EPIDEM: ecology of disease

ecology

ecology

study of animals and plants in relation to their habits and habitation (habitat); it is developed as a discipline relating to animals and plants

distribution and size

Two major factors that determine the occurrence of disease

competition

The currently accepted theory is where populations are brought into balance; it is also density-dependent

moran effect

if two similar populations have the same density-dependent structure then their sizes over these areas may be synchronized

microparasite

when they multiply directly when inside the hosts, increasing the level of parasitism. They include viruses, bacteria and protozoa

macroparasite

they do not increase the level of parasitism; they grow in the host, but multiply by producing infective stages, which are then released from the host to infect new hosts. They include helminths and arthropods

home range

natural restriction to the area over which they roam to undertake normal activities; useful guide to areas over which disease surveillance in wildlife should be conducted

territory

part of an animal’s home range that it defends aggressively from invaders

territoriality

behavioral response where an animal defends aggressively their home range from invaders

peck order

social hierarchy discovered among birds; When crowding occurs, the socially weaker animals are forced out.

intraspecific competition

competition between members of the same species

interspecific competition

when two species live together, in which circumstance they either might both thrive, or one may be exterminated by the other

competitive exclusion

competition will exclude all but one species from a particular position defined by an animal’s feeding habits, physiology, mechanical abilities and behaviour.

sympatric species

species found in the same country or area that avoid competition. Giraffe, Thompson’s gazelles and wildebeests are sympatric species in East Africa.

divergence of character

characters must diverge when closely-related species live in the same region, be it test tube or prairie.

fundamental niche

range of sites that can be occupied by a parasite

realized niche

sites that are actually occupied by a parasite

trophic levels

animals fed at different levels in the food chain

ecosystem

relationship between animals linked by food chains defines the variety of animals in a particular area.

biotope

is the smallest spatial unit providing uniform conditions for life; it can vary in size

biocenosis

is the collection of living organisms in a biotope. The organisms include plants, animals and microorganisms in the biotope. Sometimes biotic community is used synonymously

Landscape

is a term in wide general circulation and therefore can encompass different concepts. In ecology, it is a recognizable and repeated cluster of ecosystems

spot disturbance patches

patches resulting from disturbance of a small area of matrix; patches produced by a small fire in a grassland

remnant patches

patches caused by widespread disturbance surrounding a small area; a shrub-covered island produced by flooding a valley

environmental-resource patches

patches resulting from the normal heterogeneous distribution of resources; concentration of reptiles and amphibians in a desert oasis

introduced patches

patches stemming from introduction by human activity; golf courses, wheat fields

ephemeral patches

patches determined by normal short-lived fluctuations in resources; localized blooming of annual plants in the desert

Autochthonous

derives from the Greek adjective autos, meaning ‘oneself’ or ‘itself’; is one ‘coming from the land itself’. Examples are to be found in biomes such as tropical rain forests and deserts

Anthropurgic

is derived from the Greek noun anthropos, meaning ‘man; is one created by man; Examples are those found in cultivated pastures and towns

Synanthropic

originates from the Greek preposition syn, meaning ‘along with, together with; is one that is in contact with man. An example is a rubbish tip, harbouring a variety of vermin.

ecological climax

traditionally said to have occurred when plants, animals, microbes, soil and macroclimate have evolved to a stable, balanced relationship, and originally was used in relation only to plants

Ecotones

are the transitional boundaries between two adjacent biomes or smaller landscapes, ranging from a few centimetres to a few kilometres; regions where rates of infectious disease may be high;

chronotone

refer to temporal man-made changes in the use of ecosystems occurring over relatively short periods of time

ecological mosaic

is a modified patch of vegetation, created by humans, within a biome that has reached a climax. Infection may spread from wild animals to humans in such circumstances.

landscape epidemiology

study of diseases in relation to the ecosystems

nosogenic territory

An area that has ecological, social and environmental conditions that can support a disease

nosoarea

is a nosogenic territory in which a particular disease is present