FORT WORTH (CBSDFW.COM) – COVID-19 could be overshadowing another seasonal disease that sometimes comes with similar symptoms.

Health officials repeated warnings this week about the increase in West Nile positive mosquitoes across North Texas.

Tarrant County leads the state with 235 positive samples so far. Dallas, Denton, Collin and Johnson counties have also had positive mosquitoes.

However, just two human cases have been discovered so far, one each in Tarrant and Dallas, with one of them resulting in a death.

Both viruses can arrive with fever, fatigue and body aches. With the focus still firmly on COVID-19 however, a negative test for that virus could potentially mean another troublesome virus could be overlooked.

“If somebody comes into the ER with a fever or a headache and body ache, we should be looking for COVID-19,” said Dr. Priya Subramanian, an infectious disease specialist at Medical City North Hills. “But since West Nile is also on the radar during the summer months, we as health care professionals we are trained, to have that in the differential diagnosis and look for that as well.”

West Nile is only transmitted to humans through mosquitoes, and only one in five people infected will show symptoms, Dr. Subramanian said.

With the virus a concern again though, she said people should at the least make a phone call to their medical professional if they have been in mosquito-prone areas and are showing symptoms of the virus.

Texas Department of State Health Services data shows there have been at least five cases this year, including four in Tarrant County, where blood donations have later tested positive for West Nile, even though the donors had no symptoms.

“There’s certainly concern there of people trying to get tested for COVID because that’s been in the news so much, and missing out that they might have another illness because they tested negative for COVID,” said Vinny Taneja this week, the public health director for Tarrant County.

He has been urging residents to take care of mosquito breeding grounds in their own yards, and suggested aerial spraying may need to be considered if the trend in positive mosquitoes didn’t change soon.

“We’re in trouble here if we don’t collectively take action,” he said.