P. K. Ram

Is Structured Observation a Valid Technique to Measure Handwashing Behavior? Use of Acceleration Sensors Embedded in Soap to Assess Reactivity to Structured Observation

Structured observation is often used to evaluate handwashing behavior. We assessed reactivity to structured observation in rural Bangladesh by distributing soap containing acceleration sensors and performing structured observation 4 days later. Sensors recorded the number of times soap was moved. In 45 participating households, the median number of sensor soap movements during the 5-hour time block on pre-observation days was 3.7 (range 0.3-10.6). During the structured observation, the median number of sensor soap movements was 5.0 (range 0-18.0), a 35% increase, P = 0.0004. Compared with the same 5-hour time block on pre-observation days, the number of sensor soap movements increased during structured observation by ≥ 20% in 62% of households, and by ≥ 100% in 22% of households. The increase in sensor soap movements during structured observation, compared with pre-observation days, indicates substantial reactivity to the presence of the observer. These findings call into question the validity of structured observation for measurement of handwashing behavior.

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.

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.

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.

Burden of typhoid and paratyphoid fever in a densely populated urban community, Dhaka, Bangladesh

BACKGROUND We conducted blood culture surveillance to estimate the incidence of typhoid and paratyphoid fever among urban slum residents in Dhaka, Bangladesh. METHODS Between January 7, 2003 and January 6, 2004, participants were visited weekly to detect febrile illnesses. Blood cultures were obtained at the clinic from patients with fever (≥38°C). Salmonella isolates were assayed for antimicrobial susceptibility. RESULTS Forty Salmonella Typhi and eight Salmonella Paratyphi A were isolated from 961 blood cultures. The incidence of typhoid fever was 2.0 episodes/1000 person-years, with a higher incidence in children aged<5 years (10.5/1000 person-years) than in older persons (0.9/1000 person-years) (relative risk=12, 95% confidence interval (CI) 6.3-22.6). The incidence of paratyphoid fever was 0.4/1000 person-years without variation by age group. Sixteen S. Typhi isolates were multidrug-resistant (MDR). All S. Paratyphi isolates were pan-susceptible. The duration of fever among patients with an MDR S. Typhi infection was longer than among patients with non-MDR S. Typhi (16±8 vs. 11±4 days, p=0.02) and S. Paratyphi (10±2 days, p=0.04) infections. CONCLUSIONS Typhoid fever is more common than paratyphoid fever in the urban Bangladeshi slum; children<5 years old have the highest incidence. Multidrug resistance is common in S. Typhi isolates and is associated with prolonged illness. Strategies for typhoid fever prevention in children aged<5 years in Bangladesh, including immunization, are needed.

An Outbreak of Enterotoxigenic Escherichia coli Associated with Sushi Restaurants in Nevada, 2004

BACKGROUND In August and November 2004, 2 clusters of diarrhea cases occurred among patrons of 2 affiliated sushi restaurants (sushi restaurant A and sushi restaurant B) in Nevada. In August 2004, a stool sample from 1 ill sushi restaurant A patron yielded enterotoxigenic Escherichia coli (ETEC). In December 2004, we investigated a third cluster of diarrhea cases among sushi restaurant B patrons. METHODS We defined a case as diarrhea in a person who ate at sushi restaurant B from 3 December through 13 December 2004. Control subjects were individuals who dined with case patients but did not become ill. Duplex polymerase chain reaction was used to detect genes coding for heat-stable and heat-labile enterotoxins of ETEC. RESULTS One-hundred thirty patrons of sushi restaurant B reported illness; we enrolled 36 case patients and 29 control subjects. The diarrhea-to-vomiting prevalence ratio among patients was 4.5. Illness was associated with consumption of butterfly shrimp (estimated odds ratio, 7.2; 95% confidence interval, 1.1 to infinity). The implicated food was distributed to many restaurants, but only sushi restaurant B patrons reported diarrhea. We observed poor food-handling and hand hygiene practices at sushi restaurant B. Stool samples from 6 of 7 ill patrons and 2 of 27 employees who denied illness yielded ETEC. CONCLUSIONS ETEC was identified as the etiologic agent of a large foodborne outbreak at a sushi restaurant in Nevada. Poor food-handling practices and infected foodhandlers likely contributed to this outbreak. Although ETEC is a well-documented cause of domestic foodborne outbreaks, few laboratories can test for it. Earlier recognition of ETEC infections may prevent subsequent outbreaks from occurring.

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.

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.

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

Aim:  To evaluate the usefulness of the hydrogen sulfide (H2S) test for assessing water quality in Bangladesh.

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