Updated 2/12/2020
A persons chance of becoming severely ill from West Nile Virus is very small. “The risk is very low. Even in areas where the virus is circulating, very few mosquitoes are infected with the virus. Even if the mosquito is infected, less than 1% of people who get bitten and become infected will get severely ill. The chances you will become severely ill from any one mosquito bite are extremely small.” From the CDC website: “Most people (8 out of 10) infected with West Nile virus do not develop any symptoms.” [1]
Data from the Texas Department of State Health Services website for a period of 18 years (2002 thru 2019) show that there was a state wide annual average of 329 human cases of West Nile Virus infections. With an average population of 26,917,162 during that time period calculates to 1 in 77,112 chance of contracting West Nile Virus. The state wide annual average of deaths during the same time period was 18 for a 1 in 1,452,848 chance of dying from West Nile Virus. In 2019 there were 32 statewide total infections and four deaths. An individual’s chance of contracting or dying from West Nile Virus is extremely unlikely.
Compare that with pneumonia and influenza. For the 2015-2016 and 2016-2017 flu seasons there 8,415 and 10,955 deaths respectively. For the 2015-2016 flu season a person had a 1 in 3,356 chance and for the 2016-2017 season had a 1 in 2,629 chance of dying from pneumonia and influenza. On average someone is over five-hundred times more likely to die of the flu than West Nile Virus.
Michael Gochfeld, Professor of Environmental and Community Medicine at the Robert Wood Johnson Medical School and School of Public Health puts it into perspective by saying “In weighing the risks and benefits of mosquito control, we should also consider the disease itself and the risk to the human population. The media always paired the words “lethal” or “deadly” with “West Nile” or “encephalitis,” reinforcing in the public’s mind the danger from the disease. But it would be equally appropriate to characterize West Nile Virus infection as “in apparent,” “usually asymptomatic,” or “occasionally serious.” Seven deaths in a population of over 10 million people over a one month period is certainly tragic, but pales besides the number of deaths from many other diseases that are addressed less aggressively.”
This graph from the CDC website shows the average nationwide annual incidence of West Nile virus neuroinvasive disease by age group from 1999 to 2017. The graph is interpolated in the table below.
Age Group | Chances of Contracting Neuroinvasive WNV |
Less than 10 | 1 in 2,500,000 |
10 – 19 | 1 in 1,100,000 |
20 – 29 | 1 in 625,000 |
30 – 39 | 1 in 385,000 |
40 – 49 | 1 in 238,000 |
50 – 59 | 1 in 182,000 |
60 – 69 | 1 in 154,000 |
70 or Older | 1 in 87,000 |