unit 2: Wildlife Disease Epidemiology

definition of wildlife

refers to individuals whose phenotypes has not been selected by humans, and animals that are not living under human supervision (in captvity etc)

reasons why diseases are now bigger than they used to be

examples of zoonotic diseases stemming from wildlife

-rabies

-ebola

-SARS

-leishmania

-Nipah

-West Nile Virus

zoonotic emergence stage one

agent is only in animals and there is no transmission to humans

zoonotic emergence stage two

primary infection in humans which can only transmit from animals

zoontoic emergence stage three

limited outbreak can be transmitted from animals or a few cycles in humans

zoonotic emergence stage four

long outbreak can be transmitted through animals and humans

zoonotic emergence stage 5

transmission only from humans

How big an issue a disease will be depends on 3 main things

-potential impact

-proximity to other species

-maintained or not

whats important in resolving wildlife diseases

-monitoring and surveillance

-early detection

definition of wildlife health

as the physical, physiological, behavioural and social well-being of free ranging animals measured at an individual, population and wider ecoystem level, and their resilience to change such as habitat loss

why is searching for virus not effeicient

-expensive

-there is many

-have to have detection equptment available

ecohealth aliance USAID

aim to predict the upcoming virus to stop them before they become a public health issue

Diclofenac and vultures

vultures where feasting on infected diclofenac tissue in cattle causing them to die on a mass level nearing extinction

Saiga mass mortality

half the entire species were killed in one month due to The bacterium which was found to be Pasteurella multocida, a microbe normally harmless to Saiga antelopes. What turned the bacterium into a devastatingly lethal version were extreme changes in the environment

climatic link between anthrax related reindeer deaths

the reindeers feed source was reduced and so they were subjected to a smaller feeding areas causing them to dig deeper instead unearthing anthrax

outbreak of bluetongue in the UK- 2007

1st case occured in suffolk and was found to be caused by midges carring the virus being blown over from Belgium due to the windy conditions

why are vector diseases like blue tongue likely to appear in new areas

tempuratures will increase which will cause their habitiat to be more extensive increasing the chances of different populations overlapping spreading the infections not as extreeme as whole populations moving areas

effects of climate change on hosts and their parasites

-behaviour

-development

-fecundity (fertility)

-mortality

examples of effects on climate change at an individual level

lysozyme involved in immune response acts higher at increased temps

effects of pathogen extinction on a community levels

can reduce the disease but also cause pathogenic organisms to increase due to reduced competition

example of effects of climate change on community levels

causes the bleaching of coral which causes mucous prodcuction with less antibiotic properties causing the bacterial community to be dominanetd by Vibrio spp which is more virulent

why is it difficult to design epidemiological studies involving wildlife

-population accessibility and detection

-sampling and handling challenges

-ethical and legal considerations

-ecological complexities

-disease detection and monitoring

-biases e.g. observer and data gaps