Ticks are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. The timing of the origin of ticks is uncertain, though the oldest known tick fossils are from the Cretaceous period, around 100 million years old. Ticks are widely distributed around the world, especially in warm, humid climates.
Tick-borne diseases, which afflict humans and other animals, are caused by infectious agents transmitted by tick bites. They are caused by infection with a variety of pathogens, including rickettsia and other types of bacteria, viruses, and protozoa. The economic impact of tick-borne diseases is considered to be substantial in humans, and tick-borne diseases are estimated to affect ~80 % of cattle worldwide.
Babesia, also called Nuttallia, is an apicomplexan parasite that infects red blood cells and is transmitted by ticks. Originally discovered by the Romanian bacteriologist Victor Babeș in 1888, over 100 species of Babesia have since been identified.
Anaplasmosis is a tick-borne disease affecting ruminants, dogs, and horses, and is caused by Anaplasma bacteria. Anaplasmosis is an infectious but not contagious disease. Anaplasmosis can be transmitted through mechanical and biological vector processes. Anaplasmosis can also be referred to as "yellow bag" or "yellow fever" because the infected animal can develop a jaundiced look. Other signs of infection include weight loss, diarrhea, paleness of the skin, aggressive behavior, and high fever.
Amblyomma is a genus of hard ticks. Some are disease vectors, for example the Rocky Mountain spotted fever in Brazil or ehrlichiosis in the United States.
East Coast fever, also known as theileriosis, is a disease of cattle which occurs in Africa and is caused by the protozoan parasite Theileria parva. The primary vector which spreads T. parva between cattle is a tick, Rhipicephalus appendiculatus. East Coast fever is of major economic importance to livestock farmers in Africa, killing at least one million cattle each year. The disease occurs in Burundi, Democratic Republic of Congo, Kenya, Malawi, Mozambique, Rwanda, South Sudan, Tanzania, Uganda, Zimbabwe, Zambia. In 2003, East Coast fever was introduced to Comoros by cattle imported from Tanzania. It has been eradicated in South Africa.
Heartwater is a tick-borne rickettsial disease. The name is derived from the fact that fluid can collect around the heart or in the lungs of infected animals. It is caused by Ehrlichia ruminantium - an intracellular Gram-negative coccal bacterium. The disease is spread by various Amblyomma ticks, and has a large economic impact on cattle production in affected areas. There are four documented manifestations of the disease, these are acute, peracute, subacute, and a mild form known as heartwater fever. There are reports of zoonotic infections of humans by E. ruminantium, similar to other Ehrlichia species, such as those that cause human ehrlichiosis.
Ehrlichia chaffeensis is an obligate intracellular, Gram-negative species of Rickettsiales bacteria. It is a zoonotic pathogen transmitted to humans by the lone star tick. It is the causative agent of human monocytic ehrlichiosis.
The Asian blue tick is an economically important tick that parasitises a variety of livestock species especially cattle, on which it is the most economically significant ectoparasite in the world. It is known as the Australian cattle tick, southern cattle tick, Cuban tick, Madagascar blue tick, and Puerto Rican Texas fever tick.
African tick bite fever (ATBF) is a bacterial infection spread by the bite of a tick. Symptoms may include fever, headache, muscle pain, and a rash. At the site of the bite there is typically a red skin sore with a dark center. The onset of symptoms usually occurs 4–10 days after the bite. Complications are rare but may include joint inflammation. Some people do not develop symptoms.
Margaritaria discoidea is a tree in the family Phyllanthaceae, commonly known as the pheasant-berry, egossa red pear or bushveld peacock-berry. These trees are native to the warmer, higher rainfall areas of Africa.
Haematoxenus is a genus of parasitic alveolates of the phylum Apicomplexa.
Haller's organ is a complex sensory organ possessed by hard and soft ticks. Not found outside of Acari, it is proposed to function like the chemosensation of insect antennae, but is structurally different. Ticks, being obligate parasites, must find a host in order to survive. Bloodmeals are necessary for completion of the life cycle, including reproduction and ontogenetic development. First described in 1881, it was named for its discoverer, Haller. While Haller initially proposed it was involved in auditory sensation, this was rejected in favor of olfactory sensation by 1905. This theory was supported by Lee's behavioral studies as early as 1948.
Ticks of domestic animals directly cause poor health and loss of production to their hosts. Ticks also transmit numerous kinds of viruses, bacteria, and protozoa between domestic animals. These microbes cause diseases which can be severely debilitating or fatal to domestic animals, and may also affect humans. Ticks are especially important to domestic animals in tropical and subtropical countries, where the warm climate enables many species to flourish. Also, the large populations of wild animals in warm countries provide a reservoir of ticks and infective microbes that spread to domestic animals. Farmers of livestock animals use many methods to control ticks, and related treatments are used to reduce infestation of companion animals.
Mites that infest and parasitize domestic animals cause disease and loss of production. Mites are small invertebrates, most of which are free living but some are parasitic. Mites are similar to ticks and both comprise the order Acari in the phylum Arthropoda. Mites are highly varied and their classification is complex; a simple grouping is used in this introductory article. Vernacular terms to describe diseases caused by mites include scab, mange, and scabies. Mites and ticks have substantially different biology from, and are classed separately from, insects. Mites of domestic animals cause important types of skin disease, and some mites infest other organs. Diagnosis of mite infestations can be difficult because of the small size of most mites, but understanding how mites are adapted to feed within the structure of the skin is useful.
Mites are small crawling animals related to ticks and spiders. Most mites are free-living and harmless. Other mites are parasitic, and those that infest livestock animals cause many diseases that are widespread, reduce production and profit for farmers, and are expensive to control.
Patricia (Pat) Anne Nuttall, OBE is a British virologist and acarologist known for her research on tick-borne diseases. Her discoveries include the fact that pathogens can be transmitted between vectors feeding on a host without being detectable in the host's blood. She is also a science administrator who served as the director of the Natural Environment Research Council (NERC) Centre for Ecology & Hydrology (2001–11). As of 2015, she is professor of arbovirology in the Department of Zoology of the University of Oxford.
Hyalomma dromedarii is a species of hard-bodied ticks belonging to the family Ixodidae.
Ornithodoros savignyi, known as sand tampan, African eyed tampan or Kalahari sand tampan, is one of some 37 species in the genus Ornithodoros and is a soft tick with a leathery, mammillated integument, causing paralysis and tampan toxicosis, two unrelated conditions. The sand tampan is an ectoparasite on humans, their livestock and wild animals, including birds and bats. Occurring in semi-desert areas of Africa, Saudi Arabia and other parts of the Persian Gulf, India, Sri Lanka and into Asia, it is able to survive for lengthy periods without feeding, spending most of its life burrowed under sand or loose soil, often in wait for animals that rest or sleep under trees or in the lee of rocks, but also in places where people or their animals congregate such as marketplaces, places of worship, cattle kraals and village squares. The timing of its activity is geared to coincide with that of potential hosts, but hot sunny conditions are usually avoided. Because of its habit of feeding and dropping from its host, adult dispersal is limited, whereas larvae may remain attached to their hosts for several days. During its life cycle it will feed on multiple hosts between moults.
Many species of flies of the two-winged type, Order Diptera, such as mosquitoes, horse-flies, blow-flies and warble-flies, cause direct parasitic disease to domestic animals, and transmit organisms that cause diseases. These infestations and infections cause distress to companion animals, and in livestock industry the financial costs of these diseases are high. These problems occur wherever domestic animals are reared. This article provides an overview of parasitic flies from a veterinary perspective, with emphasis on the disease-causing relationships between these flies and their host animals. The article is organized following the taxonomic hierarchy of these flies in the phylum Arthropoda, order Insecta. Families and genera of dipteran flies are emphasized rather than many individual species. Disease caused by the feeding activity of the flies is described here under parasitic disease. Disease caused by small pathogenic organisms that pass from the flies to domestic animals is described here under transmitted organisms; prominent examples are provided from the many species.
