Published Date: 2017-01-20 17:23:00
Subject: PRO/AH> Bluetongue vector - Canada: (ON) Culicoides
Archive Number: 20170120.4780552
BLUETONGUE VECTOR - CANADA: (ONTARIO) CULICOIDES
A ProMED-mail post http://www.promedmail.org
ProMED-mail is a program of the International Society for Infectious Diseases http://www.isid.org
Date: Wed 18 Jan 2017 3:59:13 EST PM
Source: St Catharine Standard [edited]
Livestock disease insect has been discovered in Ontario. It was a disease incursion in September 2015 that injected fear in the farming industry and resulted in lost revenue. That's when a potentially devastating sheep livestock disease was confirmed to have entered the province. A farm animal in Chatham-Kent [municipality in Ontario] tested positive for the bluetongue virus -- a preventative response that followed, cost farmers millions of dollars.
"They found a sero-positive cow, and it was their first finding," said Brock graduate student Adam Jewiss-Gaines. "They found it, and it got people moving. There had been outbreaks in Europe that have been extremely costly."
Now, Brock University researchers confirm an insect that can transmit the devastating virus has made its way to southern Ontario. Jewiss-Gaines has found hundreds of Culicoides sonorensis -- or the biting midge -- after traps from Niagara [border between Canada and the US] to Chatham-Kent were examined. According to a Wednesday Brock release, the university team's investigation started in 2012, when Jewiss-Gaines found biting midges in a Thorold trap -- a species not expected to be found here. He and supervisor, medical entomologist Fiona Hunter, launched a project to see if the insect was within southern Ontario. Graduate student Larissa Barelli was also involved in the research and assisted with molecular work.
In 2013, Jewiss-Gaines then found biting midges in traps from Niagara to Sarnia. "I found the Culicoides sonorensis, which is the vector for bluetongue virus," he said. "And it wasn't previously thought to exist here." Further traps in southwestern Ontario the next year  caught more of those insects.
The discoveries troubled researchers who previously thought biting midges could not overwinter here. "It's very likely that we now have a vector for bluetongue (in Ontario) now," said Jewiss-Gaines.
Then, in [September 2015], the Canadian Food Inspection Agency reported the Chatham-Kent farm animal had tested positive for bluetongue. The result was [a] hit to the affected livestock industry which faced a temporary halt in international export transportation of live ruminants, including exports of bull sperm.
Cattle, goats and elk can be infected, but show few signs and act as hosts for the midge and lead to a spread to other livestock. The implication -- if bluetongue becomes an issue in Ontario, can cause "problems for farmers, with respect to specifically sheep," Jewiss-Gaines said, adding deer can also be affected.
According to the release, biting midges are not strong fliers, but wind currents from the United States may have brought the insect to the area. Another possibility is they arrived with a shipment of farm materials or livestock. The biting midge can carry the virus, which causes suffering and death, primarily in sheep and deer.
Signs include fever, a swelling of the nasal/ mouth area, a swollen, purple-coloured tongue, difficulty breathing and death. Some animals bleed at the feet. "There are indirect issues ... when animals get this disease," Jewiss-Gaines said. "It will also cause them to have to go through a lot of quarantine procedures, so it's hard to transport animals in and out of the farm, specifically out of the country."
Preventive measures include keeping livestock in barns in later hours when the midges are most active, and putting screens on barn windows.
Jewiss-Gaines said biting midges in general need to be studied further. "A lot of focus obviously goes to mosquitoes as they can transmit human (and other) diseases ... but I feel like biting midges need to be focused on more," he said.
The team's related research paper, "First records of Culicoides sonorensis (Diptera: Ceratopogonidae), a known vector of bluetongue virus, in Southern Ontario," was published in the Journal of Medical Entomology and can be seen online at http://bit.ly/2iMopqU.
[byline: Don Fraser]
[There are over 4000 species of biting midges in the Ceratopogonidae family, and over 1000 in just one genus, Culicoides. The distribution of midges in the genus Culicoides mis worldwide; 47 species are known to occur in Florida. Species belonging to the genus Leptoconops occur in the tropics, sub-tropics, the Caribbean, and some coastal areas of south east Florida.
The natural habitats of biting midges vary by species. Areas with substantial salt marsh habitat are major producers of many biting midge species. Additional sources for some species, like the bluetongue virus vector Culicoides sonorensis Wirth and Jones, include highly organic soil that is wet but not underwater such as those found with high manure loads in swine-, sheep- and cattle-farming operations. These insects do not establish inside homes, apartments, or inside humans or other animals.
Biting midges, primarily the species Culicoides sonorensis, are responsible for transmission of bluetongue virus to sheep and cattle in the US. Bluetongue is a serious disease of ruminants. Bluetongue viruses are found worldwide and are transmitted by different Culicoides species in different regions. Many countries that are bluetongue free prohibit the movement of livestock from bluetongue endemic regions. The annual economic damage in lost trade is in the millions of dollars.
Other animal disease causing pathogens transmitted by the bite of infected biting midges include African horse sickness virus in equines that is confined primarily to Africa and epizootic hemorrhagic disease virus in ruminants found in North America and principally having lethal effects on deer. Some equines experience allergic reactions to the bites, resulting in equine allergic dermatitis, affecting the withers, mane, tail and ears of the animal.
So while they may not establish inside homes, it is likely they could overwinter in a barn, especially in the manure within the barns. Indeed bluetongue virus has caused many livestock issues and losses. Canada is right to be alert and to be concerned.
Portions of this comment were extracted from http://entnemdept.ufl.edu/creatures/aquatic/biting_midges.htm. - Mod.TG
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