What is West Nile Virus? 

West Nile Virus (WNV) is a mosquito-borne disease typically transmitted to people through the bite of an infected mosquito (which gets the disease from and infected bird), and is the most common mosquito-borne disease in the United States. All states other than Hawaii have now reported cases of West Nile Virus within their boundaries. Although only about 20% of people infected with WNV will develop adverse symptoms such as fever and less than 1% will develop serious or potentially fatal symptoms, the risk of exposure is of particular concern because there are no vaccinations to prevent or medications to treat West Nile Virus. 

Symptoms of West Nile Virus...

One of the complications with diagnosing cases of West Nile Virus is that infected people only show symptoms about 20% of the time. According to the CDC, about 1 in 5 people who are infected develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash...and only about 1 in 150 people who are infected develop a severe illness affecting the central nervous system such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord). Of the less than 1% of people who develop severe symptoms, less than 10% of those will die. 

How is West Nile Virus Spread? 

West Nile Virus (WNV) is most commonly spread to humans through the bite of an infected mosquito who became infected by biting an infected bird. The disease is ultimately transmitted from the bird to the human through the mosquito. In very rare cases, WNV has also been known to be transmitted through certain medical procedures such as blood transfusions or organ transfer. West Nile Virus is not transmitted from person to person, through coughing or sneezing, or through handling or eating infected birds or other mammals. 

How Is West Nile Virus Prevented? 

The best defense against West Nile Virus is to minimize your risk of exposure to mosquitoes. If possible, avoid spending time in mosquito-infested areas. When avoidance is not practical, be sure to wear long sleeve shirts, long pants, and protective coverings over as much of your exposed skin as possible, and combine those efforts with quality mosquito repellent products to reduce the likelihood of getting bitten. Around your home, take measures to modify the environment so that it is not suitable for mosquito reproduction or adult mosquitoes to thrive. Eliminate any potential sources of standing water, and treat any remaining ones with a mosquito larvicide in order to prevent your property from becoming a mosquito breeding site. Also consider a mosquito abatement program to reduce active populations of adult mosquitoes during the mosquito season. 

8 Deadliest West Nile Virus States in 2018

According to CDC data, these 8 states had the most reported cases of West Nile Virus in 2018 which resulted in death (view full WNV report). As an important reminder, about 80% of WNV infections are accompanied by no symptoms whatsoever, meaning that the overwhelming majority of cases are certain to go unreported or undocumented. It is therefore probable that most of the cases being reported to the CDC are ones where symptions and reactions were severe enough to warrant medical attention and documentation, leading to the percentages of death being much higher than customary with this reported set of data. In actuality, only a fraction of 1% of people who contract West Nile Virus will eventually die from the disease.

#8 Ohio: 6 Deaths | 65 Cases

Of the 65 reported cases of West Nile Virus in 2018, 6 of them resulted in death. That means 9.2% of individuals who reported getting the disease eventually died from it. Ohio is positioned in the midst of several other even more deadly states as you'll soon discover. 

#7 New York: 6 Deaths | 90 Cases

Also with 6 documented deaths from West Nile Virus in 2018, we gave New York the edge over Ohio because they had nearly a third more reported cases overall. That said, Ohio has about 8 million fewer people than New York state, so this data can be sliced a number of ways. Either way, if you live or travel in New York or Ohio, the risk of exposure to WNV is ever-present.  

#6 Virginia: 7 Deaths | 47 Cases

Coming in at the 6th deadliest West Nile Virus state in 2018 is Virginia, stemming from just 47 total reported cases. Frighteningly, 14.9% of the total WNV cases reported resulted in death. The takeaway...if you live in Virginia, get bit by a mosquito, and start showing signs of West Nile Virus, maybe you shouldn't report it to the CDC. 15% of those that reported in 2018, died!

#5 Pennsylvania: 8 Deaths | 119 Cases

Yep, mosquitoes are found in Pennsylvania too, and people seem to be dying from West Nile Virus there at an alarming enough rate for this state to make it into the top 5 deadliest states. If Pennsylvanians are looking to escape WNV, just don't head north are west, as Ohio and New York are nearly as dangerous. 

#4 California: 8 Deaths | 204 Cases

Just like Pennsylvania, California suffered 8 deaths at the hands of West Nile Virus in 2018. We gave CA the deadliness edge because it had nearly 100 more reported cases of the disease during that time. But with about 28 million more people than Pennsylvania, the exposure risk per person in PA would actually be quite a bit higher than in CA. Nevertheless, take mosquito precautions in both states.  

#3 Michigan: 9 Deaths | 102 Cases

This data tells a similar story with Michigan as it does for some of its nearby states such as Ohio, Pennsylvania, and New York. Those living in or around these states would be well-advised to take the mosquito threat seriously, as deaths from West Nile Virus in Michigan are more likely than in 46 other states. 

#2 Nebraska: 11 Deaths | 245 Cases

Now at number 2, things really start to get interesting. With less than 2 million people in the entire state, Nebraska is the 37th most populous state in the country, having about 37 million people less than California. And yet it had the 2nd most West Nile Virus related deaths in 2018 of any state, and more reported WNV cases than any other state. Of interest to note is also that nearby states of North Dakota, South Dakota, and Iowa were also among the top 10 in reported west nile virus cases in 2018, but didn't make this list due to fewer instances of death. Nevertheless, it does seem to suggest that the area around the Great Plains has a particularly high presence of West Nile Virus that should be accounted for by those living there or traveling through. 

#1 Illinois: 16 Deaths | 172 Cases

And the winner is...Illinois! In 2018, the CDC reported that 16 people died in Illinois from complications directly associated with West Nile Virus, making it by far the deadliest state for WNV in the country. It may be of additional interest for those in this area that Chicago consistently ranks as among the buggiest cities in America for things like bed bugs, ticks, and rats as well. So if escaping bugs is the mission, the friendly confines of Wrigley Field may not be so friendly after all.  

Final thoughts...

As our population continues to grow, so too are we likely to face growing threats from West Nile Virus and other mosquito-borne illnesses. Worldwide, mosquitoes remain the deadliest animal on the planet. Mitigating mosquito populations very much depends on the involvement of as many people as possible, each doing their small part. If you don't currently have one in place, please consider implementing a mosquito reduction program on your property.