New parasite discovered in mosquitoes

Hamburg scientists detect parasites for the first time in Germany

09/07/2013

Scientists from Hamburg have for the first time in Germany larvae of the so-called „Dog skin worm“ found in mosquitoes. Infections with these had so far been only in Southern Europe, Africa and Asia, but the „Climate change and the import of infected dogs from southern Europe may be the reasons for the establishment of this parasite, which was previously not native to Central Europe“, such a current press release of the Bernhard Nocht Institute (BNI) for tropical medicine in Hamburg.

Dog Worm not yet established in Central Europe
Scientists of the Bernhard Nocht Institute for Tropical Medicine (BNI) have for the first time in Germany larvae of the so-called „Dog skin worm“ (Dirofilaria repens) found in mosquitoes - this had not yet occurred in Central Europe. The larvae are anything but harmless, because as the BNI writes, the mosquitoes could in rare cases „transmit the infection to humans and cause about a meningitis“ - So far, however, no infections are known in Germany.

Interdisciplinary research team investigates around 75,000 mosquitoes
In the run-up to the discovery of the dog-skin worm, an interdisciplinary research team led by Professor Egbert Tannich, head of the Department of Molecular Parasitology at BNI, in collaboration with the Community Action Group on the fight against mosquito plague (Kabs) in the past two years had approximately 75,000 mosquitoes in 55 locations in nine federal states collected - and finally found in three mosquito species from Brandenburg Dirofilaria repens. The researchers had entered uncharted territory with their mosquito study: „It is the first time that mosquitoes on parasites are being examined on a large scale in Germany, "said Egbert Tannich, which now makes „[...] warn scientists in good time about the spread of infectious agents and possibly prevent them from spreading“ could.

Dog Worm rarely dangerous for humans
In this case, the dog skin worm affects people only in rare cases, because the main reservoir of larvae are according to the BNI dogs, but in part also wild animals such as martens or foxes, in which the larvae would develop into mature worms. Since the development is temperature-dependent and lasts between 10 and 30 days, Germany was not considered endangered due to weather conditions, especially since mosquitoes live on average less than 30 days: „About 30 cases of this roundworm infection in humans have been detected in our institute in recent years - all cases were related to trips abroad“, Tannich's explanation.

Recently also infections in dogs in Germany
Accordingly, there have been infections with Dirofilaria repens so far, especially in southern Europe and in many countries in Africa and Asia, but in recent years, there are according to the BNI also repeatedly reports „in Austria, the Czech Republic or Poland, and more recently in dogs in Germany.“

Spread due to climate change possible?
According to Prof. Tannich, climate changes make it quite realistic that larvae in the mosquitoes could evolve fast enough at least in July and August - because the parasite was found in two consecutive years, „is suspected that at least in Brandenburg, a stable transmission already takes place, "Tannich continues.

Veterinarians must discover and treat infected animals quickly
Given the current situation, it is now particularly important that veterinarians discover as many infected animals and treat them quickly, because only this way, the further spread of the pathogen can be stopped, warns Tannich, because „Untreated dogs can carry the parasite for up to seven years.“

Dogs often show no symptoms
According to the BNI, detecting an infection would not be easy, as infected dogs would in many cases show no symptoms, but sometimes itching, a skin infection or a nodular change would occur. While the dog represents the main reservoir for the larvae, man as the so-called „accidental host“ on the other hand, it is more likely to be infected with mosquitoes by chance. Normally, the worms will spontaneously die after transmission. Therefore, in the case of infection, according to the BNI, doctors would in most cases only „migratory swelling and nodule formation on the skin [...] or early parasite stages on the eye“ which then have to be operated - in rare cases, however, syndromes such as meningitis in humans would occur, which then need to be treated with medication. (No)