Malaria Foundation International
Global Networking Against Malaria

Comments by C.F.Curtis on the
Malaria Control Handbook

(a publication of Physicians for Social Responsibility)

(The Handbook is a pdf file)

p.5, para.4, l.2-3: "some practitioners .. have been reluctant to totally eliminate DDT" – in view of the ~400 signatories of the Malaria Project/Malaria Foundation International letter this wording gives a misleading impression.

p.5, para.5, l.1 and 4-6: "good news for all … alternatives to DDT are available, .. proven and .. no more costly than .. DDT" - several of the attempts to justify this statement in this handbook are misleading.

p.9, l.4: "DDT weapon of choice against disease carrying mosquitoes…. This led to widespread contamination of fish, wildlife…" - no mention is made of the much larger quantities of DDT used out of doors in agriculture. Is there any convincing evidence that DDT used for indoor spraying has harmed outdoor wildlife?

p.9, para.3, l.4-5: "twenty workers .. levels of DDT that were ten times those of the general population… nervous system abnormalities (Abstract 16)" - the nearest that Abstract 16 comes to this is the statement that of 19 workers engaged in manufacture of HCH there were toxic symptoms in 90% of them and HCH concentrations in serum showed a ten-fold increase. DDT and the entirely different insecticide HCH appear to have been confused.

p.10, l.7-8: "Some research found … correlation between breast cancer and body burden of DDT but other studies found no such connection" – this wording would suggest an approximate balance between those finding a significant correlation and those who did not. However, as shown in the meta-analysis of Key and Reeves (1994, Brit Med J 308: 1520-1 and Hoyer et al, 1998, Lancet, 352: 1816-20), the ratio is actually 1 paper for and 6 against.

p.10, l.10: "workplace exposure to DDT found increase in … liver cancer .. (Abstracts 17-19)" – Abstract 17 contains the only mention of liver cancer and the data show that in workers on the Sardinian project not directly exposed to DDT there was as much elevation in this cancer compared with Italian norms as in those directly exposed.

p.57, l.1-2: "Environmental management of vector insects can dramatically reduce pesticide use and associated costs while contributing to sustained disease reduction (Abstracts 108-121)" – most of these abstracts make no mention of interventions to control vectors but are studies of larval ecology; of the few which are about mosquito control, most refer to old work in developed countries, with a few examples from India and China and with very few mentions of reducing pesticide usage or costs; there is nothing in these abstracts to support the view that proven, affordable non-insecticidal methods are available for controlling the African or South East Asian malaria problems; abstract 119 says that the role of bacterial toxins against disease vectors will be minor.

p.57, para.3: "larvivorous fish .. disease control programs in many countries (Abstract 117)" – abstract 117 is about vector ecology and does not mention the word "fish" – nor do the neighbouring abstracts.

p.57, para.4.: "Lagenidium fungus … (Abstract 113)" – abstract 113 is about control of nuisance mosquitoes in Californian ricefields – this is a very different situation from control of tropical vectors to a level that will impact on endemic malaria.

p.58, para.1: "Blue green algae … (Abstract 120)" – abstract 120 is about the subspecies of Bt which attacks Lepidoptera, not Bti which attacks mosquito larvae. If blue green algae are produced carrying Bti genes, would PSR think it wise to release this genetically manipulated strain, bearing in mind that, unlike GM cultivars, blue green algae are wild species, the release of which would be irrevocable.

p.65, l.6-8: "For example when people understand where disease-carrying mosquitoes breed they are more careful to change or remove their potential habitats". – only one of the 18 abstracts in section H mentions control of mosquito breeding – the rest are about drugs and nets. Abstract 129 mentions breeding site drainage in a program inspired by the Nicaraguan Sandinistas. However, this program was a package of measures including intensified chemotherapy. Is there evidence that the drainage contributed to the modest success that was achieved by this worthy effort? Now that the U.S. has succeeded in destroying the Sandinista regime, is it likely that a similar program would be set up and sustained on more than a demonstration level? Adequate control of larvae of rural anopheline vectors is much more difficult than that of the domestic breeding of Aedes and Culex, even for trained professionals.

p.82, l.9: "organically based pyrethroids" – pyrethroids are synthetic organic chemicals, as is DDT.

p.92, para.3, l.5-6: "the Holy Grail of a genetically modified mosquito incapable of transmitting malaria" – Plasmodium–refractory Anopheles have been selected years ago by conventional animal breeding methods – the reason that they have not been used is that there is no mechanism available reliably to drive the genes concerned into wild populations. Thus for affordable vector control without DDT we are left with insecticide treated nets (ITNs) which work well when provided free to whole communities (see abstracts in section E and other more recent work) so that the local vector population is greatly reduced. Whether they work when available only to the few people in a community able and willing to pay for them remains to be investigated, but the ideology that the poor should be made to pay for their protection from malaria has now become predominant. This was not the view from the 1940s to 1960s when many national programs provided house spraying freely to all houses in malarious areas with results that were even better than the best so far achieved by community-wide ITN programs (see http://scope.educ.washington.edu/research/malaria/index.html)

PSR letter, para.3, l.2: "WHO has taken an ever stronger stand" – this gives a misleading impression. At a major WHO meeting on vector control in 1993 I raised the points about DDT residues in South African breast milk, Wolff’s study on breast cancer and Garabrant’s data on pancreatic cancer. However, two consultant toxicologists concluded that there was not convincing evidence that DDT, as used indoors against malaria, was harmful to human health. Further research was recommended on these questions in the meeting report (see Med Vet Ent 8: 113 (1994)) but has not been done. The next WHO statement appears to have been the WHO Assembly resolution which was apparently passed without presentation of scientific data. It recognised DDT as a Persistent Organic Pollutant but also emphasised that the issue should be resolved taking into account the danger to public health of banning DDT without adequately replacing it. A meeting was organised by WHO in June 1999 to produce a DDT Action Plan but no report has yet been agreed on and printed. Instead an anodyne press release has been issued.



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