Low Prevalence of Rotavirus and High Prevalence of Norovirus in Hospital and Community Wastewater after Introduction of Rotavirus Vaccine in Nicaragua

Filemón Bucardo,Lennart Svensson,Johan Nordgren,Per-Eric Lindgren

doi:10.1371/journal.pone.0025962

Filemón Bucardo, Lennart Svensson + Show 2 more

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https://doi.org/10.1371/journal.pone.0025962

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Abstract

Rotavirus (RV) and norovirus (NoV) are major causes of pediatric diarrhea and are altogether associated with approximately 800,000 deaths in young children every year. In Nicaragua, national RV vaccination program using the pentavalent RV5 vaccine from Merck was implemented in October 2006. To determine whether RV vaccination decreased the overall number of RV infections, we investigated the occurrence of RV and NoV in wastewater in the city of León from July 2007 to July 2008 and compared these data with pre-vaccination data. The major finding was the low prevalence of RV compared to NoV in all sampling points (11% vs 44%, p<0.05), and that RV concentration was lower as compared to NoV. RV was observed mainly during the rainy season (July–September), and the majority of all RV detected (6/9) belonged to subgroup (SG) I. The partial VP7-gene obtained from one RV positive sample was similar (99% nt identity) to a G6 VP7-gene of bovine origin and similar to the corresponding gene of the vaccine strain (98%). Furthermore RV G-types 2 and 4 were found in the incoming wastewater. NoV strains were detected throughout the year, of which a majority (20/21) were of genotype GII.4. We conclude that the introduction of RV vaccination reduced the transmission of RV in the community in Nicaragua. However, the burden of diarrhea in the country remains high, and the high prevalence of NoVs in hospital and municipal wastewater is noteworthy. This study highlights the need for further assessment of NoV following RV vaccine introduction.

Highlights

Rotavirus (RV) causes approximately 111 million episodes of diarrhea and is associated with 527,000 deaths in young children every year, predominantly from developing countries
In this study we investigated the prevalence of NoV and RV in hospital and municipal wastewaters in order to understand the transmission of these viruses at community and hospital level following implementation of RV vaccination in Nicaragua
The major novel finding was the low prevalence of RV, further emphasized by the high prevalence of NoVs in both hospital and municipal wastewater

Summary

Introduction

Rotavirus (RV) causes approximately 111 million episodes of diarrhea and is associated with 527,000 deaths in young children every year, predominantly from developing countries. Norovirus (NoV) causes 900,000 clinical visits in industrialized countries and up to 200,000 deaths in children from developing countries [1,2,3]. After safety and efficacy data evaluation of the two licensed RV vaccines (Rotarix and RotaTeq) the World Health Organization (WHO) strongly recommended the inclusion of RV vaccines in the Expanded Program of Immunization (EPI) of vulnerable countries [6]. From October 2006, the RotaTeq vaccine from Merck (RV5) is administered to all Nicaraguan children that are age-eligible. Viral concentration of RV and NoV can range between 16104 and 26107 genome equivalents per liter (g.e l21) of raw wastewater [12,15,16]

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