Importation and outbreak of wild polioviruses from 2000 to 2014 and interruption of transmission in Cameroon

Detection and genetic diversity of parechoviruses in children with acute flaccid paralysis in Cameroon

Human Parechoviruses (HPeVs) have rarely been considered in the virological investigation of Acute Flacid Paralysis (AFP) cases in Africa, where enteric infections are very common. This study investigated the prevalence and genetic diversity of HPeV in 200 children aged ≤ 15 years with AFP in Cameroon from 2018 to 2019. HPeVs were detected in their faecal RNA using 5'-untranslated real-time RT-PCR. Detected HPeVs were typed by phylogenetic comparison with homologous sequences from homotypic reference strains. Overall, HPeV RNA was detected in 11.0% (22/200) of the 200 stool samples tested. Twelve HPeVs were successfully sequenced and reliably assigned to HPeV-A1, A4, A5, A10, A14, A15, A17 and A18 genotypes. Phylogenetic analyses revealed a high genetic variability among the studied HPeVs, as well as between the studied HPeVs and their previously reported counterparts from Cameroon in 2014. These findings suggest that different HPeV genotypes co-circulate in Cameroon without documented epidemics.

Detection and characterization of polioviruses originating from urban sewage in Yaounde and Douala, Cameroon 2016-2017

Objective

Transmission of wild polioviruses (WPVs) and vaccine-derived polioviruses (VDPVs) have been interrupted in Cameroon since July 2014. Subsequently, Cameroon withdrew Sabin type 2 from routine immunization in April 2016. This study aimed to investigate the detection rates and overtime distribution of the types of PVs recovered from urban sewage in Cameroon.

Results

From January 2016 to December 2017, 517 sewage specimens originating from Yaounde (325 specimens) and Douala (192 specimens) were analyzed. No WPVs and VDPVs were isolated in this study. In contrast, vaccine strains of poliovirus were detected throughout the study period. Isolates Sabin types 1 and 3 were sporadically detected whereas Sabin 2 was found only from January to May 2016 both in Yaounde and Douala. The absence of Sabin 2 in sewage specimens since June 2016 indicates its rapid disappearance after withdrawal from routine immunization in April 2016. This study provides substantial support to the observation that WPV and VDPVs have been successfully eliminated in Cameroon. However, it remains essential to maintain and extend high quality environmental surveillance as long as WPV reservoirs and VDPV outbreaks are detected in Africa.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4280-6) contains supplementary material, which is available to authorized users.

Prevalence of poliovirus vaccine strains in randomized stool samples from 2010 to 2018: encompassing transition from the trivalent to bivalent oral poliovirus vaccine

Global eradication of poliovirus (PV) has previously relied on the live attenuated oral poliovirus vaccine (OPV). However, in order to eliminate the risk of vaccine-associated paralytic poliomyelitis, the use of OPV will soon be discontinued. Thailand has introduced inactivated polio vaccine since December 2015 and replaced trivalent with bivalent OPV since April 2016. To provide crucial surveillance data during this polio vaccine transition period, poliovirus shedding in stool was performed. A total of 7446 stool samples between 2010 and September 2018 were tested for poliovirus using reverse-transcription polymerase chain reaction. Approximately 0.44% (33/7446) of the samples tested were positive for PV. All positive specimens had more than 99% homology with the Sabin vaccine strain, based on complete VP1 nucleotide sequences. Although trivalent OPV use has been discontinued in Thailand since April 2016, PV type 2 could be detected in stool samples collected in May 2016 but has not been found afterwards. The use of bivalent OPV was able to reduce PV type 2 shedding in stools and could contribute to the reduction of vaccine-associated paralytic poliomyelitis in Thai children.

Successful polio supplementary immunisation activities in a security compromised zone - Experiences from the Southwest region of Cameroon

BACKGROUND

Supplementary immunisation activities (SIAs) play a central role in polio eradication efforts. Armed conflicts resulting in insecurity negatively affect SIAs. In the Southwest region of Cameroon, armed conflicts persisted in 2018. We present our experiences of conducting a polio SIA in an insecure region.

METHODS

The SIA took place from the 2nd to 4th of March 2018 and targeted 307,920 children aged 0-59 months. Bivalent polio vaccine was used. Before the SIA, extensive planning was done under the leadership of a Central Technical Group. Planning included security assessment, advocacy and social mobilisation.

RESULTS

Only 4 of the 18 health districts (HDs) of the Southwest region were considered safe. Regardless, vaccination teams worked in all HDs. The SIA achieved a coverage of 89.9%. Town criers and social mobilisers were the main sources of information about the SIA. Most (76%) children were vaccinated using the door to door strategy. There was no case of vaccine refusal.

CONCLUSION

Community members were very receptive of the SIA and this may be due to the communication that was adopted. Strong dedication by vaccination teams, community members' understanding and acceptance of polio SIAs are all key factors to the eradication of polio in conflict zones.

Mapping for Health in Cameroon: Polio Legacy and Beyond

During the poliovirus outbreak in Cameroon from October 2013 to April 2015, the Ministry of Public Health’s Expanded Program on Immunization requested technical support to improve mapping of health district boundaries and health facility locations for more effective planning and analysis of polio program data. In December 2015, teams collected data on settlements, health facilities, and other features using smartphones. These data, combined with high-resolution satellite imagery, were used to create new health area and health district boundaries, providing the most accurate health sector administrative boundaries to date for Cameroon. The new maps are useful to and used by the polio program as well as other public health programs within Cameroon such as the District Health Information System and the Emergency Operations Center, demonstrating the value of the Global Polio Eradication Initiative’s legacy.

Spatio-temporal spread of infectious pathogens of humans

Spatio-temporal aspects in the propagation of infectious pathogens of humans are reviewed. Mathematical modelling of these issues using metapopulation models is presented.