Although Salmonella infections decreased by 9
percent in 2013, illnesses caused by other foodborne bacteria rose
by as much as 32 percent.
Each year, the most common foodborne illness — Salmonella — sickens
about 1.2 million people in the U.S. and results in 450 deaths,
according to the CDC. Recent efforts to lower that number seem to be
working, but illnesses caused by contaminated food are still too
common, say the report's authors.
"Progress in preventing foodborne illnesses has been limited in
recent years," said senior author Olga L. Henao of the National
Center for Emerging and Zoonotic Infectious Diseases at the CDC in
Atlanta. "More can be done."
The Foodborne Diseases Active Surveillance Network, a collaboration
between federal health administrations and state health departments,
monitors infections linked to food caused by nine common pathogens
at 10 sites in the U.S. The new report includes 2013 infection data
and trends since 2006.
In 2013, there were 19,056 lab-confirmed infections in the sample
areas, which was not significantly different from 2006. More than
4,000 people were hospitalized and 80 died from foodborne illnesses.
The most common infections in 2013 were Salmonella, affecting 15
percent of the population; Campylobacter, affecting 14 percent and
Shigella, affecting 5 percent, according to the results published in
the CDC's Morbidity and Mortality Weekly Report (MMWR).
All the bacterial infections can originate in contaminated food,
including raw meat, especially if food handlers do not maintain
strict hand hygiene.
Most of the bacteria are also found in human fecal matter, which
explains why the infections are most common in children under five
years old, including toddlers who are not fully toilet trained.
Salmonella infections decreased by 9 percent between 2010 and 2012,
but one less common infection, Vibrio, increased by 32 percent. The
Vibrio family of bacteria includes the strain that causes cholera.
The microbes are usually found in salt water and may contaminate
undercooked seafood or enter wounds on a swimmer's body.
According to the new report, Vibrio infected 0.5 percent of the
population in 2013.
Unlike most of the other infections, Vibrio was most common among
people over age 65.
"Vibrio infections are rare but often serious," Henao told Reuters
Health in an email. "We estimate that 50 to 60 percent of U.S.
Vibrio infections are acquired through food, many of these are due
to eating raw oysters."
Because Vibrio bacteria live in oceans, climate change could play a
role in their becoming increasingly common, she said.
"Vibrio bacteria multiply when seawater where oysters grow is warm,"
Henao said. "As a result, these infections are most common during
the warm months, when waters and oysters contain higher numbers of
In a separate report in the same issue of MMWR, researchers describe
more than 100 cases in 2013 of people in Atlantic coastal areas made
ill by a Vibrio strain previously associated only with Pacific
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Infections by foodborne Vibrio can usually be prevented by
rapidly refrigerating oysters after harvest and with thorough
cooking, especially when the oysters come from warm waters, but
these measures have not been sufficiently implemented, she Henao
Salmonella numbers may be falling because it is relatively easy
to identify sources and routes of transmission of outbreaks, said
Diane Newell, a microbiologist who established the Food-borne
Zoonoses Consultancy in Andover, U.K.
In Europe, monitoring and regulating food production has
successfully lowered Salmonella infections, Newell told Reuters
Health by email, but another bacterium found in poultry,
Campylobacter, has been harder to control.
"The numbers of campylobacterosis cases continue to rise year on
year in most countries that undertake monitoring," and it is not
clear why the numbers keep going up, she said.
"We need research to help the poultry industry control and prevent
Campylobacter-positive flocks — for example vaccines or other
approaches to complement on-farm biosecurity," she said. "But the
good news is Campylobacter are killed by cooking."
Efforts to decrease infections originating in food, Henao said,
generally should focus on preventing contamination at the growing,
harvesting and processing stages, monitoring contaminants in
imported foods and educating food handlers in restaurants and
consumers about risks and prevention measures.
"Overall, pregnant women and their newborn infants, older adults and
people with weakened immune systems are at higher risk for acquiring
many infections," which are also the groups that can have the most
serious complications, including miscarriage or death, Henao said.
To prevent infections, food handlers should adhere to the basic
steps "clean, separate, cook and chill," she said. That means
washing hands, cutting boards and utensils and keeping raw meat and
fish separate from ready-to-eat foods.
Whole cuts of meat should be cooked to an internal temperature of
145 degrees Fahrenheit, 160 degrees for ground meat, and 165 degrees
for all poultry. Refrigerators should be kept below 40 degrees, she
Morbidity and Mortality Weekly Report, April 18, 2014.
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