Intermittent Preventive Treatment
Antimalarial drugs have been used in various ways to prevent malaria in the resident populations of endemic areas for nearly 100 years. The primary aim of most early studies was to interrupt transmission. Chemoprophylaxis is highly effective in reducing mortality and morbidity from malaria in young children and pregnant women living in endemic areas, but is difficult to sustain and, in some studies, has impaired the development of naturally acquired immunity.
Intermittent preventive treatment (IPT) describes the administration of a full therapeutic course of an anti-malarial to at risk subjects at specified times regardless of whether they are infected or not. IPT differs from chemoprophylaxis, which aims to sustain blood levels above the mean inhibitory concentration for a prolonged period, in producing protective drug concentrations for only short periods of time separated by periods when drug concentrations are below the level necessary to inhibit parasite growth. IPT is now a recommended approach to the prevention of malaria in pregnancy (sometimes called IPTp), and is administered at antenatal clinic visits. IPT is being explored as a potential way of preventing malaria in infants (IPTi), potentially linked with routine immunisation schedules. IPT in young children (IPTc) is the subject of new research.
Sulfadoxine-pyrimethamine (SP) is the drug that has been used most widely for IPT in both pregnant women and children, but it is not known whether IPT achieves its effect primarily by elimination of already present parasites or through the long-acting, prophylactic effect of SP. However, because of rapidly increasing resistance, it is unlikely that IPT in pregnancy with SP will in future remain as effective as it was in East Africa 5-10 years ago when first evaluated. Amodiaquine and SP are being tested for IPT in infants. More effective antimalarial drugs such as artemether-lumefantrine and dihydroartemisinin-piperaquine should be evaluated for IPT in both low- and high-transmission settings.
Factors that determine whether IPT should be used in certain populations include: (1) whether intermittent preventive treatment adds to the protection afforded by other control measures such as insecticide-treated mosquito nets; (2) whether an effective and sustainable delivery system can be found; (3) choice of drug to be used; (4) optimum timing of drug administration; (5) the requisite interval between treatments. The potential benefits of intermittent preventive treatment in children are substantial; more research is needed to determine if this is a practical approach to malaria control.
- Intermittent preventive treatment (IPT) with sulfadoxine-pyrimethamine is recommended for use in areas with high levels of malaria transmission.
- The duration of post treatment prophylaxis is likely to be an important determinant of the benefit of IPT.
- More effective antimalarial drugs need to be evaluated for IPT in both low- and high-transmission settings.
* Egan A, Crawley J and Schellenberg D. (September 2005) Editorial: Intermittent preventive treatment for malaria control in infants: moving towards evidence-based policy and public health action Tropical Medicine and International Health 10 (9), 815-817.
* O'Meara W P, Breman J G and F Ellis McKenzie. (July 2005) The promise and potential challenges of intermittent preventive treatment for malaria in infants. Malaria Journal 4,33.
* White N J (2005) Intermittent presumptive treatment for malaria. PLoS Med 2(1) 3.
* Schellenberg D, Cisse B, Menendez C. (2006) The IPTi Consortium:research for policy and action. Trends in Parasitology 2006 Jul;22(7):296-300.
* Coulibaly, S.O., Nezien, D., Traore, S., Kone, B. & Magnussen, P. (2006) Therapeutic efficacy of sulphadoxine-pyrimethamine and chloroquine for the treatment of uncomplicated malaria in pregnancy in Burkina Faso. Malaria Journal 5: 49.
* Mubyazi, G., Bloch, P., Kamugisha, M., Kitua, A. & Ijumba, J. (2006) Intermittent preventive treatment of malaria during pregnancy: a qualitative study of knowledge, attitudes and practices of district health managers, antenatal care staff and pregnant women in Korogwe District, north-eastern Tanzania. Malaria Journal 4: 31.