by George Looby, DVM
As if the current tick borne diseases that citizens in the northeast have to contend with were not enough, a new one is emerging to make life in the out of doors a bit more challenging. Lyme disease has been with us for several years and there are few who are not familiar with some of the issues that can arise from being infected with the spirochete that causes the disease.
The recently emerging disease is called Powassan virus and it was named after the town of Powassan, Ontario where a young boy died of the disease several years ago. At this time it is the only known tick borne flavivirus in North America which can infect humans. There are six species of ticks that are known to transmit this virus one of which is the same tick, Ixodes scapularis, that is responsible for the transmission of Lyme disease.
The transmission time for this disease is rapid, something on the order of 12 hours whereas that of Lyme disease is more than twice as long. The initial symptoms include headache, fever, nausea, occasional confusion and weakness. Those individuals infected with this virus and showing severe symptoms should be hospitalized to receive supportive treatment. There are at this time no specific medications or vaccines available to treat or prevent the disease. Treatment should be directed at reducing brain swelling, respiratory support and IV fluids. Left untreated these severe cases may progress to meningoencephalitis that may have symptoms including seizures and altered brain status.
Just how the blacklegged tick picked up the virus that causes Powassan Disease is unknown but scientists working at the Connecticut Agricultural Experiment Station (CAES) in New Haven are certain that if it had been present years ago they would have detected it. This is based on the years of study and detection of Lyme disease that they have conducted since the 1970s. One assumption is the deer tick might have picked it up in the burrow of a skunk or badger where another member of the tick family has been known to carry the virus spreading it among members of the weasel family. That tick, unlike the deer tick, does not have a strong taste for human blood, content to feed on lower members of the mammalian family.
One factor that has contributed to the increase in the number of ticks is the changing weather patterns. The past two winters have been especially mild in the northeast and this has sent tick populations soaring. As climate change continues this pattern is likely to follow suit. In some areas the amount of land under cultivation has decreased leading to either reforestation or housing developments or a combination that brings more of the population in contact with tick habitat. Researchers at the CAES have been collecting samples of deer blood brought in by hunters over a 40-year span and it is only recently that samples have begun to show antibodies to the POW virus. Staff member Goudarz Molaei conducts the tick-testing program for the CAES in which residents who are bitten by ticks may send them to his lab and have them tested for the presence of diseases such as Lyme. Severe budget constraints at the state level make it impossible for him to expand his testing program to include diseases such as POW. The number of submissions to his lab has increased dramatically over the past two years from about 50 a month in 2014 to as many as 200 a day this year.
There is no magic formula for avoiding tick bites if you are working or playing in an area in which they abound but here are a few well-proven measures that one can take to lessen the likelihood of being bitten. These have been repeated many times but bear repeating: wear long sleeves and pants when in suspect areas and use repellents on your skin, gear and clothing.
Just when you thought that problems with insect pests couldn’t get much worse you find that once again you were wrong. If we dare say that climate change is real then we are about to play host to yet another insect that seems to find the increase in the average daily temperature in the northeast to its liking.
A mosquito given the name Aedes albopictus or Asian Tiger Mosquito originated in East Asia and probably arrived in this country via plane or ship at some point in the not too distant past. One of its more unpleasant characteristics is that it is an aggressive biter of humans and may carry one of several human diseases. Among these are West Nile and Cache Valley viruses which have been found in mosquitoes in Connecticut. The CAES monitored mosquito activitity from 1997 to 2016 in a state supported program to determine the level of mosquito borne diseases. The Asian Tiger Mosquito was first detected in 2006 and then from 2010 to 2016 at several locations with local overwintering and increasing abundance and distribution each successive year, especially following mild winter conditions.
To add to the overall misery the first mosquito to test positive for West Nile Fever was reported from the station on June 29 and Station Medical Entomologist Dr. Phillip Armstrong said that further build up of the virus can be expected from now well into September. Last year the station trapped and tested over 170,000 mosquitoes at trap sites in 20 towns in four counties and identified WNV positive mosquitoes in each of the of them. Since 2000, 131 cases of WNV have been diagnosed in Connecticut with three fatalities.
In response to the ever-increasing problem with mosquito transmitted diseases the state has developed a mosquito management program. This is a collaborated effort among several state agencies including the Department of Energy and Enviromental Protection (DEEP) the CAES, The Dept. of Public Health (DPH), The Dept. of Agriculture and the Dept. of Pathobiology at UConn. These agencies are responsible for monitoring mosquito populations and the potential public health threat of mosquito borne diseases. The CAES maintains 91 mosquito-trapping stations in 72 towns and throughout the state with the trapping and testing season running from June into October.
To minimize the risk of being bitten wear light colored clothing with long pants, long sleeves, shoes and socks and especially during the dusk to dawn period when they are most active.
A new tick borne disease and other nasty insects
by George Looby, DVM