– By Hussain Asif, Atta-ur-Rahman School of Applied Biosciences
– Comic by Maha Nadeem Akhtar, NUST Science Blog
Just as I came to know that bermudas and sleeveless shirts have been banned in our hostels, as a virology undergrad, I immediately felt like trying to tell fellow people about the nature of this dengue virus and the whole thing so that maybe I could comfort you people and put your mind at some ease! So let’s briefly analyze the two key players of this disease, so that we can know what got wrong. Let’s take a look at our very own dengue virus and the not our very own vector (transmitter, carrier) of this virus, Aedes aegypti.
Yes, that’s right, it is our very own and local virus which has been around for at least 200 years and is now endemic to Pakistan, thanks to uncontrolled urbanization and a guest mosquito specie. Endemic disease is a condition which is native to an area, i.e. HIV or AIDS is endemic in African countries, meaning the disease is established in that region, whereas an epidemic is a state of disease in which it causes devastation more because of its contagious nature – one depicts origin and the other intensity. Because of different factors, dengue virus is established in the area to some extent, by established I mean it has a reservoir in form of hosts and transmitter in form of mosquitoes. Not to worry, since being established DOESN’T MEAN AT ALL that it will cause havoc in the area. The thing is, dengue is dependent on its transmitter for changing from an endemic to an epidemic, so essentially if we take care of the transmitter, there won’t be an epidemic.
The reason behind how it established in this area is that dengue has been thriving for decades in India and Sri Lanka with rare cases in Pakistan, but no one ever noticed it because the cases were so less, and that dengue doesn’t usually kill at all!
Let’s try and understand the behavior and dynamics of this disease a bit. First, that if one is infected with dengue then that doesn’t mean that he will necessarily suffer from the dreaded DHF as well! (dengue hemorrhagic fever, which is the most dangerous but still not so lethal form of dengue infection) rather it’s much more likely that he will recover completely in a few days simply after fever.
Coming to the relatively complex bit, dengue in Pakistan and adjacent areas has four serotypes circulating in the area (serotypes is somewhat synonymous to siblings, to make it simple). If you get infected with a simple serotype, then that is rarely a big problem, the problem starts when a person gets infected by multiple serotypes multiple times! Even then you have an increased chance to get severely ill.
The primary root of all epidemics lies in multiple causes. Of course there are bigger causes and the smaller causes but one has to understand that epidemics are somewhat like jig-saw puzzles. If an epidemic has to cause maximum havoc, all factors should be complete.
This guest mosquito, Aedes aegypti (for future reference I will use AA) which is known for its ability to survive in urban environment of developing countries, was transported all around the world from Africa during 1950’s out of ignorance and mistake. Some experts hypothesize that during World War II and afterwards, through movement of troops and cargo between different areas, this mosquito ended up in South East Asia. We know it came from Africa but the exact route is anyone’s guess. From evidence, it looks like it moved from Africa to South America to Hawaii and eventually to Burma and adjacent regions, ultimately ending up in countries like India, Sri Lanka and finally Pakistan.
There are other vectors as well, but technically speaking none of them is as well adapted to our typical urban setup as AA is. Its breeding places are fresh water reservoirs and small containers like a vase or a can or a bowl (especially old and used rubber tires). Another facility that we have given to this Mr. AA is tightly packed living in cities like Rawalpindi, Lahore, and Karachi. I insist that this is the actual problem which is worsening the situation. What we have done is that we are living in a highly concentrated manner providing AA with plenty of food in close proximity, and then because of our poor awareness we have housed them in our own homes and streets.
Let’s place the pieces together; the real problem is when a person gets infected multiple times by multiple serotypes. Since we are living in such dense cities (ever wondered why dengue hit Lahore most?) and we have this uninvited guest as well, therefore we need extra care to keep this problem away. The only short term solution to this problem is to take care of the vector and keep your living space free from it. Dengue virus is not as problematic as it sounds, it’s us who have made it problematic because of poor planning and prevention so honestly its no use crying over spilt milk! Our option is to kill the vector and prevent multiple bites, and to be honest government alone can’t do it because we all know about their resources and their abilities (I don’t mean to undermine their efforts by the way, ’cause as news tells me CM of punjab has gone to war against this problem :P).
To lighten things up I would give you some statistics from noted experts from Sri Lanka;
They had 35000 cases of dengue in 2009, 350 died.
In 2010 they had 350 cases only because of proper prevention, and lucky for them, only one patient expired.
Don’t you go saying that Sri Lanka and Pakistan have no comparison and that our government is corrupt, etc., of course we do and Insha’Allah we will definitely take care of this epidemic. So stay calm, spread awareness and follow all precautionary measures and everything will be fine eventually, and since this mosquito is a day time feeder with maximum bites at the time of dawn and dusk so sleep tight (not to mention its dawn at 6 am when most of us NUSTians are sleeping :P)
Oh, and here is some food for thought if some of you would like to look into this matter, from the statistics given above (regarding Sri Lankan population) can anyone of you calculate the mortality rate of this so dreaded aliment? Just for a hint, Hepatitis C virus has a mortality rate higher than dengue! Ever worried about that?