Do the Prime Minister of India and Chief Minister of Delhi – and their mandarins in the health and urban ministries – realise that the deadliest stalker on Earth is the mosquito? Mosquitoes kill more than 0.8 million people in a year; humans clock in second with 0.5 million. The lion slaughters a mere 100; snakes kill about 50,000. Yet, astoundingly, in all the din most anchors and panelists on television debates raise, they’ve been unable to pronounce dengue correctly (it’s den-GAY-i or denGEE, not denGOO).
The emphasis in fact has been, with some justification, on slinging as much mud as possible at Delhi hospitals, but not at all on the ramifications of all the dirt in the city we live in or how we permitted millions of mosquitoes to breed in an urban settlement in the first place.There has not been the slightest suggestion to remove all those puddles of water, or even of administering a vaccine to mitigate the next outbreak.
The mosquitoes have exposed us for what we are. Sure, Yemen is also experiencing an epidemic right now, but it has the excuse of a civil war raging within its boundaries. On the other hand, Nirman Bhawan has the luxury of fudging data; the bureaucracy is often startlingly similar to the SHO in the local police station who cringes when asked to record an FIR for manifest reasons. And while it’s the time to hear from all the health secretaries and the administration of Delhi, they all appear to have gone underground.
Dengue is produced by a virus that has four serotypes (call them subtypes): DEN-1, DEN-2, DEN-3 and DEN-4. Delhi has been struck this time by DEN-4. However it makes little clinical sense to know of the serotype causing an epidemic because there is no treatment available. Management of a case is largely symptomatic and supportive. The disease comes on suddenly with high fever, headache, muscle or joint aches and a rash. The headache is peculiar in that it is localised behind the eyes. Because of the aches and pains, dengue is also dubbed breakbone fever. The fever should be tackled by cold compresses, a cold shower, or paracetamol. Aspirin or brufen should never be used because they will aggravate hemorrhagic tendencies. A lot of patients may seem symptomatic or may have mild symptoms. About 1-5%, however, may develop hemorrhagic dengue fever (HDF).
Severe dengue fever is explained by a repeat infection with a different serotype. Let’s presume the first episode was by DEN-2 and the next infection is underway by DEN-4. The body initially fails to recognise the new virus serotype and remains laid back. When it eventually does figure out that there is a new intruder, it reacts by storming the virus with humongous amounts of antibodies. This firestorm of antigen-antibody reactions results in massive reduction of platelet counts (which are anti-hemorrhagic cells shaped like dinner plates) and leakage of blood vessels. The walls of the blood vessels are badly compromised, leading to copious amounts of fluid oozing into the extravascular space. This in turn leads to a thready pulse and shock. In such cases, mortality can be as high as 20% or more.
Dengue is clinically recognised by the trifecta of fever, headache and rash. It can be confirmed by a spot test that detects the antigen on the first day itself and by PCR assessment. The white cell numbers get lowered, liver enzymes increase, and the platelets’ count begins to fall. In most Indian cities, malaria, typhoid and plain viral fever should also always be kept in mind.
Genetically modified mosquitoes to eliminate their peskier kind seem an attractive proposition but are yet to be tested in the field. There are many social and environmental costs, usually glossed over by the companies selling the technology. Pilot tests have been conducted in Brazil but here in India, we ought to take the clarion call of “Swachch Bharat” more sincerely and make it difficult for mosquitoes to spawn.
A female mosquito can lay from 300-500 eggs at a time. She doesn’t draw a distinction between clean or polluted water. All she wants is for the water to be stagnant for the eggs to hatch and larvae to emerge. The water could be in a vase, a flower pot, an old tyre, a water cooler, anywhere. Surprisingly, despite the mosquitoes breeding within homes, no fogging is attempted inside residences. Nets are ineffective at night because the Aedes aegypti strikes during the day.
And unlike her male partner, who might as well be a strict vegetarian, the female mosquito needs blood to lay her eggs. She injects an anti-coagulant when sucking human blood and in the process transfers the dengue virus located in her salivary glands.
It would be perilous to underestimate her fortitude and ability. She does her job with minimal fuss, perfected over a 100 million years. We are sitting ducks against a virus that has no antidote as yet and which can take out both children and adults. It therefore becomes imperative that we clean up the neighbourhood ourselves without waiting for stuporous municipalities to react. It is also imperative that we become better prepared for the next epidemic and give serious thought to immunising children (as it happens, a recently developed vaccine boasts of 60% efficacy in children, and has been found to be safe and to substantially reduce the chances of serious infections and hospitalisation).
Deepak Natarajan is a cardiologist in New Delhi.