Nicholas M. Kiulia

Burden and epidemiology of rotavirus diarrhea in selected African countries: preliminary results from the African rotavirus surveillance network.

Severe rotavirus diarrhea in children <5 years of age is a major public health problem; however, limited regional and country specific data on rotavirus disease burden are available from sub-Saharan Africa. In June 2006, the World Health Organization Regional Office for Africa initiated rotavirus surveillance in selected African countries. With use of standardized methodology developed by the World Health Organization, children <5 years of age who were hospitalized with severe diarrhea were enrolled, and stool specimens were collected for detection of rotavirus strains with use of a commercial enzyme immunoassay. Rotavirus strains were further characterized for G and P types with use of a reverse-transcriptase polymerase chain reaction. From June 2006 through December 2008, rotavirus surveillance was established at 14 sites in 11 African countries. Of 5461 stool samples collected from children enrolled in 8 countries with 1 or 2 complete years of data, 2200 (40%) were positive for rotavirus. Ninety percent of all rotavirus hospitalizations occurred among children aged 3-12 months. Predominant types included G1P[8] (21%), G2P[4] (7%), and P [8] (29%); however, unusual types were also detected, including G8P[6] (5%), G8P[8] (1%), G12P[6] (1%), and G12P[6] (1%). A high percentage of mixed rotavirus infections was also detected. These preliminary results indicate that rotavirus is a major cause of severe diarrheal disease in African children.

Cyclospora papionis, Cryptosporidium hominis, and Human-Pathogenic Enterocytozoon bieneusi in Captive Baboons in Kenya

ABSTRACT Cyclospora papionis, Cryptosporidium hominis, and Enterocytozoon bieneusi were detected in 42 (17.9%), 6 (2.6%), and 29 (12.3%) of 235 newly captured baboons in Kenya, respectively. Most C. hominis subtypes and E. bieneusi genotypes found have been detected in humans in the area, suggesting that cross-species transmission of cryptosporidiosis and microsporidiosis is possible.

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.

Evidence of a Recombinant Wild-Type Human Astrovirus Strain from a Kenyan Child with Gastroenteritis

ABSTRACT A human astrovirus (HAstV) strain from Kenya was characterized by nucleotide sequence analysis. Sequences from open reading frame 1a (ORF1a) clustered with genotype 6/7, those from ORF1b clustered with genotype 3, and those from ORF2 clustered with genotype 2. A recombination point in the ORF1b-ORF2 junction was identified, with a second possible recombination point within the ORF1a region.

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.

Rotavirus G and P types circulating in the eastern region of Kenya: predominance of G9 and emergence of G12 genotypes.

Background: The World Health Organization has recommended that rotavirus (RV) vaccines be included in all national immunization programs as part of a strategy to control RV-associated diarrheal diseases. Hospital-based surveillance of RV infection is therefore crucial in monitoring the impact pre- and post-vaccine introduction and also to document changes in genotype distribution. This study sought to determine the RV genotypes circulating in the eastern region of Kenya before introduction of the RV vaccine. Methods: During September 2009 to August 2011, 500 stool samples were collected from children <5 years of age admitted for acute diarrhea in hospitals in the eastern region of Kenya and analyzed for the presence of group A RV using an enzyme immunoassay. G and P genotypes were determined using hemi-nested reverse transcriptase polymerase chain reaction. Results: One hundred and eighty nine out of 500 (38%) samples analyzed were positive for rotavirus. The following G types were detected: G9 (50.9%), G1 (26.8%), G8 (12.1%), G12 (3.1%), G2 (0.6%), mixed G (1.3%) and 5.1% were G nontypeable. P types detected included: P[8] (63.7%), P[4] (12.1%), P[6] (4.5%), mixed P (7.6%) and 12.1% were P nontypeable. The most dominant strain was G9P[8] (35%), followed by G1P[8] (26.8%), G8P[4] (9.6%), G12P[6] (2.5%), G9P[6] (1.9%), G9P[4] (1.3%), G8P[8] (1.3%), and G2P[4] (0.6%). Conclusions: The present study demonstrates the recurring changing genotypes of RV circulating in Kenya, with genotypes G9, G1 and G8 being the dominant strains circulating in the eastern region of Kenya between 2009 and 2011. Additionally, G12 genotype was detected for the first time in Kenya.

Multilocus sequence typing of Enterocytozoon bieneusi: Lack of geographic segregation and existence of genetically isolated sub-populations☆

The population structure of Enterocytozoon bieneusi was examined by multilocus sequence typing (MLST) of 64 specimens from AIDS patients in Peru, Nigeria, and India and five specimens from captive baboons in Kenya using a combination of the ribosomal internal transcribed spacer (ITS) and four microsatellite and minisatellite markers. Parasites in different geographic locations (Peru, India, and Nigeria) all had strong and significant linkage disequilibrium (LD) and only limited recombination, indicative of a clonal population structure in E. bieneusi from each location. When isolates of various geographical areas were treated as a single population, phylogenetic analysis and substructural analysis using STRUCTURE found no evidence for the existence of geographically segregated sub-populations. Nevertheless, both analyses revealed the presence of two major genetically isolated groups of E. bieneusi: one (sub-population 1) contained all isolates of the anthroponotic ITS genotype A, whereas the other (sub-population 2) harbored isolates of multiple ITS genotypes with zoonotic potential. This was also supported by FST analysis. The measurement of LD and recombination rates indicated that sub-population 2 had a clonal population structure, whereas sub-population 1 had an epidemic population structure. The data confirmed the existence of genetic sub-populations in E. bieneusi that may be transmitted differently in humans.

High prevalence of species D human adenoviruses in fecal specimens from Urban Kenyan children with diarrhea

Human adenoviruses (HAdVs) cause a wide range of clinical syndromes and are classified in seven species, A–G, comprising 52 serotypes. HAdV‐A31, ‐F40, and ‐F41 have been associated with diarrhea in infants and young children. In developing countries gastroenteritis is a major cause of morbidity and mortality in children and, in comparison to rotaviruses, there are no data on the HAdVs associated with diarrhea in pediatric patients in Kenya. This study investigates the prevalence and genotypes of HAdVs in 278 stool specimens (211 diarrheal; 67 non‐diarrheal) from children ≤14 years of age in urban and rural areas in Kenya. Stool specimens were screened for HAdVs using a nested polymerase chain reaction and the HAdVs genotyped by sequence analysis of a conserved hexon gene fragment. HAdVs were detected in 104/278 (37.4%) of the stool specimens: 35/43 (81.4%) of diarrheal and 10/61 (16.4%) of non‐diarrheal stool specimens from children in an urban hospice; 25/94 (26.6%) of diarrheal specimens from urban children and 34/80 (42.5%) of diarrheal specimens from children in a rural area. Species D HAdVs were identified as the most prevalent HAdV species in diarrheal stool specimens from urban children comprising 18/37 (48.6%) of the strains identified. In contrast HAdV species F predominated in pediatric diarrheal specimens from the rural area, being identified in 7/16 (43.8%) of the characterized strains. This study provides valuable new data on the prevalence and distribution of HAdV genotypes in diarrheal stool specimens in Kenya and Africa, and highlights the necessity for further investigations. J. Med. Virol. 82:77–84, 2010.

Human caliciviruses detected in HIV-seropositive children in Kenya.

The human caliciviruses (HuCVs) are important causes of gastroenteritis worldwide. Norovirus (NoV) and sapovirus (SaV) have been detected in HIV‐seropositive children but the genetic diversity of HuCVs circulating in these individuals is largely unknown. In this study the prevalence and genotype diversity of HuCVs circulating in Kenyan HIV‐positive children, with or without diarrhea, from the year 1999 to 2000 was investigated. The overall prevalence of HuCVs was 19% with NoV predominating at 17% (18/105) and SaV present in 5.7% (6/105) of specimens. Human CVs were detected in both symptomatic (24%) and asymptomatic (16%) children. Co‐infections with other enteric viruses were detected in 21.6% of children with diarrhea but only in 4.4% of children without diarrhea. Remarkable genetic diversity was observed with 12 genotypes (7 NoV, 5 SaV) being identified in 20 HuCV‐infected children. NoV genogroup II (GII) strains predominated with GII.2 and GII.4 each representing 27% of the NoV‐positive strains. The GII.4 strain was most closely related to the nonepidemic GII.4 Kaiso 2003 variant. Other NoV genotypes detected were GI.3, GII.6, GII.12, GII.14, and GII.17. Five different SaV genotypes (GI.2, GI.6, GII.1, GII.2, and GII.4) were characterized from six specimens. Diarrheal symptoms were not associated with any specific HuCV genotype. Overall the HuCV genotype distribution detected in this study reflects those in other studies worldwide. The strains detected are closely related to genotypes that have circulated on several continents since the year 2000. J. Med. Virol. 86:75–81, 2014.

The Effects of a Single Cervical Inoculation of Chlamydia trachomatis on the Female Reproductive Tract of the Baboon (Papio anubis)

BACKGROUND The baboon (Papio hamadryas anubis) can be transcervically instrumented, facilitating studies of intrauterine contraception and reproductive tract infection. We sought to determine if the baboon could become infected with a single cervical inoculation of Chlamydia trachomatis. METHODS Ten female baboons were randomized and inoculated cervically with C. trachomatis serovar E (or buffer alone). Animals underwent weekly clinical and laparoscopic evaluations for four weeks and at post-inoculation week 8, to monitor upper tract infection. Cervical culture and nucleic acid amplification testing (NAAT) were completed weekly throughout the study. Animals were euthanized at week 16 and the reproductive tracts were examined histologically. RESULTS All inoculated animals developed cervical infection. The average duration of positive NAAT results was 6.8 weeks (range 2-16). Two of eight (25%) animals tested positive from fallopian tube samples. Infected animals showed histological findings consistent with chlamydial infection, such as germinal centers. Five of ten animals seroconverted to C. trachomatis. CONCLUSIONS Baboons cervically inoculated once with C. trachomatis develop infection similar to humans, with a low incidence of upper tract infection. This novel model of Chlamydia infection closely resembles human disease and opens new avenues for studying the pathogenesis of sexually transmitted infections and contraceptive safety.