Sep 28, 2011 (CIDRAP News) Seventeen more listeriosis infections, along with five more deaths, have been linked to a multistate outbreak tied to a Colorado farm's tainted cantaloupes, pushing the total to 72 illnesses and 13 deaths, the US Centers for Disease Control and Prevention (CDC) said yesterday.
At a press briefing today, CDC director Tom Frieden, MD, said two of the sick patients are pregnant women, and so far the infections aren't posing a serious threat to the women or their fetuses. Pregnant women are among those vulnerable to listeriosis infections, along with older people and those who have weakened immune systems.
The Listeria monocytogenes outbreak is the deadliest one in the country in nearly a decade, because listeriosis is highly lethal in susceptible groups, he said.
Frieden said that although the cantaloupes have been recalled and are nearing the end of their shelf life, federal officials worry that some of the affected products could still be in people's refrigerators, where Listeria, unlike other foodborne pathogens, can flourish even in cold conditions.
He advised people to check the labels before consuming cantaloupes, and advised them to dispose of the products if the source can't be determined from the label or by asking suppliers.
The outbreak toll is expected to climb higher, because several other states and local health departments are investigating if their listeriosis cases are connected to the outbreak. CDC said it expects to receive reports of additional cases through October, because the incubation period for the disease is long, and patients can get sick with listeriosis up to 2 months after eating contaminated food.
Four more statesFlorida, Kansas, Missouri, and North Dakotareported their first outbreak-related Listeria infections, pushing the number of affected to states to 18, said the CDC.
At least 25 states received shipments of the Rocky Ford region cantaloupes from Jensen Farms, which recalled its products on Sep 14 after testing revealed the outbreak strain on its cantaloupes and on equipment at its Granada. Colo., facility. That total is eight states more than in the CDC's previous update on Sep 21. The products could have also been further distributed, the CDC said.
Federal officials said today that the Listeria outbreak is the first of its kind in whole cantaloupes, though the fruit has been linked to 10 foodborne illness outbreaks in the pastseven that involved Salmonella and three linked to norovirus.
Sherri McGarry, MD, senior advisor in the Food and Drug Administration (FDA) office of foods, told reporters that a team of federal and state experts are at Jensen Farms conducting an environmental assessment to explore how contamination occurred and what opportunities the pathogen had for continued growth. She said they will be looking at the potential role of animal reservoirs.
The CDC has said the outbreak involves four strains of Listeria, which typically causes invasive infection that can spread to the bloodstream or other body sites.
Barbara Mahon, MD, deputy branch chief with the CDC's enteric disease branch, said it's unusual to see four stains involved in an outbreak, and that they aren't closely related, falling into two different serotypes. "The reasons for that are under investigation," she said.
The infectious dose for Listeria isn't well understood and may vary by individual, based on underlying health status, she said.
In other related developments, Kansas food processor Carol's Cuts on Sep 23 recalled 594 pounds of fresh-cut cantaloupe due to possible Listeria contamination. The company's action is related to the larger Jensen Farms cantaloupe recall, the FDA said in its recall notice. The Carol's Cuts products were packaged in 5-pound trays and included in 8-ounce fruit medley that was distributed to institutions and restaurants in Kansas, Missouri, and Nebraska.
Meanwhile, Caroline Smith DeWaal, food safety director of the Center for Science in the Public Interest (CPSI), yesterday urged the FDA to rapidly release new guidelines and regulations for the production of safe produce, which are due for release in January 2012 and January 2013, respectively. In a statement, she called on Congress to fully fund the FDA Food Safety Modernization Act to prevent similar outbreaks.
Sep 27 CDC outbreak update
Sep 23 FDA recall notice
Sep 27 CSPI press release