Animal diseases may be transmitted by infected water either when used for drinking or when deposited on pastureland during the wet season. Water-borne diseases may be parasitic, viral or bacterial. Parasites such as liver flukes depend on water for the maturation of their larvae. The larvae may be ingested through water intake. Incidence of coccidiosis is higher in wet and marshland areas in the natural state when pastureland may become contaminated from the integration of infected faeces into the soil. Drinking water may become infected by diseased animals, particularly domestic animals kept in close and insanitary conditions. Foot-and-mouth disease as an airborne infection has a higher incidence during wet weather, since this is the means by which the virus descends to ground level. Anthrax as a soil-borne disease may also be water-borne, infected from the soil, and carried by surface drainage.