Sleeping sickness is also known as trypanosomiasis or African sleeping sickness.
It is caused by two protozoan parasites that are morphologically similar but cause dramatically different diseases.
Parasites That Cause Sleeping Sickness
These dangerous parasites are carried by the tsetse fly. East African sleeping sickness is caused by the parasite Trypanosoma brucei rhodesiense, whereas West African sleeping sickness, also known as Gambian sleeping sickness, is caused by Trypanosoma brucei gambiense.
East African sleeping sickness is a severe disease that typically leads to death within weeks or months if not treated. The initial bite leaves a distinctive sore spot called a chancre.
Symptoms, which appear one to four weeks after infection, may include swollen lymph nodes, irritability, fever, severe headache, fatigue, muscle and joint pain, and a skin rash.
During the second stage of the disease, the parasite crosses the blood-brain barrier and attacks the central nervous system. Neurological complications include slurred speech, confusion, and difficulty with walking.
Like East African sleeping sickness, West African (Gambian) sleeping sickness is a severe disease that is deadly if not treated. However, it is a chronic disease in which symptoms may not appear for months to years after the initial infection.
Initial symptoms include swollen lymph nodes, swelling of face and hands, skin rash, fever, severe headaches, muscle and joint pain, and weakness. Weight loss is common as the disease progresses.
Neurological impairment occurs during the second stage in which the sufferer can experience personality changes, slurred speech, changes in sleep patterns, progressive confusion, difficulty with walking, and seizures.
Sleeping Sickness Causes
Two organisms, T. brucei rhodesiense and T. brucei gambiense cause sleeping sickness. The more severe form of the illness is caused by rhodesiense.
T. brucei gambiense is the cause of a persistent infection that lasts several years until it finally develops into a coma, from which the patient cannot be woken. Hence the name 'sleeping sickness'.
If the central nervous system is severely affected, the patient can no longer be cured, and eventually dies, possibly from other infections that may be superimposed on the primary disease.
Long trousers, long-sleeved jackets and socks thick enough to stop the insects biting will protect you, but it may be hard to follow such advice in a hot climate.
Sleeping Sickness Symptoms
Symptoms of sleeping sickness start with fever, headaches, and joint pains. If untreated, the disease slowly overcomes the defences of the infected person, and symptoms spread to anemia, endocrine problems, and cardiovascular and kidney disorders.
The disease next enters a neurological phase when the parasite passes through the blood-brain barrier. The symptoms of the second phase are what give the disease its name: besides confusion and reduced coordination, the sleep cycle is disturbed with bouts of lethargy punctuated with weird periods progressing to daytime somnolence and nighttime insomnia.
Without treatment, the disease is fatal, with progressive mental deterioration leading to coma and death. Damage caused in the neurological phase can be irreversible.
Spreading Of Sleeping Sickness
The tsetse fly is the host for the parasite, which is transmitted by biting. The bite is severely painful for it to be noticed, but only a few of the flies carry the infection. When the fly bites, the parasite is able to enter the bloodstream via the bite, from where it passes over into the lymph and the central nervous system.
The flagellate reproduces in the blood, and a fly that bites an infected human may therefore itself become infected, and over the course of four to six weeks this fly may infect further humans.
Sleeping Sickness Diagnosis
To start the diagnosis, the parasite has to be detected in a blood sample, fluid from lymph nodes or cerebrospinal fluid. Diagnosis of sleeping sickness can be done by microscopic examination of fluid from the original sore at the site of the tsetse fly bite.
Trypanosomes will be present in the fluid for a short period of time following the bite. If the sore has already resolved, fluid can be obtained from swollen lymph nodes for examination.
Sleeping Sickness Treatment
If the disease is diagnosed early, the probability of cure is high. Without treatment, sleeping sickness will lead to death. Unfortunately, however, those medications effective against the Trypanosoma brucei complex protozoa all have major potential side effects for the patient.
Suramin, eflornithine, pentamidine, and several drugs, which contain arsenic (a chemical which in higher doses is highly poisonous to humans), are all efficient anti-trypanosomal agents.
Each of these drugs, however, requires careful monitoring to ensure that the drugs themselves do not cause serious complications such as fatal hypersensitivity (allergic) reaction, kidney or liver damage, or inflammation of the brain.