Post monsoon, the Dengue dread is back in our cities, with over 650 cases reported in the national capital alone. In 2017, data from the National Vector Borne Disease Control Programme (NVBDCP) and National Health Profile 2018 indicated the maximum number of deaths in a decade and a 300% hike in the number of cases.
Will there be a fall in the graph this year? There are mixed reports so far, with some evidence of control in a few cities, but a sharp spike in others. The reason for the continuing incidence is simple: poor urban management and lack of cleanliness.
But what causes dengue and when should you really worry about it? Is there a way to prevent dengue?
Check out this comprehensive guide and stay healthy.
What causes dengue?
The tropical, mosquito-borne dengue or ‘break bone’ fever is caused by a virus that is virally prevalent and worryingly virulent. It is caused by the Aedes aegypti and, to a lesser extent, Ae. albopictus mosquitoes.
Its premium carrier is a ‘synanthropic’ species that is fond of artificial habitats created by humans. It likes to thrive in fresh water on hard surface containers near and around its large food sources – human blood, according to Dr Arjun Isaac, Associate Professor at M S Ramaiah Medical College, Bangalore.
Like other viruses, dengue too has undergone mutations. Dr Nalini Subbaiah, a paediatrician in Mumbai, explains that there are four distinct, but closely related serotypes, which are separate groups in a species of microorganisms. They share similar characteristics and symptoms. A fifth strain has been detected in East Asia, but has fortunately not travelled to India yet!
What transmits the virus?
Once the mosquito gets infected, the virus is in incubation for four to ten days. After that, the mosquito transmits the infection as long as it is alive.
Another carrier as well as a multiplier of the virus could be… You, if you are an infected human!
You might seem symptomatic or asymptomatic for a while, but if you are harbouring the virus, you would actually infect the mosquito biting you! Patients who are already infected with the dengue virus can transmit the virus after an incubation period of 4–5 or even 12 days. It has been found that the maximum number of virus transmitters are those who show little or no symptoms of the illness. Hence, they have not approached any doctor or got any treatment, and thus they might actually be harbouring and spreading the illness.
Why is it such a dreaded word?
Dengue is one of the most extensive mosquito-spread diseases today and infects people round the year, even though outbreaks and fatalities make it to the headlines most often during and after the rains.
Ironically, it should really not create the panic that it does, because it most often kills less than 1% of the patients! Due to reports of severe strains and fatalities pouring in from across the nation, citizens are on tenterhooks and paranoid, especially in cities like Delhi, Kolkata and Bangalore that have had a history of major outbreaks.
How often is it curable?
According to Dr Venkatesh Reddy, a general practitioner in Bangalore, with early detection and clinical support, the mortality of the disease can be brought down to about 1%.
When does the Dengue mosquito bite?
This is one virus that flourishes when the day is warm and humidity is high. Earlier, a spike in the illness was noticed usually in September and October. Experts say that the mosquito which is responsible for the spread of the virus only breeds at a temperature higher than 25 degree Celsius. However, alarmingly, the mosquito is now breeding in all seasons.
The female Aedes aegypti bite multiple people during each of their ‘feeding’ months. The mosquito buzzes most often two hours before sunset, that is around 5 to 6 pm and again from 8 to 9 am. Being a “daytime feeder”, these are the hours when it affects patients the most.
Where does it breed?
As dengue threatens half the world today, it has become a severe global viral bomb. It is a uniquely urban or semi-urban disease that is rampant in tropical as well as sub-tropical global climates, and Indian cities are among the favourites of this mosquito species.
According to the Ministry of Health and Family Welfare, south Indian states are at greater risk, as the temperature fluctuations are less here, which is ideal for its breeding.
Aedes aegypti usually multiplies in man-made containers of stagnant water, and remains active in dark or shady places.
Worryingly, of late, they have been found to breed inside homes very often, where temperatures may be higher than outdoor locations. Such breeding grounds for the virus are found not just in lower-income but even in middle or upper class homes.
What are the symptoms of dengue?
Dr Mukesh Mehra, Senior Consultant, Internal Medicine, Max Superspeciality Hospital (New Delhi) has said that 80 per cent of dengue cases are asymptomatic. That is, the patients show no clinical signs or symptoms of disease.
Some patients at first show symptoms of only mild illness, with rising temperature and headaches. Almost flu-like. It hits infants, children and adults. For higher temperatures of 40°C or 104°F, the fever is accompanied by severe headaches, aching behind the eyes, tired muscles and joints, nausea, vomiting, glandular swelling and rashes. After two to seven days, or after an incubation of 4–10 days after the mosquito bites, the bitten might get severely affected.
How do I know whether I have viral fever or dengue? At what stage is this known?
Dr Venkatesh Reddy in Bengaluru pointed out that even with symptomatic fevers, it might be difficult to distinguish it from regular fevers. But any cases of fever should be tested, diagnosed and treated on time.
Hence, you cannot immediately know whether you have dengue or other fevers. Only tests can help you to find out.
Can I have dengue even if the test results are negative?
Your doctor would take Immunoglobin G (IgG) and Immunoglobin M (IgM) tests for dengue antibodies. If both tests are positive, then you have been bitten in recent weeks. If the IgG is positive but the IgM is low or negative, then you most probably had an infection sometime in the past. If both tests are negative, then you can cheer and go for a ball. You aren’t bitten.
What confirms Dengue?
Dengue can be confirmed when a patient’s platelets drop or an increase in blood haematocrit is noted. However, even patients of dengue who are anaemic might not have high haematocrit.
A normal platelet count in a healthy individual is between 150,000 and 450,000 per µl (microlitre) of blood. If the patient’s platelet count falls below 50,000 per µl then one must prepare to arrange for platelets. Normally the doctor advises platelet transfusion only when platelets count falls below 30,000 per µl.
Can I have dengue more than once?
Yes, you can. There are four strains of the villainous virus.
What are the ‘serotypes’ that I keep hearing about? Is one worse than the other?
The Dengue virus may have four serotypes, or genetic variations, within a single strain. Still, infection with each dengue serotype exhibits the same disease as well as a range of clinical symptoms.
The four serotypes of the virus leading to dengue include DEN-1, DEN-2, DEN-3 and DEN-4. By recovering from one of these infections, you can get the honour of immunity from that serotype throughout life. But it does not shield you from the other serotypes fully, and recovery might be only partial and temporary. This explains why you might fall prey to the disease again, contracting dengue of other types.
Dr Subbaiah explained that while every serotype undertakes a different interaction with antibodies in the human blood, all four viruses are similar. They share about 65% of their genomes.
Of the four strains, DEN-2 is the most “dangerous and life threatening”. DEN-3 is said to be the mildest and least severe form of virus, as compared to Type 1, 2 and 4. It does not trigger the “fatal drop in platelets”, haemorrhagic fever, organ failure or Dengue Shock Syndrome (DSS) and thus leads to less casualties. However, it might still move on to high-grade fever.
When does ordinary dengue turn into the severe type?
If you detect the virus early and take clinical support as well as lots of fluids, you can fight it. If not, get ready for the severe attack.
Dr Subbaiah said that dengue gets transformed into its most dangerous form only about 5 per cent of the time. In this form of ‘severe dengue’, serious complications arise along with fever, and might lead to some ‘shock’ in the circulatory system or organ failure, leading to death. This is called the Dengue Shock Syndrome.
If you recover, it is good news, but sometimes, there might be worse to come. While you may develop immunity from the particular Dengue virus serotype, if you happen to be infected with a different serotype, repeated infections could reduce immunity over time, leading to Dengue Hemorrhagic Fever, which might be fatal.
So when is dengue fatal?
Apart from Dengue Hemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS), the rare Hemophagocytic lymphohistiocytosis (HLH) strain could also prove to be a killer. It has a high mortality rate of 80%. It is a condition in which white blood cells build up in the liver and spleen and attack other blood cells. Six patients in Pune are reported to have contracted it, but thankfully, it is not known to have spread to other parts of the country yet.
How can fatalities be prevented in dengue, if at all?
Severe dengue, as the name suggests, is complicated. It comes with plasma leaks, accumulation of fluids, acute distress due to respiratory problems, serious bleeding, and even organ impairment.
Just three to seven days following the initial symptoms, you might notice a drop in the temperature to below 38°C/100°F. But there continues to be
acute pain in the abdomen, persistent vomiting, rapid breathing, bleeding gums, fatigue, restlessness and blood in vomit.The next 24 to 48 hours are critical, so proper and sustained medical attention is needed to avoid complications and risk of death.
For the deadly HLH strain, the symptoms are at first mild and a patient even seems to recover. But after a couple of days, there could be a severe relapse requiring re-admission of the patient. The fever peaks and may be accompanied by multi-organ failure, of the liver, kidneys and heart.
What are the medications available?
Worryingly, only supportive, not curative medications, work. There is no specific treatment for the fever. Timely intervention can reduce mortality rates from 20% to less than 1%.
For patients of severe dengue, meticulous and expert medical care along with careful documentation of the rate of progress is important.
It is important to give the patient lots of liquids in order to maintain the fluid volume. To relieve pains, aches, fever and headaches, aspirin or other NSAIDs such as Ibuprofen or Diclofenac should NOT be given. Instead, paracetamol is recommended.
Sponging the patient with a wet towel, for 20 minutes at a time, can help.
Some home remedies include papaya leaves, basil tea, kiwi fruit and wheat grass juice. However, while these are not confirmed to be medications, they can be taken as placebos while maintaining continuous fluid intake.
Can people be immunised against dengue?
When a pregnant woman gets infected by the dengue virus, her antibodies get transferred to her foetus. That is an interesting, temporary protective shield for her baby.
For other patients, there is some good news. The first dengue vaccine, Dengvaxia, has been developed by Sanofi Pasteur. Even though it was given the green signal by 20 countries and accepted for use by people aged between 9-45 years, it has not been adopted in India. Dr Soumya Swaminathan, director general of the Indian Council of Medical Research (ICMR) suggested that it would be “premature” to introduce the vaccine in India.
How can dengue be prevented?
The most effective form of dengue control is vector (mosquito) control. Stop it from buzzing around you all the time. Stop it from nosing out egg-laying habitats.
How do you do that? Simple. By keeping your environment clean.
- Segregate your waste and dispose of it all efficiently
- Clean up the artificial, man-made habitats
- Cover, empty and clean your domestic water storage containers regularly
- Sprinkle the right dosage and quantity of insecticides to storage containers
- Make use of household protection devices such as window screens, mosquito repellants, coils and vaporizers
- Use long-sleeved, white and loose clothes, as mosquitoes find it more difficult to bite through them
- Get your neighbourhood to fight the battle with you
- Spray insecticides and repellants for important emergency vector-control, but read the instructions for babies, infants, pregnant and lactating women
- Monitor and survey vectors efficiently
What can the government do?
First of all, it should stop fogging, which is used often by the municipalities to “kill mosquitoes”. However, releasing chemicals like pyrethroid or malathion, which are also found in domestic insect spray cans, is of no use. The insecticide is mixed with water droplets and sprayed through fogging machines in order to cloud out the insects. But it is conducted far away from homes, so it has no effect at all on the dengue carriers in most instances.
What city governments can do instead for more effective control is create awareness of the illness, its causes and focus on cleanliness to wipe out the villains. You should involve the whole community too.