News Release

Outbreak of tropical disease in nontropical area emphasizes need for preparedness and response

Peer-Reviewed Publication

The Lancet_DELETED

A chikungunya virus outbreak in Italy – a temperate country not usually affected by such viruses – emphasises the need for preparedness and response to emerging infectious threats as globalisation increases. These are the conclusions of authors of an Article published in this week’s edition of The Lancet.

Chikungunya virus (CHIKV) is an insect-borne virus transmitted to humans by the Aedes mosquitoes. Outbreaks have been reported in several African countries, the Indian subcontinent, and in southeast Asia. In recent years, a series of outbreaks have occurred in a large geographic area, covering Kenya, the Comoros Islands, La Réunion Island, other islands in the Indian Ocean, and India. During the outbreak on islands in the Indian Ocean, travellers from industrialised countries with a temperate climate became infected and were still infected on returning home. Symptoms of the CHIKV infection include joint pain and a fever of above 38.5 degrees Celsius.

Professor Antonio Cassone, Department of Infectious, Parasitic, and Immunomediated Diseases, Istituto Superiore di Sanità, Roma, Italy and colleagues investigated reports of large numbers of cases of febrile illness and arthralgia (showing signs of fever and joint pains) of unknown origin in two neighbouring villages in Ravenna, northeastern Italy. An active surveillance system was implemented, and blood samples were gathered and analysed to identify the cause. CHIKV was suspected early in the outbreak because one of the first patients to present symptoms was from a country affected by an outbreak of the virus, and the mosquitoes which carry the virus were present at high density in the area.

The researchers identified 205 cases of CHIKV between July 4 and September 27, 2007. They believed the cases originated from an Indian man who developed symptoms while visiting relatives in one of the villages, and was later shown to have developed antibodies against the virus. They also identified the virus in local samples of Aedes albopictus (also known as the tiger mosquito). Tests showed a high similarity between strains found in Italy and those identified during an earlier outbreak on islands in the Indian Ocean. The disease was fairly mild in nearly all cases, with only one reported death.

The authors conclude: “The occurrence of an outbreak of CHIKV infection in a country with a temperate climate emphasises that the predicted globalisation of human beings and vectors has become a reality. To promptly identify new potential threats that were previously restricted to tropical areas, clinical and diagnostic capacities have to be developed in countries with a temperate climate and in which vectors of exotic diseases already circulate.”

In an accompanying Comment, Dr Jean-Paul Chretien, Department of Defense Global Emergency Infections Surveillance and Response System, Silver Spring, MD, USA, and Dr Kenneth Linthicum, USDA-ARS Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL, USA, say that high income countries need to maintain their vector-control capabilities and “recognise that weaknesses in public-health systems in developing countries endanger all countries.” They say the recently implemented International Health Regulations, introduced by WHO in June and legally binding for WHO member states, provide a framework for tackling this, since they require countries to respond effectively to public-health emergencies that could spread internationally.

However, they conclude: “Without substantial financial and technical assistance, many developing countries would fail to meet these requirements. One positive note in the expansion of tropical infections to more temperate zones is that high-income countries may perceive them as shared risks, and provide additional resources to control them at their source.”

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Professor Antonio Cassone, Department of Infectious, Parasitic, and Immunomediated Diseases, Istituto Superiore di Sanità, Roma, Italy T) please complete telephone number E) cassone@iss.it

Dr Jean-Paul Chretien, Department of Defense Global Emergency Infections Surveillance and Response System, Silver Spring, MD, USA, please contact Debra Yourick T) +1 301-319-9471 E) Jean-paul.Chretien@NA.AMEDD.ARMY.MIL

The paper associated with this release can be found at http://multimedia.thelancet.com/pdf/press/Chikungunya.pdf


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