Water contact and Schistosoma haematobium infection: a case study from an upper Egyptian village.

The quantitative relationship between water contact and Schistosoma haematobium infection was studied in a cohort of male school children aged 6-17 in El Ayaisha village, Upper Egypt, during a two-year study. An exposure index (total body minutes, TBM) was used to identify the activities responsible for exposure to cercariae-infested water and to examine the relationship between water contact and infection. Results show that 65% of all contacts and 86% of all TBM were due to swimming in the Nile and canals and that swimming was the most important exposure and contamination activity. Using multivariate analysis, several sites, study periods, residence groups and mostly canal contacts were significantly correlated with egg-counts. Positive relationships could also be identified using egg-counts with water contact data from preceding study periods, indicating the influence of pre-existing infections, prepatency and seasonality of water contact and transmission. TBM were usually more significantly correlated with egg-counts than frequency and duration of contact. The relevance of the findings for control programmes and the use of school children and the exposure index for water contact studies are discussed.

Laboratory and field evaluation of a direct filtration technique for recovery of schistosome cercariae.

The use of cercariometry in epidemiological studies has been limited by turbidity, difficulty of recovering cercariae at low concentrations in natural waters, and by complex apparatus that requires a power source. The technique of differential filtration developed by Theron has been modified and tested in the laboratory and in the field in Upper Egypt for detection of Schistosoma haematobium cercariae. A recovery filter with a pore size of 30 micrometer was found to give the best results. The recovery rate in the laboratory was 51% on filtration of 5-liter samples of formalin-treated water, and 19-30% with 10- and 20-liter samples. This moderate efficiency is offset by simplicity of the technique, rapid filtration, and ease of reading the recovery filter, permitting sampling of large volumes of water in the field by persons with little training. Average densities of 0.024 cercariae per liter of water were found at the Nile and 0.029 cercariae per liter in the irrigation canals. Most cercariae were recovered between 0.700 and 0900 hours.

Additive host genetic factors influence fecal egg excretion rates during Schistosoma mansoni infection in a rural area in Brazil.

This study quantifies the influence of shared household and kinship on egg counts during Schistosoma mansoni infection in a sample from rural Brazil. Detailed genealogic information allowed assignment of 597 individuals to 6 multihousehold pedigrees residing in 145 households. A variance component method was used to partition egg counts into shared household, additive genetic, and individual-specific environmental effects. Host additive genetic effects consistently accounted for a large proportion of the variation in egg counts: 43% in an unadjusted model and 40% in model adjusted for covariates. In a model that examined the confounding of shared household with kinship, additive genetic effects still accounted for 27% of the variation in egg counts and shared household only 12%. The consistently important role for host additive genetic factors on the variation in egg counts points to new ways of modeling and understanding the mechanisms that contribute to trait variation during infection with S. mansoni.

Utilization of selected hospitals, health centres and health stations in central, southern and western Ethiopia.

This first, extensive, facility-based study of health services utilization in central, southern and western Ethiopia reveals steep distance decay gradients and underutilization of rural health services, the result of numerous geographical, socioeconomic, cultural and facility-based barriers. Out-patients statistics of 280,656 first-visit polyclinic patients in 8 hospitals, 8 health centres and 9 health stations in 7 administrative regions and of 10,885 sick children, 7767 antenatal attendants, 902 family planning acceptors, 275 vaccinated children and mothers and 1066 free patients, as well as in-patient statistics of 11,221 patients in 5 hospitals were analysed to determine catchment areas and utilization rates. On the average, 46% of the polyclinic patients were residents of the same town or village, 39% of the same awraja (district) and 5% of other administrative regions. Sick children, family planning attendants, free patients and in-patients lived relatively nearer to health facilities than polyclinic out-patients. Interviews with polyclinic out-patients showed that type and cost of transportation, type of illness, patient preferences, socioeconomic status of patients and referral patterns were important factors in utilization. Aggregation of all available health services data indicates that whereas some towns approach the targeted 2.5 per capita patient visits per year, coverage of the rural population is relatively low. Suggestions are made on how to overcome the problem of underutilization of rural health stations and to improve the health services information system.

Health aspects of resettlement in Ethiopia.

The literature on health implications and effects of government-sponsored resettlement in Ethiopia is reviewed with the objective of providing an initial evaluation of the health status of settlers and the health hazards of resettlement in western Ethiopia. Emphasis is on the 1984/85 resettlement program, which resulted in the movement of about 600,000 drought victims from northern and central Ethiopia to the western part of the country. Malaria, trypanosomiasis, onchocerciasis, yellow fever, nonfilarial elephantiasis, sand-flea infestation, and psychological stress are identified as immediate and greater health hazards than in the areas of settler origin, based on the geographic distribution and ecology of the major communicable, nutritional, and geochemical diseases in Ethiopia, and on the impact of program deficiencies on settler health. More studies are needed on the epidemiology and ecology of bancroftian filariasis, visceral leishmaniasis, dracunculiasis, eye and skin diseases, tuberculosis, meningitis, intestinal parasitism, diarrhea, and calorie/protein malnutrition before their public health and economic significance in settlements can be evaluated. Schistosomiasis appears to be less common, for the time being, in resettlement areas than in the areas of outmigration. Research needs and constraints in resettlement planning, implementation, and operation are identified, and some recommendations made for disease control programs.

Water resources development and schistosomiasis ecology in the Awash Valley, Ethiopia.

This paper examines the impact of water resources development, particularly river regulation and irrigated agriculture, on the occurrence of schistosomiasis and its intermediate host snails in the Awash Valley. An ecologic-geographic approach based on: a combination of comparative schistosomiasis prevalence and human ecological studies of indigenous seminomadic pastoralists and migrant laborers from the Ethiopian highlands; analysis of snail intermediate host ecology-geography; and longitudinal studies of water resources development, is used to evaluate the endemicity status and changing spatial distribution of schistosomiasis mansoni and schistosomiasis haematobium. This study confirms the suitability of epidemiologic-ecologic methods for analyzing relationships between causal processes and the spatiality of schistosomiasis. In this context local schistosomiasis control programs are reviewed and recommendations made for their improvements.

Primary health care in Ethiopia under three political systems: community participation in a war-torn society.

This paper examines primary health care (PHC) development with an emphasis on community participation in Ethiopia under the feudal regime of emperor Haile Sellassie, the socialist/military rule of Mengistu Haile Mariam and the sprouting democracy and free market economy of Meles Zenawi. In spite of the rapid expansion of primary care under Mengistu, community participation was hampered by the protracted war and centralized, urban-based, bureaucratic approaches and attitudes that failed to promote an enabling environment for community participation. The socialist government, although implementing various community programs and expanding the rural health services, did not succeed in revolutionizing the health services. A comparative examination of the democratized rebel health services of the Eritrean People's Liberation Front (EPLF) and the Tigray People's Liberation Front (TPLF) illustrates the inconsistencies between stated policies of the Ethiopian government and actual strategies, and identifies factors promoting and impeding participatory health care development in a war environment. Achievements, opportunities and potential dangers to PHC and community participation in the post-war era characterized by economic progress, democratization, decentralization, lingering ethnic conflict and private initiatives are briefly described.

Human behavior, health education and schistosomiasis control: a review.

This paper examines the role of human behavior in schistosomiasis transmission and control in relation to health education. The literature is reviewed to identify relevant behaviors and to examine progress and constraints in health education, using the primary health care approach. The behavior model by Dunn and the PRECEDE health education model by Green and coworkers are adapted for health education in schistosomiasis control. Because of its focus on the role of individual and community vs outside factors, deliberate vs non-deliberate behavior and health-enhancing and health-maintaining vs health-lowering behavior, Dunn's model can evaluate social, economic, cultural and political factors in schistosomiasis transmission and control that must be considered in health education. The PRECEDE model represents a suitable diagnostic tool for health education planning, intervention and evaluation.

Utilization of pharmacies and pharmaceutical drugs in Addis Ababa, Ethiopia.

This paper examines recent developments in the pharmaceutical retail trade in socialist Ethiopia and presents the results of two surveys on pharmacy utilization in Addis Ababa. Surveys were carried out in 6 private and 5 government pharmacies. Objectives are: (1) to examine drug retailer utilization in relation to locational, transportation and retailer-related factors; (2) evaluate the role of socioeconomic factors in pharmacy and drug utilization; and (3) determine distance decay associated with clients' trip origins and the location of their residences as indicators of service areas. Although most clients originated in Addis Ababa, large numbers came from rural areas, especially in the pharmacies near large markets and other shopping areas in the inner city. Centrally located retailers also served more Addis Ababa residents and larger sections of the city than peripherally located retailers, largely due to a combination of urban structure, distribution of health care facilities, prevailing drug shopping behavior and population distribution. Government pharmacies had larger service areas and served larger numbers of clients than private pharmacies, primarily due to lower prices and greater availability of pharmaceuticals. Mean distance from pharmacies to places of origin of trips was smaller than mean distance from pharmacies to residences of the same clients. Similarly, distance decay gradients were steeper for the former than the latter in the 4 pharmacies studied in the second part of the survey, indicating the greater suitability of origin of trip as a parameter of service area. Type and price of drugs purchased were associated with socioeconomic factors, particularly level of education and housing/environmental health conditions in two districts, but there was little variation in the small number of drugs purchased per client. Several forms of drug-purchasing behavior of pharmacy clients and selling practices of private retailers are described as adaptive responses to prevailing economic and sociopolitical conditions. The study concludes that population-based studies of disease occurrence and health behavior are needed to better evaluate the health needs of the population for the planning of additional drug retailers in Addis Ababa's suburban districts.

Coping with intestinal illness among the Kamba in Machakos, Kenya, and aspects of schistosomiasis control.

In a hyperendemic schistosomiasis mansoni area in Machakos District, Kenya, the Kamba use modern and traditional health services interchangeably with similar results. Schistosomiasis oral drug therapy administered through the Schistosomiasis Research Project reportedly achieved significantly higher cure rates than hospital and health center treatment, which in turn was not more effective than traditional medicine. Kamba knowledge and perceptions of the causes of intestinal illness, several types of preventive behavior, the role of women as health promotors, development of community water supplies and the utilization of plant molluscicides are briefly evaluated for possible use in the planned national schistosomiasis control program.

Schistosomiasis in Ethiopia.

The literature on schistosomiasis in Ethiopia is reviewed with the objective of bringing together in one paper diverse sources which may not be available to those interested in schistosomiasis. Particular attention is given to the influence of altitude and climate, snail ecology and government economic programs on the distribution of schistosomiasis. Out of 365 communities studied between 1961 and 1986 for Schistosomiasis mansoni, cases were reported from 225 (62%), and in 85 (23%) the prevalence ranged from 10 to 92%. Most transmission sites and S. mansoni infections are in agricultural communities along streams between 1300 and 2000 m altitude infested with Biomphalaria pfeifferi, the major snail intermediate host. S. mansoni transmission above 2200 m and below 800 m is precluded in many parts of Ethiopia by low and high water temperatures, respectively. Schistosomiasis haematobium cases have been reported from 30 of the 54 communities studied, 17 of them with infection rates between 14 and 75%. Endemic S. haematobium appears to be confined in its distribution to lowlands below 800 m altitude. The highly focal distribution of S. haematobium transmission is largely due to the nonsusceptibility of most bulinine snails to the Ethiopian strain of the parasite and low water temperatures in the highlands. Water resources development, resettlement programs, refugee migration and other population movements may result in the spread of endemic S. mansoni. Lack of information on snail host/parasite relationships and the ecology of proven and suspected snail hosts does not permit predictions on the spread of endemic S. haematobium. Past and present schistosomiasis control programs in Ethiopia are reviewed and recommendations made for the national control program.

Illness and health behaviour in Addis Ababa and rural central Ethiopia.

This paper examines the results of health surveys among 544 randomly selected households (2829 people) in seven kebele (urban dwellers' associations) in Addis Ababa and Kaliti, an industrial suburb of Addis Ababa, and in four rural villages in two peasant associations. The major objective was to study illness distribution and health behaviour among different socioeconomic and cultural groups in urban and rural communities within the context of available health resources, national health policy and planning. Results show that in spite of the rapid expansion of health services since the Ethiopian revolution serious problems of allocation and access persist. Higher illness prevalance rates were found in rural areas (23.2%), Kaliti (25.5%) and in the low socioeconomic kebele in Addis Ababa (23.9%) than in the high socioeconomic kebele (16.5%), but rural/urban and intraurban differences were greater than reported here due to underreporting. One-third of all illnesses were treated by modern services, 19.9% by self care and 26.0% by traditional medicine and transitional healers, with 21.5% of all illnesses not being treated. Utilization rates varied with type and duration of illness, socioeconomic level, age, sex and place of residence. The role of distance and other contact barriers, treatment outcome and availability of private clinics and alternative health resources in utilization is also evaluated. Coverage of the modern health services was associated with socioeconomic status and mobility of patients as well as availability of health services.

Water contact behavior and schistosomiasis in an upper Egyptian village.

Preliminary findings of a study of the role of microspatial behavior and local ecological circumstances in the persistence of Schistosoma haematobium infection in El Ayaisha village, Upper Egypt, are presented. Twelve types of water contact activities were studied in three cohorts of 274,324 and 392 male students aged 5-16 during a 2-year period. Swimming and playing resulted in more frequent and intensive contact with potentially infective water and in more pollution of snail habitats with schistosome eggs than any other type of activity. Irrigation was probably not a major cause of S. haematobium infection in schoolboys and drinking water and fishing carried the smallest risk for this age group. Mapping and discriminate analysis of infection and transmission indicators revealed spatial associations between water contact, schistosome transmission and infection among the various age groups. The highest egg excretion rates in individuals and the highest prevalence rates were noted in the neighborhoods nearest to the canals. Water contact and contamination of water by the heavily infected school age boys is seasonally concentrated during the summer, when intermediate host snails and infective cercariae are also most common in the water. Frequency, type and duration of water contact change with age together with types of water bodies used, causing corresponding changes in exposure risk. Nevertheless, other factors, including acquired immunity, preexisting infections, chemotherapy and the effect of the study on the normal water contact behavior of the study population must also be evaluated. Contact with the Nile and the canals by the general nonschool population of El Ayaisha was studied to verify the observations among the schoolboys and to study socially linked activities and the transmission potential of the various transmission sites. Results are evaluated in regard to the feasibility of various schistosomiasis control measures in El Ayaisha.

STDS in women attending family planning clinics: a case study in Addis Ababa.

For cultural reasons modern contraception has been slow to gain acceptance in Ethiopia. Knowledge about contraception and abortion is still limited in many family and community settings in which it is socially disapproved. By 1990 only 4% of Ethiopian females aged 15-49 used contraception. Little is known of sexually transmitted disease (STD) prevalence in family planning (FP) attenders in Africa in general and Ethiopia in particular, even though attenders of family planning clinics (FPCs) are appropriate target groups for epidemiological studies and control programmes. A study of 2111 women of whom 542 (25.7%) attended FPCs in Addis Ababa showed utilisation rates to be highest in women who were: Tigre (33%) or Amhara (31%), aged 20-34 years (30%), age 16 or older at first marriage/coitus (28%:38% in those first married after 25 years); who had a monthly family income of 10 Ethiopian Birr (EB) or more (33%:36% for those with income 100-500 EB), three or more children (37%), more than five lifetime husbands/sexual partners (39%); or were bargirls (73%) or prostitutes (43%). The seroprevalence rates for all STDs, higher in FPC attenders compared with other women, were syphilis (TPHA) 39%, Neisseria gonorrhoeae 66%, genital chlamydia 64%, HSV-2 41%, HBV 40% and Haemophilus ducreyi 20%. Only 4% of FPC attenders had no serological evidence of STD: 64% were seropositive for 3 or more different STD. Clinical evidence of pelvic inflammatory disease (PID) was also more common in the FPC attenders (54%), 37% having evidence of salpingitis. The FPC provides a favourable setting for screening women likely to have high seroprevalence of STD, who for lack of symptoms will not attend either an STD clinic nor a hospital for routine check up. We recommend that measures be taken to adequately screen, treat and educate FPC attenders, their partners, and as appropriate and when possible their clients, in an attempt to control STDs and ultimately HIV in the community. Social, economic and cultural factors in the occurrence of STDs, prostitution, family planning and modern contraception coverage in Ethiopia are identified and deficiencies of current programmes briefly discussed with the objective of targeting services more effectively.

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.

Transmission patterns of onchocerciasis in southwest Ethiopia.

The three transmission patterns found till now in Ethiopia are described. The forest area contains ideal conditions for the breeding of Simulium, but the sparse human population makes the transmission rate low. Only a few people were found to be infected. The subsistence crop farming area is a less ideal habitat for the vector due to the scarcity of bush and shade. However the presence of a largest population can explain the slightly higher prevalence of the disease than in the forest. The coffee farming area is densely populated, rich in bush and shade, with heavy rainfall and numerous rivers. Here the number of Simulium and their chance to reach the infective stages, are considered to be high. A high prevalence of the disease was found in this zone.

Onchocerciasis, malaria and trypanosomiasis in three resettlement schemes in western Ethiopia.

Epidemiological studies were carried out among 180 randomly chosen settler and 180 non-settler households in the three resettlement schemes of Kishe, Gera and Didessa located in river valleys and highland areas of Illubabor Administrative Region in western Ethiopia. Up to 49% of the indigenous populations (in Kishe) and 0.9% of the settlers had onchocerciasis, with a mean density of 13.6 filariae per slide/skin snip for indigenous people and 9.4 for settlers. Onchocerciasis prevalence rates were higher in males than females and were highest in the 20-59 age group. In the Kishe scheme, rates were inversely related to distance between residences and probable forest/stream habitat of Simulium damnosum. No onchocerciasis transmission appears to occur in the Gera scheme at 1,950 meters altitude, apparently due to the absence of suitable vectors. Eight of 622 (1.2%) persons had malaria (P. vivax and P. falciparum). The most common man-biting anophelines were A. gambiae and A. funestus. No human trypanosomiasis cases were found but high livestock mortality was reported by local populations in the lowland schemes of Kishe and Didessa.

Trichloroethylene, tetrachloroethylene, nitrates, and other chemicals in well water in the Fresno-Clovis Metropolitan Area.

In this study, the author examined the spatial and temporal distribution of tetrachloroethylene, trichloroethylene, nitrate, and several other organic and inorganic chemicals in large community wells in the Fresno-Clovis Metropolitan Area and estimated the lifetime cancer risk associated with exposure to tetrachloroethylene and trichloroethylene. By 1992-1993, investigators found the industrial solvent tetrachloroethylene in 34 wells and found trichloroethylene in 16 wells. All wells had detectable levels of nitrate. In addition, investigators found radon, arsenic, cadmium, iron, manganese, trihalomethanes, and several other volatile organic chemicals in the wells, but only radon and arsenic posed a significant health risk. In 1995, 16 wells were closed because chemicals were found in them. Twenty-six of 248 (10.5%) active wells and 24 of 43 (55.8%) closed wells contained multiple contaminants, excluding nitrate. Between 1988 and 1993, concentrations of trichloroethylene, tetrachloroethylene, and nitrates increased in selected wells. Daily, monthly, and bimonthly variations in the concentrations of tetrachloroethylene, trichloroethylene, and nitrate were often considerable. Granulated activated carbon filtration reduced trichloroethylene levels in well water by 91%-95%, and the author examined its usefulness as a remedial measure. Estimated lifetime cancer risks for tetrachloroethylene and trichloroethylene were 1 excess cancer death per 9.5 million people and 1 excess death per 250 million, respectively. The author also included recommendations for the conduct of further epidemiological and environmental studies.

1,2 Dibromo-3-chloropropane (DBCP) and ethylene dibromide (EDB) in well water in the Fresno/Clovis metropolitan area, California.

Ground-water contamination with the pesticides 1,2 dibromo-3-chloropropane (DBCP) and ethylene dibromide (EDB) affects Fresno/Clovis city in California. The spatial and temporal distribution of DBCP and EDB in public wells in Fresno/Clovis was examined, using mapping and time-series analyses of chemical test results, during the time periods 1979-1980 and 1992-1993. Health risks were estimated from mean concentrations, lifetime cancer risks were estimated, and monitoring and control programs were reviewed. Mean DBCP concentrations in selected wells declined from 0.56 ppb in 1979-1980 to 0.18 ppb in 1992-1993. Closure of wells and wellhead filtration caused levels to be reduced further (i.e., to 0.06 ppb). Mean EDB concentrations declined from 0.25 ppb to 0.15 ppb during the same time periods. The estimated lifetime cancer risk for DBCP was 1 excess death per 125 000 population in 1992-1993, but this risk varied within the city. The risk for EDB was 1 excess death per 2.2 million. Recommendations were made for the modeling of pesticide movement in ground water and for epidemiological studies.

Sociocultural aspects of schistosomiasis mansoni in an endemic area in Minas Gerais, Brazil.

A study to determine the sociocultural factors influencing knowledge, attitudes, and practices of individuals from a small community toward Schistosoma mansoni infection was carried out in an endemic area in the State of Minas Gerais, Brazil. The study used qualitative approaches to collect data from school-aged children and teachers. Specific findings were that the individuals interviewed were aware of the disease, but also held inaccurate popular beliefs about transmission. Misconceptions coexisted with accurate knowledge both in children and teachers. The disease was not seen as a major health problem and does not affect their activities since it does not cause severe symptoms in most of the individuals. Although the majority of the participants relate transmission to water and lack of sanitation, they do not take any preventive measures since their subsistence is highly dependent on irrigation, farming, fishing, and other essential work that is directly related to water activities. The authors discuss the development of a health education program based on the knowledge and perception of individuals about the disease and its determinants as being important for the context and behavioral change.