The risk of Chikungunya and Dengue outside of the tropics: can mosquito traps help reduce the risk?

Chikungunya fever and Dengue fever have long been a problem of the tropics and subtropics. The more temperate regions of the world were considered safe and without risk, but this has changed.

 

A mosquito capable of transmitting Dengue and Chikungunya has been spreading into many regions of the world: large parts of Europe and the Americas are now infested by the Asian tiger mosquito (called Aedes albopictus by scientists). International trade and travel, the species' remarkable adaptation to the urban environment, and a combination of global warming and the acclimatization to cooler climates are paving the way for a continuous spread of the Asian tiger mosquito.

The risk for an outbreak of the Chikungunya virus or the Dengue virus in a specific area depends on two factors:

1. Risk of the presence of a person who is infected with the Chikungunya virus or Dengue virus.
2. Risk of transmission of the respective virus by insect disease vectors such as the Asian tiger mosquito (Aedes albopictus). The larger the tiger mosquito population, the larger the risk.
   

Hitchhiking Chikungunya

A recent incident where these two risk factors came together was in the Emiglia-Romana region in Northern Italy; however, Italy was not unprepared. As a reaction to the Chikungunya virus epidemic on the French island of La Réunion in the Indian Ocean at the beginning of 2006, the Italian Health Ministry had set up a special surveillance program for Chikungunya cases in August of the same year.
 
Despite these precautions, a Chikungunya virus outbreak occurred in the areas of Ravenna, Forlì-Cesena, Rimini and Bologna in the Emiglia-Romana region in the summer of 2007. As predicted, the vector was the Asian tiger mosquito. At least 200 people were infected with the virus. Luckily, the outbreak could be contained and the virus did not manage to survive into the tiger mosquito season of 2008.

Infected people carrying Dengue or Chikungunya viruses into new areas of the world is not so unusual. This first risk factor is actually increasing due to growing international tourism and the rising number of travelers to countries in Asia and Africa where the Chikungunya virus or the Dengue virus is already present and spreading.

For example, the authorities of the Emiglia-Romana region in Italy have reported that the first case of the Dengue virus being imported into the Emiglia-Romana region dates back to the year 2000; a further case was reported in 2005. Then, four cases were recorded in 2006, and six in 2007.

For the Chikungunya virus, the first two known cases being imported into the Emiglia-Romana region were reported in 2006. One came from Mauritius, the other from India. Three further Chikungunya cases were recorded in 2007, this time all of them coming from India. The first of these was the source of the Chikungunya outbreak in the areas of Ravenna, Forlì-Cesena, Rimini and Bologna.

Containing Asian tiger mosquitoes and the risk they carry

The second risk factor, i.e. the risk of virus transmission by vectors such as the Asian tiger mosquito, is surging due to its continued spreading into new regions. A prime example is the infestation of Italy by the tiger mosquito. Introduced in 1990/1991, the mosquito was present in parts of northern Italy and some areas in central Italy by 1997 and has now colonized most of the country.

Given these two risk factors, any strategy wanting to contain the risk of Chikungunya or Dengue fever must rely on two main pillars:

1. Asian tiger mosquito control and entomological surveillance that pursues the objective of reducing the tiger mosquito population density as much as possible. To achieve this objective an arsenal of different actions need to be taken against the tiger mosquito.
2. Early detection of suspect cases and immediate implementation of control measures aimed at preventing any virus transmission from an individual to tiger mosquitoes and from tiger mosquitoes to another individual.

Over 15 years Biogents AG , a spin-off of the University of Regensburg, Germany has developed and fine-tuned a trap that specifically targets the tiger mosquito. This tiger mosquito trap has now been introduced into the consumer market under the brand name "Biogents Mosquitaire".

The efficacy of the Biogents tiger mosquito trap has been proven in numerous international studies, also showing that it is superior to any other trap against tiger mosquitoes.  For references, see our list of scientific publications on the efficacy of the Biogents trap for tiger mosquitoes .

Testing Biogents tiger mosquito traps for the suppression of mosquito populations and Dengue transmission

In Italy, scientific field studies are beginning to indicate the ability of Biogents tiger mosquito traps to reduce the tiger mosquito population. The results of these field studies will be published over the next couple of months and will also be available on this site.

An additional aspect of the new tiger mosquito trap is being studied in Manaus in the Brazilian State of Amazonas, in a major field study that is supported by the World Bank, the Bill and Melinda Gates Foundation and the State of Amazonas. Here, the Biogents Mosquito Research Group, together with Brazilian universities and public health authorities, have begun to study the application of the Biogents tiger mosquito trap not only for the suppression of the tiger mosquito population, but also in cutting the transmission of the dengue virus.

All this will make the Biogents Mosquitaire tiger mosquito trap an interesting tool for the regional and local authorities in Italy and beyond to consider for their fight against the tiger mosquito in an integrated approach. The Biogents Mosquitaire tiger mosquito trap should prove to be a valuable addition to their arsenal of tiger mosquito control instruments.