Molecular detection and genetic characterization of Giardia duodenalis in temple stray cats in Bangkok, Thailand

Abstract

Introduction Giardia duodenalis is a ubiquitous enteric protozoan infecting humans, domestic animals, and wildlife worldwide. In Thailand, high densities of stray animals represent an important management challenge. However, molecular epidemiological data regarding stray cats remain limited. This study estimated the prevalence of G. duodenalis, characterized the identified genetic assemblages, and explored factors associated with PCR positivity in temple stray cats in Bangkok, Thailand. Methods Fecal samples were collected from 500 stray cats residing across 43 temples in 24 districts of Bangkok. Detection of G. duodenalis was performed using nested PCR targeting the small subunit ribosomal RNA (SSU rRNA) gene. Positive samples were further characterized by genotyping at the glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) loci. Phylogenetic analyses were conducted using the Maximum Likelihood method based on the Tamura 3-parameter model. Associated factors were evaluated using multivariable logistic regression. Results The overall prevalence of G. duodenalis was 10.8% (54/500; 95% CI: 8.4–13.8%), with positive cases identified in 12 of the 24 surveyed districts and 19 of the 43 sampled temples. Eight isolates were successfully genotyped, identifying assemblage B (sub-assemblage BIV, n = 4), assemblage F (n = 3), and assemblage A (sub-assemblage AI, n = 1). The absence of human contact was identified as an exploratory variable associated with higher odds of PCR positivity (adjusted odds ratio [aOR] = 8.80; 95% CI: 2.15–35.98; P = 0.002), while demographic factors (age, sex), geographic zone, and deworming history showed no statistically significant associations. Discussion Assemblages previously reported in humans and various animals were detected among a small number of successfully genotyped isolates, while the source, direction of transmission, and the reservoir status of temple stray cats could not be determined.