Listeriosis has an incubation period of up to 70 days, so additional cases are expected to emerge. Because officials determined that 9 percent of the cases involved a different strain of listeria, there may be multiple outbreaks.
Doctors in South Africa were not required to report cases of listeriosis to the Ministry of Health until last December. Patient records were vague and often lacked the contact information for follow-up, said Dr. Peter K. Ben Embarek, a food safety expert at the W.H.O.
“Many didn’t even know to be asking patients about the meat,” said Dr. Louise Ivers, an associate global health professor at Harvard. “Surveillance is a critical but neglected piece of health systems,” Dr. Ivers said. “Without the resources and lab infrastructure, countries are left reacting: reacting to cholera, reacting to Ebola, reacting to listeria.”
Richard Spoor, a lawyer in South Africa, has filed a $2 billion lawsuit against Tiger Brands. Nearly 70 victims and family members are part of the suit, according to William D. Marler, a Seattle-based food safety lawyer who is a consultant on the case.
The flulike symptoms of listeriosis — fevers, vomiting and diarrhea — most often affect the elderly, immune-compromised individuals and pregnant women, who can pass it on to their fetuses. Pregnant women are 10 times more likely than other people to become infected, according to the Centers for Disease Control and Prevention. About 42 percent of the cases in this outbreak were newborns infected during gestation, the W.H.O. said.