SUMMARYThe 2007-2009 human Q fever epidemic in The Netherlands attracted attention due to its magnitude and duration. The current epidemic and the historical background of Q fever in The Netherlands are reviewed according to national and international publications. Seroprevalence studies suggest that Q fever was endemic in The Netherlands several decades before the disease was diagnosed in dairy goats and dairy sheep.

Q fever is a zoonosis caused by the bacterium Coxiella burnetii. One of the largest reported outbreaks of Q fever in humans occurred in the Netherlands starting in 2007; epidemiologic investigations identified small ruminants as the source. To determine the genetic background of C. burnetii in domestic ruminants responsible for the human Q fever outbreak, we genotyped 126 C. burnetii–positive samples from ruminants by using a 10-loci multilocus variable-number tandem-repeat analyses panel and compared them with internationally known genotypes. One unique genotype predominated in dairy goat herds and 1 sheep herd in the human Q fever outbreak area in the south of the Netherlands. On the basis of 4 loci, this genotype is similar to a human genotype from the Netherlands. This finding strengthens the probability that this genotype of C. burnetii is responsible for the human Q fever epidemic in the Netherlands.

Transmission routes of Campylobacter spp. in broilers and possibilities for prevention of infections were studied on two Dutch broiler farms. The occurrence of Campylobacter spp. was studied in successive broiler flocks, in the environment of the farms and in some of the parent flocks involved. Isolates of Campylobacter spp. were typed by using randomly amplified polymorphic DNA (RAPD) analysis. The results indicate that broiler flocks become infected from environmental sources. The typing results suggest that on one farm transmission of Campylobacter spp. occurred from cattle to broilers via the farmer's footwear. After several campylobacter positive broiler cycles hygiene measures, including thorough cleaning and disinfection procedures, change of footwear at the entrance of each broiler house, control of vermin and other hygienic precautions, were introduced on both farms in order to prevent transmission of Campylobacter spp. from the farm environment to the broilers. The results indicate that the application of hygiene measures significantly reduced campylobacter infections of broiler flocks on both farms.

A method, including enrichment in Arcobacter Selective Broth (ASB) and isolation on semisolid Arcobacter Selective Medium (ASM) under aerobic conditions at 24 degrees C, is described for the isolation of Arcobacter from retail meat products. Selective agents used in ASB and ASM were cefoperazone, trimethoprim, piperacillin and cycloheximide. Arcobacters were isolated from 53 (24.1%) of 220 poultry meat products and also, at lower incidence from samples of beef and pork. The isolates were identified as A. butzleri or A. butzleri-like and belonged to a wide variety of serotypes and biotypes.

Shellfish from oyster farms in the Netherlands and imported from other European countries were examined for viral contamination. A method that allows sequence matching between noroviruses from human cases and shellfish was used. The samples of shellfish (n = 42) were analyzed using a semi-nested RT-PCR that had been optimized for detection of norovirus in shellfish (SR primer sets). In addition, a different genome region was targeted using a second primer set which is routinely used for diagnosis of norovirus infection in humans (JV12Y/JV13I). To improve the detection limit for this RT-PCR a semi-nested test format was developed (NV primer sets). One of 21 oyster samples (4.8%) from Dutch farms was norovirus positive, whereas norovirus was detected in 1 out of 8 oyster samples (12.5%) and 5 out of 13 mussel samples (38.5%) collected directly after importation in the Netherlands. RNA from samples associated with an outbreak of gastro-enteritis in the Netherlands in 2001 was re-analyzed using the NV primer sets. At least one identical sequence (142/142 nt) was found in three fecal and in two oyster samples related to this outbreak. Further surveillance of norovirus by detection and typing of viruses from patients with gastroenteritis and shellfish is warranted to clarify the causes of future outbreaks.

The genotypic diversity of Coxiella burnetii in clinical samples obtained from the Dutch Q fever outbreak episodes of 2007-2010 was determined by using a 6-locus variable-number tandem repeat analysis panel. The results are consistent with the introduction of one founder genotype that is gradually diversifying over time while spreading throughout The Netherlands.

No abstract

No abstract