COVID-19 vaccination was launched in March 2021 in Uganda and initially prioritized persons >50 years of age, persons with underlying conditions, healthcare workers, teachers, and security forces. However, uptake remained low 5 months after the program launch. Makerere University's Infectious Diseases Institute supported Uganda's Ministry of Health in optimizing COVID-19 vaccination uptake models by using point-of-care, place of worship, and place of work engagement and the Social Assistance Grant for Empowerment model in 47 of 135 districts in Uganda, where we trained influencers to support mobilization for vaccination outreach under each model. During July-December, vaccination rates increased significantly in targeted regions, from 92% to 130% for healthcare workers, 40% to 90% for teachers, 25% to 33% for security personnel, 6% to 15% for persons >50 years of age, and 6% to 11% for persons with underlying conditions. Our approach could be adopted in other targeted vaccination campaigns for future pandemics.

BACKGROUND: On 20 September 2022, Uganda declared its fifth Sudan virus disease (SVD) outbreak, culminating in 142 confirmed and 22 probable cases. The reproductive rate (R) of this outbreak was 1.25. We described persons who were exposed to the virus, became infected, and they led to the infection of an unusually high number of cases during the outbreak. METHODS: In this descriptive cross-sectional study, we defined a super-spreader person (SSP) as any person with real-time polymerase chain reaction (RT-PCR) confirmed SVD linked to the infection of ≥ 13 other persons (10-fold the outbreak R). We reviewed illness narratives for SSPs collected through interviews. Whole-genome sequencing was used to support epidemiologic linkages between cases. RESULTS: Two SSPs (Patient A, a 33-year-old male, and Patient B, a 26-year-old male) were identified, and linked to the infection of one probable and 50 confirmed secondary cases. Both SSPs lived in the same parish and were likely infected by a single ill healthcare worker in early October while receiving healthcare. Both sought treatment at multiple health facilities, but neither was ever isolated at an Ebola Treatment Unit (ETU). In total, 18 secondary cases (17 confirmed, one probable), including three deaths (17%), were linked to Patient A; 33 secondary cases (all confirmed), including 14 (42%) deaths, were linked to Patient B. Secondary cases linked to Patient A included family members, neighbours, and contacts at health facilities, including healthcare workers. Those linked to Patient B included healthcare workers, friends, and family members who interacted with him throughout his illness, prayed over him while he was nearing death, or exhumed his body. Intensive community engagement and awareness-building were initiated based on narratives collected about patients A and B; 49 (96%) of the secondary cases were isolated in an ETU, a median of three days after onset. Only nine tertiary cases were linked to the 51 secondary cases. Sequencing suggested plausible direct transmission from the SSPs to 37 of 39 secondary cases with sequence data. CONCLUSION: Extended time in the community while ill, social interactions, cross-district travel for treatment, and religious practices contributed to SVD super-spreading. Intensive community engagement and awareness may have reduced the number of tertiary infections. Intensive follow-up of contacts of case-patients may help reduce the impact of super-spreading events.

Uganda used Ebola vaccines as part of its preparedness and response during the 2018-2020 10th Ebola virus disease (EVD) outbreak in neighboring Democratic Republic of the Congo (DRC). We evaluated the public's perceptions of Ebola vaccines and compared their confidence in health services to treat Ebola versus malaria and tuberculosis as part of a survey on Ebola knowledge, attitudes, and practices (KAP) conducted in March 2020. A cross-sectional household survey was implemented in six districts in Uganda using multi-stage cluster sampling to randomly select participants. The districts were purposively selected from districts classified by the government as at high- or low-risk for an EVD outbreak. We describe perceptions of Ebola vaccines and confidence in health services to treat Ebola, tuberculosis, and malaria. Modified Poisson regression modeling was used to identify the demographic correlates of these outcomes. Among 3,485 respondents, 18% were aware of Ebola vaccines. Of those, 92% agreed that the vaccines were needed to prevent Ebola. Participants aged 15-24 years were 4% more likely to perceive such need compared to those 60 years and older (adjusted prevalence ratio [aPR] 1.04, 95% confidence interval [CI] 1.0-1.08). The perceived need was 5% lower among participants with at least some secondary education compared to uneducated participants (aPR 0.95; 0.92-0.99). Overall, 81% of those aware of the vaccines believed that everyone or most people in their community would get vaccinated if offered, and 94% said they would likely get vaccinated if offered. Confidence in health services to treat Ebola was lower compared to treating malaria or tuberculosis (55% versus 93% and 77%, respectively). However, participants from the EVD high-risk districts were 22% more likely to be confident in health services to treat Ebola compared to those in low-risk districts (aPR: 1.22; 95% CI: 1.08, 1.38). Our findings suggest that intent to take an Ebola vaccine during an outbreak was strong, but more work needs to be done to increase public awareness of these vaccines. The public's high confidence in health services to treat other health threats, such as malaria and tuberculosis, offer building blocks for strengthening their confidence in health services to treat EVD in the event of an outbreak.

In response to the COVID-19 pandemic, we established and sustained local production of Alcohol-Based Hand Rub (ABHR) at a district scale for healthcare facilities and community, public locations in four districts in Uganda. District officials provided space and staff for production units. The project renovated space for production, trained staff on ABHR production, and transported ABHR to key locations. The production officer conducted internal ABHR quality assessments while trained district health inspectors conducted external quality assessments prior to distribution. Information, education, and communication materials accompanied ABHR distribution. Onsite ABHR consumption was moni-tored by site staff using stock cards. On average, it took 11 days (range: 8–14) and 5,760 USD (range: 4,400–7,710) to setup a production unit. From March to December 2021, 21,600 L of quality-controlled ABHR were produced for 111 healthcare facilities and community locations at an average cost of 4.30 USD/L (range: 3.50–5.76). All ABHR passed both internal and external quality control (average ethanol concentration of 80%, range: 78–81%). This case study demonstrated that establishing centralized, local production of quality-controlled, affordable ABHR at a district-wide scale is feasible and strengthens the ability of healthcare workers and community locations to access and use ABHR during infectious disease outbreaks in low-resource countries. © 2023 The Authors.

Uganda has implemented several interventions that have contributed to prevention, early detection, and effective response to Public Health Emergencies (PHEs). However, there are gaps in collecting and documenting data on the overall response to these PHEs. We set out to establish a comprehensive electronic database of PHEs that occurred in Uganda since 2000. We constituted a core development team, developed a data dictionary, and worked with Health Information Systems Program (HISP)-Uganda to develop and customize a compendium of PHEs using the electronic Integrated Disease Surveillance and Response (eIDSR) module on the District Health Information Software version 2 (DHIS2) platform. We reviewed literature for retrospective data on PHEs for the compendium. Working with the Uganda Public Health Emergency Operations Center (PHEOC), we prospectively updated the compendium with real-time data on reported PHEs. We developed a user's guide to support future data entry teams. An operational compendium was developed within the eIDSR module of the DHIS2 platform. The variables for PHEs data collection include those that identify the type, location, nature and time to response of each PHE. The compendium has been updated with retrospective PHE data and real-time prospective data collection is ongoing. Data within this compendium is being used to generate information that can guide future outbreak response and management. The compendium development highlights the importance of documenting outbreak detection and response data in a central location for future reference. This data provides an opportunity to evaluate and inform improvements in PHEs response.

Uganda established a National Action Plan for Health Security in 2019, following a Joint External Evaluation (JEE) of International Health Regulations (2005) capacities in 2017. The action plan enhanced national health security awareness, but implementation efforts were affected by limited funding, excess of activities, and challenges related to monitoring and evaluation. To improve implementation, Uganda conducted a multisectoral health security self-assessment in 2021 using the second edition of the JEE tool and developed a 1-year operational plan. From 2017 to 2021, Uganda's composite ReadyScore improved by 20%, with improvement in 13 of the 19 technical areas. Indicator scores showing limited capacity declined from 30% to 20%, and indicators with no capacity declined from 10% to 2%. More indicators had developed (47% vs 40%), demonstrated (29% vs 20%), and sustained (2% vs 0%) capacities in 2021 compared with 2017. Using the self-assessment JEE scores, 72 specific activities from the International Health Regulations (2005) benchmarks tool were selected for inclusion in a 1-year operational plan (2021-2022). In contrast to the 264 broad activities in the 5-year national action plan, the operational plan prioritized a small number of activities to enable sectors to focus limited resources on implementation. While certain capacities improved before and during implementation of the action plan, countries may benefit from using short-term operational planning to develop realistic and actionable health security plans to improve health security capacities.

BACKGROUND: The global need for well-trained field epidemiologists has been underscored in the last decade in multiple pandemics, the most recent being COVID-19. Field Epidemiology Training Programs (FETPs) are in-service training programs that improve country capacities to respond to public health emergencies across different levels of the health system. Best practices for FETP implementation have been described previously. The Uganda Public Health Fellowship Program (PHFP), or Advanced-FETP in Uganda, is a two-year fellowship in field epidemiology funded by the U.S. Centers for Disease Control and situated in the Uganda National Institute of Public Health (UNIPH). We describe how specific attributes of the Uganda PHFP that are aligned with best practices enabled substantial contributions to the COVID-19 response in Uganda. METHODS: We describe the PHFP in Uganda and review examples of how specific program characteristics facilitate integration with Ministry of Health needs and foster a strong response, using COVID-19 pandemic response activities as examples. We describe PHFP activities and outputs before and during the COVID-19 response and offer expert opinions about the impact of the program set-up on these outputs. RESULTS: Unlike nearly all other Advanced FETPs in Africa, PHFP is delinked from an academic degree-granting program and enrolls only post-Master's-degree fellows. This enables full-time, uninterrupted commitment of academically-trained fellows to public health response. Uganda's PHFP has strong partner support in country, sufficient technical support from program staff, Ministry of Health (MoH), CDC, and partners, and full-time dedicated directorship from a well-respected MoH staff member. The PHFP is physically co-located inside the UNIPH with the emergency operations center (EOC), which provides a direct path for health alerts to be investigated by fellows. It has recognized value within the MoH, which integrates graduates into key MoH and partner positions. During February 2020-September 2021, PHFP fellows and graduates completed 67 major COVID-related projects. PHFP activities during the COVID-19 response were specifically requested by the MoH or by partners, or generated de novo by the program, and were supervised by all partners. CONCLUSION: Specific attributes of the PHFP enable effective service to the Ministry of Health in Uganda. Among the most important is the enrollment of post-graduate fellows, which leads to a high level of utilization of the program fellows by the Ministry of Health to fulfill real-time needs. Strong leadership and sufficient technical support permitted meaningful program outputs during COVID-19 pandemic response. Ensuring the inclusion of similar characteristics when implementing FETPs elsewhere may allow them to achieve a high level of impact.

Continuity of key water, sanitation, and hygiene (WASH) infrastructure and WASH practices-for example, hand hygiene-are among several critical community preventive and mitigation measures to reduce transmission of infectious diseases, including COVID-19 and other respiratory diseases. WASH guidance for COVID-19 prevention may combine existing WASH standards and new COVID-19 guidance. Many existing WASH tools can also be modified for targeted WASH assessments during the COVID-19 pandemic. We partnered with local organizations to develop and deploy tools to assess WASH conditions and practices and subsequently implement, monitor, and evaluate WASH interventions to mitigate COVID-19 in low- and middle-income countries in Latin America and the Caribbean and Africa, focusing on healthcare, community institution, and household settings and hand hygiene specifically. Employing mixed-methods assessments, we observed gaps in access to hand hygiene materials specifically despite most of those settings having access to improved, often onsite, water supplies. Across countries, adherence to hand hygiene among healthcare providers was about twice as high after patient contact compared to before patient contact. Poor or non-existent management of handwashing stations and alcohol-based hand rub (ABHR) was common, especially in community institutions. Markets and points of entry (internal or external border crossings) represent congregation spaces, critical for COVID-19 mitigation, where globally-recognized WASH standards are needed. Development, evaluation, deployment, and refinement of new and existing standards can help ensure WASH aspects of community mitigation efforts that remain accessible and functional to enable inclusive preventive behaviors.

Ebola virus disease (EVD) is a rare and often deadly viral hemorrhagic fever (VHF); four species of Ebola virus (Zaire ebolavirus, Sudan ebolavirus, Taï Forest ebolavirus, and Bundibugyo ebolavirus) cause occasional outbreaks among humans and nonhuman primates* (1). Infection is transmitted through direct contact with infectious blood, body fluids, and animal tissues. Symptoms include fever, abdominal pain, diarrhea, vomiting, generalized body weakness, and hemorrhage. Since 2000, four outbreaks of EVD caused by Sudan ebolavirus have been identified in Uganda; the largest outbreak (in 2000) resulted in 425 cases and 224 (53%) deaths (2,3). No vaccine is available to prevent Sudan ebolavirus infection, and treatment is supportive. The estimated case fatality rate is 55% (4).

Uganda is an ecological hot spot with porous borders that lies in several infectious disease transmission belts, making it prone to disease outbreaks. To prepare and respond to these public health threats and emergencies in a coordinated manner, Uganda established the Uganda National Institute of Public Health (UNIPH) in 2013.Using a step-by-step process, Uganda's Ministry of Health (MOH) crafted a strategy with a vision, mission, goal, and strategic objectives, and identified value additions and key enablers for success. A regulatory impact assessment was then conducted to inform the drafting of principles of the bill for legislation on the Institute.Despite not yet attaining legal status, the UNIPH has already achieved faster, smarter, and more efficient and effective prevention, detection, and response to public health emergencies. Successes include a more coordinated multisectoral, disciplined, and organized response to emergencies; appropriate, timely, and complete information receipt and sharing; a functional national lab sample and results transportation network that has enabled detection and confirmation of public health events within 48 hours of alert; appropriate response to a confirmed public health event in 24-48 hours; and real-time surveillance of endemic- and epidemic-prone diseases.In this article, we document success stories, lessons learned, and challenges encountered during the unique staged process used to develop the components of the UNIPH. The creation of an integrated disease control center has proven to yield better collaboration and synergies between different arms of epidemic preparedness and response.

Uganda is highly vulnerable to public health emergencies (PHEs) due to its geographic location next to the Congo Basin epidemic hot spot, placement within multiple epidemic belts, high population growth rates, and refugee influx. In view of this, Uganda's Ministry of Health established the Public Health Emergency Operations Center (PHEOC) in September 2013, as a central coordination unit for all PHEs in the country. Uganda followed the World Health Organization's framework to establish the PHEOC, including establishing a steering committee, acquiring legal authority, developing emergency response plans, and developing a concept of operations. The same framework governs the PHEOC's daily activities. Between January 2014 and December 2021, Uganda's PHEOC coordinated response to 271 PHEs, hosted 207 emergency coordination meetings, trained all core staff in public health emergency management principles, participated in 21 simulation exercises, coordinated Uganda's Global Health Security Agenda activities, established 6 subnational PHEOCs, and strengthened the capacity of 7 countries in public health emergency management. In this article, we discuss the following lessons learned: PHEOCs are key in PHE coordination and thus mitigate the associated adverse impacts; although the functions of a PHEOC may be legalized by the existence of a National Institute of Public Health, their establishment may precede formally securing the legal framework; staff may learn public health emergency management principles on the job; involvement of leaders and health partners is crucial to the success of a public health emergency management program; subnational PHEOCs are resourceful in mounting regional responses to PHEs; and service on the PHE Strategic Committee may be voluntary.

Introduction: During the 2018–2020 Ebola virus disease (EVD) outbreak in the Democratic Republic of the Congo, risk communication and community engagement (RCCE) were prioritized in geographic areas in Uganda considered at high risk of introduction of EVD. To inform EVD preparedness in Uganda, we evaluated community perceptions and prevention practices related to EVD in 6 districts in Uganda. Methods: In March 2020, we conducted a population-based survey in 6 purposively selected districts in Uganda using multistage cluster sampling. We examined differences between districts classified as high- versus low risk for EVD in terms of their message exposure from RCCE; risk perception; and EVD knowledge, attitudes, and prevention practices. Results: A total of 3,485 respondents were interviewed (91% response rate). EVD message exposure was more common in the high- versus low-risk districts. EVD risk perceptions were low overall but greater in the high- versus low-risk districts. Comprehensive knowledge was significantly greater in the high- versus low-risk districts (adjusted prevalence ratio [aPR] 1.61, 95% confidence interval [CI]=1.35, 1.93). Respondents’ engagement in all 3 EVD prevention practices (frequent handwashing with soap, avoiding physical contact with suspected Ebola patients, and avoiding burials involving contact with a corpse) was very low (4%). However, respondents with comprehensive knowledge were more likely to engage in all 3 EVD prevention practices compared to respondents without comprehensive knowledge (aPR 1.87, 95% CI=1.08, 3.25). Conclusion: Our findings suggest that while RCCE efforts as part of EVD outbreak preparedness may have contributed to higher EVD knowledge in the targeted high-risk districts, uptake of prevention behaviors was similarly low across districts. In a non-outbreak setting, implementing targeted RCCE strategies may not be sufficient to motivate people to adopt protective behaviors in the absence of a high threshold of perceived threat such as in an active outbreak. © Musaazi et al.

The SARS-CoV-2 Delta variant emerged shortly after COVID-19 vaccines became available in 2021. We describe SARS-CoV-2 breakthrough infections in a highly vaccinated, well-monitored US Embassy community in Kampala, Uganda. Defining breakthrough infection rates in highly vaccinated populations can help determine public health messaging, guidance, and policy globally.

BACKGROUND: On March 13, 2020, Uganda instituted COVID-19 symptom screening at its international airport, isolation and SARS-CoV-2 testing for symptomatic persons, and mandatory 14-day quarantine and testing of persons traveling through or from high-risk countries. On March 21, 2020, Uganda reported its first SARS-CoV-2 infection in a symptomatic traveler from Dubai. By April 12, 2020, 54 cases and 1257 contacts were identified. We describe the epidemiological, clinical, and transmission characteristics of these cases. METHODS: A confirmed case was laboratory-confirmed SARS-CoV-2 infection during March 21-April 12, 2020 in a resident of or traveler to Uganda. We reviewed case-person files and interviewed case-persons at isolation centers. We identified infected contacts from contact tracing records. RESULTS: Mean case-person age was 35 (±16) years; 34 (63%) were male. Forty-five (83%) had recently traveled internationally ('imported cases'), five (9.3%) were known contacts of travelers, and four (7.4%) were community cases. Of the 45 imported cases, only one (2.2%) was symptomatic at entry. Among all case-persons, 29 (54%) were symptomatic at testing and five (9.3%) were pre-symptomatic. Among the 34 (63%) case-persons who were ever symptomatic, all had mild disease: 16 (47%) had fever, 13 (38%) reported headache, and 10 (29%) reported cough. Fifteen (28%) case-persons had underlying conditions, including three persons with HIV. An average of 31 contacts (range, 4-130) were identified per case-person. Five (10%) case-persons, all symptomatic, infected one contact each. CONCLUSION: The first 54 case-persons with SARS-CoV-2 infection in Uganda primarily comprised incoming air travelers with asymptomatic or mild disease. Disease would likely not have been detected in these persons without the targeted testing interventions implemented in Uganda. Transmission was low among symptomatic persons and nonexistent from asymptomatic persons. Routine, systematic screening of travelers and at-risk persons, and thorough contact tracing will be needed for Uganda to maintain epidemic control.

More than ever, competent field epidemiologists are needed worldwide. As known, new, and resurgent communicable diseases increase their global impact, the International Health Regulations and the Global Health Security Agenda call for sufficient field epidemiologic capacity in every country to rapidly detect, respond to, and contain public health emergencies, thereby ensuring global health security. To build this capacity, for >35 years the US Centers for Disease Control and Prevention has worked with countries around the globe to develop Field Epidemiology Training Programs (FETPs). FETP trainees conduct surveillance activities and outbreak investigations in service to ministry of health programs to prevent and control infectious diseases of global health importance such as polio, cholera, tuberculosis, HIV/AIDS, malaria, and emerging zoonotic infectious diseases. FETP graduates often rise to positions of leadership to direct such programs. By training competent epidemiologists to manage public health events locally and support public health systems nationally, health security is enhanced globally.

INTRODUCTION: This study describes the development of a self-audit tool for public health and the associated methodology for implementing a district health system self-audit tool that can provide quantitative data on how district governments perceive their performance of the essential public health functions. METHODS: Development began with a consensus-building process to engage Ministry of Health and provincial health officers in Mozambique and Botswana. We then worked with lists of relevant public health functions as determined by these stakeholders to adapt a self-audit tool describing essential public health functions to each country's health system. We then piloted the tool across districts in both countries and conducted interviews with district health personnel to determine health workers' perception of the usefulness of the approach. RESULTS: Country stakeholders were able to develop consensus around 11 essential public health functions that were relevant in each country. Pilots of the self-audit tool enabled the tool to be effectively shortened. Pilots also disclosed a tendency to upcode during self-audits that was checked by group deliberation. Convening sessions at the district enabled better attendance and representative deliberation. Instant feedback from the audit was a feature that 100% of pilot respondents found most useful. CONCLUSION: The development of metrics that provide feedback on public health performance can be used as an aid in the self-assessment of health system performance at the district level. Measurements of practice can open the door to future applications for practice improvement and research into the determinants and consequences of better public health practice. The current tool can be assessed for its usefulness to district health managers in improving their public health practice. The tool can also be used by the Ministry of Health or external donors in the African region for monitoring the district-level performance of the essential public health functions.

Realizing the fundamental contribution of human resources to public health, the World Health Organization (WHO) issued policy recommendations for health worker retention. We reviewed Mozambique's laws and regulations and assessed the extent to which this legal and regulatory framework governing public sector health workers aligns with the WHO health worker retention recommendations. We provide guidance for future analysis of non-binding policies that may fill gaps identified in our review. We also indicate how to link legal analysis to the cycle by which research informs policy, policy informs practice, and practice leads to improvements in health systems and population health. Finally, we demonstrate the relevance of understanding and analyzing the impact of domestic laws on global health. Future research should assess implementation of health worker allowances and any associations with increased hiring, more equitable distribution, and improved retention - all are essential to public health in Mozambique.

BACKGROUND: Despite control efforts, salmonellosis continues to cause an estimated 1.2 million infections in the United States (US) annually. We describe the incidence of salmonellosis in the US and introduce a novel approach to examine the epidemiologic similarities and differences of individual serotypes. METHODS: Cases of salmonellosis in humans reported to the laboratory-based National Salmonella Surveillance System during 1996-2011 from US states were included. Coefficients of variation were used to describe distribution of incidence rates of common Salmonella serotypes by geographic region, age group and sex of patient, and month of sample isolation. RESULTS: During 1996-2011, more than 600,000 Salmonella isolates from humans were reported, with an average annual incidence of 13.1 cases/100,000 persons. The annual reported rate of Salmonella infections did not decrease during the study period. The top five most commonly reported serotypes, Typhimurium, Enteritidis, Newport, Heidelberg, and Javiana, accounted for 62% of fully serotyped isolates. Coefficients of variation showed the most geographically concentrated serotypes were often clustered in Gulf Coast states and were also more frequently found to be increasing in incidence. Serotypes clustered in particular months, age groups, and sex were also identified and described. CONCLUSIONS: Although overall incidence rates of Salmonella did not change over time, trends and epidemiological factors differed remarkably by serotype. A better understanding of Salmonella, facilitated by this comprehensive description of overall trends and unique characteristics of individual serotypes, will assist in responding to this disease and in planning and implementing prevention activities.

SUMMARY: In 2008, nationwide investigations of a Salmonella serotype Saintpaul outbreak led first to consumer warnings for Roma and red round tomatoes, then later for jalapeno and serrano peppers. In New Mexico, where there were a large number of cases but no restaurant-based clusters, the NM Department of Health and the Indian Health Service participated with CDC in individual-level and household-level case-control studies of infections in New Mexico and the Navajo Nation. No food item was associated in the individual-level study. In the household-level study, households with an ill member were more likely to have had jalapeno peppers present during the exposure period and to have reported ever having serrano peppers in the household. This report illustrates the complexity of this investigation, the limitations of traditional individual-level case-control studies when vehicles of infection are ingredients or commonly eaten with other foods, and the added value of a household-level study.

BACKGROUND: Raw produce is an increasingly recognized vehicle for salmonellosis. We investigated a nationwide outbreak that occurred in the United States in 2008. METHODS: We defined a case as diarrhea in a person with laboratory-confirmed infection with the outbreak strain of Salmonella enterica serotype Saintpaul. Epidemiologic, traceback, and environmental studies were conducted. RESULTS: Among the 1500 case subjects, 21% were hospitalized, and 2 died. In three case-control studies of cases not linked to restaurant clusters, illness was significantly associated with eating raw tomatoes (matched odds ratio, 5.6; 95% confidence interval [CI], 1.6 to 30.3); eating at a Mexican-style restaurant (matched odds ratio, 4.6; 95% CI, 2.1 to infinity) and eating pico de gallo salsa (matched odds ratio, 4.0; 95% CI, 1.5 to 17.8), corn tortillas (matched odds ratio, 2.3; 95% CI, 1.2 to 5.0), or salsa (matched odds ratio, 2.1; 95% CI, 1.1 to 3.9); and having a raw jalapeno pepper in the household (matched odds ratio, 2.9; 95% CI, 1.2 to 7.6). In nine analyses of clusters associated with restaurants or events, jalapeno peppers were implicated in all three clusters with implicated ingredients, and jalapeno or serrano peppers were an ingredient in an implicated item in the other three clusters. Raw tomatoes were an ingredient in an implicated item in three clusters. The outbreak strain was identified in jalapeno peppers collected in Texas and in agricultural water and serrano peppers on a Mexican farm. Tomato tracebacks did not converge on a source. CONCLUSIONS: Although an epidemiologic association with raw tomatoes was identified early in this investigation, subsequent epidemiologic and microbiologic evidence implicated jalapeno and serrano peppers. This outbreak highlights the importance of preventing raw-produce contamination.