Leverkusen – Alarm bells are ringing: the mild winter in many parts of the northern hemisphere is causing concern among many experts that a parasite plague is imminent. What’s more, tropical parasites are advancing further and further into temperate climate regions such as Europe or North America as a result of global climate change. The risk is particularly great for dogs, which often come into contact with ticks, sandflies or mosquitoes, because these parasites can transmit dangerous infectious diseases. That’s why suitable protective measures are becoming increasingly important.

The unusually warm weather had already considerably extended the activity of blood-sucking insects last winter. In addition to wild animals, the parasites mainly preyed on dogs walking daily with their owners. “We’re still removing ticks from the dogs week for week,” lamented veterinarian Dr. Barbara Dymond in mid-January on local television in the northeastern U.S. state of Pennsylvania, which has a temperate climate like central Europe. “Ticks have now become a year-round problem here, whereas tick season used to last from April to November.”

Mild winters do not just enable parasites such as ticks or mosquitoes to remain active for a longer period of time, however; in addition, a larger proportion of their larvae survive the cold weather. This means that a correspondingly greater number of parasite offspring are waiting to attack their warm-blooded victims in the spring. Young ticks often inherit the dangerous infectious agents directly from their mothers, as is the case with borreliosis, or Lyme disease, and babesiosis. These infectious agents are then transmitted to animals or humans while the ticks feed on their victims’ blood.

Yet pet owners in central Europe and the United States don’t just have to worry about an increased number of indigenous parasites such as ticks. In its “Global Environmental Change” report, the World Health Organization (WHO) conjectures that climate change could trigger the global proliferation and spread of parasites and the diseases they transmit. Parasites and infectious agents from warmer regions such as the Mediterranean, Central America and Brazil have already been observed spreading to central Europe and the United States.

In its 2005 report, for example, the French agency AFSSA mentions in particular mosquito species that can appear relatively quickly in new regions if the temperature and precipitation conditions change to their advantage. Such parasites include sandflies and various mosquito species that are spreading from the south to the north of France.

While mosquitoes can transmit worm larvae to dogs while feeding on their hosts, many sandflies carry the dangerous disease leishmaniasis, which attacks the animals’ immune system and blood vessels, but can also affect humans. Each year about 500,000 people are infected with this disease around the world. In dogs, the disease is often chronic and can even be fatal. Over the past fifty years, the sandfly has spread throughout Central America and southern Europe, and it has now also been observed in central Europe as well. Explains parasitologist Dr. Torsten Naucke from the University of Bonn, Germany, and member of the CVBD World Forum: “The sandfly advances into regions with an average yearly temperature above 10 degrees Celsius. This parasite has now successfully established itself along the River Rhine in Germany, partly as a result of climate change.”

Those who are not sure which parasites are active for how long in the region where they live should talk to their veterinarian. Parasite control products should be used for as long as the parasites are active, which in many regions now means year-round. Experts recommend the monthly application of a repellent parasiticide. Says Dr. Naucke: “Such products prevent ticks, sandflies and mosquitoes from biting dogs, which in turn reduces the risk of disease transmission.”

CVBD World Forum:

The CVBD World Forum is a panel of experts comprising leading scientists, veterinarians and physicians from Europe, the United States, Australia and Asia. It was established during the First International CVBD Symposium held in April 2006 in Billesley, United Kingdom, as a reaction to the global increase in canine vector-borne diseases (CVBD). The main goals of the CVBD World Forum are to promote the exchange of conventional and new knowledge about the interplay between ectoparasites, pathogens and their hosts; to describe and evaluate the distribution of parasites and pathogens in order to facilitate specific regional risk analyses; and to support suitable preventative measures. These activities are supported by the Animal Health Division of Bayer HealthCare. Further information can be found on the Internet at www.cvbd.org.

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