Rickettsial and other tick-borne infections.

Tick bites are best prevented by people avoiding tick-infested areas. When this is not possible, tick bites may be prevented by the wearing of long trousers that are tucked into boots. The best method to avoid tick bites is twofold: application of a topical deet (N,N-diethyl-m-toluamide) repellent to exposed skin, and treatment of clothing with permethrin. This system is currently used by the US Army to protect soldiers. Ticks can crawl underneath clothing and bite untreated portions of the body; therefore, treating clothing is imperative. Permethrin is nontoxic to humans, and can be used in any age group. Permethrin is commercially available. Checking clothing regularly while in tick-infested areas is highly recommended to back up the few hours of protection provided by the insect repellents. It is also recommended that the entire body be carefully screened for ticks and other parasites by campers and hunters while they are staying in and after leaving infested areas. Any tick found should be removed immediately. Removing ticks may not be easy. It is best to use blunt, rounded forceps, and a magnifying glass to remove ticks, especially when immature ticks are found. The forceps are used to grasp the mouthparts of the tick as close as possible to the skin, and then the tick is pulled upward, perpendicular to the skin, with a continuous and steady action. Usually any mouth parts of the tick retained in the skin are eliminated uneventfully by the body. Other methods of removing ticks, such as using fingers, lighted cigarettes, petroleum jelly, or suntan oil, should be avoided. Killing the tick in situ may increase the risk of regurgitation by the tick and the transmission of infectious agents. Most stick bites are uncomplicated, and result only in benign cutaneous inflammatory reactions that may be pruritic for a few days. As a result of mouthparts being retained at the feeding site, a granuloma may rarely develop. There are no data to indicate that antimicrobial prophylaxsis is beneficial to the tick-bitten patient to prevent disease. It must be kept in mind that the risk of transmission of disease increases with the duration of attachment and generally requires greater than 24 to 48 hours. The degree of tick engorgement or the time since tick exposure and discovery of the tick may be used to establish the likely duration of attachment and the risk of disease transmission. Reducing and controlling tick populations is difficult. Habitat modifications, including vegetation management by cutting, burning, and herbicide treatment, and drainage of wet areas are one strategy for tick control, but their effects are often short-lived, and they can cause severe ecologic damage. Chemicals used to control ticks may cause environmental contamination, and therefore, toxicity for humans and animals. Biologic control methods for ticks include the promotion of natural predators. Natural predators of ticks are beetles, spiders, and ants, and parasites such as insects, mites and nematodes. Tick control is best based on the concept of integrated pest management, in which different control methods are adapted to one area or against one tick species with due consideration to their environmental effects. Tick-borne diseases are increasing in prevalence. Perhaps it is because people are undertaking more outdoor activities, which result in contact with ticks and their pathogens. Clinicians should be aware of the clinical sign of tick-transmitted diseases, because morbidity and mortality as a result of these diseases increases substantially if there are delays in diagnosis and treatment. Tick-borne illness occur in distinctive geographic areas. The reporting of these illnesses and diseases to the health department enables the gathering of information and statistics. The public should be informed about the risks of disease in tick-infested areas and the means of preventing infections. The most common diseases are caused by Rickettsia, Borrelia, and Ehrichia, but with continued study, new pathogens and diseases will continue to emerge.