This looks like an exciting cause, but I’m not sure why we should have confidence that this screwworm can be completely eliminated in the near future. I know it has been eradicated from central America which is very impressive, but many diseases have been removed from much of the world (malaria, polio, measles, cholera etc.), yet are far from elimination. I have had a very cursory look at literature and I haven’t seen a strong argument or pathway as to why eradication might be probable—maybe someone could point me to it. There are a number of reasons this might be very, very difficult
(Note that I’m a global human health guy so basing my reasoning mainly on that, so I might be missing important things here)
1. Humanities track record so far (the best way to predict the future is look at the past). Only smallpox (1980) and rindepest (2011) have been eradicated so far. This is despite billions of dollars being poured into trying to eradicate diseases like polio and guinea worm. Perhaps a parallel to screwworm l is guinea worm, which should in theory be not that hard to eradicate given that humans are the main host, yet guinea worm still infects handfuls of people and animals in multiple countries despite us successfully reducing the global burden by 99.xx percent. We may well eradicate guinea worm soon, but it seems to me an easier task than this screwworm
2. This is a tropical parasite, with North and central America at the top of the range. The distribution map looks not so dissimilar to Malaria. This means that it is likely to be harder to eradicate closer to the equator. We talk about “shrinking the malaria map”, which means eradicating malaria from countries where it is less viable, to the south and the north of the equator. That’s why southern Europe, North Africa and Southern Africa can clear out their malaria, while most of sub-saharan africa currently can’t. The closer you get to the equator, the harder malaria becomes to eradicate. This may be similar
3. The current control method is expensive, sterile flies have to be produced in the hundreds of millions over a number of years. This would have to be performed over a huge land area accross many countries. To be fair this didn’t stop the USA and central America from successfully eradicating it there, so I don’t think this is a dealbreaker in and of itself
4. Screwworm infects many species as primary hosts, making complete eradication and surveilance much harder—especially among wild species.
5. Political will and conflict. A LOT of countries would need to come on board and there would need to be a LOT of co-operation. Would Venezuela get on board with this right now? A big reason that guinea worm and polio haven’t yet been eradicated, is that we lose the ability to vaccinate, treat and monitor in warzones. You would need a lot of co-operation and to have luck with lack of conflict in the region.
I’m not saying we shouldn’t invest a lot more money in controlling screwworm, and that we couldn’t reduce the population of worms by 95% or even 99% which could be a great investment, but looking seriously at the EV of complete eradication seems premature.
This looks like an exciting cause, but I’m not sure why we should have confidence that this screwworm can be completely eliminated in the near future. I know it has been eradicated from central America which is very impressive, but many diseases have been removed from much of the world (malaria, polio, measles, cholera etc.), yet are far from elimination. I have had a very cursory look at literature and I haven’t seen a strong argument or pathway as to why eradication might be probable—maybe someone could point me to it. There are a number of reasons this might be very, very difficult
(Note that I’m a global human health guy so basing my reasoning mainly on that, so I might be missing important things here)
1. Humanities track record so far (the best way to predict the future is look at the past). Only smallpox (1980) and rindepest (2011) have been eradicated so far. This is despite billions of dollars being poured into trying to eradicate diseases like polio and guinea worm. Perhaps a parallel to screwworm l is guinea worm, which should in theory be not that hard to eradicate given that humans are the main host, yet guinea worm still infects handfuls of people and animals in multiple countries despite us successfully reducing the global burden by 99.xx percent. We may well eradicate guinea worm soon, but it seems to me an easier task than this screwworm
2. This is a tropical parasite, with North and central America at the top of the range. The distribution map looks not so dissimilar to Malaria. This means that it is likely to be harder to eradicate closer to the equator. We talk about “shrinking the malaria map”, which means eradicating malaria from countries where it is less viable, to the south and the north of the equator. That’s why southern Europe, North Africa and Southern Africa can clear out their malaria, while most of sub-saharan africa currently can’t. The closer you get to the equator, the harder malaria becomes to eradicate. This may be similar
https://www.agriculture.gov.au/biosecurity-trade/pests-diseases-weeds/animal/ead-bulletin/ead-bulletin-109
3. The current control method is expensive, sterile flies have to be produced in the hundreds of millions over a number of years. This would have to be performed over a huge land area accross many countries. To be fair this didn’t stop the USA and central America from successfully eradicating it there, so I don’t think this is a dealbreaker in and of itself
4. Screwworm infects many species as primary hosts, making complete eradication and surveilance much harder—especially among wild species.
https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-020-04499-z
5. Political will and conflict. A LOT of countries would need to come on board and there would need to be a LOT of co-operation. Would Venezuela get on board with this right now? A big reason that guinea worm and polio haven’t yet been eradicated, is that we lose the ability to vaccinate, treat and monitor in warzones. You would need a lot of co-operation and to have luck with lack of conflict in the region.
I’m not saying we shouldn’t invest a lot more money in controlling screwworm, and that we couldn’t reduce the population of worms by 95% or even 99% which could be a great investment, but looking seriously at the EV of complete eradication seems premature.