Mild winters with an early spring often result in a high number of ticks and an increased frequency of the diseases they transmit. Outbreaks of tick-related illnesses follow seasonal patterns (about April to September in the U.S.) as ticks evolve from larvae to adults. Heartland viral disease - Amblyomma americanum or lone star tick (hard tick) - new viral disease discovered in 2012 in South/Central U.S.African cattle disease - Rhipicephalus evertsi also known as red ticks - vector for parasites or bacterial infections in cattle.Q fever - Rhipicephalus sanguineus, Dermacentor andersoni, and Amblyomma americanum (all three are hard ticks) - vectors for Coxiella burnetii, a bacterium.Powassan encephalitis - Ixodes species and Dermacentor andersoni (both hard ticks) - vectors for Powassan encephalitis virus, an RNA arbovirus.Colorado tick fever - Dermacentor andersoni (hard tick) - vectors for Coltivirus, an RNA virus.Anaplasmosis (human granulocytic anaplasmosis or HGA) - Ixodes species (hard tick) - vectors for Anaplasma phagocytophilum bacteria.Tularemia - Dermacentor variabilis (American dog tick) (hard tick) and Amblyomma americanum or lone star tick (hard tick) - vectors for Francisella tularensis bacteria.Tick-borne relapsing fever - Ornithodoros moubata or African tick (soft tick) - vectors for Borrelia species of bacteria.Centers for Disease Control and Prevention (CDC) some researchers suggest Borrelia lonestari may be the infectious agent. Southern tick-associated rash illness (STARI) - Amblyomma americanum or lone star tick (hard tick) - infectious agent not yet identified according to U.S.Rocky Mountain spotted fever - Dermacentor variabilis (American dog tick) and Rocky Mountain wood tick ( Dermacentor andersoni) (hard tick) are the primary vectors and occasionally the brown dog tick ( Rhipicephalus sanguineus) Amblyomma cajennense (hard tick) is the vector in countries south of the United States - vectors for Rickettsia bacteria.Ehrlichiosis - Amblyomma americanum or lone star ticks (hard ticks) - vectors for Ehrlichia chaffeensis and Ehrlichia ewingii bacterial species.Babesiosis - Ixodes species (hard ticks) - vectors for Babesia, a protozoan.Lyme disease (borreliosis) - Ixodes species (also known as black-legged ticks) including deer ticks (hard ticks) - vectors for Borrelia species of bacteria (a spirochete or spiral-shaped bacterium).The following is a list of tick-borne diseases that may be found in the U.S., the usual tick vector(s), and the organism responsible for the disease that the tick transmits: The stages are part of the life cycle of ticks the smallest stages, larva and nymph, are sometimes generally referred to as "seed ticks" because they resemble small plant seeds. Figure 1 shows several hard ticks and the various stages in their life cycle. Disease transmission usually occurs near the end of a meal, as the tick becomes full of blood. The hard ticks tend to attach and feed for hours to days. Hard ticks have a tough back plate or scutum that defines their appearance. Two families of ticks, Ixodidae (hard ticks) and Argasidae (soft ticks), are important to humans because of the diseases or illnesses they can transmit or cause. If it is possible to bring into the doctor's office what has caused a "bite," the physician may be able to determine what potential vector caused the "bite." ![]() Some common examples are mosquitoes, bedbugs and fleas (these are insects, not arthropods). Many organisms that bite humans for a blood meal are not ticks and should not be confused with ticks. There are more than 800 species of ticks throughout the world. Ticks (and mites) are arthropods, like spiders all three belong to class Arachnida. In most circumstances, it is not the tick bite but the toxins, secretions, or organisms in the tick's saliva transmitted through the bite that cause disease. Ticks are the leading carriers of vector-borne diseases to humans in the United States, second only to mosquitoes worldwide. They are classified in two families, Ixodidae (hard ticks) and Argasidae (soft ticks), each containing different genera and species of ticks.
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