Dengue (pronounced “DENG gay”) fever is a widespread mosquito transmitted disease in the tropics of Southeast Asia, Indonesia, Africa, tropical Australia, South and Central America, and the Caribbean. Health officials estimate it affects 50,000,000 people every year. After a 75-year hiatus, dengue fever reappeared in Florida in 2009 and again in 2010.
Symptoms of Dengue Fever
As it is a viral disease, there is no cure for dengue, but people who become ill from it develop immunity to the strain that caused their illness. With four strains of the virus, an individual may become ill with dengue as many as four times until an immunity is built up against each strain.
Dengue is a member of the flavoviruses that often cause debilitating symptoms, but are rarely fatal, and patients normally recover fully after a three to four week illness. It is so debilitative that a common name for the disease is “break bone fever.” Intense symptoms appear several days (five to 12) after being bitten by a mosquito carrying the virus, last a little over a week, and the recuperation period may span two to three weeks after the primary symptoms ease.
It starts with a sudden onset, high fever (up to 104º or 105º F) and headache, accompanied by severe muscle or bone pain – often accompanied by an all-body rash of small red bumps that begin on the arms and legs, and spread to the back, abdomen, and chest. These last for one to seven days, then usually go away. A few days later, a second bout of less intense symptoms may occur.
The initial onslaught may be accompanied by enhanced sensitivity to touch, an upset in taste sensation, nausea and vomiting with loss of appetite, chills, flushed face, painful and reddened eyes, lower back pain and general weakness, swollen lymph nodes, reddened and swollen soles of the feet and palms of the hands, and complete exhaustion. Although dengue fever is rarely (~1%) fatal, about 5% of cases escalate to dengue hemorrhagic fever, which has a fatality rate approaching 30%.
After the acute symptoms go away, the patient continues to be exhausted, dehydrated, and uncomfortable for two or more weeks.
How Dengue Fever Arrived in Florida
The first recognized case of dengue fever was diagnosed by a doctor in New York in September 2009. The patient presented typical symptoms, but had only travelled to Key West in the previous months. The doctor contacted the Centers for Disease Control and the health authorities for Key West and the State of Florida. Subsequently, three other cases of non-travel related dengue fever were diagnosed in Key West with another 24 cases by the end of 2009. The original case exhibits the first step in the typical mode of insect transmitted disease invasion:
- A traveller contracts the disease in a foreign location and returns home.
For the disease to become established in a new location, there are more steps:
- An insect capable of transferring the disease organism from one individual to another must be present. (One insect capable of transferring dengue fever is the Asian tiger mosquito, Aedes albopictus. This mosquito lives in the five boroughs of New York City and adjacent metropolitan areas.)
- The insect has to bite the infected traveller and subsequently other people to spread the disease.
This is the scenario that produced an outbreak of chikungunya in Italy in 2007 and an outbreak of dengue fever in Hawaii in 2001.
How Prevalent is Dengue Fever
Most people becoming infected with dengue fever barely notice the illness. Key West has a population of 25,000. Twenty seven people (0.1%) were diagnosed with dengue fever in 2009 and several more in 2010. By sampling 240 people, the Centers for Disease Control (CDC) estimated that almost 5% of the population would test positive for recent production of antibodies for dengue fever – and an additional 41% were exposed to dengue fever earlier in their lives. Less than 3% of the more than 1000 people expected to show recent antibody production were diagnosed with dengue fever. According to CDC, the 41% of the population that had been exposed to dengue fever previously suggests that dengue fever has been in Key West for some time, but those affected did not present the characteristic serious symptoms of the disease and it went unrecognized.
Most people suffering from dengue fever have mildly to severely weakened immune systems. Children, people with previous viral or bacterial infections, and older people exhibit the most severe symptoms as do people becoming infected with a second strain of dengue stand the greatest risk of suffering severe episode of the disease.
Page 2: Transmission, Treatment, and Prevention of Dengue Fever
Albert Burchsted - Ph.D. in animal behavior, field biologist, and photographer. Al leads nature study walks and is an environmental consult in SE ...
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