Seroprevalence of Influenza A Virus in Dromedaries in North-Western Nigeria.

Although influenza A virus is endemic in wild waterfowl, domestic poultry, swine, humans, bats, cetaceans, dogs, and horses, there is a paucity of data on the potential role of camels in zoonotic transmission of the virus. To estimate the seroprevalence of the influenza A virus in camel populations, four local government areas of Nigeria that share an international border with the Niger Republic were selected. Blood samples from 184 one-hump camels (dromedaries) were collected and tested for influenza IgG antigen by ELISA. Each camel's demographic variable, such as age, gender, location, production system, and usage, was recorded. The overall seroprevalence rate of influenza virus IgG in this study was 10.33% (95%CI: 6.33-15.66%). In the bivariate model, there was no significant difference in gender, age, site location and production system, except for usage. There was a significantly lower seroprevalence rate among camels used for labour (odds ratio (OR) = 0.34, 95% CI: 0.10-0.97) than those used for meat consumption; however, not after adjusting for other variables in the model. Increase surveillance through early detection, prediction, and risk assessment of pathogens in animal reservoirs and environmental contamination as One Health strategies to reduce potential human spillover is recommended. Molecular epidemiology studies could better elucidate the role of camels in the dynamics of disease transmission pathways.

Seroprevalence of Equine Influenza and Its Associated Risk Factors in Northwest Nigeria.

Equine influenza (EI) is a fast-spreading respiratory disease of equids caused by equine influenza A virus (EIV), often resulting in high morbidity and a huge economic impact on the equine industry globally. In this cross-sectional study to determine the seroprevalence of EI and its associated risk factors, sera from 830 horses bled on a single occasion in Northwest Nigeria between October 2019 and January 2020 were screened for antibodies to A/equine/Richmond/1/2007 (H3N8) using the single radial haemolysis (SRH) assay. Antibodies were detected in 71.3% (592/830, 95% CI: 68−74%) of horses (SRH area ≥ 0.5 mm2). Although there were statistically significant univariable associations between seropositivity and age, sex, breed, purpose and coat colour, only age remained significant when included with each of the other variables in bivariable analyses. There was a clear trend for increasing odds of seropositivity with increasing age: OR 1.6, 95% CI: 1.05−2.40 (p = 0.03) for 5−14-year-olds and OR 8.13, 95% CI: 2.75−24.1 (p < 0.001) for ≥15-year-olds compared to horses <5 years old. The mean SRH value was 78.2 mm2 (median = 88 mm2, interquartile range = 0−121 mm2) with only 9% of the horses having an SRH value > 150 mm2, considered sufficient to protect against clinical disease and virus shedding. Comparative screening of a subset of the horses (n = 118) with a 2019 H3N8 virus (A/equine/Worcestershire/2019) revealed a significantly greater seropositivity (p = 0.0001) than A/equine/Richmond/1/2007 consistent with exposure of the population during a widespread outbreak of EI in the region in 2019. In conclusion, there was an insufficient level of protection against EI in the region and introduction of a vaccination programme with vaccines containing recently circulating virus is recommended to mitigate against further outbreaks of EI in Nigeria.

Molecular characterization of dermatophytes isolated from cattle in Plateau State, Nigeria.

Dermatophytes from cattle were successfully characterized to species and strain levels for the first time in Nigeria. This study was undertaken to isolate and characterize dermatophytes from cattle in Plateau State, Nigeria. Two molecular techniques were utilized. The first was the use of polymerase chain reaction (PCR) to amplify the internal transcribed spacer regions of the ribosomal DNA using ITS-1 and ITS-4 as primers. This was followed by restriction fragment length polymorphism analysis of the amplified ITS regions using the enzyme MvaI to identify dermatophyte species. The second technique was a PCR using the short oligonucleotide 5'-GACAGACAGACAGACA-3' as primer for the RAPD typing of the isolates for identification of dermatophytes based on species specific profiles. Profiles of dermatophytes and their correlation with location, site of infection and severity of disease were also investigated. Both PCR-RFLP and RAPD analysis identified 26 Trichophyton verrucosum and 22 Trichophyton mentagrophytes. The PCR-RFLP analysis of the ITS regions produced two distinct profiles for both T. mentagrophytes and T. verrucosum. The first Profile for T. mentagrophytes consisted of two fragments of approximately 320 bp and 280 bp in length while the second was approximately 350 bp and 250 bp in length. The first profile for T. verrucosum consisted of two fragments having bands of approximately 380 bp and 220 bp. The second profile had a single band of undigested fragment of approximately 600 bp in length. Both T. mentagrophytes and T. verrucosum yielded identifiable fragments by RAPD analysis. Six profiles were produced for T. mentagrophytes and the PCR finger prints ranged from 1 to 9 bands with sizes ranging from approximately 350 to 5000 base pairs in size. Amplification of T. verrucosum isolates produced four Profiles. The PCR fingerprints ranged from 5 to 7 bands with sizes ranging from 500 bp-5000 bp. The results indicate that differences in location could contribute to variations in PCR amplicons of dermatophytes and strain differences in dermatophytes may be responsible for variation in clinical dermatophytosis but no significant association was observed between profiles of dermatophytes and the site of infection. The PCR-RFLP analysis of the internal transcribed spacer regions using the primer set ITS1/ITS4 and RAPD analysis using (GACA)4 as primer were successfully used to accurately identify dermatophytes from cattle to species and strain levels. Few molecular studies targeting dermatophytes of cattle are available in the literature. As far as we know, this may be the first report of molecular characterization of cattle dermatophytes from Africa.

Molecular Detection of Torque Teno Sus Virus and Coinfection with African Swine Fever Virus in Blood Samples of Pigs from Some Slaughterhouses in Nigeria.

Torque teno sus virus 1 (TTSuV1a/TTSuV1b) infection is present in pig herds worldwide. This study investigated the prevalence of TTSuV1a/TTSuV1b infections in domestic pigs from some slaughterhouses in Nigeria as well as coinfection with African swine fever virus (ASFV) and described the phylogeny in relation to global strains. One hundred and eighty-one (181) blood samples from four slaughterhouses were used for the study and viral nucleic acid detection was carried out by PCR. Comparative sequence analysis was carried out to infer phylogeny. The overall prevalence of TTSuV1a/b was 17.7%. Prevalence of individual genotypes was 10.5% and 7.2% for TTSuV1a and TTSuV1b, respectively. Coinfection of ASFV/TTSuV1a/b was 7.7% while that of TTSuV1a and TTSuV1b was 1.7%. ASFV alone was detected in 11.91% of the total samples. The Nigerian TTSuV1a and TTSuV1b shared a sequence identity of 91-100% and 95-100%, respectively, among each other. The ASFV sequences were 100% identical to members of genotype 1. This is the first report on the presence of TTSuV1a/b in domestic pigs in Nigeria and coinfection with ASFV. Although the prevalence of TTSuV1a/b in Nigeria was low, we recommend further studies to establish the trend and possible role in the pathogenesis of ASFV.

First report of hepatitis E virus circulation in domestic pigs in Nigeria.

Hepatitis E virus (HEV) is an important cause of acute hepatitis in humans. Zoonotic transmission between pigs and humans has been confirmed. Human HEV infection is common in Nigeria; however, characterization of HEV infection in other species was lacking. The objective of this study was to investigate HEV infection in Nigerian pigs. A total of 286 serum samples from six states in Nigeria were tested for presence of anti-HEV IgG. Ninety fecal samples from one of these states (Plateau State) were tested for presence of HEV RNA. The overall prevalence of anti-HEV IgG-positive or suspect-positive pigs was 55.6% (159 of 286) with regional prevalence rates ranging from 36% (9 of 25; Delta State) to 88% (22 of 25; Taraba State). The overall HEV RNA prevalence rate was 76.7% (69 of 90). All polymerase chain reaction-positive samples belonged to HEV genotype 3 based on sequencing. The results indicate that HEV genotype 3 infection is widespread in Nigerian pigs.

Development of a fluorescent microbead-based immunoassay for the detection of hepatitis E virus IgG antibodies in pigs and comparison to an enzyme-linked immunoassay.

Swine hepatitis E virus (HEV) is a zoonotic virus and pigs are considered as an important reservoir. Swine HEV infection is widespread and most pig herds are infected. Humans can be infected with swine HEV via consumption of undercooked pork or through direct contact with infected pigs. To minimize the risk of zoonotic transmission, sensitive tools to assess the HEV infection status of pigs and pork products are needed. The objective of this study was to develop a fluorescent microbead-based immunoassay (FMIA) for the detection of IgG antibodies against swine HEV and compare it to an in-house enzyme-linked immunoassay (ELISA). Three sets of samples were utilized: (A) samples from pigs infected experimentally with different strains of HEV (positive controls, n=72), (B) samples from known HEV-negative pigs (negative controls, n=62) and (C) samples from pigs of unknown HEV infection status (n=182). All samples were tested by both ELISA and FMIA. The results on the experimental samples with known HEV exposure indicate that both assays have a specificity of 100% while the sensitivity ranges from 84.6% (ELISA) to 92.3% (FMIA). The overall prevalence of HEV IgG antibodies in field samples from pigs with unknown HEV exposure was 21.9% (40/182) for the ELISA and 21.4% (39/182) for the FMIA. The two assays had an almost perfect overall agreement (Kappa=0.92).

Spatio-temporal epidemiology of highly pathogenic avian influenza (H5N1) outbreaks in Nigeria, 2006-2008.

From 2006 to 2008, outbreaks of highly pathogenic avian influenza A (HPAI) virus of the H5N1 subtype occurred among poultry in Nigeria. We described the spatio-temporal patterns of the HPAI H5N1 outbreaks in Nigeria. Data of suspected and laboratory confirmed outbreaks maintained at the National Veterinary Research Institute Vom was analyzed using descriptive and exploratory analyses, GIS mapping, global and local spatial statistical analyses using the Cuzick-Edwards' (C-E) test and SaTScan Space-Time Scan Statistic. A total of 1654 suspected outbreaks were reported from 32 of the 36 States and the Federal Capital Territory (FCT), 299 were confirmed HPAI H5N1 positive from 27 states and FCT. The outbreaks occurred as three distinct epidemic waves with peak periods of January-March mainly in the North-West, North-Central and North-East regions during 2006 and 2007 and July-September in the South-West and South-South regions in 2007. Three spatio-temporal clusters were identified extending across States and international borders, consistent with disease transmission occurring through local and long-distance spread. This calls for enhanced strategies by the states and regional authorities to improve surveillance, prevention and control measures at the states, national and international levels.

Molecular characterisation of African swine fever viruses from Nigeria (2003-2006) recovers multiple virus variants and reaffirms CVR epidemiological utility.

Samples collected from wild and domestic suids in Nigeria, over a 3-year period (2003-2006), were evaluated for African swine fever (ASF) virus genome presence by targeting three discrete genome regions, namely the 478-bp C-terminal p72 gene region advocated for genotype assignment, a 780-bp region spanning the 5'-ends of the pB125R and pB646L (p72) genes and the hypervariable central variable region (CVR) encoded within the 9RL ORF (pB602L). ASF virus (ASFV) presence was confirmed in 23 of the 26 wild and domestic pigs evaluated. No evidence of ASF infection was found in two warthogs from Adamawa State; however, one bushpig from Plateau State was positive. Nucleotide sequences of the 478-bp and 780-bp amplicons were identical across all ASFV-positive samples sequenced. However, five discrete CVR variants were recovered, bringing the total number identified to date, from Nigeria, to six. The largest of the CVR variants, termed 'Tet-36' was identical to a virus causing outbreaks in neighbouring Benin in 1997, indicating a prolonged persistence of this virus type in Nigeria. Co-circulation of three tetramer types (Tet-36, Tet-27 and Tet-20) was found in Plateau State in July 2004, whilst in Benue State, two tetramer types (Tet-20 and Tet-21) were present in August 2005. Despite simultaneous field presence, individual co-infection was not observed. This study has reaffirmed the epidemiological utility of the CVR genome region for distinguishing between geographically and temporally constrained genotype I viruses, and has revealed the presence of multiple ASFV variants in Nigeria.