The Zika virus and Chester County

Getting rid of standing water is more effective than spraying

By Nathaniel Smith, Columnist, The Times

NSmithColLogoNews has come around lately that “Pennsylvania Is Now One Of The Top States With Zika Virus ” (Phoenixville Patch, 8/23/16). Currently PA ranks 5th in the number of diagnosed Zika cases. Of course, no one knows how many undiagnosed cases there are anywhere.

Quick quiz: how is Zika spread? If you answered “by mosquitoes,” you’re only half right.  It’s our fault too.

It’s important to focus on this note in the article: “All of the cases were travel-related, according to the Centers for Disease Control and Prevention.”

That means no human has acquired Zika from a mosquito in PA. Although the prime mosquito host for Zika, aedes aegypti, does exist in Pennsylvania, it doesn’t do well this far north (yet).

The fact is that Zika is spread not only by mosquitoes but also by people, whether through sexual contact (CDC offers explicit advice on this aspect) or from carrying the virus (usually without symptoms) and being bitten by a mosquito that in turn bites someone else, who thus acquires the disease. The aedes albopictus mosquito, often called “Asian tiger,” has become very numerous in PA but fortunately does not seem to transmit Zika very well (yet).

Spraying pesticides is a limited, short-term fix that leaves many adult mosquitoes alive and does not affect eggs and larvae but harms many forms of life and can lead to acquired immunity. Mosquitoes breed over 500 times faster than people, so they will become immune to whatever we do against them much faster than we can evolve to resist them. Mosquitoes in Puerto Rico and Florida are already becoming resistant to permethrin, the standard anti-mosquito pesticide.

This is all not good news, except that in PA we do have some time to get ready for present and future mosquito-borne diseases.

Mosquitoes don’t know what they are doing but people do; mosquitoes follow their instincts in a short life cycle but people have the power of reason and the advantage of experience.

It is very hard to tell who is carrying the Zika virus, because serious symptoms are rare. But anyone who has traveled to a place here Zika is common could be carrying the virus. In Pennsylvania today, mosquitoes don’t carry Zika, people do.

What can we all do, beyond keeping an eye on people who just got back from Brazil, Puerto Rico, or Miami? (And those people have a special duty to get their blood tested and avoid being bitten by mosquitoes here at least while their blood might be contagious, which seems to be for about a week.)

The best solution is to reduce the number of mosquitoes: to cut down on mosquitoes and all diseases they carry, we should GET RID OF ALL STANDING WATER ON OUR PROPERTY!

And communities need to educate their residents. For more, see

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