A Game-Theoretic Model of Cholera with Optimal Personal Protection Strategies.

Cholera is an acute gastro-intestinal infection that affects millions of people throughout the world each year, primarily but not exclusively in developing countries. Because of its public health ramifications, considerable mathematical attention has been paid to the disease. Here we consider one neglected aspect of combating cholera: personal participation in anti-cholera interventions. We construct a game-theoretic model of cholera in which individuals choose whether to participate in either vaccination or clean water consumption programs under assumed costs. We find that relying upon individual compliance significantly lowers the incidence of the disease as long as the cost of intervention is sufficiently low, but does not eliminate it. The relative costs of the measures determined whether a population preferentially adopts a single preventative measure or employs the measure with the strongest early adoption.

Delivery cost analysis of a reactive mass cholera vaccination campaign: a case study of Shanchol™ vaccine use in Lake Chilwa, Malawi.

BACKGROUND: Cholera is a diarrheal disease that produces rapid dehydration. The infection is a significant cause of mortality and morbidity. Oral cholera vaccine (OCV) has been propagated for the prevention of cholera. Evidence on OCV delivery cost is insufficient in the African context. This study aims to analyze Shanchol vaccine delivery costs, focusing on the vaccination campaign in response of a cholera outbreak in Lake Chilwa, Malawi. METHODS: The vaccination campaign was implemented in two rounds in February and March 2016. Structured questionnaires were used to collect costs incurred for each vaccination related activity, including vaccine procurement and shipment, training, microplanning, sensitization, social mobilization and vaccination rounds. Costs collected, including financial and economic costs were analyzed using Choltool, a standardized cholera cost calculator. RESULTS: In total, 67,240 persons received two complete doses of the vaccine. Vaccine coverage was higher in the first round than in the second. The two-dose coverage measured with the immunization card was estimated at 58%. The total financial cost incurred in implementing the campaign was US$480275 while the economic cost was US$588637. The total financial and economic costs per fully vaccinated person were US$7.14 and US$8.75, respectively, with delivery costs amounting to US$1.94 and US$3.55, respectively. Vaccine procurement and shipment accounted respectively for 73% and 59% of total financial and economic costs of the total vaccination campaign costs while the incurred personnel cost accounted for 13% and 29% of total financial and economic costs. Cost for delivering a single dose of Shanchol was estimated at US$0.97. CONCLUSION: This study provides new evidence on economic and financial costs of a reactive campaign implemented by international partners in collaboration with MoH. It shows that involvement of international partners' personnel may represent a substantial share of campaign's costs, affecting unit and vaccine delivery costs.

The value of and challenges for cholera vaccines in Africa.

The 21st century saw a shift in the cholera burden from Asia to Africa. The risk factors for cholera outbreaks in Africa are incompletely understood, and the traditional emphasis on providing safe drinking water and improving sanitation and hygiene has proven remarkably insufficient to contain outbreaks. Current killed whole-cell oral cholera vaccines (OCVs) are safe and guarantee a high level of protection for several years. OCVs have been licensed for >20 years, but their potential for preventing and control cholera outbreaks in Africa has not been realized. Although each item in the long list of technical reasons why cholera vaccination campaigns have been deferred is plausible, we believe that the biggest barrier is that populations affected by cholera outbreaks are underprivileged and lack a strong political voice. The evaluation and use of OCVs as a tool for cholera control will require a new, more compassionate, less risk-averse generation of decision makers.

Cost of illness for cholera in a high risk urban area in Bangladesh: an analysis from household perspective.

BACKGROUND: Cholera poses a substantial health burden to developing countries such as Bangladesh. In this study, the objective is to estimate the economic burden of cholera treatments incurred by households. The study was carried out in the context of a large vaccine trial in an urban area of Bangladesh. METHODS: The study used a combination of prospective and retrospective incidence-based cost analyses of cholera illness per episode per household. A total of 394 confirmed cholera hospitalized cases were identified and treated in the study area during June-October 2011. Households with cholera patients were interviewed within 15 days after discharge from hospitals or clinics. To estimate the total cost of cholera illness a structured questionnaire was used, which included questions on direct medical costs, non-medical costs, and the indirect costs of patients and caregivers. RESULTS: The average total household cost of treatment for an episode of cholera was US$30.40. Total direct and indirect costs constituted 24.6% (US$7.40) and 75.4% (US$23.00) of the average total cost, respectively. The cost for children under 5 years of age (US$21.50) was higher than that of children aged 5-14 years (US$17.50). The direct cost of treatment was similar for male and female patients, but the indirect cost was higher for males. CONCLUSION: Our study suggests that by preventing one cholera episode (3 days on an average), we can avert a total cost of 2,278.50 BDT (US$30.40) per household. Among medical components, medicines are the largest cost driver. No clear socioeconomic gradient emerged from our study, but limited demographic patterns were observed in the cost of illness. By preventing cholera cases, large production losses can be reduced.

Socio-cultural determinants of anticipated acceptance of an oral cholera vaccine in Western Kenya.

Determinants of anticipated acceptance of an oral cholera vaccine (OCV) were studied in urban and rural communities of Western Kenya. An explanatory model interview administered to 379 community residents assessed anticipated vaccine acceptance at various prices from no cost to full-cost recovery, socio-cultural features of cholera and social characteristics. Nearly all (99%) residents indicated willingness to accept a no-cost OCV, 95% at a price of US$ 0·8, 73% at US$ 4·2 and 59% at US$ 8·4. Logistic regression models analysed socio-cultural determinants of anticipated OCV acceptance. Prominence of non-specific symptoms for cholera was negatively associated with acceptance. A cholera-specific symptom (thirst), self-help referring to prayer, income and education were positively associated. In the high-cost model, education was no longer significant and reliance on herbal treatment was a significant determinant of vaccine non-acceptance. Findings suggest high motivation for OCVs, if affordable. Socio-cultural determinants are better predictors of anticipated acceptance than socio-demographic factors alone.

Costs of illness due to endemic cholera.

Economic analyses of cholera immunization programmes require estimates of the costs of cholera. The Diseases of the Most Impoverished programme measured the public, provider, and patient costs of culture-confirmed cholera in four study sites with endemic cholera using a combination of hospital- and community-based studies. Families with culture-proven cases were surveyed at home 7 and 14 days after confirmation of illness. Public costs were measured at local health facilities using a micro-costing methodology. Hospital-based studies found that the costs of severe cholera were US$32 and US$47 in Matlab and Beira. Community-based studies in North Jakarta and Kolkata found that cholera cases cost between US$28 and US$206, depending on hospitalization. Patients' cost of illness as a percentage of average monthly income were 21% and 65% for hospitalized cases in Kolkata and North Jakarta, respectively. This burden on families is not captured by studies that adopt a provider perspective.

Effectiveness of a killed whole-cell oral cholera vaccine in Bangladesh: further follow-up of a cluster-randomised trial.

BACKGROUND: Killed whole-cell oral cholera vaccines (OCVs) are widely used for prevention of cholera in developing countries. However, few studies have evaluated the protection conferred by internationally recommended OCVs for durations beyond 2 years of follow-up. METHODS: In this study, we followed up the participants of a cluster-randomised controlled trial for 2 years after the end of the original trial. Originally, we had randomised 90 geographical clusters in Dhaka slums in Bangladesh in equal numbers (1:1:1) to a two-dose regimen of OCV alone (targeted to people aged 1 year or older), a two-dose regimen of OCV plus a water-sanitation-hygiene (WASH) intervention, or no intervention. There was no masking of group assignment. The WASH intervention conferred little additional protection to OCV and was discontinued at 2 years of follow-up. Surveillance for severe cholera was continued for 4 years. Because of the short duration and effect of the WASH intervention, we combined the two OCV intervention groups. The primary outcomes were OCV overall protection (protection of all members of the intervention clusters) and total protection (protection of individuals who got vaccinated in the intervention clusters) against severe cholera, which we assessed by multivariable survival models appropriate for cluster-randomised trials. This trial is registered on ClinicalTrials.gov, NCT01339845. FINDINGS: The study was done between April 17, 2011, and Nov 1, 2015. 268 896 participants were present at the time of the first dose, with 188 206 in the intervention group and 80 690 in the control group. OCV coverage of the two groups receiving OCV was 66% (123 659 of 187 214 participants). During 4 years of follow-up, 441 first episodes of severe cholera were detected (243 episodes in the vaccinated groups and as 198 episodes in the unvaccinated group). Overall OCV protection was 36% (95% CI 19 to 49%) and total OCV protection was 46% (95% CI 32 to 58). Cumulative total vaccine protection was notably lower for people vaccinated before the age of 5 years (24%; -30 to 56) than for people vaccinated at age 5 years or older (49%; 35 to 60), although the differences in protection for the two age groups were not significant (p=0·3308). Total vaccine protection dropped notably (p=0·0115) after 3 years in children vaccinated at 1-4 years of age. INTERPRETATION: These findings provide further evidence of long-term effectiveness of killed whole-cell OCV, and therefore further support for the use of killed whole-cell OCVs to control endemic cholera, but indicate that protection is shorter-lived in children vaccinated before the age of 5 years than in people vaccinated at the age of 5 years or older. FUNDING: Bill & Melinda Gates Foundation. TRANSLATION: For the Bengali translation of the abstract see Supplementary Materials section.

Economic burden of cholera in Asia.

BACKGROUND: The economic burden data can provide a basis to inform investments in cholera control and prevention activities. However, treatment costs and productivity loss due to cholera are not well studied. METHODS: We included Asian countries that either reported cholera cases to the World Health Organization (WHO) in 2015 or were considered cholera endemic in 2015 global burden of disease study. Public health service delivery costs for hospitalization and outpatient costs, out-of-pocket costs to patients and households, and lost productivity were extracted from literature. A probabilistic multivariate sensitivity analysis was conducted for key outputs using Monte Carlo simulation. Scenario analyses were conducted using data from the WHO cholera reports and conservative and liberal disease burden estimates. RESULTS: Our analysis included 14 Asian countries that were estimated to have a total of 850,000 cholera cases and 25,500 deaths in 2015 While, the WHO cholera report documented around 60,000 cholera cases and 28 deaths. We estimated around $20.2 million (I$74.4 million) in out-of-pocket expenditures, $8.5 million (I$30.1 million) in public sector costs, and $12.1 million (I$43.7 million) in lost productivity in 2015. Lost productivity due to premature deaths was estimated to be $985.7 million (I$3,638.6 million). Our scenario analyses excluding mortality costs showed that the economic burden ranged from 20.3% ($8.3 million) to 139.3% ($57.1 million) in high and low scenarios when compared to the base case scenario ($41 million) and was least at 10.1% ($4.1 million) when estimated based on cholera cases reported to WHO. CONCLUSION: The economic burden of cholera in Asia provides a better understanding of financial offsets that can be achieved, and the value of investments on cholera control measures. With a clear understanding of the limitations of the underlying assumptions, the information may be used in economic evaluations and policy decisions.

Costs and benefits of interventions aimed at major infectious disease threats: lessons from the literature.

Pandemics and major outbreaks have the potential to cause large health losses and major economic costs. To prioritize between preventive and responsive interventions, it is important to understand the costs and health losses interventions may prevent. We review the literature, investigating the type of studies performed, the costs and benefits included, and the methods employed against perceived major outbreak threats. We searched PubMed and SCOPUS for studies concerning the outbreaks of SARS in 2003, H5N1 in 2003, H1N1 in 2009, Cholera in Haiti in 2010, MERS-CoV in 2013, H7N9 in 2013, and Ebola in West-Africa in 2014. We screened titles and abstracts of papers, and subsequently examined remaining full-text papers. Data were extracted according to a pre-constructed protocol. We included 34 studies of which the majority evaluated interventions related to the H1N1 outbreak in a high-income setting. Most interventions concerned pharmaceuticals. Included costs and benefits, as well as the methods applied, varied substantially between studies. Most studies used a short time horizon and did not include future costs and benefits. We found substantial variation in the included elements and methods used. Policymakers need to be aware of this and the bias toward high-income countries and pharmaceutical interventions, which hampers generalizability. More standardization of included elements, methodology, and reporting would improve economic evaluations and their usefulness for policy.

Cost-effectiveness of new-generation oral cholera vaccines: a multisite analysis.

OBJECTIVES: We evaluated the cost-effectiveness of a low-cost cholera vaccine licensed and used in Vietnam, using recently collected data from four developing countries where cholera is endemic. Our analysis incorporated new findings on vaccine herd protective effects. METHODS: Using data from Matlab, Bangladesh, Kolkata, India, North Jakarta, Indonesia, and Beira, Mozambique, we calculated the net public cost per disability-adjusted life year avoided for three immunization strategies: 1) school-based vaccination of children 5 to 14 years of age; 2) school-based vaccination of school children plus use of the schools to vaccinate children aged 1 to 4 years; and 3) community-based vaccination of persons aged 1 year and older. RESULTS: We determined cost-effectiveness when vaccine herd protection was or was not considered, and compared this with commonly accepted cutoffs of gross domestic product (GDP) per person to classify interventions as cost-effective or very-cost effective. Without including herd protective effects, deployment of this vaccine would be cost-effective only in school-based programs in Kolkata and Beira. In contrast, after considering vaccine herd protection, all three programs were judged very cost-effective in Kolkata and Beira. Because these cost-effectiveness calculations include herd protection, the results are dependent on assumed vaccination coverage rates. CONCLUSIONS: Ignoring the indirect effects of cholera vaccination has led to underestimation of the cost-effectiveness of vaccination programs with oral cholera vaccines. Once these effects are included, use of the oral killed whole cell vaccine in programs to control endemic cholera meets the per capita GDP criterion in several developing country settings.

Effectiveness and economic analysis of the whole cell/recombinant B subunit (WC/rbs) inactivated oral cholera vaccine in the prevention of traveller's diarrhoea.

BACKGROUND: Nowadays there is a debate about the indication of the oral whole-cell/recombinant B-subunit cholera vaccine (WC/rBS) in traveller's diarrhoea. However, a cost-benefit analysis based on real data has not been published. METHODS: A cost-effectiveness and cost-benefit study of the oral cholera vaccine (WC/rBS), Dukoral for the prevention of traveller's diarrhoea (TD) was performed in subjects travelling to cholera risk areas. The effectiveness of WC/rBS vaccine in the prevention of TD was analyzed in 362 travellers attending two International Vaccination Centres in Spain between May and September 2005. RESULTS: The overall vaccine efficacy against TD was 42,6%. Direct healthcare-related costs as well as indirect costs (lost vacation days) subsequent to the disease were considered. Preventive vaccination against TD resulted in a mean saving of 79.26 euro per traveller. CONCLUSION: According to the cost-benefit analysis performed, the recommendation for WC/rBS vaccination in subjects travelling to zones at risk of TD is beneficial for the traveller, regardless of trip duration and visited continent.

A cholera transmission model incorporating the impact of medical resources.

We propose a mathematical model for the transmission dynamics of cholera under the impact of available medical resources. The model describes the interaction between the human hosts and the pathogenic bacteria and incorporates both the environment-to-human and human-to-human transmission routes. We conduct a rigorous equilibrium analysis to the model and establish the global asymptotic stability of the disease-free equilibrium when R0 ≤ 1 and that of the endemic equilibrium when R0 > 1. As a realistic case study, we apply our model to the Yemen cholera outbreak during 2017-2018. By fitting our simulation results to the epidemic data published by the World Health Organization, we find that different levels of disease prevalence and severity are linked to different geographical regions in this country and that cholera prevention and intervention efforts should be implemented strategically with respect to these regions in Yemen.

Modelling cholera transmission dynamics in the presence of limited resources.

OBJECTIVES: We study the transmission dynamics of cholera in the presence of limited resources, a common feature of the developing world. The model is used to gain insight into the impact of available resources of the health care system on the spread and control of the disease. A deterministic model that includes a nonlinear recovery rate is formulated and rigorously analyzed. Limited treatment is described by inclusion of a special treatment function. Center manifold theory is used to show that the model exhibits the phenomenon of backward bifurcation. Matlab has been used to carry out numerical simulations to support theoretical findings. RESULTS: The model analysis shows that the disease free steady state is locally stable when the threshold [Formula: see text]. It is also shown that the model has multiple equilibria and the model exhibits the phenomenon of backward bifurcation whose implications to cholera infection are discussed. The results are useful for the public health planning in resource allocation for the control of cholera transmission.

Evaluating the costs of cholera illness and cost-effectiveness of a single dose oral vaccination campaign in Lusaka, Zambia.

INTRODUCTION: In 2016, for the very first time, the Ministry of Health in Zambia implemented a reactive outbreak response to control the spread of cholera and vaccinated at-risk populations with a single dose of Shancol-an oral cholera vaccine (OCV). This study aimed to assess the costs of cholera illness and determine the cost-effectiveness of the 2016 vaccination campaign. METHODOLOGY: From April to June 2017, we conducted a retrospective cost and cost-effectiveness analysis in three peri-urban areas of Lusaka. To estimate costs of illness from a household perspective, a systematic random sample of 189 in-patients confirmed with V. cholera were identified from Cholera Treatment Centre registers and interviewed for out-of-pocket costs. Vaccine delivery and health systems costs were extracted from financial records at the District Health Office and health facilities. The cost of cholera treatment was derived by multiplying the subsidized cost of drugs by the quantity administered to patients during hospitalisation. The cost-effectiveness analysis measured incremental cost-effectiveness ratio-cost per case averted, cost per life saved and cost per DALY averted-for a single dose OCV. RESULTS: The mean cost per administered vaccine was US$1.72. Treatment costs per hospitalized episode were US$14.49-US$18.03 for patients ≤15 years old and US$17.66-US$35.16 for older patients. Whereas households incurred costs on non-medical items such as communication, beverages, food and transport during illness, a large proportion of medical costs were borne by the health system. Assuming vaccine effectiveness of 88.9% and 63%, a life expectancy of 62 years and Gross Domestic Product (GDP) per capita of US$1,500, the costs per case averted were estimated US$369-US$532. Costs per life year saved ranged from US$18,515-US$27,976. The total cost per DALY averted was estimated between US$698-US$1,006 for patients ≤15 years old and US$666-US$1,000 for older patients. CONCLUSION: Our study determined that reactive vaccination campaign with a single dose of Shancol for cholera control in densely populated areas of Lusaka was cost-effective.

Private demand for cholera vaccines in Hue, Vietnam.

OBJECTIVES: This study aims to measure the private demand for oral cholera vaccines in Hue, Vietnam, an area of relatively low endemicity of cholera, using the contingent valuation method. METHODS: Interviews were conducted with either the head of household or spouse in 800 randomly selected households with children less than 18 years old. Respondents were asked whether they would purchase an oral cholera vaccine with different levels of effectiveness and durations of effectiveness (both for themselves and for other household members) at a specified price. RESULTS: The median respondent willingness to pay for 50% effective/3-year vaccine was estimated to be approximately $5, although 17% of the study sample would not pay for a cholera vaccine. The median economic benefit to a household of vaccinating all household members against cholera, as measured by its stated willingness to pay, was estimated to be $40 for a vaccine with these attributes. CONCLUSIONS: The perceived private economic benefits of a cholera vaccine were high, but not evenly distributed across the population. A minority of the people in Hue place no value on receiving a cholera vaccine.

The health economics of cholera: A systematic review.

BACKGROUND: Vibrio cholera is a major contributor of diarrheal illness that causes significant morbidity and mortality globally. While there is literature on the health economics of diarrheal illnesses more generally, few studies have quantified the cost-of-illness and cost-effectiveness of cholera-specific prevention and control interventions. The present systematic review provides a comprehensive overview of the literature specific to cholera as it pertains to key health economic measures. METHODS: A systematic review was performed with no date restrictions up through February 2017 in PubMed, Econlit, Embase, Web of Science, and Cochrane Review to identify relevant health economics of cholera literature. After removing duplicates, a total of 1993 studies were screened and coded independently by two reviewers, resulting in 22 relevant studies. Data on population, methods, and results (cost-of-illness and cost-effectiveness of vaccination) were compared by country/region. All costs were adjusted to 2017 USD for comparability. RESULTS: Costs per cholera case were found to be rather low: <$100 per case in most settings, even when costs incurred by patients/families and lost productivity are considered. When wider socioeconomic costs are included, estimated costs are >$1000/case. There is adequate evidence to support the economic value of vaccination for the prevention and control of cholera when vaccination is targeted at high-incidence populations and/or areas with high case fatality rates due to cholera. When herd immunity is considered, vaccination also becomes a cost-effective option for the general population and is comparable in cost-effectiveness to other routine immunizations. CONCLUSIONS: Cholera vaccination is a viable short-to-medium term option, especially as the upfront costs of building water, sanitation, and hygiene (WASH) infrastructure are considerably higher for countries that face a significant burden of cholera. While WASH may be the more cost-effective solution in the long-term when implemented properly, cholera vaccination can still be a feasible, cost-effective strategy.

Global economic evaluation of oral cholera vaccine: A systematic review.

World Health Organization recommends oral cholera vaccine (OCV) to prevent and control cholera, but requires cost-effectiveness evidence. This review aimed to provide a critical appraisal and summary of global economic evaluation (EE) studies involving OCV to guide future EE study. Full EE studies, published from inception to December 2015, evaluating OCV against cholera disease were included. The included studies were appraised using WHO guide for standardization of EE of immunization programs. Out of 14 included studies, almost all (13/14) were in low- and middle-income countries. Most studies (11/14) evaluated mass vaccination program. Most of the studies (9/14) incorporated herd protective effect. The most common influential parameters were cholera incidence, OCV coverage, herd protection and OCV price. OCV vaccination is likely to be cost-effective when targeted at the population with high-risk of cholera and poor access to health care facilities when herd protection effect is incorporated and OCV price is low.

The impact and cost-effectiveness of controlling cholera through the use of oral cholera vaccines in urban Bangladesh: A disease modeling and economic analysis.

BACKGROUND: Cholera remains an important public health problem in major cities in Bangladesh, especially in slum areas. In response to growing interest among local policymakers to control this disease, this study estimated the impact and cost-effectiveness of preventive cholera vaccination over a ten-year period in a high-risk slum population in Dhaka to inform decisions about the use of oral cholera vaccines as a key tool in reducing cholera risk in such populations. METHODOLOGY/PRINCIPAL FINDINGS: Assuming use of a two-dose killed whole-cell oral cholera vaccine to be produced locally, the number of cholera cases and deaths averted was estimated for three target group options (1-4 year olds, 1-14 year olds, and all persons 1+), using cholera incidence data from Dhaka, estimates of vaccination coverage rates from the literature, and a dynamic model of cholera transmission based on data from Matlab, which incorporates herd effects. Local estimates of vaccination costs minus savings in treatment costs, were used to obtain incremental cost-effectiveness ratios for one- and ten-dose vial sizes. Vaccinating 1-14 year olds every three years, combined with annual routine vaccination of children, would be the most cost-effective strategy, reducing incidence in this population by 45% (assuming 10% annual migration), and costing was $823 (2015 USD) for single dose vials and $591 (2015 USD) for ten-dose vials per disability-adjusted life year (DALY) averted. Vaccinating all ages one year and above would reduce incidence by >90%, but would be 50% less cost-effective ($894-1,234/DALY averted). Limiting vaccination to 1-4 year olds would be the least cost-effective strategy (preventing only 7% of cases and costing $1,276-$1,731/DALY averted), due to the limited herd effects of vaccinating this small population and the lower vaccine efficacy in this age group. CONCLUSIONS/SIGNIFICANCE: Providing cholera vaccine to slum populations in Dhaka through periodic vaccination campaigns would significantly reduce cholera incidence and inequities, and be especially cost-effective if all 1-14 year olds are targeted.

[Consumption of medications during the cholera epidemic in Douala, Cameroon (2004)]. / Consommation de médicaments lors de l'épidémie de choléra de Douala (2004).

To prepare for cholera outbreaks, stockpiles of supplies, rehydration salts/ solutions and appropriate antibiotics must be placed in strategic locations to ensure a prompt and effective response. However specific needs have not been evaluated up to now. The purpose of this report is to give an accurate account of medical supplies that were consumed during the cholera epidemic in Douala in 2004. Consumption of medication for the entire epidemic was measured by crosschecking data from the provincial pharmaceutical supply centre with the order forms, stock sheets and records of hospitals. Cost was calculated based on pricing data from the National Supply Center. For the 5 020 confirmed cases of cholera that were treated in the 14 hospitals in Douala from January to September 2004, consumption consisted of 499,746 doxycycline tablets, 235,881 amoxicilline tablets, 122,781 rehydration salt packets, and 60,217 units of Ringer Lactate (500 ml). The total cost of medications and consumables was 52,229,311 CFAF (approximately 80,000 Euro). Although updated recommendations are not available, comparison with the existing ones shows that the consumption levels observed were 5 times higher for both rehydration and antibiotherapy. The mean cost of treatment in Douala was 13 Euro per reported patient. This cost rose to 15 Euro if antibiotic prophylaxis was prescribed for all contacts. These findings can be useful in planning for future epidemics by allowing recommendations to be updated. We propose the follow supply levels for 50,000 inhabitants with an attack rate of 0.2%: 10,000 doxycycline tablets, 5000 amoxicilline tablets (500 mg), 2500 SRO packs (for 2500 liters) and 600 liters of Ringer Lactate.