Molecular seasonality of Giardia lamblia in a cohort of Egyptian children: a circannual pattern.

Giardia lamblia (G. lamblia) is the most worldwide prevailing intestinal parasite, notorious for its broad range of seasonal and age-related prevalence. The potentially lethal nature of giardiasis makes it essential that the seasonality, the groups at risk, and other potential risk factors are identified. The present molecular epidemiological study was designed to determine the genetic diversity of G. lamblia infection, taking into account seasonal peaks, age distribution, and associated symptoms in a cohort of Egyptian diarrheic patients. Stool samples were collected from 1187 diarrheic patients attending outpatient clinics of Cairo University hospitals, of all age groups over a 12-month period. The patients were examined microscopically for fecal G. lamblia cysts, and/or trophozoites, and for copro-DNA detection using nested polymerase chain reaction (nPCR) assays targeting beta giardin gene. PCR-positive samples were characterized molecularly by nPCR restriction fragment length polymorphism (RFLP) to determine Giardia assemblages. The findings revealed circannual prevalence of Giardia, with a seasonal pattern peaking in mid-summer and late winter, with the summer peak preceded by a peak in temperature. Infection was prevailing in 224 (18.9 %) cases, mainly assemblage B (81.2 %) followed by assemblage A (18.8 %). There were statistically significant associations between the detection of Giardia and flatulence, persistent diarrhea, vomiting, and abdominal pain, while gender and intermittent diarrhea showed no association. The pre-school age group was the most vulnerable. This is the first study of molecular characterization of Giardia to determine its circannual prevalence in Egypt, a finding which carries promising potential for the diagnosis, treatment, and elimination of the disease.