DENGUE FEVER Heshu Sulaiman Rahman December 2016

Definition Dengue fever is an illness caused by infection with a virus transmitted by the mosquito. Close-up of an Aedes mosquito

Alternative Names Onyong- Nyang Fever. West Nile Fever. Break Bone Fever. Dengue like Disease.

Epidemiology of the Disease First reported epidemics in 1780 in Asia, Africa, and North America. The first outbreak of dengue in India was on 1812. Tropical regions (India, Malaysia, Indonesia, Thailand, ….) are the endemic areas.

Inter Play of Three Factors Human Interaction The Virus The Mosquito

The Dengue Virus Classification Family: Flaviviridae. Genus: Flavivirus. Species: Dengue virus.

The Dengue Virus It is an arbovirus (arthropod-mosquito) born virus. Composed of single-stranded RNA. Has 4 serotypes (DEN-1, 2, 3, 4). Transmitted by mosquito.

The Dengue Virus Serotypes Each serotype provides specific lifetime immunity, and short-term cross-immunity . All serotypes can cause severe and fatal disease. There is genetic variations within serotypes. These genetic variants appear to be very virulent or have greater epidemic potential.

Dengue Virus Electron Micrograms

The Aircraft for Dengue Infected Female Urban Mosquito Aedes aegypti

Aedes aegypti Mosquito It is 5 mm in size. Lives in fresh water and stagnant water. Lays eggs preferentially in discarded containers, plastic containers, etc. Tropical regions like India, Malaysia, Indonesia are its favorite zones. Bites and catches us unaware.

The Aircraft (Aedes aegypti) The most common epidemic vector of dengue in the world is the Aedes aegypti mosquito. It can be identified by the white bands or scale patterns on its legs and thorax.

Aedes aegypti Mosquito Usually breed in stagnant water. Usually active in dark or shaded places. Distance of flight: less than 100 meter Most active: 2 hours before sunset (5-6pm) and morning (8-9am).

Dengue Transmission Cycle 1. The virus is inoculated into humans with the mosquito saliva. 2. The virus localizes and replicates in various target organs (local lymph nodes and the liver). 3. The virus is then released from these tissues and spreads through the blood to infect WBC and other lymphatic tissues. 4. The virus is then released from these tissues and circulates in the blood (viremia about 5 days).

5.The mosquito ingests blood containing the virus. 6.The virus replicates in the mosquito mid gut, the ovaries, nerve tissue and fat body. It then escapes into the body cavity, and later infects the salivary glands (8-10 days). 7.The virus replicates in the salivary glands and when the mosquito bites another human, the cycle continues.

Incubation Period of Aedes aegypti Usually mosquitoes are only infected by biting a viremic person. Then, within the mosquito, the virus replicates during an extrinsic incubation period of 8-12 days. The mosquito then bites a susceptible person and transmits the virus to him. The virus then replicates in the second person and produces symptoms at an average of 4-7 days after the mosquito bite (intrinsic incubation period).

Dengue Fever – Mode of Transmission Infected mosquito Healthy person Infected person Incubation Period: 3 to 14 days Most commonly 4 to 7 days Dengue fever is mainly transmitted to human beings through the bite of mosquitoes which are infected with a dengue virus. A healthy person gets dengue fever after being bitten by an infected mosquito. The virus enters his blood from the mosquito’s saliva. The incubation period is around 3 to 14 days, most commonly 4 to 7 days and the patient will start to have symptoms of dengue fever. An infected mosquito carries the virus for life. It also spreads the virus to its offspring through laying infected eggs. Dengue fever is only spread by mosquito bites. It is not spread by contact with infected persons. Dengue fever is not spread by contact with infected persons

Distribution in the World Prevalent from centuries Highly prevalent now

Dengue Clinical Syndrome Dengue Presentation 1. Classic dengue fever (90%). 2. Dengue hemorrhagic fever (DHF) (7%). 3. Dengue shock syndrome (DSS) is actually a severe and dangerous form of DHF (3%).

Clinical Signs Classical Dengue Fever Sudden onset of fever, headache and chills. Back pain with severe muscle and joint pains. Nausea, vomiting, metallic taste. Pain behind the eyes and on moving the eyes. Rash, with red patches or spots on the skin.

Clinical Signs Hemorrhagic Dengue Fever Abrupt change from acute fever to hypothermia. Sweating and prostration. Persistent vomiting. Hemorrhagic manifestations with severe depression. Abdominal pain and restlessness.

Clinical Signs Dengue Shock Syndrome Evidence of circulatory failure (rapid and weak pulse, narrow pulse pressure (< 20 mm Hg). Hypotension, may ends with collapse and death. Cold, clammy skin and altered mental status, frank shock. Bleeding into skin, gum, nose, mouth, GIT, hematuria and Increased menstrual flow.

Skin Bleeds

Bleeding into the Eye

Large Bleed into Skin

Bleeding Spots in Skin Normal Dengue

Rare Types of Dengue Brain damage. Liver damage. Heart damage. Severe bleeding into stomach.

Morbidity and Mortality More than 2.5 Billion people live in areas that have a risk of infection. Over 100 million cases of Dengue infection are reported each year globally. DHF has a 5% fatality rate for those infected. People at high risk are children and the elderly.

What are the Tests Needed? Routine blood test. Tests to check the clotting process. Special tests to identify the Dengue virus. Dengue antigen detection by Immunohistochemistry and Immunoflurescence. Detection of antibodies in the blood (IgM) by PCR and ELISA. Urine to check for protein leakage.

Special Test (ELISA) ELISA Plate IgM-capture ELISA

Laboratory Test Results of Dengue Disease Leucopenia. Thrombocytopenia (100,000/mm3 or less). Elevated hematocrit (20% or more over baseline). Low albumin (capillary leakage, pleural or other effusions).

Treatment of Dengue Fever There is no specific treatment. Plenty of water and salt are required with antipyretics. No vaccine available yet. Blood transfusion in patients with significant blood loss. Pain killers and sedatives should be used in serious cases.

Cautions During Treatment Avoid Aspirin (worsen hemorrhage). Steroids should not be used. Children below 12 require careful watch for dangerous form. No antibiotics are of proven value.

Child with Severe form of Dengue Oxygen IV Fluids Special Care

Common Misconceptions Severe Dengue is only a childhood illness: No, All ages may be involved. Sever form is a problem of poor families: No, the effluent do get very sick.

Can We protect Ourselves? How to prevent mosquito spread? Do not allow empty vessels, plastic containers, flower pots, tires,…. to collect rain water in them. Frequently (once in 2-3 days) empty all water storage containers. Cover your over tanks to prevent mosquitoes breeding in fresh water.

How to Prevent mosquito Bites? Screen your homes with mosquito screens (Netlon). Wear full clothing (long sleeves). Apply mosquito repellents (Odomos) Keep Dengue fever patient under mosquito net. True community participation is key.           

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