Schmallenberg virus metabolic mosquitoes discovered

Belgian scientists have discovered the carrier of the Schmallenberg virus

17/03/2012

For some time now, the Schmallenberg virus has raged in many European countries. The viral disease is responsible for a variety of stillbirths in cattle, sheep and goats. The calves or lambs of the diseased animals are often born with severe malformations so that they are not viable in a row. Belgian researchers have now been able to identify the transmitter. These are several types of mosquitoes, some of which were already responsible for transmission of other viral diseases.

Schmallenberg pathogen is being prepared throughout Europe
Since its discovery, almost 1,000 farms in Germany have been affected by the viral infectious disease. The recently unknown Schmallenberg pathogen is responsible for a high number of stillbirths among sheep, goats and cattle herds. The born kittens of the infected dams are either already dead or with serious malformations to the world. In addition to the Federal Republic of Germany, agricultural holdings in countries such as Belgium, France, Great Britain or Holland are also affected by the epidemic. So far, a spreading to humans was not observed, however, the viruses were discovered only in the year 2011, so that a final evaluation of the Schmallenberg virus did not yet take place.

Mosquitoes responsible for transmission
Scientists at the Belgian Institute of Tropical Medicine (IT) in Antwerp say it has managed to locate the exact vectors. These are special mosquito species that have been responsible for the transmission of infectious animal diseases. „Studies have shown that the mosquitoes Cimicoides obsoletus, C. dewulfi and C. Pulicaris transmit the Schmallenberg virus.“ Three of the five identified lunatid species had established the bluetongue transmission pathway, the research team reports. For several months, although veterinarians and researchers suspected that the only 100 nanometers Schmallenberg virus is transmitted by insect bites, it remained unclear until the discovery of which specific mosquitoes are responsible.

Adult mothers recover quickly
The immune system of the infected farm animals is powerless against the invaders. While the mothers phase by phase fever, milk decline, loss of appetite and sometimes underweight and thus show only short-term disease symptoms, stabilizes the state of health within a relatively short period of time. The worrying sequelae, according to the experts, are the miscarriages and stillbirths. In November 2011, the disease near the village of Schmallenberg was discovered for the first time by experts from the Friedrich-Löffler-Institute for Animal Health in Cattle. The viruses showed clear parallels to the Akabane infection, which also affects mammals by means of mosquitoes and causes similar signs of complaint. The researchers assigned the pathogen to the orthobunyavirus. Shortly before this, animals in Dutch cattle herds showed similar symptoms, although it is still unknown whether the viral disease was already circulating or newly registered at that time.

Declining rate of new infections expected
Experts from the European Food Safety Agency EFSA believe that the rate of new infections will decline in the near future. In the following months, however, the number of malformations caused by the Schmallenberg virus will initially continue to increase. Additional measures are not necessary in the opinion of the EU Commission. The viral infection is treated the same as other pathogens in the veterinary sector as well. (Sb)

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