Diagnosis, Treatment and Control of Sleeping Sickness

• Surveilance
  Mobile team visiting an African village
  Mobile teams used to visit on a routine basis the rural areas of tropical Africa to screen the population for the presence of trypanosomiasis and other diseases. With the deteriorating situation in Central Africa, this routine screening of the population has come to an almost complete halt.
• Diagnosis
  One of the easiest tests for trypanosomiasis is to check for the swelling of the lymphe nodes in the neck. This is the first sign, in addition to the typical chancre at the place of the bite of the tsetse fly, of the presence of trypanosomes in the body. Other tests that have to be carried out are the analysis of a thick smear of blood forthe presence of alive trypanosomes, or that of a giemsa-staine blood smear . The latter may be laborious since parasitaemia may be very low and trypanosomes may not be detectable. Other less laborious tests are the CATT (card agglutination) test for the presence of circulating antibodies. Any positive test should be confirmed by the detection of trypanosomes in the blood. For this purpose larger quantities of blood (a few ml) may be applied to a small DEAE cellulose column to separate trypanosomes from blood components. After centrigfugation trypanosomes can be detected in the pellet microscopically.
  
  Once an infection has been confirmed by the presence of trypanosomes in the circulation, it has to be established whether the patient is still in the early or already in the late phase of the disease. In other words whether there are trypanosomes already in the central nervous system. This information will be decisive for the further treatment of the patient. The presence of trypanosomes in the central nervous system can only be diagnosed by analyzing fluid from the spine after a lumbar punction. Presence of either trypanosomes, or an increased white blood cell count, or elevated IgM, are all indications for central nervous system involvement.

Treatment
When the patient is in the late stage, treatment with organic arsenicals such as Arsobal (or Mel B) is compulsary. For West African cases of sleeping sickness that are refractory to arsenicals a treatment with Eflornithine (if available) is recommended. If trypanosomes can only be detected in the circulation, treatment with either Suramin in East-Africa or with Pentamidine in West Africa is recommended. For more details on the various drugs in use for sleeping sickness click here.

• Tsetse control

   

  • Insecticides
    It will be impossible to eradicate tsetse from the African continent. Thus control measures must exist in mainaining the lowest possible level of exposure of the population to the infective bite of a tsetse fly. Control measures consist in low-cost ground spraying techniques from fixed wing aeroplanes with residual insecticides such as endosulfan of riverine areas. However, such measures have little selectivity and are normally not designed for sleeping sickness alone.

     

  • Tsetse traps
    Another more selective measure is the use of specific tsetse traps. The advantage of the use of tsetse traps is that they are cheap, cost-effective and community based. Several types of trap have been developed, but a cheap and very effective one is the biconical trap made of blue tissue. Its blue colour attracts the flies which then enter the trap via holes in the lower part of the bicone. Once inside, the flies try to escape upwards towards the sun light and are trapped and killed in a trapping device attached to the apex of the upper cone that often contains some diesel oil. The effectiveness of the traps can be improved even more by impregnating them with insecticides and by the use of olfactory attractants, such as acetone, carbon dioxide gass and urine of oxen. A reduction of the tsetse burden by 90 - 95 % can so easily be obtained in and around villages.These traps have actually resulted in total elimination of the flies from a large area of a wildlife park in Zimbabwe. The drawbacks include the cost of maintaining the traps, for on ce the bait expires the flies will soon re-enter the area.

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