Zoonosis Flashcards
What is zoonosis?
* By definition zoonosis involves at least ___ hosts and a ______.
* The hosts include:
1. ___________ and
2. one of __________ animal species
two, pathogen, humans, vertebrate
Of pathogens affecting humans,
60% are ?
animal-borne (zoonotic)
Globally, 2.5 billion cases related to zoonotic infections
are recorded, resulting in 2.7 million deaths each year
80% of the source of zoonosis are _____________
mammals
Why are most zoonosis (99%) from domestic animals?
96% of global mammal biomass is human & livestock.
We are more genticlaly related to mammals than fish and amphibians, so this is logical.
How many transmitted by rodents? Bats?
85, 27
Classification of zoonosis based on?
- Etiological agent
- Number of hosts involved
- Direction of transmission
- Route of transmission (air/breath, contact, food, soil, vector, water = 7 Fs)
- Scale of the disease, social panic, & policy-makers priority (pandemic, neglected, or bioterrorism i. e. CDC List A, B & C)
- Government consensus/priority for One-Health approach
- Ecological source for its transmission cycle (aquatic, sylvatic, domestic)
Zoonosis
classification based
on etiological agents
- Prion
- Virus
- Bacteria
- Fungi
- Protozoa
- Cestodes
- Trematodes
- Nematodes
Classification of zoonosis based on direction of transmission
- Anthropozoonoses (animals are main host): animal-to-human
Viruses: Rabies, avian or swine influena, rift valley fever,
Bacteria: anthrax, brucella, leptospira, plague, lyme, tularemia, psittachosis
Parasites: hydatidosis - Zooanthropozonoses (humans are main host): human-to-animal
Ameoba, diphtheria, human
M. tuberculosis from human to parrot, cat or Mokey - Amphixenoses (maintained by both): migrate either direction between animal and humans equally
non-host specific
Salmonella, Staphylococcus, streptococcus,
E.coli
Classification of zoonosis based on number of host
species (maintenance cycles) required for transmission
e.g. Rabies –> in absence of humans, rabies can maintain in env?, same with anthrax.
2. one is serving as final host, the other is serving as an intermediate host where larvae grow. Cattle = intermediate?
3. Invertebrate arthropod; if sit in vertebrate they will die in vertebrate.
4. Need inanimate such as soil
Which pathogens have a high impact on global level?
Plague
Cholera
inflouenza virus
Coronavirus
What are the Three CDC categories of bioterrorism agents:?
- List A: 3 bacteria, 3 viruses, & 1 toxin
- List B: 11 bacteria, 3 viruses, & 3 toxins
- List C: 4 newly emerging viruses
List A - CDC bioterrorism agents?
Causing devastating impact on public health and panic in society, leading to social disruption. This list includes:
1. Anthrax.
- Previously used by terrorists in 2001.
- Cause respiratory, gastrointestinal, or neurological symptoms
- Plague:
- Previously used by terrorists.
- Respiratory and gastrointestinal symptoms - Tularemia:
- Previously used by terrorists.
- Respiratory symptoms - Botulism toxin
- Viral hemorrhagic fevers
- Not used previously by terrorists.
- Neurological and respiratory symptoms
a. Filovirus: Ebola and Murburg
b. Bunyavirus: Crimean-Congo virus
Most bioterrorism
agents target
- respiratory systems
- Nervous system
- Cardiovascular system
List B
- Melioidosis (Burkholderia pseudomallei)
- Glanders (Burkholderia mallei)
- Brucellosis (Brucella species)
- Psittacosis (Chlamydia psittaci)
- Q fever (Coxiella burnetii)
- Typhus fever (Rickettsia prowazekii)
- Viral encephalitis [alphaviruses (e.g., eastern and western equine encephalitis)]
5-7 = vector borne - Toxin:
- Ricin
- Staph. aureus enterotoxin B,
- Epsilon toxin of Clostridium perfringens
- Food threats:
- Salmonella
- Shigella
- E.coli O157
- Water bioterrorism threats:
- Vibrio cholera
- Cryptosporidium
8-10 = food and water borne
List C
We do not know much about them, so they are emerging pathogens. The US government files them under “could be used as bio”
Nipah virus –> Pig Rinderpest, comes from bats
Hantavirus
West Nile Virus (Flavivirus)
Japanese Encephalitis
Observe any morbidity or mortality in these animals, affect public unless you stop the spread. These would be an early warning or indicator that something is wrong.
Classification of zoonosis based
on government priority
Neglected zoonosis diseases become an emerging/re-emerging disease; hence, some of
the neglected zoonosis are now priority for control in a One-Health approach in the USA
1. 27 Neglected (forgotten) zoonosis diseases
2. 8 Zoonotic pathogens of One-Health priority
What are the4 27 neglected zoonoses reported to the CDC in the USA?
Brucella, psitaccosi, trich, lepto, etc (relisren)
U.S. Govt changed their mind about the 27 neglected, and picked the top 8 zoonosis of most concern in the USA with a One-Health significance
Classification of zoonosis based on
animal species & ecological source for
transmission cycle of zoonosis
- Aquatic
- Domestic/urban
- Sylvatic (wildlife)
Fish-borne zoonotic diseases affect mainly fishermen,
aquaculture workers and seafood consumers
Enteric virus = norovirus, Hep A, sapo virius?
Enteric bacteria = enterobateriace, salmonella, e.coli, shigella, vibrio, campylo
Enteric protozoa = giard, crypto
Universally present in vertebrates.
List the Fish-borne zoonotic bacterial diseases
Hand of a farmer with necrotic fasciitis caused by
a Vibrio vulnificus outbreak at his eel farm
Fish handlers at risk
E. rhusiopathiae
has a characteristic
purplish, swollen, painful,
hardened rash known as
erysipeloid…..but Do NOT
produce PUS!
Man with a tender nodule on the
dorsum of his right hand
(‘swimmer granuloma’) caused by
Mycobacterium marinum
Also causes pneumonia?
Diphyllobothrium is the ?
Longest tapeworm in the human intestine. 10m, releases 1 million eggs each day and affects 20 million people globally. We can get this from eating fish.
- Cestodes:
Diphyllobothrium is the most important
fish-borne zoonosis caused by a cestode
(tapeworm) parasite, affecting 20 million
people globally
The adult tape worm can reach >10 m in
length, with more than 3,000 proglottids.
Immature eggs are discharged from the
proglottids (up to 1,000,000 eggs per
day per worm)
Fishborne zoonotic parasites of humans?
- cestodes - Diphyllobothrium
- Nematodes: Anisakis
- Trematodes:
>45 million persons globally are
infected with fish-borne zoonotic
trematodes.
The life cycle of trematodes
depends on three types of hosts;
- Trematodes:
- primary snail hosts,
- secondary fish hosts,
- definitive hosts like humans,
dogs or fish-eating birds
Opisthorchis & Clonorchis liver flukes
= LIVER CANCER
Reptiles are a natural reservoir with very high prevalence of ____________.
Reptiles have relatively high contribution
to human infections, especially in _______.
Salmonella, children
Mosquito-borne vial zoonosis
- Zika
- EEE
- Western Equine Encephalitis
- West Nile Virus
2-4 –> bite from Culex mosquito –> brain eating viruses
Bacte4rial zoonosis
. Salmonella
2. E. coli
3. Campylobacter
4. Aeromonas
5. Rickettsia sp.:
bite of mites or ticks from snake, lizard, tortoises
6. Anaplasma phagocytophilum:
bite of ticks from infected lizard
7. Borellia:
bite of ticks from infected lizard, tortoises, snake
8. Coxiella:
bite of ticks from infected lizard, snake
9. Ehrlichia:
bite of ticks from infected lizard
Protozoa zoonosis
- Cryptosporidium
- Giardia
- Leishmania:
bite of sand flies from
lizards
Zoonotic worms that come from birds?
Avian-borne zoonosis
Avian influenza
Coronavirus (SARS)
* Chikungunya
Japanese encephalitis virus
Eastern equine encephalitis virus
* West Nile virus
New Castle disease
etc
Avian-borne bacterial zoonosis
Salmonella
Campylobacter
E. coli
Pasteurella multocida
Yersinia enterocolitica
Mycobacterium avium –> TB
Psittacosis
etc
Particularly in egg - why?
Fecal material on the outside of the egg.
Contact with
nasal secretion:
Chlamydia psittaci
Transmit psittacosis
Pasteurella multocida
Fungus from birds
- Cryptococcus
neoformans:
contact with feces of
infected pigeons and
starlings - Histoplasma
capsulatum:
breath of infected pigeon
or bat feces
Protozoa from birds?
- Cryptosporidium:
contact with feces of
infected birds or foodborne
by ingestion under cooked
meat and eggs
Pet-borne zoonotic parasites
toxocara is a roundworm, nematode. Larave penetrate our skin and cause cutaneous larva migrans
Pet-borne vector-borne zoonotic disease
Bite of dogs transmits
90% of rabies
Pet-borne zoonosis transmission routes to humans
Rabies, echino, barto –> severe if happens
Important livestock & poultry-borne zoonosis of humans
Bovine TB, chlamydia, listeria, Q fever –> humans
Pig trich, swine, Hep E, etc –> humans
Horses:
How many serotypes of Salmonella exist?
2500 different serotypes
of Salmonella have been recognized
Salmonella bacteria are widespread
in the:
1. environment and
2. Animals` gastrointestinal
tract:
fish
amphibians
reptiles,
birds,
mammals
What is the role of wildlife, rodents, bats, wild birds, their movements & their contacts with humans (e. g. bush meat) in zoonosis
Avian influenza
Pandemic in 2004. Miratory birds brought this influenza to poultry industry in asia and then this came to the public. resulting in 20 billion USD losses.
Bovine TB in UK, badger are a reservoir –> cattle industry –> humans; killed all of the cows and the badgers costing 15 billion
Ebola come from monkey, chimp, bat –> humans
MERS , Nipah, corona
Rodent viruses
Rodent bacteria
Zoonosis classification
based on
transmission routes
AKA 7 F’s
Animal bites/scratches/licks
transmit zoonosis
Reducing the risk of pet-associated zoonotic infections
1. Rabies – causes agitation, anxiety, confusion, hallucination, and hydrophobia
2. Pasteurella multocida – cause wound infection of soft tissues and gangrene
3. Bartonella henselae - a facultative intracellular microbe of red blood cells.
In the USA, bartenellosis is more common in under the age of 20
Zoonosis transmitted by damaged skin?
Anthrax
Erysipelothryx
Pasteurella
Route of transmission of zoonotic pathogens
- Direct contact &
- Food-borne
Both routes are the two major
transmission highways of
zoonosis from animals to humans
A single pathogen
uses multiple routes
Zoonotic disease control
Control of zoonotic diseases
. Eliminate zoonosis by eliminating its source
– mass culling/killing then burning animals
- Culling reservoir animals for zoonosis to control at its source
1. Culling 50,000 goats in The Netherlands – to control Q fever
2. Culling 35,000 badgers in UK – to control bovine TB
3. Culling over 4 million cattle in UK – to control BSE (‘mad cow’ disease)
4. Killed and burnt 6.5 million food animals in UK - to control FMD in 2001 (technically a zoonosis but difficult for us to get so he said it isn;t)
Rather mass culling/killing, selectively remove the infected individual animals
* Removal of infected individual can be accomplished in three ways, namely
1. Test and slaughter/cull infected animals – successfully eliminated brucellosis, tuberculosis, glanders, dourine
2. Test, isolate, and treat infected individual animals by drug –
3. Isolate the entire herd (also called quarantine) that may have been exposed to a source of infection for the longest
incubation period of the diseases in question –
Trepanosome –> transmitted via sex in equids
Rather than mass culling/killing or mass medication,
mass vaccination of animals against zoonosis. How?
Q fever –> 20 km
Mycobacterium –> 10 km
How much proportion of animals in the population
be vaccinated to control zoonosis?
Licensed animal vaccines have double function:
immunization of animals reduces zoonotic disease transmission to human
Vaccination or medication of humans to protect them from zoonosis
How to 5. Break/control the transmission routes of zoonosis
Minimize unnecessary
intensive contact with
animals whose health
condition is not tested
Children
Pregnant
elderly
immune-compromised humans
