In recent years, West Nile virus is what led most of us to be aware mosquitoes are more than just irritating, buzzing pests. We’ve become accustomed to using repellent and to Health Department alerts about positive West Nile mosquito pools.
Through the years I’ve given plenty of ink to West Nile, from when the first U.S. cases were detected in 1999 in New York to subsequent cases and deaths locally.
Now a different mosquito-borne virus, dengue fever, is raising concerns among U.S. public health officials because for the first time in this country in nearly 60 years dengue fever is on the rise. Sometimes referred to as break-bone fever, dengue’s hallmark symptoms are high fever, severe bone and joint pain and headache. (For a more complete symptom list see fact box.)
Early this month, the Florida Department of Health reported at least 24 new cases in people who had not traveled outside the United States. Until now, confirmed U.S. cases since the 1940s were in individuals who acquired the disease while in another country.
Officials with the Centers for Disease Control and Prevention have issued reports about the recent Florida cases and acknowledge concerns the virus will spread north. In April, Allen County Commissioner of Health Dr. Deborah McMahan sent an advisory to area physicians that dengue fever had been diagnosed in a number of U.S. relief workers who had traveled to Haiti to assist with post-earthquake relief work.
McMahan said late last week she planned to send another memo to doctors by today, reminding them to be on the lookout for West Nile or dengue in symptomatic people.
The disease, which is caused by one of four different viruses, is spread when a mosquito bites an infected person and then carries the virus to another person.
Public health experts say the disease is coming into this country when people get bitten and infected while visiting another country. They may not have symptoms until after they return home or, in some cases, they may not develop symptoms. Mosquitoes here then bite those individuals and the disease is spread when they bite new people. Experts say it also is likely infected mosquitoes are coming into the country via airplanes and cruise ships.(See sidebar about one teen’s experience with dengue fever.)
Dengue fever is now the No. 1 mosquito-borne disease, causing an estimated 100 million human cases worldwide each year. According to the World Health Organization, the number of cases reported yearly has more than doubled since 1990.
Retired Fort Wayne physician Dr. Ian Cook travels annually to the Dominican Republic for medical mission work. When he was there last year, he and his missionary colleagues noticed native doctors and staff using mosquito netting. They assumed it was to prevent malaria, another very common tropical disease.
“But they told us malaria is not much of a problem there. The locals use mosquito nets because of dengue fever. That is the bigger concern,” said Cook, who is preparing to return to the Dominican in October.
No one is yet sounding the alarm in this country about dengue fever, but we should not ignore the fact one in every 50 deaths worldwide is due to an insect bite, according to the WHO.
Thus an alarm has been sounded by public health and infectious disease organizations over President Obama’s proposed 2011 budget, in which 100 percent of funding would be cut for the CDC’s surveillance and outbreak control programs of vector-borne disease such as dengue, West Nile, LaCrosse encephalitis and Lyme disease.
Just over a decade ago, most Hoosiers had never heard of West Nile virus. Its very name suggested it was a disease that would only affect people in some distant county.
But in today’s world, we have global communications and global diseases, the WHO’s DengueNet website reminds us, pointing out, “International air travel is facilitating the rapid global movement of the viruses that cause dengue …” and other mosquito-borne diseases.
It behooves us to remain vigilant about preventing mosquito bites — and for the federal government to retain funding for surveillance programs for diseases we once thought would never return or come to this country in the first place.
Dengue details
♦Four distinct types of dengue fever (DF) occur; infection with one does not make you immune from infection with another.
♦In addition to high fever, dengue causes any or all of these symptoms: bone and joint pain; severe headache; pain behind the eyes; chills; bleeding gums or nose; and easy bruising.
Symptoms of infection usually begin four to seven days after the mosquito bite and last three to 10 days.
♦Dengue hemorrhagic fever (DHF) is a more serious form of the disease. Small blood vessels leak, and respiratory and circulatory failure cause shock and risk of death.
♦Younger children and individuals with their first DF infection have a milder illness, in most cases, than older children and adults. Subsequent infections carry higher risk for DHF, which causes 200,000 deaths worldwide annually.
♦At least two types of aedes mosquitoes that carry DF are common in the United States.
♦No preventive vaccine or specific treatment for DF or DHF exists.
Source: cdc.gov