Human Seasonal Influenza Viruses in Swine Workers in Lagos, Nigeria: Consequences for Animal and Public Health.

The influenza A virus has been scarcely investigated in pigs in Africa, with rare detection prior to 2009. The spread of A(H1N1)pdm09 changed the epidemiology due to frequent human-to-swine transmission and the emergence of various new reassortants. This study therefore aimed at estimating the level of circulation and characterizing influenza A viruses at the interface between swine workers, who are crucial players in the inter-species transmission of influenza A viruses, and their animals in several farms in Nigeria, a hub for pig production in Africa. This cross-sectional study showed that 24.6% (58/236) of the pig serum samples collected in 2013-2014 had anti-influenza A antibodies in the absence of vaccination programs, but none of the pig swabs (n = 1193) were positive according to RT-qPCR. Viral RNA was detected in 0.9% (2/229) of swine workers sampled at their place of work, and the strains were characterized as A(H1N1)pdm09 and seasonal A(H3N2). Our results highlight that more awareness of swine workers regarding the consequences of reverse zoonosis for animal and public health is warranted. Annual vaccination and the wearing of masks when experiencing influenza-like symptoms would help decrease influenza inter-species transmission, while surveillance should be adequately supported for early detection.

Hospital-based surveillance for Lassa fever in Edo State, Nigeria, 2005-2008.

OBJECTIVES: To estimate the burden of Lassa fever in northern and central Edo, a state in south Nigeria where Lassa fever has been reported. METHODS: Blood samples were obtained from 60 patients hospitalised at the Irrua Specialist Teaching Hospital (ISTH), Irrua, with a clinical suspicion of Lassa fever and from 451 febrile outpatients seen at the ISTH and hospitals in Ekpoma, Iruekpen, Uromi, Auchi and Igarra. All samples were tested retrospectively by Lassa virus-specific RT-PCR. Outpatients were additionally screened for Lassa virus-specific antibodies by indirect immunofluorescent antibody assay. RESULTS: Lassa virus was detected in 25 of 60 (42%) patients with a clinical suspicion of Lassa fever. The disease affected persons of all age groups and with various occupations, including healthcare workers. The clinical picture was dominated by gastrointestinal symptoms. The case fatality rate was 29%. Lassa virus was detected in 2 of 451 (0.44%) febrile outpatients, and 8 (1.8%) were positive for Lassa virus-specific IgG. CONCLUSIONS: Lassa fever contributes to hospital mortality in Edo State. The low prevalence of the disease among outpatients and the low seroprevalence may indicate that the population-level incidence is not high. Surveillance for Lassa fever should focus on the hospitalised patient.

Current molecular epidemiology of Lassa virus in Nigeria.

Recent Lassa virus strains from Nigeria were completely or partially sequenced. Phylogenetic analysis revealed the predominance of lineage II and III strains, the existence of a previously undescribed (sub)lineage in Nigeria, and the directional spread of virus in the southern part of the country. The Bayesian analysis also provided estimates for divergence times within the Lassa virus clade.

Measles virus strain diversity, Nigeria and Democratic Republic of the Congo.

We investigated the genetic diversity of measles virus (MV) in Nigeria (2004-2005) and the Democratic Republic of the Congo (DRC) (2002-2006). Genotype B3 strains circulating in Kinshasa, DRC, in 2002-2003 were fully replaced by genotype B2 in 2004 at the end of the second Congo war. In Nigeria (2004-2005), two genetic clusters of genotype B3, both of which were most closely related to 1 variant from 1998, were identified. Longitudinal analysis of MV strain diversity in Nigeria suggested that only a few of the previously described 1997-1998 variants had continued to circulate, but this finding was concomitant with a rapid restoration of genetic diversity, probably caused by low vaccination coverage and high birth rates. In contrast, the relatively low genetic diversity of MV in DRC and the genotype replacement in Kinshasa reflect a notable improvement in local measles control.

Molecular confirmation and phylogeny of Lassa fever virus in Benin Republic 2014-2016.

BACKGROUND: The changing epidemiology of the Lassa virus from endemic areas to other parts of West Africa has been reported. However, there have been no documented Lassa fever transmission chains in the Benin Republic. Two outbreaks of Lassa fever (November 2014 and January 2016) in the Benin Republic were characterised by a high number of deaths (more than 50%) among 27 confirmed and other unconfirmed cases. OBJECTIVES: We report the detection, confirmation and relatedness of the Lassa virus strains from the Benin Republic with other isolates within the West African Sub-region. METHODS: A total of 70 blood samples (16 from 2014 and 54 from 2016) from suspected cases with signs and symptoms suggestive of viral haemorrhagic fever were received for molecular analysis at the Centre for Human and Zoonotic Virology, College of Medicine, University of Lagos and the Lagos University Teaching Hospital. With the detection of the Lassa virus RNA by reverse transcriptase polymerase chain reaction, sequencing and phylogenetic analyses were performed using the Sanger dideoxy sequencing technology platform and the MEGA6 software. RESULTS: S segments of the Lassa virus RNA genome were detected in 5 (7.1%) of the 70 samples analysed. Sequencing and a phylogenetic tree construction confirmed that the strain of Lassa virus had close relationships with strains previously isolated from Nigeria. CONCLUSION: We confirmed the presence of the Lassa virus in the Benin Republic, with 2 strains having molecular epidemiological links with Lineage I and II strains from Nigeria. To reduce the likelihood of outbreaks, there is a need for heightened awareness and strengthened surveillance systems about Lassa fever, particularly in the sub-region.

Complete Genome Sequence of a Hepatitis E Virus Genotype 1e Strain from an Outbreak in Nigeria, 2017.

Hepatitis E virus genotype 1 (HEV-1) is associated with large epidemics. Notably, HEV subtype 1e (HEV-1e) has caused HEV outbreaks in sub-Saharan Africa. We report here the second full-length genome sequence of an HEV-1e strain (NG/17-0503) from a recent outbreak in Nigeria in 2017. It shares 94.2% identity with an HEV-1e strain from Chad.

Biosafety level-2 laboratory diagnosis of Zaire Ebola virus disease imported from Liberia to Nigeria.

INTRODUCTION: Global travel is an efficient route of transmission for highly infectious pathogens and increases the chances of such pathogens moving from high disease-endemic areas to new regions. We describe the rapid and safe identification of the first imported case of Ebola virus disease in a traveler to Lagos, Nigeria, using conventional reverse transcription polymerase chain reaction (RT-PCR) in a biosafety level (BSL)-2 facility. CASE PRESENTATION: On 20 July 2014, a traveler arrived from Liberia at Lagos International Airport and was admitted to a private hospital in Lagos, with clinical suspicion of Ebola virus disease. METHODOLOGY AND OUTCOME: Blood and urine specimens were collected, transported to the Virology Unit Laboratory at the College of Medicine, University of Lagos, and processed under stringent biosafety conditions for viral RNA extraction. RT-PCR was set-up to query the Ebola, Lassa and Dengue fever viruses. Amplicons for pan-filoviruses were detected as 300 bp bands on a 1.5% agarose gel image; there were no detectable bands for Lassa and Dengue viral RNA. Nucleotide BLAST and phylogenetic analysis of sequence data of the RNA-dependent RNA polymerase (L) gene confirmed the sequence to be Zaire ebolavirus (EBOV/Hsap/NGA/2014/LIB-NIG 01072014; Genbank: KM251803.1). CONCLUSION: Our BSL-2 facility in Lagos, Nigeria, was able to safely detect Ebola virus disease using molecular techniques, supporting the reliability of molecular detection of highly infectious viral pathogens under stringent safety guidelines in BSL-2 laboratories. This is a significant lesson for the many under-facilitated laboratories in resource-limited settings, as is predominantly found in sub-Saharan Africa.

Nomenclature- and database-compatible names for the two Ebola virus variants that emerged in Guinea and the Democratic Republic of the Congo in 2014.

In 2014, Ebola virus (EBOV) was identified as the etiological agent of a large and still expanding outbreak of Ebola virus disease (EVD) in West Africa and a much more confined EVD outbreak in Middle Africa. Epidemiological and evolutionary analyses confirmed that all cases of both outbreaks are connected to a single introduction each of EBOV into human populations and that both outbreaks are not directly connected. Coding-complete genomic sequence analyses of isolates revealed that the two outbreaks were caused by two novel EBOV variants, and initial clinical observations suggest that neither of them should be considered strains. Here we present consensus decisions on naming for both variants (West Africa: "Makona", Middle Africa: "Lomela") and provide database-compatible full, shortened, and abbreviated names that are in line with recently established filovirus sub-species nomenclatures.

Filovirus RefSeq entries: evaluation and selection of filovirus type variants, type sequences, and names.

Sequence determination of complete or coding-complete genomes of viruses is becoming common practice for supporting the work of epidemiologists, ecologists, virologists, and taxonomists. Sequencing duration and costs are rapidly decreasing, sequencing hardware is under modification for use by non-experts, and software is constantly being improved to simplify sequence data management and analysis. Thus, analysis of virus disease outbreaks on the molecular level is now feasible, including characterization of the evolution of individual virus populations in single patients over time. The increasing accumulation of sequencing data creates a management problem for the curators of commonly used sequence databases and an entry retrieval problem for end users. Therefore, utilizing the data to their fullest potential will require setting nomenclature and annotation standards for virus isolates and associated genomic sequences. The National Center for Biotechnology Information's (NCBI's) RefSeq is a non-redundant, curated database for reference (or type) nucleotide sequence records that supplies source data to numerous other databases. Building on recently proposed templates for filovirus variant naming [ ()////-], we report consensus decisions from a majority of past and currently active filovirus experts on the eight filovirus type variants and isolates to be represented in RefSeq, their final designations, and their associated sequences.

Phylogenetic analysis of the precore/core gene of hepatitis B virus genotypes E and A in West Africa: new subtypes, mixed infections and recombinations.

One hundred and twenty-two new hepatitis B virus (HBV) preC/C sequences and three complete genomes from three major countries in West Africa were analysed. The majority of sequences were of genotype E and the only other genotype found was genotype A. Although for genotype E sequences, the genetic diversity of the preC/C gene was about two to three times higher than that of the preS/S gene, it was still considerably lower than that for genotype A sequences. The HBV/E preC/C gene was related most closely to subgenotype D1 and D2 sequences. Evidence of recombination was found in two strains that were of genotype A in the preS/S gene and of genotype E in the preC/C gene. The genotype A strains from Cameroon, Mali and Nigeria could be divided phylogenetically into three subtypes, A3 and two new subtypes, tentatively designated A4 and A5. Each subtype presented a genetic diversity of 2.19-3.85 % and intersubtype distances of 4.47-5.97 %. Interestingly, one sample from Nigeria showed evidence of a triple recombination of genotypes E/D and A, separated by a genotype G-specific insert of 36 bp. Of 110 patients, 19 (17.3 %) showed a coinfection of genotypes A and E, mostly in human immunodeficiency virus-positive children from Cameroon. Thus, in Cameroon, where both genotypes coexist, 37 % of all individuals tested had mixed infections. The low genetic variability in the preC/C gene of genotype E supports our previous speculation about a relatively short evolutionary history of this genotype, in contrast to the subtype-rich African genotype A strains.

Low genetic diversity despite hyperendemicity of hepatitis B virus genotype E throughout West Africa.

Sub-Saharan Africa suffers from an excessively high endemicity of hepatitis B virus (HBV), but little is known about the prevalent genotypes. In this study, we investigated the PreS1/PreS2/S genes of 127 viruses obtained from 12 locations in Mali, Burkina Faso, Togo, Benin, Nigeria, Cameroon, and the Democratic Republic of Congo. Except for those obtained from the Cameroon HIV cohort (18/22 HBV genotype A), 96 of 105 sequences belonged to HBV genotype E (HBV/E), and viral DNA was very similar (1.67% diversity) throughout this vast HBV/E crescent, which spans 6000 km across Africa. The low diversity suggests that HBV/E may have a short evolutionary history. Considering a typical mutation rate of DNA viruses, it would take only 200 years for the strain diversity of HBV/E viruses to develop from a single introductory event. The relatively recent introduction of HBV/E into humans would also explain its conspicuous absence in the Americas, despite the forced immigration of slaves from west Africa, until the early 19th century. Infection during infancy is mostly associated with chronic carrier status, and this combination can account for the explosive spread of virtually identical viruses within a community, but whether other routes of long-range transmissions must be considered becomes an important question.