Zoonoses Flashcards
1
Q
Anthroponoses
A
Diseases obtained from other people (human reservoir)
2
Q
Zoonoses
A
- Infections obtained from animals (indirectly or directly, animal reservoir)
- ~60% of pathogens are zoonotic
- Higher percentage of emerging pathogens are zoonotic
3
Q
Different contact scenarios
A
- Agriculture (farms and livestock)
- Animal product processing and manufacturing
- Forestry, outdoors
- Recreation (pets or wild animals)
- Clinic, labs
- Epidemiology and public health
- Emergency situations
4
Q
Zoonoses is NOT
A
- Poisonings/envenomations
- Bites, kicks, scratches
- Allergies
- Anthroponoses (even with animal derived transportation)
5
Q
What are the cost of zoonotic diseases?
A
- Human Health (loss of productivity and life)
* Economic (prophylaxis and treatment, import/export restrictions, lost trade and tourism)
6
Q
What are the social changes that affect zoonoses?
A
- Changes in small animal ownership (> households with children)
- Changes in the status of animal (Human animal bond. Pets are family as opposed to property)
- Changes in “exotic” animal ownership (has increased)
- Changes in food animal production (increase in percentage of animals per farm)
- Changes in global trade and travel (decreased travel time with a bigger range of travel. Increased trade, especially in exotics)
7
Q
Diversity of zoonoses
A
- 800 different pathogens, covering all taxonomic groups
* Every animal species has zoonotic diseases, some being specific
8
Q
Diverse life cycles of zoonoses
A
- Some can be perpetuated by a single vertebrate specie
- Others require more than a single specie
- Others require a combination
9
Q
Direct routes of transmission
A
- Droplet/aerosol
- Oral (i.e. bite)
- Contact
- Risk elevated with close work with animals
10
Q
Indirect routes of transmission
A
- Food/water borne
- Vector borne
- Fomites
- Risk elevated with exposure to mode of transportation.
11
Q
Pathway of Taenia Solium
A
- Pig eats eggs (porcine cysticercosis) where it ends up in the muscle
- Humans eat the cyst and the adult tapeworm develops in the GI tract (Human taeniasis)
- If it ends up in the brain, it is considered neurocysticercosis (Human cysticercosis)
12
Q
Taenia Solium: Neurocysticercosis
A
- Larvae encyst in the brain, leading to epilepsy, seizures, behavioral changes, and blindness.
- Death in 50-80% without treatment
- Leading cause of epilepsy, seizures in developing worlds
- Albendazole and praziquantel to control seizures
13
Q
Reservoir of Taenia Solium
A
Humans (primary) and pigs (intermediate)
14
Q
Transmission of Taenia Solium to humans
A
Taeniasis •Eating undercooked pork Neurocysticercosis •Self infection • Fecal material from someone who has the tapeworm intestinal infection • Consuming food with the eggs
15
Q
Transmission of Taenia Solium to pigs
A
Contamination of feed, pasture, or water with human feces.
•Fertilizing with untreated human sewage.
•Leakage overflow of human sewage
•People defecating into feed
16
Q
Prevention of Taeniasis
A
- Meat inspection (only 50% of carcasses are detected)
* Proper cooking/handling of pork
17
Q
Prevention of Neurocysticercosis
A
- Block transmission (washing hands after defecation)
- Proper sewage management
- Treat the people with tapeworm
18
Q
Prevention of Swine cysticercosis
A
- Prevent untreated human sewage from being used
* Ensure there is no overflow of sewage
19
Q
Giardia
A
- One host life cycle (consume cysts and trophozites form which produce cysts)
- Many genotypes, can infect many mammals (multiple reservoir species)
20
Q
Transmission of giardia
A
- Consuming cysts
- Water is a common source
- Surface contamination of food
21
Q
Prevention of giardia
A
- Water treatment
- Sewage treatment
- Wash/peel veggies and fruits
22
Q
Rabies
A
- Acute, progressive, encephalomyelitis
* Highest fatality rate of any conventional infectious disease
23
Q
Etiology of rabies
A
•Caused by the RNA virus Rhabdoviridae, genus
Lyssavirus(1)
• At least 11 other lyssavirus species can cause rabies
24
Q
Rabies host
A
- Most, if not all mammals, are susceptible.
- All reservoirs = vector but not all vectors = reservoirs
- Principle reservoirs: carnivora (canids, skunks, raccoons, mongooses) and chiroptera (bats).
25
Transmission of rabies
* Bite of an infected animal
* Virus replicates in muscle near bite
* Virus moves up peripheral nervous system into CNS, up the spinal cord
* Once in the brain, it causes fatal encephalitis
* Virus enters salivary glands/other organs
26
Distribution of rabies
* All continents except Antarctica
* Several areas considered "free" of the disease
* Globalization threatens disease free status
27
Epidemiology of rabies in the Caribbean
* Rabies in the mongoose: Puerto rico, Cuba, Domincan Republic, Grenada
* Rabies in the bat: Cuba, Grenada, and Trinidad
28
Burden of rabies
* ~50,000 human deaths a year (most in developing countries)
* Tens of millions of human exposure
* Domestic dog is the most important reservoir
* Wildlife are important in developed countries
29
Prevention of rabies
* Surveillance of animals and humans
* Reduce animal reservoir (vaccinations and feral control)
* Reduce human risk (post exposure procedures, vaccinations, and education)
30
Rabies in the US
* Human rabies uncommon, but about ~30,000-~38,000 exposure cases a year.
* ~5000-~10,000 animal rabies cases a year
* Dog rabies transmission has been eliminated
* Every state except for Hawaii
31
Hantavirus
* Bunyaviridae: Enveloped ssRNA viruses
* As a genus, distributed world wide (individual species limited to specific hosts and geographic locations)
* Rodents are reservoir (usually wild rodents but can affect pets) and asymptomatic
32
Transmission of Hantavirus
* Shed in urine, saliva, and feces
* Primarily transmission: aerosol (Indirect or direct. Inhalation of urine and feces while sweeping).
* Can survive for weeks, susceptible to desiccation
* Secondary transmission: bite
33
Clinical signs in humans: Hantavirus pulmonary syndrome (HPS)
* "new world" disease
* Starts with fever, chills, myalgia, headache.
* Increased vascular permeability in the lungs.
* Fatal in 40% of cases
34
Clinical signs in humans: Hemorrhagic Fever with Renal Syndrome (HFRS)
* "old world" disease
| * Petechial hemorrhage, renal damage, cardiovascular shock
35
Risk factors of hauntavirus
* Increased rodent density (looking food, warmth)
* People who work close to rodents or rodent habitats
* Prevention includes wearing face masks, gloves
36
Anthrax (Bacillus anthracis)
* Spore forming bacterium that can survive in soil for years
* Usually inhalation of spores in aerosolized soil, eating infected plants, or eating infected animals (most cases seen in cattle)
* Veterinarians can be exposed percutaneously to infected blood
37
Symptoms of cattle anthrax
* Bleeding from all orifices
* Swelling
* Sudden death
38
Postmortem signs of cattle anthrax
* Blood not clotted
* Spores in microscopy
* Rapid bloating
* Lack of rigor mortis
* Blood from orifices
39
Anthrax control
* Vaccinations and education
* No necropsy performed for suspected cases
* Burn the bodies or bury quickly
40
Brucellosis
* Brucella melitensis and abortus are most pathogenic in people.
* Brucella suis and canis are less pathogenic in people.
* “undulant fever” or “Malta fever” or “Bangs Disease”
41
Symptoms of Brucellosis
* Recurring fever that can last for months
* Abortions if pregnant
* Neurologic, endocarditis, possibly chronic fatigue
* Difficult to diagnose
42
Transmission of brucella spp.
* Ingestion, mucous membrane exposure, or percutaneous inoculation (aborted fetus, unpasteurized milk, blood/feces/urine/semen/uterine secretions)
* Rarely infects humans but most cases of veterinarians exposed to contaminated blood.
43
Controlling brucella spp.
* Eliminate animal reservoir
| * Pasteurization of milk and cheese
44
Borreliosis
* Tick transmitted spirochetes
* Potential to cause chronic disease
* Extensive geographical distribution
* Exists primarily in enzootic wildlife cycles but do cross over to domestic animals
45
2 groups of borreliosis that cause zoonotic disease
* Ixodes spp. hard ticks (lyme disease)
| * Soft ticks (relapsing fever)
46
Borrelia burgdorferi (“Lyme disease”)
* Vector: Ixodes spp.
* Reservoir: sylvatic rodents (in southeastern US, also some lizards)
* Affects people, dogs, horses.
* Symptoms include Acute febrile illness, myalgia, sometimes arthralgia
* Chronic disease manifests as cardiovascular, neurological, or joint problems
47
Risk of exposure to lyme disease
* Outdoor activities or having a backyard that include tick habitat.
* Ticks must attach for >48 hours to transmit disease
* If untreated, domesticated dogs can serve as "sources" of infection
48
Lyme disease prevention
* Avoid places with ticks
* Apply tick repellant
* Remove ticks if attached
49
West nile virus
* Genus: Flavivirus
* Maintained in a mosquito-bird-mosquito cycle (stays in birds 1-4 days post exposure)
* Birds infected usually survive but >317 species of dead birds have been found with WNV
50
Transmission of west nile virus
* Primarily though mosquito bites
* Human/horses are dead end hosts
* After infection, life long immunity is developed
* Secondary infection: bloodborne infection, laboratory exposure, and breast milk
* No evidence of infection from handling dead/ill birds
51
Clinical signs of west nile virus in horses
Neurologic: ataxia, hypermetria, weakness, peri- or
| tetraparesis, recumbency, death
52
Clinical signs of west nile virus in humans
* ~80% of people are asymptomatic
* ~20% develop a mild febrile illness
* 1/150 infected develop neuroinvasive disease (10% of cases are fatal)
