Cattle as a potential source of Campylobacter infections


<p>The reported incidence of enteric infections caused by campylobacteria, in particular <em>Campylobacter jejuni</em>, is higher than for any other intestinal infection in Finland. On an annual basis, most sporadic infections in humans are of foreign origin, but a notable proportion of summer infections are domestically acquired. While chickens have been the major individual source of campylobacters in most countries, in Finland the prevalence of campylobacters in chicken slaughter batches is among the lowest in Europe.</p>

Cattle as campylobacter carriers
The prevalence of campylobacters in cattle was studied in an extensive slaughterhouse survey and in a one-year study of three Finnish dairy cattle farms. Almost a third of slaughter cattle were carriers of campylobacters, beef cattle more often than dairy cattle. However, campylobacters were rarely detected in bovine carcass samples. On dairy cattle farms, bovine animals appeared to be long-term, possibly permanent carriers of campylobacters. However, marked differences in the excretion of these bacteria were detected between cattle herds and individual animals.

Good hygiene can limit the occurrence of campylobacters
Compliance with good milking hygiene standards can prevent the campylobactercontamination of raw milk. At cowsheds, contamination of water troughs with bovine faeces can maintain the colonisation of campylobacters in cattle. Maintaining the cleanliness of water troughs may restrict the circulation of campylobacters among cattle during indoor housing. When put out to pasture, the environment, natural waters in particular, can serve as a source of campylobacters for cattle.

Finnish cattle and chickens as sources of human campylobacter infection
The role of cattle as a source of human campylobacter infections was studied by comparing the prevalence of four genes in C. jejuni isolates from cattle, chickens and patients in southern Finland, primarily representing the urban population. In addition, the genotypes of C. jejuni isolates were compared in a nationwide study.

The results corroborate indications by previous studies of host-adapted C. jejuni strains i.e. genetic adaptation of campylobacters to different host animals. They also indicate that sources of campylobacters in infections of rural and urban population differ from one another.

Alongside chickens, cattle may be a major source of campylobacters in domestic human infections, particularly in rural areas. However, food is probably a minor route of transmission of C. jejuni strains from cattle to humans.

Read the résumé  (pdf, 15 kb) on Marjaana Hakkinen’s doctoral thesis Finnish cattle as reservoir of Campylobacter spp. (pdf, 897 kb)

For more information, please contact:
Researcher Marjaana Hakkinen, Microbiology Research Unit
tel. +358 400 287 417, marjaana.hakkinen at-merkki.gif : 1Kb

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