Asymptomatic norovirus infections in Nicaraguan children and its association with viral properties and histo-blood group antigens.
BACKGROUND
It has been previously reported that histo-blood group antigens (HBGAs) and particularly secretor status provides protection against symptomatic norovirus infection, but it remains unclear to what extent this includes asymptomatic infections in children.


METHODS
To explore whether HBGAs or certain viral genotypes are associated with asymptomatic norovirus infections in a pediatric population in Nicaragua, we investigated 163 children ≤5 years of age, without a recent history of diarrhea (≤10 days).


RESULTS
Asymptomatic norovirus infections were observed in 11.7% (19/163), with children ≤6 months of age being most frequently infected (16%). Of the 19 norovirus-positive children, 4 (21%) and 10 (53%) were infected with genogroups GI and GII, respectively, and 4 children (21%) were infected with viruses of both genogroups. Most children had ≥10 viral genomes per gram of feces. Nucleotide sequence analysis (15/19) revealed uncommon genotypes, such as, GII.7 (n = 5) and GII.2 (n = 3). An interesting observation was the low frequency of norovirus GII.4 strains among the asymptomatic children. AB blood type, Lewis a (Le) phenotype and nonsecretor genotype (sese) were not found among the asymptomatic children, but they occurred in population controls.


CONCLUSIONS
Frequency of asymptomatic norovirus infections was similar to that observed in symptomatic children from Nicaragua. Norovirus GII.2 and GII.7 were frequently detected but the globally dominating GII.4 was infrequent. Host genetic factors previously observed to be associated with protection against symptomatic norovirus infection were not found in this study.
Bucardo
Filemon
F
Department of Microbiology, University of León, UNAN-León, Nicaragua.
Nordgren
Johan
J
Carlsson
Beatrice
B
Kindberg
Elin
E
Paniagua
Margarita
M
Möllby
Roland
R
Svensson
Lennart
L
D058345:Asymptomatic Infections / Q000453:epidemiology*; D001789:Blood Group Antigens / Q000032:analysis*; D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology*; D002675:Child, Preschool; D005243:Feces / Q000821:virology; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009527:Nicaragua; D029322:Norovirus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D015995:Prevalence
D001789:Blood Group Antigens