The news that Anthony Fauci, the longtime former director of the National Institute of Allergy and Infectious Diseases, is recovering from a severe bout of West Nile fever shines a spotlight on a disease that sickens scores of Americans every summer but receives little attention.
The mosquito-borne virus causes asymptomatic infections in most people who contract it. But about one in five infected people develop symptoms, and some of them become seriously ill, like 83-year-old Fauci. He was hospitalized for six days and said in an interview with STAT that he is now recovering and “absolutely heading in the right direction.”
Here are some facts about West Nile virus infection.
His story: West Nile virus was first discovered in the United States in 1999, when several human cases were diagnosed in New York State. It is believed that the virus entered the country either through mosquitoes travelling on airplanes or through the blood of infected people. Previously, the virus had only been detected in Africa, the Middle East, Asia and parts of Europe. Since its arrival in North America, it has spread across much of the continent.
Its life cycle: The virus is transmitted to humans by infected mosquitoes, primarily Culex mosquitoes. Infected mosquitoes bite birds and horses, which become viremic – they have the virus in their blood – and can infect more mosquitoes that feed on them. Over the summer months, this cycle causes the population of infected mosquitoes to expand, increasing the risk that infected mosquitoes will feed on them and infect humans. Most human infections occur in the late summer half, peaking in August and September. The number of human infections varies from year to year.
https://www.cdc.gov/west-nile-virus/data-maps/historic-data.html
The disease caused by this: The Centers for Disease Control and Prevention estimates that about eight in 10 people who are infected do not develop symptoms. The risk of developing WNV after infection increases with age. People over 60, as well as people with cancer, diabetes, high blood pressure, kidney disease, and organ transplant patients are at greater risk. About one in five people become ill. Symptoms include fever, chills, muscle and joint pain, headache, vomiting and diarrhea, and rash. About one in 150 people develop neurological symptoms when the virus enters the central nervous system. And about one in 10 people who become seriously ill die from the infection.
How to prevent it and how to treat it: There is no vaccine for West Nile virus, so the best way to prevent infection is to take steps to avoid mosquito bites. Eliminate standing water around your home, because mosquitoes lay their eggs in water. Use a mosquito repellent that contains DEET. There is no specific antiviral treatment for West Nile virus. If people become seriously ill, they may need to be hospitalized and treated with supportive care such as intravenous fluids and pain medication.
The numbers: The numbers don’t reflect the full infection picture because most people who contract this virus never get tested for it. Some years are worse than others in terms of the burden of WNV infection. For example, in 2003, the worst year in the U.S., nearly 10,000 cases were detected, according to the CDC. Last year, nearly 2,600 cases were reported. The CDC says it has received 216 reports of WNV infections in 33 states so far this year, as of August 20. Of those cases, 142 involved neuroinvasive disease, the most serious form of WNV fever.
Source: CDC
https://www.cdc.gov/west-nile-virus/data-maps/historic-data.html
