Campylobacter jejuni is found in the intestinal tract
of turkeys, chickens, sheep, cattle, and other farm animals and
birds, all of which serve as reservoirs of infection. Contamination
of meat, especially chickens, during slaughter may be the way bacteria
enter the human food chain. The main source of C jejuni and C
coli infection in humans is poultry, although unpasteurized
milk, water, dogs, cats, hamsters, and ferrets are potential sources.
In the United States, an estimated 2 million cases of campylobacteriosis
occur each year. It is the most common bacterial cause of food-borne
illness.1 The overall incidence of laboratory-confirmed Campylobacter infection
in 2007 in the United States was 12.7 cases per 100,000 population,
representing a 31% decrease since 1996.3-5 However,
the incidence of symptomatic Campylobacter species
infection has been estimated at 760 to 1100 cases per 100,000 populations.2,3 Age-specific
rates of Campylobacter jejuni isolation in patients with
diarrhea differ among countries. In industrialized countries, C
jejuni is isolated from 5% to 16% of
children with diarrhea, with a prevalence of infection in healthy
children of up to 1.5%.1 The disease occurs
in all ages but is more common in children less than 5 years of
age, with a second peak at 15 to 29 years of age. In children under
5 years of age, the incidence of laboratory-confirmed Campylobacter species
infection is 43.4 cases per 100,000 person-years (up to 54.3 cases
per 100,000 person-years in children < 1 year of age), and the
associated male-to-female ratio is 1.34:1.6 It
is the third most common cause of hospitalization for gastroenteritis
after rotavirus and Salmonella species infection,
with a hospitalization rate of 10.8% for all Campylobacter species
infections.7-9 Studies of the disease burden of Campylobacter species
infection in the Netherlands have estimated that intestinal infection
in general accounts for 67,000 disability-adjusted life years per
year, and that Campylobacter species infections represent
at least one third of the disease burden of all intestinal infections.10 The
cost per case of gastrointestinal infection in Europe has been estimated
to be US$94 to US$132. In England, the total
cost of gastrointestinal infections was estimated to be US$1.23
billion each year. Of this amount, US$116 million is spent
on cases of Campylobacter species infection, the
highest cost associated with a particular pathogen (including rotavirus
and Salmonella).11Campylobacter species
infection is generally associated with mild illness and only occasionally
is fatal.12 The mortality rate associated with
symptomatic Campylobacter species infection has
been estimated at 24 deaths per 10,000 culture-confirmed cases or
200 deaths per year in the United States. In developing countries,
the isolation rate in children with diarrhea is 8% to 45%,
with a similar rate of isolation in asymptomatic children.13-16 Infections
occur early in life, with the highest proportion of C jejuni isolates
obtained from children under 5 years of age.13-15 The
annual incidence of Campylobacter species infections
can be as high as 2.1 episodes per child. Infections
acquired early in life are more likely to be associated with
diarrhea, whereas those occurring beyond the age of 4 years, although
relatively common, are mostly asymptomatic.14
Rates of C jejuni infection in the United States
peak in the summer and fall, but cases occur throughout the year.
Modes of transmission of Campylobacter differ between economically
developed and developing countries. In industrialized regions, most
sporadic cases can be attributed to the handling, preparation, and
consumption of contaminated raw or undercooked poultry.1,4,5,17,18 Common-source outbreaks
have occurred in schoolchildren following ingestion of unpasteurized milk.19 The
main factors involved in transmission in developing regions are
free-roaming poultry in the household, toddlers in the family, a
limited water supply, and lack of adequate disposal of excrement.
Transmission can be reduced substantially by education regarding
personal and domestic hygiene, penning of chickens outside the house, avoidance
of contact with their feces, piped water, flush toilets, and hand
washing.20C coli has
been isolated more frequently in populations with intimate contact
with swine. C jejuni subsp doylei is
isolated more often in socially deprived communities and in people
who have contact with cats and dogs. Perinatal human infections
due to C fetus have been related to maternal infections
during pregnancy or at the time of delivery. The incubation period
is usually 1 to 7 days, but it can be longer.