We found that 0.20 (95% CI 0.14–0.26) of collected stool samples from hospitalized children with diarrhea were positive for Rotavirus. This is considerably lower than previous studies from Iran. A 2014 systematic review on prevalence of Rotavirus infection in Iran showed that Rotavirus infection rates for hospitalized children were slightly higher than outpatients(5). They reported an overall proportion of 0.35 (95% CI, 0.28–0.41) among Iranian children with gastroenteritis with a wide variation between 11.36–79%(5). A 2017 meta-analysis showed a higher overall estimate of about 39%(14). One reason for the difference in our results compared to the overall rates in Iran may be due to the regional epidemiologic differences. Interestingly, low rates of Rotavirus causality in children's diarrhea have been previously reported in central regions of Iran such as Tehran and Esfahan; This in line with the low rate in our study may raise the possibility that the central region of Iran may have lower rates of Rotavirus infection.
Notably, studies from Iran used different techniques in viral isolation and detection from stool samples. This has introduced significant variations in the rates of rotavirus infection across studies owing to difference in accuracy of these methods(1). We detected (20.1%) of diarrhea patients with Rotavirus infection using EIA test although the virus was not found in association with age and gender of the patients.
Also, our study population had a wider age range (1–15 years) than most of previous studies that only included patients younger than 5 years. This factor as well as the decreased chance of RV-related diarrhea as children get older, may account for the apparently lower rate of Rotavirus infection in the current study population.
In spite of the wide age variation in our population, the mean age of patients in the rotavirus-positive group was 2.3 years which was lower than the mean age of the sample. Based on this finding which is consistent with previous findings, we postulate that the likelihood of rotavirus infection is most common in children 2–3 years of age(5, 15, 16).
While most studies have shown a higher rate of Rotavirus infections in colder and dryer seasons with the peak rate happening in Winter(7, 17–19), the Gulf region countries including Iran are an exception showing no distinct peak(20). Our results showed a higher albeit non-significant rate of rotavirus positivity in Winter (33%) among children hospitalized with acute diarrhea without any clear peaks. This lack of significant variation may be due to the hot desert climate in Qom with low rate of rainfalls. The same factor may account for the lower rate found in this study compared with other regions of Iran.
We found significantly lower levels of CRP, ESR, and WBC in patients with rotavirus-related diarrhea compared to rotavirus-negative children. This finding may be due to the higher rate of bacterial infections in rotavirus-negative children hospitalized for diarrhea.
Our study was limited by several factors: we used antigen detection method which has sub-optimal accuracy and did not assess for the genotypic variation of Rotavirus in our population. Also, we did not assess for the etiology of diarrhea in non-rotavirus cases making judgement about the difference in laboratory markers difficult.