What is tick bite fever?
Tick bite fever is caused by a bacterial infection transmitted by ticks. This condition occurs in many areas of the world and is often known by a variety of names
What causes tick bite fever?
The organism that causes tick bite fever belongs to the Rickettsial family of bacteria. There are a number of different species of Rickettsia. These organisms are relatively small and are only able to survive inside cells. They are found in certain wild and domestic animals, and ticks acquire the organisms when they feed on these animals. When the tick bites a human, the bacterium is transmitted in the saliva. In South Africa, the cause of tick bite fever is either R. conorii or R. africae.
How do you catch tick bite fever?
As mentioned above, the organisms are transmitted in the saliva of an infected tick when it bites humans. Alternatively, if the tick is crushed on your skin, the Rickettsia may be able to enter through a small abrasion. Being bitten by ticks usually occurs in rural or wilderness areas i.e. when you are out camping, hiking in long grass etc. The ticks that are able to harbour the organism belong to the Amblyomma, Dermacentor or the Rhipicephalus family of ticks.
Symptoms and signs of tick bite fever
The incubation period (the period between being infected and displaying symptoms) is about five to seven days. Symptoms can vary, depending partly on the organism involved and the age and underlying health status of the patient.
The typical triad of symptoms includes fever, severe headache and a rash. There is often an eschar at the site of the tick bite. This is a black mark that looks like a small ulcer (2-5mm in diameter) with a black centre or scab. It may look something like a spider bite. The eschars can be single or multiple and can sometimes be very difficult to find. The eschar usually appears once the fever appears, as does the headache and malaise (general feeling of ill-health). Lymph nodes near the eschar may be enlarged.
A rash is usually, but not always, present. It generally consists of small red marks (macules) on the skin, sometimes raised slightly above the surface. It typically starts on the limbs and spreads to the trunk, and can involve the entire body, including the palms of the hands and soles of the feet.
What is the outcome of tick bite fever?
African tick bite fever is usually mild, and death and serious complications are very uncommon. Complications can include encephalitis, pneumonia and damage to the brain and heart.
How is tick bite fever diagnosed?
The diagnosis is suggested by a history of typical symptoms in someone with possible recent exposure to ticks. i.e. someone who had been hiking or camping in a rural or wilderness area. The presence of the rash and an eschar is a very strong diagnostic sign for tick bite fever. Some other conditions that may be confused with tick bite fever are meningitis, malaria, measles and German measles.
Because the organism lives inside cells, it is very difficult to culture it in a laboratory, and this isn’t routinely offered as a diagnostic test. Antibodies to the bacteria can be detected in the blood, and these can be looked for in the laboratory. However the tests may only become positive after a couple of weeks, so while they may help to confirm a diagnosis, they are not always immediately helpful early on in the infection. If you have typical symptoms of the infection, and a history of possible exposure to ticks, your doctor may decide to treat you before results of the serological tests are known.
How is tick bite fever treated?
Some forms of tick bite fever are fairly mild and self-limiting – people may get better on their own without specific treatment. This can take up to two weeks however, and treatment with an antibiotic can shorten the duration of symptoms and reduce the chance of a serious side effect. In severe cases, antibiotic therapy is more important, and can be life saving. The antibiotic doxycycline is the preferred agent for treating tick bite fever. Alternatives include chloramphenicol, and ciprofloxacin.
Can tick bite fever be prevented?
The easiest may to prevent tick bite fever is to avoid being bitten by ticks. Avoiding rural or wilderness areas where ticks are likely to occur is one way to achieve this, but not a great
solution if you enjoy hiking and camping. Other measures are generally common sense, such as wearing insect repellents and long trousers and sleeves. There is no vaccine against tick bite fever, and taking prophylactic antibiotics (as one does for malaria) has never been shown to be effective or necessary.
yes, that’s what WE BOTH had. we have definitely been africanly baptised… BY A TICK!