Environmental factors associated with childhood norovirus diarrhoea in León, Nicaragua.

Norovirus is detected in one in five diarrhoea episodes in children, yet little is known about environmental risk factors associated with this disease, especially in low-income settings. The objective of this study was to examine environmental risk factors, and spatial and seasonal patterns of norovirus diarrhoea episodes in children in León, Nicaragua. We followed a population-based cohort of children under age 5 years for norovirus diarrhoea over a 1-year period. At baseline, characteristics of each household were recorded. Households were geocoded and spatial locations of garbage dumps, rivers, and markets were collected. In bivariate analysis we observed younger children and those with animals in their households were more likely to have experienced norovirus episodes. In adjusted models, younger children remained at higher risk for norovirus episodes, but only modest associations were observed with family and environmental characteristics. We next identified symptomatic children living in the same household and within 500 m buffer zones around the household of another child infected with the same genotype. Norovirus diarrhoea episodes peaked early in the rainy season. These findings contribute to our understanding of environmental factors and norovirus infection.

Seroprevalence in Household Raised Pigs Indicate High Exposure to GII Noroviruses in Rural Nicaragua.

Information about porcine norovirus (PoNoV), genetically similar to human NoV (HuNoV), is limited from rural areas where household-raised pigs are heavily exposed to faecal material which could facilitate transmission. Histo-blood group antigens (HBGAs) are known susceptibility factors to NoV in humans and in a germfree piglet model but their role in susceptibility in the porcine population remains unknown. This study reports: (i) the seroprevalence and antibody titres to human norovirus (NoV) VLPs in household raised pigs; (ii) the distribution of HBGAs in relation to NoV IgG antibody titres and further characterization by blocking of GII.4 VLP binding to pig gastric mucins (PGM). The majority of pigs were seropositive to all three VLPs tested (58-70%) with seropositivity and cross-reactivity increasing significantly with age. However, pig sera could not block the binding of NoV GII.4 VLPs (Dijon) to PGM suggesting no previous infection with this genotype. The majority of the pigs were H-positive (84%), a susceptibility factor for human infections. IgG antibody titres were however higher in H-negative (GMT = 247) as compared with H-positive (GMT = 57) pigs, but after age stratification, this difference in antibody titres was only observed in pigs ≤1 month of age. In conclusion, serological data show that the porcine population of Nicaragua is highly exposed to NoV infections, and the association to HBGAs warrants further investigation.

Emergence of a novel GII.17 norovirus ­ End of the GII.4 era?

In the winter of 2014/15 a novel GII.P17-GII.17 norovirus strain (GII.17 Kawasaki 2014) emerged, as a major cause of gastroenteritis outbreaks in China and Japan. Since their emergence these novel GII.P17-GII.17 viruses have replaced the previously dominant GII.4 genotype Sydney 2012 variant in some areas in Asia but were only detected in a limited number of cases on other continents. This perspective provides an overview of the available information on GII.17 viruses in order to gain insight in the viral and host characteristics of this norovirus genotype. We further discuss the emergence of this novel GII.P17-GII.17 norovirus in context of current knowledge on the epidemiology of noroviruses. It remains to be seen if the currently dominant norovirus strain GII.4 Sydney 2012 will be replaced in other parts of the world. Nevertheless, the public health community and surveillance systems need to be prepared in case of a potential increase of norovirus activity in the next seasons caused by this novel GII.P17-GII.17 norovirus.

Large increase of rotavirus diarrhoea in the hospital setting associated with emergence of G12 genotype in a highly vaccinated population in Nicaragua.

Rotaviruses (RVs) are a major cause of severe diarrhoea in young children. Nicaragua introduced routine immunization with the pentavalent RV vaccine (RV5) in 2006, which greatly reduced the incidence of diarrhoea. A remaining concern has been the possible emergence of new RV strains to which the vaccination has less effect. In this study, 837 children with diarrhoea in hospital settings were investigated for RV between May 2011 and July 2013. RVs were subsequently typed by multiplex PCR and/or sequencing. Fecal anti-RV IgA titres for a subset of RV-infected (n = 137) and noninfected children (n = 52) were determined with an in-house enzyme-linked immunosorbent assay. The RV detection rate was 8% in 2011, followed by a sharp increase to 29% in 2012 and 19% in 2013. This was associated with emergence and predominance of genotype G12 RV, from 0% in 2011 to 66% in 2012 and 82% in 2013, infecting children from 1 month to 10 years of age. Two sequenced G12 strains showed a Wa-like genome with genotype G12-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1, similar to the globally emerging G12 strains. Fecal anti-RV IgA analysis showed that most G12-infected and noninfected children had been in contact with either vaccine or wild RV strains, but such antibodies did not prevent symptomatic G12 infection. A marked increase of RV was evident in the hospital setting associated with a nationwide emergence and predominance of RV G12 genotype in a population with high RV5 vaccine coverage.

The seroprevalence of Taenia solium cysticercosis among epileptic patients in León, Nicaragua, as evaluated by ELISA and western blotting.

The Taenia solium taeniasis/cysticercosis complex is an important public-health problem in several countries, where many epileptic seizures appear to be associated with neurocysticercosis. As few data on this problem in Nicaragua exist, the seroprevalence of antibodies reacting with antigens from T. solium cysticerci was investigated among 88 Nicaraguan epileptics (45 males and 43 females, aged 6-53 years). In questionnaire-based interviews, each adult subject and a caregiver of each child investigated were asked about potential risk factors for taeniasis/cysticercosis. When a serum sample from each subject was then checked for anti-cysticercus antibodies, 8.0% of the subjects were found seropositive by ELISA and 14.8% by western blotting. Five samples (all from individuals who had been epileptic for > 5 years) were positive in both tests. When the level of association between each potential risk factor and seropositivity (in ELISA or by blotting) was evaluated, the only statistically significant association detected was that between a positive ELISA and the subject living in a household where pigs were raised (odds ratio = 5.18; 95% confidence interval = 0.8-41.6; P = 0.05). The bands most frequently recognized in the western blots (of 50, 42-39, 24 and 14 kDa) were those previously reported. The results indicate that, in the city of Léon, cysticercosis may be endemic and the cause of a significant proportion of the epilepsy recorded.