On Saturday, Nov. 14, the County of San Luis Obispo Department of Public Health reported a new E. coli O157 infection in a person who never visited Brookshire Farms. The county believes the infection was passed person to person at a preschool in San Luis Obispo, from one of the five people confirmed ill after visiting the farm in October. The new patient developed hemolytic uremic syndrome (HUS), was hospitalized, and is now recovering at home.
This is the outbreak the county closed on Nov. 6 with five laboratory-confirmed cases and 10 suspect cases, and in which it confirmed a death on Nov. 10. The file was closed. The outbreak was not.
What The Tribune has reported
The county has released almost nothing about the people who were sickened. The San Luis Obispo Tribune has filled in some of it.
- The person who died was an 18-month-old girl. Her grandmother told The Tribune that the child visited Brookshire Farms with her family in mid-October, became ill a few days later, developed HUS, spent 10 days at Stanford’s Lucile Packard Children’s Hospital, and died on Nov. 4. That was two days before the county closed its investigation and six days before it confirmed a death.
- A 6-year-old boy from Nipomo was still hospitalized more than three weeks after he got sick. The Tribune reported that he visited the farm on Oct. 17, had symptoms by Oct. 20, was admitted to a Santa Maria hospital the next day, and was transferred to Stanford on Oct. 27 with kidney failure and other complications.
- No source was ever identified. The Tribune reported that environmental testing did not find the O157 strain that made people sick, and that the county listed corn cups, pumpkins, hay and non-potable water among the exposures the patients had in common.
The county reported three people with HUS among the farm cases on Oct. 30. The preschool case is a fourth, in someone who was never there.
What the county has said
- The infection is laboratory-confirmed E. coli O157, confirmed by the county Public Health Laboratory after the patient’s medical provider reported it.
- The person did not visit Brookshire Farms.
- The county calls it secondary, person-to-person transmission from one of the five primary cases, and says the transmission is thought to have occurred at the preschool.
- The person developed HUS, was hospitalized, and is recovering at home.
- Families were notified, cleaning was started, and the affected classrooms will be closed Monday, Nov. 16.
- Doctors heard first. The county’s provider notice carrying the same facts is dated Nov. 13.
The county has not given the patient’s age, the name of the preschool, the date the illness began, whether the isolate has been sequenced against the five farm cases, or whether the confirmed count now stands at six.
What is a secondary case of E. coli?
A primary case is a person infected at the source: the hamburger, the lettuce, the petting zoo. A secondary case is a person who never touched the source and caught the infection from someone who did. Shiga toxin-producing E. coli (STEC) leaves the body in stool, and it takes very little to make the next person sick. Researchers put the infectious dose at roughly 100 organisms. A diaper change, a shared toilet, a toy that goes from one mouth to another, or a hand that was not washed is enough.
How common are secondary E. coli cases?
More common than most people think.
- About one in five outbreak cases. A review of 90 E. coli O157 outbreaks in the United States, Canada, Britain, Ireland, Scandinavia and Japan found that secondary cases averaged 19.5 percent of the cases in an outbreak.
- About one in nine of all cases. Ten years of whole-population surveillance in Scotland classified 11 percent of E. coli O157 cases as secondary.
- Just as severe. The same research found that people infected secondhand face a risk of HUS similar to people infected at the source. The San Luis Obispo case is the proof.
Where do secondary cases happen?
Two places, over and over: child care and the home.
The 90-outbreak review found significantly higher secondary rates in outbreaks where the median patient was younger than 6 and where the spread ran through nurseries. A Japanese study of 16 day care STEC outbreaksmeasured household spread from zero to 34.4 percent, with a median of 4.4 percent. Siblings aged 6 to 9 were infected most often, and mothers more often than fathers. In England, secondary cases turned up in 7 percentof the child care settings attended by an infectious child.
There is a near-identical precedent. In a 2014 Kansas E. coli O157 outbreak, a child with a mild illness passed the infection to another child in a home day care. The second child developed HUS. And this is not new. When CDC wrote up the 1993 Jack in the Box outbreak, it reported that secondary transmission in families and child day care settings was under investigation.
Why a new case can surface nearly four weeks after the farm visits
All five confirmed patients visited Brookshire Farms on Oct. 17 or 18. The provider notice went out Nov. 13. The gap is explained by how long children carry the bacteria. In the English study, children shed STEC for a median of 31 days, and 24 percent were still shedding at six weeks or longer. A child can feel fine, look fine, and still be infectious.
That is why public health departments keep infected children out of group care. The California Department of Public Health tells local health departments that, because of the low infectious dose, they may need to restrict people with STEC from day care until the department has examined and cleared them.
Questions the county should answer
- Is the confirmed count now six, and has the new isolate been matched by whole genome sequencing to the five farm cases?
- When did the new patient become ill?
- Did the primary case attend the preschool while still shedding, and was that person cleared by Public Health before returning?
- Have classmates and staff in the affected classrooms been tested, or only told to watch for symptoms?
- Were the families of the 10 suspect cases given the same exclusion instructions as the five confirmed ones?
None of this is about blame for a preschool that, by the county’s account, has cooperated. It is about whether the next secondary case can be prevented.
What families should do
- Call a doctor right away if a child has bloody diarrhea or severe stomach cramps, and say that the child may have been exposed to E. coli O157.
- Watch for signs of HUS in the week or two after diarrhea starts: less urination, pale skin, unusual tiredness, easy bruising.
- Keep a sick child home from preschool or day care, and do not send the child to a different one.
- Wash hands with soap and water after every diaper change and bathroom trip. At home, that includes brothers, sisters and parents.
Secondary cases and the law
A person who never touched the source has the same legal claim as a person who did. My firm tried that question to a jury and defended it on appeal. In Almquist v. Finley School District No. 53, 114 Wn. App. 395, 57 P.3d 1191 (2002), ten children at Finley Elementary in eastern Washington were infected with E. coli O157:H7 after a 1998 school taco lunch. The eleventh plaintiff, and the most seriously injured, was a two-year-old who did not attend the school and never ate the meal. She had spent time with two children who did, one of them a confirmed case, and the health district’s investigators classified her as a secondary case. The school district argued on appeal that the jury had too little evidence to tie her illness to the lunch. The Washington Court of Appeals disagreed. It held that the facts fit the experts’ description of a typical secondary infection, that the district had offered no plausible alternative explanation, and that the jury could reasonably find the tainted meal caused her illness. The verdict stood, and the Washington Supreme Court declined review in 2003. The reasoning is simple and it travels: person-to-person spread is a known, predictable consequence of an E. coliO157 outbreak, and the law treats a predictable injury as one the source is responsible for. A child infected at a preschool by a classmate who was infected at a farm stands in the same place that two-year-old stood.
More on preventing illness at farms, fairs and petting zoos is at fair-safety.com.
Marler Clark represents two families sickened in the Brookshire Farms outbreak. More about E. coli infections and HUS is on the firm’s site.
Recent Comments