COMMENTARY

Tickborne Rickettsial Infections Among Travelers to Africa

Jennifer McQuiston, DVM, MS

Disclosures

August 26, 2013

Editorial Collaboration

Medscape &

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Hello. I am Dr. Jennifer McQuiston with the Rickettsial Zoonoses Branch at the Centers for Disease Control and Prevention (CDC). I am here to discuss the health risks of tickborne disease and how to counsel international travelers on the importance of preventing tick bites and recognizing tickborne diseases.

Travelers who are planning safaris in sub-Saharan Africa generally receive pretravel guidance about travel vaccines, malaria prophylaxis, and food and water precautions. However, less commonly do they receive counseling on tickborne illnesses, even though African tick-bite fever, which is caused by a rickettsial infection acquired from a tick bite, is among the most common causes of febrile illness seen in travelers returning from sub-Saharan Africa. A closely related infection known as Mediterranean spotted fever may also occur in parts of Africa; this disease may be more severe but is less commonly reported.

Travelers engaging in activities that increase the likelihood of being exposed to ticks, including safaris, bushwalks, and contact with tick-infested dogs and wildlife, should be counseled on the importance of preventing tick bites.

No vaccines against African tick-bite fever or Mediterranean spotted fever are available in the United States, and antibiotics are not recommended for prophylaxis following a tick bite. The most important action for travelers is to avoid tick bites. First, travelers should dress appropriately by wearing light-colored clothing, long pants and sleeves, closed-toe shoes, and tucking in shirts and pants, to limit the amount of exposed skin. Next, travelers should use insect repellents that contain at least 20% DEET on the skin, because lower concentrations of DEET labeled to repel mosquitos may not work against ticks. Most "natural" products, such as citronella, are not proven as effective against ticks. Although permethrin should not be used on skin, it is highly effective when used to treat clothing and shoes and will repel ticks when the traveler walks in the bush or high grass. Commercially treated clothing and do-it-yourself treatments are widely available.

It can take several hours for a tick to attach and begin transmitting disease, so the sooner the tick can be found and removed, the better. Counsel travelers to check their bodies for ticks frequently when outside, to increase the likelihood of finding a tick before it can transmit disease. Travelers should bathe or shower as soon as possible after engaging in outdoor activities, then do a full-body tick check, including the scalp, with a handheld or full-length mirror. Remove ticks by using fine-tipped forceps or gloved or shielded hands if forceps are not available. Grasp the tick as close to the skin as possible and pull upward with steady, even pressure. After removing the tick, travelers should thoroughly clean the bite area and their hands with rubbing alcohol, an iodine scrub, or soap and water.

Finally, travelers should be on the lookout for any of the following symptoms: fever, chills, headache, fatigue, myalgia, and rash, even after they return home and even if they do not recall being bitten by ticks. A blackened area called an eschar may be seen at the site of the tick bite but is not always present.

Although African tick-bite fever is rarely fatal, Mediterranean spotted fever can cause a more severe illness. The 2 infections have similar clinical presentations and can be approached using the same treatment and diagnostic plan. Travelers who develop these symptoms during or within 2 weeks after travel will recover faster with treatment and should be encouraged to seek medical care and to inform their providers about their recent travel. Physicians should consider tickborne rickettsioses as a possible cause of fever in returning travelers, keeping in mind that other causes of illness are also possible. You should test for tickborne rickettsioses by using commercial tests for Rocky Mountain spotted fever, or through specialized tests available at the CDC or reference laboratories. However, because early lab tests for tickborne rickettsioses are not sensitive enough to guide treatment decisions, all suspected cases should be treated on the basis of clinical suspicion. Doxycycline is the treatment of choice in patients of all ages, using a standard dose and continuing for 5-7 days. More information can be found at www.cdc.gov/ticks.

If you see patients who are planning a safari or outdoor vacation, particularly in sub-Saharan Africa, remember to urge them to follow these guidelines to avoid tickborne illnesses. Keeping tickborne disease on the radar for both you and travelers will help ensure safe and healthy travel.

Web Resources From CDC

Ticks

Avoiding Ticks

Tick Removal

Symptoms of Tickborne Illness

Travelers' Health

Captain Jennifer McQuiston, DVM, MS, serves as the Epidemiology Activity Leader in the Rickettsial Zoonoses Branch in the Division of Vectorborne Diseases (DVBD) at the National Center for Emerging and Zoonotic Infectious Diseases in the US Centers for Disease Control and Prevention (CDC). She is located in Atlanta, Georgia, at the CDC main headquarters.

Dr. McQuiston joined CDC in 1998 as an Epidemic Intelligence Service (EIS) Officer, conducting research and the investigation of outbreaks related to zoonotic diseases (diseases that are transmitted from animals to people). She has worked extensively on rickettsial diseases such as Rocky Mountain spotted fever, ehrlichiosis, anaplasmosis, Q fever, typhus, and cat scratch disease. From 2005 to 2007, she also served as Zoonoses Team Leader in CDC's Division of Global Migration and Quarantine, managing issues related to animal importation and the infectious disease risks they pose.

Jennifer McQuiston attended Virginia-Maryland Regional College of Veterinary Medicine, where she received a DVM in 1997 and a master's degree in molecular biology in 1998. She is a diplomate of the American College of Veterinary Preventive Medicine and has been the recipient of national awards, including the Daniel E. Salmon award from the National Association of Federal Veterinarians, and the James H. Steele Award from CDC, for outstanding work on veterinary public health issues.

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