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Free insecticide for nets is cost effective
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References 1 Guyatt, H.L. and Snow R.W. (2002) The cost of not treating bednets. Trends Parasitol. 18, 12–16 2 Curtis, C.F. et al. (1998) A comparison of use of a pyrethroid either for house-spraying or for bednet treatment against malaria vectors. Trop. Med. Int. Health 3, 619–631 3 Maxwell, C.A. et al. (1999) Comparison of bednets impregnated with different pyrethroids for their impact on mosquitoes and on re-infection with malaria after clearance of pre-existing infections with chloroproguanil-dapsone. Trans. R. Soc. Trop. Med. Hyg. 93, 4–11 4 Sachs, J. et al. (2001) Macroeconomics and Health. Investing in Health for Economic Development; WHO (NLM classification WA30)
Free insecticide for nets is cost effective Response from Guyatt and Snow
The two issues raised by Curtis and Maxwell demand further clarification. First, how much does it really cost to deliver insecticide-treated bednets (ITNs) to communities? Second, should they be provided free-of-charge to at-risk groups? Presenting the incremental financial costs of delivering insecticide to a few villages, where a research program has been operating for many years, can be misleading and different to the costs of operating in an entire district or at a national level. The cost of implementation is an important variable in the evaluation process and it is crucial that the costs are comprehensive, accounting for all resources consumed. When evaluating many interventions, research costs are often separated from the implementation costs, although these costs inherently support the delivery process. For example, the costs of expatriate salaries, field-workers and surveillance systems are rarely considered. These hidden costs are often excluded from analyses of other donor-supported, operational projects. For example, if only the costs directly attributable to an ITN and its delivery are considered for a non-governmental organization (NGO)managed program in Kenya, the estimated cost per ITN is US$8.42 [1]. However, when the external costs are included (basically, the amount of money received from donors), the cost per ITN is closer to US$30 [1]. This is consistent with other donor- or †Snow, R.W. et al. (2001) Strategic development and
activity for Roll Back Malaria in Kenya 1998–2000. Report prepared for Ministry of Health, Kenya and UNICEF Kenya country office, March 2001. http://parasites.trends.com
TRENDS in Parasitology Vol.18 No.5 May 2002
research-funded project costs in Kenya (US$45 per AMREF employer-based net and US$29 per CDC research project net)†. We agree that precise details are required to provide robust cost-effectiveness analyses, but disagree with the estimates for their research villages in Tanzania because they fall prey to the general tendency to be exclusive rather than inclusive of the true delivery costs. Curtis and Maxwell also highlight an important issue that we were at pains to raise as a controversial area in the original paper: whether ITNs should be a free public health service. When better quality, inclusive cost-data become available from the projectapproach to delivering ITN services, there will be a growing recognition that ensuring maximal coverage of this intervention will not be cheap. We believe that this intervention should be delivered free-ofcharge to those most at-risk of the burden posed by malaria in Africa. Most of Africa’s population lives below the absolute poverty line. The African Heads of State have pleaded with the global community to consider this as an option to protect the equity of healthservice provision in their respective countries. Some donors and research scientists have resisted this position. What is clear is that the real costs to the donor community of maximizing equitable coverage of ITNs will be one of the most persuasive evidencebased criteria upon which to judge who is right in the debate on free bednets. Helen L. Guyatt* Robert W. Snow Wellcome Trust Research Labs/KEMRI, PO Box 43640 Nairobi, Kenya. *e-mail: [email protected] Reference 1 Guyatt, H.L. et al. (2002) A comparative cost analysis of insecticide treated nets and indoor residual spraying in highland Kenya. Health Policy Plan. 17, 144–153
Helminthiasis: new medical significance Dan Colley et al. [1] suggested that an ‘Affirmative Action for Worms’ researchfunding program should be established. Their idea is aimed at reversing ‘the current downward spiral of research’ in the field of medical helminthology. In supporting this proposal, Paul Hagan accurately comments: ‘The essential shift of focus to HIV/AIDS…tuberculosis and
205
malaria could be responsible for the decline in helminth research’ [2]. I wish to make a tongue-in-cheek observation that research on HIV/AIDS, TB, malaria and allergy should become part of research on helminthiasis. Worm infestations diminish the efficacy of certain types of vaccine against various diseases, including TB [3] and, perhaps, HIV/AIDS and malaria [4–6]. Deworming before vaccination has been shown (for vaccines against more than one non-helminthic disease) to enhance the post-vaccination immune response, but additional studies are urgently needed [3,5]. Moreover, it has been suggested that ascariasis is associated with protection from cerebral malaria [6]; and Bentwich’s hypothesis [7,8] is that the immunological consequences of various helminthic infestations are likely to predispose individuals to infection with HIV and Mycobacterium tuberculosis and/or accelerate progression of clinical illness caused by these two organisms. Lastly, there appear to be important, interesting and puzzling interactions between atopy and helminthiasis, which are only now starting to be investigated properly [9,10]. The considerable public health significance of all these possible correlations and new findings is self-evident and provides support for the program suggested by Colley et al. [1,2]. Miles B. Markus Consulting Services International, 27 Old Gloucester Street, London, UK WC1N 3XX. e-mail: [email protected] References 1 Colley, D.G. et al. (2001) Medical helminthology in the 21st Century. Science 293, 1437–1438 2 Hagan, P. (2001) This wormless world. Trends Parasitol. 17, 569 3 Markus, M.B. (2001) Worms and tuberculosis vaccines. Trends Microbiol. 9, 474 4 Markus, M.B. and Fincham, J.E. (2001) Helminthic infection and HIV vaccine trials. Science 291, 46–47 5 Markus, M.B. and Fincham, J.E. (2001) Helminthiasis and HIV vaccine efficacy. Lancet 357, 1799 6 Nacher, M. (2001) Malaria vaccine trials in a wormy world. Trends Parasitol. 17, 563–565 7 Bundy, D. et al. (2000) Good worms or bad worms: do worm infections affect the epidemiological patterns of other diseases? Parasitol. Today 16, 273–274 8 Markus, M.B. and Fincham, J.E. (2000) Mbeki and AIDS in Africa. Science 288, 2131 9 Yazdanbakhsh, M. et al. (2001) Th2 responses without atopy: immunoregulation in chronic helminth infections and reduced allergic disease. Trends Immunol. 22, 372–377 10 Markus, M.B. (2001) Worms and allergy. Trends Immunol. 22, 598–599
1471-4922/02/$ – see front matter © 2002 Elsevier Science Ltd. All rights reserved.
References 1 Guyatt, H.L. and Snow R.W. (2002) The cost of not treating bednets. Trends Parasitol. 18, 12–16 2 Curtis, C.F. et al. (1998) A comparison of use of a pyrethroid either for house-spraying or for bednet treatment against malaria vectors. Trop. Med. Int. Health 3, 619–631 3 Maxwell, C.A. et al. (1999) Comparison of bednets impregnated with different pyrethroids for their impact on mosquitoes and on re-infection with malaria after clearance of pre-existing infections with chloroproguanil-dapsone. Trans. R. Soc. Trop. Med. Hyg. 93, 4–11 4 Sachs, J. et al. (2001) Macroeconomics and Health. Investing in Health for Economic Development; WHO (NLM classification WA30)
Free insecticide for nets is cost effective Response from Guyatt and Snow
The two issues raised by Curtis and Maxwell demand further clarification. First, how much does it really cost to deliver insecticide-treated bednets (ITNs) to communities? Second, should they be provided free-of-charge to at-risk groups? Presenting the incremental financial costs of delivering insecticide to a few villages, where a research program has been operating for many years, can be misleading and different to the costs of operating in an entire district or at a national level. The cost of implementation is an important variable in the evaluation process and it is crucial that the costs are comprehensive, accounting for all resources consumed. When evaluating many interventions, research costs are often separated from the implementation costs, although these costs inherently support the delivery process. For example, the costs of expatriate salaries, field-workers and surveillance systems are rarely considered. These hidden costs are often excluded from analyses of other donor-supported, operational projects. For example, if only the costs directly attributable to an ITN and its delivery are considered for a non-governmental organization (NGO)managed program in Kenya, the estimated cost per ITN is US$8.42 [1]. However, when the external costs are included (basically, the amount of money received from donors), the cost per ITN is closer to US$30 [1]. This is consistent with other donor- or †Snow, R.W. et al. (2001) Strategic development and
activity for Roll Back Malaria in Kenya 1998–2000. Report prepared for Ministry of Health, Kenya and UNICEF Kenya country office, March 2001. http://parasites.trends.com
TRENDS in Parasitology Vol.18 No.5 May 2002
research-funded project costs in Kenya (US$45 per AMREF employer-based net and US$29 per CDC research project net)†. We agree that precise details are required to provide robust cost-effectiveness analyses, but disagree with the estimates for their research villages in Tanzania because they fall prey to the general tendency to be exclusive rather than inclusive of the true delivery costs. Curtis and Maxwell also highlight an important issue that we were at pains to raise as a controversial area in the original paper: whether ITNs should be a free public health service. When better quality, inclusive cost-data become available from the projectapproach to delivering ITN services, there will be a growing recognition that ensuring maximal coverage of this intervention will not be cheap. We believe that this intervention should be delivered free-ofcharge to those most at-risk of the burden posed by malaria in Africa. Most of Africa’s population lives below the absolute poverty line. The African Heads of State have pleaded with the global community to consider this as an option to protect the equity of healthservice provision in their respective countries. Some donors and research scientists have resisted this position. What is clear is that the real costs to the donor community of maximizing equitable coverage of ITNs will be one of the most persuasive evidencebased criteria upon which to judge who is right in the debate on free bednets. Helen L. Guyatt* Robert W. Snow Wellcome Trust Research Labs/KEMRI, PO Box 43640 Nairobi, Kenya. *e-mail: [email protected] Reference 1 Guyatt, H.L. et al. (2002) A comparative cost analysis of insecticide treated nets and indoor residual spraying in highland Kenya. Health Policy Plan. 17, 144–153
Helminthiasis: new medical significance Dan Colley et al. [1] suggested that an ‘Affirmative Action for Worms’ researchfunding program should be established. Their idea is aimed at reversing ‘the current downward spiral of research’ in the field of medical helminthology. In supporting this proposal, Paul Hagan accurately comments: ‘The essential shift of focus to HIV/AIDS…tuberculosis and
205
malaria could be responsible for the decline in helminth research’ [2]. I wish to make a tongue-in-cheek observation that research on HIV/AIDS, TB, malaria and allergy should become part of research on helminthiasis. Worm infestations diminish the efficacy of certain types of vaccine against various diseases, including TB [3] and, perhaps, HIV/AIDS and malaria [4–6]. Deworming before vaccination has been shown (for vaccines against more than one non-helminthic disease) to enhance the post-vaccination immune response, but additional studies are urgently needed [3,5]. Moreover, it has been suggested that ascariasis is associated with protection from cerebral malaria [6]; and Bentwich’s hypothesis [7,8] is that the immunological consequences of various helminthic infestations are likely to predispose individuals to infection with HIV and Mycobacterium tuberculosis and/or accelerate progression of clinical illness caused by these two organisms. Lastly, there appear to be important, interesting and puzzling interactions between atopy and helminthiasis, which are only now starting to be investigated properly [9,10]. The considerable public health significance of all these possible correlations and new findings is self-evident and provides support for the program suggested by Colley et al. [1,2]. Miles B. Markus Consulting Services International, 27 Old Gloucester Street, London, UK WC1N 3XX. e-mail: [email protected] References 1 Colley, D.G. et al. (2001) Medical helminthology in the 21st Century. Science 293, 1437–1438 2 Hagan, P. (2001) This wormless world. Trends Parasitol. 17, 569 3 Markus, M.B. (2001) Worms and tuberculosis vaccines. Trends Microbiol. 9, 474 4 Markus, M.B. and Fincham, J.E. (2001) Helminthic infection and HIV vaccine trials. Science 291, 46–47 5 Markus, M.B. and Fincham, J.E. (2001) Helminthiasis and HIV vaccine efficacy. Lancet 357, 1799 6 Nacher, M. (2001) Malaria vaccine trials in a wormy world. Trends Parasitol. 17, 563–565 7 Bundy, D. et al. (2000) Good worms or bad worms: do worm infections affect the epidemiological patterns of other diseases? Parasitol. Today 16, 273–274 8 Markus, M.B. and Fincham, J.E. (2000) Mbeki and AIDS in Africa. Science 288, 2131 9 Yazdanbakhsh, M. et al. (2001) Th2 responses without atopy: immunoregulation in chronic helminth infections and reduced allergic disease. Trends Immunol. 22, 372–377 10 Markus, M.B. (2001) Worms and allergy. Trends Immunol. 22, 598–599
1471-4922/02/$ – see front matter © 2002 Elsevier Science Ltd. All rights reserved.