Reviewed By: Pramod Kerkar, MD, FFARCSI

What is African Tick Bite Fever?

African tick bite fever is a bacterial infection spreading through the bite of infected ticks. Usually the symptoms in African tick bite fever appears within 2 weeks after a tick bite and most often include fever, muscle soreness, headache, rashes etc. In case of African tick bite fever, the site of the tick bite turns black with an area of redness around it. One can notice more than one bite site, however sometimes the site of bite may not be visible. The infection of African tick bite fever is usually not severe and there have been no recorded deaths from it.

African tick bite fever also known as ATBF is causes by the bacterium Rickettsia africae in Sub Saharan Africa and the West Indies. This bacterium is transmitted to humans by ticks in the Amblyomma genus. This is actually a type of spotted fever and symptoms may not always be present. Severe complications in African tick bite fever are very rare. Headache, rash, fever etc are some of the symptoms and diagnosis is based on the symptoms. You physician may advice you for antibiotics so as to treat the condition.

What is African Tick Bite Fever?

Who is at Risk of Getting African Tick Bite Fever?

Travelers to Sub-Saharan Africa and the West Indies are mostly at risk of getting the infected with African tick bite fever. You may be more at risk for African tick bite fever if your travel plans include outdoor activities like hiking, camping, game hunting in wooded or grassy areas. Ticks that are infected with tick bite fever are mostly active during the month of November through April. So, you may be at a risk of getting African tick bite fever if you are visiting the places during these months.

Epidemiology for African Tick Bite Fever:

Cases of African tick bite fever have been frequently reported in the literature among the international travelers more than the local populations. Among locals living in endemic areas, exposure at a young age and mild symptoms or lack of symptoms, and also decreased access to diagnostic tools, may lead to reduced diagnosis. In Zimbabwe, where Rickettsiae africae is endemic, a study has reported an estimated yearly incidence of 60 to 80 cases per 10, 000 patients.

As per published data over 35 years, near to 200 confirmed cases of African tick bite fever in International travelers have been reported. About 80% of these cases occurred in travelers returning from South Africa.

Causes of African Tick Bite Fever:

Bacteriology:

The bacterium causing the African tick bite fever is the Rickettsia africae; which is a gram negative, obligate intracellular, bacterium belonging to Rickettsia genus.

Vectors:

In Sub Saharan Africa, the most common vectors of Rickettsia africae are two species of hard ticks namely; Amblyomma variegatum and Amblyomma hebraeum. Other species of Amblyomma in Sub-Saharan Africa may also transmit Rickettsia africae. Amblyomma ticks, unlike other hard tick species, actively seek out hosts. These ticks are known to be more aggressive and it is also known that several ticks may attack at once, causing clusters of African tick bite fever cases within groups of people travelling or working together.

Pathogenesis:

After R.africae infects humans via a tick bite, it invades endothelial cells in the person's circulatory system or in veins, arteries and capillaries. Then after the body releases chemicals that cause inflammation and thus resulting in characteristic symptoms such as fever, headache etc. Rickettsia bacteria species such as R. africae replicate around the area of the initial tick bite and cause cell death or necrosis and inflammation of lymph node. This leads to the characteristic eschar.

Symptoms of African Tick Bite Fever:

Symptoms of the African tick bite fever generally appear 2 weeks after the bite has occurred. Symptoms of African tick bite fever are usually seen in parts of Zimbabwe, Kenya, Tanzania, Botswana and parts of Caribbean. Following are some of the symptoms noted.

  • Influenza like symptoms such as fever, chills, body ache, fatigue, headaches, dizziness etc.
  • Occurrence of Inoculation eschar or a skin lesion at the site of the tick bite. There may also be multiple lesions which may be present. These lesions are red, painful, or inflamed.
  • There may also be swelling in the glands
  • Though sometimes, rash may occur; usually South African tick bite fever usually does not cause a rash, like in other tick bite cases.

Complications Associated With African Tick Bite Fever:

Usually complications in case of African tick bite fever are rare and hardly life threatening. Some of the complications may include:

  • Prolonged fever, where fever may last for more than 3 weeks
  • Moderate to severe headache
  • Reactive arthritis

Diagnosis for African Tick Bite Fever:

  • Diagnosis is mostly delayed since the antibodies are mostly released only after a few weeks from when the tick bite has first occurred.
  • Diagnosis for African tick bite fever is done via a biopsy, or in most of the cases it is done by a simple blood test. This reveals if there is an infectious pathogen present.
  • Immunohistochemical staining is also done for determining if rickettsial organisms are present.

Treatment for African Tick Bite Fever:

African tick bite fever is treated with antibiotics. One needs to take 2 week antibiotic course of oral Doxycycline Hydrochloride 100 mg two times a day which is usually prescribed. Usually patients feel better after taking this course of antibiotic, though in certain cases the fever may stay longer and symptoms like joint pain, fatigue etc would also be there. In some cases residual scar at the inoculation site may also be seen for a while. Taking the complete course of medication is essential for you or else the infection might recur.

Precautions to Be Maintained By Travelers to Keep Away From African Tick Bite Fever:

Precautions to Maintain While Traveling:

There are specific ways how travelers to Africa or West Indies can keep away from African tick bite fever. Below are certain precautionary measures.

  • By wearing full sleeves shirts and full pants
  • By covering or tying loose ends of pants or tucking its ends inside the socks.
  • While hiking along grassy trails or wooded areas, shoes must be worn. Make sure you always walk in the center of the trail while avoid grass as much as possible.
  • By spraying the entire body and clothing with 20% DEET spray which is an insecticide known to deter most bugs. However, make sure the product does not get in to your eyes.
  • Travelers can protect themselves from African tick bite fever by using permethrin treated clothing or gear. Most treated fabrics remain effective for at least 100 washes. Avoid spraying permethrin based sprays directly on your body.

Precautions to Follow After Getting Back From the Trail:

  • Examine all the members of the hiking group closely for ticks
  • In case a tick is found attached to anyone, use the following steps for removing it completely.
  1. Use tweezers for grasping the tick near its head close to the skin. Make sure you are not squeezing the tick or its blood could go back in to the bite site and cause infections. Firmly and gently pull the tick out ensuring no mouth parts are left behind. Then dispose off the tick.
  2. Wash your hands and also the bitten area by using an antibacterial soap
  3. Make sure that your clothing and hiking or camping gear is free from ticks. Wash all the items in hot water after you return home.
  • In case you feel sick and believe you experience fever-like symptoms, make sure you consult the doctor immediately. Also be sure to inform him or her about the travel.

Conclusion:

It is very true that contracting African tick bite fever is not fun, especially after a nice safari in the jungles. Hope this information is pretty beneficial for you. Kindly do not delay meeting with your doctor in case you have any of the symptoms that look like African tick bite fever so that you are well treated and in a proper time.

References

Also Read:

Pramod Kerkar

Written, Edited or Reviewed By:

, MD,FFARCSI

Pain Assist Inc.

Last Modified On: June 5, 2018

This article does not provide medical advice. See disclaimer

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