Tick Bites

A tick bite is the resulting injury from a tick sting, which could produce a local inflammatory reaction, a systemic toxemia, or after an incubation period, a tick-borne disease such as those caused by virus, rickettsias, bacteria, and protozoans. Ticks are hematophagic arthropods and bite humans and/or animals to obtain blood.

From an epidemiological point of view, it is important to mention that in some countries (particularly in northern and developed countries) more vector-borne diseases are transmitted by ticks than by any other agent. During the past 30 years, tick-borne diseases have taken on increased importance as humans (in many cases with their pets) have moved into rural areas and increased their recreational outdoor activity, thus being more frequently exposed to tick bites.

Taxonomically, medically important ticks belong to the class Arachnida, order Acarina and suborder Ixodes with two families: Argasidae (with the genuses Argas, Otobius, and Ornithodoros) and Ixodidae (with the genuses Amblyomma, Dermacentor, Boophilus, Ixodes, Rhipicephalus, and Haemophysalis). Most important ticks belong to the last family, being responsible of transmission of diseases such as Rocky Mountain spotted fever, Q fever, bouton-neuse fever, ehrlichiosis, tularemia, Colorado tick fever, Queensland tick typhus, Siberian tick typhus, tularemia, Central European tick-borne encephalitis, Congo-Crimean fever, tick-borne relapsing fever, babesiosis, and Lyme disease, among others.

As blood feeders, ticks can be a nuisance; their bites can cause irritation and, in the case of some ticks, paralysis. The prevention of tick bites and the prompt detection and removal of attached ticks can reduce the chances of infection. To limit the chance of getting a tick bite, it is recommended to avoid tick-infested areas when possible and avoid shortcuts through heavily wooded, tick-infested areas. Use caution when entering tick-infected areas by staying in the center of paths, avoiding sitting on the ground, and conducting frequent tick checks. Additionally, it is also advisable to dress properly by wearing light-colored clothing.

It is important for physicians to consider the illnesses associated with tick bites when patients present with influenza-like symptoms.

The use of repellents is also important in preventing tick bites. The primary active ingredient in most repellents today is DEET (N,N-diethyl-3-methylben-zamide or N,N-diethyl-m-toluamide), which repels ticks and decreases the chance of bites (depending upon the concentration). Other repellent commonly used to prevent bites is permethrin (used frequently for the application on clothing or nets).

It is important for physicians to consider the illnesses associated with tick bites when patients present with influenza-like symptoms. A petechial rash initially affecting the palms and soles of the feet is associated with Rocky Mountain spotted fever, whereas erythema migrans is associated with Lyme disease. [Page 1669]Moreover, ticks can cause important dermatologic disease directly by their bite, which also require specialized medical attention.