With likes of zika, dengue, rabies, Chandipura, chikungunya, H1N1 regularly appearing here, this column should be getting really viral, but it seems to lack the punch. So, I am tempted to invite HIV, the AIDS causing virus with highest TRP to join the party!
I often feel tempted to scare my readers (and in turn, city administration) with a truly horrific possibility, i.e. AIDS spreading through mosquito bites. Before you jump out of your chair, I must admit that it is not happening and not likely to happen due to certain technical limitations that the virus-mosquito duo has not been able to resolve as yet.
Even though AIDS spreads through transfer of infected body-fluid from person-to-person, it is not spreading through mosquito-bites because HIV has very low presence in the blood of the infected person. Due to this very low viral load, even if a mosquito bites an AIDS patient, it is not likely to get enough viral material to carry infection.
The other, and possibly the biggest, saving grace that stops a mosquito from becoming agent of, not just HIV, but all parasites is its blood-sucking mechanism. One may take poetic liberty and call mosquito a flying hypodermic needle, but technically it is not. A mosquito uses two different tubes, one to pump in its anticoagulant saliva and another to suck out the blood. This separation is one of the luckiest breaks for us all. Viruses like dengue/zika (or parasites like plasmodium) have found a way to migrate to the salivary glands of the mosquito and enter human body via mosquito saliva. But HIV has not yet managed to bridge the gap. So, even if it may reach inside a mosquito, it has no way to travel back into a human host. In fact, as HIV needs T-cells to latch onto, their absence in mosquito-gut leads to its demise through digestive process of mosquito.
It is highly reassuring that AIDS is not going to be flying on mosquito wings amidst us, but the annoying fact remains that, if it can it would surely have an evolutionary benefit. And that holds the real key to a bigger issue, i.e. how to deal with threats posed by nature that uses evolution for problem-solving?
Evolution is a game of numbers, really big numbers, and probability. In distant past, dengue or plasmodium must have been equally incapable of getting past mosquito-gut into its salivary gland. It happened because there was benefit in evolving this ability. Given enough opportunity, life-forms show great ability to capture and capitalize any advantage that exists. HIV cannot ride a mosquito today, but if given enough chances, it may.
By opting for dense urbanity, humanity has created a unique opportunity for parasitic evolution. With so many bodies available to infect in close proximity, our cities are shifting the probability in favour of faster evolution of all parasites. A city like Ahmadabad offers a unique and unprecedented opportunity to a virus like HIV, as its chances of interacting with mosquitoes are dramatically increased. Even if it is one-in-trillion chance, we could be creating theoretical possibility of its realization.
The real key to mitigate such problems is to curb the numbers, as they only can slow down or even stop evolution from unleashing epidemics. Our constantly increasing mosquito population is changing the evolution dynamics of disease causing parasites. And the only way to hold them back is to cut the mosquito numbers down drastically.
It is strange that, even after such a massive threat exists, as per the latest AMC budget, we are still keen on building more water-retaining structures to “beautify” the city. I really hope that we stop playing with the fire and recognize the destructive power of evolution.