RE: The burden of Rotavirus gastroenteritis among hospitalized pediatric patients in a tertiary referral hospital in Jeddah.

To the Editor: I have 2 comments on the interesting paper by Afifi and Nabiha.1

First, despite the implementation of Rotavirus (RV) vaccine in Saudi Arabia in 2006, the prevalence of RV gastroenteritis (RVGE) (42.9%) reported by Afifi and Nabiha1 is still worrisome. I presume that that the worrying prevalence can be attributed to the following 2 points: (1) Saudi pediatric population is not yet completely covered with RV vaccine. This is obvious on noticing that only 2.3% of the studied RV positive GE and 6.1% of the studied RV negative GE received RV vaccine (Table 1).1 (2) It is obvious that temporal and spatial fluctuations in the genotype distribution of human RV are continuously observed worldwide in surveillance studies. New genotypes, such as G9 and G12, have emerged and spread worldwide in a very short time span. In addition, reassortment events have the potential to contribute substantially to genetic diversity among human and animal RV.2 Recent data on the molecular epidemiology of RVGE in Saudi children are scarce. Kheyami3 addressed the distribution of G and P types of RV circulating in the population of Saudi Arabia and demonstrated the presence of serotypes G1-G4, G9, G12, P [4], P [6], and P [8]. However, Obeid4 in his study found that subgroup I (serotype 2) constituted 5.4% of the isolates in comparison to 56.7% for subgroup II (serotypes 1, 3, and 4), whereas 37.8% were nontypeable. Regular surveillance and characterization of RV are, therefore, warranted to confirm RV genotype fluctuations. This, in turn, might partly explain the prevalence of RVGE in Saudi children compared to other viruses. It also helps identify unusual types that could be incorporated into future RV vaccines.

Second, Norovirus (NV) is currently recognized as one of the emerging viruses causing infection in humans. It is the leading cause of the outbreaks of viral GE worldwide. In children, NV plays an increasing and important role in enteric infection, apart from RV, especially in the post-RV vaccine era.5 Afifi and Nabiha1 categorized their studied GE cases into 4 groups: RV infection alone (33.6%), adenovirus (AV) infection alone (7%), combined RV and AV infection (9.3%), and other causes of GE (50.2%). I wonder whether they detected the cases of NVGE in their studied cohort and probably included them within the latter group. This is critical to comment that NVGE shares many characteristics of RVGE, namely similar clinical presentation, significant morbidity, mortality and economic burden, and the need for regular molecular and genetic surveillance of the circulating virus.