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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-017-0778-5) contains supplementary material, which is available to authorized users.
Levamisole hydrochloride (Lev.HCl) has been acclaimed to boost immune response particularly in immunocompromised state. Its routine use as an immunomodulator in poultry production is yet to be well embraced, thus its effects of on cellular immunity and flock performance of commercial broilers were evaluated.One hundred and fifty Anak broiler chicks were separated into two groups of 75 each. Broilers in group 1 were sensitized with 150µg of Staphylococcus aureus antigen each at 4 and 5 weeks, while those in group 2 were not sensitized. Each group was further divided into subgroups A, B, and C. Levamisole hydrochloride (40 mg/kg) was administered orally to 1A and 2A at 45 and 46 days of age and to 1B and 2B at 47 and 48 days of age, while 1C and 2C were not treated. At 47 days of age, 12 broilers from all subgroups were challenged with 75µg of S. aureus antigen each at the right wattle. Wattle thickness was measured till 72 hours post challenge (pc) and delayed wattle reaction (DWR) was determined. Tissues were harvested at 72 hours pc for histopathology. Morbidity, mortality and live weights at 8 weeks of age were recorded. DWR peaked at 4 hours pc in 1A (2.22 ± 0.21 mm) and 1B (2.96 ± 0.21 mm) and 24 hours pc in 1C (3.39 ± 0.34 mm), the difference being significant (p<0.05). Inflammatory lesions were observed in wattles of sensitized subgroups and were more severe in 1C. Mortality rates were 4.17% and 29.17% in 1A and 1C respectively. Mean live weights in A and B i.e. 1.57± 0.06 kg and 1.56 ± 0.06 kg respectively, were significantly higher (p<0.0) than 1.43 ± 0.08 kg in C. Levamisole enhanced DTH via an early response, improved broiler liveability, and its anti-inflammatory property was confirmed.
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