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Dengue Fever (cont.)

Is Dengue Fever Contagious?

Dengue fever is not contagious; it is not spread from person to person. Dengue fever viruses require a vector, a mosquito (see Causes section below), that allows the virus to mature within the mosquito before the mosquito can effectively transfer the viruses to humans during a blood meal.

How Long Is the Incubation Period for Dengue Fever, and How Long Does Dengue Fever Last?

Symptoms of infection usually start about four to 15 days (the incubation period is typically four to seven days) after a mosquito bite transfers the viruses to the human. In most instances, the disease lasts about three to 10 days, although a few patients' symptoms may last longer. During the incubation period, large amounts of the virus are present in the person's blood just before the person becomes symptomatic; this is when a mosquito that may be uninfected can pick up viruses that can be transferred to other humans. However, the virus has to develop within the mosquito for a few days before it is ready to be transferred during the blood meal (mosquito bite).

How Do Health Care Professionals Diagnose Dengue Fever?

Dengue fever is presumptively diagnosed by a medical caregiver by the relatively characteristic sequence of high fever, rash appearance, and other symptoms in a person who has a history of recent travel to dengue endemic areas and recalls mosquito bites while in the endemic area. However, if not all of the symptoms are present or the history is not complete, the caregiver is likely to run a number of tests to obtain a definitive diagnosis. Other diseases may yield similar symptoms (for example, leptospirosis, typhoid fever, yellow fever, scarlet fever, Rocky Mountain spotted fever, meningococcemia, malaria, chikungunya, food poisoning, and several others). If the patient has severe symptoms; or if the medical caregiver does not have enough information to make a presumptive diagnosis, the patient is likely to undergo a number of other tests to definitively distinguish dengue fever from other diseases. In general, the more serious the symptoms such as easy bruising, fevers at or above 104 F, hemorrhages or shock syndrome, the more tests are likely to be done.

In general, most physicians will order a complete blood test (CBC), with a metabolic panel, along with coagulation studies in most patients with high fever and any bleeding problems. Low platelet and low white cell counts may occur with the disease. In addition, depending on the symptoms (especially headache), blood and urine cultures plus a spinal tap may be done to help differentiate between dengue fever and other diseases. A MAC-ELISA assay (an immunoglobulin M-based test) is the most widely used test for dengue fever virus. However, other tests are available; they also are based on the person's immunological response to the dengue viruses (for example, IgG-ELISA, dengue viral plaque reduction tests, and PCR tests). These tests are considered definitive for exposure to dengue virus; definitive diagnosis of dengue fever is isolation and identification (usually by immunological tests) of the dengue virus serovar from the patient.

Medically Reviewed by a Doctor on 8/31/2017

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