What is Dengue Fever?
Dengue fever is a mosquito-borne illness spread by the Aedes aegypti or Aedes albopictus mosquito. There are four serotypes of the dengue virus, namely DENV-1, DENV-2, DENV-3, and DENV-4. Once infected with dengue, the body creates immunity towards that particular serotype for the rest of its life. As a result, a person can get infected with a dengue virus as many as four times in their lifetime. According to the United States Centers for Disease Control and Prevention (CDC), half of the world’s population lives in areas where dengue mosquitoes thrive. As a result, nearly 100 million people get infected with dengue fever every year, and almost 40000 deaths are recorded.
Which geographical regions in the world have a high risk of dengue fever?
The tropical regions across the globe are heavily affected by dengue. The tropical areas that have the most significant risk of dengue are:
- Mexico
- Pacific Islands
- The Caribbean
- South America
- Central America
- Southeast Asia
- Southern China
- Taiwan
- Northern parts of Australia
What is an Aedes aegypti mosquito?
Aedes aegypti, which is also known as the yellow fever mosquito, is a mosquito that can spread diseases like dengue fever, zika fever, chikungunya, mayaro, and yellow fever. The Aedes aegypti mosquito primarily bites aggressively in the morning (mainly active for two hours after sunrise) and at sunset. However, it can also bite at other times of the day. The physical appearance of the Aedes aegypti mosquito is a black body with a silver-white pattern of scales and banded legs. The silver-white designs look like an ancient Greek musical instrument called the lyre. The entire life cycle stage, i.e., egg-to-larva-to-pupa-to-adult for an Aedes aegypti mosquito, occurs in as little as 7-8 days. The life span for adult mosquitoes is around three weeks. The female Aedes aegypti mosquito is responsible for the transmission of Dengue.
What are the symptoms of Dengue Fever?
The symptoms of Dengue Fever begin four to ten days after an infected mosquito bites a healthy person.
A person with dengue fever passes through three stages:
Phase 1 (The Febrile Phase)
A healthy person (children and adults) who never had dengue may experience mild symptoms that last for two days to a week during the febrile phase.
The symptoms observed during the febrile phase include:
- Myalgia
- Pain in the bone or joints
- High fever ( around 1040F)
- Pain behind the eyes
- Severe headache
- Skin Rash (observed two to five days after infection)
- Swollen lymph glands
- Minor hemorrhagic manifestations like purpura, epistaxis, bleeding gums, hematuria.
- A positive result of the tourniquet test.
Phase 2 (The Critical Phase or the Immune Phase)
Generally, people recover from dengue within two days to a week. However, some people do not heal within a week, and their symptoms worsen, leading to severe dengue. This is the critical phase, and it may lead to life-threatening situations. Severe dengue is also called dengue hemorrhagic fever or dengue shock syndrome. Also, if healthy people take the Dengvaxia vaccine, they face the consequences of severe dengue. The symptoms of severe dengue include:
- Severe pain in the stomach
- Bleeding from the gums and nose
- Presence of blood in the urine, stools, or vomit
- Difficulty in breathing or rapid breathing
- Irritability
- Fatigue
- Persistent vomiting ( a person will vomit three times or more in 24 hours)
A dengue shock during the critical phase may lead to a rapid decline in systolic blood pressure (hypotension) that leads to an irreversible shock and death.
Phase 3 (The Convalescent Phase)
This is the end phase of dengue fever. The symptoms of the convalescent phase include:
- In addition, the well-being of the patient improves.
- Laboratory findings include leukopenia, thrombocytopenia, hyponatremia, elevated aspartate aminotransferase, alanine aminotransferase, and a normal erythrocyte sedimentation rate.
- Extravasated intravenous fluids and pleural and abdominal effusions get reabsorbed.
- Stability in the hemodynamic status
- A rise in the count of WBC and platelets
What are the risk factors for Dengue Fever?
The risk factors for dengue fever are:
- Traveling to or living in the dengue-endemic regions of the world.
- Presence of broken cans, earthen pots, old tyres, and other water-holding containers as garbage around the house. Rainwater or water from drainage, when it gets collected in such garbage dumps, they become the breeding place for mosquitoes.
- Females are at high risk of getting severe dengue than males.
- High Body Mass Index, Polymorphism in specific genes, and Viral Load are risk factors for severe dengue.
- G6PD deficiency disease in patients is also a high-risk factor for getting severe dengue.
What are the health complications of Dengue Fever?
Health complications related to the dengue virus is rare but may include:
- Injury to the liver ( Hepatic Injury)
- Pneumonia
- Neuromuscular complications like myalgia, myositis, hypokalemic paralysis, Guillain-Barre syndrome, and Rhabdomyolysis.
- Depression
- Cardiomyopathy
- Iritis (inflammation of the iris)
- Orchitis ( inflammation of one or more testicles)
- Oophoritis ( ovary or egg sac inflammation)
- Post-infectious fatigue syndrome
What should a patient eat if they have dengue?
Food items rich in protein and iron help the body to recover from dengue fever. The list of foods that help against dengue fever include:
- Mutton liver
- Lean meat such as chicken, fish, and lean meat
- Egg
- Milk, cottage cheese, and other Dairy products
- Coconut water
- Green vegetables, mainly green peas, chickpeas, and lentils
- Food abundant in Vitamin C like oranges, kiwis, and pineapple
- Some people also make papaya leaves juice and drink it with water on an empty stomach early morning.
Patients should avoid the following food if they have dengue or if they are recovering from dengue:
- Fruits include plum, cherry, blackberry, apple, melon, nectarine, peach, grape, tangerine, lemon, strawberry, and gooseberry.
- Dry fruits such as raisins, almonds, and walnuts.
- Green vegetables like Potato, onion, cucumber, tomato, apricot.
- Spices like pepper, garlic, and ginger.
What is Post-Infectious Fatigue Syndrome?
A patient recovering from an acute infection like dengue suffers from persisting fatigue and disability after the infection. This is called Post-Infectious Fatigue Syndrome. The mechanism behind dengue causing post-infectious fatigue syndrome is still under research. However, researchers believe that the post-infectious fatigue syndrome results from the alterations in the immune system triggered by the dengue virus. According to some scientists, the autonomic nervous system and the hypothalamic-pituitary-adrenal axis interact with the immune, endocrine, musculoskeletal, and neurological systems. This may result in post-infectious fatigue syndrome.
Why is Dengue known as Breakbone Fever?
Dengue is referred to as breakbone fever because of the severe pain and stiffness of the affected individual’s muscle, bone, and joints.
How Dengue causes thrombocytopenia?
Patients suffering from dengue have low blood platelet count. The low blood platelet count in medical terminology is called thrombocytopenia. Thrombocytopenia is observed in both mild and severe cases of dengue. The exact mechanism of how dengue causes thrombocytopenia is not yet known. However, scientists believe that thrombocytopenia in dengue patients can be due to the following mechanisms:
- High mean platelet volume in dengue patients leads to platelet destruction and clearance from peripheral blood.
- Decreased platelet production in the bone marrow
How to diagnose Dengue Fever?
Once a patient with the symptoms of dengue visits the hospital, the physician diagnoses dengue through the following methods:
- Initially, the physician asks the patient about the patient’s travel history and asks the patient about the symptoms they are experiencing.
- Suppose the patient has visited a dengue-endemic region or any place where recent dengue cases are rising. In that case, the physician suspects the person to have dengue and then looks for dengue symptoms.
Based on the physical observation and patient history, the physician moves towards diagnostic tests to confirm the suspense.
The diagnostic tests include:
- Nucleic acid amplification tests (NAATs)
The NAATs test is performed on the serum specimens collected from the suspected patients, seven days or less after the onset of the symptoms. The presence of the dengue virus is confirmed with rRT-PCR or NS1 antigen by immunoassay. - Serology tests
Serology tests include detecting IgM antibodies through immunoassay techniques like MAC-ELISA and rRT-PCR in vitro diagnostic tests. Cross-reactive flavivirus antibodies can form in people who have been infected with or vaccinated against other flaviviruses, resulting in false-positive serologic diagnostic test findings for dengue.
What are the different vaccines available to treat Dengue?
Dengvaxia of Sanofi Pasteur is the first WHO-approved vaccine to develop immunity against all the four dengue virus serotypes. The vaccine is given to people of 9-45 years of age who have a history of suffering from dengue. The vaccine is unsuitable for a healthy population, patients with compromised immunity, pregnant, and breastfeeding women.
The other vaccine candidates for dengue that are under clinical trials or research includes:
- DENVax by Takeda ( also known as TAK003)
- LAV Delta 30 or TetraVax-DV by the National Institute of Health (NIH), USA
- TDENV-LAV and TDENV-PIV by the US Walter Reed Army Institute of Research (WRAIR), in collaboration with GlaxoSmithKline (GSK)
- Plasmid DNA vaccine (TVDV) developed by the US Walter Reed Army Institute of Research (WRAIR), together with the US Naval Medical Research Center (NMRC)
- V180, a recombinant protein-subunit dengue vaccine developed by Merck Sharp and Dohme
What are the preventive measures to stay away from Dengue Fever?
At present, there is no specific antiviral medicine that can treat dengue. Therefore, supportive care is the best method followed to take care of dengue patients. Below is the advice you can take to protect yourself from Dengue or if any one of your close friends or relative is suffering from dengue:
- If you have a positive dengue test, keep yourself hydrated with water and avoid medications like corticosteroids, aspirin, and other NSAIDs. NSAIDs are not preferred because of their anticoagulant properties.
- Maintain a clean environment. Please clean the area or notify the health authorities if you find open cans, tyres, huge containers, coconut shells, broken clay pots, or vessels distributed as waste in open land. Mosquitoes lay their eggs in these areas due to the presence of stagnant water.
- Do not throw garbage in the sewage or block the sewage.
- Drink lots of coconut water and fresh orange juice.
- When going outside early in the morning or late at night, always use a mosquito repellent lotion containing chemicals like DEET, IR3535, or picaridin. Natural insect repellents such as lemon-grass oil and eucalyptus oil are very effective at keeping mosquitoes at bay. However, before using any mosquito repellent cream, please check with your doctor and follow their advice.
- Wear full pants, full sleeve shirts, hats, and shoes to prevent mosquito bites.
- Always keep the house neat and clean. Put door and window nets and screens to prevent the entry of mosquitoes.
- Kill mosquitoes with electric bats or with insecticides available in the market.
- If you have water storage containers, kindly cover the lid adequately. Then, every six months, call a pest control team, and they will clean your house correctly and git rid of any eggs and larvae of mosquitoes.
- Use mosquito nets while sleeping. Always keep yourself protected. It is crucial to ensure that each room in your home receives adequate sunshine.
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