do begin with the growing concerns over the west nile virus across so many states now and we learned late today that the spraying in dallas has now been halted tonight because of the weather and just... See More
do begin with the growing concerns over the west nile virus across so many states now and we learned late today that the spraying in dallas has now been halted tonight because of the weather and just as we learned of this new delay we're getting a clear picture how concerned the federal authorities. Centers for disease control con now reporting 26 deaths so far. Nearly 700 confirmed cases. That's more than three times the normal number at this point in the year. I wanted to widen out and show you how wide spread it is. We'll light up the map in red. 43 states in all reporting the cases of the virus, as i mentioned more states growing at this hour and ground zero in dallas where ten people have died tonight. Bad weather again forcing authorities to suspend the spraying. We begin tonight with meteorologist ginger zee. Reporter: Breaking in, spraying down. Tonight our nation is in assault mode. The mission -- eliminate mosquitoes that could carry the west nile virus. In carollton, texas, they are busting into abandoned pools and cleaning them out. That way, mosquitoes can't breed in stagnant water. In new mexico, north carolina and illinois, it's a spray that they hope will protect. Went to bed that night, and the net morning, I woke up and i was blind. Reporter: That's hal dalton, oklahoma's first confirmed human case this year, he is one of the facial's almost 700 infeed with the virus. With at least 26 people dead, this is the worst outbreak in the west nile virus this early in the seaver. Ground zero this year, dallas, texas -- there's no question that there's something different going on in texas this year. We would not call this a major epidemic. Reporter: So, no need to panic says columbia university's west nile expert, dr. Ian lipkin, but no time for complacency either. This is enough for mosquitos to develop? It doesn't take much standing water -- even with a volume like this is sufficient -- to allow mosquitoes to breed. aerial attack with pesticides was again grounded today because of rain and thunderstorms. Interestingly enough, this year's drought could be playing a factor in the increase of west nile virus cases. Now, one of the things that happens in drought years is that people tend to collect water 'cause they want to be able to save water. So, when this occurs, you have perfect breeding grounds for mosquitoes. Reporter: In frisco, texas, ginger you were telling me tomorrows start to dry out tomorrow? Yes, and monday and tuesday will be much better sprague days in dallas. Dusk and dawn is when the critters come out. Remember that's the time to avoid coming outdoors. See you first thing on "gma." West nile concerns for tonight. We turn to another health threat we reported on the salmonella outbreak. That's now spread to 20 states. 2 people have died.
This transcript has been automatically generated and may not be 100% accurate.