West Nile Virus on the Rise in 2022

“West Nile virus is commonly spread to people by the bite of an infected mosquito.” Source: CDC

West Nile Virus, the virus that causes West Nile fever, dominated the epidemiological news space for most of the second half of the 20th century. Mainly spread by mosquitos, it is one of the most prominent tropical diseases in the world, with up to a 10% risk of death in those that develop the fever. As the vector, mosquitos, is highly dependent on ideal conditions like warm, damp environments, climate change has the potential to drastically increase the spread of the virus. West Nile has recently been in the news again as infections have been reported in Suffolk and Westchester Counties in September, as well as several cases detected in New York City in August, prompting efforts to curb transmission. 

West Nile Virus traces its origins back to 1937 when it was first detected and isolated in a patient in the West Nile district of Uganda. It was not until the 1950s, during an outbreak in Egypt, that the ecology of the virus was better understood by the scientific community. Researchers were able to conduct studies  to isolate the virus from ones with similar structures, symptoms, and outcomes. The most high-profile outbreak of West Nile Virus occurred in 1999 in New York City, where the virus subsequently spread to 44 additional US states – almost 2,000 people have died from infection across the country since the start of the outbreak. Interestingly, at the time of the West Nile outbreak of 1999, the virus was formally declared as a federal emergency by the US government. 

As mentioned, the virus is spread via bites from infected mosquitos. Symptoms include typical flu-like symptoms like headache, fever, muscle weakness, and nausea, as well as disorientation, head fogginess, and in serious cases seizures, paralysis, or coma. According to the New York Department of Health, up to 80% of those infected never show symptoms. At the moment, there is no treatment specific to West Nile Virus except for hospitalization in serious cases; there is also currently no vaccine against the virus. Prevention options include utilizing mosquito repellant, minimizing exposed skin while outdoors, and reducing the ability for mosquito populations to thrive in your immediate area, which means limiting water-holding containers and areas where water can accumulate.  

• Symptoms

  • No symptoms in most people (8 out of 10)

  • Fever in some people (1 out of 5)

  • Severe symptoms in a few people (1 out of 150)

    • High fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis

    • Vulnerable populations:

      • People with pre-exisiting health conditions (i.e., cancer, diabetes, hypertension, kidney disease)

      • Elderly over 60 years old

      • People who have received organ transplants

    • Some people (1 out of 10) who develop severe symptoms affecting the central nervous system die

• Diagnosis

  • See your healthcare provider if you developed the symptoms described above

  • Your healthcare provider can help you test for West Nile virus infection (learn more about the testing)

• Treatment

  • No vaccine or medicine are available at the moment

  • Over-the-counter pain relievers can help reduce fever and some symptoms

  • If severe symptoms develop, patients often need to be hospitalized for supportive treatment

  • Always speak to your healthcare provider if you suspect yourself or your family members have been infected with West Nile virus

Source: Center for Disease Control and Prevention

As the impacts of climate change manifest, the frequency and severity of West Nile Virus has the potential to greatly increase globally. The warming of the planet will likely influence global weather patterns and is especially expected to increase the intensity of rainfall around the world. This means that more flooding will occur, creating an ideal environment for mosquitos to thrive in and spreading more of the virus. Additionally, areas around the world that were previously inhospitable to mosquitos will become warmer and damper, allowing them to spread to these areas and propagate where they previously had been unable to do so. Such outcomes have already been seen in Europe during the summer of 2010, where temperatures in the spring and summer were correlated to a higher incidence of West Nile Fever throughout the continent.  

West Nile Virus is one of the thousands of diseases that have the potential to be amplified as a result of climate change. If the vector can be controlled there is a chance of reducing the incidence of disease; however, this becomes more challenging with viruses and disease-causing bacteria that transmit in other ways. Adequate measures to prevent the spread and adapt to a world where a higher incidence of West Nile will occur will be needed to prevent a widespread outbreak of the disease like the one in 1999. Furthermore, education and funding for epidemiological and public health prevention programs will be necessary to safeguard the public from the ravages of infectious diseases.