Allergic reactions associated with tsetse fly bites.
Allergic reactions in response to arthropod bites are a growing concern worldwide. Alpha-Gal syndrome (AGS) is a red meat allergy associated with IgE antibodies against galactose-alpha-1,3-galactose (alpha-Gal), typically linked to tick bites but other arthropods may also play a role. The objective of this study was to investigate the potential association between tsetse fly ( spp.) bites and AGS by analyzing clinical cases, citizen science data, and the possible production of alpha-Gal by tsetse flies. Data from five case series involving tsetse fly bites included demographic information such as age, gender and geographical location, as well as clinical details like symptoms and diagnosis. The production of alpha-Gal by tsetse flies focused on epitope content analysis by ELISA and the expression of several galactosyltransferases using RT-qPCR in the whole body of Ugandan tsetse flies and midgut tissues. The cases included patients bitten by tsetse flies in Uganda-Rwanda and, with different symptoms. Individuals resided in Spain, the USA or Uganda, with no record of or reaction to bites from ticks or other arthropods. Cases 1 and 2 were diagnosed with AGS, whereas Ugandan Case 3 presented symptoms consistent with AGS. Ugandan participative or citizen science survey identified one individual (Case 4) who experienced allergic reactions to red meat following multiple tsetse fly bites, while eight individuals (summarized as grouped Case 5) exhibited only local skin reactions to several bites. The expression of galactosyltransferases suggested the possible production of alpha-Gal modification in these arthropods. Allergic anaphylactic reactions to tsetse fly bites may occur in some individuals, potentially linking tsetse fly bites to AGS. Diagnosis and monitoring should consider factors beyond anti-alpha-Gal IgE antibody levels, such as arthropod salivary compounds and human immune biomarkers.