Urban Planning Vector borne diseases

HxNy is Afridi but dengue is Hashim Amla

I have noted that every time Shahid Afridi takes strike, fear strikes the hearts of Indian fans; but when Hashim Amla comes to crease there is hardly any flutter. Interestingly, this phenomenon reminds me of another completely unrelated duo i.e. swine flu and dengue! 

This is so because, when we really rise above the fear-response and look at the hard facts, a completely different and curiously similar picture emerges in both cases. 

When we look at the real numbers it becomes abundantly clear that, compared to deadly AmlaAfridi that we fear is nearly harmless. Against us, Amla goes past fifty in every second inning, while Afridi does it in every eleventh, and yet, Afridi causes us to huddle and often panic. 

The AfridiAmla-phenomenon shows us that we get overwhelmed by the dramatic and ignore the persistent. It is a trait we need to be extremely wary of, especially in dealing with air-borne/contact and vector-borne viruses that are fast becoming alarmingly damaging.

There is no doubt that swine flu (H1N1) if evolves by meeting some other influenza strain can become destructive and must be feared. The HxNy viruses are of Afridi pedigree. On their day, with right genetic combination, they can cause unprecedented damage at a rapid speed. 1918 Influenza epidemic that killed nearly 5 % of world population showed that some variants of HxNy must be taken very seriously.

But, most variants of HxNy (like the H1N1 that is around this season) are just seasonal malaises that are rarely very dangerous. They come and go, just like Afridi, very often not even bothering the scorers. This is because, what works in favour of the virus is also its limitation.

HxNy is a virus passes from person to person via respiratory fluid droplets entering host through nose/mouth or via soiled hands carrying the virus to nose/mouth. This allows the virus to spread rapidly in a social species like humans and more so in crowded urban areas. But, what works in our favour is its short shelf-life. HxNy, outside its host, at its very best, survives for about two days on non-porous surfaces like stainless steel and only for about one day on surfaces such as cloth or paper.

This means that HxNy infections can come and rage but can also be stopped by putting a plug on contact between people.Once it is stopped from finding new hosts, it will run to ground, a process that is hastened by unfavourable summer weather. 

This means that though killer strains like bird flu (H5N1) may arrive in one season, they rarely make across the summer into the next. 

HxNy versions like the ongoing swine flu are dramatically aggressive like Afridi on a good day, but they lack staying power of Amla, who reminds me of yet another virus i.e. dengue.

Dengue virus is not as deadly as the H1N1 strain that is causing havoc in Gujarat, but it needs to be taken even more seriously as, just like Amla, it uses better techniques and is far more persistent in staying on the crease. This is possible due to its unique talents that are not really understood by all the stake-holders in disease mitigation business. 

Unlike HxNy, dengue rides a formidable force, the mosquito, allowing it a greater reach across any barriers that we may put to contain it. And by linking its fate with an insect, dengue has also availed the advantages of this hardiest class of life-forms. Insects are around since 400 million years and have learnt every trick in the trade to survive. They evolve fast to circumnavigate threats (eg. DDT) and can breed in astronomical numbers in fair weather to ensure continuation across bad times. These traits of mosquito are used by dengue to make it the Amla of a virus, who will have a damaging run in every inning. 

Compared to HxNy’s survival of a day or two outside its host, dengue manages to extent this to months. This is done by dengue virus using an extremely curious method technically known as “vertical transmission”. When inside it’s mosquito host, the virus travels into its eggs turning the next generation of mosquito in a ready-to-infect hypodermic needles. 

Aedes aegypti, the mosquito host of dengue, lays its eggs not “in water” but on the side of the container. These eggs are capable of surviving for months in dry state and can “return to life” with they access water. So virus simply sits safely inside the eggs to return every season.

What is even more dangerous about dengue is the way it can use our only true defence, our immune system, to its advantage in a re-infection.

In very simple terms, dengue virus comes in four types. When a person is infected by one type, his body will develop an immune response to that type. Unfortunately, if the same person gets visited by other strain of the virus, it actually “rides” the immune system response to cause more havoc. That means that every new wave of dengue becomes more potent.

It is good that swine flu has woken us up to the threat of viral diseases, but we must evaluate the risks of each pathogen and provide a measured response, because, in Ahmedabad, it is not just Afridi or Amla comes to bat every season, we also have the great (arguably the greatest) of them all, Sir Don himself visiting us every season. Malaria, the greatest killer of all time is given the most favourable pitch by us every year and we seem to be not looking at the scoreboard.

I am happy to admit that I have managed surviving till now with minimum effort as all my intellect has be used to avoid doing anything meaningful. As I needed to while all the free time I generated in course of being lazy, science has been my favorite muse that I have enjoyed company of. As an effort to kill time (in a way, to get even with it) one fine day I decided to write a science column, more for my personal amusement than to attract readers. After getting educated about the attention span of modern readers from my editor, it became more like a challenge to tackle esoteric subjects in 600 words that I have managed to remain interested in for more than a year now. I do not want to add my worldly profile here as these are ideas that need to be considered only on the merits they carry and not as an opinion of a certain human being.

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