Ticks are small arachnids from the order of Ixodida. With mites, they make up the subclass Acarina. Ticks are ectoparasites (external parasites), living on the blood of mammals, birds, and sometimes reptiles and amphibians. Ticks are carriers of a number of diseases,
- Lyme disease
- Q fever (rare; commonly transmitted by infected excreta – human waste matter)
- Colorado tick fever, Rocky Mountain spotted fever
- African tick bite fever
- Tick-borne relapsing fever
- Tick paralysis
- Tick-borne meningoencephalitis
- Bovine anaplasmosis
Carriers are organisms that provide a pathway for a pathogen to be transmitted between animals and humans or other animals. Normally, these transfer organisms provide this transport by the means of blood-sucking (ingest the bacteria/virus/parasite from the infected host during feeding and then inject it into another organism while feeding once again). The carrier shows some immunity to the pathogen, allowing for the successful transport of the disease.
These species are distributed around the world. They tend to flourish more in countries with warm, humid climates, because they require moisture in the air in order to undergo metamorphosis, and because low temperatures inhibit their development from egg to larva. Ticks on domestic animals are common and varied in tropical countries, where they cause considerable harm to livestock by transmission of many species of pathogens and also causing direct parasitic damage.
For an ecosystem to support ticks, it must satisfy two requirements:
- There must be a high enough population density of host species in the area
- There must be high enough humidity for ticks to remain hydrated.
Due to their role in transmitting Lyme disease, ixodid ticks, have been studied using geographic information systems (GIS), in order to develop predictive models for ideal tick habitats. According to these studies, it was determined that certain features of a given micro-climate – such as sandy soil, hardwood trees, rivers, and the presence of deer – are good predictors of dense tick populations.