Toxocara in humans, dogs, and cats in Vietnam: A systematic review and meta-analysis

Toxocara spp. are zoonotic parasites that cause toxocariasis in humans. In Vietnam, information on these parasites is fragmented, and many local reports remain inaccessible to the international research community. This study conducted a comprehensive literature review to assess the distribution and prevalence, and to estimate the true prevalence of Toxocara spp. in humans, dogs, and cats in Vietnam. The true prevalence was estimated using a Bayesian approach based on diagnostic test characteristics used in each published study. Of 766 studies screened, 58 studies were included in the systematic review and meta-analysis, including 109,597 humans, 8067 dogs, and 1034 cats. The pooled true prevalence was estimated at 38.5% (95% CI: 31.4-45.5) in humans, 42.3% (95% CI: 30.3-54.2) in dogs, and 50.1% (95% CI: 26.7-73.5) in cats. While numerous studies reported seroprevalence of Toxocara spp. antibodies in humans, data on Toxocara spp. in dogs and cats were limited. ELISA was employed in all included human studies to detect antibodies against Toxocara spp. larvae in humans, and the estimated true prevalence was largely consistent with the apparent prevalence, reflecting the test's assumed accuracy rather than definitive proof. Microscopic examination in dogs and cats likely underestimates the parasite prevalence due to limited sensitivity. The high prevalence of Toxocara spp. in dogs and cats highlights a significant public health concern, particularly given the inadequate management of dog and cat feces. These findings highlight the need for One Health strategies to control Toxocara spp. and reduce its burden in Vietnam.