U.S. West Nile Virus update, 03 November 2012: Climate change favors the Vectors! Idaho ground zero for NorthWest? More victims don’t remember being bit by mosquitoes, evidence that it can be passed from human to human? Horse cases 372% increase! California chickens in the coal mine cases continue to go up! WNV tests not accurate!

“As of October 30, 2012, 48 states have reported West Nile virus infections in people, birds, or mosquitoes. A total of 4,891 cases of West Nile virus disease in people, including 223 deaths, have been reported to CDC.”-U.S. Centers for Disease Control and Prevention

You can increase the CDC’s West Nile death toll, because the week following the CDC’s latest report Louisiana reported one more human death, along with 13 new cases (two with the potentially fatal neuroinvasive version).  The southern state now has 338 official human cases.

Louisiana health officials said one of those recently infected has no symptoms.  Officials are pointing out that just because you have no symptoms doesn’t mean you’re not infected.  Detection is made only during health exams or when the infected person donates blood.

Oklahoma now reports at least 176 cases, 12 deaths. One 36 years old man has been in the hospital fighting West Nile for three months.  He said his only symptom, prior to going into the hospital, was a stomach ache.  Veterinarians reporting 39 horse cases, a huge increase.  Back in August there were only two horse cases.

On 31 October, it was reported that Maine has its first human case of West Nile virus.  Health officials say the person recovered.

Pennsylvania reporting two more cases. County health officials blame climate change: “It was mostly due to the weather. The warm, dry conditions were perfect for the culex mosquitoes that carry the virus.”-Karen Tobin, Erie County West Nile virus coordinator

As of 30 October, Alabama reporting 41 cases. That’s based on data from U.S. Department of the Interior/U.S. Geological Survey (USGS).

The problem is that the USGS West Nile virus map is inaccurate.  Here’s an example why: At the end of August Montana reported three new cases in Yellowstone County. Yet, the USGS map, as of 30 October, still does not show those three cases.  It only shows cases in Chouteau, Custer, Prairie and Richland counties!

At the end of October, an Emmett, Idaho, man was hospitalized with the neuroinvasive type of West Nile. That makes 16 human cases for the gem state.

Idaho seems to be in the middle of the northwest West Nile outbreak.  Here’s what the surrounding states are reporting:  Montana has at least eight cases. Wyoming reporting at least seven cases.  Utah reports at least five cases (as of 17 October). Nevada reports seven cases.   Oregon three cases, the latest case got infected in IdahoWashington four cases, two from out of state (they didn’t say where). 

Officials in Oregon remind everyone that mosquitoes can survive in cooler weather: “Our climate here in Eugene is very mild, so we have mosquitoes seven, eight months out of the year. That season is almost over, but not completely over.”-Patrick Luedtke, Lane County Public Health

Health officials in Nevada also reporting increased number of infected mosquitoes.  However, the latest West Nile survivor says climate conditions are not right for mosquitoes, and he never saw any: “I don’t remember seeing water in that wash hardly at all. I’m from the South, so I’m used to mosquitoes, and that’s one of the reasons why we like it here because there’s not a lot of bugs and stuff.”-Leslie Petrasich, Las Vegas resident for past six years

There are many other victims who’ve reported not seeing any mosquitoes, or not remembering if they were bit.

As of 02 November, California reports 38 new human cases. The golden state has 377 human cases, so far 15 people have died. Health officials also report 21 horse cases.  11 dead birds were positive for the virus, bringing the total to 1,614 dead birds with West Nile.  Chickens used to test for disease (called sentinel chickens) are continuing to show West Nile is not finished.  15 new cases showed up in sentinel chickens, for a total of 507 cases.  Two new cases of infected squirrels, for a total of 21 squirrel cases.  Mosquito testing shows no end in sight for West Nile; 22 new positives, for a total of 2,814 positives.

In Grand Junction, Colorado, voters will be deciding if they want to pay an extra tax to fight West Nile virus.  It’s called measure 5B and it directly affects property taxes: “For every $100,000 of property that’s assessed, their taxes will raise $12.04. This is a never ending tax.”-Sandra Parker, opposed to new tax

As of 29 October, the Colorado Department of Public Health and Environment reports 129 human case and three deaths.

Texas, the state with the most cases, reporting 1,683 human cases (77 deaths).  Recently, some West Nile victims asked local health officials why they didn’t start mass spraying against mosquitoes sooner.   It was revealed that the CDC recommended spraying back in July, but local officials didn’t start spraying until almost a month later.  In Texas, a county judge must authorize such an operation. The judge for Dallas County says local health officials said nothing to him about aerial spraying until 06 August.

Texas also has at least 72 horse cases.

As of 10 October, the USDA Animal and Plant Health Inspection Service (APHIS) reports 400 horse cases across the country. That’s a 372% increase over last year!  Only seven states seem to be unaffected by equine West Nile virus.

On 02 November, a South Dakota news source published an interview with a researcher who said the West Nile epidemic is all about climate change: “We look at accumulated temperature and moisture conditions.  Temperature affects the rate at which the virus amplifies in bird populations.  When the mosquito bites the bird and acquires the virus, it goes into the mosquito’s stomach.  There’s a time lag before that mosquito is infected and can retransmit.  So when we get an early spring, transmission starts early.  Warmer than normal temperatures reduce this extrinsic incubation period in the mosquito.  Then there are more cycles that occur in mosquito and bird populations, more opportunity for the infection rates to build up to higher levels before summer and the disease spills over into the human population.  And of course you need water, you need rainfall, or, more specifically, you need puddles, water on the ground for mosquitoes to breed in.  But the moisture link is tricky because different types of mosquitoes breed in different types of water bodies. [example] Culex tarsalis is not a floodwater mosquito, so it doesn’t necessarily bloom in population after a huge rain.”-Mike Wimberly, South Dakota State University

In Nebraska, a retired professor reported that overall mosquito counts there were actually down from prior years. He says what is happening is the climate change is killing off many mosquitoes, except for the ones that carry West Nile.  It seems climate change is favoring the virus carriers, vectors are on the increase: “There were more positive mosquitoes even though we’ve had fewer mosquitoes than the previous two years…..The mosquitoes that were here were the bad ones.”-Randy Lawson, mosquito hunter

One of the major problems in detecting West Nile cases is that current tests can confuse other diseases, such as St. Louis encephalitis and dengue fever, because they are so similar.  An Arizona professor says he has the answer; plants: “Our test will improve the accuracy of diagnosis, leading to the proper treatment of patients affected by WNV.  The plant derived monoclonal antibody we examined is not only low cost, but highly specific for WNV antigen and does not recognize antigens from other flaviviruses.”-Qiang “Shawn” Chen, Arizona State University