The health workers for change impact study in Kenya.

This paper reports the detailed results of a study of the impact of the Health Workers for Change (HWFC) workshop series on clients' perceptions of health services, relationships within the health centre and relations between the health facility and the district health system. The study was carried out in three stages: baseline, intervention and evaluation over a period of 20 months. Data, both qualitative and quantitative, were collected at three levels: client, facility and system. Results indicate that relations between health workers and clients improved a great deal after the intervention while those between the facility and the system remained to a large extent unchanged. The paper concludes that, with external support and help, especially from the health system level, health workers can work towards improving health services and their job satisfaction, which can lead to better health worker-client relations.

Prevalence and familial aggregation of schistosomal liver morbidity in Kenya: evaluation by new ultrasound criteria.

Severe periportal fibrosis is not an inevitable consequence of infection with Schistosoma mansoni. Genetic predisposition may be a deciding factor in the development of disease. To assess the contribution of genetic factors in the severity of hepatic fibrosis, the degree of familial aggregation was determined in a Kenyan population. Schistosomal fibrosis was identified with hepatic ultrasound and newly proposed World Health Organization criteria, which include both qualitative and quantitative observations. These 2 aspects of the criteria correlated well with one another. The peak prevalence of ultrasound proven fibrosis trailed 5-10 years behind peak prevalence of infection and declined sharply after age 50 years. This pattern was consistent with either resolution of severe fibrosis over 10-20 years or early death of those severely affected. Genetic predisposition appears to be a weak factor in the development of severe disease in this population, since no household or familial aggregation could be identified.

Host-parasite relationships in infections with two Kenyan isolates of Schistosoma mansoni in NMRI mice.

To relate the marked differences observed in morbidity due to Schistosoma mansoni infection in the Kangundo and Kibwezi areas of Machakos District, Kenya with possible parasite-related differences in pathobiological characteristics, a quantitative comparison of the host-parasite relationship in infections in NMRI mice with S. mansoni isolates from the 2 areas was conducted. One hundred and 20 cercariae were used per mouse, and necropsy took place between 35 and 94 days following infection. Parameters assessed comprised worm establishment, tissue egg counts, fecal egg excretion, egg production/worm pair, and weights of liver and spleen. Central findings included a higher worm establishment and a lower egg production/worm pair in Kangundo infections than in Kibwezi infections, comparable total tissue schistosome egg counts, and a higher liver/intestinal tissue schistosome egg ratio in Kibwezi infected mice than in the Kangundo infected mice. In addition, a much higher fecal egg excretion, expressed as eggs/g feces and eggs/g feces/worm pair, was observed in mice infected with the Kangundo isolate of S. munsoni than in mice infected with the isolate from Kibwezi. Although possible limitations in the use of mouse models need be realized, the results provide some support to the hypothesis that parasite-related differences in pathobiological characteristics may at least contribute to the marked difference observed in S. mansoni-induced morbidity between the Kangundo and Kibwezi areas.

Spatial patterns of human water contact and Schistosoma mansoni transmission and infection in four rural areas in Machakos District, Kenya.

This paper presents the results of microgeographical studies of human water contact behavior and Schistosoma mansoni transmission levels and intensity of infection in four rural areas in Machakos District, Kenya. The relationship between intensity of infection (geometric mean egg counts) in 3502 persons aggregated in 120 household clusters and eight independent variables was investigated using straight and stepwise linear regression and mapping techniques. Results indicate that the two water contact variables, mean frequency per person and mean duration per person, as well as mean number of sites used per person, a transmission index and mean distance to the most frequently used site were the strongest predictors of geometric mean egg counts. All three distance variables were usually negatively associated with infection although intensity of infection and water contact declined relatively slowly with distance from the streams. This pattern appears to be owing to a combination of the relatively short distances, a general lack of safe alternative water sources and the use of more distant water contact sites both inside and outside the study area during periods of drought. The study of snail-to-man transmission identified number of infected snails as the major transmission variable and number of contacts as the major predictor variable. Mapping of total egg counts at the household cluster level and total number of infected snails revealed spatial association with transmission sites. All results varied considerably between study areas, owing to differences in exposure levels, transmission patterns and environmental factors. Findings are discussed in relation to the epidemiology and control of schistosomiasis and suggestions are made for further spatial studies.

Quality control of Kato slide counts for Schistosoma mansoni: a review of 12 years' experience in Kenya.

A total of 19 annual or biannual audits were performed over a 12-year period by an independent microscopist on randomized subsamples of Kato slides examined for Schistosoma mansoni eggs by Kenyan microscopists from the Division of Vector-borne Diseases (DVBD). The recounts were invariably lower than the originals owing to some deterioration of the preparations between counts, but the two were strongly correlated: significant regressions of recounts on counts taking up 80-90% of the observed variance. Observer bias differed significantly between microscopists but remained stable over time, whereas repeatability of recounts on counts dropped slightly in periods of maximum work load but did not vary systematically with time. Approximately 7% of the counts and recounts disagreed on the presence or absence of eggs, but less than a third of these were negatives that were found positive on recount. False negatives dropped to 1.3% if duplicate counts were considered. The performance of the Kenyan microscopists was remarkably high and consistent throughout the 12-year period. This form of quality control is suitable for projects where limited funds preclude full-time supervisors using more sophisticated systems.

PIP: When Kato slides are stored properly, the number of Schistosoma mansoni eggs in fecal smears remains countable for many months after preparation--a feature facilitating quality control studies in parasite control programs with limited resources. The present study compared egg recounts performed by independent microscopists in a total of 10,113 slides obtained in 19 annual or biannual audits with the original counts made by Division of Vector-borne Diseases (DVBD) microscopists in Kenya's Machakos and Makueni Districts in 1984-96. Recounts were performed 1-18 months after initial slide preparation. The overall proportion of discrepant counts in the 12-year study period was 6.83%. The majority of discrepant counts involved light infestations (50 eggs/g). At each audit, more slides were recorded as positive by DVBD microscopists and negative by the auditor than were recorded as negative by the DVBD and positive by the auditor. This trend is presumed to reflect Kato slide deterioration--especially a drying out before storage in hot, dry weather--between the initial count and the audit. Mean DVBD egg counts declined steadily between audits 10 (1989) and 19 (1996) in tandem with intensified treatment campaigns in the area. These findings confirm the suitability of this technique for quality control in programs with limited funds.

Water contact observations in Kenyan communities endemic for schistosomiasis: methodology and patterns of behaviour.

A descriptive analysis of observed water contact activities in seven Kenyan (Akamba) communities is presented. The patterns of contact with time of day, month of year, type of activity, degree of immersion, use of soap, use of 'kithima' and day of week are all considered, with particular attention given to how these vary with age and sex. It is noted that (a) patterns of contact vary dramatically between these culturally rather similar communities, (b) contact usually peaks in the second decade of life, (c) generally females, especially young women, spend more time at the water than males and (d) simple (unweighted) total observed duration of contact gives a relatively inflated estimate of exposure in adults, especially young women. The methodology of observation and data handling is described in some detail.

Schistosomiasis mansoni in Kenya: relationship between infection and anaemia in schoolchildren at the community level.

Haematological surveys were carried out in 3 schools in 2 areas where Schistosoma mansoni is endemic in Machakos District, Kenya, before and after a treatment campaign using praziquantel. Earlier clinical impressions of differences in the levels of anaemia between the 2 areas were not confirmed. Although individual haemoglobin levels and haematocrits often fell below international norms, significant anaemia with abnormal red blood cell morphology was rare (< 5%), but varied between schools. Altitude could have accounted for some of these differences, but other factors, including diet and parasitism, were involved. Anaemia was associated with splenomegaly and, to a lesser extent, hepatosplenomegaly. Epidemic malaria (mainly Plasmodium falciparum) appeared to be the main cause of parasite-induced anaemia. There was no significant association with the scarce hookworm infections (mainly Necator americanus); nor did the much commoner S. mansoni cause severe anaemia at the community level, but haemoglobin levels dropped as its intensity increased. Treatment with praziquantel eliminated this trend except in a few subjects with splenomegaly alone (probably due to malaria) or with schistosomal hepatosplenic disease. Possible pathogenic mechanisms are reviewed, including the consumption of red blood cells by adult schistosomes as a possible cause of anaemia.

Polyparasitism in two rural communities with endemic Schistosoma mansoni infection in Machakos District, Kenya.

Formol-ether concentration supplemented by fresh saline smears was used to study intestinal parasites in two communities, Miu and Kitengei, in Machakos District, Kenya. These communities differed markedly in schistosome associated morbidity, in spite of similar prevalence and intensities of infection as revealed by Kato examination, Seven helminth and nine protozoan species were detected among 1011 samples examined. More than 60% of the subjects were infected with more than one parasite: one had nine. Age-prevalence curves were typical for the different species, and overall prevalence of some protozoa, including Entamoeba spp. and Blastocystis hominis, exceeded that of the commonest helminth, Schistosoma mansoni. However, the observed prevalence of S. mansoni was barely 40% of that detected by Kato examinations. Strong associations were found between some pairs of protozoan species, but not with or among the helminths. The differences in the abundance and age-specific distribution of the other intestinal parasites at Miu and Kitengei were so small that it is unlikely that interactions between them and S. mansoni would account for the differences in schistosomal morbidity.

Observations on the effects of different chemotherapy strategies on the transmission of Schistosoma mansoni in Machakos District, Kenya, measured by long-term snail sampling and cercariometry.

Transmission of Schistosoma mansoni was monitored by routine snail sampling for Biomphalaria pfeifferi and by supplementary cercariometric measurements in 4 neighbouring study areas in Machakos District, Kenya. After 1 year, extensive, population-based chemotherapy with a single dose of praziquantel was given in 3 areas, but only minimal treatment in the fourth. In the year preceding treatment, seasonal transmission of S. mansoni and other non-human trematodes occurred in all 4 areas, despite some ecological differences and the effects of earlier treatment campaigns in 1 of the study areas. After treatment of all infected subjects in one area in which there had been earlier chemotherapy campaigns, S. mansoni transmission remained very low. It was reduced for at least 2 years after chemotherapy targeted at either all heavily infected subjects or all infected school children, but it was unaffected in an area where treatment was restricted to those few very heavily infected cases at risk of developing disease. Nowhere was transmission entirely eliminated by chemotherapy and that of non-human trematodes continued unabated. The snail data correspond well with the human, parasitological data. Targeting school children was as effective as more extensive campaigns, but chemotherapy alone never stopped S. mansoni transmission: reinfection was inevitable, at rates determined by ecological factors affecting snail populations.

Chemotherapy-based control of schistosomiasis haematobia. 3. Snail studies monitoring the effect of chemotherapy on transmission in the Msambweni area, Kenya.

Regular snail sampling was performed at 40 sites, representing the principal snail habitats, during a 4 year chemotherapy programme targetted at school-children in the Msambweni area of the coastal plain of Kenya. Populations of Bulinus africanus group snails, primarily from pools, showed seasonal variations, dropping when sites dried out and rising when they were refilled by the rains. Transmission, judged by the recovery of snails shedding typical fucocercous cercariae, continued throughout the treatment period at very low levels (less than 1% of the snails collected were infected) with peaks in October/November and in January/February after seasonal rains. Spatially, most infected snails were recovered from 2 large pools near the sea, close to the school that responded least well to the initial chemotherapy programme. Later, infected snails were found sporadically in inland pools, rice fields and temporary streams near another school where there was evidence of substantial reinfection as the study progressed. The snail findings are consistent with a reduction but not elimination of transmission associated with the chemotherapy programme.

Effect of mass chemotherapy and piped water on numbers of Schistosoma haematobium and prevalence in Bulinus globosus in Kwale, Kenya.

From June 1982 to May 1986 in a small village in Kwale, Kenya, we studied seasonal fluctuations in populations of Bulinus globosus, prevalence of Schistosoma haematobium infection in this snail, and effects of chemotherapy and piped water supply on infection rate of snails. In the perennially-flowing Pemba River, relatively small numbers of snails were collected; they were found only during the hot dry season (December to March). In a tributary stream, the Kadingo River, whose flow ceased at the end of both the cool and hot dry seasons, snail numbers peaked at the end of the cool dry season (October to November) and at the beginning of the hot dry season (January). Large numbers of infected snails were found in the Kadingo River from November to January (short rainy season and beginning of dry season). Selective mass chemotherapy with metrifonate and provision of piped water were begun in February and March 1984. These control measures achieved a significant reduction in the infection rate of snails (P less than 0.001); the annual infection rate for the 2 years before treatment was 9.3% and 13.1%, and for the 2 years after treatment was 3.5% and 3.4%.

Preliminary evaluation of some wild and cultivated plants for snail control in Machakos District, Kenya.

Fifty local medicinal, agricultural and wild growing deciduous plants, representing 49 species, 46 genera and 22 families, were screened as water extracts at 1:1000 concentration for molluscicidal activity against Biomphalaria pfeifferi in Machakos District, Kenya. Forty-seven of the 50 (94%) plants and 106 of the 134 (79%) plant materials (roots, stems, leaves, fruits, flowers and seeds) were molluscicidal. The leaves of Pappea capensis (Sapindaceae), Steganotaenia araliacea (Umbelliferae), Zornia setosa subsp. obvata (Papilionaceae) and Terminalia kilimandscharica (Combretaceae), the flower pods of Hyptis pectinata (Labiatae), the seeds of Acacia nilotica (Mimosaceae) and the fruits and roots of Solanum nigrum (Solanaceae) gave 100% kill. Another 15 species produced mortality rates between 53% and 87%. Plants were evaluated for possible use in local snail control programmes by considering their growing characteristics, habitat requirements, toxicity in non-target organisms, abundance in the study area and competing uses.