During the past two months, more than 150 suspected cases of chikungunya fever have occurred in the province of Ravenna, in north-east Italy, the European Centre for Disease Prevention and Control reports this week. Laboratory tests have confirmed that 27 individuals were definitely infected with the chikungunya virus, which is spread by Aedes mosquitoes.

The Italian authorities have countered by fumigating the village at the centre of the outbreak, Castiglione di Cervia. The ECDC advises travellers to the area, and people who have recently returned from the area, to take strict precautions against being bitten by mosquitoes. Pregnant women and people who are immunocompromised should consult their doctors before going to the region, it says.

Allegedly named from the phrase “that which bends up" in the African language Makonde, the chikungunya virus causes crippling joint pain, fever, and rashes, and can cause long-term problems, although it is rarely fatal. Originally identified in Tanzania and Uganda, these days the virus is better known in the Indian subcontinent and Indian Ocean islands, where several epidemics broke out in 2005. More than 1.25 million suspected cases were reported in India in 2006, with the attack rate reaching almost 45% in some areas. Sri Lanka, The Maldives, Malaysia, and Indonesia also reported outbreaks last year.

Although several European countries registered incidents in which tourists had imported the infection last year, so far the disease had not seemed to have spread within Europe. “If the local transmission is confirmed, it is the first time that chikungunya virus is known to be transmitted by mosquitoes within Europe,” a statement from the ECDC says.

Yet in January this year, Mike Service, of the Liverpool School of Tropical Medicine, warned that the disease could well emerge in Europe. One of Asian mosquito species that can carry the virus, Ae. albopictus, has become notorious following its introduction into many other regions, including the USA, Australia, several countries in Latin America, and 14 European countries, he explained in an article on ProMed Mail.

European countries with colder winters or anti-mosquito programmes have staved off the invasion. But the species has spread in some of the warmer Mediterranean countries, especially in Italy where it has dispersed to many regions and provinces.

“There must be the chance that in Europe an infected person returning from abroad (during the warmer months) could be bitten by Ae. albopictus which could then bite and infect another person,” he wrote.