into animal disease
Source of Article: http://www.farminguk.com/news/Finland--Research-into-animal-disease.13160.asp
FINLAND - Campylobacteriosis is the most commonly reported bacterial enteric
infection worldwide. The human cases are usually sporadic, and most of them
are caused by Campylobacter jejuni, says Evira.
In Finland, about 30 per cent of infections are domestically acquired, but in
the summer months the proportion of domestic infections is nearly 70 per
cent. The incidence peaks annually in July-August.
is considered the most important source of campylobacters
in sporadic infections. On the other hand, evidence from recent studies
suggests that poultry
is less significant than is generally thought, and also
other animals can be considered notable reservoirs of campylobacters. Cattle
are well-known carriers of campylobacters, but these bacteria are rarely
detected in beef. Instead, outbreaks attributed to consumption of
unpasteurized milk have been reported from several countries.
The campylobacter monitoring of chicken slaughter batches is compulsory since
June 2004 in Finland. All slaughter batches from June to October are sampled,
and during the rest of the year, sampling is performed according to a
specific sampling plan. The campylobacters isolated by the slaughterhouse
laboratories are identified at Evira.
In a project of Evira and the University of Helsinki, Evira examined the
prevalence of campylobacters in chicken slaughter batches, and the genotypes
of campylobacters isolated from chicken rearing halls and slaughter batches
were compared with PFGE, as well as the genotypes of isolates from breeders
and their progeny. The campylobacters in cattle were examined in an extensive
slaughterhouse survey, and on three dairy cattle farms. Comparison of
genotypes of C. jejuni isolates from chickens, cattle and domestically
acquired human cases in summer 2003 was carried out in co-operation with THL
(formerly KTL) and the poultry
C. jejuni is the most common campylobacter species in chickens and cattle.
During the five-year monitoring, the prevalence of campylobacters in chicken
slaughter batches has consistently peaked in July-August, but even then it
has been lower than in most other countries. Usually only one campylobacter
genotype is detected. Furthermore, a proportion of birds can be
campylobacter-negative in a campylobacter-positive slaughter batch. The
transmission of campylobacters from breeders to chickens seems unlikely.
The prevalence of campylobacters in Finnish cattle was also lower than in
many other countries, and the occurrence of campylobacters in carcasses was
rare. The Finnish beef can be considered a minor source of campylobacters. In
the dairy cattle study, the same genotypes of C. jejuni persisted in the
herds throughout the study, and new types occurred only occasionally. The
resistance to campylobacter colonisation seemed to vary among animals. Campylobacters
were not detected in milk samples.
More than half of the human C. jejuni isolates in summer 2003 represented
identical genotypes with chicken and cattle isolates. Less than one third of
the human cases were temporally associated with campylobacter isolates from
chickens. Chickens can be considered the most important single source in
domestically acquired sporadic infections in Finland. The significance of
cattle can be notable especially in rural areas, where the environmental
routes may be more important than food in transmission of campylobacters.