Report of Giardia assemblages and giardiasis in residents of Guilan province-Iran.

Giardia duodenalis is considered a highly diverse organism that infects a variety of mammalian hosts. Giardiasis is a significant public health problem in Iran. The purpose of this study was to investigate the occurrence of Giardia duodenalis (G. lamblia, G. intestinalis) infections in humans residing in the Guilan province of Iran. Stool samples were collected during 12 months from 8356 individuals that had been referred to certain hospitals in the capital city of Rasht in the Guilan province, of which 4126 were males and 4230 were females. The samples were separated into three groups according to patient age: group A 1-9 years old (n = 483); group B 10-19 years old (n = 491); and group C greater than 20 years old (n = 7382). The wet mount technique was performed directly on 8356 fecal samples for microscopy. Samples were examined using a saline and iodine direct smear technique in order to confirm the presence of G. duodenalis. The results indicated that 2.5% (206/8356) of the samples were identified as positive for G. duodenalis. A total of 30% of the infected patients (n = 62) had no symptoms. In symptomatic cases, the most common symptoms (46%, n = 95) were abdominal cramps and bloating. Twenty-four percent of patients (n = 50) had cramps, bloating, nausea, and diarrhea. Sixty positive samples were sent for G. duodenalis genotyping based on the amplification of the gdh gene. Forty-one PCR products were successfully selected and sequenced, where 38 (92.6%) samples were identified as genotype A/subgenotype II and in three samples (7.4%) genotype B/subgenotype IV. Genotype A-II had a dominant prevalence as compared to the genotype B-IV samples that were identified in the study. Based on the samples provided by the regional teaching hospitals and subsequent sample analysis, the authors concluded that assemblage A-II is most likely the most common Giardia subgroup infection in the Guilan region. Assemblages have been reported in both humans and animals; however, further studies need to investigate the role of domestic animals and water reservoirs as potential sources of Giardia infection in the Guilan region.