Sleeping Sickness

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INTRODUCTION

  • Sleeping sickness (trypanosomiasis) is a protozoan infection transmitted to humans by the tsetse fly bite.
  • If left untreated, it can lead to death within months or years.
    Protozoa are single-celled organisms that are thought to be the most basic animal life form.
  • The protozoa that cause sleeping sickness are a flagellated variety (flagella are hairlike projections from the cell that aid in mobility) that can only be found in Africa.
  • The Trypanosoma brucei complex is the name given to the protozoa that cause sleeping sickness in humans.
  • It is further classified as a Rhodesian (Central and East Africa) and a Gambian (Central and West Africa) subspecies.
  • The Rhodesian variety lives within antelopes in savanna and woodland areas, causing no harm to the antelope’s health. (While the protozoa do not cause illness in antelopes, they are lethal to cattle that become infected.)
  • Tsetse flies pick up the protozoa after biting and sucking the blood of an infected antelope or cow.
  • The protozoa cycle through several different life forms within the tsetse fly, eventually migrating to the tsetse fly’s salivary glands.
  • Once the protozoa have been harbored in the salivary glands, they can be deposited in the bloodstream of the fly’s next victim.
  • Once the protozoa are in the salivary glands, they will be deposited in the bloodstream of the fly’s next blood meal.
  • Game wardens and visitors to East African game parks are the most likely to become infected with Rhodesian trypanosomes.
  • The Rhodesian strain of sleeping sickness is far more severe, with a much higher chance of death.
  • The Gambian strain of Trypanosoma thrives in tropical rain forests across Central and West Africa, does not infect game or cattle, and is primarily a threat to people who live in such areas. Visitors are rarely infected.

 

SYMPTOMS

  • A sore appearing at the tsetse fly bite site two to three days after being bitten may be the first sign of sleeping sickness.
  • There is redness, pain, and swelling. Stage I disease develops two to three weeks later as a result of the protozoa being carried through the blood and lymphatic circulations.
  • This systemic (symptoms affect the entire body) phase of the illness is characterized by a high fever that drops to normal and then spikes again.
  • A rash with intense itching is possible, as are headaches and mental confusion.
  • Extreme swelling of lymph tissue, enlargement of the spleen and liver, and swollen lymph nodes are all symptoms of the Gambian form.
  • Winterbottom’s sign is typical of Gambian sleeping sickness; it is characterized by a visibly swollen area of lymph nodes behind the ear and just above the base of the neck.
  • The heart may be affected by a severe inflammatory response during this stage, especially if the infection is caused by the Rhodesian form.
  • Many of the symptoms of sleeping sickness are the result of the patient’s immune system’s attempts to rid itself of the invading organism.
  • Immune cells that are overly active damage the patient’s organs, resulting in anaemia and leaky blood vessels. These dilated blood vessels aid in the spread of protozoa throughout the patient’s body.
  • One reason for the immune system’s strong reaction to Trypanosomes is also why the Trypanosomes survive so well.
  • The protozoa have the ability to rapidly change specific markers on their outer coats.
  • These types of markers typically stimulate the host’s immune system to produce immune cells that are specifically designed to target the markers and allow for the rapid destruction of invading cells.
  • Trypanosomes can express new markers at such a rapid rate that the host’s immune system cannot keep up.
  • The nervous system is involved in Stage II sleeping sickness.
  • The Gambian strain has a distinct phase in which the predominant symptomatology is brain-related. Speech becomes slurred, mental processes slow, and the patient sits and stares or sleeps for extended periods of time.
  • Other symptoms are similar to Parkinson’s disease, such as walking imbalance, a slow and shuffling gait, trembling limbs, involuntary movement, muscle tightness, and increasing mental confusion.
  • These symptoms progress to coma and then death.
Sleeping Sickness
The trypanosome that causes sleeping sickness is commonly transferred to humans by mosquitoes.

 

 

DIAGNOSIS

  • A microscopic examination of fluid from the site of the tsetse fly bite or swollen lymph nodes can be used to diagnose sleeping sickness.
  • Culturing blood, bone marrow, or spinal fluid is one method for diagnosing Rhodesian trypanosome.
  • These cultures are injected into rats in order to promote the development of blood-borne protozoan infection. Within one to two weeks, this infection can be detected in blood smears.

 

MEDICATIONS

  • Medications that are effective against the Trypanosoma brucei complex protozoa have a high risk of side effects. Suramin, eflornithine, pentamidine, and several drugs containing arsenic (a potentially toxic chemical) are effective anti-trypanosomal agents.
  • Each of these medications must be carefully monitored to ensure that they do not cause serious complications such as a fatal hypersensitivity reaction, kidney or liver damage, or brain inflammation.
  • Trials are currently underway to assess the efficacy of new medications for the treatment of trypanosomiasis.

PREVENTION

  • Avoiding contact with the tsetse fly is essential for preventing sleeping sickness; insect repellents, mosquito netting, and clothing that covers the limbs to the wrists and ankles are essential.
  • There are no immunizations available to prevent sleeping sickness at the moment.