Going public: Epidemiology works, especially when so many are sick with E. coli O157

With two dead and at least 151 sick with E. coli O157, believed to be from imported rocket (like bagged lettuce), Public Health England (PHE) says the products are still on supermarket shelves because the source of the outbreak had not been confirmed.

lettuce.skull.e.coli.O145Instead, officials are reiterating advice to wash vegetables, including salad leaves, thoroughly before eating them.

Washing is not going to remove much E. coli O157.

Stephen Adams of the Daily Mail writes that children are among those ill.

PHE would not say if the more than 60 patients needing hospital treatment were children or among the fatalities.

Several food wholesalers have been told to ‘stop adding some imported rocket leaves to their mixed salad products while investigations are ongoing,’ said the Food Standards Agency.

Epi works: Over 300 sickened from crypto on pre-cut salad greens in UK, 2012

In May 2012, people in England and Scotland started getting sick with Cryptosporidium. In June, 2012, the UK Health Protection Agency first announced 267 people were sick with Cryptosporidium across four areas of the UK, double the normal rate.

lettuce.harvestTen months later, HPA said the crypto that sickened about 300 people was most likely linked to eating pre-cut bagged salad products which were likely to have been labeled as ‘ready-to-eat.’

The outbreak was short lived and the numbers of cases returned to expected seasonal levels within a month of the first cases being reported. Most of those affected had a mild to moderate form of illness and there were no deaths associated with the outbreak.

During the investigation, an initial link was found between illness and pre-cut spinach. When specific retailers were included in the analysis, the strongest association with infection was found to be with consumption of ready to eat pre-cut mixed salad leaves from a major supermarket chain.

In this analysis, exposure to pre-cut spinach only reached conventional levels of significance for one retailer – a second major supermarket chain. A link to spinach from a number of other retailers was also suggested but these were not statistically significant. Together these findings suggest that one or more types of salad vegetables could have been contaminated.

Dr Stephen Morton, regional director of the HPA’s Yorkshire and the Humber region and head of the multi-agency Outbreak Control Team, said, “Our findings suggest that eating mixed leaf bagged salad was the most likely cause of illness. It is however often difficult to identify the source of short lived outbreaks of this type as by the time that the outbreak can be investigated, the affected food and much of the microbiological evidence may no longer be available

Dr Alison Gleadle, director of food safety at the FSA, took the opportunity to further confuse consumers, stating, “We’d like to remind everyone of our usual advice to wash all fruits and vegetables, including salad, before you eat them, unless they are labeled ready-to-eat.”

lettuce.skull.e.coli.O145But wasn’t this outbreak linked to ready-to-eat salads? How is that advice of any use? Could have offered some details, like, additional washing of ready-to-eat products is largely ineffective. FSA is refocusing its efforts on farm management to limit such contamination, before it happens.

A spokesthingy from retailer Morrisons said, rather defensively, “Morrisons is not the source of this outbreak. We have received no complaints of illness and no Morrisons products have tested positive for Cryptosporidia.

“The HPA’s claim is based solely on statistics, not testing. The very same statistics also implicated products from other retailers that the HPA recognize as ‘implausible’.”

Why doesn’t Morrison’s say what they do to enhance the safety of products they sell rather than trash epidemiology?

In the scientific paper on the outbreak, McKerr et. al reported a widespread foodborne outbreak of Cryptosporidium parvum in England and Scotland in May 2012. Cases were more common in female adults, and had no history of foreign travel. Over 300 excess cases were identified during the period of the outbreak. Speciation and microbiological typing revealed the outbreak strain to be C. parvum gp60 subtype IIaA15G2R1.

METHODS: Hypothesis generation questionnaires were administered and an unmatched case control study was undertaken to test the hypotheses raised. Cases and controls were interviewed by telephone. Controls were selected using sequential digit dialling. Information was gathered on demographics, foods consumed and retailers where foods were purchased.

RESULTS: Seventy-four laboratory confirmed cases and 74 controls were included in analyses. Infection was found to be strongly associated with the consumption of pre-cut mixed salad leaves sold by a single retailer. This is the largest documented outbreak of cryptosporidiosis attributed to a food vehicle.

An outbreak of cryptosporidium parvum across England & Scotland associated with consumption of fresh pre-cut salad leaves, May 2012


McKerr C1, Adak GK2, Nichols G3, Gorton R4, Chalmers RM5, Kafatos

PLoS One, 2015, doi: 10.1371/journal.pone.0125955. eCollection 2015.


Bangladesh health officials use traditional media to look for illness clusters

New York City and Chicago have been using social media as a supplemental tool to identify illness clusters and connect with potential victims.

Developing countries, where laboratory-based surveillance infrastructure is low, may use traditional media as an outbreak indicator. The cost is relatively low and it can provide a starting point.

Like in Bangladesh. A study published in EID details how traditional media clips have helped their surveillance activities.

The national rapid response team, consisting of key staff members from IEDCR, received a daily email containing all identified health-related newspaper articles and video clips. The team examined each news item and decided whether it warranted an outbreak response on the basis of expert clinical and epidemiologic knowledge; public health importance (e.g., number of cases and deaths reported, severity of symptoms); and verification by local health officials. For the purposes of this analysis, IEDCR retrospectively created a database of reported events sent by the media scanning company, which included the number of reported events, outbreak etiology, news source, and the outcome of each investigation. The outbreaks reported were classified by media type, etiology, and season.

Key informant interviews consistently indicated that the system was simple, flexible, timely, and acceptable because it used existing media infrastructure and required only minimal costs to contract with a company to compile daily reports of news items. Changes to the system could be implemented effectively through frequent communications between the media scanning company and IEDCR. The system was widely acceptable by all stakeholders and was considered a valuable component of disease surveillance in Bangladesh.

I miss Bill Keene: Museum catalogues food poisoning in Oregon, elsewhere

Lynne Terry of The Oregonian writes that an unusual museum stocked with food packages including everything from ground beef to alfalfa sprouts has gone live on the internet.

The Outbreak Museum, physically located in Portland, showcases the culprits in food poisoning cases.

The museum was the brainchild of Oregon’s star epidemiologist William Keene, who died suddenly at the end of 2013. He cracked dozens, if not hundreds of outbreaks that sickened people from Portland, Oregon to Portland, Maine with food tainted by E. coli, salmonella, norovirus, campylobacter and listeria. He worked with manufacturers and health officials alike with one goal in mind: prevent consumers from getting sick.

He collected packages of tainted items in outbreaks he worked on and other public health officials sent him containers from their investigations. The museum includes items from the 1999 salmonella outbreak traced to alfalfa sprouts, the 2006 E. coli outbreak involving spinach and the 2012 E. coli outbreak traced to raw milk.

Dr. Paul Cieslak, medical director of Oregon’s immunization program, said the museum is designed to educate younger epidemiologists about the significance of past outbreaks and how they influenced public health decisions and epidemiological investigations.

“It’s mainly meant to be instructure,” Cieslak said.

The items are open to public health students and school groups by appointment. The website includes more extensive information on 12 outbreaks.

I believe the epidemiologists: Boise restaurant linked to Salmonella cases

Last week I spent some time with an old friend who owns a funeral home. Fifteen years ago we spent our time and extra money in the local pub drinking pints and talking trash. As we’ve gotten older our taste has changed; we discussed our chosen professions over a bottle of wine.

As we chatted food safety and death he wanted to know how the disease detectives connected the dots in an outbreak. I gave him a rudimentary explanation of PFGE, genome sequencing, Pulsenet and told him about Bill Keene’s contribution to foodborne epidemiology. He was genuinely interested in learning about how epi folks do their magic, or it may have been the wine.101821776

Here’s today’s example of a cluster of illnesses linked to a restaurant, without a smoking gun, that is garnering further investigation (via the Idaho Statesman).

Five people have reported getting sick from Salmonella poisoning since late February after eating at a Boise restaurant, according to the Central District Health Department.

The agency did not publicly name the eatery Monday, but the owner of Pho Tam on North Orchard Street confirmed to the Idaho Statesman that her Vietnamese restaurant is the one in question.

“I don’t know what happened,” owner Long Doan said. “We try to be careful.”

The most recent sickness took place in mid-March, but wasn’t reported to health officials until Thursday, Health Department spokeswoman Christine Myron said.

Health inspectors last week tested food at the restaurant and did not find any traces of Salmonella or other harmful bacteria, Myron said.

“The cultures that they grew did not come back with any Salmonella, so they’ve not determined a definite source for the Salmonella,” Myron said. “We don’t know exactly how it may have gotten into the food at this point.”

I trust the epi folks.


Problems public health investigators face: It’s a tough job (but we love ya for it)

In Ontario, Canada (that’s in Canada), enteric case investigators perform a number of functions when conducting telephone interviews including providing health education, collecting data for regulatory purposes ultimately to prevent further illness, enforcement, illness source attribution and outbreak detection. Information collected must be of high quality as it may be used to inform decisions about public health actions that could have significant consequences such as excluding a person from work, recalling a food item that is deemed to be a health hazard, and/or litigations. The purpose of this study was to describe, from the perspectives of expert investigators, barriers experienced and the techniques used to overcome these barriers during investigation of enteric disease cases (that’s Sider, right, exactly as shown).


Twenty eight expert enteric investigators participated in one of four focus groups via teleconference. Expert investigators were identified based on their ability to 1) consistently obtain high quality data from cases 2) achieve a high rate of completion of case investigation questionnaires, 3) identify the most likely source of the disease-causing agent, and 4) identify any possible links between cases. Qualitative data analysis was used to identify themes pertaining to successful techniques used and barriers experienced in interviewing enteric cases.


Numerous barriers and strategies were identified under the following categories: case investigation preparation and case communication, establishing rapport, source identification, education to prevent disease transmission, exclusion, and linking cases. Unique challenges experienced by interviewers were how to collect accurate exposure data and educate cases in the face of misconceptions about enteric illness, as well as how to address tensions created by their enforcement role. Various strategies were used by interviewers to build rapport and to enhance the quality of data collected.


To our knowledge, this is the first study to examine the perspectives of expert enteric disease case investigators on successful interview techniques and barriers experienced during enteric case investigation. A number of recommendations could improve the process of enteric case investigation in the Ontario context which include formal training and development of resource materials pertaining to interviewing, standardized interviewing tools, strategies to address cultural and language barriers, and the implementation of the single interviewer approach.

A focus group study of enteric disease case investigation: successful techniques utilized and barriers experienced from the perspective of expert disease investigators

BMC Public Health, Disease epidemiology- infectious, Volume 14, doi:10.1186/1471-2458-14-1302

Stanley Ing, Christina Lee, Dean Middleton, Rachel D Savage, Stephen Moore and Doug Sider


To the importer who says there’s no proven link, I say, epidemiology still works: 18 confirmed sick with hep A from frozen Chinese berries

As the number of confirmed hepatitis A cases in Australia from frozen berries grown in China rose to 18 over the weekend, as political rhetoric about imports and local food reached staggering new heights, the company continued to insist there’s no firm link between a national hepatitis A outbreak and its recalled berries.

epidemiology.WATER PUMP3_Page_4The company says its imported Chinese berries were recalled on health department advice despite a lack of proof from accredited laboratories of a link to the hepatitis A virus (HAV).

“At this point, we have not been provided any remaining consumer product to test from the 13 confirmed HAV cases to clinically verify there is indeed a link with the Nanna’s Mixed Berries,” managing director and chief executive Stephen Chaur said in a statement on Friday.

Mr Chaur said the company had rigorous testing that went beyond the Australian standards requirement that five per cent of imported fruit containers be tested.

“Patties Foods’ documented test regime is among the highest, testing 20 per cent of all the containers when they arrive in Australia,” he said.

But Mr Chaur said sample testing for microbial and viral markers had been increased to 100 per cent of imported frozen berries from all countries.

The company has checked quality control testing documents back to June 2014 and says they’re satisfied no biological indicators outside Australian guidelines have been detected.

Great. Prove it and make the data public.

Importance of epi: Outbreak of diarrheal illness caused by Shigella flexneri — American Samoa, May–June 2014

The U.S. Centers for Disease Control reports that on May 9, 2014, a physician at hospital A in American Samoa noticed an abnormally high number of children presenting to the emergency department with bloody diarrhea.

American Samoa.schoolBased on preliminary testing of stool specimens, Entamoeba histolytica infection was suspected as a possible cause. Shigella was also suspected in a subset of samples. On May 22, the American Samoa Department of Health requested assistance from CDC with the outbreak investigation. The goals of the investigation were to establish the presence of an outbreak, characterize its epidemiology and etiology, and recommend control measures. The CDC field team reviewed the emergency department log book for cases of diarrheal illness during April 15–June 13, 2014. During this period, 280 cases of diarrheal illness were recorded, with a peak occurring on May 10. Twice as many cases occurred during this period in 2014 compared with the same period in 2011, the most recent year for which comparable surveillance data were available. Cases were widely distributed across the island. The highest number of cases occurred in children aged 0–9 years. Across age groups, cases were similarly distributed among males and females. These patterns are not consistent with the epidemiology of disease caused by E. histolytica, which tends to cause more cases in males of all ages.

Hypothesis-generating interviews with families of 13 patients did not reveal any common water, food, sewage, or event exposures. Eight participants reported having ill household contacts, with family contacts often becoming ill within 1–3 days after the participant’s illness onset. Six stool specimens were sent to CDC. All were negative for ameba, including E. histolytica, by multiple laboratory methods. All six specimens were also negative for Cryptosporidium and Giardia by a polymerase chain reaction test. However, an invasion plasmid antigen H (ipaH) gene sequence, a genetic marker of Shigella, was identified in four specimens. Additionally, seven Shigella isolates sent to the Hawaii Department of Health and CDC were identified as Shigella flexneri serotype 7 (proposed; also referred to as provisional 88-893 or 1c), and five shared an indistinguishable pulsed-field gel electrophoresis pattern.

american.samoa.peopleShigella causes an estimated 500,000 cases of shigellosis per year in the United States (1). Most persons infected with Shigella develop diarrhea (sometimes bloody), fever, and stomach cramps 1–2 days after they are exposed to the bacteria. The illness usually resolves in 5–7 days. Careful and frequent hand washing and strict adherence to standard food and water safety precautions are the best defense against shigellosis (2).

Together, epidemiologic and laboratory data suggest this was a shigellosis outbreak with person-to-person transmission. This investigation highlights the importance of building epidemiologic and laboratory capacity for enteric illnesses and enhancing basic hand hygiene and prevention strategies in U.S. territories.

Lesson in epidemiology (not): Wisconsin farmer says raw milk may not have made Durand football team ill

Now that the Reed ranch has been named and shamed as the source of the raw milk linked to at least 38 illnesses of Campylobacter jejuni related to players and staff of the Durand High School football team, the owner is speaking out.

raw.milk.death.1917Diana Reed, whose farm provided the milk said, “Some people got sick who did not drink the milk,” she said Saturday.

State health officials also tested manure of the cows at the Reed ranch and concluded some of the cows contained the strain of Campylobacter that sickened the students.

On Friday, state health officials identified the Reed farm as the source of the milk following an open records inquiry by the Milwaukee Journal Sentinel.

But Reed said there could have been other sources of the bug.

“I discussed it with the epidemiologist in Madison. He gave me some statistics — 56 people ate chicken, 38 got sick; 43 people chose to drink milk and 33 got sick,” she said. “They interviewed everyone who was there.”

That leaves five people who did not drink milk, but who still had Campylobacter.

Epidemiology, just trying to do this jigsaw puzzle: Outbreak of E. coli O157:H7 associated with lettuce served at fast food chains in the Maritimes and Ontario, Canada, Dec 2012

Background: Identification and control of multi-jurisdictional foodborne illness outbreaks can be complex because of their multidisciplinary nature and the number of investigative partners involved.

spongebob.oil.colbert.may3.10Objective: To describe the multi-jurisdictional outbreak response to an E. coli O157:H7 outbreak in Canada that highlights the importance of early notification and collaboration and the value of centralized interviewing.

Methods: Investigators from local, provincial and federal jurisdictions, using a national outbreak response protocol to clarify roles and responsibilities and facilitate collaboration, conducted a rapid investigation that included centralized re-interview of cases, descriptive methods, binomial probability, and traceback findings to identify the source of the outbreak.

Results: There were 31 laboratory confirmed cases identified in New Brunswick, Nova Scotia, and Ontario. Thirteen cases (42%) were hospitalized and one case (3%) developed hemolytic uremic syndrome; there were no deaths. Due to early notification a coordinated investigation was initiated before laboratory subtyping was available. Re-interview of cases identified 10 cases who had not initially reported exposure to the source of the outbreak. Less than one week after the Outbreak Investigation Coordinating Committee was formed, consumption of shredded lettuce from a fast food chain was identified as the likely source of the illnesses and the implicated importer/processor initiated a precautionary recall the same day.

Conclusion: This outbreak investigation highlights the importance of early notification, prompt re-interviewing and collaboration to rapidly identify the source of an outbreak.

Canada Communicable Disease Report CCDR

Tataryn J, Morton V, Cutler J, McDonald L, Whitfield Y, Billard B, Gad RR and Hexemer A