Ticks transmit disease by the transfer of micro-organisms such as rickettsia, viruses, protozoa, spirochetes, pyroplasma and so on into the bloodstream of the host. There are a number of active research studies to determine if there are more diseases attributable to tick bites.
Lyme disease - Borrelia The most common of the tick born diseases, caused by bacteria-like spirochete which received its name when the disease was first discovered in 1975 in Lyme, Connecticut. One of the symptoms is a ring shaped reddish rash can be seen around the bite typically over 2 inches in diameter which will turn gradually pale as it expands from the center. Because untreated Lyme disease can be responsible for facial palsy, meningitis, nerve inflammation, brain swelling, intermittent arthiritis and irregularities in heart rhythm, it has been called the "great masquerader." It can be cured with antibiotics if treated immediately.
Rocky Mountain Spotted Fever First identified in the Rocky Mountain area, it is caused by the rickettsia bacteria. Early RMSF is characterized by high fever, severe headache, myalgias, and gastrointestinal symptoms. In late illness, there may be photophobia, confusion, ataxia, seizures, cough, dyspnea, arrhythmias, jaundice, severe abdominal pain, thrombocytopenia, and hyponatremia. The rash may be asymmetric, localized, or absent. It usually begins 2 to 5 days after onset of fever as 1- to 5-mm macules, typically on ankles, wrists, and forearms; the palms and soles can also be involved. The rash spreads centripetally to the trunk. A petechial rash occurs on or after day 6. It is treated with antibiotics.
Ehrlichia The group of bacteria known as Ehrlichia has been known to veterinary medicine since 1935, but in 1953, it was discovered in humans. Signs and symptoms include fever, headache, myalgias, nausea, vomiting, cytopenias, and elevated transaminase levels. Illness can be very severe, especially in the immunocompromised. Patients with severe disease may develop meningitis, adult respiratory distress syndrome, disseminated intravascular coagulation (DIC), and renal failure. Two percent to 3% of patients die from the disease, although in immunocompromised patients, the mortality may be as high as 30%. Reinfection has been noted; thus, initial infection may not confer life-long immunity.
TBE Tick-borne meningoencephalitis or Tick-borne encephalitis is a tick-borne viral infection of the central nervous system affecting humans as well as most other mammals. The virus can infect the brain (encephalitis), the membrane that surrounds the brain and spinal cord (meningitis) or both (meningoencephalitis). It is transmitted by the bite of infected deer ticks or (rarely) through the non-pasteurized milk of infected cows. Russia and Europe report between 10-12,000 human cases annually. The disease is incurable once manifest, but the virus can be deactivated and prevented by vaccination. In humans, the disease is lethal in approximately 1.2% of cases and leaves 15-20% of its survivors with permanent neurological damage.
Babesia Babesia is a tick-transmitted protozoal parasite that can cause malaria-like symptoms and hemolytic anemia. Asplenic, elderly, and immunocompromised patients are at greatest risk for severe disease; however babesiosis can be serious in immunologically normal persons. Babesiosis is emerging as a disease of public health significance in the U.S.A, with increased reports of clinical, even fatal, cases in areas where the risk of infection with Babesia was not recognized previously. Until recently, human babesial infections in this country have been attributed to Babesia microti, derived from rodents. There is increasing evidence to suggest that human babesiosis in the U.S.A may be caused by babesial parasites that are antigenically and genotypically distinct from Babesia microti.
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