Epidemiology - Campylobacter

Epidemiology

Campylobacter infections are extremely common worldwide.

◗ Geographical distribution

The true incidence of Campylobacter infections is not known, because they are non-notifiable diseases. In the United States, an estimated 2 million cases of Campylobacter enteritis occur every year, which constitute 57% of cases of gastroenteritis. Average incidence of Campylobacter bacteremia in developed countries is estimated to be 1.5/1000 patients with enteritis. In developing countries, although exact figures are not available, C. jejuni is frequently isolated from stool of healthy childrenduring 5 years of life. Isolation rates in children ranges from 8% to 45% with an annual incidence as high as 2.1 episodes of Campylobacter-associated diarrhea per child.

◗ Habitat

In infected humans, C. jejuni inhabits the duodenum, jejunum, and colon. C. fetus inhabits the genital tract of infected mothers.

◗ Reservoir, source, and transmission of infection

Campylobacter infections are zoonotic. Infected animals arethe main reservoir of the infection. The animal reservoirs are the dogs, cats, and other pets that carry the organism in their gastrointestinal tract. Infected animal food products are the source of infection. Transmission of C. jejuni to humans occurs by the following methods:

1.        Transmission occurs most commonly from infected ani-mals and their food products. Most human infections occur by ingestion of contaminated and improperly cooked poultry meat products. Infected chickens may account for 50–70% of the infection. The infection also occurs by drinking contaminated raw milk or unpasteurized milk.

2.        The infection may also be transmitted from infected ani-mals and humans by feco-oral route on ingestion of food and water contaminated with human or animal feces.

3.        The infection may be transmitted from person to person by sexual contact.

Campylobacter infection occurs in all age groups. In developingcountries, Campylobacter enteritis is very common in children younger than 5 years. In contrast, Campylobacter bacteremia occurs in patients older than 65 years. Campylobacter enteritis is much frequently seen in (a) individuals handling cattle, sheep, and other farm animals, (b) homosexual men, and (c) labora-tory workers.Campylobacter bacteremia is seen in (a) persons with immunocompromised state (hypogammaglobulinemia, HIV infection, malignancies, etc.), (b) persons with diabetes mellitus and alcoholism, and (c) pregnant ladies.