Abstract
BackgroundAvian rotaviruses (RVs) cause gastrointestinal diseases of birds worldwide. However, prevalence, diversity, epidemiology and phylogeny of RVs remain largely under-investigated in Africa.MethodsFecal samples from 349 birds (158 symptomatic, 107 asymptomatic and 84 birds without recorded health status) were screened by reverse transcription PCR to detect RV groups A and D (RVA and RVD). Partial gene sequences of VP4, VP6, VP7 and NSP4 for RVA, and of VP6 and VP7 for RVD were obtained and analyzed to infer phylogenetic relationship. Fisher’s exact test and logistic regression were applied to identify factors potentially influencing virus shedding in chickens.ResultsA high prevalence of RVA (36.1%; 126/349) and RVD (31.8%; 111/349) shedding was revealed in birds. In chickens, RV shedding was age-dependent and highest RVD shedding rates were found in commercial farms. No negative health effect could be shown, and RVA and RVD shedding was significantly more likely in asymptomatic chickens: RVA/RVD were detected in 51.9/48.1% of the asymptomatic chickens, compared to 18.9/29.7% of the symptomatic chickens (p < 0.001/p = 0.01). First RVA sequences were obtained from mallard ducks (Anas platyrhynchos) and guinea fowls (Numida meleagris). Phylogenetic analyses illustrated the high genetic diversity of RVA and RVD in Nigerian birds and suggested cross-species transmission of RVA, especially at live bird markets. Indeed, RVA strains highly similar to a recently published fox rotavirus (RVA/Fox-tc/ITA/288356/2011/G18P[17]) and distantly related to other avian RVs were detected in different bird species, including pigeons, ducks, guinea fowls, quails and chickens.ConclusionThis study provides new insights into epidemiology, diversity and classification of avian RVA and RVD in Nigeria. We show that cross-species transmission of host permissive RV strains occurs when different bird species are mixed.
Highlights
Avian rotaviruses (RVs) cause gastrointestinal diseases of birds worldwide
Rotavirus shedding In total, 36.1% (126/349, 95% CI: 31–41%) and 31.8% (111/349, 95% CI: 27–37%) of all fecal samples were positive for avian Rotavirus group A (RVA) and RVD (Table 1)
RVA and RVD co-infection was revealed for 15.2% (53/349, 95% CI: 12–19%) of the birds
Summary
Avian rotaviruses (RVs) cause gastrointestinal diseases of birds worldwide. Rotavirus (RV) infections are highly prevalent worldwide [1] and cause gastroenteritis mainly in infants [2] and young animals (reviewed in [3]). Different bird species are susceptible to RV infections ([4]; reviewed in [5]). The genome of these non-enveloped, double-stranded RNA viruses is composed of 11 segments, encoding six viral structural proteins (VP1 to VP4, VP6, and VP7) and five to six nonstructural proteins (NSP1 to NSP5/ NSP6). Eight RV groups A to H (RVA-RVH) are defined by the International Committee on Taxonomy of Viruses (ICTV) based mainly on group-specific antigenicity of VP6 (reviewed in [8]). Groups A, D, F and G have been found in birds [1], with a predominance of RVA and RVD shedding [13]
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