Molecular Detection of Norwalk Virus in Carp Fish and Shrimp Ponds in Khuzestan Province, Iran by RT-PCR Method

Abstract

Background: Norwalk virus is one of the most common causes of viral gastroenteritis. The aquatic products are potential sources of contamination with this virus. Objectives: The main objective of the study was to investigate the presence of the Norwalk virus in different aquatic animals in Khuzestan provinces, Iran. Materials and Methods: A total of 40 pieces of fish (silver carp, common carp, big head, and grass carp species) and 10 pieces of shrimps were caught from ponds, and the samples were transferred to the laboratory in ice bags. After the separation of the intestine, the content of the intestine was extracted using two sterile filters. Then, the supernatant was used for reverse transcription polymerase chain reaction (RT-PCR) using Calicivirus-specific primers (p289/ p290). Then, Norwalk virus-specific primers (NVp36/NVp35) were detected in Calicivirus positive samples. Results: The results showed 8% (4 samples) and 6% (3 samples) of the samples were infected with Calicivirus (p289/p290 genes) and Norwalk virus (NVp36/NVp35 genes), respectively. Calicivirus positive samples included 2 common carp, 1 silver carp, and 1 shrimp. Norwalk virus-positive samples included 2 common carp and 1 shrimp. In other words, the highest prevalence of virus was observed in aquatic fish feeding from the bottom of the pool. Due to the fact that this species is bred with other species and considering that this virus lives in the gastrointestinal tract, the ingestion of feces of other infected organisms can lead to the increase of this virus in the digestive system of carp. Conclusion: Therefore, due to the importance of Norwalk as a zoonotic agent and the possibility of human infection through consumption of aquatic products, preventive measures such as not using animal manure for fertilization and preventing the growth of phytoplankton in aquaculture ponds and cooking meat properly are suggested.