64 research outputs found
The mangrove forest as a feeding ground and nursery habitat for the ichthyofauna: Mida Creek in Kenya
peer reviewedMangrove forests are among the most productive ecosystems, sustaining both terrestrial and
aquatic fauna (Kathiresan, 2011). They are important to coastal fisheries by providing foraging and hiding places for commercially valuable fishes (Tomlinson, 1986; Rönnbäck 1999). This research investigated the fish assemblage of Mida Creek (Kenya, East Africa) as well as the presumed feeding and nursery functions of the area for the ichthyofauna present. This explorative study contributes to a Kenyan-Flemish project in which scientists aim to identify the impacts of human exploitation and management regimes of mangroves on biodiversity richness and abundance, including demersal fish. The species composition of the ichthyofauna of Mida and trophic interactions therein was studied for five representative sampling areas. These sites are located at various distances from local villages in order to include the effect of different degrees of human disturbance. Samples were collected during 5-6 consecutive days close to spring tide in mid July 2011. Fishes were caught using several types of passive fishing gears such as large and small fyke nets, gill nets and occasionally beach seine. Each individual was identified to species level, measured and weighed. We performed stomach content analysis to provide information about fish diet. Furthermore, stable isotope analysis was applied on most fishes in order to detect whether the source of primary production for the higher trophic levels is mangrove-related or not. A total of 29 fish species was found with a catch of 939 teleost specimens. Our analyses showed that a majority of fish belonged to the zoobenthivorous/omnivorous trophic mode, they were mainly feeding on invertebrates. Their
diet was quite similar over different locations and life stages. Two species (Sphyraena barracuda and Synodus variegatus) exhibited a mixed diet with a piscivorous preference. Results concerning the population structure suggested that the fish community of Mida consisted of both transient and resident species. Juveniles were, however, numerically more abundant in the whole area than adult specimens. Based on our restricted sampling period and methodology, we were not able to accurately detect human impacts on fish stock and species composition between locations. Finally, our results confirm that Mida Creek mangrove is an important habitat for the ichthyofauna especially for juvenile fishes. Its role as feeding and nursery ground appears well established
Polycyclic Aromatic Hydrocarbons (PAHs) and Estrogenic Compounds in Experimental Flue Gas Streams
Risk factors for community-acquired pneumonia among adults in Kenya: a case-control study.
BACKGROUND: Pneumonia is a leading cause of morbidity and mortality among adults worldwide; however, the risk factors for community-acquired pneumonia in Africa are not well characterized. METHODS: The authors recruited 281 cases of community-acquired pneumonia and 1202 hospital controls among patients aged ≥15 years who attended Kilifi District Hospital/Coast Provincial General Hospital in Kenya between 1994 and 6. Cases were admissions with an acute illness with ≥2 respiratory signs and evidence of consolidation on a chest radiograph. Controls were patients without signs of pneumonia, frequency matched by age, sex and hospital. Risk factors related to socio-demographic factors, drug use, clinical history, contact patterns and exposures to indoor air pollution were investigated by questionnaire, anthropometric measurements and laboratory assays. Associations were evaluated using a hierarchical logistic regression model. RESULTS: Pneumonia was associated with human immunodeficiency virus (HIV) infection (Odds Ratio [OR] 2.06, 95% CI 1.44-3.08), anemia (OR 1.91, 1.31-2.74), splenomegaly (OR 2.04, 95% CI 1.14-3.41), recent history of pneumonia (OR 4.65, 95% CI 1.66-12.5), history of pneumonia >2 years previously (OR 17.13, 95% CI 5.01-60.26), coryza in the 2 weeks preceding hospitalization (OR 2.09, 95% CI 1.44-3.03), current smoking (2.19, 95% CI 1.39-3.70), use of khat (OR 3.44, 95% CI 1.72-7.15), use of snuff (OR 2.67, 95% CI 1.35-5.49) and contact with several animal species. Presence of a Bacillus Calmette-Guerin (BCG) scar was associated with protection (OR 0.51, 95% CI 0.32-0.82). The risk factors varied significantly by sex. CONCLUSION: Pneumonia in Kenyan adults was associated with global risk factors, such as HIV and smoking, but also with specific local factors like drug use and contact with animals. Intervention strategies should account for sex-specific differences in risk factors
The epidemiology of fecal carriage of nontyphoidal Salmonella among healthy children and adults in three sites in Kenya
Background: Despite the importance of non-Typhoidal Salmonella (NTS) disease in Africa, epidemiologic data on carriage and transmission are few. These data are important to understand the transmission of NTS in Africa and to design control strategies.
Method: To estimate the prevalence of stool carriage of NTS in Kenya, we conducted a cross-sectional study in Kilifi, Nairobi, and Siaya, sites with a low, moderate and high incidence of invasive NTS disease, respectively. At each site, we randomly selected 100 participants in each age-group of 0–11 months, 12–59 months, 5–14 years, 15–54 years and ≥55 years. We collected stool, venous blood (for hemoglobin and malaria rapid tests), anthropometric measurements, and administered a questionnaire on Water Access Sanitation and Hygiene (WASH) practices. Stool samples were cultured on selective agar for Salmonella; suspect isolates underwent serotyping and antimicrobial susceptibility testing.
Result: Overall, 53 (3.5%) isolates of NTS were cultured from 1497 samples. Age-adjusted prevalence was 13.1% (95%CI 8.8–17.4) in Kilifi, 0.4% (95%CI 0–1.3) in Nairobi, and 0.9% (95%CI 0–2.0) in Siaya. Prevalence was highest among those aged 15–54 years (6.2%). Of 53 isolates; 5 were S. Enteritidis, 1 was S. Typhimurium. No S. Typhi was isolated. None of the risk factors were associated with carriage of NTS. All isolates were susceptible to all antibiotics tested, including ampicillin, chloramphenicol, ciprofloxacin and co-trimoxazole.
Conclusion:Â Prevalence of fecal carriage was high in Kilifi, an area of low incidence of invasive NTS disease and was low in areas of higher incidence in Nairobi and Siaya. The age-prevalence, risk factors, geographical and serotype distribution of NTS in carriage differs from invasive disease
Polycyclic Aromatic Hydrocarbons (PAHs) and Estrogenic Compounds in Experimental Flue Gas Streams
Polycyclic aromatic hydrocarbons (PAHs) and estrogenic compounds in experimental flue gas streams
The importance of combustion processes as a source of substances with estrogenic activity in the environment was investigated. Wood (nontreated and treated with wood preservatives), barbecue charcoal, meat, and kitchen waste were combusted in a laboratory-scale incinerator. Flue gas emissions (particulates and gaseous pollutants) were trapped in polyurethane foam cartridges. The cartridges were subjected to Soxhlet extraction and part of the extracts redissolved in dimethylsulfoxide (DMSO) for analyses of estrogenic activity by means of the yeast-based human estrogen receptor (hER) bioassay. A synthetic estrogen, 17-alpha-ethinylestradiol (EE2), was used as the reference estrogenic compound. Part of the extracts was analyzed for the 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs). Estrogenic compounds in the flue gas (wood) were as high as 234 +/- 25 ng m(-3) EE2 equivalent compared with 27 to 81 ng m(-3) EE2 equivalent in flue gas from combustion of barbecue charcoal. Concentrations of polycyclic aromatic hydrocarbons in both flue gas streams were in the range of 21000 +/- 2000 and 240 +/- 110 ng m(-3), respectively. In general, the concentrations of EE2 equivalent in the flue gas samples were at least a factor of 1000 lower than total PAH concentration. The EE2 levels were not related to the concentration of PAHs in any flue gas sample
Invasive Salmonellosis in Kilifi, Kenya.
BACKGROUND: Invasive salmonelloses are a major cause of morbidity and mortality in Africa, but the incidence and case fatality of each disease vary markedly by region. We aimed to describe the incidence, clinical characteristics, and antimicrobial susceptibility patterns of invasive salmonelloses among children and adults in Kilifi, Kenya. METHODS: We analyzed integrated clinical and laboratory records for patients presenting to the Kilifi County Hospital between 1998 and 2014. We calculated incidence, and summarized clinical features and multidrug resistance. RESULTS: Nontyphoidal Salmonella (NTS) accounted for 10.8% and 5.8% of bacteremia cases in children and adults, respectively, while Salmonella Typhi accounted for 0.5% and 2.1%, respectively. Among 351 NTS isolates serotyped, 160 (45.6%) were Salmonella Enteritidis and 152 (43.3%) were Salmonella Typhimurium. The incidence of NTS in children aged <5 years was 36.6 per 100 000 person-years, being highest in infants aged <7 days (174/100 000 person-years). The overall incidence of NTS in children varied markedly by location and declined significantly during the study period; the pattern of dominance of the NTS serotypes also shifted from Salmonella Enteritidis to Salmonella Typhimurium. Risk factors for invasive NTS disease were human immunodeficiency virus infection, malaria, and malnutrition; the case fatality ratio was 22.1% (71/321) in children aged <5 years and 36.7% (11/30) in adults. Multidrug resistance was present in 23.9% (84/351) of NTS isolates and 46.2% (12/26) of Salmonella Typhi isolates. CONCLUSIONS: In Kilifi, the incidence of invasive NTS was high, especially among newborn infants, but typhoid fever was uncommon. NTS remains an important cause of bacteremia in children <5 years of age
Risk of nontyphoidal Salmonella bacteraemia in African children is modified by STAT4
Nontyphoidal Salmonella (NTS) is a major cause of bacteraemia in Africa. The disease typically affects HIV-infected individuals and young children, causing substantial morbidity and mortality. Here we present a genome-wide association study (180 cases, 2677 controls) and replication analysis of NTS bacteraemia in Kenyan and Malawian children. We identify a locus in STAT4, rs13390936, associated with NTS bacteraemia. rs13390936 is a context-specific expression quantitative trait locus for STAT4 RNA expression, and individuals carrying the NTS-risk genotype demonstrate decreased interferon-gamma (IFN gamma) production in stimulated natural killer cells, and decreased circulating IFN gamma concentrations during acute NTS bacteraemia. The NTS-risk allele at rs13390936 is associated with protection against a range of autoimmune diseases. These data implicate interleukin-12-dependent IFN gamma-mediated immunity as a determinant of invasive NTS disease in African children, and highlight the shared genetic architecture of infectious and autoimmune disease.Peer reviewe
Population-Based Estimate of Melioidosis, Kenya.
Melioidosis is thought to be endemic, although underdiagnosed, in Africa. We identified 5 autochthonous cases of Burkholderia pseudomallei infection in a case series in Kenya. Incidence of B. pseudomallei bacteremia in Kenya's Kilifi County is low, at 1.5 cases per million person-years, but this result might be an underestimate
Age-dependent acquisition of IgG antibodies to Shigella serotypes—a retrospective analysis of seroprevalence in Kenyan children with implications for infant vaccination
BackgroundShigellosis mainly affects children under 5 years of age living in low- and middle-income countries, who are the target population for vaccination. There are, however, limited data available to define the appropriate timing for vaccine administration in this age group. Information on antibody responses following natural infection, proxy for exposure, could help guide vaccination strategies.MethodsWe undertook a retrospective analysis of antibodies to five of the most prevalent Shigella serotypes among children aged <5 years in Kenya. Serum samples from a cross-sectional serosurvey in three Kenyan sites (Nairobi, Siaya, and Kilifi) were analyzed by standardized ELISA to measure IgG against Shigella sonnei and Shigella flexneri 1b, 2a, 3a, and 6. We identified factors associated with seropositivity to each Shigella serotype, including seropositivity to other Shigella serotypes.ResultsA total of 474 samples, one for each participant, were analyzed: Nairobi (n = 169), Siaya (n = 185), and Kilifi (n = 120). The median age of the participants was 13.4 months (IQR 7.0–35.6), and the male:female ratio was 1:1. Geometric mean concentrations (GMCs) for each serotype increased with age, mostly in the second year of life. The overall seroprevalence of IgG antibodies increased with age except for S. flexneri 6 which was high across all age subgroups. In the second year of life, there was a statistically significant increase of antibody GMCs against all five serotypes (p = 0.01–0.0001) and a significant increase of seroprevalence for S. flexneri 2a (p = 0.006), S. flexneri 3a (p = 0.006), and S. sonnei (p = 0.05) compared with the second part of the first year of life. Among all possible pairwise comparisons of antibody seropositivity, there was a significant association between S. flexneri 1b and 2a (OR = 6.75, 95% CI 3–14, p < 0.001) and between S. flexneri 1b and 3a (OR = 23.85, 95% CI 11–54, p < 0.001).ConclusionChildren living in low- and middle-income settings such as Kenya are exposed to Shigella infection starting from the first year of life and acquire serotype-specific antibodies against multiple serotypes. The data from this study suggest that Shigella vaccination should be targeted to infants, ideally at 6 or at least 9 months of age, to ensure children are protected in the second year of life when exposure significantly increases
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