Showing papers in "Tropical Medicine & International Health in 2004"

Household drinking water in developing countries: a systematic review of microbiological contamination between source and point‐of‐use

Abstract: Summary objective To assess the extent and causes of microbiological contamination of household drinking water between source and point-of-use in developing countries. methods A systematic meta-analysis of 57 studies measuring bacteria counts for source water and stored water in the home to assess how contamination varied between settings. results The bacteriological quality of drinking water significantly declines after collection in many settings. The extent of contamination after water collection varies considerably between settings, but is proportionately greater where faecal and total coliform counts in source water are low. conclusions Policies that aim to improve water quality through source improvements may be compromised by post-collection contamination. Safer household water storage and treatment is recommended to prevent this, together with point-of-use water quality monitoring.

Historical review of malarial control in southern African with emphasis on the use of indoor residual house-spraying

Abstract: Indoor residual house-spraying (IRS) mainly with dichlorodiphenyltrichloroethane (DDT) was the principal method by which malaria was eradicated or greatly reduced in many countries in the world between the 1940s and 1960s. In sub-Saharan Africa early malarial eradication pilot projects also showed that malaria is highly responsive to vector control by IRS but transmission could not be interrupted in the endemic tropical and lowland areas. As a result IRS was not taken to scale in most endemic areas of the continent with the exception of southern Africa and some island countries such as Reunion, Mayotte, Zanzibar, Cape Verde and Sao Tome. In southern Africa large-scale malarial control operations based on IRS with DDT and benzene hexachloride (BHC) were initiated in a number of countries to varying degrees. The objective of this review was to investigate the malarial situation before and after the introduction of indoor residual insecticide spraying in South Africa, Swaziland, Botswana, Namibia, Zimbabwe and Mozambique using historical malarial data and related information collected from National Malaria Control Programmes, national archives and libraries, as well as academic institutions in the respective countries. Immediately after the inception of IRS with insecticides, dramatic reductions in malaria and its vectors were recorded. Countries that developed National Malaria Control Programmes during this phase and had built up human and organizational resources made significant advances towards malarial control. Malaria was reduced from hyper- to meso-endemicity and from meso- to hypo-endemicity and in certain instances to complete eradication. Data are presented on the effectiveness of IRS as a malarial control tool in six southern African countries. Recent trends in and challenges to malarial control in the region are also discussed.

Out-of-pocket health expenditure and debt in poor households: evidence from Cambodia.

Abstract: Summary objectives To document how out-of-pocket health expenditure can lead to debt in a poor rural area in Cambodia. methods After a dengue epidemic, 72 households with a dengue patient were interviewed to document health-seeking behaviour, out-of-pocket expenditure, and how they financed such expenditure. One year later, a follow-up visit investigated how the 26 households with an initial debt had coped with it. results The amount of out-of-pocket health expenditure depended mostly on where households sought care. Those who had used exclusively private providers paid on average US$103; those who combined private and public providers paid US$32, and those who used only the public hospital US$8. The households used a combination of savings, selling consumables, selling assets and borrowing money to finance this expenditure. One year later, most families with initial debts had been unable to settle these debts, and continued to pay high interest rates (range between 2.5 and 15% per month). Several households had to sell their land. conclusions In Cambodia, even relatively modest out-of-pocket health expenditure frequently causes indebtedness and can lead to poverty. A credible and accessible public health system is needed to prevent catastrophic health expenditure, and to allow for other strategies, such as safety nets for the poor, to be fully effective.

Risk factors and clinical features associated with severe dengue infection in adults and children during the 2001 epidemic in Chonburi, Thailand

Abstract: Summary objectives Dengue haemorrhagic fever (DHF) is an important cause of morbidity in South-east Asia and used to occur almost exclusively in young children. In recent years, there has been a progressive shift in age-distribution towards older children and adults. We investigated an outbreak in 2001 in both children and adults, in an endemic area of Thailand. methods Retrospective study of 347 patients with serologically confirmed dengue infection admitted to Chonburi Hospital during an epidemic in 2001. results A total of 128 (37%) patients had dengue fever (DF) and 219 (63%) had DHF. Patients with DHF were significantly older than patients with DF (11 years vs. 8 years). Clinical bleeding was noted in 124 individuals, both with DF (n ¼ 24) and DHF (n ¼ 100), and significantly more frequently in adults. Twenty-nine (13.2%) of all DHF cases were caused by primary infection. Secondary dengue infection was associated significantly with the development of DHF in children, OR (95% CI) ¼ 3.63 (1.94‐ 6.82), P < 0.0001, but not in adults, OR (95% CI) ¼ 0.6 (0.02‐6.04), P ¼ 1. Unusual clinical manifestations were observed in 23 patients: three presented with encephalopathy and 20 with highly elevated liver-enzymes. In the latter group, four patients were icteric and nine had gastrointestinal bleeding. conclusion These results indicate that DHF in South-east Asia is common in both children and adults. In dengue-endemic countries, dengue should be considered as a differential diagnosis in patients with clinical gastrointestinal bleeding in association with increased liver enzymes.

Spatial clustering of malaria and associated risk factors during an epidemic in a highland area of western Kenya

Abstract: The epidemiology of malaria over small areas remains poorly understood, and this is particularly true for malaria during epidemics in highland areas of Africa, where transmission intensity is low and characterized by acute within and between year variations We report an analysis of the spatial distribution of clinical malaria during an epidemic and investigate putative risk factors Active case surveillance was undertaken in three schools in Nandi District, Western Kenya for 10 weeks during a malaria outbreak in May-July 2002 Household surveys of cases and age-matched controls were conducted to collect information on household construction, exposure factors and socio-economic status Household geographical location and altitude were determined using a hand-held geographical positioning system and landcover types were determined using high spatial resolution satellite sensor data Among 129 cases identified during the surveillance, which were matched to 155 controls, we identified significant spatial clusters of malaria cases as determined using the spatial scan statistic Conditional multiple logistic regression analysis showed that the risk of malaria was higher in children who were underweight, who lived at lower altitudes, and who lived in households where drugs were not kept at home

Fake antimalarials in Southeast Asia are a major impediment to malaria control: multinational cross‐sectional survey on the prevalence of fake antimalarials

Abstract: OBJECTIVE To assess the prevalence of counterfeit antimalarial drugs in Southeast (SE) Asia. DESIGN Cross-sectional survey. SETTING Pharmacies and shops selling antimalarial drugs in Myanmar (Burma), Lao PDR, Vietnam, Cambodia and Thailand. MAIN OUTCOME MEASURES Proportion of artemisinin derivatives or mefloquine containing drugs of substandard quality. RESULTS Of the 188 tablet packs purchased which were labelled as 'artesunate' 53% did not contain any artesunate. All counterfeit artesunate tablets were labelled as manufactured by 'Guilin Pharma', and refinements of the fake blisterpacks made them often hard to distinguish from their genuine counterparts. No other artemisinin derivatives were found to be counterfeited. Of the 44 mefloquine samples, 9% contained <10% of the expected amount of active ingredient. CONCLUSIONS An alarmingly high proportion of antimalarial drugs bought in pharmacies and shops in mainland SE Asia are counterfeit, and the problem has increased significantly compared with our previous survey in 1999-2000. This is a serious threat to public health in the region.

A randomized trial on acceptability of voluntary HIV counselling and testing.

Abstract: OBJECTIVES To examine factors affecting readiness for and acceptability of voluntary HIV counselling and testing (VCT). METHODS Participants in a population-based HIV survey conducted in an urban population in Zambia in 1996 were offered VCT. Although 29% of them expressed interest in being tested (readiness), only 4% of this group used the services (i.e. acceptability). When the survey was repeated 3 years later, VCT was designed differently to assess acceptability. At the cluster level the participants were randomly allocated to VCT either at the local clinic (similar to 1996, n = 1102) or at an optional location (n = 1343). RESULTS Readiness varied significantly by age group (47% in age group 20-24 years vs. 18% in age group 40-49 years). There were contrasts between young (15-24 years) and older age groups (25-49 years) regarding the main factors associated with readiness. Whereas self-perceived risk of being HIV infected was the only significant factor among the young, poor self-rated health and ever HIV tested were important factors among the older. The acceptability was 11.8% among the group allocated to VCT at the local clinic compared with 55.8% for the group allocated to an optional location (RR, 4.7). CONCLUSIONS Perceived risk of HIV infection had a major influence on VCT readiness among young people, whereas declining general health status, as indicated by self-rated health, was most evident among those of older age. A strong effect of placement on acceptability of VCT was demonstrated, indicating this barrier to be important in explaining low demands for VCT in the past. Differences in perceptions of how confidentiality is handled at the two locations might be an important underlying factor.

Prevalence of Opisthorchis viverrini infection and incidence of cholangiocarcinoma in Khon Kaen, Northeast Thailand

Abstract: Liver cancer is the most common cancer in Khon Kaen, Northeast Thailand, because of the high incidence of cholangiocarcinoma (CHCA). Opisthorchis viverrini (OV), a liver fluke, is endemic in the area, and has been evaluated as a cause of CHCA by International Agency for Research on Cancer. Residents of 20 districts in the province were invited to attend a mobile screening programme between 1990 and 2001. Of 24 723 participants, 18 393 aged 35-69 years were tested for OV infection, by examining stools for the presence of eggs. Prevalence of infection in each district was estimated from the sample of the population who had been tested. The incidence of liver cancer in 1990-2001 was obtained for each district from the cancer registry. The average crude prevalence of OV infection in the sample subjects was 24.5%, ranging from 2.1% to 70.8% in different districts. Truncated age-standardized incidence of CHCA at ages >35 years varied threefold between districts, from 93.8 to 317.6 per 100,000 person-years. After adjustment for age group, sex and period of sampling, there was a positive association between prevalence of OV infection and incidence of CHCA at the population level. Associations between CHCA and active OV infection in individuals have become hard to demonstrate, because of effective anti-OV treatment. The relationship may, however, be clear in comparisons between populations, which, for infectious diseases, take into account the contextual effects of group exposure in determining individual outcome. The cancer registry is an appropriate tool for disease monitoring in small areas.

The practical importance of permanent and semipermanent habitats for controlling aquatic stages of Anopheles gambiae sensu lato mosquitoes: operational observations from a rural town in western Kenya.

Abstract: Control of aquatic-stage Anopheles is one of the oldest and most historically successful interventions to prevent malaria, but it has seen little application in Africa. Consequently, the ecology of immature afrotropical Anopheles has received insufficient attention. We therefore examined the population dynamics of African anopheline and culicine mosquitoes using operationally practicable techniques to examine the relative importance and availability of different larval habitats in an area of perennial malaria transmission in preparation for a pilot-scale larval control programme. The study was conducted in Mbita, a rural town on the shores of Lake Victoria in Western Kenya, over 20 months. Weekly larval surveys were conducted to identify the availability of stagnant water, habitat characteristics and larval densities. Adult mosquitoes were collected indoors at fortnightly intervals. Availability of aquatic habitats and abundance of mosquito larvae were directly correlated with rainfall. Adult mosquito densities followed similar patterns but with a time-lag of approximately 1 month. About 70% of all available habitats were man-made, half of them representing cement-lined pits. On average, 67% of all aquatic habitats on a given sampling date were colonized by Anopheles larvae, of which all identified morphologically were A. gambiae sensu lato. Natural and artificial habitats were equally productive over the study period and larval densities were positively correlated with presence of tufts of low vegetation and negatively with non-matted algal content. The permanence of a habitat had no significant influence on larval productivity. We conclude that A. gambiae is broadly distributed across a variety of habitat types, regardless of permanence. All potential breeding sites need to be considered as sources of malaria risk at any time of the year and exhaustively targeted in any larval control intervention.

The impact of HIV/AIDS on labour productivity in Kenya.

Abstract: OBJECTIVES To estimate the impact of HIV/AIDS on individual labour productivity during disease progression. METHODS We used a retrospective cohort design to study the productivity and attendance of tea estate workers who died or were medically retired because of AIDS-related causes between 1997 and 2002 in western Kenya. We compared daily output in kilograms of tea leaves plucked, use of paid and unpaid leave and assignment to less strenuous tasks by 54 workers who died or were medically retired because of AIDS to those of comparison workers, matched on time and tea field using longitudinal regression. RESULTS HIV-positive workers plucked less tea in the 18 months preceding AIDS-related termination and used more leave in the 3 years before termination. After adjusting for age and environmental factors, cases plucked between 4.11 and 7.93 kg/day less in the last year and a half before termination. Cases used between 9.2 and 11.0 more sick leave days, between 6.4 and 8.3 more annual leave days, between 19.9 and 11.8 more casual leave days, and spent between 19.2 and 21.8 more days doing less strenuous tasks in the 2 years before termination than did comparison pluckers. Tea pluckers who terminated because of AIDS-related causes earned 16.0% less in their second year before termination and 17.7% less in the year before termination. CONCLUSION These results provide empirical estimates of the impact of HIV/AIDS on labour productivity. As workers often bring unrecorded 'helpers', actual differences may be greater. Decreased attendance and output may put sick workers in jeopardy of losing their jobs and impose financial burdens on employers.

Epidemiology and geography of Schistosoma mansoni in Uganda: implications for planning control

Abstract: Intestinal schistosomiasis caused by infection with Schistosoma mansoni is a widespread public health problem in Uganda. Although long known to be endemic, its current distribution within the country requires updating of parasitological data to help guide planned control. We report such data collected between 1998 and 2002 from 201 schools and 68 communities across Uganda. In accordance with epidemiological expectation, prevalence and intensity increased with age, peaking at 10-20 years and thereafter declined moderately with age, whereas intensity declined more rapidly with age, and the prevalence of infection in a school was non-linearly related to the mean intensity of infection. We used geographical information systems to map the distribution of infection and to overlay parasitological data with interpolated environmental surfaces. The derived maps indicate both a widespread occurrence of infection and a marked variability in infection prevalence, with prevalence typically highest near the lakeshore and along large rivers. No transmission occurred at altitudes >1400 m or where total annual rainfall was <900 mm; limits which can help estimate the population at risk of schistosomiasis. The results are discussed in reference to the ecology of infection and provide an epidemiological framework for the design and implementation of control efforts underway in Uganda.

Waiting too long: low use of maternal health services in Kalabo, Zambia.

Abstract: OBJECTIVE To determine the level of use of maternal health services and to identify and assess factors that influence women's choices where to deliver in Kalabo District, Zambia. METHODS A cross-sectional descriptive study conducted between 1998 and 2000, with 332 women interviewed using semi-structured questionnaires. Focus group discussions were held and hospital data and registers were checked. RESULTS Although 96% of respondents would prefer to deliver in a clinic, only 54% actually did, because of long distances, lack of transport, user fees, lack of adequate health education given during antenatal clinic attendances, poorly staffed and ill-equipped institutions with poorly skilled personnel. CONCLUSION Unmarried women, women with higher education and women with formal employment, who are able to pay the user fees and live near a clinic are more likely to deliver in a clinic. This does not guarantee survival, however; maternal mortality is high in the district; health facilities are poorly staffed, poorly skilled and ill-equipped.

Exploring 30 years of malaria case data in KwaZulu-Natal South Africa Part II. The impact of non-climatic factors.

Abstract: Large parts of Africa are prone to malaria epidemics. Advance epidemic warning would give health services an opportunity to prepare. Because malaria transmission is largely limited by climate, climate-based epidemic warning systems are a real possibility. To develop and test such a system, good long-term malaria and climate data are needed. In KwaZulu-Natal (KZN), South Africa, 30 years of confirmed malaria case data provide a unique opportunity to examine short- and long-term trends. We analysed seasonal case totals and seasonal changes in cases (both log-transformed) against a range of climatic indicators obtained from three weather stations in the highest malaria incidence districts, using linear regression analysis. Seasonal changes in case numbers (delta log cases, dlc) were significantly associated with several climate variables. The two most significant ones were mean maximum daily temperatures from January to October of the preceding season (n=30, r2=0.364, P=0.0004) and total rainfall during the current summer months of November-March (n=30, r2=0.282, P=0.003). These two variables, when entered into the same regression model, together explained 49.7% of the total variation in dlc. We found no evidence of association between case totals and climate. In KZN, where malaria control operations are intense, climate appears to drive the interannual variation of malaria incidence, but not its overall level. The accompanying paper provides evidence that overall levels are associated with non-climatic factors such as drug resistance and possibly HIV prevalence.

Maternal anaemia and its impact on perinatal outcome.

Abstract: OBJECTIVE To find out the relationship between maternal anaemia and perinatal morbidity and mortality. METHOD A cohort of 629 pregnant women was studied from October 2001 to October 2002. Of these, 313 were anaemic (haemoglobin 11 g/dl at all times in pregnancy and were labelled as non-anaemic. Perinatal outcomes included preterm delivery, low birth weight (LBW) at delivery, intrauterine growth restriction, perinatal mortality, APGAR score at 1 and 5 min, intrauterine foetal demise (IUD). RESULTS The risk of preterm delivery and LBW among exposed group was 4 and 1.9 times higher among anaemic women, respectively. Newborns of anaemic mothers had 1.8 times increased risk of having an APGAR score of <5 at 1 min and the risk of IUD was 3.7 times higher for anaemic women. CONCLUSION Low maternal haemoglobin levels are associated with increased risk of preterm delivery, LBW babies, APGAR score <5 at 1 min and IUD.

Impact of malaria control on childhood anaemia in Africa – a quantitative review

Abstract: OBJECTIVE To review the impact of malaria control on haemoglobin (Hb) distributions and anaemia prevalences in children under 5 in malaria-endemic Africa. METHODS Literature review of community-based studies of insecticide-treated bednets, antimalarial chemoprophylaxis and insecticide residual spraying that reported the impact on childhood anaemia. Anaemia outcomes were standardized by conversion of packed cell volumes into Hb values assuming a fixed threefold difference, and by estimation of anaemia prevalences from mean Hb values by applying normal distributions. Determinants of impact were assessed in multivariate analysis. RESULTS Across 29 studies, malaria control increased Hb among children by, on average, 0.76 g/dl [95% confidence interval (CI): 0.61-0.91], from a mean baseline level of 10.5 g/dl, after a mean of 1-2 years of intervention. This response corresponded to a relative risk for Hb < 11 g/dl of 0.73 (95% CI: 0.64-0.81) and for Hb < 8 g/dl of 0.40 (95% CI: 0.25-0.55). The anaemia response was positively correlated with the impact on parasitaemia (P = 0.005, P = 0.008 and P = 0.01 for the three outcome measures), but no relationship with the type or duration of malaria intervention was apparent. Impact on the prevalence of Hb < 11 g/dl was larger in sites with a higher baseline parasite prevalence. Although no age pattern in impact was apparent across the studies, some individual trials found larger impacts on anaemia in children aged 6-35 months than in older children. CONCLUSION In malaria-endemic Africa, malaria control reduces childhood anaemia. Childhood anaemia may be a useful indicator of the burden of malaria and of the progress in malaria control.

Melioidosis epidemiology and risk factors from a prospective whole-population study in northern Australia

Abstract: Summary Objectives The aims of this study were to describe the epidemiology of melioidosis in tropical northern Australia and to assess the importance of defined risk factors. Methods The data were taken from a 14-year prospective study of 364 cases of melioidosis in the ‘Top End’ of the Northern Territory. A whole-population logistic regression model was used to estimate the crude and adjusted relative risk (RR) for the defined risk factors. Results The mean age of the study population was 46.8 years, 264 (72.5%) were male, 178 (49%) were aboriginal Australians and 59 (16.2%) died from melioidosis. Average annual incidence was 19.6 cases per 100 000 population, with an estimated rate of 260 cases per 100 000 diabetics per year. Using a whole-population logistic regression model, the estimated crude and adjusted RR [95% confidence intervals (CI)] for melioidosis were 6.3 (5.1–7.8) and 4.0 (3.2–5.1) for those aged ≥ 45 years, 2.3 (1.8–2.9) and 2.4 (1.9–3.0) for males, 2.9 (2.3–3.5) and 3.0 (2.3–4.0) for aboriginal Australians, 21.2 (17.1–26.3) and 13.1 (9.4–18.1) for diabetics, 2.7 (2.2–3.4) and 2.1 (1.6–2.6) for those with excess alcohol consumption, 6.8 (5.4–8.6) and 4.3 (3.4–5.5) for chronic lung disease and 6.7 (4.7–9.6) and 3.2 (2.2–4.8) for chronic renal disease, respectively. Conclusions Diabetes, excess alcohol intake, chronic renal disease and chronic lung disease are each independent risk factors for melioidosis. In tropical northern Australia, male sex, aboriginal ethnicity and age of ≥45 years are also independent predictors for melioidosis. Impaired polymorph function may be critical in the predisposition to melioidosis.

Malaria transmission and major malaria vectors in different geographical areas of Southeast Asia.

Abstract: Summary During the last decade, major progress in malaria control has been achieved in Vietnam, Laos and Cambodia. However, malaria is still a potentially fatal disease in some hilly-forested areas and continues to be endemic in a few coastal foci. To estimate the risk that stems from the major vectors after a decade of intensive malaria control, an entomological study based on human landing collections was conducted between April 1998 and November 2000 in six study villages (four in Vietnam, one in Cambodia and one in Laos) located in different physio-geographical areas. Five villages were selected in places where new cases of malaria still occurred. In the sixth village, in the northern hilly area of Vietnam, no case of malaria was detected during the past 3 years. In three study villages of the hilly forested areas of Cambodia and central Vietnam, Anopheles dirus A still played an important role in malaria transmission and maintain perennial transmission inside the villages despite its low density. Anopheles minimus A was found in all study villages except in the southern coastal village of Vietnam. Its role in malaria transmission, however, varied between localities and surveys. In one study village of central Vietnam it was almost absent (one specimen collected over 480 man nights), and in another village sporozoite positive specimens (2.8%) were only observed during the first two surveys whereas this species disappeared from the collections from November 1998 onwards (six surveys: 360 man nights). In the northern study site An. minimus A and C were found in all collections, but no local malaria transmission occurred. However, the constant presence of these two species associated with a high longevity (parous rate up around 80% and 65%, respectively), suggests that transmission can occur at almost any time if parasite reservoirs are reintroduced in the area. The proper management of malaria cases and population movement is, therefore, important to prevent outbreaks and the reintroduction of malaria in northern Vietnam. In the study site of the Mekong delta, An. sundaicus occurred at high densities (up to 190 bites/man/night). The recent changes in land use from rice cultivation to shrimp farming probably explains the increase of this brackish water breeding species during the study period. However, none of the 11 002 specimens was positive for Plasmodium circumsporozoite protein (CSP). The relative low survival rate as estimated by the parous rate (around 47 %) may reflect its low vectorial status that could explain the very low malaria incidence (1.9 case/100 persons/year) in this study site. A calculated sporozoite rate of maximum 1/300 000 is enough to explain this low malaria incidence. Despite the successes in malaria control, the vector An. dirus A continues to play an important role in malaria transmission, whereas An. minimus A showed temporal and spatial variation in its role as vector. The role of An. sundaicus as vector could not be confirmed because of the low incidence in the coastal study village. Other Anopheles species may be locally involved, but in the five study villages where malaria is still present they probably do not contribute significantly to malaria transmission. The study also points towards the fact that in Southeast Asia it will become increasingly difficult to incriminate Anopheles species in malaria transmission while the risk for malaria transmission still persist.

Malaria transmission dynamics at a site in northern Ghana proposed for testing malaria vaccines

Abstract: We studied the malaria transmission dynamics in Kassena Nankana district (KND), a site in northern Ghana proposed for testing malaria vaccines. Intensive mosquito sampling for 1 year using human landing catches in three micro-ecological sites (irrigated, lowland and rocky highland) yielded 18 228 mosquitoes. Anopheles gambiae s.l. and Anopheles funestus constituted 94.3% of the total collection with 76.8% captured from the irrigated communities. Other species collected but in relatively few numbers were Anopheles pharoensis (5.4%) and Anopheles rufipes (0.3%). Molecular analysis of 728 An. gambiae.s.l. identified Anopheles gambiae s.s. as the most dominant sibling species (97.7%) of the An. gambiae complex from the three ecological sites. Biting rates of the vectors (36.7 bites per man per night) were significantly higher (P<0.05) in the irrigated area than in the non-irrigated lowland (5.2) and rocky highlands (5.9). Plasmodium falciparum sporozoite rates of 7.2% (295/4075) and 7.1% (269/3773) were estimated for An. gambiae s.s. and An. funestus, respectively. Transmission was highly seasonal, and the heaviest transmission occurred from June to October. The intensity of transmission was higher for people in the irrigated communities than the non-irrigated ones. An overall annual entomological inoculation rate (EIR) of 418 infective bites was estimated in KND. There were micro-ecological variations in the EIRs, with values of 228 infective bites in the rocky highlands, 360 in the lowlands and 630 in the irrigated area. Approximately 60% of malaria transmission in KND occurred indoors during the second half of the night, peaking at daybreak between 04.00 and 06.00 hours. Vaccine trials could be conducted in this district, with timing dependent on the seasonal patterns and intensity of transmission taking into consideration the micro-geographical differences and vaccine trial objectives.

Improving malaria home treatment by training drug retailers in rural Kenya

Abstract: Recent global malaria control initiatives highlight the potential role of drug retailers to improve access to early effective malaria treatment. We report on the findings and discuss the implications of an educational programme for rural drug retailers and communities in Kenya between 1998 and 2001 in a study population of 70,000. Impact was evaluated through annual household surveys of over-the-counter (OTC) drug use and simulated retail client surveys in an early (1999) and a late (2000) implementation area. The programme achieved major improvements in drug selling practices. The proportion of OTC anti-malarial drug users receiving an adequate dose rose from 8% (n = 98) to 33% (n = 121) between 1998 and 1999 in the early implementation area. By 2001, and with the introduction of sulphadoxine pyrimethamine group drugs in accordance with national policy, this proportion rose to 64% (n = 441) across the early and late implementation areas. Overall, the proportion of shop-treated childhood fevers receiving an adequate dose of a recommended anti-malarial drug within 24 h rose from 1% (n = 681) to 28% (n = 919) by 2001. These findings strongly support the inclusion of private drug retailers in control strategies aiming to improve prompt effective treatment of malaria.

The spread of the Leu-Phe kdr mutation through Anopheles gambiae complex in Burkina Faso: genetic introgression and de novo phenomena

Abstract: During extensive sampling in Burkina Faso and other African countries, the Leu-Phe mutation producing the kdr pyrethroid resistance phenotype was reported in both Anopheles gambiae ss and A. arabiensis. This mutation was widely distributed at high frequency in the molecular S form of A. gambiae while it has been observed at a very low frequency in both the molecular M form and A. arabiensis in Burkina Faso. While the mutation in the M form is inherited through an introgression from the S form, its occurrence is a new and independent mutation event in A. arabiensis. Three nucleotides in the upstream intron of the kdr mutation differentiated A. arabiensis from A. gambiae ss and these specific nucleotides were associated with kdr mutation in A. arabiensis. Ecological divergences which facilitated the spread of the kdr mutation within the complex of A. gambiae ss in West Africa, are discussed.

Coverage, compliance and some operational issues of mass drug administration during the programme to eliminate lymphatic filariasis in Orissa, India

Abstract: This paper reports the coverage, compliance and other operational issues of mass drug administration (MDA) of diethylcarbamazine and albendazole under a programme to eliminate lymphatic filariasis (LF) in Orissa state of India. Both quantitative and qualitative methods were used to collect data from 90 villages and nine urban areas of four districts of Orissa, India. In Orissa, 67% of people older than 2 years had received the drugs during MDA and 42% had consumed them. About 25% of people had not taken the tablets although they received them. Urban areas recorded lower rates than rural areas. The paper discusses some policy/health system-, community- and drug-related issues that influenced coverage and compliance of MDA. It is essential to improve compliance in future rounds of MDA to achieve targets of control and eventual elimination of LF in a reasonable time frame.

Review: multidrug-resistant tuberculosis: public health challenges.

Abstract: Recently the traditional terms ‘acquired drug resistance’ and ‘primary drug resistance’ have been superseded by the terms ‘drug resistance among new cases’ as a proxy of primary resistance and ‘drug resistance among previously treated cases’ as a proxy of acquired resistance. The reason for this is that patients may not disclose prior treatment for tuberculosis (which would have led to the term ‘primary drug resistance’ being erroneously used). Alternatively patients may fail treatment because their strain was resistant from the start and not because it acquired resistance as a consequence of treatment (which would have led to the term ‘acquired drug resistance’ being applied inappropriately). The purpose of this paper is to describe some of the public health challenges many of which are formidable facing those involved in countering the threat posed by MDRTB (multi-drug-resistant tuberculosis). (excerpt)

Effectiveness of intermittent preventive treatment with sulphadoxine‐pyrimethamine for control of malaria in pregnancy in western Kenya: a hospital‐based study

Abstract: To monitor the effectiveness of intermittent preventive treatment (IPT) with sulphadoxinepyrimethamine (SP) for the control of malaria in pregnancy at delivery in the Provincial Hospital in Kisumu Kenya and to assess the effect of IPT in participants in a cohort study. Between June 1999 and June 2000 information on IPT and birth outcome was collected in 2302 consecutive deliveries. A group of 889 women who were enrolled in a cohort to assess the interaction between malaria and HIV were analysed separately because of the enrolment criteria and different access to health care. The prevalence of placental malaria was 13.8% and of low birthweight (LBW) was 12.2%. In multivariable analysis IPT (=1 dose of SP) was associated with a reduction in placental malaria and LBW [adjusted odds ratio (OR) 0.56 95% confidence interval (CI) 0.39–0.83 and OR 0.65 95% CI 0.45–0.95 respectively]. An adjusted mean increase in birthweight of 61 g was seen (95% CI 22–101 g) for each increment in number of SP doses (=2 doses grouped together). IPT was associated with a reduction in placental malaria in HIV-seronegative women (OR 0.49 95% CI 0.28–0.86) but this was not significant among HIV-seropositive women (OR 0.45 95% CI 0.20–1.05). A significant effect on birthweight could not be detected among participants in the HIV-cohort. This evaluation confirms that IPT with SP is effective in reducing placental malaria and LBW. It will be important to increase coverage of IPT and to extend IPT to antenatal clinics in peri-urban and rural areas. (authors)

Predominance of lineage I among Trypanosoma cruzi isolates from Venezuelan patients with different clinical profiles of acute Chagas' disease.

Abstract: Trypanosoma cruzi isolates from 23 acute chagasic patients from localities of Western Venezuela (state of Barinas) where Chagas' disease is endemic were typed using ribosomal and mini-exon gene markers. Results showed that isolates of the two major phylogenetic lineages, T. cruzi I and T. cruzi II, were isolated from these patients. Six isolates (26%) were typed as T. cruzi II and 17 (74%) as belonging to T. cruzi lineage I. Analysis of random amplified polymorphic DNA (RAPD) patterns confirmed these two groups of isolates, but did not disclose significant genetic intra-lineage polymorphism. Patients infected by both T. cruzi I or T. cruzi II showed different clinical profiles presenting highly variable signs and symptoms of acute phase of Chagas' disease ranging from totally asymptomatic to severe heart failure. The predominance of T. cruzi I human isolates in Venezuela allied to the higher prevalence of severe symptoms of Chagas' disease (heart failure) in patients infected by this lineage do not corroborate an innocuousness of T. cruzi I infection to humans. To our knowledge, this is the first study describing predominance of T. cruzi lineage I in a large number of acute chagasic patients with distinct and well-characterized clinical profiles.

Indirect costs associated with accessing eye care services as a barrier to service use in Ethiopia

Abstract: BACKGROUND The prevalence of blindness and visual impairment are high in Ethiopia and use of services is limited. Determining the barriers to use of eye care services is critical for planning strategies to prevent blindness. METHODS A population-based survey of the magnitude and causes of blindness and visual impairment in adults 40 years and older in the Gurage Zone, central Ethiopia was conducted. Among those individuals who had binocular or monocular vision <6/18, an interview to assess use of eye care services and reasons for a failure to use such services was undertaken. RESULTS Of 850 adults with visual impairment or blindness, 802 were interviewed. Cataract surgery accounted for the primary service currently needed by the blind, followed by trichiasis surgery; service needs were higher for women than for men. Use of services (27.8% of sample) was associated with being male, binocular vision loss, and blindness. The primary reason for a failure to use eye care services were indirect costs (overall, reported by 40% of respondents) associated with accessing the service. There were significant differences between men and women in the reasons for not using the services and between cataract and trichiasis cases but not when comparing binocular vs. monocular conditions, or patients with visual impairment vs. blindness. CONCLUSION The majority of the causes of visual impairment and blindness are treatable (cataract) or preventable (trachomatous trichiasis). The main barrier for seeking service is related to the indirect medical costs of the service. This suggests that efforts are needed to create mechanisms that 'bridge' communities and eye care facilities. A holistic approach that deals both with the organization of services and the sociocultural factors in communities that affect use is needed. The organization of trichiasis surgery at peripheral health centres and screening programmes which identify and facilitate transport to hospital for cataract patients is one approach. The indirect burden of accessing eye care on the family may be lessened by encouraging patients to have surgery earlier (before they require assistance to reach the hospital), and by improving the efficiency of existing services. Promotion of services must be gender-sensitive, ensuring that specific characteristics of the sociocultural roles of women be considered in order to improve uptake among women. Training and placement of cataract surgeons in rural hospitals would also enhance provision of eye care for the rural population.

Does increased general schooling protect against HIV infection? A study in four African cities.

Abstract: BACKGROUND: The association between educational attainment and risk of HIV infection varies between populations and over time. Earlier studies in sub-Saharan Africa have found that those with more education are at increased risk of HIV infection. METHODS: We investigated the associations between general schooling and both HIV and herpes simplex-2 (HSV-2) infection using data from the multicentre study on factors determining the differential spread of HIV in four African cities. Cross-sectional general population studies were conducted in 1997-1998 in Cotonou (Benin), Yaounde (Cameroon), Kisumu (Kenya), and Ndola (Zambia), including about 2000 adults in each city. RESULTS: There was no association between schooling and HIV infection in men or women in Kisumu or Ndola. Women in Yaounde and men in Cotonou, with more schooling, were less likely to be HIV positive. These associations persisted after adjusting for sociodemographic factors. Similar trends in men in Yaounde and women in Cotonou were not statistically significant. Increased schooling was associated with significantly decreased risk of HSV-2 infection in women in Kisumu and Ndola and men in Cotonou. In all the cities those with more education tended to report less risky sexual behaviour. CONCLUSIONS: There was no evidence of an increased risk of HIV infection associated with education as seen in earlier studies. In each city there was some evidence of lower HIV or HSV-2 infection rates and less risky sexual behaviour associated with increased education levels. The most educated may be responding more readily to health education programmes. The challenge is to extend this to the rest of the population.

Tuberculosis control in resource‐poor countries: have we reached the limits of the universal paradigm?

Abstract: The aim of TB control is to break the cycle of transmission by treating TB cases as early and efficiently as possible. In its efforts to promote a model of worldwide TB control, WHO defined specific targets and launched the 'Directly Observed Therapy, Short-course' (DOTS) strategy as the main tool to reach them. However, the diversity of patients' attitudes towards the disease and the extreme variability of access to care, especially in resource-poor countries, are amongst the many factors of social context that profoundly affect the ability of control programmes to implement this policy effectively. There are multiple reports of TB control programmes using various types of intervention to promote adherence and enhance case-holding, but most of these interventions depend on external funding, which bring into question their long-term sustainability. In this paper, we address the problems related to operational variabilities in the implementation of the DOTS strategy in resource-poor countries and question the appropriateness of a universal paradigm for global TB control. This analysis is of particular importance as programmers consider using this model in the delivery of anti-retroviral therapies for the treatment of HIV in resource-limited settings.

Editorial: Household water management: refining the dominant paradigm

Abstract: Diarrhoeal diseases kill an estimated 2.5 million people each year, the majority being children under 5 years (Kosek et al. 2003). An estimated 4 billion cases annually account for 5.7% of the global burden of disease and place diarrhoeal disease as the third highest cause of morbidity and sixth highest cause of mortality (Pruess et al. 2002). Among children under 5 years in developing countries, diarrhoeal disease accounts for 21% of all deaths (Parashar et al. 2003). By inhibiting normal consumption of foods and adsorption of nutrients, diarrhoeal diseases are also an important cause of malnutrition, leading to impaired physical growth and cognitive development (Guerrant et al. 1999), reduced resistance to infection (Baqui et al. 1993) and potentially long-term gastrointestinal disorders (Schneider et al. 1978). Infectious agents associated with diarrhoeal disease are transmitted chiefly through the faecal-oral route (Byers et al. 2001). A wide variety of bacterial, viral and protozoan pathogens excreted in the faeces of humans and animals are known to cause diarrhoea. Many of these are potentially waterborne – transmitted through the ingestion of contaminated water (Leclerc et al. 2002). Accordingly, a number of interventions have been developed to treat water. These include (i) physical removal of pathogens (e.g. filtration, adsorption and sedimentation); (ii) chemical treatment (e.g. assisted sedimentation, chemical disinfection and ion exchange); or (iii) heat and ultra violet (UV) radiation. Because of the risk of recontamination (Clasen & Bastable 2003), interventions to improve water quality also include steps to maintain the microbiological quality of safe drinking water, such as piped distribution, residual disinfection and improved storage. These efforts are expected to receive additional priority as a result of the United Nation’s commitment to reduce by one-half of the 1.5 billion people without sustainable access to improved water, one of the United Nation’s Millennium Development Goals (United Nations 2000), and by the World Health Organization’s steps to accelerate the health gains of safe water to the remaining population by improved treatment and storage of water at the household level (Sobsey 2002). Health authorities generally accept that safe water plays an important role in preventing outbreaks of diarrhoeal disease (Hunter 1997). Accordingly, the most widely accepted standard for water quality allows no detectable level of harmful pathogens at the point of distribution (WHO 1993). However, in those settings in which diarrhoeal disease is endemic, much of the epidemiological evidence for increased health benefits following improvements in the quality of drinking water has been equivocal (Esrey & Habicht 1986; Lindskog et al. 1987; Cairncross 1989). As many of these same waterborne pathogens are also transmitted via ingestion of contaminated food and other beverages, by person-to-person contact, and by direct or indirect contact with infected faeces, improvements in water quality alone may not necessarily interrupt transmission (Briscoe 1984). As a result of this variety of risk factors, interventions for the prevention of diarrhoeal disease not only include enhanced water quality but also steps to (i) improve the proper disposal of human faeces (sanitation), (ii) increase the quantity and improve access to water (water supply), and (iii) promote hand washing and other hygiene practices within domestic and community settings (hygiene). As in the case of studies of water quality, there is a wide range in the reported measure of effect on diarrhoea morbidity of each of these other environmental interventions (Esrey et al. 1985). Even more fundamentally, there are also questions about the methods and validity of studies designed to assess the health impact of such interventions (Briscoe et al. 1986; Imo State Evaluation Team 1989). As part of a larger evaluation of interventions for the control of diarrhoeal disease (Feachem et al. 1983), Esrey et al. (1985) reviewed 67 studies to determine the health impact from improvements in water supplies and excreta disposal facilities (Esrey et al. 1985). The median reduction in diarrhoeal morbidity from improved water quality was 16% (range 0–90%). This compared with 22% for Tropical Medicine and International Health

Retail supply of malaria-related drugs in rural Tanzania: risks and opportunities

Abstract: OBJECTIVES To characterize availability of fever and malaria medicines within the retail sector in rural Tanzania, assess the likely public health implications, and identify opportunities for policy interventions to increase the coverage of effective treatment. METHODS A census of retailers selling drugs was undertaken in the areas under demographic surveillance in four Tanzanian districts, using a structured questionnaire. RESULTS Drugs were stocked by two types of retailer: a large number of general retailers (n = 675) and a relatively small number of drug shops (n = 43). Almost all outlets stocked antipyretics/painkillers. One-third of general retailers stocking drugs had antimalarials, usually chloroquine alone. Almost all drug shops stocked antimalarials (98%): nearly all had chloroquine, 42% stocked quinine, 37% sulphadoxine-pyrimethamine and 30% amodiaquine. A large number of antimalarial brands were available. Population ratios indicate the relative accessibility of retail drug providers compared with health facilities. Drug shop staff generally travelled long distances to buy from drugs wholesalers or pharmacies. General retailers bought mainly from local general wholesalers, with a few general wholesalers accounting for a high proportion of all sources cited. CONCLUSIONS Drugs were widely available from a large number of retail outlets. Potential negative implications include provision of ineffective drugs, confusion over brand names, uncontrolled use of antimalarials, and the availability of components of potential combination therapy regimens as monotherapies. On the other hand, this active and highly accessible retail market provides opportunities for improving the coverage of effective antimalarial treatment. Interventions targeted at all drug retailers are likely to be costly to deliver and difficult to sustain, but two promising points for targeted intervention are drug shops and selected general wholesalers. Retail quality may also be improved through consumer education, and modification of the chemical quality, packaging and price of products entering the retail distribution chain.

The effectiveness of active population screening and treatment for sleeping sickness control in the Democratic Republic of Congo

Abstract: BACKGROUND The human African trypanosomiasis (HAT) control programme of the Democratic Republic of Congo (DRC) uses mass screening with the card agglutination test for trypanosomes (CATT). We looked at the contribution of CATT and improved parasitological confirmation to the effectiveness of screening and treatment. METHOD The effectiveness of the screening and treatment process is measured by the percentage of HAT cases that is effectively cured after a single round of screening. The process is analysed in five steps: (i) the attendance at the screening, (ii) the sensitivity of the screening procedure, (iii) the sensitivity of the parasitological confirmation, (iv) the proportion of the confirmed cases that effectively receive treatment and (v) the cure rate of the treatment. We used a simplified model that multiplies proportions of infected persons that go through each step. We estimated these parameters using a combination of routine data collected by the national control programme over the period January 1997 to December 1998 and published data. For varying attendance rates we compared the effectiveness of screening strategies based on CATT or on CATT combined with improved parasitological confirmation by mini anion exchange column technique (mAECT) with the previously used strategy based on palpation of neck glands and microscopy alone. RESULTS The model shows that overall effectiveness of the active case detection and treatment strategy is <50% under most scenarios. Attendance rates averaged 74% but showed considerable regional variability and are a major problem in some areas of DRC. The CATT and replacing traditional parasitology by mAECT increases the sensitivity of the screening but a substantial part of the gains are lost at other stages of the screening process. CONCLUSION Improvements of the HAT screening process such as introduction of CATT or mAECT only make sense if other parameters and attendance rate in particular are optimized at the same time.