Editing Tsetse fly (section)

=== In humans ===
{{main article|African trypanosomiasis}}
Human African trypanosomiasis, also called [[African trypanosomiasis|sleeping sickness]], is caused by trypanosomes of the species ''Trypanosoma brucei''. This disease is invariably fatal if left untreated, but can almost always be cured with current medicines if the disease is diagnosed early enough.

Sleeping sickness begins with a tsetse bite leading to an inoculation in the subcutaneous tissue. The infection moves into the [[lymphatic system]], leading to a characteristic swelling of the lymph glands called ''Winterbottom's sign''.<ref>{{Cite web|url=https://sc.edu/study/colleges_schools/medicine/education/basic_science_departments/pathology_microbiology_and_immunology/index.php|title=Pathology, Microbiology and Immunology - School of Medicine {{pipe}} University of South Carolina|website=Sc.edu|access-date=12 November 2020}}</ref> The infection progresses into the blood stream and eventually crosses into the [[central nervous system]] and invades the [[brain]] leading to extreme [[lethargy]] and eventually to [[death]].

The species ''Trypanosoma brucei'', which causes the disease, has often been subdivided into three subspecies that were identified based either on the vertebrate hosts which the strain could infect or on the virulence of the disease in humans. The trypanosomes infectious to animals and not to humans were named ''Trypanosoma brucei brucei''. Strains that infected humans were divided into two subspecies based on their different virulences: ''Trypanosoma brucei gambiense'' was thought to have a slower onset and ''Trypanosoma brucei rhodesiense'' refers to strains with a more rapid, virulent onset. This characterization has always been problematic but was the best that could be done given the knowledge of the time and the tools available for identification. A recent molecular study using [[restriction fragment length polymorphism]] analysis suggests that the three subspecies are [[polyphyletic]],<ref>{{cite journal |author=G. Hide |year=1999 |title=History of Sleeping Sickness in East Africa |journal=[[Clinical Microbiology Reviews]] |volume=12 |issue=1 |pages=112–125|doi=10.1128/CMR.12.1.112 |pmid=9880477 |pmc=88909 |doi-access=free }}</ref> so the elucidation of the strains of ''T. brucei'' infective to humans requires a more complex explanation. [[Procyclin]]s are [[protein]]s developed in the surface coating of trypanosomes whilst in their tsetse fly vector.<ref>{{Cite journal|doi=10.1073/pnas.98.4.1513 |pmid=11171982|title=The surface coat of procyclic Trypanosoma brucei: Programmed expression and proteolytic cleavage of procyclin in the tsetse fly|year=2001|last1=Acosta-Serrano|first1=A. |last2=Vassella|first2=E.|last3=Liniger|first3=M.|last4=Renggli|first4=C. K.|last5=Brun|first5=R. |last6=Roditi|first6=I.|last7=Englund|first7=P. T.|journal=Proceedings of the National Academy of Sciences |volume=98|issue=4|pages=1513–1518 |bibcode=2001PNAS...98.1513A|pmc=29288|doi-access=free}}</ref>{{clarify |reason=This seems unrelated. Are these molecules the sequencing targets that suggested ''brucei'' is not one species? Otherwise why is this mentioned here. |date=October 2020}}

Other forms of human trypanosomiasis also exist but are not transmitted by tsetse. The most notable is American trypanosomiasis, known as [[Chagas disease]], which occurs in [[South America]], caused by ''Trypanosoma cruzi'', and transmitted by certain insects of the [[Reduviidae]], members of the [[Hemiptera]].