About the Predisposing Factors of Dengue
According to the Centers for Disease Control and Prevention, more than 80% of those infected with dengue virus will silently transmit the disease without symptoms or only mild undifferentiated illness. However, there is a 5% risk of death for those unfortunate patients developing dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). Numerous factors predispose patients to more severe forms of dengue infection.
Features
Dengue virus transmits primarily through bites from Aedes aegypti mosquitoes, although Aedes albopictus is also a vector in the Americas. After transmission through a mosquito bite, dengue virus incubates for three to fourteen days. Dengue then causes flu-like aches and pains, high fever, loss of appetite, headache and rash. Vascular permeability and circulatory failure characterize the most severe forms of dengue infection.
Significance
Dengue virus causes illness in up to 100 million people worldwide each year. Most of these cases manifest as dengue fever, an acute self-limited febrile condition. Of these dengue fever cases, hundreds of thousands develop into life-threatening dengue hemorrhagic fever (DHF). While mosquito eradication efforts in the 1960s essentially eliminated dengue outbreaks in the United States, between one hundred and two hundred cases of dengue appear in American hospitals each year. Dengue patients present with travel histories in dengue endemic regions less than two weeks prior to illness.
Geography
Dengue virus is endemic to tropical regions throughout the world with epidemic peaks during rainy seasons favoring mosquito reproduction. The regions of greatest risk are Southeast Asia, the Caribbean, and Central and South America. Dengue virus is also endemic to Africa, India, the Middle East and tropical islands in the Pacific.
Considerations
Based on data from Cuba, Caucasians may be at greater risk than blacks for dengue hemorrhagic fever.
Patients with a history of prior dengue infection are at higher risk of complications from severe forms of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS).
Infants with maternal antibody protection may experience only a mild undifferentiated febrile condition when infected with the same serotype. However, maternal antibodies place infants at greater risk of complications from infection with other serotypes.
Age is a risk factor. Most fatalities occur in children under age 15.
Gender is also a risk factor for severe complications. Women and young females tend to develop severe forms of dengue fever at higher rates than males.
A particularly virulent circulating strain can predispose dengue patients to severe infections.
Co-infection with multiple serotypes increases risk of morbidity and mortality. Co-infection occurs in endemic areas with multiple dengue types circulating at high frequency. This is termed hyperendemic transmission.
Prevention/Solution
There is currently no commercially available dengue vaccine. Because any dengue vaccine needs to induce immunity to four separate serotypes, creation of a safe, economical vaccine remains a challenge. An attenuated tetravalent vaccine covering all four serotypes is in field-testing but will not be available in the near future.
There is no treatment for dengue fever beyond hydration and pain relief. Preventing infection is the best way to avoid the risks of dengue fever.
Plan travel to endemic regions during the dry season.
Apply DEET mosquito repellents to clothing during the day when visiting areas of dengue endemicity.
Mosquito bed netting also helps, but Aedes aegypti feeds primarily during daylight hours. Netting of dengue patient beds reduces disease transmission.
Drain water from all mosquito breeding sites including planters, old tires, and discarded containers. Use larvicides in other water sources. Place lids on all water storage containers. Consider placing mosquito-eating fish in decorative ponds.
Locales experiencing a dengue fever epidemic may conduct aerial or ground fumigation to reduce adult mosquito populations. These methods have a limited ability to penetrate microhabitats in building interiors. Consider fumigation of residences during an outbreak.
Tags: dengue fever, dengue hemorrhagic, dengue hemorrhagic fever, forms dengue, hemorrhagic fever