Overview on Dengue: Causes, Symptoms, Prevention and Treatment

Dengue is endemic in India. For the past ten years, the number of dengue cases has gradually increased in India. Transmission occurs year-round in southern states and from April through November in northern & eastern states. Recent cases have been reported in several Indian states including Andhra Pradesh, Assam, Bihar, Delhi, Goa, Gujarat, Haryana, Jharkhand, Karnataka, Kashmir, Kerala, Maharashtra, Odisha, Puducherry, Punjab, Rajasthan, Tamil Nadu, Telangana, Uttarakhand, Uttar Pradesh, and West Bengal. In this post, we will look into an overview of dengue including a brief history and the causes. More importantly, we will discuss the dengue symptoms, prevention, and treatment.

Introduction

Dengue
Aedes aegypti (Source: Cosmos Magazine)

Dengue is a mosquito-borne viral disease. It is driven by complex interactions among host, vector, and the virus that are influenced by climatic factors. Dengue has been spreading among the population of the world at a very larger pace. In the last 50 years, the deadly disease has increased spreading rapidly.

Dengue is not only affecting the large cities of the globe but also the semi-urban areas, rural areas and even the remotest part of many countries. It deserves to be mentioned that the semi-urban and rural areas are starting to get affected in the present decade.

An estimated 390 million dengue infections occur worldwide each year, with about 96 million resulting in illness. Most cases occur in tropical areas of the world, with the greatest risk occurring in:

  • The Indian subcontinent
  • Southeast Asia
  • Southern China
  • Taiwan
  • The Pacific Islands
  • The Caribbean (except Cuba and the Cayman Islands)
  • Mexico
  • Africa
  • Central and South America (except Chile, Paraguay, and Argentina)

Dengue in India

Dengue in India
(A) Mean annual rainfall (mm) based on the TRMM satellite data and (B) mean (C) minimum and (D) maximum temperature (°C) based on the NCEP2 reanalysis data set. The annual mean is calculated for the 1998–2014 period. This figure was created using the National Centre for Atmospheric Research (NCAR) Command Language (NCL) version 6.1.2 (http://www.ncl.ucar.edu/). [Source: Nature]

History of Dengue Fever

An epidemic occurred between 1779 and 1780 affecting Asia, Africa & North America. This is the most authentic early report of the dengue epidemic. It was in the year 1946 when dengue first appeared in India. After that, some of the regions of India like Vishakapatnam in 1969 and Jalore, Rajasthan in 1985 have got affected by this virus on a small scale. The first visit of this disease in India was in the year 1964 and Delhi was hit by a serious outbreak in the year 1996. During Oct-Nov 2005, some reports of unknown fever were emerging in Siliguri and Darjeeling. The subsequent investigation to that areas confirmed that it is the killer virus dengue which is causing that mysterious fever.

Causes of Dengue Fever

Carrier Mosquito

The carrier of dengue virus is a mosquito named Aedes aegypti. When an Aedes mosquito infected with this virus bites a human he or she will also get infected by this virus. This mosquito has a wide distribution throughout the world and chiefly exists in the tropical and subtropical regions of the earth.

Transmission of Dengue Virus

This virus is propagated & transmitted mainly by humans who serve as a host for this virus. The female Aedes mosquito feeds on human blood and during feeding, it ingests dengue virus which is circulating on the blood of the infected human.

The virus then infects the mosquito mid-gut and reproduces in a systematic manner for a period of 8 to 12 days. After this incubation period is over the virus get transmitted to other uninfected humans at the time of subsequent feeding. The ambient temperature plays a crucial role during the incubation period.

Next, the mosquito remains infected by this virus for the rest of its lifespan. This mosquito is particularly efficient because it is anthropophilic and survives in close contact with the humans.

Causes of Spreading of Dengue Virus

India is currently witnessing a rapid urbanization. Massive scale construction projects are taking place not only in cities but also in semi-urban areas which are providing sufficient breeding grounds for the female Aedes aegypti mosquito which is the vector of dengue virus.

This mosquito breeds in clean stagnated water. Water remains accumulated or stagnated for days in different construction sites thus helping the mosquito to reproduce and increase in number. According to the West Bengal State Government reports, 40 people have lost their lives due to dengue and at least 20,500 people have been diagnosed with this disease in 2017.

Eminent virologist and former head of parasitology department Dr. Amitava Nandi have thrown some light in another cause of the unnatural rise of dengue cases in Kolkata. He stated that due to extensive urbanization the social lives of the people of West Bengal have changed drastically. This urbanization has led to the increased use of artificial plastic containers in the city.

Dengue in Kolkata
Source: Times of India

In earlier days products were sold in paper bags but due to changed lifestyle products are now sold in plastic bags and containers thereby providing more breeding space for the Aedes mosquito. Water remains accumulated in those plastic containers during raining which helps the larvae to thrive and reproduce. He also mentioned that as these plastic containers are used in semi-urban and rural areas helping to increase the mosquito population, so those areas are also affected by the dengue virus.

In this context, it should be mentioned that proper drainage system is not provided to those buildings which were constructed in an unplanned manner which have played role in the excessive increase of mosquito population thereby increasing dengue cases.

Dengue Symptoms

dengue symptoms
Source: Ayurveda and Yoga

Dengue symptoms usually begin 4 to 6 days after infection. The symptoms last for up to 10 days. Typical dengue symptoms are:

  • Sudden high fever
  • Severe headaches
  • Pain behind the eyes
  • Severe joint and muscle pain
  • Fatigue
  • Nausea
  • Vomiting
  • Skin rash, which appears two to five days after the onset of fever
  • Mild bleeding (such as a nose-bleed, bleeding gums, or easy bruising)
Dengue Symptoms
Source: Medyhealth

Sometimes, symptoms are mild and can be mistaken for those of the flu or another viral infection. Younger children and people who have never had the infection before tend to have milder cases than older children and adults. However, serious problems can develop. These include dengue hemorrhagic fever, a rare complication characterized by high fever, damage to lymph and blood vessels, bleeding from the nose and gums, enlargement of the liver, and failure of the circulatory system. The symptoms may progress to massive bleeding, shock, and death. This is called dengue shock syndrome (DSS).

Diagnosis of Dengue

Dengue infection can be diagnosed by a blood test. A number of tests are available to confirm the diagnosis including detecting antibodies to the virus or its RNA. If you become sick after traveling to a tropical area, let your doctor know. This will allow your doctor to evaluate the possibility that your symptoms were caused by a dengue infection.

Dengue Treatment

According to the version of experts, neither any medical treatment nor any antibiotic is available for curing dengue. Only supportive treatment or therapy can be provided to the patients giving them a chance to fight the virus with the help of immunity of their own body and recover.

If you think you may have dengue fever, you should use pain relievers with acetaminophen and avoid medicines with aspirin, which could worsen bleeding. You should also rest, drink plenty of fluids, and see your doctor. If you start to feel worse in the first 24 hours after your fever goes down, you should get to a hospital immediately to be checked for complications.

dengue treatment
Source: City Pass Guide

Immediate hospitalization is required if dengue is detected. In the hospital, normal saline is administered to the patient’s body. Paracetamol (not more than 4 times in 24 hours) is given to the patients regularly until the fever subsides.

Dengue Prevention

In terms of preventive measures, public awareness is the main thing by which dengue can be prevented. It should be informed to all the public not to use plastic containers or throwing them in the streets and also asking them not to accumulate water in open containers. Mosquito-proofing of the water storage containers can be done for enhanced protection.

Change of human habits like using mosquito nets during sleeping, installing mosquito nets on the window can help prevent dengue. Dispose solid wastes properly and do the cleaning of streets on a regular basis.

dengue prevention

In terms of chemical control larvicides which are colorless, odorless and are non-toxic can be applied to the clean drinking water in order to kill the larvae of Aedes mosquito. Guppy (Poecilia reticulata) fish can be harvested in the ponds which feed on mosquito larvae.

The dengue mosquito typically attacks during the day and some experts say the favorite spots are below the elbow and below the knee. They are most active between the time period of August-October and do not breed when the temperature falls.

Dark colors attract mosquitoes. So, avoid wearing dark and tight clothing. Doctors and physicians recommend loose, white and long clothes, which cover the whole body. Mosquitoes find it difficult to bite through loose clothes than tight-fitting clothes.

The worst hit age group has been school and college children. An effective implementation of wearing full-sleeved clothes policy can bring down the number of cases by up to 50%.

Try reducing the mosquito habitat by removing standing water around your house. You could turn to natural repellents like Lemon Eucalyptus Oil, Lavender, Neem Oil and Cinnamon Oil to protect yourself against mosquito bites.

There are a number of plants that have mosquito repellent properties like feverfew, citronella, catnip, and lavender. Place them around your house to keep mosquitoes away. Even herbs like garlic, lemongrass, basil, peppermint, rosemary may help.

Quick tips on Dengue Prevention:

  • Stay away from heavily populated residential areas, if possible.
  • Use mosquito repellents, even indoors.
  • When outdoors, wear long-sleeved shirts and long pants tucked into socks.
  • When indoors, use air conditioning if available.
  • Use a repellent containing 20%-30% DEET or 20% Picaridin on exposed skin. Re-apply according to manufacturer’s directions.
  • Wear neutral-coloured (beige, light grey) clothing. If possible, wear long-sleeved, breathable garments.
  • If available, pre-soak or spray outer layer clothing and gear with permethrin.
  • Get rid of water containers around dwellings and ensure that door and window screens work properly.
  • Apply sunscreen first followed by the repellent (preferably 20 minutes later).
  • More details on insect bite prevention.

Special Tips for Babies & Children

an adult male applying insect repellent to a child's face

  • Always follow instructions when applying insect repellent to children.
  • Do not use insect repellent on babies younger than 2 months old.
  • Do not apply an insect repellent onto a child’s hands, eyes, mouth, and cut or irritated skin.
  • Adults: Spray insect repellent onto your hands and then apply to a child’s face.
  • Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.

Home Remedies for Dengue Prevention

Giloy: Giloy is a very important herb in Ayurveda. It helps in maintaining the metabolic rate, strengthening the immune system and protects your body against infections

Papaya Leaves and Pomegranates: They help in increasing the platelet count and reduces the symptoms of fever like body ache, chills, feeling low, getting tired easily and nausea.

Methi Leaves: Methi leaves reduce fever and act as a sedative to ease pain and promote more restful sleep for patients.

Turmeric:  Turmeric boosts metabolism and helps in making the healing process faster. You can consume turmeric along with milk.

Tulsi Leaves and Black Pepper: Consume a drink made by boiling Tulsi leaves and adding about 2 grams of black pepper to it. This drink helps in building your immunity and acts as an antibacterial element.

Home Remedies for Dengue
Source: Live A Little Longer

Special Precaution for Dengue in 2018

For the last few years, the nature of dengue virus has changed i.e. from Dengue-1 and Dengue-3 to new type Dengue-2 and Dengue-4. The people of West Bengal did have immunity against Den-1 & 3 which helped them to recover from the disease last year. But they do not have any biological immunity against Den-2 & 4 thus making it nearly impossible for them to survive this year. Hence the State Government must take all the necessary steps to arrest the breeding of mosquito in the first place.

Acknowledgment: This article has been co-authored by Sujoy Sengupta

Sources: 1, 2, 3, 4, 5, 6, 7, 8, 9.

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