Zoonoses Flashcards
Agents of infectious disease
Parasites Bacteria Fungi Viruses Prions
Zoonotic disease examples
Plague
Salmonella
Taeniasis (tapeworm)
Zoonoses
Diseases and infections which are naturally transmitted from vertebrates and humans and vice-versa
“Diseases and infections”
Diseases caused by animals which are not infected -bites, venom, allergy
“Naturally”
Experimental transmission
“Transmitted”
Shared diseases
Botulism, rickets
“Vertebrates”
If only arthropods involved in cycle- not zoonosis
“Vice-versa”
Animal to human and human to animal
Sometimes never seen in real life (rabies)
Anthropo-zoonoses
From humans to animals
Saprozoonoses
Vertebrate + environment
In sapronosis or geonosis there is disease resulting from a causative agent present in an all natural source, such as soil and water
Food-borne infections and zoonoses
Some food-borne: no vice-versa, no vertebrate
Not all food-borne infections are zoonoses (Hep A)
Some zoonoses are food-borne diseases (Anthrax)
Not zoonosis anymore
HIV- had zoonotic origin, but no more transmission
SIV–> HIV
Percent of pathogens zoonotic
60%
Emerging Zoonosis
A zoonosis that is newly recognized or newly evolved, or that has occurred previously but shows an increase in incidence or expansion in geographical, host or vector range
Emerging Infectious Diseases
Diseases whose incidence in humans has increased in the past 2 decades or threaten to increase in the future
Current emerging zoonoses
Ebola Echinococcosis Dog rabies Avian flu BSE Brucellosis
Importance of zoonosis
More than 800 diseases mutually transmitted
At least 61% of all pathogens of human beings
75% of all emerging pathogens during the past decade
Who is at risk
General population
- children younger than 5
- adults older than 65
- people with weakened immune systems
Exposure: Agriculture
Farmer or other people in close contact with livestock or their products
Exposure: Animal product processing and manufacture
Personnel of abattoirs and processing plants
Exposure: Forestry, outdoors
Persons frequenting wild habitats for professional pr recreational reasons
Exposure: Recreation
Persons in contact with pets and/or wild animals in urban encironment
Exposure: Clinics, labs
Health personnel and other health workers (including lab) who handle specimens, organs, corpses
Exposure: Epidemiology
Public health professionals who do field research
Exposure: Emergency
People affected by catastrophes, refugees, or people temporarily living in crowded or highly stressful situations
Severity of zoonoses
Some are almost always deadly (rabies)
Some severe
Mild/moderate (foot and mouth disease)
Some severe due to numbers
Clinical signs
Human: sick
Animal: no signs
- chlamydia psittaci
Human: sick
Animal: sick
— Rabies
Human sick:
Animal: no signs
–TB
RNA viruses
no proofreading mechanism Each cycle: great number of genetic variant Unable to reproduce Extend of host range Zoonoses Measles, mumps are not not zoonotic
DNA viruses
DNA polymerase proofreading mechanism
Greater genetic stability
Restricting host range
Poxviruses and some herpesvirus
Bacterial zoonoses
All tranmission route (bites/scratch, inhalation, food, vectors, soil and water)
Problem of antimicrobial resistance
Risk for veterinarian: hundreds of bacteria in the oral cavity
Parasitic zoonoses
Various cycles: human can be final, intermediate or paratenic host Multiple types of agents: -protozoa -Helminths (nematodes) -Acanthocephala
Prion zoonoses
Proteinaceous infectious particles
Infectious protein
Long incubation (several years)
Always fatal: neurodegeneration
Animal prion: bocine spongiform encephalopathy
Human prion: new varient creutzfeld-jacob (not zoonoses)
Fungus Zoonoses
Dermatophytoses/Ringworm: Keratinophilic fungi
Case 1: Lyme disease
Agent: Borrelia burgdorferi
Transmission route: Indirect by vector, the hard tick
The most important reservoirs are rodents
It is reportable to the CDC
Case 2: Brucellosis
It is a bacteria, Brucella
Transmission sources are multiples, direct, indirect by fomites or vehicle
The most important reservoir is cattle. Goats are the reservoir for B. melitensis, the most pathogenic species
In the US you have to notify to both CDC and USD, it is a bioterrorism agent category B
Case 3: Sin nombre
It is a Bunyaviridae (RNA) virus
It produces the hantavirus pulmonary syndrome (HPS)
The main transmission route is either direct or indirect through fomites or vehicles, for example, feces in dust
The most important reservoir are rodents
It is a notifiable disease in the US, to the CDC (bioterrorism Agent cat. C)
