Giardia duodenalis genotypes among schoolchildren and their families and pets in urban and rural areas of Sinaloa, Mexico

Introduction: Giardiasis is a human health concern worldwide, especially among schoolchildren. Giardia duodenalis genotypes A and B are infective to humans, but their zoonotic potential remains controversial. In Mexico, the most prevalent genotype is A, but B was also detected in southeastern Mexico. In Sinaloa state, northwestern Mexico, giardiasis is highly prevalent, but Giardia genotypes have been poorly studied. Methodology: This study aimed to investigate the distribution and clinical-epidemiological correlation of G. duodenalis genotypes in schoolchildren and their families and pets in urban and rural areas of Sinaloa state, Mexico. Results: Among 395 schoolchildren (274 urban, 121 rural), 76 (49 urban, 27 rural) were infected with G. duodenalis. In total, 22 families (15 urban, 7 rural) of infected schoolchildren, consisting of 60 family members (41 urban, 19 rural) and 21 pet dogs (15 urban, 6 rural) were examined; 10 family members (5 urban, 5 rural) and 5 pet dogs (3 urban, 2 rural) of 10 families (6 urban, 4 rural) were infected. After PCRRFLP analyses of vsp417 and gdh genes, genotype prevalence among infected urban schoolchildren was 79.5% AI, 12.8% AII, and 7.7% mixed AI+B. However, only AI genotype was found in family members and pets. In the rural area, only the AI genotype was detected. Genotypes were not correlated with clinical manifestations. Conclusions: This paper shows the presence of B genotype in northwestern Mexico for the first time. Detection of AI genotype in dogs suggested the possible role of dogs as the reservoir for human giardiasis in Sinaloa, Mexico.