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African Trypanosomiasis aka African Sleeping Sickness

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´╗┐African Trypanosomiasis aka African Sleeping Sickness Problem: Human African Trypanosomiasis (HAT) is an infectious parasitic disease transmitted by vectors. The main problem biologists are trying to solve for this disease is to find a cure or at the very least, prevent it by controlling the spread of it. The parasites that cause this disease are Trypanosoma brucei rhodensiense in Southern/Eastern Africa and Trypanosoma brucei gambiense in Northern/Western Africa. Tsetse fly (Glossina genus) bites are the primary biological vectors for this. The bites can only transport the disease if they have already acquired the infection from animals or human beings affected by the protozoa. Tsetse flies are only found in Sub-Saharan Africa but only particular species transmit the disease. Moreover, in many regions the flies are found but sleeping sickness is not. People living in rural populations where transmission does occur are most exposed to the disease. This is usually because they depend on agriculture, fishing or hunting and are more unprotected to the tsetse fly. The sleeping sickness develops when a tsetse fly bites an infected person. ?Flies can remain infected for life (2-3 months). Tsetse flies inject over 40,000 metacyclic trypanosomes when they take a blood meal. The minimum infective dose for most hosts is 300-500 organisms, although experimental animals have been infected with a single organism.? [2] [see figure 1 for more detail] Inside the fly the parasites then divide to reproduce, maturing in the fly?s gut. ...read more.


This clearly proves that Elfornithine is the best drug used to treat late-stage T.b.r. Moreover, the incidences of relapse show that the effectiveness of the Melarsoprol treatment has reduced. Elfornithine is less likely to cause deaths too. This is clearly proven by the risk factor ratio for death. ?when compared with Elfornithine, standard Melarsoprol was found to be a risk factor for both death (odds ratio (OR) = 2.87; 95% confidence interval (CI) = 1.03-8.00) and relapse (hazard ratio (HR) = 2.47; 95% CI = 1.22-5.03)?. [10] [see figures 4 and 5] Implications: An economic problem in manufacturing Melarsoprol is that it is uncertain if it will be continued in production for commercial reasons. Moreover, rises in prices of medication will result in less medication being provided at the same budget. It is well known that Africa is very far behind in the developing world and it will become increasingly harder to pay for medicine for such a large population. ?There are also problems associated with manufacturing the raw material required for Melarsoprol (containing arsenic) which is highly contested for ecological reasons.? [5] Manufacturing arsenic whilst endeavouring to maintain good environmental health can be difficult. An unfortunate implication of this drug that it can cause reactive encephalopathy (encephalopathic syndrome) and this can be fatal to a percentage of people taking this drug. That percentage ranges from 3% up to 10%. In addition to this, the medicine is derived from arsenic and can cause arsenic poisoning which is also fatal. ...read more.


This ?good bacteria? is found in the gut, muscle and salivary glands of the tsetse fly. Researchers in Belgium have found a way to use these bacteria to harm the protozoa by releasing antibody fragments against the trypanosome. "When we looked at living trypanosomes under conditions that mimic the inside of the tsetse gut, the Sodalis-expressed nanobodies were biologically active and bound all over the surface of the parasite. Now that we know this technique works we are looking at making nanobodies which will destroy or block development of the parasite in the tsetse fly gut," Van Den Abbeele, from the Institute of Tropical Medicine, Antwerp, said. However work is still needed to improve and perfect the process as it is still in the developing stage. [7 & 8] Conclusion: In conclusion, I believe that currently the best solution is prevention and control. This is because good control nearly wiped out this disease in the 1960?s. However, relaxing the control meant that the disease reappeared. This method is cost-effective, can be utilised in extremely poor locations and don?t have many implications. The benefits outweigh the risks. I believe that although the main focus should be on prevention and control, drugs are always going to be needed for any who already have the infection or any who may get infected later. Alternative solution 2 was very promising and after the process has been developed and perfected, it may even show promise of a future vaccine to eliminate risk of disease. This could be possible by developing antibodies in humans or injecting them with antibodies to build up immunity. ...read more.

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