Explaining Human African Trypanosomiasis (Sleeping Sickness)

Hello everyone, welcome to by Hive blog post. Thanks a lot to everyone who made a comment in my previous post on Ebola Virus. If you haven't read the post, I will be putting the link at the end of this post. You should find time to read it, it is a post worthy of reading. Today, I will be writing on African Trypanosomiasis also known as sleeping sickness which is a protozoan disease. While I was in the boarding house in junior school, there was a fellow student who was always sleeping. He would sleep at every opportunity and most time my teacher would compare him to a Koala bear, or would ask him if he had been beaten by the Tsetse fly.To be candid my school was close to a forest and we always had Tsetse fly visiting, in fact we killed them as a game along with Black fly but trust me when I say the guys sleeping wasn't as a result of Tsetse fly, it could be a disorder or maybe just genetics. Anyways, our teacher always thought he was beating by Tsetse fly.

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African Trypanosomiasis is caused by the protozoan genus Trypanosoma. Like I said in the previous paragraph, it is transmitted by the Tsetse fly but it is transmitted by the fly with the genus Glossina and of the family Glossinidae. In 2020 the number of reported case was at its least, about 700 cases were reported by WHO, this case is the least number reported over years. In 2009, the number of reported case was about 10,000 meaning that this the number of cases has reduced drastically. African Trypanosomiasis can be caused by some species such as Trypasoma brucei rhodesiense (which causes acute African Trypanosomiasis), Trypanosoma brucei gambiense (the conditions are more chronic and last longer such as in cases of the meningoencephalitic stage which can last up to 250 days and it is common in west and central Africa), Trypanosoma brucei brucei, Trypanosoma brucei lewisi, Trypanosoma brucei congolense, and Trypanosoma brucei evansi.

Trypanosoma species are carried by Tsetse fly. When the Tsetse fly bites a person, they inject metacyclic trypomastigotes into the person. When the metacyclic trypomastigotes is in the bloodstream, they become bloodstream metacyclic trypomastigotes which can be carried to sites in the body such as spinal fluid, and the lymphatic system. They multiply by binary fusion in various parts of the body including blood, body fluid, lymph and the spinal fluid. If another Tsetse fly takes a blood meal from another infected person the bloodstream trypasomastigotes transform into procyclic trypomastigotes in the midgut of the Tsetse fly and they multiply by binary fusion. They transform into epimastigotes goes into the salivary gland of the Tsetse fly and multiplies, after which they transform into metacyclic trypomastigotes, and the matacyclic trypomastigotes infects another person when the Tsetse fly bites another person.

When a person is infected by the trypanosoma species, the person poccesses an innate immunity through the Apolipoprotein L-1 (APOL1). When the Trypanosoma engulfs the Apolipoprotein, it destroys the organism. Trypanosoma can avoid humoral immunity as it can switch its VSG periodically through its glycoprotein.

Symptoms of African Trypanosomiasis can be divided into three stages which are;

Stage 1 (Early infection)
Symptoms include Trypanosomal chancre which usually occurs within one week after bite which is usually painful, Rash which usually occurs within weeks after the infection, and when in the lymphatic system they can cause lymphadenitis.

Stage 2 (Late Infection)
This is the stage when it reaches the Central nervous system. When there is an increased white blood cell in the cerebral spinal fluid, and it could lead to progressive diffuse meningoencephalitis, Meningeal inflammatory infiltrates, as well as widespread focal white matter demyelination. The symptoms would include headaches, personality changes, difficulty concentrating and completing comples tasks, Tremor, Ataxia, psychosis, alterations in circadian rhythm, daytime somnolence (continuous daytime sleep) which could lead to Comatose.

Diagnosis of African Trypanosomiasis includes Blood smear, Tissue aspirate, spinal pap used to look at the Cerebrospinal fluid for trypanosoma in the fluid, serology can also be performed, PCR can also be done. Treatment can vary depending on the type of trypanosoma and the stages. In cases of T. Brucei Gambiense, if it is in the early stage of infection treatments such as Pentamidine, and Suramin can be used. In the late stages, Eflornithine, and Nifurtimox can be used since it crosses the blood brain barrier to treat as it involves the CNS. In the case of the early stage of T.brucei Rhodesiense infection, Suramin can be used, and in the late stages of the infection which involves the Central Nervous System, Melarsoprol can be used.

Conclusion

Human African Trypanosomiasis known as sleeping sickness is caused by Trypasoma brucei rhodesiense, and Trypanosoma brucei gambiense, while other species cause diseases in animal and occasionally causes diseases in humans. Chagas Disease known as American Trypanosomiasis is caused by trypanosoma cruzi which is different from the other Trypanosoma species which causes Human African Trypanosomiasis. I will be writing about American Trypanosomiasis in my next post.

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https://www.msdmanuals.com/professional/infectious-diseases/extraintestinal-protozoa/african-trypanosomiasis

https://www.cdc.gov/parasites/sleepingsickness/index.html

https://www.sciencedirect.com/science/article/pii/S2212963414000126

https://www.who.int/news-room/fact-sheets/detail/trypanosomiasis-human-african-(sleeping-sickness)

https://www.intechopen.com/chapters/65773

https://www.britannica.com/science/sleeping-sickness

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3493381/

https://www.cdc.gov/parasites/sleepingsickness/disease.html