Authors

Discussion

Introduction: African trypanosomiasis is a protozoan disease of Trypanosome origin. It is mainly transmitted by tsetse flies. This disease is a major concern in sub-Saharan Africa, with detrimental effects on both human and animal health and causing significant losses to affected countries. Both Animal African Trypanosomiasis (AAT) and Human African Trypanosomiasis (HAT) are present in Malawi with cases reported in the districts of Rumphi, Nkhotakota and Kasungu where large national parks exist. HAT in Malawi is caused by Trypanosoma brucei rhodesiense and is transmitted by the tsetse fly usually Glossina morsitans and Glossina pallidipes.

For over ten years our NTD group has assessed the presence of trypanosomiasis in the named districts with emphasis on tsetse fly infectivity and human trypanosomiasis prevalence.  Here we report a decade’s trend of trypanosomiasis in Malawi.

Methods: Since 2012, we conducted xenomonitoring surveys, human active and passive surveillance and hospital archive case retrievals in Rumphi, Nkhotakota, Kasungu and Liwonde.

Xenomonitoring: assessing if the species of tsetse flies that inhabit the nature reserves in these districts harbour T. b. rhodesiense. Tsetse flies were collected using Mzee traps, identified and dissected and microscopically examined for parasites. DNA was also extracted and PCR (TBR & SRA) conducted to identify the species.

Human surveillance: communities bordering the nature reserves were surveyed, blood was collected and microscopically checked for parasites. PCR was also done to identify the species.

Mapping: retrospective case finding was done from hospital archives. All villages where the cases came from were located, GPS coordinated taken and spatial maps were drawn.

Results: We have detected 7 species of Trypanosomes in the tsetse fly of Malawi (T. brucei, T. vivax, T.godfrey, T.simaetsayo, T. simae, T. congolense savanna and T.b.rhodesiense). T.b.rhodesiense was detected in all the sites. There was an increase of rHAT in Nkhotakota and Rumphi which is now declining with a total of 18 cases in 2012 and as high as 90 cases in 2019. Almost 70% of HAT cases were men. An outbreak of rHAT was noted from 2019 to 2020. Asymptomatic Human cases were observed in Liwonde but not in the other sites. Rumphi and Nkhotakota showed clustered rHAT cases within a 10km range from the nature reserves.

Conclusion: HAT is still prevalent in Malawi with cases being reported in Rumphi and Nkhotakota. Clustered HAT cases show a possible targeted intervention which is cost effective and area specific. Further study’s in AAT is currently underway.