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PubMed1988

Epidemiology of antimicrobial resistant cholera in Kenya and East Africa.

Strains of Vibrio cholerae O1, El Tor resistant to multiple antimicrobial agents, were isolated in Kenya between 1982 and 1985. Strains of serotype Ogawa were resistant to tetracycline, ampicillin, and trimethoprim/sulfamethoxazole. Resistance was mediated in all instances by a plasmid ca 100 mD of incompatibility group C. Based on analysis of restriction endonuclease digests, all Ogawa isolates had an identical resistance plasmid. This plasmid differed from plasmids in resistant V. cholerae O1 strains isolated in Tanzania, Nigeria, and Bangladesh. On Southern blot analysis of restriction endonuclease digests of chromosomal DNA using DNA probes there were no apparent differences between Kenyan V. cholerae O1 strains isolated before and after emergence of antibiotic resistance; however, a majority of El Tor strains isolated in other geographic areas had the same Southern blot pattern. Our data document the apparent endemicity of multiply antimicrobial resistant V. cholerae O1 strains in Kenya, and the persistence of a single unique resistance plasmid among isolates of serotype Ogawa.

Africa, Eastern↗
PubMed1990

Plasmodium falciparum infection rates in Anopheles gambiae, An. arabiensis, and An. funestus in western Kenya.

Mosquitoes collected monthly for 1 year from human habitations in the Kisumu area of western Kenya were identified by morphological characters as Anopheles gambiae Giles sensu lato (An. gambiae s.l.) or An. funestus. Of the mosquitoes collected, 7,244 (67%) of the An. gambiae s.l. and 8,511 (87%) of the An. funestus were tested by enzyme-linked immunosorbent assay (ELISA) for the presence of Plasmodium falciparum circumsporozoite (CS) protein. ELISA positivity rates were 8.2% for An. gambiae s.l. and 6.1% for An. funestus. Both An. gambiae and An. arabiensis were detected among 432 ELISA-positive and 668 ELISA-negative An. gambiae s.l. identified to species with a ribosomal DNA probe. The species-specific infection rates were calculated to be 9.6% for An. gambiae and 0.4% for An. arabiensis. These results confirm that An. gambiae and An. funestus are the primary malaria vectors in western Kenya and that An. arabiensis is a relatively minor vector.

Animals↗
PubMed1991

Phlebotomus guggisbergi (Diptera: Psychodidae), a vector of Leishmania tropica in Kenya.

Sand flies were collected in light traps and on oiled papers at four active case sites of human cutaneous leishmaniasis due to Leishmania tropica at Muruku Sublocation, Laikipia District, Kenya. Nearly 5,200 females of five species, including Phlebotomus guggisbergi, were dissected and examined for flagellates. Of 3,867 P. guggisbergi females collected at a multiple case site, 168 (4.3%) harbored mature infections (to include metacyclic promastigotes) of flagellates morphologically identical to Leishmania, while all other flies were negative. Of the infected flies, 164 were collected in a cave near the patients' home, three from crevices on an escarpment immediately behind the house, and one from the bedroom of one of the patients. One hundred sixty-four of the isolates were successfully grown in Schneider's Drosophila medium and harvested for typing by cellulose-acetate electrophoresis. Isoenzyme profiles of the first 22 of these were compared with those of WHO reference strains and well characterized local strains using 12 enzyme loci. The isolates yielded isoenzyme migration patterns that were indistinguishable from those of two L. tropica reference strains and of six L. tropica patient isolates from the same locality. This is the first reported isolation of L. tropica from a sand fly in Kenya, the first reported isolation of Leishmania parasites from P. guggisbergi, and the first confirmed isolation of this Leishmania from a sand fly other than P. sergenti. The finding of such a large number of P. guggisbergi naturally harboring mature infections of L. tropica at an active case site of cutaneous leishmaniasis due to this agent strongly implicates this fly as a vector.

Animals↗
PubMed1996

The pattern of pediatric solid malignant tumors in western Kenya, east Africa, 1979-1994: an analysis based on histopathologic study.

This study analyzed histopathologic specimens of 600 pediatric solid malignant tumors seen during the period 1979-1994 at the histopathology laboratories of the Rift Valley Provincial General Hospital in Nakuru, the Nyanza Provincial General Hospital in Kisumu, and the Uasin Gishu Hospital in Eldoret in western Kenya. The crude incidence rate of each malignancy per 100,000 children per year was calculated. The patterns of malignancies were examined with a focus on tumor incidence, age, sex, geographic, and ethnic distribution to relate the tumors to putative environmental and genetic causative factors. The six common tumors were Burkitt's lymphoma (33.5%), non-Hodgkin's lymphoma (21.8%), retinoblastoma (11.5%), Kaposi's sarcoma (6.1%), nephroblastoma (4.5%), and Hodgkin's disease (4.1%). Significantly high crude incidence rates for lymphomas and Kaposi's sarcoma showed a characteristic ethnogeographic distribution. The majority of the tumors were found concentrated around Lake Victoria and showed decreasing occurrence as one moved towards the semi-arid and highland areas. We concluded that environmental factors seem to play a major role in childhood tumors in western Kenya.

Adolescent↗
PubMed1997

Limited spatial clustering of individual Plasmodium falciparum alleles in field isolates from coastal Kenya.

We describe Plasmodium falciparum genetic diversity in coastal Kenya, typing S-antigen and the merozoite surface proteins 1 and 2 (MSP-1 and MSP-2) in field isolates by the polymerase chain reaction (PCR). Malaria in coastal Kenya is characterized by low seasonal transmission, and a relatively high incidence of severe disease, which tends to occur in time-space clusters. We chose the highly polymorphic S-antigen as a marker for localized parasite diversity because it has been shown to vary in serotype prevalence in time and space. A total of 261 children (up to nine years of age) in two neighboring locations with different transmission rates were sampled for blood-stage parasites in cross-sectional surveys before and after the main transmission period in 1991, and also in a concomitant one-year longitudinal survey tracing clinical infections. Six major sequence types of S-antigen were identified, which were subdivided into 70 alleles; however, only 50% of isolates were typeable. The S-antigen sequence types varied qualitatively between locations, over time, and between asymptomatic and clinical disease infections, but not between different age groups. The MSP-1 and MSP-2 sequence type prevalences, in contrast, did not differ in any of these comparisons. We describe the use of the Mantel test for assessing clustering of individual parasite alleles at the household level, and demonstrate low-level clustering of MSP-1 and MSP-2 alleles and S-antigen sequence types, at the end of a long period of low transmission.

Age Factors↗
PubMed1998

First recorded outbreak of yellow fever in Kenya, 1992-1993. II. Entomologic investigations.

The first recorded outbreak of yellow fever in Kenya occurred from mid-1992 through March 1993 in the south Kerio Valley, Rift Valley Province. We conducted entomologic studies in February-March 1993 to identify the likely vectors and determine the potential for transmission in the surrounding rural and urban areas. Mosquitoes were collected by landing capture and processed for virus isolation. Container surveys were conducted around human habitation. Transmission was mainly in woodland of varying density, at altitudes of 1,300-1,800 m. The abundance of Aedes africanus in this biotope, and two isolations of virus from pools of this species, suggest that it was the principal vector in the main period of the outbreak. A third isolate was made from a pool of Ae. keniensis, a little-known species that was collected in the same biotope. Other known yellow fever vectors that were collected in the arid parts of the valley may have been involved at an earlier stage of the epidemic. Vervet monkeys and baboons were present in the outbreak area. Peridomestic mosquito species were absent but abundant at urban sites outside the outbreak area. The entomologic and epidemiologic evidence indicate that this was a sylvatic outbreak in which human cases were directly linked to the epizootic and were independent of other human cases. The region of the Kerio Valley is probably subject to recurrent wandering epizootics of yellow fever, although previous episodes of scattered human infection have gone unrecorded. The risk that the disease could emerge as an urban problem in Kenya should not be ignored.

Adolescent↗
PubMed1999

Vector-related case-control study of severe malaria in Kilifi District, Kenya.

A case-control study examined vector-related and environmental parameters associated with severe malaria in Kilifi District along the coast of Kenya. Over an 11-month period, 119 children identified with severe malaria infections at the Kilifi District Hospital were matched by age with control children who reported to the outpatient clinic with nonsevere infections. Intensive mosquito sampling was done in each of the case-control houses over a four-day period, beginning within a week of index case admission. A total of 109 environmental, demographic, behavioral, and animal husbandry variables were characterized for each household. Vector species (Anopheles gambiae s.l. and An. funestus) were detected in 40.1% and 36.1% of case and control houses, respectively. The relative abundance of vectors in individual houses was stable over the two-week resampling periods (r = 0.9). Both the overall abundance of anopheline mosquitoes (odds ratio [OR] = 1.5) and P. falciparum sporozoite rates (OR = 1.5) were not significantly different between case and control houses. In a matched analysis, 11 of 109 house variables associated significantly with severe malaria were also associated with vector abundance, as determined by chi-square linear trend analysis. Under conditions of year-round, low-level transmission on the coast of Kenya, the risk of severe disease in children is multifactorial and not governed strictly by transmission intensity or environmental heterogeneity affecting vector abundance and distributions. This suggests that current interventions that appear to be achievable only in areas where transmission is already low to moderate should be appropriate. However, such interventions should be monitored so that inappropriate and possibly disastrous control activities can be avoided in Africa.

Animals↗
PubMed1999

Impact of the crayfish Procambarus clarkii on Schistosoma haematobium transmission in Kenya.

The Louisiana red swamp crayfish, Procambarus clarkii, which was introduced into east Africa in the 1950s or 1960s, has since widely dispersed. Previous work by our group has shown that P. clarkii can reduce populations of the molluscan intermediate hosts of human schistosomes through predatory and competitive interactions. Here, we investigate whether crayfish can reduce populations of Bulinus africanus and consequently, Schistosoma haematobium prevalence in school children. Children from 6 primary schools in the Machakos and Kitui Districts of Kenya were selected for study. Schools were divided into 3 experimental-control pairs. At experimental schools, crayfish were introduced into nearby aquatic habitats harboring Bulinus africanus snails and serving as S. haematobium transmission sites. Snail habitats near control schools did not receive crayfish. Six months after crayfish introduction, all infected children were treated with praziquantel. Children were then monitored quarterly for 2 years, at which time infection and reinfection rates were compared statistically between the paired schools. In one such pair, crayfish failed to establish, resulting in neither snail control nor a reduction in transmission. At the second pair of schools, the numbers of snails were decreased by the presence of crayfish, but a clear difference in infection rates in children could not be detected, primarily because drought conditions kept overall transmission rates low. At the third school pair, crayfish established well in experimental habitats, snail numbers decreased precipitously, and children at the experimental school were significantly less likely to acquire S. haematobium infections than children at the control school. Our results indicate that under certain environmental circumstances, P. clarkii exerts a significant impact on the transmission of human schistosomiasis in Kenya. Important questions remain regarding the impact of P. clarkii on Kenyan freshwater ecosystems, not the least of which is its potential to significantly influence the epidemiology of schistosomiasis in east Africa.

Adolescent↗
PubMed2000

First field evidence for natural vertical transmission of West Nile virus in Culex univittatus complex mosquitoes from Rift Valley province, Kenya.

West Nile virus is a mosquito borne flavivirus endemic over a large geographic area including Africa, Asia, and the Middle East. Although the virus generally causes a mild, self-limiting febrile illness in humans, it has sporadically caused central nervous system infections during epidemics. An isolate of West Nile virus was obtained from a pool of four male Culex univittatus complex mosquitoes while we were conducting an investigation of Rift Valley fever along the Kenya-Uganda border in February-March 1998. This represents the first field isolation of West Nile virus from male mosquitoes and strongly suggests that vertical transmission of the virus occurs in the primary maintenance mosquito vector in Kenya. A phylogenetic analysis of the complete amino acid sequence of the viral envelope glycoprotein demonstrated a sister relationship with a Culex pipiens mosquito isolate from Romania made in 1996. This unexpected finding probably reflects the role of migratory birds in disseminating West Nile virus between Africa and Europe.

Amino Acid Sequence↗
PubMedDate not supplied

All-cause mortality among young children in western Kenya. VI: the Asembo Bay Cohort Project.

Although all-cause mortality has been used as an indicator of the health status of childhood populations, such data are sparse for most rural areas of sub-Saharan Africa, particularly community-based estimates of infant mortality rates. The longitudinal follow-up of more than 1,500 children enrolled at birth into the Asembo Bay Cohort Project (ABCP) in western Kenya between 1992 and 1996 has provided a fixed birth cohort for estimating all-cause mortality over the first 5 yr of life. We surveyed mothers and guardians of cohort children in early 1999 to determine survival status. A total of 1,260 households were surveyed to determine the survival status of 1,556 live births (99.2% of original cohort, n = 1,570). Most mothers (66%) still resided but 27.5% had migrated, and 5.5% had died. In early 1999, the overall cumulative incidence of all-cause mortality for the entire 1992-1996 birth cohort was 26.5% (95% confidence interval, 24.1-28.9%). Neonatal and infant mortality were 32 and 176 per 1,000 live births, respectively. These community-based estimates of mortality in the ABCP area are substantially higher than for Kenya overall (nationally, infant mortality is 75 per 1,000 live births). The results provide a baseline description of all-cause mortality among children in an area with intense Plasmodium falciparum transmission and will be useful in future efforts to monitor changes in death rates attributable to control programs for specific diseases (e.g., malaria and HIV/AIDS) in Africa.

Adolescent↗
PubMed2003

Spotted fever group rickettsiae in ticks from the Masai Mara region of Kenya.

We have identified for the first time Rickettsia africae, and the ticks that harbored them, in Kenya. A total of 5,325 ticks were collected from vegetation, livestock, and wild animals during two field trips to southwestern Kenya. Most were immature forms (85.2%) belonging to the genera Amblyomma or Rhipicephalus. The adults also included representatives from the genus Boophilus. Ticks were assessed for rickettsial DNA by a polymerase chain reaction (PCR) using primers for the spotted fever group (SFG)-specific rickettsial outer membrane protein A (rompA) gene, and positive amplicons were sequenced. While none of the immature ticks tested positive by PCR, 15.8% of the adult Amblyomma variegatum and less than 1% of the Rhipicephalus spp. were SFG positive. Sequences of amplified products were identified as R. africae. These findings extend the known range of R. africae.

Animals↗
PubMed2000

Epidemiology of single and multiple species of helminth infections among school children in Busia District, Kenya.

OBJECTIVE: To describe the patterns of single and multiple helminth infection in school children from Busia District, Kenya. DESIGN: A cross-sectional school survey using a randomly selected sample, forming part of an evaluation study of an ongoing deworming project. SETTING: Budalangi and Funyula divisions of Busia District, Western Province, Kenya. SUBJECTS: One thousand seven hundred and thirty eight school children aged 8-20 years randomly selected from those enrolled in standards 3-8 in 25 randomly selected primary schools. RESULTS: Overall, 91.7% of children were infected with either hookworm, Ascaris lumbricoides, Trichuris trichiura or Schistosoma mansoni. Infection prevalence of each species varied considerably among schools, being most marked for S. mansoni, where prevalence was highest in lakeshore schools. Children were typically infected with two or more species of helminth. Infection intensity of each geohelminth species was higher in school children infected with multiple species than in school children with single species infections, and intensity increased with the number of concurrent infections. CONCLUSION: Helminth infections are exceptionally common among school children in Busia district, thus confirming the good sense of the school-based approach adopted by the control programme. The study also shows that there is an association between concurrent infection and the intensity of infection, which may have consequences for nutritional and educational status.

Adolescent↗
PubMed2000

Experience with IUCD insertion outside of menses in Kenya.

OBJECTIVE: To determine if women receiving intrauterine devices (IUCDs) outside of menses have an acceptable rate of insertion problems and subsequent IUCD-related complications. DESIGN: Cross-sectional and prospective cohort study of insertions at times other than during menses. SETTING: The study was carried out in two government family planning (FP) clinics in Nairobi, Kenya. SUBJECTS: After appropriate pre-test and post-test HIV counselling, 1686 women requesting IUCDs at two FP clinics between 1994 and 1995 in Nairobi were enrolled at baseline into a study examining the effect of human immuno-deficiency virus (HIV) infection on IUCD-related complications. Six hundred and forty nine women (156 HIV-infected and 493 HIV-uninfected) were selected for the four month follow up study. They were classified according to their menstrual cycle status at time of IUCD insertion. MAIN OUTCOME MEASURES: Problems at the time of insertion (pain, bleeding, immediate expulsion) and IUCD-related complications through four months. RESULTS: Rates of immediate insertion problems were low in the women who had insertions during menses (7.0%), outside of menses (4.0%) or had oligomenorrhea/amenorrhea (2.6%). The adjusted odds ratios for IUCD insertion problems outside of menses and in oligomenorrhea/amenorrhea (versus women with insertion during menses) were 0.54 (95 % CI 0.18-1.59) and 0.39 (95% CI 0.12-1.29) respectively. IUCD-related complications were higher in the oligomenorrhea/amenorrhea (11.5%) or insertion outside of menses (6.9%), than the within menses (4.3%) groups. However, the differences were not statistically significant. Adjusted odds ratios for IUCD outside of menses and oligomenorrhoea/amenorrhea groups were 1.65 (95% CI 0.21-12.91) and 2.72 (95% CI 0.34-21.71) respectively. CONCLUSION: The results confirm that the IUCD can be safely inserted outside of menses with minimal insertion difficulties and subsequent complications. Availability of IUCDs outside of menses may enhance IUCD acceptance in Kenya and create better opportunity for visual screening of the cervix for sexually transmitted infections.

Adult↗
PubMed2001

Foodborne diseases in Kenya.

OBJECTIVES: To determine the occurrence of foodborne disease outbreaks in Kenya and the efforts employed to combat them. DESIGN: Cross-sectional survey. SETTING: Forty two districts in Kenya between 1970 and 1993. STUDY SUBJECTS: Foodborne disease outbreak episodes due to Staphylococcus aureus, Clostridium perfringens, Clostridium botulinum, Bacillus cereus, Escherichia coli, Campylobacter jejuni, Yersinia enterocolitica, Listera monocytogenes, chemicals, aflatoxin, plant and animal poisons. OUTCOME MEASURES: Number and aetiological causes of foodborne disease outbreaks reported in the study period. RESULTS: Thirty seven food poisoning outbreaks were reported to the Ministry of Health from various parts of the country in the study period 1970 to 1993, and only 13 of these involving a total of 926 people were confirmed to be due to particular aetiological agents. Foods that were involved included milk and milk products, meat and meat products, maize flour, bread, scones and other wheat products, vegetables and lemon pie pudding. A high number of food poisoning cases were treated as outpatients in various health facilities. CONCLUSION: Under-reporting, inadequate investigation of outbreaks and inadequate diagnostic facilities suggest that foodborne disease outbreaks are more than is recorded by the Ministry of Health.

Animals↗
PubMed2001

Health problems of street children in Eldoret, Kenya.

BACKGROUND: The street children phenomenon is an increasing problem in most cosmopolitan cities of the world including Eldoret, which is a fast growing town. With the growth of the town so is the increasing number of street children. It is therefore important to have baseline data on their health problems. OBJECTIVE: To determine the health problems of street children in Eldoret. DESIGN: A prospective and descriptive study. SETTING: Eldoret Town, Kenya. SUBJECTS: Eldoret street children aged 5-21 years. Type 1 street children were the "on" the street children who spent most of their time on the streets but went home in the evenings, type 2 were the "of" the street children who spent all their time in the streets and had severed their links with their families and did not have a home to go to, type 3 were abandoned children staying in a shelter and type 4 were normal primary school children. RESULTS: One hundred and ninety one children were studied. There were 38, 47, 56 and 50 types 1, 2, 3 and 4 children, respectively. The most common symptom was cough (28.9%) while frequent diagnosis was upper respiratory tract infection (URTI) (12.1%) followed by skin disease (50.9%) as the leading disease category. The common drug of addiction was cigarette (37.6%) and none of the school children was taking any drug of addiction. The prevalence of disease was 467 per 1000 children. Type 2 street children had the highest prevalence of disease (833 per 1000 children). Shelter children had the least disease prevalence (474 per 1000). Factors determining prevalence of disease were the same as in normal children. The malnutrition rate was high with 31.1% and 41.9% of the children being stunted and underweight, respectively. Type 3 children had the highest rate of malnutrition with 51.8% and 64.3% being stunted and underweight. CONCLUSION: Street children have a high incidence of childhood diseases. Factors determining occurrence of disease among street children are as in normal children. Respiratory and skin diseases were the leading causes of morbidity. Drug abuse was rampant among the street children but none of the school children abused any drug. Sexually transmitted infections were not prevalent. Most of the shelter children were malnourished. RECOMMENDATIONS: The government of Kenya should provide free health care for street children in public hospitals. Further studies should be carried out on the prevalence of sexually transmitted diseases based on laboratory testing and on the causes of the injuries suffered by the street children. The reasons for the poor nutritional status of the shelter children should be analysed and appropriate measures taken.

Adolescent↗
PubMed2003

Pneumocystis carinii pneumonia in HIV/AIDS patients at an urban district hospital in Kenya.

BACKGROUND: Pneumocystis carinii pneumonia has generally been regarded to be an uncommon opportunistic infection in HIV infected individuals in sub-Saharan Africa. The reason for this has not been clear but postulates included a lack of suitable pathogenic types in the African environment, diagnostic difficulties and the more commonly held belief that African HIV infected individuals were dying early from common non-opportunistic pathogens before severe degrees of immunosuppression occured. Recently a trend has emerged at the Mbagathi district hospital whereby an increasing number of HIV infected patients are empirically treated for Pneumocystis carinii pneumonia (PCP) based on clinical and radiological features. OBJECTIVE: To determine the prevalence of PCP and clinical outcomes of HIV infected patients presenting at the Mbagathi District Hospital, Nairobi with the presumptive diagnosis of PCP. SETTING: Mbagathi District Hospital, a 169-bed public hospital in Nairobi, Kenya. METHODS: Patients presenting with a sub-acute onset of cough and dyspnoea were eligible for the study if they were found to have bilateral pulmonary shadows and had negative sputum smears for AFBS. Consenting patients who had no contraindication to fiberoptic bronchoscopy had a clinical evaluation which was followed with a fiberoptic bronchoscopy procedure where bronchoalveolar lavage fluid (BALF) was obtained. BALF was examined for cysts of P. carinii using toluidine blue stain and immunofluorescent antibody test (IFAT). BALF was also processed for fungi, bacteria and mycobacteria using routine procedures. Standard treatment with high dose cotrimoxazole was offered to all patients who were then followed up until discharge from hospital or death whichever came first. RESULTS: Between June 1999 and August 2000 a total of 63 patients were referred for bronchoscopy. Of these four declined to undergo the fiberoptic bronchoscopy procedure, four died before the procedure could be done, one was judged too sick to undergo the procedure and three had been on cotrimoxazole for longer than five days. Thus 51 patients underwent bronchoscopy. Pneumocystis carinii stain was positive in 19 (37.2%) while death occured in 16 (31.4%) of the 51 patients. There were more deaths in those without PCP but this difference was not statistically significant (odds ratio 0.68 (95% CI 0.35-1.32; P=0.2). CONCLUSION: PCP was found to be common in HIV infected patients presenting with clinical and radiological features of the disease. The mortality rate for patients with a presumptive diagnosis of PCP is high. This study suggests that cotrimoxazole preventive therapy may be a useful intervention in symptomatic HIV infected patients in Kenya for the prevention of PCP and may avert deaths from this disease.

AIDS-Related Opportunistic Infections↗
PubMed2003

Socio-demographic factors of pupils who use tobacco in randomly-selected primary schools in Nairobi province, Kenya.

OBJECTIVE: To report the prevalence and socio-economic correlates of tobacco use among primary school pupils in Nairobi, Kenya. DESIGN: Cross-sectional school-based survey. SETTING: Ten primary schools in Nairobi, Kenya. SUBJECTS: A questionnaire was administered to 1198 primary school pupils aged 12 to 17 years and 1130 (response rate 94.3%) students responded under supervision in the classroom. RESULTS: A total of 31% (95% CI 27.5-34.5) had experimented with smoking, 9% (95% CI 7.1-11.5) with smokeless tobacco and 55% (95% CI 50.7-59.6) reported having friends who smoked. The rates of lifetime smoking were statistically significantly higher in urban than in suburban students (33% versus 25%, p<0.05), whereas a higher proportion of suburban residents reported lifetime use of smokeless tobacco (8 % versus 12 %, p<0.05). Among urban as well as suburban students, 15 years and above were significantly more likely than their counterparts aged 14 years and below to report lifetime smoking, lifetime use of smokeless tobacco, fathers' use of tobacco, and friend's tobacco use. The adjusted odds ratios, OR, and 95% confidence intervals, 95% CI, for students ever smoking were 2.2 (95% CI 1.3-1.8), 2.4 (95 % CI 1.6-3.7), 1.8 (95 % CI 1.1-3.2 and 2.6 (95 % CI 1.7-4.1) for place of residence, gender, age and friend's use of tobacco. CONCLUSION: Generally, the proportions of primary pupils using different forms of tobacco were low in Nairobi province, although the proportion of pupils who had smoked at least once in their lifetime amounted to 31%. Since primary school pupils live in an environment that makes them susceptible to smoking, preventive programmes should be introduced to avoid the development of nicotine addiction and regular smoking.

Adolescent↗
PubMed2003

Epidemiology of highland malaria in western Kenya.

OBJECTIVES: To investigate the epidemiology of falciparum malaria in workers from a highland tea plantation in western Kenya with very seasonally limited malaria transmission to determine what factors are associated with increased risk of malaria transmission in the Kenyan highlands. DESIGN: A cross-sectional study with rolling, random subject enrollment from April 1998 through October 1999. SETTING: Highland tea plantation located at 0 degrees 22' south and 35' 17' east in the Rift Valley highlands of western Kenya, an area with seasonally limited malaria transmission. SUBJECTS: The data for the study were obtained from enrollment of outpatients from the healthcare system of a major tea company, which has 18 estates with 22,000 workers and approximately 50,000 persons eligible for health care. Of the 2796 patients evaluated during the study period, 798 cases of malaria were confirmed by positive peripheral blood smear; 1998 smear-negative patients were pressured to be non-infected and served as controls (Ratio: 2.52: 1). INTERVENTIONS: Tea estate workers do not receive malaria chemoprophylaxis, but were given easily available free treatment for any symptomatic infections. MAIN OUTCOME MEASURES: Smear-positive cases were compared with smear-negative patients for multiple demographic and disease variables, including sex, age, travel history, ethnic origin, home district transmission risk index and length of residence. Disease characteristics, including parasite types, counts and clinical symptoms, and treatments administered were described. RESULTS: Malaria was predominantly P. falciparum (>99%); asexual parasite counts ranged from 1-10,440 per mm3, with a mean of 803.6 (95% confidence interval: 695.2, 912.0). Gametocytemia was present in 7.5% of smear-positive malaria cases, but was rare in the absence of blood asexual forms (0.5%). Prior use of a variety of antimalarial drugs was extremely common and negatively predictive of parasitemia in patients presenting for clinical treatment (Pearson Chi-square 50.81, p < 0.001), as was a subjective history of previous malaria infection in the past year (F = 26.65, 14 df, p < 0.001; univariate ANOVA). Amodiaquine was the most commonly used drug to treat cases of either smear-proven or clinically suspected malaria, accounting for 56% of therapy; pyrimethamine/sulfadoxine was used to treat 27%, artemesinin 8% and chloroquine was administered to only 3%, while combination therapy was used in 5% of cases, and only a single treatment (0.1 %) was recorded using quinine. Subjects with a prior history of treatment for malaria were statistically less likely to be infected again (Pearson Chi-square 50.81, p < 0.001). Presenting with symptoms suggestive of malaria was statistically associated with parasitemia, particularly fever, headache and dizziness, (p <0.001 for all, univariate ANOVA), but in general, clinical symptoms were not an effective discriminator of malarial disease. Ethnic group predicted malaria infection with groups traditionally from the Lake Victoria lowland regions having a greater prevalence of parasitemia (F = 2.04, 4. df, p = 0.002, univariate ANOVA). Parasitemia was significantly associated with age less than ten years (Pearson Chi-Square 145.99, p < 0.001), with a history of travel more than twenty kilometers from site within six weeks (Pearson Chi-square 58.28, p < 0.001) and with time since arrival on the plantation of one year or less (Pearson Chi-square 185.12, p <0.001) CONCLUSION: Lower infection rates in persons with a history of prior infection implies a protective effect; the predilection of malaria for young and immunologically naive victims was confirmed. The proclivity in some ethnic groups for travel to holoendemic areas also accounts for the strong associations between recent travel, lowland ethnic group and infection. These findings taken together suggest that importation of malaria to the highlands, as well as travel away from the highlands, are important sources of new infections among persons living and working there.

Adolescent↗