Usutu Virus Highlights Importance of Disease Surveillance Primary tabs

Feb 14, 2013 | Katharina Schwan | Outbreak News

In 2001, the city of Vienna, Austria noticed a strange and sudden disappearance of its Eurasion Blackbird population. Researchers and scientists were equally puzzled by the decrease in blackbirds and set out to find a reason. The cause was soon discovered. A new virus previously only isolated in mosquitoes in tropical and subtropical Africa had somehow migrated to Europe and infected local bird species, which were susceptible to the foreign virus. Usutu virus (USUV) had never before been associated with severe illness or fatalities in humans or animals.

At the time of the discovery, it was believed that this was the first time USUV struck in Europe. However, the latest findings from the University of Veterinary Medicine, Vienna (Vetmeduni Vienna) suggest otherwise. In 1996, blackbirds in Tuscany began dying off in large numbers. The causative agent was never discovered. Now, seventeen years later, an analysis of stored tissue samples from the dead birds identified the same USUV strain that caused the Viennese avian die-off as the culprit.

While USUV does not pose a major threat to humans, the five-year lag time between the first outbreak in Italy and the discovery of the virus in Austria illustrates an important gap in surveillance work. 

It is well established that changes in climate, environmental mismanagement, and an increase in travel and trade has given emergent diseases the push needed to make themselves known. Unfortunately, as seen with the recently discovered coronavirus, it is not until a human or two falls severely ill that governments and the public take notice.

Once a new virus or bacteria is discovered, public health authorities, scientists, researchers, and the media are all on high alert. Since nothing is known about this newest threat, the usual reaction is fear. Until more is known about the pathogen’s characteristics, such as its virulence and its ability to spread effectively from animal to human and between humans, the worst is expected.

While governments are becoming more effective and timely in responding to emerging public health threats, surveillance work should emphasize the identification of new pathogens before they cause harm. As an example, the PREDICT project, on which HealthMap collaborates, seeks to detect novel zoonotic diseases with pandemic potential early to prevent emergence and spread. As part of PREDICT, the Global Animal Information System (GAINS) is involved in essential surveillance field work. This includes actually trapping wildlife and taking blood samples to analyze viruses that exist in nature. Unfortunately, this type of basic surveillance is usually poorly funded since the impact on human health is not acutely obvious. Nevertheless, this work is imperative to literally stop emerging diseases in their tracks and to effectively monitor and manage pathogens before they become a problem.

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