Sarah D. Bennett

Foodborne Disease Outbreaks caused by Bacillus cereus, Clostridium perfringens, and Staphylococcus aureus, United States, 1998–2008

From 1998 to 2008, 1229 foodborne outbreaks caused by Bacillus cereus, Clostridium perfringens, and Staphylococcus aureus were reported in the United States; 39% were reported with a confirmed etiology. Vomiting was commonly reported in B. cereus (median, 75% of cases) and S. aureus outbreaks (median, 87%), but rarely in C. perfringens outbreaks (median, 9%). Meat or poultry dishes were commonly implicated in C. perfringens (63%) and S. aureus (55%) outbreaks, and rice dishes were commonly implicated in B. cereus outbreaks (50%). Errors in food processing and preparation were commonly reported (93%), regardless of etiology; contamination by a food worker was only common in S. aureus outbreaks (55%). Public health interventions should focus on these commonly reported errors to reduce the occurrence of outbreaks caused by B. cereus, C. perfringens, and S. aureus in the United States.

Outbreak of Shiga Toxin-Producing Escherichia coli (STEC) O157:H7 Associated with Romaine Lettuce Consumption, 2011

Background Shiga toxin-producing Escherichia coli (STEC) O157:H7 is the causal agent for more than 96,000 cases of diarrheal illness and 3,200 infection-attributable hospitalizations annually in the United States. Materials and Methods We defined a confirmed case as a compatible illness in a person with the outbreak strain during 10/07/2011-11/30/2011. Investigation included hypothesis generation, a case-control study utilizing geographically-matched controls, and a case series investigation. Environmental inspections and tracebacks were conducted. Results We identified 58 cases in 10 states; 67% were hospitalized and 6.4% developed hemolytic uremic syndrome. Any romaine consumption was significantly associated with illness (matched Odds Ratio (mOR) = 10.0, 95% Confidence Interval (CI) = 2.1–97.0). Grocery Store Chain A salad bar was significantly associated with illness (mOR = 18.9, 95% CI = 4.5–176.8). Two separate traceback investigations for romaine lettuce converged on Farm A. Case series results indicate that cases (64.9%) were more likely than the FoodNet population (47%) to eat romaine lettuce (p-value = 0.013); 61.3% of cases reported consuming romaine lettuce from the Grocery Store Chain A salad bar. Conclusions This multistate outbreak of STEC O157:H7 infections was associated with consumption of romaine lettuce. Traceback analysis determined that a single common lot of romaine lettuce harvested from Farm A was used to supply Grocery Store Chain A and a university campus linked to a case with the outbreak strain. An investigation at Farm A did not identify the source of contamination. Improved ability to trace produce from the growing fields to the point of consumption will allow more timely prevention and control measures to be implemented.

Outbreaks Associated with Cantaloupe, Watermelon, and Honeydew in the United States, 1973–2011

Fresh fruits and vegetables are an important part of a healthy diet. Melons have been associated with enteric infections. We reviewed outbreaks reported to the Centers for Disease Control and Preventions Foodborne Disease Outbreak Surveillance System during 1973-2011 in which the implicated food was a single melon type. We also reviewed published literature and records obtained from investigating agencies. During 1973-2011, 34 outbreaks caused by a single melon type were reported, resulting in 3602 illnesses, 322 hospitalizations, 46 deaths, and 3 fetal losses. Cantaloupes accounted for 19 outbreaks (56%), followed by watermelons (13, 38%) and honeydew (2, 6%). Melon-associated outbreaks increased from 0.5 outbreaks per year during 1973-1991 to 1.3 during 1992-2011. Salmonella was the most common etiology reported (19, 56%), followed by norovirus (5, 15%). Among 13 outbreaks with information available, melons imported from Mexico and Central America were implicated in 9 outbreaks (69%) and domestically grown melons were implicated in 4 outbreaks (31%). The point of contamination was known for 20 outbreaks; contamination occurred most commonly during growth, harvesting, processing, or packaging (13, 65%). Preventive measures focused on reducing bacterial contamination of melons both domestically and internationally could decrease the number and severity of melon-associated outbreaks.

Ebola infection control in Sierra Leonean health clinics: A large cross-agency cooperative project

The Ebola virus disease outbreak occurring in West Africa has resulted in at least 199 cases of Ebola in Sierra Leonean health care workers, many as a result of transmission occurring in health facilities. The Ministry of Health and Sanitation of Sierra Leone recognized that improvements in infection prevention and control (IPC) were necessary at all levels of health care delivery. To this end, the U.S. Centers for Disease Control and Prevention, United Nations Childrens Fund, and multiple nongovernmental organizations implemented a national IPC training program in 1,200 peripheral health units (PHUs) in Sierra Leone. A tiered training of trainers program was used. Trainers conducted multiday trainings at PHUs and coordinated the delivery of personal protective equipment (gloves, gowns, masks, boots) and infection control supplies (chlorine, buckets, disposable rags, etc) to all PHU staff. Under the ongoing project, 4,264 health workers have already been trained, and 98% of PHUs have received their first shipment of supplies.

Acceptability and use of portable drinking water and hand washing stations in health care facilities and their impact on patient hygiene practices, Western kenya.

Many health care facilities (HCF) in developing countries lack access to reliable hand washing stations and safe drinking water. To address this problem, we installed portable, low-cost hand washing stations (HWS) and drinking water stations (DWS), and trained healthcare workers (HCW) on hand hygiene, safe drinking water, and patient education techniques at 200 rural HCFs lacking a reliable water supply in western Kenya. We performed a survey at baseline and a follow-up evaluation at 15 months to assess the impact of the intervention at a random sample of 40 HCFs and 391 households nearest to these HCFs. From baseline to follow-up, there was a statistically significant increase in the percentage of dispensaries with access to HWSs with soap (42% vs. 77%, p<0.01) and access to safe drinking water (6% vs. 55%, p<0.01). Female heads of household in the HCF catchment area exhibited statistically significant increases from baseline to follow-up in the ability to state target times for hand washing (10% vs. 35%, p<0.01), perform all four hand washing steps correctly (32% vs. 43%, p = 0.01), and report treatment of stored drinking water using any method (73% vs. 92%, p<0.01); the percentage of households with detectable free residual chlorine in stored drinking water did not change (6%, vs. 8%, p = 0.14). The installation of low-cost, low-maintenance, locally-available, portable hand washing and drinking water stations in rural HCFs without access to 24-hour piped water helped assure that health workers had a place to wash their hands and provide safe drinking water. This HCF intervention may have also contributed to the improvement of hand hygiene and reported safe drinking water behaviors among households nearest to HCFs.

Outbreak of Foodborne Botulism in an Immigrant Community: Overcoming Delayed Disease Recognition, Ambiguous Epidemiologic Links, and Cultural Barriers to Identify the Cause

We describe a botulism outbreak involving 4 Middle Eastern men complicated by delayed diagnosis, ambiguous epidemiologic links among patients, and illness onset dates inconsistent with a point-source exposure. Homemade turshi, a fermented vegetable dish, was the likely cause. Patients ate turshi at 2 locations on different days over 1 month.

Assessment of water, sanitation and hygiene interventions in response to an outbreak of typhoid fever in Neno District, Malawi

On May 2, 2009 an outbreak of typhoid fever began in rural villages along the Malawi-Mozambique border resulting in 748 illnesses and 44 deaths by September 2010. Despite numerous interventions, including distribution of WaterGuard (WG) for in-home water treatment and education on its use, cases of typhoid fever continued. To inform response activities during the ongoing Typhoid outbreak information on knowledge, attitudes, and practices surrounding typhoid fever, safe water, and hygiene were necessary to plan future outbreak interventions. In September 2010, a survey was administered to female heads in randomly selected households in 17 villages in Neno District, Malawi. Stored household drinking water was tested for free chlorine residual (FCR) levels using the N,N diethyl-p-phenylene diamine colorimetric method (HACH Company, Loveland, CO, USA). Attendance at community-wide educational meetings was reported by 56% of household respondents. Respondents reported that typhoid fever is caused by poor hygiene (77%), drinking unsafe water (49%), and consuming unsafe food (25%), and that treating drinking water can prevent it (68%). WaterGuard, a chlorination solution for drinking water treatment, was observed in 112 (56%) households, among which 34% reported treating drinking water. FCR levels were adequate (FCR ≥ 0.2 mg/L) in 29 (76%) of the 38 households who reported treatment of stored water and had stored water available for testing and an observed bottle of WaterGuard in the home. Soap was observed in 154 (77%) households, among which 51% reported using soap for hand washing. Educational interventions did not reach almost one-half of target households and knowledge remains low. Despite distribution and promotion of WaterGuard and soap during the outbreak response, usage was low. Future interventions should focus on improving water, sanitation and hygiene knowledge, practices, and infrastructure. Typhoid vaccination should be considered.

Considerations for use of Ebola vaccine during an emergency response

Vaccination against Ebola virus disease is a tool that may limit disease transmission and deaths in future outbreaks, integrated within traditional Ebola outbreak prevention and control measures. Although a licensed Ebolavirus vaccine (EV) is not yet available, the 2014-2016 West African Ebola outbreak has accelerated EV clinical trials and given public health authorities in Guinea, Liberia, and Sierra Leone experience with implementation of emergency ring vaccination. As evidence supporting the use of EV during an outbreak response has become available, public health authorities in at-risk countries are considering how to integrate EV into future emergency Ebola responses and for prevention in high-risk groups, such as healthcare workers and frontline workers (HCW/FLWs), even before an EV is licensed. This review provides an overview of Ebola epidemiology, immunology, and evidence to inform regional and country-level decisions regarding EV delivery during an emergency response and to at-risk populations before a licensed vaccine is available and beyond. Countries or regions planning to use EV will need to assess factors such as the likelihood of a future Ebolavirus outbreak, the most likely species to cause an outbreak, the availability of a safe and effective EV (unlicensed or licensed) for the affected population, capacity to implement Ebola vaccination in conjunction with standard Ebola outbreak control measures, and availability of minimum essential resources and regulatory requirements to implement emergency Ebola vaccination. Potential emergency vaccination strategies for consideration include ring or geographically targeted community vaccination, HCW/FLW vaccination, and mass vaccination. The development of guidelines and protocols for Ebola vaccination will help ensure that activities are standardized, evidence-based, and well-coordinated with overall Ebola outbreak response efforts in the future.