TROPICAL SPECIES HEADING NORTH AS CLIMATE WARMS

by Julio Godoy

(IPS) -- New species of insects have begun to establish themselves all across Europe, raising concerns about the impact of global warming on biodiversity and public health.

The school in Dorsten, a village near the German border with Belgium, had to be closed down recently because oak processionary caterpillars had infested the schoolyard, and teachers and parents were afraid of the health consequences for the students.

"The massive presence of these caterpillars in Germany is a very recent consequence of climate change," Stefanie Hahn, a biologist at the Federal Agency for Agriculture and Forestry, told IPS. "Because its presence is so recent, we have no systematic information on their evolution among us," Hahn stressed.

"These bugs can survive among us only when the weather is warm enough," Walter Maier, a physician specializing in the study of parasites at the University of Bonn, some 500 kilometres southwest of Berlin, told IPS.

For several years Europe has experienced warmer summers and winters, creating the conditions for the proliferation of insects and viruses normally considered foreign to the region.

The thaumetopoeidae is from a family of moths, which includes the oak processionary, so known because the moths march as in a procession. Its presence can provoke dermatitis, asthma, conjunctivitis, and other diseases in humans. Until recently, the thaumetopoeidae were almost never seen in northern Europe -- but last July, some villages in the German federal state of North Rhine-Westphalia were infested by the moths.

This year, thaumetopoeidae moths have also been seen in Belgium, in the Netherlands, and in London.

In the Belgian province of Limburg, the infestation during the summer was so strong that the local governor Steve Stevaert had to deploy the army to burn the caterpillars.

Something similar is happening with the phlebotominae, known commonly as the sand fly.

These flies, that feed on blood, are the primary vectors of leishmaniasis, or sand fly fever, a disease typical of the world's tropical areas.

Recently sand flies have been detected in Rheingraben, a 300-kilometre-long Swiss-German region along the Rhine River which streches from the city of Cologne, in Germany, to Basel, in Switzerland.

Last July, in Aachen, a city along the German border with Belgium, a boy bitten by a sand fly contracted leishmaniasis. The disease's primary symptoms are skin sores, but it can lead to damage of the spleen and liver, and provoke anemia, and even death.

"Sand flies survival in the Rheingraben region is a consequence of global warming," stressed Maier. "In such cases, which are become more and more frequent, sand flies and other vectors can become endemic among us," he warned.

Maier pointed out that the culicoides imicola, a very small midge, whose normal habitat is in sub-Saharan Africa, has migrated to Europe during the last few years, and has taken a liking to the new weather conditions in Germany.

This midge transmits several viral diseases, including African horse sickness, and bluetongue disease, also known as catarrhal fever -- affecting horses, sheep and, less frequently, cattle, goats, and even buffalo and deer.

"In the last months we have found more than 2,000 farms in Holland, Belgium, France, Luxembourg, and Germany, in which the blue tongue disease has been detected," Maier told IPS. "In Germany alone we counted up to 900 farms with infections," he said.

Maier said that in Germany, the virus is transmitted by local midge species. "The original vector was most likely imported with African animals into Europe," he said. "But given the warm summers and winters, there is the risk that it becomes endemic in Germany, and that we shall see in the coming years new epidemics of blue tongue disease among cattle and other breeding species. A similar thing can happen with the rift-valley virus and other disease vectors," he added.

Among the diseases that have become more frequent in Germany due to global warming, Maier mentioned borreliosis, the tick-borne meningoencephalitis, among other forms of encephalitis, some of Japanese origin.

Borreliosis, or Lyme disease, is an infectious disease transmitted by the bite of an infected tick of the borrelia garinni family, and the tick-borne meningoencephalitis, a viral inflammation of the brain and spinal cord and their meninges -- also transmitted by ticks.

The Japanese encephalitis is transmitted by midges infected with the West Nile virus. It mainly infects birds, but can also infect humans, and numerous animals, from horses and dogs, to squirrels and domestic rabbits.

"We believe that the number of ticks has grown dramatically in Germany in the last couple of years," Maier said. "It is the same with exotic midges, which have migrated from the Mediterranean region towards Northern Europe, to become endemic in these areas."

Maier indicated that the number of cases of borreliosis in Germany has risen in recent months. As for tick-borne meningoencephalitis, he said that cases of the disease have been identified as far north in Europe as in Norway and other Scandinavian countries.

"This is new," Maier stressed.

Given that all these phenomena are relatively recent, no thorough investigation has been carried out on the causal connections between climate change, the immigration and proliferation of exotic species in northern latitudes, and the growing incidence of rare diseases.

"The correlation between the all these variables, between growing numbers of ticks, vectors, and diseases is still unclear," Maier explained. "We have not had the time to carry out a real study on the presence of exotic arthropod and new transmittable diseases in Germany," he added.