Towards a coordinated strategy for intercepting human disease emergence in Africa

Non peer reviewe

Epidemiology and molecular characterization of the re-emerging measles virus among children and adults in the Haut-Ogooue, Gabon

Abstract Background Measles is one of the most infectious diseases with a high mortality rate worldwide. It is caused by the measles virus (MeV) which is a single stranded RNA virus with genetic diversity based on the nucleoprotein gene, including 24 genotypes. In Gabon, several outbreaks occurred in the past few years, especially in 2016 in Libreville and Oyem. A surveillance network of infectious diseases highlighted a measles outbreak which occurred in the south of Gabon from April to June 2017. Methods Clinical specimens of urine, blood, throat and nasal swabs were collected in the two main cities of the Haut-Ogooue province, Franceville and Moanda. Virological investigations based on real-time polymerase chain reaction for molecular diagnosis and conventional PCR for genotype identification were done. Results Specimens were collected from 139 suspected measles patients. A total of 46 (33.1%) children and adults were laboratory-confirmed cases among which 16 (34.8%) were unvaccinated, 16 (34.8%) had received one dose, and 11 (23.9%) had received two doses of the measles vaccine. Phylogenetic analysis revealed that all the sequences of the nucleoprotein gene belonged to genotype B3. Conclusions Measles infection was more commonly confirmed among those with one recorded dose compared to suspect cases with none, unknown or two recorded doses. The molecular characterization of the strains showed the circulation of the B3 genotype which is endemic on the African continent, thirty years after the B2 genotype was described in an outbreak in Libreville, the capital of Gabon. These findings highlight that surveillance and molecular investigation of measles should be continued in Gabon

Results of real-time PCR on organs from <i>Coleura afra</i> individuals.

<p>Numbers indicate the cycle threshold (C<i>t</i>). ND, not done because of missing samples.</p><p>Undet, C<i>t</i> undetermined.</p><p>Results of real-time PCR on organs from <i>Coleura afra</i> individuals.</p

Overview of specimens collected in Belinga caves and tested by specific BelPV qPCR assay.

<p>Overview of specimens collected in Belinga caves and tested by specific BelPV qPCR assay.</p

Phylogenetic tree based on a 439-basepair fragment of the polymerase gene (L) of members of the <i>Paramyxoviridae</i> family.

<p>Sequences generated in this study are highlighted in red. Bayesian posterior probabilities are shown; values <0.80 were removed for clarity. The viruses are designated as follows (virus abbreviation/typical host/accession numbers of reference sequences in brackets): HeV  =  Hendra virus, NiV  =  Nipah virus, BatPV  =  Bat paramyxovirus, BeiPV  =  Beilong virus, JPV  = J virus, MosPV  =  Mossman virus, TupPV  =  Tupaia paramyxovirus, NarPV  =  Nariva virus, PDV  =  Phocine distemper virus, CDV  =  Canine distemper virus, CeMV DMV  =  Cetacean morbillivirus strain dolphin morbillivirus, MeV  =  Measles virus, PPRV  =  Peste-des-petits ruminants virus, RPV  =  Rinderpest virus, FdlPV  =  Fer-de-lance virus, PSPV  =  Pacific salmon paramyxovirus, ASPV  =  Atlantic salmon paramyxovirus, SeV  =  Sendai virus, bPIV3  =  Bovine parainfluenza virus 3, hPIV1  =  Human parainfluenza virus 1, hPIV3  =  Human parainfluenza virus 3, SwPIV3  =  Swine parainfluenza virus 3, NDV  =  Newcastle disease virus, PigeonPMV  =  Pigeon paramyxovirus, AMPV9  =  Avian paramyxovirus type 9, AMPV6  =  Avian paramyxovirus type 6, AMPV2  =  Avian paramyxovirus type 2, AMPV3  =  Avian paramyxovirus type 3, AMPV4  =  Avian paramyxovirus type 4, PIV5  =  parainfluenza virus 5, SV41  =  Simian virus 41, MenPV  =  Menangle paramyxovirus, MprPV  =  Mapuera virus, MuV  =  Mumpsvirus, PorPV  =  Porcine rubulavirus, TioPV  =  Tioman paramyxovirus, hPIV2  =  Human parainfluenza virus 2, hMPV  =  Human metapneumovirus, MPV  =  Murine pneumonia virus, bRSV  =  Bovine respiratory syncytial virus, hRSV  =  Human respiratory syncytial virus, APV  =  Avian Pneumovirus, ThkPV-1  =  Tuhoko virus 1, ThkPV-2  =  Tuhoko virus 2, ThkPV-3  =  Tuhoko virus 3.</p

Virus distribution in organs from <i>Coleura afra</i> individuals.

<p>Virus distribution is shown in terms of C<i>t</i> values on the y-axis for each bat organ tested (x-axis). <i>n</i> represents the number of organs available for the study.</p