It may appear strange, but very often biology is best understood using corporate terminology!
All corporates know the power of logistics/transportation infrastructure. Whenever one wants to launch a new product successfully, pre-existing logistics infrastructure increases the possibilities of success enormously. Markets with pre-existing infrastructure are, thus, most susceptible to introduction and success of new products.
It is not exactly a matter of pride, but we must admit that our cities have developed world-class logistics infrastructure. Unfortunately, this claim to fame is not for product delivery but for pathogen delivery. With pre-existing vectors, especially mosquitoes, proliferating in increasingly favorable conditions that we are creating, we have put in place a ready-to-use delivery system that any virus can come and exploit to be a roaring success. In these circumstances, dengue virus throws up a possibility that, I am hugely surprised, has not caught anyone’s attention.
Dengue has four strains (DV-1 to 4) gallivanting across India. Gujarat, at this point, is more prone only to DV-2 strain, but it is just a notional comfort, as there is nothing stopping a new strain from arriving and exploiting our mosquito-network.
But, what makes arrival of a new strain of dengue more dangerous?
Dengue is actually not a huge threat as a single infection. In most cases, it passes away after giving you flu like symptoms and a bit of body ache for few days. Only in few cases, it leads to complications ranging from internal bleeding (DHF: dengue hemorrhagic fever) that can even turn into a severe and life threatening shock (DSS: dengue shock syndrome). It is the DHF-DSS phases that make dengue a potential killer, and this is where the arrival of new strain changes the equation in a scary way.
Scientists have now discovered that probability of simple dengue turning into dreadful DHF increases dramatically when a person catches dengue for the second time. This is a very counter-intuitive discovery; as, in most viral infections, our body manages to develop immunity to re-infection. While countering any infection, our immune system develops an antibody specific to invading pathogen. We retain some copies of each antibody to recognize the enemy if it enters again, making our immune-system a formidable long-term defense, but for the wily customer that dengue virus is.
Armed with more than one strains, dengue virus turns our immune defense strategy to its own advantage. In case of infection by a new dengue strain, the antibodies developed by body in previous infection still work like beacons that attract white blood cells to devour the virus. Unfortunately, due to its slightly different structure, the new strain manages to capture the cells that engulf it and uses them to put its own replication on fast track. Riding safely inside our immune system, the new strain now spreads rapidly, often turning into potentially fatal DHF-DSS.
It is abundantly clear that, after many waves of dengue that have passed through our cities, most of us have gone through the first infection (please note that if you are fit person, you could have passed through the infection with no symptoms!). So, it is entirely possible that a new strain can arrive amidst us and spread across our mosquito-supply-chain to exploit the glitch it has found in our immune system and cause havoc.
At this point, we have no way to stop arrival of a new strain of virus, but we need to understand the huge threat-potential and consider vector-mitigation with far greater intensity. The cleaning staff of municipality armed with white power that they randomly pour in puddles and spread on the garbage dumps is just increasing insecticide quotient of our already polluted environment and not serving any real purpose.