While the floodwaters from Hurricane Harvey start to recede, a new threat is due to hatch any day.

Pools of standing water make for excellent breeding grounds for mosquitoes. Until the waters are completely gone, most of the region is a haven for millions of mosquitoes and the diseases they carry.

Mosquitoes are known to carry a variety of diseases, ranging from malaria to West Nile to Zika.

More than 300 people in Texas tested positive for West Nile virus last year. Other positive tests have appeared in both humans and mosquitoes prior to the storm.

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According to some scientists, the risk of mosquito-borne diseases will be minimal in the immediate aftermath of the storm. Since mosquitoes often feed on birds carrying these diseases, the lack of a strong bird population after the storm could keep the chances of an outbreak down in the coming months.

However, a study of the aftermath of Hurricane Katrina in 2005 showed New Orleans residents experienced an outbreak of West Nile virus the following year.

“We can’t really say we’re out of the woods until much later,” said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston.

“Given all the West Nile we’ve already seen in Texas in recent years, this means we’re really going to have to keep our eyes on it in the coming months.”

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Scientists advise residents to stay inside during the dawn and dusk hours, as these are the times when mosquitoes are most active. They also recommend residents remove any pools of standing water.

While long sleeves and long pants can be uncomfortable in the Texas heat, they are also an effective means to prevent mosquito bites.

Mosquito-borne diseases could be the next threat to plague Harvey’s survivors AP Photo/LM Otero