Eurosurveillance - Volume 13, Issue 37, 11 September 2008

Two severe familial cases of botulism were reported to the health authorities in Brittany, north-west France, on 11 August 2008. An investigation was undertaken to identify additional cases, the vehicle of transmission, and to put in place adapted control measures.

The incidence of giardiasis in Central Lancashire increased following the introduction of a sensitive enzyme immunoassay diagnostic test in November 2002. We compared the epidemiological trends for 1996-2006 in Central Lancashire with a control area which used a standard wet preparation diagnostic method throughout. Poisson regression modelling was used to investigate trends in giardiasis before and after the introduction of the test. In the control area, incidence of giardiasis was four per 100,000 in 2005. In contrast, in Central Lancashire, the rates increased in temporal association with the introduction of the enzyme immunoassay test from 10.1 per 100,000 population in 2002 to 33.6 per 100,000 in 2006. The increase in giardiasis was unexplained by local factors including travel, outbreaks or sampling trends. The increase in giardiasis occurred in all age groups except for males aged 0-14 years and was most marked in males aged 25-44 years. The relative risk for trend post-test introduction in Central Lancashire was 1.11 (95% CI, 1.01-1.23). This suggests that the increase in giardiasis following the introduction of the sensitive enzyme immunoassay test was at least in part due to improved detection. There appears to be considerable under-diagnosis of giardiasis, particularly in adults. Additional research is required to evaluate the enzyme immunoassay test more widely. The test may assist in standardisation of diagnostic methods for giardiasis and enable more accurate estimation of disease burden and transmission routes.

Salmonella serovar Stanley is rare in Europe. In Switzerland, the number of reported isolates has increased from 2 in 2000 to 25 in 2005. A nationwide outbreak of gastrointestinal illness due to S. Stanley occurred from September 2006 through February 2007. Eighty-two cases were documented. Males were 56%; mean age of the cases was 45.7 years (range 0-92). Forty-seven cases (57%) occurred in three western cantons: Vaud, Bern, and Geneva. Twenty-three cases (28%) were hospitalised. In the case-control study conducted to find the source of the outbreak, cases were more likely than controls to have eaten local soft cheese (OR 11.4, p=0.008). One clone of S. Stanley strain was isolated from soft cheese and from 77 cases (94%) who reported no history of having travelled abroad. The outbreak ended after the withdrawal of the cheese from the market. This is the first S. Stanley outbreak in Switzerland and the first in Europe unrelated to imported products, suggesting an increased local circulation of this previously rare serotype.

As the number of detected cases may be closely related to the intensity of the search and the methods and criteria used in the diagnosis, we believe that exhaustive surveillance under pressure from the media could lead to over-diagnosis and unnecessary treatments which, like that of pregnant women, are not free of risk.