H7N6 highly pathogenic avian influenza in Mozambique, 2023.

On 13 October 2023, the National Directorate for Livestock Development in Mozambique was notified of a suspected outbreak of avian influenza in commercial layers. Samples were screened by real-time and conventional RT-PCR and were positive for both H7 and N6. Full genome sequences were obtained for three representative samples. Sequence analysis of the H7 cleavage site confirmed that the viruses were highly pathogenic (i.e. 333- PEPPKGPRFRR/GLF-346). In addition, the H7 and N6 sequences were highly similar (from 99.4-99.5% and 99.6-99.7% for the HA gene and the NA gene, respectively) to the sequences of a H7N6 virus identified in the Republic of South Africa in May 2023 indicating a similar origin of the viruses. The identification of H7N6 HPAIV in Mozambique has important implications for disease management and food security in the region.

Development of a quadrivalent foot-and-mouth disease vaccine candidate for use in East Africa.

Foot-and-mouth disease (FMD) is a highly contagious viral disease of livestock which is prevalent across Africa, the Middle East, Asia, and South America where it has a severe economic impact on the agriculture industry. Vaccination with inactivated viral vaccines is used as the main control measure in these endemic regions of the world, however the presence of multiple serotypes, subtypes, and the continual emergence of new, antigenically divergent strains limits its effectiveness. East Africa (EA) has been identified as a region that would particularly benefit from updated FMD vaccines, since those currently in use contain older strains which do not provide good protection against contemporary strains. Four serotypes are currently circulating in EA, necessitating the development of a quadrivalent vaccine containing representative strains of each serotype. A key consideration in the selection of vaccine strains is the stability of the virus particle, since the capsids readily dissociate on exposure to elevated temperatures, but only intact capsids induce protective immunity to FMD. Therefore, with a view to producing a more stable, updated quadrivalent vaccine for EA, we recently screened a panel of foot-and-mouth disease virus (FMDV) isolates from the region to select strains with naturally higher thermostabilities and confirmed their immunogenicity in cattle. Herein we describe the formulation and serological assessment of wild-type and recombinant quadrivalent vaccine candidates comprising these stable strains, and demonstrate that both vaccines generate high neutralising antibody titres against the homologous strains and also to heterologous strains from EA. Importantly, the vaccine passed the criteria set by the AgResults vaccine challenge project and offers good cross-protection against a panel of regional FMDV strains.

A survey of contagious ecthyma and molecular characterization of Orf virus in sheep and goats in Nigeria (2014-2016).

Background: Outbreaks of contagious ecthyma (CE) are frequently reported in sheep and goat flocks in Nigeria with severe clinical outcomes. CE is a debilitating and economically important disease primarily affecting sheep and goats caused by the Orf virus (ORFV). Despite field reports of CE in the country, there is no concise country-wide epidemiological data on the disease and limited genetic data of circulating Nigerian ORFV are available in the public domain. Aim: An epidemiological survey of CE and molecular characterization of ORFV circulating in Nigeria from 2014 to 2016. Method: Data were collected using designed questionnaires, administered to veterinarians and farmers in selected States of Nigeria. Samples were collected during passive surveillance for CE from 2014 to 2016 which were analyzed by polymerase chain reaction (PCR). The A32L and B2L genes of circulating ORFV were also characterized. Results: Analysis of the questionnaire showed that 69.54% (n = 82/118) of the farmers claimed to have experienced CE in their flocks with average morbidity and mortality rates of 25% and 15%, respectively. A total of 113 veterinarians participated in the study, with 69.9% (n = 79) familiar with CE and claimed CE causes morbidity rates of 25%-37% and mortality rates of 10%-15% in sheep and goats. Laboratory results revealed that ORFV was detected in 72% (18/25) of outbreak samples analyzed by real-time PCR. Phylogenetic analysis of A32L and B2L genes revealed that Nigerian ORFV sequences belong to clusters I and II and are similar to viruses from India, Ethiopia, and China. Conclusions: This study is the first nationwide epidemiological data on the status of CE in sheep and goats in Nigeria. It is also the first report of molecular characterization of two genes of ORFV circulating and causing outbreaks in small ruminants in the country. This study showed that CE is under-reported, widespread and of economic importance to sheep and goat farmers in Nigeria.

Molecular epidemiology of peste des petits ruminants virus in Nigeria: An update.

Peste des petits ruminants (PPR) is a highly contagious viral disease that mainly affects goats and sheep in Asia, Africa and the Middle East. The PPR virus (PPRV) can be classified into four genetically distinct lineages (I, II, III and IV). All have been historically present in Africa, except the Asian lineage IV that has been spreading across the globe and across Africa in recent decades. Previous studies have identified the presence of lineage IV in Nigeria since 2010. In the present study, samples were taken from 429 small ruminants with PPR symptoms across Nigeria in 2017-2020 to provide an update on the distribution and genetic diversity of PPRV in the country. Sequences from a portion of the PPRV nucleoprotein (N) gene were obtained from 91 samples, 90 belonging to lineage IV and one to lineage II. Phylogenetic analysis identified at least four lineage IV sub-clusters in Nigeria, grouping samples across multiple regions. Our results suggest extensive endemic circulation of a wide range of PPRV strains across Nigeria and across borders with neighbouring countries, underlining the difficulty involved in controlling the disease in the region.

Wide circulation of peste des petits ruminants virus in sheep and goats across Nigeria.

Peste des petits ruminants (PPR) is a highly contagious viral disease that mainly affects goats and sheep in Asia, Africa and the Middle East, and threatens Europe [R.E.1]. The disease is endemic on the African continent, particularly in West Africa, and is a major factor driving food insecurity in low-income populations. The aim of this research study was to carry out surveillance, genetic characterisation and isolation of recently circulating PPR viruses (PPRV) in sheep and goats from the six agro-ecological zones of Nigeria. A total of 268 post-mortem tissue samples of lung and mesenteric ganglia were collected from clinically suspected sheep and goats in 18 different states, of which five never previously sampled. The presence of PPRV was confirmed using a reverse-transcription coupled with a polymerase chain reaction (RT-PCR) assay. A total of 72 samples, 17 sheep (6%) and 55 goats (21%), were found to be PPR positive. Positive samples were distributed in almost all states, except Kano, where PPR was detected in previous studies. The PPRV-positive samples were further confirmed by sequencing or virus isolation in areas where the infection had never previously been detected. These results confirm the active circulation of PPRV across all six agro-ecological zones of Nigeria, and consequently, the need for introducing strict measures for the control and prevention of the disease in the country.

Co-infection of peste des petits ruminants and goatpox in a mixed flock of sheep and goats in Kanam, North Central Nigeria.

Peste-des-petits-ruminants (PPR) and Goat pox (GTP) are two devastating and economically important transboundary animal diseases of small ruminants in Africa and Asia that have been difficult to control. This study however, investigated an outbreak of PPR and GTP in a mixed flock of indigenous sheep and goats in Kanam, North Central Nigeria. A total of nine sera and seven tissues (lungs, spleen, scab and skin) samples were collected and analysed in the laboratory using competitive enzyme linked immunosorbent assay (cELISA) for PPR antibodies and polymerase chain reaction (PCR) for detection of PPR virus (PPRV) and GTP virus (GTPV). Gene fragments of the nucleoprotein of PPRV and the G-protein-coupled chemokine receptor (GPCR) of GTPV were amplified and sequenced to confirm the presence of the causative viruses. Serologically, antibodies to PPRV were detected in all (9/9) sera collected. GTPV and PPRV was detected in corresponding samples (42.8% n = 3/7) of the scab/skin samples collected by both PCR and RT-PCR technique. The phylogenetic analysis of PPRV revealed that the virus belongs to lineage IV and clustered with viruses from Gabon and Cameroon. Similarly, the GTPV also clustered with other sequences from Burkina Faso and Yemen. The positive cELISA, RT-PCR and PCR results from samples collected from the same animals confirmed co-infection of PPR and GTP in this mixed flock of sheep and goats. This is the first report of concurrent infection of PPR and GTP in mixed flock of sheep and goats in Nigeria. Our findings underscore the need for farmers to vaccinate their flock to control spread and economic losses as result of these diseases.

DIAGNOSIS OF ORF IN WEST AFRICAN DWARF GOATS IN UYO, AKWA IBOM STATE, NIGERIA.

BACKGROUND: Sixty (60) male West African Dwarf goats were reported with clinical signs of enlarged lymph nodes, scabs on the mouth, nose and ears. Two of the goats died and post mortem examination reveals enlarged submandibular lymph nodes and vesicular lesions on the tongue. Clinical diagnosis of Orf has been reported in Nigeria but this report is the confirmatory diagnosis of Orf in a suspected outbreak in an experimental farm in Uyo, Akwa Ibom State, Nigeria using molecular techniques. MATERIALS AND METHODS: Scabs, spleen and lymph node samples from goats suspected to have died from Orf were collected, transported on ice to the laboratory and homogenized. The DNA was extracted using QIAmp DNA minikit (Qiagen) according to the manufacturer's instructions. Orf virus (ORFV) was amplified using published ORFVspecific primers by PCR. RESULTS: Morbidity and mortality were 100% and 3.3% respectively, while ORFV was detected by PCR. Diagnosis of Orf was confirmed based on clinical signs of enlarged lymph nodes, scabs on the mouth, nose and ears, necropsy findings of enlarged submandibular lymph nodes and vesicular lesions on the tongue and PCR results. CONCLUSION: This may be the first report of molecular diagnosis of Orf in Nigeria. The 100% morbidity and 3.3% mortality rate is higher than previously reported thus Orf is becoming of greater economic importance than previously thought. It is therefore recommended that routine laboratory diagnosis of Orf be carried nationwide to determine the prevalence of Orf in Nigeria.

Sero-Surveillance of Lyssavirus Specific Antibodies in Nigerian Fruit Bats (Eidolon helvum).

The aetiological agent of rabies is a member of the Lyssavirus genus (Rhabdoviridae family, order Mononegavirales). The disease (rabies) is endemic in many parts of Asia and Africa and still remains an important public and veterinary health threat. In Nigeria, there is a dearth of information on the natural infection and/or exposure of bat species to lyssaviruses. Therefore, this study was undertaken to assess the prevalence of rabies virus (RABV) neutralizing antibodies in sera obtained from bats from the central Plateau and North-East Bauchi States in Nigeria. Two hundred serum samples were collected from Nigerian fruit bats from six different locations and tested for anti-RABV antibodies using a commercial blocking ELISA. Of the 200 bat serum samples collected, one batch consisting of 111 samples did not meet the validation criteria and hence was not included in the final analysis. Of the remaining 89, only three (3.4%) contained anti-lyssavirus antibodies, demonstrating a low prevalence of lyssavirus antibodies in the study population. In order to further understand the exposure of bat species to phylogroup II lyssaviruses (Lagos bat virus and Mokola virus), the same panel of samples will be tested for neutralizing antibodies to phylogroup II members, viruses that do not cross-neutralize with members of phylogroup I.

Serosurvey of peste des petits ruminants virus in small ruminants from different agro-ecological zones of Nigeria.

Peste des petits ruminants, caused by the peste des petits ruminants virus (PPRV), is a highly contagious and economically important transboundary viral disease of domestic and wild small ruminants and a major hindrance to small-ruminant production in Nigeria. The seroprevalence and distribution of PPRV antibodies in small ruminants in rural households, farms, live animal markets and slaughter slabs across the six different agro-ecological zones of Nigeria were determined. A total of 4548 serum samples from 3489 goats and 1059 sheep were collected in 12 states. A PPRV competitive enzyme-linked immunosorbent assay was used to test the samples and the data analysed with R statistical software version 3.0.1. The study animals included all ages and both sexes. The overall prevalence estimate of sera positive for PPRV antibodies was 23.16% (n = 1018 positive samples per 4548 total samples, 95% confidence interval: 21.79% - 24.57%). There were significant differences in the seroprevalence between the states (p = 0.001). Taraba State had the highest seroprevalence of 29.51%, whilst the lowest seroprevalence of 14.52% was observed in Cross River State. There were no significant differences in the PPRV seroprevalence between male and female animals (p = 0.571), age (p = 0.323) and between species (p = 0.639). These data indicate the current seroprevalence to PPRV in the small-ruminant population in Nigeria.

Serological evidence of camel exposure to peste des petits ruminants virus (PPRV) in Nigeria.

Peste des petits ruminants (PPR), a viral disease of sheep and goats, is endemic in Nigeria. There are reports indicating the involvement of peste des petits ruminants virus (PPRV), the causative agent of PPR, in a camel respiratory syndrome in Africa. Considering that camels share the same grazing land and drinking points with other ruminants, this study was undertaken to determine the seroprevalence and extent of PPRV antibodies in Nigerian camels. A total of 1517 camel sera samples were collected from four states (Borno, Kano, Kastina and Sokoto). The seroprevalence was determined by the H-protein-based competitive ELISA. The overall prevalence was 3.36% (51/1517, 95% confidence interval of 2.51-4.39%). There was no significant differences in prevalence between states (p = 0.8921) and between male and female camels (p = 0.7424). The prevalence differed significantly (p < 0.00001) by body condition score; camels with poor body condition score has higher (16.67%) antibody seroprevalence to PPR compared to those with fair and good body condition score. There was a statistically significant difference between camels aged ≤ 5 years and those >5 years (p = 0.0042). These results show occasional transient PPRV infection of camels in Nigeria, and there is the need to include camels among species to be studied in elucidating the epidemiology of the disease in sheep and goats.

WITHDRAWN: Identification of peste-des-petits ruminants virus (PPRV) lineage IV, the Asian lineage, in Nigeria and co-circulation with PPRV lineage II.

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Phylogenetic analysis of the haemagglutinin gene of current wild-type canine distemper viruses from South Africa: lineage Africa.

There are no reports of CDV isolations in southern Africa, and although CDV is said to have geographically distinct lineages, molecular information of African strains has not yet been documented. Viruses isolated in cell cultures were subjected to reverse transcription-polymerase chain reaction (RT-PCR), and the complete H gene was sequenced and phylogenetically analysed with other strains from GenBank. Phylogenetic comparisons of the complete H gene of CDV isolates from different parts of the world (available in GenBank) with wild-type South African isolates revealed nine clades. All South African isolates form a separate African clade of their own and thus are clearly separated from the American, European, Asian, Arctic and vaccine virus clades. It is likely that only the 'African lineage' of CDV may be circulating in South Africa currently, and the viruses isolated from dogs vaccinated against CDV are not the result of reversion to virulence of vaccine strains, but infection with wild-type strains.