![]() ![]() This bump may enlarge to become a spreading red ring called erythema migrans. These symptoms include fever, fatigue, headache, aching joints, nausea and a small red bump at the site of the bite. Symptoms of Lyme disease may develop within 2 to 30 days following an infective tick bite. The areas of greatest incidence in the United States are the Northeast, the Atlantic seaboard, the Great Lakes states, and northern California. Since its discovery in the early 1970s near Old Lyme, Connecticut, it has been reported widely throughout most of the country. It probably is the most frequently reported tick-borne disease in the United States. Lyme disease is caused by the spirochete Borrelia burgdorferi. Prompt removal of ticks from the skin greatly reduces the chance of transmission for Rocky Mountain spotted fever, because this pathogen is not likely to be transferred during early stages of tick attachment. In Missouri, Rocky Mountain spotted fever is transmitted primarily by American dog ticks and lone star ticks. Early diagnosis and antibiotic treatments are important. Signs may appear initially, or two days to two weeks after an encounter with an infected tick. The rash is usually accompanied by headache, backache, high fever and general malaise. Later this rash spreads to all parts of the body. Symptoms of Rocky Mountain spotted fever include a rash that often first appears on the wrists and ankles. Although a few cases of this disease do occur in the Rocky Mountains, most are reported in midwestern states such as Oklahoma, Missouri, and eastward to Virginia. ![]() ![]() Rocky Mountain spotted fever is a rickettsial disease caused by Rickettsia rickettsii. Tick bites may be irritating, but the possibility of tick-transmitted diseases causes greater concern. Males take small amounts of blood while feeding and do not become enlarged and swollen. This difference in body structure allows females to swell greatly by stretching the nonhardened portion of their bodies while they imbibe large amounts of blood during feeding. Male ticks have a hard, shieldlike plate that covers the entire top surface of their body, but in females this plate covers only about one-third of the front part of their body. The mouthparts are then inserted into the host's tissues to obtain blood. A tick uses these mouthparts to cut a small hole in the host's skin. The size and shape of the mouthparts are often used to identify different tick species. Ticks do not have a true head, only mouthparts projecting from the front edge of the body. Many other species of ticks can be found in Missouri, but they come into contact with people less frequently. The brown dog tick only feeds on dogs, but may be brought into homes with dogs and become an indoor pest. Another species, the brown dog tick, Rhipicephalus sanguineus (Figure 3), may also be common on domestic dogs. The two most frequently encountered ticks in Missouri are the lone star tick, Amblyomma americanum (Figure 1), and the American dog tick, Dermacentor variabilis (Figure 2). Female (A) Male (B), Mouthparts (C).īrown dog tick. Female (A) Male (B), Mouthparts (C).Īmerican dog tick. Ticks will also travel short distances toward a carbon dioxide source to locate potential hosts. Once on the host, ticks seek areas to settle, insert their mouthparts and begin feeding. As potential hosts pass by questing ticks, the hooks on the ends of the front legs become attached to the host and pull the tick from the vegetation. Because they are sensitive to drying out, they usually return to the base of vegetation several times a day to stay hydrated. They hold on to the vegetation with the remaining legs. Ticks locate their hosts by "questing." During questing, ticks climb to the tips of vegetation and extend their front legs out away from their bodies. Some nymphs and adults typically feed on larger animals, including humans and their companion animals. The larvae and nymphs often feed on smaller animals and birds. Immature and adult ticks are most likely to be encountered in wooded or brushy areas where their hosts are most abundant, but they can also be found in lawns if their hosts are present there. Tick larvae hatch from the eggs, are small, have only six legs, and are often called seed ticks. ![]() All stages except the egg are blood-sucking parasites. Ticks pass through four stages in their life cycle: egg, larva, nymph and adult. Ticks are close relatives of mites, spiders and scorpions. ![]()
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