Bacteria use against deadly dengue viruses

Tropical Disease: Curious weapon against dengue fever

05/04/2014

Worldwide, billions of people in over 100 countries are threatened by dengue viruses. There is no vaccine protection against the potentially fatal dengue fever. Therefore, researchers now resort to a strange weapon. They want to fight the tropical disease with the help of bacteria.

So far there is no vaccine protection against dengue fever
According to the World Health Organization (WHO), around 2.5 billion people worldwide are threatened by dengue viruses. It is estimated that around 390 million people will become infected with the virus every year. There is no vaccine protection against the potentially deadly tropical disease. Nor does a causal therapy. Researchers now want to fight dengue fever with the help of bacteria. Mosquito populations should be specifically infected with Wolbachia microbes. Tests would already run on different continents.

Green technology a little different
Most people imagine a green technology differently. Only a few would think of the targeted infection of whole insect populations with bacteria. But this is exactly what is being tried in Asia, Australia and America. In the future, in many places only yellow fever mosquitoes (Aedes aegypti) can be active, carrying the bacterium Wolbachia in the body. These mosquitoes usually transmit several diseases, from yellow fever to chikungunya to dengue fever. Wolbachia bacteria can drastically reduce the spread of many pathogens in insects for largely unknown reasons. In addition, the microbes, which colonize only invertebrates, have a reproductive knot that allows them to take over entire host populations. Therefore, there is hope that this combination could curb the spread of dengue viruses naturally, without any chemicals.

40 percent of the earth's inhabitants live in risk areas
Numerous scientists have been denouncing dengue fever for years. The disease, which causes flu-like symptoms such as fever, joint and limb pain and can sometimes be fatal, is spreading rapidly around the world. According to studies, about 40 percent of the world's inhabitants live in a risk area. The virus does not stop at the US or Europe either. In 2010, isolated transmissions were reported in Croatia and southern France, and in the autumn of 2012 a major outbreak followed on the Portuguese island of Madeira. The host country of the upcoming FIFA World Cup, Brazil, is also among the risk areas. Half a million international fans are expected to attend the tournament from the beginning of June, including tens of thousands from Germany.

Insecticides bring no success and harm the environment
One measure used in many countries is the spraying of insecticides against the mosquitoes. But the desired success still remains. In addition, this method damages the environment. Therefore, many experts are looking for new approaches hopes for the bacterium Wolbachia pipientis, which live in the cells of their hosts. The already discovered in the 1920s, microorganisms colonize a variety of invertebrate animals worldwide, such as roundworms and spiders, but especially insects. Experts estimate that up to two-thirds of all insect species carry the bacteria in their bodies, even though not all populations of these different species are affected.

Plans criticized in Brazil
A few years ago, plans to stem Dengue fever in Brazil caused quite a stir. There, genetically modified mosquitoes should contain the population of the mosquito Aedes aegypti. Thus, by keeping unchanged female mosquitoes mating with the genetically modified specimens, the common offspring should die already in the larval stage. Since nobody knows what consequences threaten the ecosystem, if the mosquito Aedes aegypti is exterminated, critics worried very early on above all about the ecological consequences. For example, the mosquito is the food source of many birds and other animals. It may even be possible to promote the spread of dengue fever if the mosquitoes develop resistance so that the offspring of the genetically modified animals survive. (Ad)