As we see from the graph, there was a decade long effort to combat the exponential rise of 1970's. I find a few reasons for the failure of those.
The inefficiency or lethargy of the feed back system gave sufficient time for the problem to grow high.
The weapon (DDT) used in the earlier attack had lost its striking power since mosquito had developed resistance against DDT by that time.
Probably there would not have been liberal cash flow as in the case of previous occassion.
Even though the graph show high rise, till 1970 the total annual # of cases were less than a megere 500 and so its quite likely that the implementing agency would have handled the situation very lightly! This could be the reason why the toll could not be brought below even 50%.
Another reason can be the smallness of the absolute number of cases. It was only 6000 in a population of 25,000,000 and it was brought down to 3000 (ie 0.024% brought down to 0.012%). Achieving figures below that may be like 6-zigma goal. I don't say it is unachievable, because such a goal was achieved in the previous project. As I mentioned earlier in this comment, the implementing agencies would not have felt the need for that.
The almost vertical rise of graph (ascending like a rocket) after 1986 (which marks the end of second project) and the almost horizontal progress (ascending like an air craft) of it during 1964-72 tells us about the loss of efficacy of DDT in destroying mosquitoes.
A google alert mail to me last week on mosquito control news says that residual DDT spraying is started in xxx country (I forgot the name. After all name of the country is immaterial in this case. Which ever is the country, our fellow human beings only are going to suffer the ill effects of that!). You must be remembering that the WHO had banned the use of DDT some 3 decades ago telling that its use is harmful to animal & bird life forms. In 2007 they lifted the ban. Then I tried to make it an issue, but it didn't catch up. What an individual like me can do other than shout in wilderness to be unheard?
Now I have a question: Has the WHO or anybody for that matter improved the DDT and made it safe/harmless to humans atleast????? Has anbody tried to confirn that DDT can still destroy mosquito as well as remain harmless to other life forms? If not what is the credibility of the WHO? ULTIMATELY WHICH DECISION OF THE WHO IS THE RIGHT ONE - THE BAN ON DDT OR LIFTING OF THE BAN ON DDT?
The Government DID act but its sword had rusted by that time!
As we see from the graph, there was a decade long effort to combat the exponential rise of 1970's. I find a few reasons for the failure of those.
Now I have a question: Has the WHO or anybody for that matter improved the DDT and made it safe/harmless to humans atleast????? Has anbody tried to confirn that DDT can still destroy mosquito as well as remain harmless to other life forms? If not what is the credibility of the WHO? ULTIMATELY WHICH DECISION OF THE WHO IS THE RIGHT ONE - THE BAN ON DDT OR LIFTING OF THE BAN ON DDT?