Eurosurveillance - Volume 19, Issue 13, 03 April 2014

On 18 November 2013, five residents of Saint Martin presented with severe joint pain after an acute episode of dengue-like fever. Epidemiological, laboratory and entomological investigations provided evidence of the first autochthonous transmission of chikungunya virus in the Americas. The event indicates a risk of epidemics in America and Europe through substantial passenger traffic to and from continental France. We describe detection and confirmation of the first six cases and results of the first weeks of surveillance.

Since 5 December 2013, chikungunya virus (CHIKV) has been demonstrated to circulate in the Caribbean, particularly on Saint Martin. This region is facing a concomitant dengue virus (DENV) outbreak. Of 1,502 suspected chikungunya cases, 38% were confirmed chikungunya and 4% confirmed dengue cases, with three circulating serotypes. We report in addition 2.8% CHIKV and DENV co-infections. This study highlights the importance of the case definition for clinicians to efficiently discriminate between DENV infection and CHIKV infection.

A Zika virus (ZIKAV) outbreak started in October 2013 in French Polynesia, South Pacific. We describe here the clinical and laboratory features of two mothers and their newborns who had ZIKAV infection as confirmed by ZIKAV RT-PCR performed on serum collected within four days post-delivery in date. The infants' infection most probably occurred by transplacental transmission or during delivery. Attention should be paid to ZIKAV-infected pregnant women and their newborns, as data on the impact on them are limited. .

On 6 December 2013, two laboratory-confirmed cases of chikungunya without a travel history were reported on the French part of the Caribbean island of Saint Martin, indicating the start of the first documented outbreak of chikungunya in the Americas. Since this report, the virus spread to several Caribbean islands and French Guiana, and between 6 December 2013 and 27 March 2014 more than 17,000 suspected and confirmed cases have been reported. Further spread and establishment of the disease in the Americas is likely, given the high number of people travelling between the affected and non-affected areas and the widespread occurrence of efficient vectors. Also, the likelihood of the introduction of the virus into Europe from the Americas and subsequent transmission should be considered especially in the context of the next mosquito season in Europe. Clinicians should be aware that, besides dengue, chikungunya should be carefully considered among travellers currently returning from the Caribbean region.

In 2010, the first outbreak of West Nile virus (WNV) infection in Greece was recorded, the largest in Europe since 1996. After 2010, outbreaks continued to occur in different areas of the country. Enhanced surveillance was implemented during transmission periods (June to October). We investigated the 2012 outbreak to determine its extent and identify risk factors for severe disease using regression models. Of 161 cases recorded in 2012, 109 had neuroinvasive disease (WNND). Two outbreak epicentres were identified: the southern suburbs of Athens in July and a rural area in East Macedonia &Thrace in August-September. The case fatality rate of the WNND cases was 17% (18/109). A lower case fatality rate was recorded in the two epicentres (7% (2/28) and 9% (4/46)): the higher case fatality outside the two epicentres might reflect a diagnostic bias. Age above 74 years (adjusted risk ratio (RR): 7.0; 95% CI: 2.2-22) and chronic renal failure (adjusted RR: 4.5; 95% CI: 2.7-7.5) were independently associated with WNND-related death. In three PCR-positive samples, sequencing revealed WNV lineage 2 identical to the 2010 strain. The occurrence of human cases in three consecutive years suggests that WNV lineage 2 has become established in Greece. Raising awareness among physicians and susceptible populations (elderly people and persons with co-morbidities) throughout Greece is critical to reduce the disease impact. .

We provide an update on the epidemiology and disease characteristics of tick-borne encephalitis (TBE) in Switzerland. Data were collected through the mandatory notification system of the Federal Office of Public Health. Between 2005 and 2011, a total of 1,055 TBE cases were reported, with a peak of 244 cases in 2006. The average yearly incidence was 2.0/100,000 inhabitants nationwide, with the highest regional value (7.8/100,000) in eastern Switzerland. Incidence by age peaked in 60-69 year-old patients, males predominated in all age groups. Most patients suffered from meningoencephalitis (n=567) or meningitis (n=246), seven of 1,055 patients (0.7%) died. Of 617 patients who were 40 years and older, 442 (72%) suffered from a severe course of illness, compared to 196 (51%) of 384 patients younger than 40 years. Most patients were not immunised against TBE, and in 33 of 1,055 patients (3%), vaccine failure was found possible. Ongoing surveillance of TBE and intensified efforts in promoting TBE vaccination for the population at risk will be needed in light of its considerable morbidity. .