Single low-dose primaquine for blocking transmission of Plasmodium falciparum malaria - a proposed model-derived age-based regimen for sub-Saharan Africa.

BACKGROUND: In 2012, the World Health Organization recommended blocking the transmission of Plasmodium falciparum with single low-dose primaquine (SLDPQ, target dose 0.25 mg base/kg body weight), without testing for glucose-6-phosphate dehydrogenase deficiency (G6PDd), when treating patients with uncomplicated falciparum malaria. We sought to develop an age-based SLDPQ regimen that would be suitable for sub-Saharan Africa. METHODS: Using data on the anti-infectivity efficacy and tolerability of primaquine (PQ), the epidemiology of anaemia, and the risks of PQ-induced acute haemolytic anaemia (AHA) and clinically significant anaemia (CSA), we prospectively defined therapeutic-dose ranges of 0.15-0.4 mg PQ base/kg for children aged 1-5 years and 0.15-0.5 mg PQ base/kg for individuals aged ≥6 years (therapeutic indices 2.7 and 3.3, respectively). We chose 1.25 mg PQ base for infants aged 6-11 months because they have the highest rate of baseline anaemia and the highest risks of AHA and CSA. We modelled an anthropometric database of 661,979 African individuals aged ≥6 months (549,127 healthy individuals, 28,466 malaria patients and 84,386 individuals with other infections/illnesses) by the Box-Cox transformation power exponential and tested PQ doses of 1-15 mg base, selecting dosing groups based on calculated mg/kg PQ doses. RESULTS: From the Box-Cox transformation power exponential model, five age categories were selected: (i) 6-11 months (n = 39,886, 6.03%), (ii) 1-5 years (n = 261,036, 45.46%), (iii) 6-9 years (n = 20,770, 3.14%), (iv) 10-14 years (n = 12,155, 1.84%) and (v) ≥15 years (n = 328,132, 49.57%) to receive 1.25, 2.5, 5, 7.5 and 15 mg PQ base for corresponding median (1st and 99th centiles) mg/kg PQ base of: (i) 0.16 (0.12-0.25), (ii) 0.21 (0.13-0.37), (iii) 0.25 (0.16-0.38), (iv) 0.26 (0.15-0.38) and (v) 0.27 (0.17-0.40). The proportions of individuals predicted to receive optimal therapeutic PQ doses were: 73.2 (29,180/39,886), 93.7 (244,537/261,036), 99.6 (20,690/20,770), 99.4 (12,086/12,155) and 99.8% (327,620/328,132), respectively. CONCLUSIONS: We plan to test the safety of this age-based dosing regimen in a large randomised placebo-controlled trial (ISRCTN11594437) of uncomplicated falciparum malaria in G6PDd African children aged 0.5 - 11 years. If the regimen is safe and demonstrates adequate pharmacokinetics, it should be used to support malaria elimination.

Monitoring the efficacy of artemether-lumefantrine for the treatment of uncomplicated malaria in Malawian children.

BACKGROUND: The resistance of malaria parasites to sulphadoxine-pyrimethamine (SP) in 2007 led to the Malawi Ministry of Health changing to artemether-lumefantrine (AL) as first-line for uncomplicated malaria treatment. This study determined the efficacy and safety of AL for the treatment of uncomplicated Plasmodium falciparum malaria among six to 59 months old Malawian children. METHODS: This was a prospective study of children six to 59 months old treated with AL after presenting with uncomplicated malaria in the six health facilities in Malawi. The children were followed up on days 1, 2, 3, 7, 14, 21 and 28 days post-treatment and assessed for clinical and parasitological responses. The Kaplan Meier survival estimate was used to measure the efficacy of AL by calculating the cumulative risk of failure at day 28. RESULTS: A total of 322 children were recruited into the study across the six sites. The overall intention-to-treat (ITT) polymerase chain reaction (PCR)-corrected cure rate was 93.4%. Per protocol overall PCR-corrected cure rates for the study sites were; Karonga 98.0%, Kawale 97.4%, Machinga 90.2%, Mangochi 95.4% and Rumphi 91.3%. Nkhotakota study site had the lowest cure rate of 78.0%. CONCLUSIONS: There is evidence of good efficacy of AL in Malawi notwithstanding geographical contrasts and this supports the continued use of AL as the first-line treatment for uncomplicated malaria. However there may be need to further investigate the comparatively low efficacy rate found in Nkhotakota district in order to identify possible determinants of treatment failure.

Comparison of anaemia and parasitaemia as indicators of malaria control in household and EPI-health facility surveys in Malawi.

BACKGROUND: The World Health Organization has recommended that anaemia be used as an additional indicator to monitor malaria burden at the community level as malaria interventions are nationally scaled up. To date, there are no published evaluations of this recommendation. METHODS: To evaluate this recommendation, a comparison of anaemia and parasitaemia among 6-30 month old children was made during two repeated cross-sectional household (HH) and health facility (HF) surveys in six districts across Malawi at baseline (2005) and in a follow-up survey (2008) after a scale up of malaria control interventions. RESULTS: HH net ownership did not increase between the years (50.5% vs. 49.8%), but insecticide treated net (ITN) ownership increased modestly from 41.5% (95% CI: 37.2%-45.8%) in 2005 to 45.3% (95% CI: 42.6%-48.0%) in 2008. ITN use by children 6-30 months old, who were living in HH with at least one net, increased from 73.6% (95% CI:68.2%-79.1%) to 80.0% (95% CI:75.9%-84.1%) over the three-year period. This modest increase in ITN use was associated with a decrease in moderate to severe anaemia (Hb <8 g/dl) from 18.4% (95% CI:14.9%-21.8%) in 2005 to 15.4% (13.2%-17.7%) in 2008, while parasitaemia, measured as positive-slide microscopy, decreased from 18.9% (95% CI:14.7%-23.2%) to 16.9% (95% CI:13.8%-20.0%), a relative reduction of 16% and 11%, respectively. In HF surveys, anaemia prevalence decreased from 18.3% (95% CI: 14.9%-21.7%) to 15.4% (95% CI: 12.7%-18.2%), while parasitaemia decreased from 30.6% (95% CI: 25.7%-35.5%) to 13.2% (95% CI: 10.6%-15.8%), a relative reduction of 15% and 57%, respectively. CONCLUSION: Increasing access to effective malaria prevention was associated with a reduced burden of malaria in young Malawian children. Anaemia measured at the HF level at time of routine vaccination may be a good surrogate indicator for its measurement at the HH level in evaluating national malaria control programmes.

Integration of insecticide-treated net distribution into routine immunization services in Malawi: a pilot study.

OBJECTIVES: To determine the feasibility of distributing insecticide-treated nets (ITNs) through routine immunization services, to increase ownership and use of ITNs among high-risk groups, whereas maintaining or improving timely completion of routine vaccinations. METHODS: Free ITNs were provided with timely completion of routine vaccinations in two intervention districts in southern Malawi for 15 months. Cross-sectional baseline and follow-up household surveys were conducted in the two intervention districts and one control district. RESULTS: Insecticide-treated nets utilization among children aged 12-23 months roughly doubled in the two intervention districts and did not change in the control district. Timely vaccination coverage increased in all three districts. The percentage of children aged 12-23 months who were both fully vaccinated by 12 months and slept under an ITN the night prior to the interview increased from 10-14% at baseline to 40-44% at follow-up in the intervention districts (P < 0.001), but did not change significantly in the control district. CONCLUSIONS: This study is the first to evaluate the provision of free ITNs at completion of a child's primary vaccination series, demonstrating that such a linkage is both feasible and can result in improved coverage with the combined services. Additional studies are needed to determine whether such a model is effective in other countries, and whether integration of other health services with immunization delivery could also be synergistic.

Developing national treatment policy for falciparum malaria in Africa: Malawi experience.

The emergence and spread across sub-Saharan Africa of Plasmodium falciparum resistant to the inexpensive antimalarials chloroquine and sulfadoxine-pyrimethamine has worsened the health and hampered the socio-economic development of affected countries, a situation that calls for urgent review of malaria treatment policies in these countries. The Roll Back Malaria (RBM) initiative promotes strong partnerships for implementing effective malaria control measures. The development of clear policies to guide such implementation at country level offers a way of assessing the achievement of set milestones in this collaborative venture. In this article we describe the policy development process for the treatment of falciparum malaria in Africa, based on experience in Malawi, where the first-line drug treatment was recently changed from sulfadoxine-pyrimethamine to an artemisinin combination therapy.