Dengue Fever Incubation Period, can be very critical! Because Dengue is an acute febrile illness caused by infection with any of four related positive-sense, dengue viruses (DENV) 1, 2, 3, or 4. Transmission happens through the bite of infected Aedes mosquitoes, chiefly Aedes aegypti and Aedes albopictus. Since dengue fever incubation period is approximately 7-day viremia, bloodborne transmission is possibly through exposure to infected blood, organs, or other tissues. Besides, when perinatal DENV transmission occurs, the highest risk seems to be among infants whose mothers are ill around the time of delivery. DENV can also be transmitted through breast milk.
Dengue is an epidemic throughout the tropics and subtropics and is a primary cause of febrile illness among travelers from Latin America, Africa, Southeast Asia, and the Caribbean. Dengue occurs in more than 100 countries worldwide, including Brazil, Puerto Rico, Venezuela, the US Virgin Islands, and US-affiliated Pacific Islands. Even though the geographic distribution of dengue is alike to that of malaria, dengue is a bigger risk in urban and residential regions than malaria. DengueMap presents up-to-date information on areas of ongoing transmission.
Almost 75% of all DENV cases are asymptomatic. Symptoms often present as a mild to acute, febrile, moderate, and nonspecific illness. However, 5% of all dengue patients manifest a severe, life-threatening disease. Early recognizing signs of shock and instantly initiating proper supportive therapy can reduce the risk of death among severe dengue patients from 10% to less than 1%.
Dengue begins suddenly after an incubation period of 5–7 days and the course follows three phases: febrile, critical, and convalescent. Fever lasts 2–7 days and could be biphasic. Other signs and symptoms include:
- retroorbital pain
- severe headache
- macular or maculopapular rash
- muscle, joint, and bone pain
- minor hemorrhagic manifestations, such as bleeding gums, ecchymosis, epistaxis, hematuria, purpura, petechiae, or a positive tourniquet test result.
Warning signs of progression to severe dengue include:
- difficulty breathing
- mucosal bleeding
- severe abdominal pain
- persistent vomiting
- signs of hypovolemic shock
- the rapid decline in platelet count along with an increase in hematocrit (hemoconcentration)
Clinical Presentation for Patients with severe plasma leakage
Patients with severe plasma leakage suffer plural effusions or ascites, hemoconcentration, and hypoproteinemia. They may appear to be well in spite of early signs of shock. Once hypotension develops, however, systolic blood pressure will decline, and irreversible shock and death may proceed despite resuscitation. Patients may also present severe hemorrhagic manifestations, including bloody stool, hematemesis, melena, or menorrhagia, particularly if they have prolonged shock. Atypical manifestations involve encephalitis, hepatitis, myocarditis, and pancreatitis.
Data are incomplete for outcomes of dengue in pregnancy and impacts of maternal dengue infection on the developing fetus. Perinatal transmission may occur and increase the potential for symptomatic infection in the newborns. Of the 34 perinatal transfer cases, all developed thrombocytopenia and had a fever in the first two weeks after birth. Nearly 40% presented a hemorrhagic manifestation, and one-fourth suffered hypotension. Placental transmission of maternal IgG anti-DENV can increase the risk of severe dengue among babies infected at 6–12 months of age, especially when the protective effect of these antibodies decreases.
Guidelines for Classifying Dengue
Symptomatic cases of dengue or severe dengue are classified by a guideline issued by the World Health Organization (WHO) in November 2009. Dengue is defined by a combination of more than two clinical findings in a febrile person who lives in or travels to a dengue-endemic area. These clinical findings include vomiting, rash, nausea, aches and pains, leukopenia, a positive tourniquet test, and the following warning signs: persistent vomiting, lethargy, restlessness, mucosal bleeding, clinical fluid accumulation, abdominal pain or tenderness, and liver enlargement.
Severe dengue is classified by any of the following symptoms: severe bleeding; severe plasma leakage causing shock or fluid accumulation with respiratory distress; or severe organ impairment e.g. elevated transaminases ≥1,000 IU/L, heart impairment, or impaired consciousness.
Clinicians should look for dengue in a patient who has returned from an endemic area within two weeks before symptom onset. All suspected cases must be reported to the local health department since dengue is a worldwide reportable disease. Laboratory confirmation can be conducted by detecting DENV genomic sequences with RT-PCR or by identifying DENV nonstructural protein 1 (NS1) antigen by immunoassay. Four days after fever onset, ELISA can detect IgM anti-DENV. Diagnostic testing should involve a test for DENV and IgM anti-DENV. For patients presenting more than one week after fever onset, IgM anti-DENV is most useful although NS1 has been recognized positive up to 12 days after fever onset.
No specific cure exists for dengue. Patients should stay well hydrated and avoid aspirin and other nonsteroidal anti-inflammatory drugs (e.g. ibuprofen) since they increase the risk of internal bleeding. Control fever with acetaminophen, paracetamol, and tepid sponge baths. Patients need to avoid mosquito bites to lessen the risk of further transmission. For those who manifest severe dengue or other complications, close observation and monitoring in an intensive care center are compulsory. Prophylactic platelet transfusions are not beneficial and may lead to fluid overload.
Up to now, no chemoprophylaxis can prevent dengue. No vaccine is available though several are in clinical trials. Travelers to endemic areas are at risk of contracting dengue; risk increases with long duration of travel and possible disease incidence in the destination (such as during epidemics or the rainy season). Dengue fever incubation period lasts for 3-10 days. Travelers going to the tropics are advised to avoid mosquito bites by carrying out the following preventive measures:
- Sleep under bed nets.
- Use insect repellents following instructions on the label.
- Wear clothing that covers the arms and legs or exposed skin, especially during the early morning and late afternoon, when Aedes mosquitoes are most active.
- Select accommodations with air conditioning or well-screened doors and windows if possible. Aedes mosquitoes tend to live indoors and in dark, cool places, such as under beds, behind curtains, in closets, in bathrooms, and on balconies. Use insecticides to destroy mosquitoes in these areas.
- Empty, clean or cover any standing water that mosquitoes can live and breed (such as water storage tanks, buckets, bottles, old tires, flower vases, etc.)
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