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Agents affecting health of mother and child in a rural area of Kenya. XI. Antibodies against rotavirus in sera from children living in the Machakos District of Kenya.

207 sera from children under 5 years of age and living in the Machakos District in Kenya were tested in the Complement Fixation Test for antibodies against rotavirus. Two different antigens were used. The superiority of 'O' antigen over Nebraska calf diarrhoea virus antigen was confirmed. After a fall to 29 percent in the 6-8 months age group, the percentage of children with antibodies quickly rises with age to 80 percent at the age of 24 months and to practically 100 percent at the age of 30 months. This age-immunity curve suggests that the majority of children contract infections with rotavirus between 6 and 23 months of age. This is conform the pattern usually found in temperate climate countries.

Antibodies, Viral

Agents affecting health of mother and child in a rural area of Kenya. X. Haemagglutination inhibiting antibodies against influenza A (H3N2) and influenza B virus in sera from children living in the Machakos District of Kenya.

In the framework of the Machakos Project bloodcollections from random samples of children under 5 years of age and living in a rural area of Kenya were done with regular intervals, Serum samples of two collections were tested for haemagglutination inhibiting antibodies against influenza A and B viruses. The children had been exposed to the Hong Kong/1/68 (H3N2) virus or its variants during one, two or three episodes of circulation and probably to only one epidosde of B/Hong Kong/8/73 virus. The results can be explained by the assumption that 30-40 percent of non-immune children were infected per epidosde of exposure to influenza A and not more than 12 percent per episode of influenza B circulation.

Antibodies, Viral

Economic losses resulting from bovine cysticercosis with special reference to Botswana and Kenya.

Economic losses from cysticercosis are determined by disease prevalence, grade of animals infested, potential markets, prices of cattle and treatment costs for detained carcasses. The main features of the livestock economics of Botswana and Kenya are discussed. Botswana is more dependent on meat exports than Kenya and its cattle prices are much higher. The incidence of cysticercosis at export abattoirs in Botswana and Kenya is about 8 and 20% respectively. Annual losses in Botswana now approach 0-5 million pounds, while in Kenya they are about 1 million pounds. The loss per animal slaughtered is 2-25 pounds in Botswana and 1-50 pounds in Kenya. Some implications for veterinary research in this area are examined. Blanket treatment with a drug or vaccine would only be economical where prevalence was very high. An in vivo diagnostic test would be of use mainly with high value cattle.

Animals

Xerophthalmia and measles in Kenya.

In many African countries measles is considered to be an important cause of blindness. On the basis of his observations in Kenya and Tanzania in 1972 Franken presumed, however, that in the majority of these cases xerophthalmia was the real cause of blindness, precipitated by the "catalyst" measles. In order to gain a better understanding of this important complicated problem, we performed in the first half of 1974 an investigation in Kenya into the prevalence of xerophthalmia. In December 1974 we had the opportunity to evaluate our Kenyan findings on Java, in the company of Dr. J. ten Doesschate and Professor H.A.P.C. Oomen. The results of this investigation in Kenya and Indonesia are presented in this thesis. (see article) 1. Xerophthalmia occurred nearly everywhere in Kenya in 1974. This demonstrates the prevalence of xerophthalmia in communities which - do not have rice but - have maize for their staplefood. 2. Xerophthalmia appears to be the main cause of blindness in Kenyan children. 3. Measles often plays - by means of local and general "catalysing" effects - an important role in the development of blindness caused by xerophthalmia. 4. In well-nourished children measles is of no consequence as a cause of blindness. 5. Vital staining by 1% rose bengal or 1% lissamine green appears to be a real asset for the early diagnosis of xerophthalmia in Health Centres and in field surveys. This method is therefore of great importance for the prevention of severe, blindness inducing vitamin A deficiency.

Adolescent

Complexity of schistosome vector bulinine snails in Kenya: Insights from nuclear genome size variation, complete mitochondrial genome sequence, and morphometric analysis.

Investigations of nuclear genome size, complete mitochondrial genome (mitogenome) sequence, and morphometrics were conducted on specimens of Bulinus snails (Gastropoda: Planorbidae) collected from 14 locations across the east coast, central Kenya, and western Kenya around the Lake Victoria region (November 2013 and January 2024). Flow cytometry measurements of DNA content (C-value) revealed unexpected variation in nuclear genome size, with diploid Bulinus africanus and B. forskalii species groups showing C-values ranging from 0.76 to 1.98 pg, while tetraploid B. truncatus had a C-value of 1.82 pg. Additionally, C-values for six B. globosus specimens from different localities ranged from 1.43 to 1.98 pg. These findings suggest that bulinine snails, particularly the B. africanus species group, have undergone genome expansion, whole genome duplication (polyploidization), or both, which have not been previously recognized. Next-generation sequencing was performed to determine and annotate 14 complete mitogenome sequences. Despite the well-conserved arrangement of protein-coding genes, two versions of mtDNA genome structure, distinguished by the tRNA-D (Asp) location, were found, designated as DCF (Asp-Cys-Phe) type (in the B. forskalii group and the B. truncatus/tropicus complex) and CF (Cys-Phe) type (in the B. africanus group). Phylogenetic analyses based on complete mtDNA sequences of bulinines from Kenya, along with cytochrome c oxidase subunit I (COX1) sequences from various localities across Africa, contributed to resolving species identities and provided further support for the presence of multiple or cryptic species in the taxon B. globosus. A landmark-based morphometric analysis was ineffective in distinguishing these species. This study reveals unexpected nuclear genome size variation, provides new mitogenome sequences, and highlights the limitations of morphological analysis. It offers valuable insights into the cytogenetics, polyploidy, genomics, taxonomy, and evolution of bulinines, which serve as intermediate hosts for schistosomes responsible for human urogenital schistosomiasis and intestinal schistosomiasis in domestic and wild mammals.

Animals

Acute haemorrhagic conjunctivitis and enterovirus 70 in Kenya.

The pandemic of acute haemorrhagic conjunctivitis that started in Ghana in 1969 and spread to many countries in Africa, Asia and Europe reached Kenya in April 1971. From one patient virus was isolated. This was possibly the first strain ever isolated of Enterovirus 70. Identification took time and was finished long after the publication of isolation of the new virus in Japan. Cross neutralization tests with the virus from Japan showed close relationship between the two. During a second epidemic in Kenya in 1974 many more strains of the virus were isolated. The history of isolation and identification and the clinical picture of the disease as seen in Kenya are described.

Acute Disease

Poliomyelitis: Epidemiology and prophylaxis. 6. Geographic synchronism in poliomyelitis epidemics in Kenya.

In the 1950s, van Loghem drew attention to what he called "synchronism" in the epidemics of poliomyelitis in western Europe. The 1952 epidemic in the Netherlands affected Belgium and neighbouring parts of the Federal Republic of Germany at the same time. A comparable phenomenon is described from Kenya. Notwithstanding the fact that in the three population concentrations of the country the three poliovirus types may well be endemic, epidemics of poliomyelitis repeatedly occurred synchronously in these areas. However, there seems to be no synchronism between poliomyelitis epidemics in Kenya and those in neighbouring East African countries. Tentative explanations are put forward for the similarities and differences between Europe and East Africa. The importance of the phenomenon as observed in Kenya for control by mass immunization campaigns is stressed.

Humans

The economic effects of trypanosomiasis in sheep and goats at a range research station in Kenya.

A study on the economic effects of naturally acquired trypanosomiasis in sheep and goats over a period of 35 weeks under range conditions in the Kiboko area of Kenya indicated that the financial loss from reduced weight gain and death amounted to 36.2 and 62.9 Kenya shillings per head for goats and sheep respectively. This was derived from the weight loss through death together with the reduced weight gain of the survivors compared with treated animals. The study also compared the efficacy of 3 drug regimes in goats and suggests that although quinapyramine (prophylactic) B.vet.C. provided the longest protective period, the weight increase of the stock under isometamidium chloride treatment was higher. The benefits of the drugs used are discussed.

Animals

Tuberculosis in Kenya: a second national sampling survey of drug resistance and other factors, and a comparison with the prevalence data from the first national sampling survey. An East African and British Medical Research Council Co-operative Investigation.

A survey was carried out in 1974 in the same random sample of 11 of 30 districts in Kenya that were surveyed in 1964, to obtain information on (a) the proportion of patients with pulmonary and with extra-pulmonary tuberculosis, (b) the prevalence of bacteriologically-positive pulmonary tuberculosis, (c) the prevalence of initial and acquired drug resistance, (d) the radiographic extent and type of pulmonary disease, and (e) the changes that had occurred in the 10-year period. Of 1490 patients, 88.5% had pulmonary tuberculosis only, 3.0% had both extra-pulmonary and pulmonary tuberculosis and 8.6% had extra-pulmonary tuberculosis only. Of the 172 patients with extra-pulmonary tuberculosis, 51% had lymph node involvement, 24% bone and joint disease and 9% a pleural effusion. Of the 1362 patients with pulmonary tuberculosis (with or without extra-pulmonary tuberculosis) 94% had no history of previous chemotherapy, fewer than 1% a history of possible and 6% a history of definite previous chemotherapy. (The proportions for the patients with extra-pulmonary tuberculosis only were 94%, 1% and 5% respectively.) A sputum specimen was produced by 1096 (80%) of the patients with pulmonary tuberculosis; 69% of smear results were positive, as were 74% of the culture results. In 2 (0.25%) of the 807 patients with a positive culture the strain was identified as being neither M. tuberculosis nor M. bovis. Of 702 patients with no history of previous chemotherapy and a sensitivity test result available, 10.1% had a strain resistant to isoniazid and/or streptomycin, 7.3% to isoniazid alone, 1.4% to streptomycin alone and 1.4% to both drugs. Of 1133 patients with chest radiographs available and a diagnosis in Kenya of pulmonary tuberculosis, a lung lesion or a pleural effusion was reported at independent assessment in London for 91%. Gross, extensive or moderate disease was present in 73% of the patients and cavitation was present in 72%. The radiographic disease was classified as acute in 31%, mixed-acute in 52%, mixed in 12% and chronic in 5%. The disease in children was usually less extensive, less often cavitated, and more acute than in adults. A comparison of the prevalence data in 1974 with that in 1964 suggested that there was a modest decline in the incidence of tuberculosis but that the characteristics of the registered patients and their disease were very similar in all respects; the disease was just as extensive radiographically and cavitation was, if anything, more common and more extensive in 1974 than in 1964.

Adolescent

Studies of the relationship between Schistosoma and their intermediate hosts. III. The genus Biomphalaria and Schistosoma mansoni from Egypt, Kenya, Sudan, Uganda, West Indies (St. Lucia) and Zaire (two different strains: Katanga and Kinshasa).

The compatibility between strains of Schistosoma mansoni from Egypt, Kenya, Sudan, Uganda, the West Indies, and Zaire (two strains which came from Katanga and from Kinshasa), and various species and strains of Biomphalaria, i.e. Biomphalaria pfeifferi, B. alexandrina, B. glabrata and B. camerunensis was investigated. Data as mortality, rate of infection of the surviving snails, duration of infection, cercarial production per day per positive snail, etc., were observed. The main emphasis was placed on determining the total cercarial production per 100 exposed snails for each snail population. It was possible to infect all the tested populations of B pfeifferi with the various strains of S. mansoni, but the observation as e.g. TCP/100 exposed snails varied greatly according to the population of snail and the strain of S. mansoni. The results for the remaining species of Biomphalaria varied greatly, depending on the combination, e.g. B. alexandrina was only susceptible to the local S. mansoni from Egypt. The highest TCP/100 exposed snails was more than 1 million for the strains of S. mansoni from Egypt, Kenya and the West Indies in B. alexandrina, B. pfeifferi and B. glabrata, respectively. The next group, with a TCP/100 exposed snails on 7--800 000 consists of S. mansoni from Sudan, Uganda and Zaire (Katanga) all in B. pfeifferi. The last tested strain of S. mansoni, Zaire (Kinshasa) yielded a cercarial production on 500 000 per 100 exposed snails in B. pfeifferi and B. camerunensis. The shortest prepatent period, 19 days, was observed for S. mansoni from Kinshasa, Zaire, in B. camerunensis, and the longest prepatent period, 25 days, was found for strains from Egypt and from the West Indies in B. alexandrina and B. glabrata, respectively. In general, a very long duration of infection, lasting up to 200 days, was observed.

Animals

Genomic and clinical epidemiology of SARS-CoV-2 in coastal Kenya: insights into variant circulation, reinfection, and multiple lineage importations during a post-pandemic wave.

BACKGROUND: Between November 2023 and March 2024, coastal Kenya experienced another wave of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections detected through our continued genomic surveillance. Herein, we report the clinical and genomic epidemiology of SARS-CoV-2 infections from 179 individuals (a total of 185 positive samples) residing in the Kilifi Health and Demographic Surveillance System (KHDSS) area (~ 900 km2). METHODS: We analyzed genetic, clinical, and epidemiological data from SARS-CoV-2 positive cases across pediatric inpatient, health facility outpatient, and homestead community surveillance platforms. Phylogenetic analyses were performed using maximum-likelihood and Bayesian frameworks. Temporal trends were summarized, comparisons conducted using Kruskal-Wallis and Wilcoxon tests, and associations examined using univariate and multivariable logistic regression models. RESULTS: Sixteen SARS-CoV-2 lineages within 3 subvariants [XBB.2.3-like (58.4%), JN.1-like (40.5%), and XBB.1-like (1.1%)] were identified. The symptomatic infection rate was estimated at 16.0% (95% CI, 11.1-23.9%) based on community testing regardless of symptom status and did not differ across the subvariants (p = 0.13). The most common infection symptoms in community cases were cough (49.2%), fever (27.0%), sore throat (7.3%), headache (6.9%), and difficulty in breathing (5.5%). One case succumbed to the infection. Genomic analysis of the virus from serial positive samples confirmed repeat infections among 5 participants under follow-up (median interval 21 days, range 16-95 days); in 4 participants, the same virus lineage was responsible in both episodes, whereas 1 participant had a different lineage in the second compared with the first episode. Phylogenetic analysis including > 18,000 contemporaneous global sequences provided evidence for at least 38 independent virus introduction events into the study area (KHDSS) during the wave, the majority likely originating in North America and Europe. CONCLUSIONS: Our study highlights that coastal Kenya, like most other localities, continues to face new SARS-CoV-2 infection waves characterized by circulation of new variants, multiple lineage importations, and reinfections. Locally, the virus may circulate unrecognized, as most infections are asymptomatic in part due to high population immunity after several waves of infection. Our findings highlight the need for sustained SARS-CoV-2 surveillance to inform appropriate public health responses, such as scheduled vaccination for populations at risk of severe infection.

COVID-19

Molecular Epidemiology of Human Metapneumovirus in Kilifi, Coastal Kenya, 2016-2017 and 2021-2024.

BACKGROUND: Human metapneumovirus (hMPV) is a major contributor of acute respiratory infections (ARI) in childhood and vulnerable adults. It comprises two antigenically distinct lineages (A and B), with multiple sub-lineages. Genomic analyses of hMPV strains enable monitoring of viral evolution and transmission to inform future interventions but remain underutilized in Africa. METHODS: We generated 52 near-complete hMPV genomes from respiratory samples collected in Kilifi, Coastal Kenya, using a tiled-amplicon approach and Oxford Nanopore Technologies sequencing. These samples had been identified as hMPV positive by quantitative PCR during (a) a multi-facility outpatient ARI surveillance in nine health facilities in Kilifi between 2016 and 2017, and 2021 to 2023 and (b) a community-based respiratory infection cohort surveillance study between 2023-2024 that sampled enrolled participants irrespective of symptom status. RESULTS: Of the 192 positive samples analyzed from the two studies, children under 5 years accounted for most hMPV cases (134/186, 72%). 52 samples were sequenced (>70% genome coverage), and hMPV-A (27/52, 53.8%) and hMPV-B (25/52, 46.2%) lineages were identified. The recovered sequences mapped into sub-lineages A2c (27/52, 53.8%), B1 (12/52, 21.2%), and B2b (13/52, 25%). A shift in the predominant sub-lineage was observed from B2b (2016) to B1 (2021), and finally to A2c-wild type (2023). In February 2021, for the first time, we detected a single A2c strain with a 111-nucleotide duplication in the G gene among Kenyan samples. CONCLUSION: Our study expands the global nucleotide sequence database for hMPV by adding new whole-genome sequences from Kenya collected over the last decade. It highlights the ongoing replacement of locally predominant hMPV lineages and the importation and local transmission of globally circulating strains. These findings underscore the importance of sustained hMPV genomic surveillance to detect emerging variants and monitor lineage circulation patterns that may impact viral transmission, molecular detection, and future control measures.

A2c-111nt-dup

Characterization of West Nile virus Koutango lineage from phlebotomine sandflies in Kenya.

The West Nile virus (WNV), primarily transmitted by mosquitoes, is one of the most widespread flaviviruses globally, with past outbreaks occurring in the USA and Europe. Recent studies in parts of Africa, including Kenya, have identified the West Nile virus Koutango lineage (WN-KOUTV) among phlebotomine sandfly populations, however, our understanding of this virus remains limited. This study aimed to characterize WN-KOUTV from phlebotomine sandflies. Sandflies were sampled between 12th -16th March 2021 and 16th -20th March 2023 from six villages each in Baringo and Isiolo Counties, using CDC light traps. Female sandflies were taxonomically identified and pooled based on genus and site of collection. Virus isolation was performed in Vero cells. Viral genomes were determined using next-generation sequencing. Phylogenetic and molecular clock analyses were done to decipher the virus's evolutionary relationships. Comparative analyses of amino acid sequences were performed to determine variations. Protein modeling in Pymol was conducted to elucidate variations in key protein regions. Evolutionary pressure analysis investigated the selection pressures on the virus. In vitro experiments were done to investigate the virus growth kinetics in mammalian Vero E6 and mosquito C6/36 cells. We report the isolation of WN-KOUTV from Salabani in Baringo and Aremet in Isiolo, Kenya. The isolated WN-KOUTVs clustered with previously identified WN-KOUTV strains. Comparative analysis revealed a unique amino acid at NS5 653. The WN-KOUTV lineage as a whole is under purifying selective pressure, with diversifying pressure acting at site NS3 267. The current WN-KOUTV replicated in Vero E6 and C6/36 cells comparable to West Nile virus Lineage 1a, isolated from mosquitoes. Subsequent isolations of WN-KOUTV in phlebotomine sandflies suggest potential vectors, however, vector competence studies would confirm this. Replication in mammalian and insect cell lines suggests there may exist a vector/host relationship. We speculate the close genetic relationship of WN-KOUTV strains from East and West Africa may potentially be enabled by bird migratory routes between the two regions. If proven, this could point to a potential future pandemic pathway for this virus.

Animals

Endemic goitre in Kenya: the pattern of iodine excretion.

A national random sample survey of iodine excretion among primary schoolchildren in Kenya was carried out in 1974/75, in order to monitor the endemic goitre situation and its control more accurately and to gain more insight in the geographical distribution of iodine deficiency in the country. Urine samples were collected in 59 randomly chosen primary schools in 32 districts from which the individual iodine/creatinine ratios were determined. The results are analysed and presented per school, per district and per province, showing areas of normal, moderate and low iodine intake, and latter coinciding with the known goitre areas in Kenya. Although some doubts have been cast on the methods used in this survey and the consequent reliability of its conclusions, the authors consider its publication yet justified.

Child

Radioimmunochemical characterization of hemoglobins Lepore and Kenya: unique antigenic determinants located on hybrid hemoglobins.

Antisera were produced in rabbits to the three known types of Lepore hemoglobins, which contain hybrid delta-beta non-alpha-chains, and to hemoglobin Kenya, which has a hybrid gamma-beta non-alpha-chain. By using a sensitive radioimmunoassay technique, the absorbed antisera were shown to contain an antibody population that was specific for the hybrid hemoglobin and did not cross-react with normal hemoglobins. However, with the absorbed Lepore-specific antisera, the three known types of Lepore hemoglobins were antigenically indistinguishable from each other, suggesting that antibodies are not produced to the primary structural differences which define the three non-alpha-chains of the Lepore hemoglobins. These studies demonstrate that the non-alpha-subunits of hemoglobins Lepore and Kenya possess unique antigenic determinant sites, evidently resulting from an altered polypeptide conformation.

Animals

Genomic epidemiology of coxsackievirus A24 variant during the 2024 acute hemorrhagic conjunctivitis outbreak in Coastal Kenya.

Several African countries experienced a surge in acute hemorrhagic conjunctivitis (AHC) cases in 2024. Investigations in Kenya, Mayotte (an Indian Ocean island) and Tanzania identified coxsackievirus A24 variant (CVA24v) as the causative agent. To date, however, limited genomic data exist to elucidate the sources, epidemiology, and evolution of CVA24v in Africa. We generated 245 CVA24v genomes from samples collected between January and September 2024 in coastal Kenya, representing the largest outbreak CVA24v genomic data set available globally. Phylogenetic analysis showed that these viruses belonged to genotype IV, falling into two major clusters that differed by 52 nucleotide and five amino acid changes, and with an inter-species recombination event involving another enterovirus in the 3Dpol gene. Notably, the Kenyan sequences clustered closely with contemporaneous Africa (2024) sequences, specifically Mayotte and Malawi, reflecting a regionally connected CVA24v outbreak, but were distinct from those sampled previously in Asia in 2023, with phylodynamic analysis revealing that the Most Recent Common Ancestor of Kenyan sequences existed between June and October 2023. In summary, this study provides the first detailed genomic analysis of CVA24v from Africa to inform future surveillance and control strategies.

Journal Article