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• A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Jan 20 2013: Dear Susan,
  
  Great to see that schoolers are discussing my work - thanks. To be honest, I have no idea if dead mosquitoes are repellent to other mosquitoes. I know from past field work that dead tsetse flies (especially when wet and rotting) produced a scent that repelled other tsetse flies and reduced trap catches. We resolved this problem by adding small holes to the trap bags so that ants could access the dead flies and eat them. 'Feed tsetse to the ants' then became a slogan in this Kenyan project. The pill is not only killing mosquitoes when ingested by humans, and I believe that many other blood-feeding insects can also be killed by it.
  
  Needless to say I would be very keen to hear the outcome of what the students came up with. Perhaps some of these ideas are worth pursuing! Best of luck,
  Bart

• A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Dec 27 2012: Believe it or not, dogs are currently being used in the wards (of at least one Dutch hospital) to sniff out patients that are infected with Clostridium difficile, a highly infectious bacteria causing diarrhoea and complicating patient care. The dog is trained not to bark or do anything abnormal - instead, if it smells an infected patient it will merely sit down at the bedside.
  
  I do not see why it would be a problem to sniff out people carrying malaria parasites. A recent study from Africa showed that 20-50% of all infections of mosquitoes (when taking blood) occurs from humans that do not show any symptoms of malaria and where microscopy will not be sensitive enough to detect the parasites (in a blood film).
  
  I am convinced that the sensitive nose of dogs may provide an ideal solution here. Research has shown that mosquitoes can discriminate between children carrying different stages of malaria parasites on the basis of their smell. If mosquitoes can do it, then why not dogs?
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  A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Dec 17 2012: Dear Elisabeth,
  
  Very interesting to hear that your father was involved in this campaign. Note though that 'failure' is a big word. The campaign that lasted from 1955-1969 freed major parts of the world of the scourge of malaria. Europe, the USA, Russia, Australia, the Caribbean, Taiwan, and so on, all saw their malaria disappear following intense operations. If anything, to me this is proof that it can be done. Where 'we' did fail was in the tropics, largely because these were not even included in the campaign (notably Africa) as it was considered to be logistically impossible. But things have changed meanwhile and many African countries now have infrastructure and resources that could make an attempt to eliminate worthwhile. In fact, I believe that it is the only way forward, as otherwise evolution will merely make our efforts useless when parasites and mosquitoes develop resistance to the drugs and insecticides we use against them, respectively...

• A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Nov 11 2012: Please see discussion on the pill below in the comments raised by others. If questions remain after that, just let me know.

• A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Nov 11 2012: Dear Maria,
  Please check extensive conversation on this topic below. If you have questions remaining, please let me know.
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  A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Sep 14 2012: By and large I agree with your views - chemicals are more often than not giving us problems, be it in the form of insecticides or drugs. Regretfully there was no time during my talk to focus on another major development that my colleagues and I are working on: the use of entomopathogenic fungi to kill mosquitoes. This is pure biological control that we are trying to bring to the forefront in mosquito control.
  
  The great thing about these fungi (which occur around the world in the soil) is that they don't kill the mosquito immediately upon contact - this usually takes 8-10 days. By killing mosquitoes later in life we allow them to reproduce in the meantime which sharply reduces the chance of resistance kicking in. Resistance normally comes with a fitness cost, so any genotype that would confer resistance would only benefit older individuals in the population and be a burden to the rest of that population. Hence (as has been modeled) the chance of resistance developing against these 'late-in-life' killing approaches is extremely low.
  
  Bringing fungi to the real world of malaria control is a different matter though. There are many sceptics that are believing in chemical approaches as if nothing else exists. There's the lobbying from the pesticide industry, and there's clearance issues (with WHO's Pesticide Evaluation Scheme) which takes a long time.
  
  In agriculture, the shift away from chemicals to biologicals has been ongoing for decades, with many fantastic success stories. Regretfully, in public health, we still have to learn some lessons....

• A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Sep 4 2012: The process you refer to is known as behavioural resistance, whereby the part of the population that feeds on hosts other than humans will have a selective advantage and proliferate. However, in terms of malaria, this would not be a bad thing. If a whole new mosquito population would emerge that hardly fed on humans, than transmission of malaria would largely cease. In Africa, some of the most important malaria mosquito species feed almost exclusively on human blood. As for the pill, like with most drugs, resistance is an issue to watch out for - and hard to stop from kicking in at some stage. Until that happens, it may hopefully play a big role in integrated control/elimination campaigns though...

• A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Aug 22 2012: Dear Robert, Thanks for your kind words - may I suggest you sign up for MalariaWorld (free), see www.malariaworld.org so that we can discuss more and you can see what other professionals have to say and do in the field of malaria.

• A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Jul 9 2012: @Ed - interesting idea, and has been tried before. Not so much by adding a drug to drinking water, but to add it to table salt. In the 1960s, trials were undertaken to add anti-malarial drugs to table salt (in Papua New Guinea) as a way to practice mass drug administration. It faltered because not everyone was taking enough salt to really clear parasites from the body. Worse, in low concentrations it stimulated the development of parasite resistance to chloroquine. So I would be reluctant to add it to drinking water for the same reason. Another issue today is that you cannot just add drugs...you'll need informed consent before you can administer drugs or vaccines, which cannot be done when adding it to water...
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  A reply on Talk: Bart Knols: Cheese, dogs and a pill to kill mosquitoes and end malaria

  Jul 3 2012: @Adrian & Amy - thanks for these interesting questions.
  
  Mosquitoes that have taken blood will normally rest for a period of 2-3 days (as part of what is called the gonotrophic cycle), during which time they will not feed on other humans or sources of blood and will certainly not be laying eggs (that's what they use the blood for, to transform it into eggs).
  
  So even if the drug would kill within a period of 24 hours, it would still be OK....