Dr. Shushila Kataria
Dengue (pronounced DENgee or DENgey) fever (also called breakbone fever) is a painful, debilitating mosquito-borne disease caused by any one of the five closely related dengue viruses (DENV 1, 2, 3, 4, and one found in 2013).These viruses are related to the viruses that cause West Nile infection and yellow fever. Dengue is spread by several species of mosquito of the Aedes type, principally, A. aegypti. They typically bite during the daytime (early morning). Humans are the primary host of the virus. Aedes aegypti prefers to lay its eggs in artificial water containers and live in close proximity to humans in order to feed on them. Dengue can be life-threatening in people with chronic diseases such as diabetes and asthma.
Symptoms usually begin four to six days after infection and last for up to 10 days. The three phases of the disease are:febrile, critical, and recovery.
1. Sudden high fever (> 104 degrees Fahrenheit); saddleback in nature, breaking and then returning for one or two days.
2. Severe headaches with pain behind the eyes.
3. Mouth, gum, nose bleeding, and easy bruisability.
4. Muscle and joint pain.
7. Rashes (that whiten on pressure) that are “islands of white in a sea of red.”
1. Hypotension (fall in blood pressure)
2. Fluid around the lungs (pleural effusion).
3. Fluid in the abdominal cavity (ascites).
4. Gastrointestinal bleeding.
1. Altered level of consciousness.
2. Seizures (fits).
4. Slow heartbeat.
The diagnosis of dengue is typically made clinically, on the basis of reported symptoms and physical examination. The earliest changes detectable on laboratory investigations are: a LOW WHITE BLOOD CELL COUNT, LOW PLATELETS, and METABOLIC ACIDOSIS.Theremay also bemoderately elevated levels of aminotransferases (AST and ALT) from the liver.
In severe disease, plasma leakage results in hemoconcentration, as indicated by a RISING HEMATOCRIT and LOW ALBUMIN.
Abdominal ultrasound is done to show FLUID IN THE ABDOMEN.
Lab tests done are:
1. VIRUS ISOLATION in cell cultures (very accurate).
2. NUCLEIC ACID DETECTION by PCR (very accurate).
3. VIRAL ANTIGEN DETECTION (such as for NS1- 90% sensitive).
4. SPECIFIC ANTIBODY ESTIMATION- IgG and IgM antibodies.
For eradication of the mosquitoes one should strengthen public health bodies and communities regarding advocacy, social mobilization, and legislation; involve health and other public and private sectors; adopt an integrated approach to disease control; target interventions appropriately; etc.
The primary method of controlling A. aegypti is by eliminating its habitat. This is done by getting rid of open sources of water, adding insecticides or biological control agents to these areas. Spraying measures help. Reducing open collections of water is preferred. Prevent mosquito bites by protective clothing, netting, applying DEET (the insect repellent).
As of December 2015, there has been no commercially available vaccine for dengue fever. The vaccine produced by Sanofi goes by the brand name Dengvaxia. It is based on a weakened combination of the yellow fever virus and each of the four dengue serotypes. Research is going on to produce a dengue vaccine to cover all four serotypes. Now that there is a fifth serotype, this will need to be factored in.
The ideal vaccine is one that should be: safe, effective after one or two injections, able to cover all serotypes, should be easily transported and stored, and should be both affordable and cost-effective.
Those patients who are able to drink, pass urine, have no “warning signs,” and are otherwise healthy can be managed at home with oral rehydration therapy; those with other health problems and who have “warning signs” should be cared for in the hospital; those with severe dengue should be admitted to the intensive care unit.
Intravenous hydration, if required, is typically only needed for one or two days. For children with shock, a rapid dose of 20mL/kg is reasonable.
Paracetamol (acetaminophen) is used for fever. NSAIDs such as ibuprofen and aspirin are avoided, as they might aggravate the risk of bleeding. Blood transfusion is initiated early in people presenting with unstable vital signs in the face of a decreasing hematocrit. Packed red blood cells or whole blood are recommended. Single donor platelet (SDP) therapy is deployed, when platelet count falls to dangerous levels.
The author is a Associate Director, Medanta Division of Internal Medicine)
Dr. Shushila Kataria