In 2023, Colorado experienced a severe outbreak of West Nile virus, with the highest number of deaths in over two decades. However, in 2024, the state is witnessing a significant decline in mosquito activity and no human cases or deaths have been reported so far.

According to Chris Roundy, the medical entomologist with the Colorado Department of Public Health and Environment, the current mosquito activity is either normal or below normal, which is a positive sign compared to the previous year. The abundance of standing water caused by a big snowpack and a wet spring in 2023 had provided ideal breeding grounds for mosquitoes, leading to the widespread transmission of the virus.

While West Nile virus cases usually emerge between summer and fall, the risk of infection is higher for those who work or engage in outdoor activities due to increased exposure to mosquitoes. The transmission of the virus depends on various factors, including the introduction of the virus through migratory birds and the subsequent feeding of mosquitoes on both the birds and humans.

Dr. Michelle Barron, senior medical director of infection prevention and control for UCHealth, emphasized the importance of taking West Nile virus seriously. Symptoms of the virus include fever, headache, body aches, vomiting, diarrhea, and rash. While there is no specific treatment for the disease in humans, the majority of infected individuals do not experience any symptoms. However, approximately 1 in 5 infected people develop a fever and other symptoms, with 1 in 150 individuals facing serious or even fatal illness. Older individuals and those with underlying immune issues are particularly vulnerable to the virus.

Prevention is key in combating the spread of West Nile virus. Mosquitoes tend to be most active during dawn, dusk, and cooler temperatures. It is advised to wear long sleeves, pants, and use insect repellent during these periods. Additionally, removing sources of standing water from yards is crucial as these serve as breeding grounds for mosquitoes.

Ken Nordstrom, director of environmental health at the Delta County Health Department, highlights the impact of climate change on the spread of West Nile virus. As the planet warms, vector-borne diseases are expanding their geographic range, leading to increased transmission risks. The virus also replicates more rapidly in mosquitoes as temperatures rise, resulting in a higher concentration of virus in the insects.

While Colorado currently observes a decrease in West Nile virus activity compared to the previous year, officials continue to monitor the situation closely. It is essential for individuals to remain vigilant, take necessary preventive measures, and consult a healthcare provider if they suspect they have contracted the virus.

As the changing climate continues to influence the spread of diseases, it is crucial for authorities and communities to respond proactively to mitigate the risks associated with mosquito-borne illnesses like West Nile virus.