Diseases Transmitted by Animals and Insects Flashcards
What are zoonoses?
Infections that occur in both animals and humans
What is direct transmission between animals and humans?
Transmission by direct animal human contact
What is indirect transmission between animals and humans?
Transmission involved a vector
Name three common vectors.
Mosquito
Tick
Flea
Why is it difficult to control zoonoses?
Because they have a complex infection cycle
How can the susceptibility of a host be controlled?
With drug treatment and vaccination
How can wild animals be controlled?
Population control
Vaccination
How can vector populations be controlled?
Habitat changes
Pesticides
How is anthrax transmitted?
By inhalation of spores or direct animal contact
What are the hosts of anthrax?
Cattle
Goat
Sheep
How is bovine tuberculosis transmitted?
Through milk
What is the main host of bovine tuberculosis?
Cattle
What microbe is plague caused by?
Yersinia pestis
What are the two main features of yersinia pestis?
Gram negative bacteria
Facultative anaerobic
How is plague transmitted?
By fleas
In what animals is plague most common?
Wild rodents
What does the bacteria of plague do if it is not killed by neutrophils?
Kills macrophages
Multiply
New bacteria released is resistant to neutrophils
Where does plague spread within the body and what does it cause?
Through the lymphatic system
Lymph nodes become swollen and hemorrhagic = bubonic plague
Where may bacteria spread to in bubonic plague?
The blood = bacteraemia
What do the endotoxins released by bubonic plague bacteria result in?
Systemic shock
Liver damage
Respiratory disease
When does bubonic plague become pneumonic plague?
When bacteria in the blood infects organs
What transmission route does pneumonic plague take when spreading to other animals?
Respiratory
What are the treatment drugs for plague?
Streptomyosin
Tetracycline
What is the incubation period of plague?
1-7 days
What are the two main protozoa that cause malaria?
Plasmodium vivax
Plasmodium falciparum
What vector transmits malaria?
Female anopheles mosquito
What is the cycle of infection of malaria?
- Transmission by mosquito bite
- Sporozoites removed from blood and enter liver
- Formation of merozoites
- Merozoites reproduce and infect red blood cells
- Production of gametes
- Different mosquito feeds on the same human and is infected
- Maturation and fertilisation of gametes in new mosquito
- Growth
- Development and release of new sporozoites
What are the treatments for malaria?
Quinine = kills sporozoites Chloroquine = acts within red blood cells Primaquine = acts outside red blood cells
How can transmission of malaria be controlled?
Eliminate habitats
Eliminate mosquito
Personal protection
Why might some individuals be resistant to malaria?
As a result of polymorphisms
- Altered haemoglobin
What type of microbe causes rabies?
RNA virus
How is rabies transmitted?
Directly
Where does replication of the virus occur?
At the site of inoculation
What is the incubation time for rabies?
1 week to 9 months
Where does replication of rabies viruses inevitably occur?
In the brain
- Hypothalamus
- Thalamus
What are the non-specific symptoms of rabies?
Malaise
Nausea
Sore throat
Fever
What are the neurological symptoms of rabies?
Dilation of pupils
Excessive salivation
Throat spasms
What is the treatment for rabies?
Vaccination after infection
- Inactivated and attenuated
What are rickettsia?
Small obligate intracellular bacteria
What are the two main groups of rickettsia?
Typhus group
Spotted fever group
What is spotted fever?
Necrosis of tissue as a result of rickettsia replicating at the site of a tick bite
How do spotted fever bacteria spread?
Systemically and invade endothelial cells of blood vessels causing haemorrhaging and rashing
