Prevalence and Genetic Diversity of Blastocystis sp. in Humans, Dogs and Cats in Gabon: A One Health Perspective.

INTRODUCTION

Blastocystis sp. is a cosmopolitan protist that colonises the gastrointestinal tract of mammals, including humans, dogs and cats. Although its pathogenicity remains debated, Blastocystis sp. has been linked to gastrointestinal symptoms and alterations in the gut microbiota. In Gabon, most epidemiological data on Blastocystis sp. rely on microscopy, which may underestimate true prevalence. Moreover, molecular studies remain scarce, and none have investigated the parasite's presence in domestic animals. This study aimed to estimate the prevalence and subtype (ST) distribution of Blastocystis sp. in humans, dogs and cats across three provinces of Gabon, within a One Health framework.

METHODS

Between June 2021 and November 2022, a total of 182 faecal samples were collected: 127 from children in the Mulundu department (Ogooué-Lolo), 55 from both dogs and cats in Libreville (Estuaire) and Franceville (Haut-Ogooué). Samples were screened for the presence of Blastocystis sp. using conventional PCR targeting the SSU rRNA gene, positive isolates were subtyped.

RESULTS

Blastocystis sp. was detected in 58.3% of human samples, with a significant association between infection and place of residence (p = 0.02, fisher's exact test). Among animals, the parasite was found in 18.2% (8/44) of dogs and 36.4% (4/11) of cats. Subtyping revealed ST1 and ST3 in humans, while only ST1 was found in dogs. No subtypes were resolved in cats. These findings confirm the high circulation of Blastocystis sp. in both humans and domestic animals in Gabon and highlight the potential for zoonotic transmission.

CONCLUSION

This study provides the first molecular evidence of Blastocystis sp. infection in animals in Gabon and underscores the need for integrated surveillance strategies to better understand its epidemiology.