Associations between presence of handwashing stations and soap in the home and diarrhoea and respiratory illness, in children less than five years old in rural western Kenya.

OBJECTIVE: We tested whether soap presence in the home or a designated handwashing station was associated with diarrhoea and respiratory illness in Kenya. METHODS: In April 2009, we observed presence of a handwashing station and soap in households participating in a longitudinal health surveillance system in rural Kenya. Diarrhoea and acute respiratory illness (ARI) in children < 5 years old were identified using parent-reported syndromic surveillance collected January-April 2009. We used multivariate generalised linear regression to estimate differences in prevalence of illness between households with and without the presence of soap in the home and a handwashing station. RESULTS: Among 2547 children, prevalence of diarrhoea and ARI was 2.3 and 11.4 days per 100 child-days, respectively. Soap was observed in 97% of households. Children in households with soap had 1.3 fewer days of diarrhoea/100 child-days (95% CI -2.6, -0.1) than children in households without soap. ARI prevalence was not associated with presence of soap. A handwashing station was identified in 1.4% of households and was not associated with a difference in diarrhoea or ARI prevalence. CONCLUSIONS: Soap presence in the home was significantly associated with reduced diarrhoea, but not ARI, in children in rural western Kenya. Whereas most households had soap in the home, almost none had a designated handwashing station, which may prevent handwashing at key times of hand contamination.

Impact of neighborhood biomass cooking patterns on episodic high indoor particulate matter concentrations in clean fuel homes in Dhaka, Bangladesh.

Exposure to particulate matter (PM2.5 ) from the burning of biomass is associated with increased risk of respiratory disease. In Dhaka, Bangladesh, households that do not burn biomass often still experience high concentrations of PM2.5 , but the sources remain unexplained. We characterized the diurnal variation in the concentrations of PM2.5 in 257 households and compared the risk of experiencing high PM2.5 concentrations in biomass and non-biomass users. Indoor PM2.5 concentrations were estimated every minute over 24 h once a month from April 2009 through April 2010. We found that households that used gas or electricity experienced PM2.5 concentrations exceeding 1000 µg/m(3) for a mean of 35 min within a 24-h period compared with 66 min in biomass-burning households. In both households that used biomass and those that had no obvious source of particulate matter, the probability of PM2.5 exceeding 1000 µg/m(3) were highest during distinct morning, afternoon, and evening periods. In such densely populated settings, indoor pollution in clean fuel households may be determined by biomass used by neighbors, with the highest risk of exposure occurring during cooking periods. Community interventions to reduce biomass use may reduce exposure to high concentrations of PM2.5 in both biomass and non-biomass using households.

Indoor exposure to particulate matter and the incidence of acute lower respiratory infections among children: a birth cohort study in urban Bangladesh.

Approximately half of all children under two years of age in Bangladesh suffer from an acute lower respiratory infection (ALRI) each year. Exposure to indoor biomass smoke has been consistently associated with an increased risk of ALRI in young children. Our aim was to estimate the effect of indoor exposure to particulate matter (PM2.5 ) on the incidence of ALRI among children in a low-income, urban community in Bangladesh. We followed 257 children through two years of age to determine their frequency of ALRI and measured the PM2.5 concentrations in their sleeping space. Poisson regression was used to estimate the association between ALRI and the number of hours per day that PM2.5 concentrations exceeded 100 µg/m(3) , adjusting for known confounders. Each hour that PM2.5 concentrations exceeded 100 µg/m(3) was associated with a 7% increase in incidence of ALRI among children aged 0-11 months (adjusted incidence rate ratio (IRR) 1.07, 95% CI 1.01-1.14), but not in children 12-23 months old (adjusted IRR 1.00, 95% CI 0.92-1.09). Results from this study suggest that reducing indoor PM2.5 exposure could decrease the frequency of ALRI among infants, the children at highest risk of death from these infections.

Community perceptions of bloody diarrhoea in an urban slum in South Asia: implications for introduction of a Shigella vaccine.

Understanding local perceptions of disease causation could help public health officials improve strategies to prevent bloody diarrhoea. A cross-sectional survey was conducted in Dhaka, Bangladesh to elicit community beliefs about the causes of and prevention strategies for bloody diarrhoea. Between March and June 2003, we interviewed 541 randomly selected respondents. Overall, 507 (93%) respondents perceived that a vaccine could prevent bloody diarrhoea. If a vaccine provided lifetime protection, 445 (83%) respondents stated that they would opt to get the vaccine and would pay a median of $0·05 (range U.S.$0·01-0·15) for it, equivalent to <1% of their median weekly income. There was almost universal perception that an effective vaccine to prevent bloody diarrhoea was highly beneficial and acceptable. While respondents valued a vaccine for prevention of bloody diarrhoea, they were only willing to pay minimally for it. Therefore, achieving a high rate of Shigella vaccine coverage may require subsidy of vaccine purchase.

International foodborne outbreak of Shigella sonnei infection in airline passengers.

During 22-24 August 2004, an outbreak of Shigella sonnei infection affected air travellers who departed from Hawaii. Forty-seven passengers with culture-confirmed shigellosis and 116 probable cases who travelled on 12 flights dispersed to Japan, Australia, 22 US states, and American Samoa. All flights were served by one caterer. Pulsed-field gel electrophoresis of all 29 S. sonnei isolates yielded patterns that matched within one band. Food histories and menu reviews identified raw carrot served onboard as the likely vehicle of infection. Attack rates for diarrhoea on three surveyed flights with confirmed cases were 54% (110/204), 32% (20/63), and 12% (8/67). A total of 2700 meals were served on flights with confirmed cases; using attack rates observed on surveyed flights, we estimated that 300-1500 passengers were infected. This outbreak illustrates the risk of rapid, global spread of illness from a point-source at a major airline hub.

Tubewell water quality and predictors of contamination in three flood-prone areas in Bangladesh.

AIMS: To measure enteric bacterial contamination of tubewells in three flood prone areas in Bangladesh and the relationship of bacteriological contamination with tubewell sanitary inspection scores. METHODS AND RESULTS: Microbiologists selected 207 tubewells in three flood prone districts, assessed physical characteristics of the tubewells and collected a single water sample from each tubewell. Tubewell water samples were contaminated with total coliforms (41%, n = 85), thermotolerant coliforms (29%, n = 60) and Escherichia coli (13%, n = 27). Among contaminated wells, the median CFU of contamination per 100 ml was 8 (interquartile range, 2-30) total coliforms, 5 (interquartile range, 2-23) thermotolerant coliforms and 6 (interquartile range, 1-30) E. coli. There was no significant association between tubewell contamination with E. coli, thermotolerant coliforms or total coliforms and a poor sanitary inspection score, though a history of inundation was associated with contamination with both E. coli and thermotolerant coliforms. CONCLUSIONS: Tubewells in flood-prone regions of Bangladesh were commonly contaminated with low levels of faecal organisms, contamination that could not be predicted by examining the tubewell's external characteristics. SIGNIFICANCE AND IMPACT OF THE STUDY: The forms currently used for sanitary inspection do not identify the most important causes of drinking water contamination in these communities.

Part I. Analysis of data gaps pertaining to Salmonella enterica serotype Typhi infections in low and medium human development index countries, 1984-2005.

There are only 10 contemporary, population-based studies of typhoid fever that evaluate disease incidence using blood culture for confirmation of cases. Reported incidence ranged from 13 to 976/100 000 persons per year. These studies are likely to have been done preferentially in high- incidence sites which makes generalization of data difficult. Only five of these studies reported mortality. Of these the median (range) mortality was 0% (0-1.8%). Since study conditions usually involved enhanced clinical management of patients and the studies were not designed to evaluate mortality as an outcome, their usefulness for generalizing case-fatality rates is uncertain. No contemporary population-based studies reported rates of complications. Hospital-based typhoid fever studies reported median (range) complication rates of 2.8% (0.6-4.9%) for intestinal perforation and case-fatality rates of 2.0% (0-14.8%). Rates of complications other than intestinal perforation were not reported in contemporary hospital-based studies. Hospital-based studies capture information on the most severe illnesses among persons who have access to health-care services limiting their generalizability. Only two studies have informed the current understanding of typhoid fever age distribution curves. Extrapolation from population-based studies suggests that most typhoid fever occurs among young children in Asia. To reduce gaps in the current understanding of typhoid fever incidence, complications, and case-fatality rate, large population-based studies using blood culture confirmation of cases are needed in representative sites, especially in low and medium human development index countries outside Asia.

Part III. Analysis of data gaps pertaining to enterotoxigenic Escherichia coli infections in low and medium human development index countries, 1984-2005.

Enterotoxigenic Escherichia coli (ETEC) is a common cause of profuse watery diarrhoea in the developing world, often leading to severe dehydration or death. We found only 15 population-based studies in low and medium human development index (HDI) countries from 1984 to 2005 that evaluate disease incidence. Reported incidence ranged from 39 to 4460 infections/1000 persons per year. The peak incidence of ETEC appeared to occur between ages 6 and 18 months. A median of 14% (range 2-36%) of diarrhoeal specimens were positive for ETEC in 19 facility- and population-based studies conducted in all age groups and 13% (range 3-39%) in 51 studies conducted in children only. Heat-labile toxin (LT)-ETEC is thought to be less likely to cause disease than heat-stable toxin (ST)-ETEC or LT/ST-ETEC. Because population-based studies involve enhanced clinical management of patients and facility-based studies include only the most severe illnesses, reliable data on complications and mortality from ETEC infections was unavailable. To reduce gaps in the current understanding of ETEC incidence, complications and mortality, large population-based studies combined with facility-based studies covering a majority of the corresponding population are needed, especially in low-HDI countries. Moreover, a standard molecular definition of ETEC infection is needed to be able to compare results across study sites.

Part II. Analysis of data gaps pertaining to Shigella infections in low and medium human development index countries, 1984-2005.

The global incidence of Shigella infection has been estimated at 80-165 million episodes annually, with 99% of episodes occurring in the developing world. To identify contemporary gaps in the understanding of the global epidemiology of shigellosis, we conducted a review of the English-language scientific literature from 1984 to 2005, restricting the search to low and medium human development countries. Our review yielded 11 population-based studies of Shigella burden from seven countries. No population-based studies have been conducted in sub-Saharan Africa or in low human development countries. In studies done in all age groups, Shigella incidence varied from 0.6 to 107 episodes/1000 person-years. S. flexneri was the most commonly detected subgroup in the majority of studies. Case-fatality rates ranged from 0% to 2.6% in population-based studies and from 0% to 21% in facility-based studies. This review highlights the large gaps in data on the burden of Shigella infections for low human development index countries and, more specifically, for sub-Saharan Africa.

Usefulness of the hydrogen sulfide test for assessment of water quality in Bangladesh.

AIM: To evaluate the usefulness of the hydrogen sulfide (H(2)S) test for assessing water quality in Bangladesh. METHODS AND RESULTS: We tested 382 water samples from a variety of sources using locally produced H(2)S test kits and laboratory-based membrane filtration for the detection of Escherichia coli. Compared with membrane filtration, H(2)S tests, when incubated for 24 h, had both a sensitivity and positive predictive value (PPV) of <40% when analysis was restricted to water samples with E. coli levels below 100 colony forming units (CFU) per 100 ml. In contrast, for E. coli levels from 1000 to 9999 CFU per 100 ml, sensitivity was 94% and PPV 88%; specificity was 97% and negative predictive value was 99%. CONCLUSIONS: The hydrogen sulfide test, when incubated at 24 h, is a promising alternative for assessing water quality where E. coli levels may be high. An improved understanding of the incremental impact of contamination level on health is needed to better determine its usefulness. SIGNIFICANCE AND IMPACT OF THE STUDY: The hydrogen sulfide test is inexpensive, easy to use and portable. Its use may allow rapid assessment of water quality in situations where cost or logistics prevent use of other testing methods, such as in remote areas or during flood and other natural disasters.

Risk factors for typhoid fever in a slum in Dhaka, Bangladesh.

We systematically investigated risk factors for typhoid fever in Kamalapur, a poor urban area of Bangladesh, to inform targeted public health measures for its control. We interviewed patients with typhoid fever and two age-matched controls per case about exposures during the 14 days before the onset of illness. The municipal water supply was used by all 41 cases and 81of 82 controls. In multivariate analysis, drinking unboiled water at home was a significant risk factor [adjusted odds ratio (aOR) 12.1, 95% CI 2.2-65.6]. Twenty-three (56%) cases and 21 (26%) controls reported that water from the primary source was foul-smelling (aOR 7.4, 95% CI 2.1-25.4). Eating papaya was associated with illness (aOR 5.2, 95% CI 1.2-22.2). Using a latrine for defecation was significantly protective (aOR 0.1, 95% CI 0.02-0.9). Improved chlorination of the municipal water supply or disinfecting drinking water at the household level may dramatically reduce the risk of typhoid fever in Kamalapur. The protective effect of using latrines, particularly among young children, should be investigated further.