Synthesis of Giardia Species and Genotypes in Wild Birds: A Review

Globally, Giardia infections affect an estimated 280 million people each year, making it a significant cause of enteric diarrheal disease. Despite being categorized as a neglected disease, the prevalence of Giardia in wild animals varies, with both mammals and birds serving as hosts. Molecular tools have identified nine Giardia species, including Giardia duodenalis with eight genotypes. Birds, with their wide-ranging habitats and movement capabilities, are crucial disseminators of Giardia. This review aimed to identify Giardia species in wild birds globally, utilizing various academic databases with search terms such as "wild birds" and "Giardia" in combination with Boolean operators for comprehensive results. Giardia spp. have been identified in thirteen orders of wild birds; however, they have been genotyped in only seven orders. Giardia duodenalis assemblage A was identified in wild birds from the Americas; meanwhile, assemblages A, B, D, and F were identified from Europe, and B and E from Asia. Assemblage B is mainly associated with humans and a wide number of wild animals. Therefore, ascertaining the prevalence of G. duodenalis and its assemblages across diverse avian species and orders is crucial to assess the potential risk of zoonotic transmission associated with the dissemination of this protozoan.