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County vector control inspectors have now collected as many mosquitoes infected with West Nile virus as were collected all of last year, according to the Department of Environmental Health. This year could be a tough one for the potentially fatal disease in the county.

The number of dead birds testing positive with West Nile virus rose sharply in May, from 5 to 29, and continues to rise, says the department. The number has gone up to 33, by far the highest of any California county. San Diego didn't reach that level until November of last year.

The new batches of infected mosquitoes were collected near Jamacha, close to the Lemon Grove border. Traps were placed there because the number of infected dead birds was high.

Last year, 11 county residents were diagnosed with West Nile virus and 2 died. Statewide, 31 died of the disease.

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ImJustABill June 18, 2015 @ 7:45 a.m.

I would have hoped a silver lining to the drought would be fewer places for mosquitos to breed.


Don Bauder June 18, 2015 @ 10:19 a.m.

ImJustABill: That's exactly what I thought until I saw these stats. Dryness is apparently only one of the variables in play here. Best, Don Bauder


danfogel June 18, 2015 @ 11:05 a.m.

don bauder mosquitos can breed anywhere there is standing water in as little as a table spoon. Think of a discarded water bottle cap. Or in the saucer of a potted plant. Or in a plastic bag hidden by a plant. You probably don't do much yard work around your house, but how about a shovel that's lying on the ground or a dent in the bottom of an overturned wheel barrow. You get the idea.


Don Bauder June 18, 2015 @ 9:57 p.m.

danfogel: But is it not true that you will be exposed to mosquitoes more frequently in a wet climate -- a place where there is more standing water? So statistically, it would seem to me that a dry year might produce fewer mosquitoes than a moderately wet one, keeping in mind that climate is apparently only one factor in likelihood of getting West Nile virus. If I am wrong, please explain. Best, Don Bauder


danfogel June 19, 2015 @ 9:34 a.m.

don bauder, all good questions. But being that I'm not an expert on either mosquitoes or west nile virus, I can't answer them. However, according to CDC stats for 2014, Washington and Oregon had a 12 and 8 total cases, respectively, with no deaths. In comparison, Arizona had 107 cases and 13 deaths, while California had 801 total cases and 31 deaths. Minnesota, which I have been told is terrible for mosquitoes in the spring and summer, had 21 total cases and no deaths. Interpret that data however you want. CDC data for 2015 says that as of June 16, California, and Colorado for that matter, have had only non-human WNV activity, while Arizona Oregon and Washington have had no activity at all. Again, Interpret that data however you want. One other set of stats for you. Again according to CDC data, from 1999 thru 2014 Washington had 63 total cases, Oregon 167 cases, Arizona 1,436 cases, Minnesota 635 cases and California 4806 case, which by the way was second only to the 5112 cases found in Colorado. As before, you can interpret the data however you want.


Don Bauder June 19, 2015 @ 11:48 a.m.

danfogel: Very interesting information. It's too early to declare that there is little or no relationship between the wetness/number of mosquitoes and the incidence of the virus. But the data you provide suggest that the drought won't keep down the incidence of the disease.Best, Don Bauder


Ponzi June 18, 2015 @ 2:42 p.m.

There are probably many pools that homeowners or renters have let go green. Spring Valley still have a miles long open storm drain system that, when it is not rushing with water during a rain, stalls to a stop and there are many pools of stagnant water. I have extra trash cans I use for gardening and I have to turn them over after a rain to dump all the water out. How many households are not emptying cans, buckets and other objects that have stagnant water?


Don Bauder June 18, 2015 @ 9:58 p.m.

Ponzi: All these would seem to be good explanations of what is under discussion. Best, Don Bauder


Twister June 19, 2015 @ 10:05 a.m.

Good "explanations," but not enough.

When I first checked with CDC data after the initial introduction, the data indicated a "wave" of infection from east to west, with cases increasing successively westward and falling off in the east. Surely some vector ecologist(s) has studied the ecological dynamics of this phenomenon . . .

Counter-intuitive data usually means that the intuition had a glitch in it, but sometimes the data are inadequate.

The interactions of populations of host species can produce some odd-appearing phenomena--it's a tangled web. I'm not surprised to see more cases in AZ and CA than OR, for example; more mosquito populations and activity in warmer areas/times than cooler, the number of hosts and their interactions.

You're right that a small amount of water can produce mosquitoes, even in stream eddies. What should have been done was a study of the mosquitoes themselves, especially for the presence/absence of the virus. Yes, keep standing water out of your area. Look up studies on the distance mosquitoes can fly too (nts).


Don Bauder June 25, 2015 @ 8:52 p.m.

Twister: Data on Arizona and California compared with Oregon suggest that human population may play a role. We haven't determined if mosquito population plays a role. Best, Don Bauder


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