Molecular epidemiology and host genetics of norovirus and rotavirus infections in Portuguese elderly living in aged care homes

Abstract

Norovirus (NoV) and rotavirus group A (RVA) are major agents of acute gastroenteritis worldwide. This study aimed to investigate their epidemiological profile in Portuguese elderly living in long‐term care facilities and to assess the host genetic factors mediating infection susceptibility. From November 2013 to June 2015, 636 faecal specimens from 169 elderly, mainly asymptomatic, living in nursing homes in Greater Lisbon and Faro district, Portugal, were collected. NoV and RVA were detected by real‐time polymerase chain reaction and NoV genotyped by phylogenetic analysis. NoV detection rate was 7.1% (12 of 169). Three GI.3 and one GII.6 strains were genotyped. RVA detection rate was 3.6% (6 of 169), exclusively in asymptomatic individuals. Host genetic factors associated with infection susceptibility were described on 250 samples by saliva‐based enzyme‐linked immunosorbent assays. The Lewis‐negative phenotype was 8.8% (22 of 250) and the rate of nonsecretors was 16.8% (42 of 250). Association to NoV and RVA infection was performed in the subgroup of individuals (n = 147) who delivered both faecal and saliva samples. The majority of NoV‐ and RVA‐positive individuals (90.9% and 83.3%, respectively) were secretor‐positive, with Lewis B phenotype. In a subset of individuals, FUT2 and FUT3 genes were genotyped to assess mutations and validate the secretor and Lewis phenotypes. All sequenced nonsecretors were homozygous for FUT2 nonsense mutation G428A. In this study, low detection rates of NoV and RVA infections were found during two winter seasons. However, even in the absence of any outbreak, the importance of finding these infections in a nonepidemic situation in long‐term care facilities may have important implications for infection control.

The Impact of Human Genetic Polymorphisms on Rotavirus Susceptibility, Epidemiology, and Vaccine Take

“…A simplified rough estimation of Lewis status in different geographical settings (~7.5%, 20%, and 33% in Europe/North America, Central America/Asia, and Sub-Saharan Africa, respectively). The proportion of Lewis-negatives vary widely between populations [12,15,16,23,[26][27][28]. Lewis-negative individuals are susceptible to P [6] rotavirus infections, and the relative proportion of P [6] rotavirus infections in a population correspond reasonably well to the proportion of Lewis-negatives in that population.…”

“…More studies are warranted to understand if and how HBGA phenotype distribution affects rotavirus disease burden at population level. [12,15,16,22,23,[26][27][28]. Studies have suggested that non-secretors have a lower vaccine response but would also be protected against circulating wildtype strains of the same genotypes which predominantly infect secretors.…”

Epidemiology of GII.4 and GII.2 norovirus outbreaks in closed and semi-closed institutions in 2017 and 2018

“…Studies have shown that a large percentage of infections caused by norovirus occur in the winter months 18 – 21 , although other studies did not observe this 22 . We found 63.9% of outbreaks occurred in the winter months, but many outbreaks were also detected in the warmer months, which occurred mainly in places where there is more movement of people, such as hotels and summer camps.…”