| Clinical
Features |
Manifestations are host-dependent.
In elderly and immunocompromised persons, sepsis and meningitis
are the main presentations. Pregnant women may experience
a mild, flu-like illness followed by fetal loss or bacteremia
and meningitis in their newborns. Immunocompetent persons
may experience acute febrile gastroenteritis. |
| Etiologic
Agent |
Listeria monocytogenes, a
gram-positive rod-shaped bacterium. |
| Incidence |
Last estimated at 2500 cases annually
in the United States, based on data through 1997 (but see
Trends below). |
| Sequelae |
Last estimated at 500 fatal cases
annually in the United States, based on data through 1997
( but see Trends below). |
| Transmission |
Contaminated food. Rare cases of
nosocomial transmission have been reported. |
| Risk
Groups |
For invasive disease: immunocompromised
individuals, pregnant women and their fetuses and neonates,
and the elderly. |
| Surveillance |
Active laboratory- and population-based
surveillance in FoodNet. Listeriosis was added to the list
of nationally notifiable diseases in 2001. To improve surveillance,
the Council of State and Territorial Epidemiologists has recommended
that all L. monocytogenes isolates be forwarded to
state public health laboratories for subtyping through the
National Molecular Subtyping Network for Foodborne Disease
Surveillance (PulseNet).
At least 46 states have regulations requiring health care
providers to report cases of listeriosis. |
| Trends |
The annual incidence of listeriosis
decreased by 44% between 1989 and 1993; an analysis of the
incidence trend from 1996 to 2002 revealed a 38% decline.
However, outbreaks continue to occur. In 2002, an outbreak
that resulted in 54 illnesses, 8 deaths, and 3 fetal deaths
in 9 states was traced to consumption of contaminated turkey
meat. |
| Challenges |
Improve the safety of processed
meats through meticulous in-plant sanitation and post-packaging
pasteurization; intensify education efforts for high-risk
consumers to reduce their risk of listeriosis. |
| Opportunities |
Improve detection of dispersed outbreaks
through PulseNet;
compare subtypes of L. monocytogenes strains isolated
from human cases with those isolated from recalled foods;
determine the infectious dose through analysis of foods implicated
in outbreaks; look for L. monocytogenes as a cause
of outbreaks of febrile gastroenteritis where no other pathogens
are identified. |
|
December 2003
|
