, AKI, bleeding)
Pulmonary haemorrhage (PH)
Case fatality 5-40%, >50% in PH
how does leptospirosis come into contact with humans?
Humans are incidental hosts
Direct contact with the animal
Contact with environment (water) contaminated with their urine
Incubation 2-30 days (10-14)
what investigations are done for leptospirosis?
Clinical high suspicion
Serology – IgM & IgG
Microscopic Agglutination Test
what is the treatment for leptospirosis?
Doxycycline
Amoxicillin or Azithromycin as second line
Severe disease - Ceftriaxone
what is rabies?
Viral Infection (lyssavirus) transmitted from the bite of an infected animal
Wide range of wild animal transmitters:
Dogs (97%), bats
Also monkeys, foxes, racoons, skunks, wolves, cats
Incubation
Typically 1-3 months
May be years
