midterm II wobeser environment Flashcards
what are the two factors of the environment?
abiotic factors and biotic factors
what are examples of abiotic factors of the environment?
climate, weather (temp, precipitation, solar radiation, wind), topography, soils/bedrock, water
why are non-living features important for understanding disease?
because the abiotic factors largely determine what biotic factors occur such as what plants or animals are present; they also are important in determining how long disease agents can persist outside of the host; they can also form part of the mechanism by which a disease is transmitted (e.g water-borne, long range air-borne) or they can present geophysical barriers to transmission (such as mountains or highways) that animals will not pass
what are examples of biotic factors of an environment?
plants, vegetation, animals of same species, animals of different species that are (hosts of disease, vectors, competitors, stressors, predators–predators might actually reduce the incidence of disease by killing the sick); humans, other disease agents–as these may predispose animal to getting another disease
what is the ecological niche of a disease?
it is the sum total of its relationship with the biotic and abiotic elements of its environment, AKA what it needs to survive!
why is important to understand the ecological niche of a disease?
because it can help determine what is necessary for the disease and thus how to control it; knowing the niche allows one to modify these factors to prevent disease occurance OR to predict where else a disease might occur and prevent its introduction
what is the example with the moose in Russia dying of liver fluke infection and what does it demonstrate?
this is an example where knowing the ecological niche of the liver fluke helps decrease disease occurance: the fact that snails are needed as an intermediate host was used to dig new water holes in peat areas, where it was two acidic for snails; this reduced transmission
what is one way to determine the important environmental factors for a disease?
identify features that are different between sites and where the disease occurs and the sites where the disease does not occur
how can knowing ecological information about animals help in disease management (e.g pigs in australia)
knowing the ecology of the wild pigs in Australia allows one to make more educated conclusions about how many animals have to be culled because it is known that they are sedentary and remain near water so if a disease was established in wild pigs, the spread would likely not occur over large distances quickly
what is mycobacterium bovis?
it causes bovine tuberculosis and is also found in deer; it has a very broad potential host range and can likely infect any warm-blooded vertebrate; it is shed in secretions, (saliva, nasal) and excretions to some extend). it can persist for days to months outside the body (depending on abiotic factors; sunlight, temp, moisture, pH, and its location: soil, water, feedstuffs, air)
what are the common hosts of mycobacterium bovis in michigan?
black bear, bobcat, coyote, raccoon, red fox, virginia opossum, white-tailed dear, elk, cattle
what is a maintenance host?
it is a host in which the disease can persist indefinitely by transmission within the species
what is a spillover host?
it is a host that can transmit the disease, but the diseae does not persist without introductions from outside the species (e.g. dogs for rabies)
what is a dead end host?
it is a species that can be infected but does not transmit the disease (e.g. human for rabies)
why is important to know if a species is a maintenance, spillover or dead-end host?
because you want to target the maintenance host for the most effective disease control
