D. Mueller-Doblies

Distribution of Cryptosporidium species in sheep in the UK

There have been few studies of the distribution of Cryptosporidium species and genotypes in sheep, and the anthropozoonotic potential has been questioned since one of the major human pathogens, Cryptosporidium parvum, is not always found. To investigate the situation in the UK we undertook three studies: a reactive sampling programme of flocks identified as exposures for human cases of cryptosporidiosis; investigation of neonatal cryptosporidiosis in lambs; and a screening programme of lambs at an open farm. C. parvum was the only species found in neonatal lambs with cryptosporidiosis and predominated in flocks sampled reactively to a human case of cryptosporidiosis. C. bovis was also found in the latter study but at a lower frequency than C. parvum. C. bovis and the cervine genotype were found in the orphan lambs under the screening programme. The results of these studies show that C. parvum is important in neonatal lamb diarrhoea and is widespread in sheep flocks in the UK, but that other Cryptosporidium species and genotypes are also present. Sheep, and young lambs in particular, must still be considered as a source of C. parvum infection for humans.

Cryptosporidium hominis in a goat and a sheep in the UK.

IN THE UK, human diarrhoeal disease associated with the protozoan parasite Cryptosporidium is caused mainly by Cryptosporidium parvum and Cryptosporidium hominis , which together account for 96 per cent of cases, in approximately equal proportions ([Nichols and others 2006][1]). C parvum is

Investigation of farms linked to human patients with cryptosporidiosis in England and Wales.

The study investigates farms suspected of being sources of zoonotic human cryptosporidiosis. A variety of implicated farm animal species were sampled and tested to detect Cryptosporidium oocysts and investigate genetic linkage with human patients. Risk factor information was collected from each farm and analysed by multivariable logistic regression to detect significant associations between factors and Cryptosporidium in animals. The results showed that average sample prevalence of Cryptosporidium infection was highest in cattle, sheep and pigs ( approximately 40-50%), in the mid-range in goats and horses (20-25%) and lowest in rabbits/guinea pigs, chickens and other birds ( approximately 4-7%). A single sample from a farm dog was also positive. Cryptosporidium parvum, which has zoonotic potential, was the commonest species and was most likely to be present in cattle and, to a lesser extent, in sheep. In particular, young calves and lambs shed C. parvum and this finding was corroborated in a statistical model which demonstrated that samples from groups of preweaned animals were 11 times, and immature animal groups six times, more likely to be positive than groups of adult animals, and that samples from a farm with a cattle enterprise were twice as likely to be positive than farms without a cattle enterprise. On seven out of eight farms, at least one C. parvum isolate from an animal sample was indistinguishable at the gp60 locus from those found in the human patients, indicating that farm animals are a likely source of infection for humans.

Investigation of the role of companion animals in the zoonotic transmission of cryptosporidiosis.

Companion animals owned by human patients with cryptosporidiosis (cases) and those animals owned by the wider human population (controls), were studied to determine whether Cryptosporidium was more likely to be excreted by case animals than controls. A total of 280 recently voided faecal samples (114 case animals and 166 control animals) were collected and tested by immunomagnetic separation and immunofluorescent microscopy. A multivariable model was also created to identify pet characteristics, contacts and management factors associated with Cryptosporidium infection in animals, using information collected by a standardized questionnaire. The model was designed to take into account the clustering of samples at the owner level and whether the sampled animal was a case or control.

A comparison of the efficacy of different disinfection methods in eliminating Salmonella contamination from turkey houses

Aims:  This study aimed to compare the efficacy of different disinfection methods in eliminating Salmonella contamination from turkey houses.

The estimation of pooled-sample sensitivity for detection of Salmonella in turkey flocks.

Aims:  To investigate the effectiveness of pooled sampling methods for detection of Salmonella in turkey flocks.

Cryptosporidium species in lambs submitted for diagnostic postmortem examination in England and Wales

CRYPTOSPORIDIOSIS is a common enteric disease in human beings and a wide range of animal species. Cryptosporidium parvum is the main species responsible for zoonotic infection in Britain. In a previous study, [Pritchard and others (2007)][1] evaluated the zoonotic hazard associated with subclinical

Comparison of sampling methods to detect Salmonella infection of turkey flocks.

Aims:  To compare the efficiency of various sampling methods for detection of Salmonella in turkey flocks.

A retrospective analysis of Salmonella serovars isolated from pigs in Great Britain between 1994 and 2010

A retrospective study analysing Salmonella serovars and antimicrobial resistance data from pigs in Great Britain between 1994 and 2010 was performed. Data were obtained through scanning surveillance and compared with prevalence data from other livestock species as well as human data. During the study period, two serovars, S. Typhimurium and S. Derby, predominated in British pigs. The total number of Salmonella incidents has decreased steadily over the study period, from 360 incidents per year in 1994 to 172 incidents in 2010. S. Typhimurium has been the most common serovar every year, but the relative percentage went down over the past few years. During the same time period, monophasic strains of S. Typhimurium have increased in numbers and were accounting for as much as 25% of incidents in 2010, representing the second most common serovar in British pigs in 2010. Antimicrobial resistance data from S. Typhimurium isolates show that the percentage of isolates which are resistant to six or more antimicrobials has increased from 27.2% in 1994 to 58.3% in 2010 and that the percentage of isolates fully sensitive to the panel of antimicrobials tested was only 3.3% in 2010. S. Typhimurium isolates belonged mainly to phagetypes DT193 and U288 in 2010, and an increase can be seen in the number of isolates belonging to phage type DT193. DT104, which was the predominant phagetype during the 1990s, has gone down considerably and represented less than 5% of all S. Typhimurium isolates in 2010. Monophasic strains of S. Typhimurium belonged mainly to phagetype 193 with less than 20% belonging to phagetype 120. The overall trend shows that the number of Salmonella incidents reported from British pigs has gone down considerably over the 17-year study period, but that the relative percentage of monophasic strains of S. Typhimurium has increased significantly. This trend seems to be in line with observations from other European countries, where an increase of this serovar can be seen both in livestock and in human patients. The increasing percentage of Salmonella-isolates which show multi-resistance is a matter of concern and has to be monitored carefully in order to assess any potential risks this may pose to human patients.

Investigations of the Distribution and Persistence of Salmonella and Ciprofloxacin‐Resistant Escherichia coli in Turkey Hatcheries in the UK

This study aimed at gaining information on the presence of Salmonella in UK turkey hatcheries and possible epidemiological links between breeding farms, hatcheries and finishing farms. The presence of ciprofloxacin‐resistant E. coli in hatchery samples, as well as in faecal samples from farms, and trends in occurrence of resistance were also investigated. Over a 2 year‐period, four British turkey hatcheries were visited and intensively sampled for the presence of Salmonella and ciprofloxacin‐resistant E. coli. In two hatcheries, a link could be demonstrated between the presence of certain Salmonella serovars in the hatcheries and on breeding and finishing farms. Within the hatcheries, serovars linked to breeding farms were found more frequently in the poult processing and dispatch areas, whereas serovars identified as ‘resident hatchery contaminants’ were predominantly found inside the hatcher cabinets. Ciprofloxacin‐resistant isolates of S. Senftenberg were identified in one hatchery, which coincided with enrofloxacin treatment of some of the breeding flocks. Ciprofloxacin‐resistant E. coli was found in two hatcheries, and the majority of these isolates showed multidrug resistance.