Brown says the primary purpose of his job is to assess the number and types of mosquitoes in a given area, with the ultimate objective to have a better understanding of the concentration of mosquitoes that could potentially transmit diseases such as eastern equine encephalomyelitis (EEE) and West Nile virus to humans and equine.
Of the 61 species of mosquitoes that have been identified in North Carolina, Brown says that the trapping project is targeting species most likely to transmit EEE and West Nile to humans.
Called "bridge vectors" because they bite more than one species, these 24 mosquito types will bite both birds and humans. Of that number 17 types have tested positive for EEE in eastern North Carolina. Both EEE and West Nile are transmitted to equine species and humans by mosquitoes that have bitten infected birds.
Normally EEE is confined primarily to the bird population; however, in years of increased mosquito activity, such as this year, the larger population of bridge vector mosquitoes increases the likelihood of the diseases being transmitted to equine species and humans.
The extremely wet weather has contributed to the proliferation of all types of mosquitoes this year and as a result, mosquito-borne viruses have spread much more quickly than in normal years. As of Wednesday morning, 56 cases of EEE had been confirmed in horses in North Carolina, three of them in Bladen County.
Brown is setting traps in locations where West Nile or EEE has been detected either in the bird population or in equine species. (To date, no human cases of either disease have occurred in Bladen County.)
The trapping process entails several steps, Brown says.
"Once we trap the mosquitoes, we separate the targeted mosquitoes and separate them by type into different vials," said Brown. "We then send them to the state laboratory, which will furnish a spreadsheet that tells how many potential bridge vectors there are in Bladen County."
Brown said the trappings provide a snapshot in time of the concentration of bridge vector mosquitoes in an area at a given time.
"What we want to stress to residents of the area is that we are just moving into what is typically the most active part of mosquito season," said Brown. "I haven't seen this much (mosquito) activity in southeastern North Carolina since I've been in this capacity-about 10 years."
Brown explained that the traps work by using a combination of light and dry ice to produce carbon dioxide.
"Some mosquitoes are attracted to light, others by carbon dioxide," Brown said. "The mosquitoes are attracted to the light source and carbon dioxide, which pulls them into a fan and into a collection area. We return to the trap on the morning after it is set and get the mosquitoes. I take them back to the lab at my house where they are sorted."
Bladen County Health Director Myra Johnson said the work of the Pest Management section to trap the mosquitoes is very important, in that it can provide vital information on the mosquito populations and help alert the public of concentration of bridge vector mosquitoes in the area.
"This year it is particularly important because of the number of cases of EEE and West Nile that have occurred across the state and here in Bladen County," Johnson said.
"The intent is not to alarm the public but to remind them of the importance of taking precautions during this time of increased mosquito activity," Johnson said.
"Though the likelihood of humans contracting either of the diseases is still very small, the diseases are obviously present in our mosquito populations, and we need to take precautions to prevent being bitten," she added.
"Individuals should avoid going outside as much as possible during the dusk and dawn periods when mosquitoes are most active," said Johnson. "They should also wear long-sleeved shirts and long pants when mosquitoes are active.
"Mosquito repellent with DEET should also be used. Users of DEET-based products should be sure to use manufacturers' directions.
"Screens on windows and doors should be tight and in good condition," she added.
Johnson also said it is important to eliminate mosquito-breeding areas as much as possible, by tipping containers that hold water such as buckets, old tires or other containers. Gutters should be kept clear and in good repair, as well.
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