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We believe a lack of transparency undermines both the credibility of, and interest in, stated choice studies among policy makers. Unlike articles reporting the results of contingent valuation studies, papers in the stated choice literature rarely present simple tabulations of raw response data (that is, a table or graph showing the percentage of respondents agreeing to purchase a good or service, or vote for a proposed management plan as a function of price). We describe an approach for adding "policy" tasks to a standard orthogonal-in-attribute-levels research design that allows the researcher to plot raw responses as a function of changes in only one characteristic of the offered good or service. We demonstrate this approach using data from a stated choice study of private demand for cholera and typhoid vaccines in Kolkata, India, carried out in the summer of 2004.

Background: Falciparum malaria increases the risk for bacteraemia, whereas the relationship between vivax malaria and bacteraemia is not clear. Data from a prospective fever surveillance study in Kolkata, India were reanalysed for the potential association between Plasmodium vivax malaria and bacteraemia. Methods: Patients of all ages presenting with fever of three days or more to a project health outpost were invited to participate. A blood film and blood culture was performed on presentation. Treatment and referral were provided according to national guidelines. The case fraction and incidence of malaria, bacteraemia, and co-infection were calculated. Results: 3,371 participants were enrolled during a one-year study period, of whom 93/3,371 (2.8%) had malaria (89/93 [95.7%] Plasmodium vivax) and 256 (7.6%) bacteraemia. There were 154 malaria, 423 bacteraemia and 10 P. vivax-bacteremia coinfection episodes per 100,000/year. Among the malaria-bacteraemia co-infections, all were vivax malaria and 5/6 (83%) bacteria isolated were Gram-negative (one S. Typhi, one S. Paratyphi A, three other Gram-negative). Bacteraemia occurred in 6/89 (6.7% [95%CI: 3.1-13.9%]) of P. vivax cases versus 250/3,278 (7.6% [95% CI: 6.7-8.6%]) without Plasmodium infection (p=0.76). Conclusions: While an increased risk was not demonstrated, concomitant bacteraemia occurs frequently in vivax malaria in an area with a high background incidence of bacteraemia, and should be considered in cases of vivax malaria with severe manifestations. [ABSTRACT FROM AUTHOR]

We evaluated the herd protection conferred by the bivalent killed oral cholera vaccine. The vaccine conferred significant herd protection, suggesting that significant public health impact in cholera control may be achieved even with modest vaccination coverage.Background. We evaluated the herd protection conferred by an oral cholera vaccine using 2 approaches: cluster design and geographic information system (GIS) design.Methods. Residents living in 3933 dwellings (clusters) in Kolkata, India, were cluster-randomized to receive either cholera vaccine or oral placebo. Nonpregnant residents aged ≥1 year were invited to participate in the trial. Only the first episode of cholera detected for a subject between 14 and 1095 days after a second dose was considered. In the cluster design, indirect protection was assessed by comparing the incidence of cholera among nonparticipants in vaccine clusters vs those in placebo clusters. In the GIS analysis, herd protection was assessed by evaluating association between vaccine coverage among the population residing within 250 m of the household and the occurrence of cholera in that population.Results. Among 107 347 eligible residents, 66 990 received 2 doses of either cholera vaccine or placebo. In the cluster design, the 3-year data showed significant total protection (66% protection, 95% confidence interval [CI], 50%–78%, P < .01) but no evidence of indirect protection. With the GIS approach, the risk of cholera among placebo recipients was inversely related to neighborhood-level vaccine coverage, and the trend was highly significant (P < .01). This relationship held in multivariable models that also controlled for potentially confounding demographic variables (hazard ratio, 0.94 [95% CI, .90–.98]; P < .01).Conclusions. Indirect protection was evident in analyses using the GIS approach but not the cluster design approach, likely owing to considerable transmission of cholera between clusters, which would vitiate herd protection in the cluster analyses.Clinical Trials Registration. NCT00289224. [ABSTRACT FROM PUBLISHER]

Introduction: The outbreak of cholera in Zimbabwe intensified interest in the control and prevention of cholera. While there is agreement that safe water, sanitation, and personal hygiene are ideal for the long term control of cholera, there is controversy about the role of newer approaches such as oral cholera vaccines (OCVs). In October 2009 the Strategic Advisory Group of Experts advised the World Health Organization to consider reactive vaccination campaigns in response to large cholera outbreaks. To evaluate the potential benefit of this pivotal change in WHO policy, we used existing data from cholera outbreaks to simulate the number of cholera cases preventable by reactive mass vaccination. Methods: Datasets of cholera outbreaks from three sites with varying cholera endemicity-Zimbabwe, Kolkata (India), and Zanzibar (Tanzania)-were analysed to estimate the number of cholera cases preventable under differing response times, vaccine coverage, and vaccine doses. Findings: The large cholera outbreak in Zimbabwe started in mid August 2008 and by July 2009, 98,591 cholera cases had been reported with 4,288 deaths attributed to cholera. If a rapid response had taken place and half of the population had been vaccinated once the first 400 cases had occurred, as many as 34,900 (40%) cholera cases and 1,695 deaths (40%) could have been prevented. In the sites with endemic cholera, Kolkata and Zanzibar, a significant number of cases could have been prevented but the impact would have been less dramatic. A brisk response is required for outbreaks with the majority of cases occurring during the early weeks. Even a delayed response can save a substantial number of cases and deaths in long, drawn-out outbreaks. If circumstances prevent a rapid response there are good reasons to roll out cholera mass vaccination campaigns well into the outbreak. Once a substantial proportion of a population is vaccinated, outbreaks in subsequent years may be reduced if not prevented. A single dose vaccine would be of advantage in short, small outbreaks. Conclusions: We show that reactive vaccine use can prevent cholera cases and is a rational response to cholera outbreaks in endemic and non-endemic settings. In large and long outbreaks a reactive vaccination with a two-dose vaccine can prevent a substantial proportion of cases. To make mass vaccination campaigns successful, it would be essential to agree when to implement reactive vaccination campaigns and to have a dynamic and determined response team that is familiar with the logistic challenges on standby. Most importantly, the decision makers in donor and recipient countries have to be convinced of the benefit of reactive cholera vaccinations. [ABSTRACT FROM AUTHOR]

Objective: To define mortality patterns in an urban slum in Kolkata, India, in the context of a cholera and typhoid fever project. Methods: In a well-defined population that was under surveillance for 18 months, we followed a dynamic cohort of 63 788 residents whose households were visited monthly by community health workers to identify deaths. Trained physicians performed verbal autopsies and experienced senior physicians assigned the primary cause of death according to the International classification of diseases, 10th edition. We tabulated causes of death in accordance with Global Burden of Disease 2000 categories and assessed overall and cause-specific mortality rates per age group and gender. Findings: During 87 921 person-years of follow-up, we recorded 544 deaths. This gave an overall mortality rate of 6.2 per 1000 person-years. We assigned a cause to 89% (482/544) of the deaths. The leading causes of death, in descending order, were cardiovascular diseases (especially among adults aged over 40 years), cancer, respiratory ailments and digestive disorders. Most deaths in children under 5 years of age were caused by tuberculosis, respiratory infections and diarrhoeal diseases. Conclusion: Although the most common causes of death in children were infectious, non-communicable diseases were predominant among adults. There is a need for continuing interventions against infectious diseases in addition to new and innovative strategies to combat non-infectious conditions. [ABSTRACT FROM AUTHOR]

Summary: The “old” familiar diseases of cholera and typhoid remain a serious health threat in many developing countries. Health policy analysts often argue that vaccination against cholera and typhoid should be provided free because poor people cannot afford to pay for such vaccines and because vaccination confers positive economic externalities on unvaccinated individuals. In 2004, we conducted a contingent valuation (CV) survey of 835 randomly selected adults from two neighborhoods in Kolkata, India to provide information on private demand for cholera and typhoid vaccines for themselves and for household members to support more nuanced financial and economics analyses of such vaccination programs. The median private economic benefits of providing a typhoid vaccine to a household with five members is about US$23 in a middle-income neighborhood (US$27 for a cholera vaccine) and US$14 in a low-income slum (US$15 for a cholera vaccine). Our research raises an intriguing possibility. If user charges were set at a level to recover the costs of a vaccination program, there could be sufficient demand for the vaccine so that coverage of the vaccinated population might ensure that all the remaining unvaccinated individuals would be protected as well through indirect herd protection. [Copyright &y& Elsevier]

Background: The test-negative design (TND) has emerged as a simple method for evaluating vaccine effectiveness (VE). Its utility for evaluating oral cholera vaccine (OCV) effectiveness is unknown. We examined this method's validity in assessing OCV effectiveness by comparing the results of TND analyses with those of conventional cohort analyses., Methods: Randomized controlled trials of OCV were conducted in Matlab (Bangladesh) and Kolkata (India), and an observational cohort design was used in Zanzibar (Tanzania). For all three studies, VE using the TND was estimated from the odds ratio (OR) relating vaccination status to fecal test status (Vibrio cholerae O1 positive or negative) among diarrheal patients enrolled during surveillance (VE= (1-OR)×100%). In cohort analyses of these studies, we employed the Cox proportional hazard model for estimating VE (=1-hazard ratio)×100%)., Results: OCV effectiveness estimates obtained using the TND (Matlab: 51%, 95% CI:37-62%; Kolkata: 67%, 95% CI:57-75%) were similar to the cohort analyses of these RCTs (Matlab: 52%, 95% CI:43-60% and Kolkata: 66%, 95% CI:55-74%). The TND VE estimate for the Zanzibar data was 94% (95% CI:84-98%) compared with 82% (95% CI:58-93%) in the cohort analysis. After adjusting for residual confounding in the cohort analysis of the Zanzibar study, using a bias indicator condition, we observed almost no difference in the two estimates., Conclusion: Our findings suggest that the TND is a valid approach for evaluating OCV effectiveness in routine vaccination programs., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Efficacy and safety of a two-dose regimen of bivalent killed whole-cell oral cholera vaccine (Shantha Biotechnics, Hyderabad, India) to 3 years is established, but long-term efficacy is not. We aimed to assess protective efficacy up to 5 years in a slum area of Kolkata, India., Methods: In our double-blind, cluster-randomised, placebo-controlled trial, we assessed incidence of cholera in non-pregnant individuals older than 1 year residing in 3933 dwellings (clusters) in Kolkata, India. We randomly allocated participants, by dwelling, to receive two oral doses of modified killed bivalent whole-cell cholera vaccine or heat-killed Escherichia coli K12 placebo, 14 days apart. Randomisation was done by use of a computer-generated sequence in blocks of four. The primary endpoint was prevention of episodes of culture-confirmed Vibrio cholerae O1 diarrhoea severe enough for patients to seek treatment in a health-care facility. We identified culture-confirmed cholera cases among participants seeking treatment for diarrhoea at a study clinic or government hospital between 14 days and 1825 days after receipt of the second dose. We assessed vaccine protection in a per-protocol population of participants who had completely ingested two doses of assigned study treatment., Findings: 69 of 31 932 recipients of vaccine and 219 of 34 968 recipients of placebo developed cholera during 5 year follow-up (incidence 2·2 per 1000 in the vaccine group and 6·3 per 1000 in the placebo group). Cumulative protective efficacy of the vaccine at 5 years was 65% (95% CI 52-74; p<0·0001), and point estimates by year of follow-up suggested no evidence of decline in protective efficacy., Interpretation: Sustained protection for 5 years at the level we reported has not been noted previously with other oral cholera vaccines. Established long-term efficacy of this vaccine could assist policy makers formulate rational vaccination strategies to reduce overall cholera burden in endemic settings., Funding: Bill & Melinda Gates Foundation and the governments of South Korea and Sweden., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: Despite advancement of our knowledge, cholera remains a public health concern. During March-April 2010, a large cholera outbreak afflicted the eastern part of Kolkata, India. The quantification of importance of socio-environmental factors in the risk of cholera, and the calculation of the risk is fundamental for deploying vaccination strategies. Here we investigate socio-environmental characteristics between high and low risk areas as well as the potential impact of vaccination on the spatial occurrence of the disease., Methods and Findings: The study area comprised three wards of Kolkata Municipal Corporation. A mass cholera vaccination campaign was conducted in mid-2006 as the part of a clinical trial. Cholera cases and data of the trial to identify high risk areas for cholera were analyzed. We used a generalized additive model (GAM) to detect risk areas, and to evaluate the importance of socio-environmental characteristics between high and low risk areas. During the one-year pre-vaccination and two-year post-vaccination periods, 95 and 183 cholera cases were detected in 111,882 and 121,827 study participants, respectively. The GAM model predicts that high risk areas in the west part of the study area where the outbreak largely occurred. High risk areas in both periods were characterized by poor people, use of unsafe water, and proximity to canals used as the main drainage for rain and waste water. Cholera vaccine uptake was significantly lower in the high risk areas compared to low risk areas., Conclusion: The study shows that even a parsimonious model like GAM predicts high risk areas where cholera outbreaks largely occurred. This is useful for indicating where interventions would be effective in controlling the disease risk. Data showed that vaccination decreased the risk of infection. Overall, the GAM-based risk map is useful for policymakers, especially those from countries where cholera remains to be endemic with periodic outbreaks.

Background: Killed oral cholera vaccines (OCVs) have been licensed for use in developing countries, but protection conferred by licensed OCVs beyond two years of follow-up has not been demonstrated in randomized, clinical trials., Methods/principal Findings: We conducted a cluster-randomized, placebo-controlled trial of a two-dose regimen of a low-cost killed whole cell OCV in residents 1 year of age and older living in 3,933 clusters in Kolkata, India. The primary endpoint was culture-proven Vibrio cholerae O1 diarrhea episodes severe enough to require treatment in a health care facility. Of the 66,900 fully dosed individuals (31,932 vaccinees and 34,968 placebo recipients), 38 vaccinees and 128 placebo-recipients developed cholera during three years of follow-up (protective efficacy 66%; one-sided 95%CI lower bound = 53%, p<0.001). Vaccine protection during the third year of follow-up was 65% (one-sided 95%CI lower bound = 44%, p<0.001). Significant protection was evident in the second year of follow-up in children vaccinated at ages 1-4 years and in the third year in older age groups., Conclusions/significance: The killed whole-cell OCV conferred significant protection that was evident in the second year of follow-up in young children and was sustained for at least three years in older age groups. Continued follow-up will be important to establish the vaccine's duration of protection., Trial Registration: ClinicalTrials.gov NCT00289224.

Background: Oral cholera vaccines consisting of killed whole cells have been available for many years, but they have not been used extensively in populations with endemic disease. An inexpensive, locally produced oral killed-whole-cell vaccine has been used in high-risk areas in Vietnam. To expand the use of this vaccine, it was modified to comply with WHO standards. We assessed the efficacy and safety of this modified vaccine in a population with endemic cholera., Methods: In this double-blind trial, 107 774 non-pregnant residents of Kolkata, India, aged 1 year or older, were cluster-randomised by dwelling to receive two doses of either modified killed-whole-cell cholera vaccine (n=52 212; 1966 clusters) or heat-killed Escherichia coli K12 placebo (n=55 562; 1967 clusters), both delivered orally. Randomisation was done by computer-generated sequence in blocks of four. The primary endpoint was prevention of episodes of culture-confirmed Vibrio cholerae O1 diarrhoea severe enough for the patient to seek treatment in a health-care facility. We undertook an interim, per-protocol analysis at 2 years of follow-up that included individuals who received two completely ingested doses of vaccine or placebo. We assessed first episodes of cholera that occurred between 14 days and 730 days after receipt of the second dose. This study is registered with ClinicalTrials.gov, number NCT00289224., Findings: 31 932 participants assigned to vaccine (1721 clusters) and 34 968 assigned to placebo (1757 clusters) received two doses of study treatment. There were 20 episodes of cholera in the vaccine group and 68 episodes in the placebo group (protective efficacy 67%; one-tailed 99% CI, lower bound 35%, p<0.0001). The vaccine protected individuals in age-groups 1.0-4.9 years, 5.0-14.9 years, and 15 years and older, and protective efficacy did not differ significantly between age-groups (p=0.28). We recorded no vaccine-related serious adverse events., Interpretation: This modified killed-whole-cell oral vaccine, compliant with WHO standards, is safe, provides protection against clinically significant cholera in an endemic setting, and can be used in children aged 1.0-4.9 years, who are at highest risk of developing cholera in endemic settings., Funding: Bill & Melinda Gates Foundation, Swedish International Development Cooperation Agency, Governments of South Korea, Sweden, and Kuwait.

Background: High rates of typhoid fever and the emergence of multi-drug resistant strains create a need for prevention efforts including vaccines. Socio-behavioral research can provide important data for participation in future trials and public health vaccination campaigns., Design: A 3b phase clinical trial in Kolkata India including pre- and post-vaccination socio-behavioral surveys., Results: 47.9% of respondents were male. Ward 29 respondents included 32.4% Hindu and Ward 30 respondents were 99.0% Hindu. Lower rates of participation were found among Muslim respondents and those with post high school education. Lack of information and negative information affected participation. Joint decision-making within households increased participation rates., Methods: seven hundred households were randomly selected 503 respondents (71.85%) completed both the pre- and post-closed-ended surveys. Data analysis included descriptive statistics, Pearson's chi-square tests, independent t-tests, and stepwise logistic regression analysis. Four open-ended questions were included in the survey. These qualitative data were coded and reviewed for common themes and patterns., Conclusions: Individuals' decisions to participate or not participate in a vaccine trial entail a balance between individual beliefs, household dynamics and socio-political influences. Efforts prior to vaccination trials need to develop strategies which address potential underlying mediators for belief systems as well as structural factors which may reinforce individuals' beliefs and perceptions about vaccination trials.

Objectives: An effective vaccine against cholera has been used for public health purposes in Vietnam since the 1990s. This vaccine was reformulated to meet WHO requirements. We assessed the safety and immunogenicity of the reformulated bivalent (Vibrio cholerae 01 and 0139) killed whole cell oral vaccine in a cholera endemic area in Kolkata, India., Design: Double-blind, randomized, placebo controlled trial., Setting: The trial was conducted in the clinical trial ward of the Infectious Diseases Hospital in Kolkata, India., Participants: The participants were 101 healthy adults (males and non-pregnant females) aged 18-40 years and 100 healthy children (males and non-pregnant females) aged 1-17 years., Interventions: Participants were randomized to receive either the bivalent killed whole cell oral cholera vaccine or placebo (killed oral Escherichia coli K12)., Outcome Measures: For safety: proportion of subjects with adverse events during the duration of study participation. For immunogenicity: Proportion of subjects who had a > or = 4-fold rise in serum vibriocidal antibody titers 14 days after the second dose of vaccine or placebo., Results: Adverse reactions were observed with similar frequency among vaccine and placebo recipients in both age groups. Among adults 4% of vaccine and 8% of placebo recipients and among children 4% of vaccine and 2% of placebo recipients had at least one adverse event within 28 days of the first dose of the vaccine. Following immunization, 53% of adult and 80% of children vaccinees showed a > or = 4 fold rise in serum V. cholerae O1 vibriocidal antibody titers. A less pronounced response to V. cholerae O139 vibriocidal antibody titers post-immunization was noted among vaccinees., Conclusions: We found the vaccine to be safe and immunogenic in a cholera-endemic area in India., Trial Registration: ClinicalTrials.gov NCT00119197.

Background: Exposure of the individual to contaminated food or water correlates closely with the risk for enteric fever. Since public health interventions such as water improvement or vaccination campaigns are implemented for groups of individuals we were interested whether risk factors not only for the individual but for households, neighbourhoods and larger areas can be recognised?, Methods: We conducted a large enteric fever surveillance study and analyzed factors which correlate with enteric fever on an individual level and factors associated with high and low risk areas with enteric fever incidence. Individual level data were linked to a population based geographic information systems. Individual and household level variables were fitted in Generalized Estimating Equations (GEE) with the logit link function to take into account the likelihood that household factors correlated within household members., Results: Over a 12-month period 80 typhoid fever cases and 47 paratyphoid fever cases were detected among 56,946 residents in two bustees (slums) of Kolkata, India. The incidence of paratyphoid fever was lower (0.8/1000/year), and the mean age of paratyphoid patients was older (17.1 years) than for typhoid fever (incidence 1.4/1000/year, mean age 14.7 years). Residents in areas with a high risk for typhoid fever had lower literacy rates and economic status, bigger household size, and resided closer to waterbodies and study treatment centers than residents in low risk areas., Conclusion: There was a close correlation between the characteristics detected based on individual cases and characteristics associated with high incidence areas. Because the comparison of risk factors of populations living in high versus low risk areas is statistically very powerful this methodology holds promise to detect risk factors associated with diseases using geographic information systems.

Although typhoid fever is confirmed by culture of Salmonella enterica serotype Typhi, rapid and simple diagnostic serologic tests would be useful in developing countries. We examined the performance of Widal test in a community field site and compared it with Typhidot and Tubex tests for diagnosis of typhoid fever. Blood samples were collected from 6697 patients with fever for > or =3 days for microscopy, culture, and serologic testing and from randomly selected 172 consenting healthy individuals to assess the baseline Widal anti-Typhi O lipopolysaccharide antibody (anti-TO) and anti-Typhi H flagellar antibody (anti-TH) titers. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the 3 serologic tests were calculated using culture-confirmed typhoid fever cases as "true positives" and paratyphoid fever and malaria cases as "true negatives". Comparing cutoff values for the Widal test, an anti-TO titer of 1/80 was optimal with 58% sensitivity, 85% specificity, 69% PPV, and 77% NPV. Sensitivity was increased to 67% when the Widal test was done on the 5th day of illness and thereafter. The sensitivity, specificity, PPV, and NPV of Typhidot and Tubex were not better than Widal test. There is a need for more efficient rapid diagnostic test for typhoid fever especially during the acute stage of the disease. Until then, culture remains the method of choice.

Recent research has indicated that the malaria burden in Asia may have been vastly underestimated. We conducted a prospective community-based study in an impoverished urban site in Kolkata, India, to estimate the burden of malaria and typhoid fever and to identify risk factors for these diseases. In a population of 60452 people, 3605 fever episodes were detected over a 12-month period. The blood films of 93 febrile patients contained Plasmodium (90 P. vivax, 2 P. falciparum and 1 P. malariae). Blood cultures from 95 patients grew Salmonella enterica serotype Typhi. Malaria patients were found to be significantly older (mean age 29 years) compared with patients with typhoid fever (15 years; P<0.001) but had similar clinical features on presentation. Having a household member with malaria, illiteracy, low household income and living in a structure not built of bricks were associated with an increased risk for malaria. Having a household member with typhoid fever and poor hygiene were associated with typhoid fever. A geographic analysis of the spatial distribution of malaria and typhoid fever cases detected high-risk neighbourhoods for each disease. Focal interventions to minimise human-vector contact and improved personal hygiene and targeted vaccination campaigns could help to prevent malaria and typhoid fever in this site.

In an urban slum in eastern Kolkata, India, reported diarrhoea rates, healthcare-use patterns, and factors associated with reported diarrhoea episodes were studied as a part of a diarrhoea-surveillance project. Data were collected through a structured interview during a census and healthcare-use survey of an urban slum population in Kolkata. Several variables were analyzed, including (a) individual demographics, such as age and educational level, (b) household characteristics, such as number of household members, religious affiliation of the household head, building material, expenditure, water supply and sanitation, and (c) behaviour, such as hand-washing after defecation and healthcare use. Of 57,099 study subjects, 428 (0.7%) reported a diarrhoea episode sometime during the four weeks preceding the interview. The strongest independent factors for reporting a history of diarrhoea were having another household member with diarrhoea (adjusted odds ratio [OR]=3.8; 95% confidence interval [CI] 3.3-4.4) and age less than 60 months (adjusted OR=3.7; 95% CI 3.0-4.7). The first choice of treatment by the 428 subjects was as follows: 151 (35%) had self- or parent-treatment, 150 (35%) consulted a private allopathic practitioner, 70 (16%) went directly to a pharmacy, 29 (7%) visited a hospital, 14 (3%) a homoeopathic practitioner, 2 (0.5%) an ayurvedic practitioner, and 12 (3%) other traditional healers. The choices varied significantly with the age of patients and their religion. The findings increase the understanding of the factors and healthcare-use patterns associated with diarrhoea episodes and may assist in developing public-health messages and infrastructure in Kolkata.