Relapsing fever is an infectious disease characterized clinically by alternate periods of pyrexia (fever) and apyrexia (no fever). It is caused by bacterial species of Borrelia famliy. Relapsing fever is of two major forms, louse borne relapsing fever and tick borne relapsing fever. Maximum numbers of patients are seen because of louse borne relapsing fever.
The louse borne relapsing fever epidemic is cause by B. recurrentis, while tick borne fever is caused by variety of other borrelia species. The condition is more prevalent in Asia, Africa, South America and Saudi Arabia. It mainly occurs in developing countries. Overcrowding, poverty, prevalence of unhygienic practices and large scale displacement of population are key factors causing this disease.
Relapsing fever is curable with adequate antibiotic treatment. Detecting the disease in its early stage can reduce the mortality rate. During epidemics the mortality rate can be as high as 40 percent in untreated cases.
What Organism Causes Relapsing Fever?
As mentioned earlier, the main organism causing relapsing fever is Borrelia. The disease is spread by two vectors, louse and ticks.
The Borrelia remains in the body of louse and after 7 days the louse becomes infective. The infective fluid from the louse is spilled on the skin when the louse is crushed while scratching. The spirochetes of Borrelia can penetrate through broken skin, intact mucus membrane and sometime even the intact skin.
Tick borne relapsing fever is caused by many other species of Borrelia. The tick becomes infected by feeding on blood. After 3 to 4 days the Borrelia spirochetes are found in the saliva of ticks. The next bite infects a healthy human. Since the ovary of ticks is also infected by Borrelia, the infection is transmitted to the larva and nymphs. Ticks are thus a reservoir of Borrelia while lice are not. Children and women are severely affected as compared to men.
Symptoms Of Relapsing Fever
The incubation period is 4 to 18 days. The relapsing feature is attributed to constant change in the genetic makeup of the spirochetes. Thus all the Borrelia germs cannot get destroyed by the immune system of human being. The disease causes decrease in platelets which leads to tiny hemorrhagic rashes on skin.
Disseminated intravascular coagulation (DIC) is a dreaded complication. The liver and spleen are enlarged. Below are given important clinical features.
- Fever and constitutional symptoms: There is acute fever which lasts throughout the day or has intermittent attacks. It is accompanied with chills. The fever lasts for 3 to 6 days which is followed by period of apyrexia (no fever) of 6 to 10 days. The fever returns again after a period of relapse. In louse borne fever there is usually a single relapse while in tick borne fever there are several relapses. Headache, body ache, joint pains, red eyes, skin rashes are common during fever.
- Abdominal symptoms: Loss of appetite, nausea, vomiting, and jaundice are common. The liver and spleen are enlarged. Liver damage can lead to hemorrhagic tendencies in the form of bleeding from nose and from gastrointestinal tract.
- Cardio respiratory Symptoms: Cough and breathlessness are common. There may be changes in cardiac rhythm and rate especially in louse borne relapsing fever. During apyrexia, there is risk of low blood pressure and shock.
- Central nervous system symptoms: Confusion, stiff neck and convulsions are present in severe cases.
- There is risk of abortion in pregnant women. Repeated tick borne relapsing fever may cause visual problems.
Diagnosis And Treatment For Relapsing Fever
Laboratory findings of blood and ECG changes are useful in diagnosing relapsing fever. The spirochetes can be detected under microscope.
Relapsing fever is treated with antibiotics. In most cases the results are excellent, especially when the treatment is started at the onset of disease. The dose is recommended by the doctor according to the severity and weight of the patient.
If the condition is diagnosed and treated in the primary phase of disease, the mortality rate is less. However, the condition becomes life threatening among untreated patients. Patient who has developed CNS, heart, or liver complications has great risk.