- Email: [email protected]
Eliminating neglected diseases in Africa
Correspondence
We declare that we have no conflict of interest.
*Omar Aftab, Fahd Khalid Syed [email protected] Aga Khan University Hospital, Stadium Road, PO Box 3500, Karachi 74800, Pakistan 1
2
3
4
Kolaczinski J, Graham K, Fahim A, Brooker S, Rowland M. Malaria control in Afghanistan: progress and challenges. Lancet early online publication Feb 1, 2005. Adjuik M, Babiker A, Garner P, Olliaro P, Taylor W, White N. Artesunate combinations for treatment of malaria: meta-analysis. Lancet 2004; 363: 9–17. Muheki C, McIntyre D, Barnes KI. Artemisininbased combination therapy reduces expenditure on malaria treatment in KwaZulu Natal, South Africa. Trop Med Int Health 2004; 9: 959–66. Caulfield LE, Richard SA, Black RE. Undernutrition as an underlying cause of malaria morbidity and mortality in children less than five years old. Am J Trop Med Hyg 2004; 71: 55–63.
Eliminating neglected diseases in Africa We welcome the comments by Alan Fenwick and colleagues (Mar 19, p 1029)1 who highlight a pro-poor health intervention in Africa based on the use of four drugs (praziquantel, albendazole, ivermectin, and azithromycin) to eliminate schistosomiasis, lymphatic filariasis, onchocerciasis, hookworm, ascariasis, trichuriasis, and trachoma. Clearly, advocacy for tackling the “neglected seven” in Africa is long overdue. However, we wish to temper their comments by pointing out that there are more than 500 million cases of soiltransmitted helminth infections in subwww.thelancet.com Vol 365 June 18, 2005
Saharan Africa, including 198 million cases of hookworm, 173 million of ascariasis, and 162 million of trichuriasis.2 Cure rates for trichuriasis and hookworm with a single dose of benzimidazoles are low, especially for highly infected individuals; ivermectin lacks efficacy for treating hookworm; and rapid reinfection can occur after treatment, often necessitating up to three retreatments annually.3 Thus the question is not simply one of treatment, but of sustainable treatment and retreatment. Programmes designed to control morbidity and not to eliminate soil-transmitted helminth infections require a long-term commitment and are logistically complex to sustain over the required time period. An equally worrying limitation of repeated chemotherapy is the potential for drug resistance; for over 15 years, resistance to anthelmintics in nematode parasites of domestic livestock, often exceeding 50%, has been reported in all parts of the world. Anthelmintic resistance becomes apparent only when reversion to susceptibility is no longer possible. The occurrence of rapid drug resistance is especially worrying given the scale of planned interventions. To exacerbate these concerns, there has been little incentive for pharmaceutical companies to develop new anthelmintic compounds. In short, there are no other drug options should anthelmintic resistance occur. Therefore, drug use and efficacy should be monitored to face the threat of drug resistance.4 Concurrent with monitoring, support should be provided for parallel efforts to develop and assess new tools for control. The Human Hookworm Vaccine Initiative, a public-private partnership sponsored by the Sabin Vaccine Institute, has developed a first-generation anthelmintic vaccine that will undergo clinical trials.5 Similarly, there is an initiative underway to develop a vaccine for schistosomiasis. Such vaccines linked to chemotherapy would not only reduce morbidity but also lessen the need for continuous intervention, thereby reducing the drug treatment
cycle and extending the viability of this option. In the long term, improved access to clean water and sanitation will be needed to tackle many of the neglected diseases in sub-Saharan Africa. In the early 1960s, there was widespread optimism that the 50 000 cases of malaria remaining in India would soon vanish, and malaria would be eradicated. The rising costs of dichlorodiphenyltrichloroethane (DDT) coupled with emerging DDT and chloroquine resistance subsequently wiped out almost all gains made in this regard. Such a tale is a caution to attempts to eliminate the neglected seven in Africa. We agree with Fenwick and colleagues that the four drugs mentioned should be used aggressively to control morbidity and reduce disease burden. At the same time, we are confident that they would agree with the urgent need for continuing parallel efforts to research and develop new control tools, including drugs, diagnostics, and vaccines. PH is a co-inventor on an international patent application “Hookworm Vaccine”, which was filed to ensure that the vaccine is not blocked from being made available to developing countries. No financial benefit is anticipated.
*Peter Hotez, Jeff Bethony, Simon Brooker, Marco Albonico [email protected] Department of Microbiology and Tropical Medicine, George Washington University, 2300 Eye Street NW, Washington, DC 20037, USA (PH, JB); Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK (SB); and Ivo de Carneri Foundation, Milan, Italy (MA) 1
2
3
4
5
Fenwick A, Molyneux D, Nantulya V. Achieving the millennium development goals. Lancet 2005; 365: 1029–30. de Silva NR, Brooker S, Hotez PJ, Montresor A, Engels D, Savioli L. Soil-transmitted helminth infections: updating the global picture. Trends Parasitol 2003; 19: 547–51. World Health Organization. Prevention and control of schistosomiasis and soil-transmitted helminthiasis. Report of a WHO Expert Committee. WHO Tech Rep Ser 912. Geneva: WHO, 2002: 35. Albonico M, Engels D, Savioli L. Monitoring drug efficacy and early detection of drug resistance in human soil-transmitted nematodes: a pressing public health agenda for helminth control. Int J Parasitol 2004; 34: 1205–10. Brooker S, Bethony JM, Rodrigues LC, Alexander N, Geiger SM, Hotez PJ. Epidemiologic, immunologic and practical considerations in developing a human hookworm vaccine. Expert Rev Vaccines 2005; 4: 35–50.
Rights were not granted to include this image in electronic media. Please refer to the printed journal.
2089
Science Photo Library
dren would reduce morbidity and mortality from malaria. It would go a long way towards buttressing their immunity and protecting them from many other ailments besides malaria. Deficiencies in micronutrients such as vitamin A and zinc have been specifically implicated in the increasing burden of malaria in the paediatric age-group.4 A combined programme on nutrition and malaria incorporated into the primary health-care package would greatly improve Afghanistan’s chances of winning this longstanding war against malaria.
We declare that we have no conflict of interest.
*Omar Aftab, Fahd Khalid Syed [email protected] Aga Khan University Hospital, Stadium Road, PO Box 3500, Karachi 74800, Pakistan 1
2
3
4
Kolaczinski J, Graham K, Fahim A, Brooker S, Rowland M. Malaria control in Afghanistan: progress and challenges. Lancet early online publication Feb 1, 2005. Adjuik M, Babiker A, Garner P, Olliaro P, Taylor W, White N. Artesunate combinations for treatment of malaria: meta-analysis. Lancet 2004; 363: 9–17. Muheki C, McIntyre D, Barnes KI. Artemisininbased combination therapy reduces expenditure on malaria treatment in KwaZulu Natal, South Africa. Trop Med Int Health 2004; 9: 959–66. Caulfield LE, Richard SA, Black RE. Undernutrition as an underlying cause of malaria morbidity and mortality in children less than five years old. Am J Trop Med Hyg 2004; 71: 55–63.
Eliminating neglected diseases in Africa We welcome the comments by Alan Fenwick and colleagues (Mar 19, p 1029)1 who highlight a pro-poor health intervention in Africa based on the use of four drugs (praziquantel, albendazole, ivermectin, and azithromycin) to eliminate schistosomiasis, lymphatic filariasis, onchocerciasis, hookworm, ascariasis, trichuriasis, and trachoma. Clearly, advocacy for tackling the “neglected seven” in Africa is long overdue. However, we wish to temper their comments by pointing out that there are more than 500 million cases of soiltransmitted helminth infections in subwww.thelancet.com Vol 365 June 18, 2005
Saharan Africa, including 198 million cases of hookworm, 173 million of ascariasis, and 162 million of trichuriasis.2 Cure rates for trichuriasis and hookworm with a single dose of benzimidazoles are low, especially for highly infected individuals; ivermectin lacks efficacy for treating hookworm; and rapid reinfection can occur after treatment, often necessitating up to three retreatments annually.3 Thus the question is not simply one of treatment, but of sustainable treatment and retreatment. Programmes designed to control morbidity and not to eliminate soil-transmitted helminth infections require a long-term commitment and are logistically complex to sustain over the required time period. An equally worrying limitation of repeated chemotherapy is the potential for drug resistance; for over 15 years, resistance to anthelmintics in nematode parasites of domestic livestock, often exceeding 50%, has been reported in all parts of the world. Anthelmintic resistance becomes apparent only when reversion to susceptibility is no longer possible. The occurrence of rapid drug resistance is especially worrying given the scale of planned interventions. To exacerbate these concerns, there has been little incentive for pharmaceutical companies to develop new anthelmintic compounds. In short, there are no other drug options should anthelmintic resistance occur. Therefore, drug use and efficacy should be monitored to face the threat of drug resistance.4 Concurrent with monitoring, support should be provided for parallel efforts to develop and assess new tools for control. The Human Hookworm Vaccine Initiative, a public-private partnership sponsored by the Sabin Vaccine Institute, has developed a first-generation anthelmintic vaccine that will undergo clinical trials.5 Similarly, there is an initiative underway to develop a vaccine for schistosomiasis. Such vaccines linked to chemotherapy would not only reduce morbidity but also lessen the need for continuous intervention, thereby reducing the drug treatment
cycle and extending the viability of this option. In the long term, improved access to clean water and sanitation will be needed to tackle many of the neglected diseases in sub-Saharan Africa. In the early 1960s, there was widespread optimism that the 50 000 cases of malaria remaining in India would soon vanish, and malaria would be eradicated. The rising costs of dichlorodiphenyltrichloroethane (DDT) coupled with emerging DDT and chloroquine resistance subsequently wiped out almost all gains made in this regard. Such a tale is a caution to attempts to eliminate the neglected seven in Africa. We agree with Fenwick and colleagues that the four drugs mentioned should be used aggressively to control morbidity and reduce disease burden. At the same time, we are confident that they would agree with the urgent need for continuing parallel efforts to research and develop new control tools, including drugs, diagnostics, and vaccines. PH is a co-inventor on an international patent application “Hookworm Vaccine”, which was filed to ensure that the vaccine is not blocked from being made available to developing countries. No financial benefit is anticipated.
*Peter Hotez, Jeff Bethony, Simon Brooker, Marco Albonico [email protected] Department of Microbiology and Tropical Medicine, George Washington University, 2300 Eye Street NW, Washington, DC 20037, USA (PH, JB); Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK (SB); and Ivo de Carneri Foundation, Milan, Italy (MA) 1
2
3
4
5
Fenwick A, Molyneux D, Nantulya V. Achieving the millennium development goals. Lancet 2005; 365: 1029–30. de Silva NR, Brooker S, Hotez PJ, Montresor A, Engels D, Savioli L. Soil-transmitted helminth infections: updating the global picture. Trends Parasitol 2003; 19: 547–51. World Health Organization. Prevention and control of schistosomiasis and soil-transmitted helminthiasis. Report of a WHO Expert Committee. WHO Tech Rep Ser 912. Geneva: WHO, 2002: 35. Albonico M, Engels D, Savioli L. Monitoring drug efficacy and early detection of drug resistance in human soil-transmitted nematodes: a pressing public health agenda for helminth control. Int J Parasitol 2004; 34: 1205–10. Brooker S, Bethony JM, Rodrigues LC, Alexander N, Geiger SM, Hotez PJ. Epidemiologic, immunologic and practical considerations in developing a human hookworm vaccine. Expert Rev Vaccines 2005; 4: 35–50.
Rights were not granted to include this image in electronic media. Please refer to the printed journal.
2089
Science Photo Library
dren would reduce morbidity and mortality from malaria. It would go a long way towards buttressing their immunity and protecting them from many other ailments besides malaria. Deficiencies in micronutrients such as vitamin A and zinc have been specifically implicated in the increasing burden of malaria in the paediatric age-group.4 A combined programme on nutrition and malaria incorporated into the primary health-care package would greatly improve Afghanistan’s chances of winning this longstanding war against malaria.