§ Mr. Ron DaviesTo ask the Secretary of State for Health at what intervals the public health laboratory service central laboratory at Colindale collates regular reports of food contamination from regional laboratories.
§ Mr. Mellor[holding answer 19 July 1989]: Reports of contaminated food of public health significance are sent to the Communicable Diseases Surveillance Centre (CDSC) on a weekly basis. In the event of an unusual occurrence, PH LS headquarters and CDSC are immediately informed so that appropriate investigations can be instituted and advice given.
§ Mr. Ron DaviesTo ask the Secretary of State for Health how many incidents of listeria contamination in imported pate have been confirmed by the public health laboratory centre in England and Wales; and if he will list the circumstances under which samples were taken and the outlets involved, by county.
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§ Mr. Mellor[holding answer 19 July 1989]: The results of surveys of pate made by the PHLS, at present available, are that the PHLS Cardiff laboratory examined 73 samples of pate and 37 contained listeria. Of these, 59 samples were produced in Belgium and 32 were positive. In a continuing study in Cardiff further samples have been examined, and positive results obtained, from a variety of retail outlets. A larger national survey is currently in progress.
§ Mr. Ron DaviesTo ask the Secretary of State for Health if he will publish details of codes of practice under which the public health laboratory service conducts routine tests on samples submitted to it for analysis as suspected cases of food poisoning.
§ Mr. Mellor[holding answer 19 July 1989]: Each PHLS laboratory has its own procedures, adapted to local circumstances, based on the standard textbooks. In addition, the PHLS has a set of "Guidelines for the Microbiological Assessment of Foods".
§ Mr. Ron DaviesTo ask the Secretary of State for Health what his Department assesses to be a potentially inefective dose of listeria.
§ Mr. Mellor[holding answer 19 July 1989]: In a report "Foodborne Listeriosis" published in 1988, the World Health Organisation concluded that virtually nothing is known about the infectious dose of Listeria monocytogenes in man, nor is there good quantitative information relating to the amount of contaminated foodstuff ingested with the risk of acquiring the disease. It is likely that the infectious dose may be related to host susceptibility hence the early warning to vulnerable groups we issued on 12 July. With present knowledge and experience it is difficult to issue specific guidance on what constitutes a potentially infective dose of listeria.
§ Mr. Ron DaviesTo ask the Secretary of State for Health whether he will instruct the public health laboratory service to conduct tests for listeria during routine examination conducted by them on samples of food submitted by the public health service.
§ Mr. Mellor[holding answer 19 July 1989]: The type of tests carried out by the PHLS on samples of food taken during routine examination depend upon the type of food and the processing that it has received. It would not be appropriate to examine for listeria in every case. It is a matter for environmental health departments and the PHLS to decide upon the appropriate tests to be conducted according to the circumstances.