West Nile infections raise preparedness concerns in Europe

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Aug 27, 2010 (CIDRAP News) – A West Nile virus (WNV) seroprevalence study of Italian organ donors revealed that 1.2% of 1,248 serum samples were positive and that some of the donors who had been exposed to the virus were from regions where infection wasn't thought to be a risk.

The researchers, who reported their findings yesterday in Eurosurveillance, said their findings were unexpected and that gaps in mosquito and disease surveillance systems could have masked a broader reach of WNV. Their data raise concerns about the risk of WNV transmission to organ recipients, and the finding of antibodies in those from low-risk areas illuminates concern about a wider scope of the disease.

The first human cases of WNV infection surfaced in Italy in September 2008, and by the following summer infections were thought to be limited to just four provinces, Bologna, Ferrara, Modeno, and Reggio-Emilia, according to the report.

Based on those findings, health officials issued WNV screening guidance that focused on donors from those areas. A case of WNV transmission to a liver donation recipient shortly before the guidelines went into effect prompted health officials to seek a nationwide survey of WNV prevalence.

Their review found antibody responses in donors from Piedmont, Friuli-Venezia Giulia, Marche, and Basilicata regions, which surprised the researchers and suggested that WNV infections are occurring in several areas of Italy.

Italy needs a more accurate nationwide approach to transplantation risk assessment, as well as better illness and mosquito surveillance, the group concluded.

In another report in the same issue of Eurosurveillance, researchers reported the first human WNV infections in Greece. The cases were identified this summer between early July and the middle of August. Researchers identified 99 cases, 81 of them with neuroinvasive WNV in the Central Macedonia region of northern Greece. They occurred mainly in patients age 50 and older; the median age was 70.

The authors suggested that increased rainfall, high temperatures, and high humidity this summer in some parts of the Central Macedonia region might have contributed to a greater number of Culex mosquitoes.

Based on the identification of the WNV cluster, Greek officials have released guidelines for health professionals, established a surveillance system, and educated the public about disease prevention. Blood donation screening guidelines have also been revised, and authorities have beefed up mosquito-control programs.

In a related editorial that appears in the same Eurosurveillance issue, authors from the European Centre for Disease Prevention and Control (ECDC) said the emergence of WNV cases in Greece serves as a reminder that the virus is a reemerging pathogen in Europe. They wrote that the events show the need for stronger surveillance systems and response plans.

Public health officials need a better picture of WNV risk area in Europe and neighboring areas so they can launch control measures, especially guidelines for blood donation and organ transplants, the editorial said.

See also:

Aug 26 Eurosurveillance report on WNV in Italian solid organ donors

Aug 26 Eurosurveillance report on first WNV infections in Greece

Aug 26 Eurosurveillance editorial on WNV preparedness in Europe

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