Epidemiological update: Possible local transmission of dengue virus in Greece, 6 September 2012Archived

Epidemiological update

On 3 August 2012, a probable case of dengue infection was reported in a resident in west Greece (Agrinio). The 84 year old patient, who had severe underlying conditions and septicaemia, died on 30 August 2012.

On 3 August 2012, a probable case of dengue infection was reported in a resident in west Greece (Agrinio). The 84 year old patient, who had severe underlying conditions and septicaemia, died on 30 August 2012. He had not travelled abroad to a dengue transmission risk area. The case has been classified as a probable dengue case due to the presence of a high titer of IgM dengue antibodies in a serum sample. In addition, dengue NS1 antigen was detected in serum with PCR but dengue nucleic acid tests were negative. 

Dengue is a mosquito-borne disease caused by any one of the four types of dengue virus.  Most infections occur in tropical regions with an estimated 50 to 100 million infections annually in 125 countries. There is no direct person-to-person transmission. The main vector of dengue worldwide, the Aedes aegypti mosquito, is not present in Greece.  Aedes albopictus, an effective secondary mosquito vector known to cause outbreaks, has been present in western Greece since at least 2003. There is currently no information about its presence in the local area where the case lived.

Dengue infections are rare in Europe and most cases are imported as a result of infection in tropical areas. Local transmission of dengue virus is extremely rare in Europe. The last recorded local transmission of dengue virus in Greece was during an outbreak in 1927 – 1928 involving the Aedes aegypti mosquito. Autochthonous cases were reported by France and Croatia in 2010.

The Hellenic Centre for Disease Control (KEELPNO) has initiated epidemiological and entomological investigations which are likely to produce critical information for assessing the risk of local transmission of dengue. The investigations include active retrospective and prospective case finding, review of compatible cases, and a survey of people living within a 200 m radius of the case. Clinicians and public health professionals in the area are being informed about the clinical presentation of dengue and the possibility of local transmission. Public awareness campaigns about personal mosquito protection are already ongoing as a result of West Nile virus transmission.

Although it may never be fully established to what extent dengue contributed to the patient’s death, the laboratory test results clearly indicate an acute dengue virus infection. Introduction of dengue virus via infected travellers with subsequent local transmission is possible as demonstrated by the reports of local transmission in France and Croatia. The entomological investigation will provide further evidence of the presence of the Aedes albopictus mosquito in the area. Epidemiological investigations and serological surveys will provide information on whether dengue virus is circulating in the local population.