Health officials are on their toes as they are expecting West Nile Virus to come back as summers make mosquitoes thrive on the weather conditions.

Mosquitoes, especially culex mosquitoes, are more harmful to people after they bite.

There were about 127 cases of WNV in 2004, and about four deaths occurred in Mesa County.

The WNV is spread after mosquitoes bite birds that belong to the corvid family and these birds are coming back that were wiped out in 2004 by the virus which has made these officials more worried about the virus returning. The birds that belong to the corvid family are crows, ravens and magpies.

The virus had however showed weaker presence in recent years as there were no reported cases in 2008 in Mesa County and in 2009 there were two reported cases and only one person had died.

This year there has been one case of WNV and this has been reported by the Colorado Department of Public Health and Environment on Friday.

Mesa County Health Department spokeswoman Kristy Emerson said that with bids from the corvid family coming back there is a scare that the virus would show up again.

She said, "Culex mosquitoes like the hot temperatures. Usually we see more in July, August and September."

Officials said that the disease can be kept at bay by taking precautions.