When Martinho Somandjinga, Manuel Lluberas, Joaquim Canelas and I started the US PMI in Angola in 2005, the excitement and pride of our accomplishments carried us along for the first couple of years. Sure we spent over two million dollars in one small province each year, but it seemed worth it.
But as the years went on, and before we sprayed each of these houses, and we had to ask the folks to move all their food and furniture out of the kitchen or dining area, I couldn't help wondering if it might not be smarter to control the mosquitoes with another method, something more permanent. Like maybe reducing the number of breeding sites near the homes. The breeding was quite focal, and also very seasonal, closely related to the rains. And the land was flat, with lots of marshy areas in the small floodplains along the intermittent streams. Also there was a simple irrigation system with lots of flooding problems in the rainy season as it lacked even a simple drainage network to complement the irrigation ditches.
In 2006 we had to do the spray again, for another 2 million dollars. And again in 2007. And in 2008, and every year since, for 9 years now. The US PMI has now spent about $200 million in that part of Angola, and about a third was for indoor spraying - roughly $70 million. The waste in all this is that the effect of that $70 million lasts about a month, then it is gone.
Suppose we had started spending half of the money on permanent mosquito control measures such as reclamation of the floodplain swamps so they could plant crops there? And digging simple drains to complement the irrigation ditches?
Who would do this work? Obviously it is the kind of thing that local farmers and laborers could do. All they need is a pick or shovel. Even I know how to dig a ditch, and I'm not much of a farmer.
Land reclamation would not eliminate the need for spraying in truly wet years, but it would reduce it drastically. And each year we could have built out more and more breeding sites - permanently. Meaning more years when mosquito production is minimal.
That is another real advantage of land reclamation and drainage for mosquito control. Because its effect is permanent, each year the covered area expands. However spraying has an effect for only a few months, then we are back to Zero, and it has to be repeated - every year, forever. That means purchasing biocides, buying new spray cans, and new protective gear for the spray crews. And every year the homeowner has to move everything out of the house before the spray. After 2-3 times it starts to produce resentment against the spray campaign.
Another advantage of permanent land reclamation is that by reducing the frequency of spraying, it takes off the pressure toward the Resistance Treadmill.
We could have done a lot of land reclamation in Angola by now. with even half of that $70 million. And who would get the direct financial benefits from the money spent on ditching ? Mainly the local subsistence farmers who could be hired in the off-season. But who benefits when we spend $2 million each year on biocides and spraycans ? The chemical company Syngenta, or whoever sells the new carbamate that has to be used because of the mosquito's resistance to pyrethroids, and also the Hudson Company of Chicago who makes the spraycans. I have nothing against either company, but I would prefer to see the money go to the local farmers.
While laborers are also hired for spraying, they have to do the work quickly in a matter of a month or so. In contrast the ditching and filling of depressions can be done gradually over the entire year and is thus a much better job to have, instead of the temporary spraying job.
And one more practical advantage - avoiding the Immunity Dilemma. Malaria programs often fail after several successful years. If the program was based on ephemeral methods such as spraying, then the young children have no immunity against malaria and will suffer enormously. But if the methods used were permanent and durable, the temporary lapse of effort will have little effect.
So to summarize - the benefit of permanent methods such as land reclamation vs ephemeral methods such as spraying, are:
1. Fewer years when spraying is needed
2. Reduced pressure towards the Resistance Treadmill as spraying is reduced
3. Increased land for local agriculture
4. Better jobs for local workers to do the ditching
5. Less disruption of homes during spray operation
6. Reducing the Immunity Dilemma
7. Accumulated area of eliminated breeding sites
This last benefit is important, the accumulated impact from such permanent methods. I think it also explains why malaria does not return to places like Italy or the Holy Land, even though there are plenty of introductions of vectors and infected peoples. As the decades pass, the remaining area of breeding sites shrink and almost disappear.
It is one thing to be pleased with the quick effects of indoor spraying, but it is another thing to keep on doing the same thing forever. Gradually introducing permanent improvements will also gradually reduce the costs, and eventually build out anopheline breeding. In some respects, it is even an Exit Strategy - maybe even before the advent of the mythical vaccine.
Bill, ready with my pick and shovel