Dear Editor,
We read the article entitled “Human Schistosomiasis due to Schistosoma bovis in Nigeria” by Enudi et al., published in The American Journal of Tropical Medicine and Hygiene.1
In the article, an S. bovis cytochrome c oxidase subunit 1 (COX1) gene profile was identified in a pool of eggs from a human sample. It was suggested that S. bovis could infect human beings. Unfortunately, the authors did not include a nuclear marker in their genetic analysis. The authors also used a pool of S. haematobium eggs for DNA extraction. Ideally, a single egg is more appropriate to avoid genotyping a mixed Schistosoma species infection.
The inference that S. bovis was the causative agent of human schistosomiasis was based on an incomplete dataset. Schistosoma bovis COX1 profiles have previously been identified in samples from Nigeria2,3 and other parts of Africa alongside an S. haematobium internal transcribed spacer (ITS) profile representing mitonuclear discordance, resulting from either ancient or extant hybridization between S. bovis and S. haematobium.4 It is also important to highlight that two mitotypes, S. bovis and S. haematobium, can sometimes be recorded in S. haematobium populations, particularly in West Africa.2,5,6
Although the COX1 and ITS markers are traditionally used to genotype Schistosoma species, there are suggestions that the markers are inadequate, and scientists genotyping based on the two markers alone should interpret their results with caution.2,6 Therefore, the title and conclusion of the article are potentially misleading without the nuclear marker profile for the sample reported.
REFERENCES
- 1.↑
Enudi AO, Nmorsi OPG, Egwunyenga AO, 2024. Human Schistosomiasis due to Schistosoma bovis in Nigeria. Am J Trop Med Hyg 111: 1230–1236.
- 2.↑
Ajakaye OG, Enabulele EE, Balogun JB, Oyeyemi OT, Grigg ME, 2024. Extant interspecific hybridization among trematodes within the Schistosoma haematobium species complex in Nigeria. PLoS Negl Trop Dis 18: e0011472.
- 3.↑
Onyekwere AM, Rey O, Allienne JF, Nwanchor MC, Alo M, Uwa C, Boissier J, 2022. Population genetic structure and hybridization of Schistosoma haematobium in Nigeria. Pathogens 11: 425.
- 4.↑
Rey O, Webster BL, Huyse T, Rollinson D, Van den Broeck F, Kincaid-Smith J, Onyekwere A, Boissier J, 2021. Population genetics of African Schistosoma species. Infect Genet Evol 89: 104727.
- 5.↑
Agniwo P et al., 2023. Genetic profiles of Schistosoma haematobium parasites from Malian transmission hotspot areas. Parasit Vectors 16: 263.
- 6.↑
Platt RN 2nd et al., 2024. Genomic data reveal a north-south split and introgression history of blood fluke (Schistosoma haematobium) populations from across Africa. bioRxiv [Unreviewed Preprint]. doi: 10.1101/2024.08.06.606828.