Eurosurveillance - Volume 14, Issue 19, 14 May 2009

This issue of Eurosurveillance contains an article by a French team on the transmission of the new influenza A(H1N1) in Mexico, which uses published figures from the outbreak to estimate important parameters for transmission, among them the reproduction rate, R [1]. Such studies may have important implications for public health action in Europe.

An outbreak of infections with a new influenza A(H1N1) virus that was first detected in the United States and Mexico is currently ongoing worldwide. This report describes the initial epidemiological actions and outbreak investigation of the first 98 laboratory confirmed cases of infection with this new virus in Spain.

Following importations of cases from Mexico and the United States, by 11 May, United Kingdom surveillance activities had detected a total of 65 individuals with confirmed infections caused by the new influenza A(H1N1) virus. The infections were mainly in young people and younger adults and they spread within households and within schools. The illness in the United Kingdom is similar in severity to seasonal influenza and to date, besides one case of bacterial pneumonia, no clinically serious cases have occurred.

As of 12 May 2009, 5,251 cases of the new influenza A(H1N1) have been officially reported to the World Health Organization (WHO) from 30 countries, with most of the identified cases exported from Mexico where a local epidemic has been going on for the last two months. Sustained human-to-human transmission is necessary to trigger influenza pandemic and estimating the reproduction ratio (average number of secondary cases per primary case) is necessary for forecasting the spread of infection. We use two methods to estimate the reproduction ratio from the epidemic curve in Mexico using three plausible generation intervals (the time between primary and secondary case infection). As expected, the reproduction ratio estimates were highly sensitive to assumptions regarding the generation interval, which remains to be estimated for the current epidemic. Here, we suggest that the reproduction ratio was less than 2.2 - 3.1 in Mexico, depending on the generation interval. Monitoring and updating the reproduction ratio estimate as the epidemic spreads outside Mexico into different settings should remain a priority for assessing the situation and helping to plan public health interventions. .

The Netherlands is again facing a sharp increase in Q fever notifications, after the unprecedented outbreaks of 2007 and 2008. The most affected province of Noord Brabant has a high density of large dairy goat farms, and farms with abortion waves have been incriminated. Mandatory vaccination of small ruminants has started and should have an effect in 2010. A large multidisciplinary research portfolio is expected to generate better knowledge about transmission and additional control measures.

We report a case of anaphylaxis following meningococcal chemoprophylaxis of a healthcare worker, despite no history of direct contact with a patient who had meningococcal disease. The public health implications of this case are discussed.

Antibodies against hepatitis E virus (anti-HEV) were found in 248 Swedish and Danish patients between 1993 and 2007. Most patients were symptomatic and tested for anti-HEV due to travel abroad. Among patients with known country of infection, most were infected in Asia, mainly on the Indian subcontinent. However, 29 patients were infected in Europe, nine of these had HEV IgM and/or HEV RNA in serum. In sera from 65 of 141 tested patients HEV RNA could be detected, and 63 strains could be typed by limited sequencing within ORF2. HEV RNA was found in sera from 71% of the patients with HEV IgM and IgG and in 18% of the patients with only detectable HEV IgG. It was also found up to three weeks after the onset of disease in 67% of the patients with known date of onset. Patients infected in Europe were infected by genotype 3, and were older than those infected by genotype 1 (mean age 55.3 vs 30 years, p<0.001). Since it is known that genotype 3 can infect domestic pigs, HEV strains from 18 piglets in 17 herds in Sweden and Denmark were sequenced. Phylogenetic analyses of the genotype 3 strains showed geographical clades and high similarity between strains from patients and pigs from the same area. There are thus autochthonous hepatitis E cases in Scandinavia, and there are probably many undiagnosed ones. Patients with hepatitis of unknown etiology should therefore be investigated for anti-HEV even if they have not been outside Europe, since infections acquired from pigs or other animals should be taken into consideration.

In 2006, a new variant of Chlamydia trachomatis (nvCT) was reported in Sweden. The nvCT contains a deletion that includes the targets for the C. trachomatis genetic diagnostic single-target systems from Roche Diagnostics and Abbott Laboratories. Roche and Abbott have now developed certified dual-target assays that can detect the nvCT. This study examined the nucleic acid amplification tests (NAATs) currently used (in 2009) for C. trachomatis detection in laboratories from 17 European countries and five countries/regions outside Europe that are participating in the United Kingdom (UK) National External Quality Assessment Service (NEQAS). It further examined changes in these laboratories' testing strategy during the period from 2006 to 2009, and their performance regarding nvCT detection. A UK NEQAS blinded nvCT specimen was distributed to all 283 participating laboratories, which were asked to analyse the specimen according to their routine C. trachomatis diagnostic protocols for endocervical swabs. BD ProbeTec was the most commonly used NAAT, followed by Cobas Amplicor, Cobas TaqMan, and Aptima. From 2006 to 2009, the use of Cobas Amplicor, which does not detect the nvCT, decreased, but it was still used by 22% (n=57) of responding participants in 59% of the countries, 54 of these 57 used it as first assay. Virtually all of the other participants detected the nvCT correctly. Laboratories using commercial or in house NAATs that do not detect the nvCT are encouraged to carefully monitor their C. trachomatis incidence, participate in effective internal and external quality assurance and controls schemes, and to consider changing their testing system. .