The African Vaccine-Preventable Diseases Network: a vaccine advocacy initiative.

Achieving high and equitable childhood immunisation coverage in Africa will not only protect children from disability and premature death, it will also boost productivity, reduce poverty and support the economic growth of the continent. Thus, Africa needs innovative and sustainable vaccine advocacy initiatives. One such initiative is the African Vaccine-Preventable Diseases Network, formed in 2009. This association of immunisation practitioners, vaccinologists, paediatricians, and infectious disease experts provides a platform to advocate for the introduction of newly available vaccines (e.g. 10-valent and 13-valent pneumococcal conjugate and rotavirus vaccines) into the Expanded Programme on Immunisation (EPI) as well as increased and equitable coverage for established EPI vaccines.

Whole-genome analysis reveals the complex evolutionary dynamics of Kenyan G2P[4] human rotavirus strains.

Although G2P[4] rotaviruses are common causes of acute childhood diarrhoea in Africa, to date there are no reports on whole genomic analysis of African G2P[4] strains. In this study, the nearly complete genome sequences of two Kenyan G2P[4] strains, AK26 and D205, detected in 1982 and 1989, respectively, were analysed. Strain D205 exhibited a DS-1-like genotype constellation, whilst strain AK26 appeared to be an intergenogroup reassortant with a Wa-like NSP2 genotype on the DS-1-like genotype constellation. The VP2-4, VP6-7, NSP1, NSP3 and NSP5 genes of strain AK26 and the VP2, VP4, VP7 and NSP1-5 genes of strain D205 were closely related to those of the prototype or other human G2P[4] strains. In contrast, their remaining genes were distantly related, and, except for NSP2 of AK26, appeared to originate from or share a common origin with rotavirus genes of artiodactyl (ruminant and camelid) origin. These observations highlight the complex evolutionary dynamics of African G2P[4] rotaviruses.

Full genomic analysis of a simian SA11-like G3P[2] rotavirus strain isolated from an asymptomatic infant: identification of novel VP1, VP6 and NSP4 genotypes.

We report here the full genomic analysis of a simian SA11-like G3P[2] group A rotavirus (GAR) strain, B10, isolated from an asymptomatic infant in Kenya in 1987. By nucleotide sequence identities and phylogenetic analyses, the VP7-VP4-VP2-VP3-NSP1-NSP2-NSP3-NSP5 genes of strain B10 exhibited maximum genetic relatedness to those of the different isolates of simian strain SA11, and were assigned to the G3-P[2]-C5-M5-A5-N5-T5-H5 genotypes, respectively. On the other hand, the VP1, VP6 and NSP4 genes of strain B10 did not belong to any of the established GAR genotypes, and therefore, were assigned to new genotype numbers R8, I16 and E13, respectively, by the Rotavirus Classification Working Group. These observations suggested that strain B10 might have originated from reassortment event/s involving simian SA11-like strains and GAR strains from unknown animal host species (possibly other wild animals) preceding transmission to humans. Alternatively, considering the lack of data on simian GARs, it might be also possible that the VP1, VP6 and NSP4 genes of strain B10 are those of unknown simian strains, and that strain B10 might be a typical simian strain that was directly transmitted to humans. Therefore, either hypothesis pointed towards a rare instance of possible direct transmission of GARs from an animal host (possibly a monkey or some other wild animal) to humans. This was corroborated by the presence of different species of wild animals including non-human primates, and unhygienic conditions at the sampling site. To our knowledge, the present study is the first report on the detection of a simian SA11-like G3P[2] GAR strain in humans.

Full genomic analysis of a G8P[1] rotavirus strain isolated from an asymptomatic infant in Kenya provides evidence for an artiodactyl-to-human interspecies transmission event.

Group A rotavirus (GAR) G8P[1] strains, found sometimes in cattle, have been reported rarely from humans. Therefore, analysis of the full genomes of human G8P[1] strains are of significance in the context of studies on interspecies transmission of rotaviruses. However, to date, only partial-length nucleotide sequences are available for the 11 genes of a single human G8P[1] strain, while the partial sequences of two other strains have been reported. The present study reports the first complete genome sequence of a human G8P[1] strain, B12, detected from an asymptomatic infant in Kenya in 1987. By nucleotide sequence identities and phylogenetic analyses, the full-length nucleotide sequences of VP7-VP4-VP6-VP1-VP2-VP3-NSP1-NSP2-NSP3-NSP4-NSP5 genes of strain B12 were assigned to G8-P[1]-I2-R2-C2-M2-A3-N2-T6-E2-H3 genotypes, respectively. Each of the 11 genes of strain B12 appeared to be more related to cognate genes of artiodactyl (ruminant and/or camelid) and/or artiodactyl-derived human GAR strains than those of most other rotaviruses. Strain B12 exhibited low levels of genetic relatedness to canonical human GAR strains, such as Wa and DS-1, ruling out the possibility of its origin from reassortment events between artiodactyl-like human and true human strains. These observations suggest that strain B12 might have been directly transmitted from artiodactyls to humans. Unhygienic conditions and close proximity of humans to livestock at the sampling site might have facilitated this rare event. This is the first report on a full genomic analysis of a rotavirus strain from Kenya. To our knowledge, strain B12 might be the oldest G8 strain characterized molecularly from the Africa continent.

Characterization of human rotavirus strains from children with diarrhea in Nairobi and Kisumu, Kenya, between 2000 and 2002.

Rotavirus infection is a major cause of diarrheal illness and hospitalization in children <5 years old in Kenya and has been described in various settings and locations across the country and for different time points. In this study, we expand on the molecular characterization of rotavirus strains collected in Nairobi and Kisumu, Kenya, between 2000 and 2002. Rotavirus strains were typed by reverse-transcription polymerase chain reaction and characterized using VP6 monoclonal antibodies and RNA electrophoresis of the viral genome. A large proportion of specimens could not be genotyped; 41% did not produce a G type result, and 43% did not produce a P type result. Of the strains that could be genotyped, G1P[8] strains were predominant, followed by G2P[4] strains. In addition, G8 and G9 strains were seen in similar proportions Interestingly, the G and P combinations were more diverse among G8 and G9 rotavirus strains, suggesting the recent introduction of these strains into the human population. These observations are a link between the occasional observation of G8 and G9 strains at the turn of the century and the high predominance of G9P[8] strains observed in Kenya in 2005.

The epidemiology of human rotavirus associated with diarrhoea in Kenyan children: a review.

Rotavirus gastroenteritis still remains a major cause of morbidity and mortality among young children in developing countries, with approximately 150,000-200,000 deaths occurring annually in sub-Saharan Africa. We reviewed papers published over the last 30 years on the epidemiology of rotavirus diarrhoea among the hospitalized and out-patient children in Kenya. The analysis shows rotavirus prevalence of 6-56% with diarrhoea occurring throughout the year and generally exhibiting distinct peaks during the dry months. Among the common genotype, G1 was the most predominant up to the year 2002 but more recently there has been an emergence of genotype G9 as the most predominant genotype and to a less extent G8. It is important to continue rotavirus surveillance in Kenya to determine accurately the burden of rotavirus disease and the emerging new genotypes. This will assist policy makers in decision making on rotavirus vaccine introduction and determining the impact of the vaccine.