Current global status, subtype distribution and zoonotic significance of Blastocystis in dogs and cats: a systematic review and meta-analysis

Abstract

Background Blastocystis is a common intestinal protozoa found in animal and human fecal samples, with over 1 billion individuals infected worldwide. Since domestication, dogs and cats have had a close bond with humans. However, their close proximity poses a potential health risk since they may harbor several zoonotic agents. A global estimate of Blastocystis infection and subtype (ST) distribution in dogs and cats would therefore be of great health importance to humans. Methods We performed a comprehensive systematic search of four English-language databases (PubMed, Scopus, Google Scholar, Web of Science) for relevant articles up to 8 November 2021. The random-effects model was used to make pooled estimates with confidence intervals (CIs). Results In total, we identified 49 publications that met our inclusion criteria and subsequently analyzed the 65 datasets in these articles, of which 23 and 42 datasets were on cats and dogs, respectively. Among the 2934 cats included in the 23 datasets, which involved 16 countries, the prevalence rate of Blastocystis infection was 9.3% (95% CI 5.3–15.9%). The prevalence of Blastocystis infection was slightly lower [7%, 95% CI 4.7–10.4%) among the 7946 dogs included in the 42 datasets, involving 23 countries. The sensitivity analysis showed that no remarkable variation in the estimates upon the stepwise removal of each dataset. Higher ST diversity was found among the examined dogs (ST1-8, ST10, ST23, ST24) than among cats (ST1-4, ST10, ST14). Among dogs, ST3 was the most frequent ST (41.3%), followed by ST2 (39.3%), ST1 (30.9%), ST4 (13.4%), ST8 (12.7%), ST10 (11%) and ST5 (8.1%). Also among dogs, each of ST6, ST7, ST23 and ST24 was observed in only one study. Of the ST found in the cats examined, ST4 (29.5%), followed by ST10 (22.5%), ST1 (19.8%) and ST3 (17.6%) were the most common. A single study also reported the presence of both ST2 and ST14 in cats. With respect to zoonotic Blastocystis STs (ST1–ST9 and ST12), eight were reported from dogs (ST1-ST8) and four were isolated from cats (ST1–ST4), showing the implication of dog and cats in zoonotic transmission. Conclusions Taken together, our results show that elucidation of the true epidemiology and ST distribution of Blastocystis in dogs and cats demands more comprehensive studies, particularly in the negelected regions of the world. Graphical Abstract

Marked genetic diversity within Blastocystis in Australian wildlife revealed using a next generation sequencing–phylogenetic approach

“…The worldwide prevalence of Blastocystis ST3, the most frequent ST in dogs, is 7%, according to a meta-analysis of Blastocystis in dogs ( Shams et al, 2022 ). In the present study, we tested 94 samples from canids (feral dogs, dingo or foxes) and found one test-positive sample (∼1.0%) - a co-occurrence of Blastocystis ST13 and ST46, which is most likely the result of a canine eating a macropod.…”

First molecular characterization of Blastocystis subtypes from domestic animals (sheep and cattle) and their animal‐keepers in Ilam, western Iran: A zoonotic concern

“…ST1–ST32 have been described in many mammalian and avian species. However, based on current criteria for being considered a single ST, a total of 28 STs (ST1 to ST17, ST21, and ST23 to ST32) are generally widely recognized as valid STs (Oliveira‐Arbex et al., 2020; Shams, Shamsi, et al., 2022). Over the past two decades, many epidemiological studies of Blastocystis have demonstrated that most STs have low host specificity.…”

First molecular subtyping and zoonotic significance of Blastocystis sp. in Dromedary (C. dromedarius) and Bactrian (C. bactrianus) camels in Iran: A molecular epidemiology and review of available literature

“…However, the decision to treat the infection is often based on the presence of symptoms and the severity of the infection (Asghari et al., 2019; Rauff‐Adedotun et al., 2023). Asymptomatic carriers may not require treatment unless they are at the risk of transmitting the parasite to others or if the infection is causing complications (Shams, Shamsi et al., 2022; Tantrawatpan et al., 2023). Blastocystis can be transmitted through human‐to‐human, animal‐to‐human, animal‐to‐animal, and human‐to‐animal contact (Asghari, Banavand, et al., 2024).…”