Predicting the long-term impact of rotavirus vaccination in 112 countries from 2006 to 2034: A transmission modeling analysis.

Rotavirus vaccination has been shown to reduce rotavirus burden in many countries, but the long-term magnitude of vaccine impacts is unclear, particularly in low-income countries. We use a transmission model to estimate the long-term impact of rotavirus vaccination on deaths and disability adjusted life years (DALYs) from 2006 to 2034 for 112 low- and middle-income countries. We also explore the predicted effectiveness of a one- vs two- dose series and the relative contribution of direct vs indirect effects to overall impacts. To validate the model, we compare predicted percent reductions in severe rotavirus cases with the percent reduction in rotavirus positivity among gastroenteritis hospital admissions for 10 countries with pre- and post-vaccine introduction data. We estimate that vaccination would reduce deaths from rotavirus by 49.1 % (95 % UI: 46.6-54.3 %) by 2034 under realistic coverage scenarios, compared to a scenario without vaccination. Most of this benefit is due to direct benefit to vaccinated individuals (explaining 69-97 % of the overall impact), but indirect protection also appears to enhance impacts. We find that a one-dose schedule would only be about 57 % as effective as a two-dose schedule 12 years after vaccine introduction. Our model closely reproduced observed reductions in rotavirus positivity in the first few years after vaccine introduction in select countries. Rotavirus vaccination is likely to have a substantial impact on rotavirus gastroenteritis and its mortality burden. To sustain this benefit, the complete series of doses is needed.

Norovirus GII.17 Predominates in Selected Surface Water Sources in Kenya.

In this study, the prevalence and genotypes of noroviruses (NoVs) in selected water sources from rural, urban and refugee settings in Kenya were investigated. Ten litres each of river, household and borehole water was collected in rural (Mboone River), urban (Nairobi and Mutoine River) and refugee (Dadaab refugee camp) settings. NoVs were recovered from the water samples by a glass wool adsorption-elution technique and/or PEG/NaCl precipitation. Nucleic acid was extracted using the automated MagNA Pure platform. NoVs were detected with singleplex real-time reverse transcription-polymerase chain reaction assays and characterised by nucleotide sequence analysis. NoVs were detected in 63% (25/40) of the selected water samples comprising GII (42.5%), GI (2.5%) and mixed GI/GII (17.5%) positive samples. The prevalence of NoVs in the Mutoine River (urban area) was higher than in the Mboone River (rural area) (P = 0.0013). Noroviruses GI.1, GI.3, GI.9, GII.4, GII.6, GII.12, GII.16 and GII.17 were identified, with GII.17 accounting for 76% (16/21) of the typed strains. The NoV GII.17 predominance differs to other studies in Africa and further surveillance of NoVs in clinical and environmental settings is required to clarify/elucidate this observation. As information regarding NoVs in Kenyan water sources is limited this report provides valuable new data on NoV genotypes circulating in environmental water sources and the surrounding communities in Kenya.

The detection of enteric viruses in selected urban and rural river water and sewage in Kenya, with special reference to rotaviruses.

AIM: To determine the occurrence of eight human enteric viruses in surface water and sewage samples from different geographical areas in Kenya. METHODS AND RESULTS: Enteric viruses were recovered from the water and sewage sources by glass-wool adsorption elution and/or polyethylene glycol/NaCl precipitation and detected by singleplex real-time and conventional PCR and reverse transcriptase-PCR assays. One or more enteric viruses were detected in nearly all sewage and river water samples except the urban Mbagathi River. The VP7 (G types) and the VP4 (P types) of the rotaviruses (RV) were characterized by multiplex nested PCR methods. The G and P types could be determined in 95·5% of the RV strains, respectively. Mixed G types were detected with G12 and G1 predominating, and unusual G types, G5 and G10, were present. P[4] predominated in the urban Karen sewage samples, while P[8] predominated in the urban and rural streams. CONCLUSIONS: The high prevalence of RVs in surface water highlights the importance of assessing the water sources used for domestic purposes for viral contamination. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates the benefit of environmental surveillance as an additional tool to determine the epidemiology of RVs and other enteric viruses circulating in a given community.

Baboon serum is superior to human or bovine serum albumin for baboon sperm capacitation and zona binding.

BACKGROUND: Baboon in vitro fertilization requires capacitated sperm inappropriate media. In this study, we compared the effect of baboon serum (Bas), human serum albumin (HSA) and bovine serum albumin (BSA) on baboon sperm capacitation. METHODS: Five males (n = 5) were electroejaculated and 43 oocytes retrieved from super-ovulated female baboons (n = 10). Each sperm sample was assessed for initial motility and concentration before and after swim-up. For swim-up, each sperm sample was incubated separately in Biggers-Whitten-Whittingham media containing either BaS, HSA, BSA or without protein supplementation (control). After swim-up, each sperm aliquot was incubated with two to three oocytes. The number of sperm bound to the zona was evaluated after overnight incubation. RESULTS: Sperm motility and zona binding was significantly higher after capacitation in media supplemented with BaS than in HSA or BSA or in media without protein supplementation (P < 0.05). CONCLUSION: Baboon serum is superior to HSA or BSA for baboon sperm capacitation and zona binding.

Vaginal histological changes of the baboon during the normal menstrual cycle and pregnancy.

BACKGROUND: A baboon, a non-human primate, is phylogenetically close to human and has been used to study in detail aspects of reproductive physiology that cannot be studied in humans for ethical reasons. OBJECTIVE: To determine the histological changes in baboon vagina associated with cyclic variations during normal menstrual cycle. SETTING: The experiments were carried out at Institute of Primate Research (IPR), Karen, Nairobi, Kenya. SUBJECTS: Nine adult healthy female olive baboons were used in this study. These baboons were monitored over a period of one year and found to have regular menstrual cycles. The vaginal biopsies were taken at different menstrual stages, fixed in 10% formalin and processed to evaluate histological changes. RESULTS: Observation of the histological sections of the biopsies by light microscopy showed that there were histological changes associated with cyclic variations in female olive baboon. During the luteal phase, menstrual phase and pregnancy the squamous epithelium was very thin. The layer gradually thickens throughout the proliferative phase and was thickest during the ovulation period. CONCLUSION: The changes in squamous epithelium suggest that the baboon vagina undergoes histological changes throughout the menstrual cycle which may be associated with hormonal variations. The data from this study also suggest that olive baboon is a good model for investigating possible effects of hormonal contraceptives on vaginal epithelium and the mechanism of female heterosexual transmission of HIV.

Molecular characterisation of the rotavirus strains prevalent in Maua, Meru North, Kenya.

BACKGROUND: Rotavirus is the most common cause of severe infantile diarrhoea disease in infants and young children below five years worldwide. Rotavirus is associated with high cases of morbidity and mortality and it is estimated that up to 650,000 deaths in young children occur annually in the less developed countries and approximately 150,000-200,000 deaths occur in Africa alone. OBJECTIVE: To characterise the circulating rotavirus strains in Maua, Meru North district, Kenya. DESIGN: A prospective study to investigate and characterise rotavirus serotypes/genotypes and electropherotypes in infants and children with severe diarrhoea hospitalised and/or attending the outpatient department of Maua Methodist Hospital during the period April 2004 to September 2005. SETTING: Maua Methodist Hospital, Meru North, Kenya. SUBJECTS: Faecal samples were collected from 135 infants and children with acute diarrhoea and were screened first for the presence of human Group A rotavirus antigen using commercially available enzyme linked immunosorbent assay kit (ELISA). The positive samples were evaluated by sodium dodecyl polycrylamide gel electrophoresis (SDS-PAGE) to determine the viral RNA electropherotype profile. Rotavirus strains were also genotyped using reverse transcriptase polymerase chain reaction (RT-PCR) of the VP7 gene. RESULTS: Assay of these samples with commercial ELISA showed that 17.8% (24/135) were positive for group A rotavirus antigen. Twenty of these ELISA positive samples were also analysed by SDS-PAGE of which 75% (15/20) gave detectable electropherotype pattern with the long electropherotype being predominant 80.0% (12/15) followed by the short RNA profile 20.0% (2/ 15). Seventeen of the ELISA positive samples were genotyped for VP7 and the results showed that G9 was the most predominant genotype comprising 47.1% (8/17) followed by G8 29.4% (5/17), GI 17.4% (3/17) and the mixed genotype was G8/G9 5.9% (1/17). Most patients with rotavirus infection were of the age of 3 - 60 months, with 79% being less than 18 months old. CONCLUSION: The overall prevalence of rotavirus infection in young children with diarrhoea hospitalised and/or attending the out-patient department of Maua Methodist Hospital was 17.8% with the predominant serotype being G9. These results show that rotavirus plays an important role in severe viral diarrhoea in young children in Maua Meru North district, Kenya. Furthermore, this high G9 rotavirus prevalence in Kenya may require vaccine trials to be held in Kenya so as to determine the efficacy of new rotavirus vaccine candidates that do not include the G9 serotype.