Definition: Among arthropod-borne diseases, Dengue fever is the most common. It is a disease affecting urban and peri-urban areas in tropical and subtropical regions. The rise of dengue and dengue hemorrhagic fever is attributed to increased population, urbanization, inadequate water management, travel, and trade, according to the World Health Report (1999).
In India, Dengue fever is endemic. It is widely prevalent, 217 dengue-related deaths occurred during 2003. Dengue is caused by any of the four (DEN-1, DEN-2, DEN-3, and DEN-4) serotypes of this flavivirus. It triggers 50 million worldwide infections. Dengue hemorrhagic fever and dengue shock syndrome are the most severe symptoms of dengue fever.
Epidemiology
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- Epidemiological studies have shown that secondary infection with a separate dengue serotype from the original infecting virus is the greatest risk for developing DHF or DSS. Burke, D.S et al. did this epidemiological research in Bangkok on dengue. infection in the context of a prospective analysis.
- Via the bite of an infected Aedes mosquito, the man gets a dengue virus infection. When they bite infected humans, mosquito gets infected and later spread infections to other individuals when they bite. There are two major mosquito species: Aedes Egypt and Aedes albopictus.
- A study conducted by Ekta Gupta on ‘The changing epidemiology of dengue in Delhi, India’ showed that 44.56% (811) of 1820 serum samples were received from suspected cases during the years 2003, 2004, and 2005 were reported serologically as having dengue infection. Out of these confirmed cases, the highest number of cases was 21-30 years of age.
- Dengue epidemiology in Delhi is rapidly evolving and dengue serotype 3 is now emerging as the predominant serotype. The outbreak was mostly due to the dengue 2 virus in 1996. Following this, in Delhi, dengue virus 1 activity was seen in the post endemic era of 1997. However, it was recorded that dengue-3 pre-dominated in some parts of northern India in 2003.
Agent/Factor
- Dengue fever is caused by flavivirus (DEN-I, DEN-II, DEN-2, and DEN 4) serotypes. Dengue fever is an acute viral infection and occurs in epidemic or endemic forms in India.
- After feeding on infected patients, the Aedes mosquito becomes contagious. The incubation time for the development of the Aedes mosquito infection is 3-10 days. And once the Aedes mosquito is contagious, it will remain contagious for life.
Host Factor: Dengue fever can occur among all ages and both sexes.
Environmental Factor: Rainy season when the breeding of mosquitoes is abundant and stagnant water causes the breeding of mosquitoes.
Incubation Period: 3-10 days.
Mode of Transmission: Vector-borne transmission.
Symptoms of Dengue
(A) Classical Dengue Fever: High fever with chills (39°C to 90°C), intense headache, joint pain, muscle pain, weakness, constipation, altered taste, sore throat, rashes, etc.
(B) Dengue Hemorrhagic Fever (DHF): Same symptoms as classical dengue fever and also include Damage to blood and lymph vessels and bleeding from the nose, gums.
(C) Dengue Shock Syndrome: It includes all symptoms of dengue-like; fever, bleeding, and shock.
Laboratory Diagnosis
Blood test for platelets: Platelets less than 100,000/mm³ will be in Dengue Hemorrhagic Fever.
Prevention and Control of Dengue
In the past 20 years, the prevention and control of dengue DHF have become urgent with increasing geographical spread and increasing incidence. To ensure efficient case management, community-based integrated mosquito control, and appropriate use of vaccines where available, an efficient disease prevention program must have many integrated components including successful laboratory-based surveillance, emergency response, and medical community education.
(1) Active surveillance: It is an essential component of a plan to avoid dengue. The aim should include the justification that emergency mosquito control programs can be introduced with an early warning or predictive capacity for disease transmission. Hospitals used as sentinel sites should include all patients in the community who have significant infectious diseases.
(2) Mosquito control: In and around the house, where most transmission occurs, prevention and control depend on the control of the mosquito vector. Larval source reduction in the removal or cleaning of water-holding containers that function as the domestic environment of the larva habitat is the most efficient way to manage the mosquito transmitting dengue.
(3) Community participation: The focus nowadays is on community-based approaches. To attain community engagement, preventive programs need comprehensive health education.
(4) Prevention of dengue in travelers: Effective prevention of dengue fever is difficult to achieve for travelers visiting tropical areas. But it may greatly reduce the risk of infection. Precautions include as follows:
- Staying in rooms with screening or air conditioning.
- To kill adult mosquitoes indoors, rooms are sprayed with aerosol-bound insecticides.
- Application of a DEET (dimethyl-methazolamide) repellent on bare skin.
- Wearing protective clothes.
(5) Early diagnosis and treatment: The cases of dengue should be diagnosed. The criteria given by WHO for diagnosis of dengue hemorrhagic fever is:
- Acute onset of high-grade fever continuously lasting for 2-7 days.
- Presence of any hemorrhagic manifestations such as;
- Petechae, purpura, ecchymosis.
- Haematemesis or Malena.
- Epistaxis or gum bleeding.
- Enlargement of the liver.
- All the above signs and hypotension and the appearance of cold, clammy skin, and restlessness will be there for Dengue Shock Syndrome (DSS) diagnosis.
- The treatment of dengue fever is symptomatic and supportive which includes; bed rest, antipyretics, hydrotherapy, intravenous/oral fluids, blood transfusion.
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