The public health impact and cost-effectiveness of the R21/Matrix-M malaria vaccine: a mathematical modelling study

BACKGROUND

The R21/Matrix-M vaccine has demonstrated high efficacy against Plasmodium falciparum clinical malaria in children in sub-Saharan Africa. Using trial data, we aimed to estimate the public health impact and cost-effectiveness of vaccine introduction across sub-Saharan Africa.

METHODS

We fitted a semi-mechanistic model of the relationship between anti-circumsporozoite protein antibody titres and vaccine efficacy to data from 3 years of follow-up in the phase 2b trial of R21/Matrix-M in Nanoro, Burkina Faso. We validated the model by comparing predicted vaccine efficacy to that observed over 12-18 months in the phase 3 trial. Integrating this framework within a mathematical transmission model, we estimated the cases, malaria deaths, and disability-adjusted life-years (DALYs) averted and cost-effectiveness over a 15-year time horizon across a range of transmission settings in sub-Saharan Africa. Cost-effectiveness was estimated incorporating the cost of vaccine introduction (dose, consumables, and delivery) relative to existing interventions at baseline. We report estimates at a median of 20% parasite prevalence in children aged 2-10 years (PfPR2-10) and ranges from 3% to 65% PfPR2-10.

FINDINGS

Anti-circumsporozoite protein antibody titres were found to satisfy the criteria for a surrogate of protection for vaccine efficacy against clinical malaria. Age-based implementation of a four-dose regimen of R21/Matrix-M vaccine was estimated to avert 181 825 (range 38 815-333 491) clinical cases per 100 000 fully vaccinated children in perennial settings and 202 017 (29 868-405 702) clinical cases per 100 000 fully vaccinated children in seasonal settings. Similar estimates were obtained for seasonal or hybrid implementation. Under an assumed vaccine dose price of US$3, the incremental cost per clinical case averted was $7 (range 4-48) in perennial settings and $6 (3-63) in seasonal settings and the incremental cost per DALY averted was $34 (29-139) in perennial settings and $30 (22-172) in seasonal settings, with lower cost-effectiveness ratios in settings with higher PfPR2-10.

INTERPRETATION

Introduction of the R21/Matrix-M malaria vaccine could have a substantial public health benefit across sub-Saharan Africa.

FUNDING

The Wellcome Trust, the Bill & Melinda Gates Foundation, the UK Medical Research Council, the European and Developing Countries Clinical Trials Partnership 2 and 3, the NIHR Oxford Biomedical Research Centre, and the Serum Institute of India, Open Philanthropy.

Cost-effectiveness of adding indoor residual spraying to case management in Afghan refugee settlements in Northwest Pakistan during a prolonged malaria epidemic

Introduction

Financing of malaria control for displaced populations is limited in scope and duration, making cost-effectiveness analyses relevant but difficult. This study analyses cost-effectiveness of adding prevention through targeted indoor residual spraying (IRS) to case management in Afghan refugee settlements in Pakistan during a prolonged malaria epidemic.

Methods/Findings

An intervention study design was selected, taking a societal perspective. Provider and household costs of vector control and case management were collected from provider records and community survey. Health outcomes (e.g. cases and DALYs averted) were derived and incremental cost-effectiveness ratios (ICERs) for cases prevented and DALYs averted calculated. Population, treatment cost, women’s time, days of productivity lost, case fatality rate, cases prevented, and DALY assumptions were tested in sensitivity analysis. Malaria incidence peaked at 44/1,000 population in year 2, declining to 14/1,000 in year 5. In total, 370,000 malaria cases, 80% vivax, were diagnosed and treated and an estimated 67,988 vivax cases and 18,578 falciparum and mixed cases prevented. Mean annual programme cost per capita was US$0.56. The additional cost of including IRS over five years per case prevented was US$39; US$50 for vivax (US$43 in years 1–3, US$80 in years 4–5) and US$182 for falciparum (US$139 in years 1–3 and US$680 in years 4–5). Per DALY averted this was US$266 (US$220 in years 1–3 and US$486 in years 4–5) and thus ‘highly cost-effective’ or cost-effective using WHO and comparison thresholds.

Conclusions

Adding IRS was cost-effective in this moderate endemicity, low mortality setting. It was more cost-effective when transmission was highest, becoming less so as transmission reduced. Because vivax was three times more common than falciparum and the case fatality rate was low, cost-effectiveness estimations for cases prevented appear reliable and more definitive for vivax malaria.

We conducted a cost-effectiveness analysis of adding malaria prevention to routine malaria diagnosis and treatment in Afghan refugee settlements in Pakistan during a five-year malaria epidemic. We found that malaria incidence peaked at 44 per 1,000 in year 2 and declined to 14 per 1,000 in year 5, with an average annual programme cost per capita of US$0.56 in 2015 currency. Cost per case prevented averaged US$88 (US$111 for vivax, US$442 for falciparum), per death prevented averaged US$316,734, and per DALY averted averaged US$601. The additional cost of including IRS over five years per case prevented was US$39 (US$50 for vivax and US$182 for falciparum malaria case prevented) and per DALY averted was US$266. While our cost-effectiveness results were relatively high, when compared with internationally recognised cost-effectiveness thresholds both prevention and case management were highly cost-effective, indicating the relevance of an integrated approach for epidemic malaria control and global malaria elimination.

Treatment-seeking behaviour and associated costs for malaria in Papua, Indonesia

BACKGROUND

Malaria remains a significant public health issue in Eastern Indonesia, where multidrug resistant Plasmodium falciparum and Plasmodium vivax are highly prevalent. The objective of this study was to describe treatment-seeking behaviour and household costs prior to a change to a unified treatment policy of dihydroartemisinin-piperaquine in Mimika district, Papua province in 2006.

METHODS

In 2005 a randomized cross-sectional household survey was conducted to collect data on demographics, socio-economic status (SES), treatment-seeking, case management, and household costs. Information on the cost of illness was also collected from patients exiting health facilities, in order to compare the cost of episodes diagnosed as P. vivax compared with those diagnosed as P. falciparum.

RESULTS

825 households were included in the survey. Of the 764 individuals who sought treatment for fever outside the home in the last month, 46% (349/764) went to a public health facility. Of the 894 reported visits to healthcare providers, 48% (433) resulted in a blood test, of which 78% (337) were reportedly positive. Only 10% (17/177) of individuals who reported testing positive for P. falciparum or mixed infection received the first-line treatment of chloroquine with SP, and 38% (61/159) of those with a diagnosis of P. vivax reportedly received the first-line treatment of chloroquine and primaquine. Overall, public facilities were more likely to prescribe the correct prevailing first-line drug combinations than private providers (OR = 3.77 [95% CI 2.31-6.14], p < 0.001). The mean cost to the household of an episode of P. vivax was similar to the cost of P. falciparum [US$44.50 (SD: 46.23) vs US$48.58 (SD: 64.65)].

CONCLUSIONS

Private providers were a popular source of treatment for malaria, but adherence to the national guidelines was low and the economic burden of malaria for both P. falciparum and P. vivax infections was substantial. Engagement with the private sector is needed to ensure that patients have access to affordable good quality, effective diagnostics and anti-malarials for both P. falciparum and P. vivax.

The RooPfs study to assess whether improved housing provides additional protection against clinical malaria over current best practice in The Gambia: study protocol for a randomized controlled study and ancillary studies

BACKGROUND

In malaria-endemic areas, residents of modern houses have less malaria than those living in traditional houses. This study will determine if modern housing provides incremental protection against clinical malaria over the current best practice of long-lasting insecticidal nets (LLINs) and prompt treatment in The Gambia, determine the incremental cost-effectiveness of the interventions, and analyze the housing market in The Gambia.

METHODS/DESIGN

A two-armed, household, cluster-randomized, controlled study will be conducted to assess whether improved housing and LLINs combine to provide better protection against clinical malaria in children than LLINs alone in The Gambia. The unit of randomization will be the household, defined as a house and its occupants. A total of 800 households will be enrolled and will receive LLINs, and 400 will receive improved housing before clinical follow-up. One child aged 6 months to 13 years will be enrolled from each household and followed for clinical malaria using active case detection to estimate malaria incidence for two malaria transmission seasons. Episodes of clinical malaria will be the primary endpoint. Study children will be surveyed at the end of each transmission season to estimate the prevalence of Plasmodium falciparum infection, parasite density, and the prevalence of anemia. Exposure to malaria parasites will be assessed using light traps, followed by detection of Anopheles gambiae species and sporozoite infection. Ancillary economic and social science studies will undertake a cost-effectiveness analysis and use qualitative and participatory methods to explore the acceptability of the housing modifications and to design strategies for scaling-up housing interventions.

DISCUSSION

The study is the first of its kind to measure the efficacy of housing on reducing clinical malaria, assess the incremental cost-effectiveness of improved housing, and identify mechanisms for scaling up housing interventions. Trial findings will help inform policy makers on improved housing for malaria control in sub-Saharan Africa.

TRIAL REGISTRATION

ISRCTN Registry, ISRCTN02622179 . Registered on 23 September 2014.

The Future of the RTS,S/AS01 Malaria Vaccine: An Alternative Development Plan

Roly Gosling and Lorenz von Seidlein consider a potential future development plan for the RTS,S/AS01 malaria vaccine.

Public health impact and cost-effectiveness of the RTS,S/AS01 malaria vaccine: a systematic comparison of predictions from four mathematical models

BACKGROUND

The phase 3 trial of the RTS,S/AS01 malaria vaccine candidate showed modest efficacy of the vaccine against Plasmodium falciparum malaria, but was not powered to assess mortality endpoints. Impact projections and cost-effectiveness estimates for longer timeframes than the trial follow-up and across a range of settings are needed to inform policy recommendations. We aimed to assess the public health impact and cost-effectiveness of routine use of the RTS,S/AS01 vaccine in African settings.

METHODS

We compared four malaria transmission models and their predictions to assess vaccine cost-effectiveness and impact. We used trial data for follow-up of 32 months or longer to parameterise vaccine protection in the group aged 5-17 months. Estimates of cases, deaths, and disability-adjusted life-years (DALYs) averted were calculated over a 15 year time horizon for a range of levels of Plasmodium falciparum parasite prevalence in 2-10 year olds (PfPR2-10; range 3-65%). We considered two vaccine schedules: three doses at ages 6, 7·5, and 9 months (three-dose schedule, 90% coverage) and including a fourth dose at age 27 months (four-dose schedule, 72% coverage). We estimated cost-effectiveness in the presence of existing malaria interventions for vaccine prices of US$2-10 per dose.

FINDINGS

In regions with a PfPR2-10 of 10-65%, RTS,S/AS01 is predicted to avert a median of 93,940 (range 20,490-126,540) clinical cases and 394 (127-708) deaths for the three-dose schedule, or 116,480 (31,450-160,410) clinical cases and 484 (189-859) deaths for the four-dose schedule, per 100,000 fully vaccinated children. A positive impact is also predicted at a PfPR2-10 of 5-10%, but there is little impact at a prevalence of lower than 3%. At $5 per dose and a PfPR2-10 of 10-65%, we estimated a median incremental cost-effectiveness ratio compared with current interventions of $30 (range 18-211) per clinical case averted and $80 (44-279) per DALY averted for the three-dose schedule, and of $25 (16-222) and $87 (48-244), respectively, for the four-dose schedule. Higher ICERs were estimated at low PfPR2-10 levels.

INTERPRETATION

We predict a significant public health impact and high cost-effectiveness of the RTS,S/AS01 vaccine across a wide range of settings. Decisions about implementation will need to consider levels of malaria burden, the cost-effectiveness and coverage of other malaria interventions, health priorities, financing, and the capacity of the health system to deliver the vaccine.

FUNDING

PATH Malaria Vaccine Initiative; Bill & Melinda Gates Foundation; Global Good Fund; Medical Research Council; UK Department for International Development; GAVI, the Vaccine Alliance; WHO.

A Cost-Effectiveness Analysis of Plasmodium falciparum Malaria Elimination in Hainan Province, 2002-2012

In Hainan Province, China, great achievements in elimination of falciparum malaria have been made since 2010. There have been no locally acquired falciparum malaria cases since that time. The cost-effectiveness of elimination of falciparum malaria has been analyzed in Hainan Province. There were 4,422 falciparum malaria cases reported from 2002 to 2012, more cases occurred in males than in females. From 2002 to 2012, a total of 98.5 disability-adjusted life years (DALYs) were reported because of falciparum malaria. Populations in the age ranges of 15-25 and 30-44 years had higher incidences and DALYs than other age groups. From 2002 to 2012, malaria-related costs for salaries of staff, funds from the provincial government, national government, and the GFATM were US$3.02, US$2.24, US$1.44, and US$5.08 million, respectively. An estimated 9,504 falciparum malaria cases were averted during the period 2003-2012. The estimated cost per falciparum malaria case averted was US$116.5. The falciparum malaria elimination program in Hainan was highly effective and successful. However, funding for maintenance is still needed because of imported cases.

Economic evaluation of a cluster randomized trial of interventions to improve health workers' practice in diagnosing and treating uncomplicated malaria in Cameroon

BACKGROUND

Malaria rapid diagnostic tests (RDTs) are a valid alternative to malaria testing with microscopy and are recommended for the testing of febrile patients before prescribing an antimalarial. There is a need for interventions to support the uptake of RDTs by health workers.

OBJECTIVE

To evaluate the cost-effectiveness of introducing RDTs with basic or enhanced training in health facilities in which microscopy was available, compared with current practice.

METHODS

A three-arm cluster randomized trial was conducted in 46 facilities in central and northwest Cameroon. Basic training had a practical session on RDTs and lectures on malaria treatment guidelines. Enhanced training included small-group activities designed to change health workers' practice and reduce the consumption of antimalarials among test-negative patients. The primary outcome was the proportion of febrile patients correctly treated: febrile patients should be tested for malaria, artemisinin combination therapy should be prescribed for confirmed cases, and no antimalarial should be prescribed for patients who are test-negative. Individual patient data were obtained from facility records and an exit survey. Costs were estimated from a societal perspective using project reports and patient exit data. The analysis used bivariate multilevel modeling and adjusted for imbalance in baseline covariates.

RESULTS

Incremental cost per febrile patient correctly treated was $8.40 for the basic arm and $3.71 for the enhanced arm. On scale-up, it was estimated that RDTs with enhanced training would save $0.75 per additional febrile patient correctly treated.

CONCLUSIONS

Introducing RDTs with enhanced training was more cost-effective than RDTs with basic training when each was compared with current practice.

Ethics, economics, and the use of primaquine to reduce falciparum malaria transmission in asymptomatic populations

Yoel Lubell and colleagues consider ethical and economic perspectives on mass drug administration of primaquine to limit transmission of P. falciparum malaria. Please see later in the article for the Editors' Summary.

Measuring changes in Plasmodium falciparum transmission: precision, accuracy and costs of metrics

As malaria declines in parts of Africa and elsewhere, and as more countries move towards elimination, it is necessary to robustly evaluate the effect of interventions and control programmes on malaria transmission. To help guide the appropriate design of trials to evaluate transmission-reducing interventions, we review 11 metrics of malaria transmission, discussing their accuracy, precision, collection methods and costs and presenting an overall critique. We also review the nonlinear scaling relationships between five metrics of malaria transmission: the entomological inoculation rate, force of infection, sporozoite rate, parasite rate and the basic reproductive number, R0. Our chapter highlights that while the entomological inoculation rate is widely considered the gold standard metric of malaria transmission and may be necessary for measuring changes in transmission in highly endemic areas, it has limited precision and accuracy and more standardised methods for its collection are required. In areas of low transmission, parasite rate, seroconversion rates and molecular metrics including MOI and mFOI may be most appropriate. When assessing a specific intervention, the most relevant effects will be detected by examining the metrics most directly affected by that intervention. Future work should aim to better quantify the precision and accuracy of malaria metrics and to improve methods for their collection.

The economic burden of malaria on households and the health system in Enugu State southeast Nigeria

Background

Malaria is the number one public health problem in Nigeria, responsible for about 30% of deaths in under-fives and 25% of deaths in infants and 11% maternal mortality. This study estimated the economic burden of malaria in Nigeria using the cost of illness approach.

Methods

A cross-sectional study was undertaken in two malaria holo-endemic communities in Nigeria, involving both community and hospital based surveys. A random sample of 500 households was interviewed using interviewer administered questionnaire. In addition, 125 exit interviews for inpatient department stays (IPD) and outpatient department visits (OPD) were conducted and these were complemented with data abstraction from 125 patient records.

Results

From the household survey, over half of the households (57.6%) had an episode of malaria within one month to the date of the interview. The average household expenditure per case was 12.57US$ and 23.20US$ for OPD and IPD respectively. Indirect consumer costs of treatment were higher than direct consumer medical costs. From a health system perspective, the recurrent provider costs per case was 30.42 US$ and 48.02 US$ for OPD and IPD while non recurrent provider costs were 133.07US$ and 1857.15US$ for OPD and IPD. The mode of payment was mainly through out-of-pocket spending (OOPS).

Conclusion

Private expenditure on treatment of malaria constitutes a high economic burden to households and to the health system. Removal of user fees and interventions that will decrease the use of OOPS for treatment of malaria will significantly decrease the economic burden of malaria to both households and the health system.

Socioeconomic development as an intervention against malaria: a systematic review and meta-analysis

BACKGROUND

Future progress in tackling malaria mortality will probably be hampered by the development of resistance to drugs and insecticides and by the contraction of aid budgets. Historically, control was often achieved without malaria-specific interventions. Our aim was to assess whether socioeconomic development can contribute to malaria control.

METHODS

We did a systematic review and meta-analysis to assess whether the risk of malaria in children aged 0-15 years is associated with socioeconomic status. We searched Medline, Web of Science, Embase, the Cochrane Database of Systematic Reviews, the Campbell Library, the Centre for Reviews and Dissemination, Health Systems Evidence, and the Evidence for Policy and Practice Information and Co-ordinating Centre evidence library for studies published in English between Jan 1, 1980, and July 12, 2011, that measured socioeconomic status and parasitologically confirmed malaria or clinical malaria in children. Unadjusted and adjusted effect estimates were combined in fixed-effects and random-effects meta-analyses, with a subgroup analysis for different measures of socioeconomic status. We used funnel plots and Egger's linear regression to test for publication bias.

FINDINGS

Of 4696 studies reviewed, 20 met the criteria for inclusion in the qualitative analysis, and 15 of these reported the necessary data for inclusion in the meta-analysis. The odds of malaria infection were higher in the poorest children than in the least poor children (unadjusted odds ratio [OR] 1·66, 95% CI 1·35-2·05, p<0·001, I(2)=68%; adjusted OR 2·06, 1·42-2·97, p<0·001, I(2)=63%), an effect that was consistent across subgroups.

INTERPRETATION

Although we would not recommend discontinuation of existing malaria control efforts, we believe that increased investment in interventions to support socioeconomic development is warranted, since such interventions could prove highly effective and sustainable against malaria in the long term.

FUNDING

UK Department for International Development.

Malaria risk factors in North West Tanzania: the effect of spraying, nets and wealth

Malaria prevalence remains high in many African countries despite massive scaling-up of insecticide treated nets (ITN) and indoor residual spraying (IRS). This paper evaluates the protective effect of pyrethroid IRS and ITNs in relation to risk factors for malaria based on a study conducted in North-West Tanzania, where IRS has been conducted since 2007 and universal coverage of ITNs has been carried out recently. In 2011 community-based cross-sectional surveys were conducted in the two main malaria transmission periods that occur after the short and long rainy seasons. These included 5,152 and 4,325 children aged 0.5–14 years, respectively. Data on IRS and ITN coverage, household demographics and socio-economic status were collected using an adapted version of the Malaria Indicator Survey. Children were screened for malaria by rapid diagnostic test. In the second survey, haemoglobin density was measured and filter paper blood spots were collected to determine age-specific sero-prevalence in each community surveyed. Plasmodium falciparum infection prevalence in children 0.5–14 years old was 9.3% (95%CI:5.9–14.5) and 22.8% (95%CI:17.3–29.4) in the two surveys. Risk factors for infection after the short rains included households not being sprayed (OR = 0.39; 95%CI:0.20–0.75); low community net ownership (OR = 0.45; 95%CI:0.21–0.95); and low community SES (least poor vs. poorest tertile: OR = 0.13, 95%CI:0.05–0.34). Risk factors after the long rains included household poverty (per quintile increase: OR = 0.89; 95%CI:0.82–0.97) and community poverty (least poor vs. poorest tertile: OR = 0.26, 95%CI:0.15–0.44); household IRS or high community ITN ownership were not protective. Despite high IRS coverage and equitable LLIN distribution, poverty was an important risk factor for malaria suggesting it could be beneficial to target additional malaria control activities to poor households and communities. High malaria prevalence in some clusters and the limited protection given by pyrethroid IRS and LLINs suggest that it may be necessary to enhance established vector control activities and consider additional interventions.

Cost-effectiveness of the introduction of a pre-erythrocytic malaria vaccine into the expanded program on immunization in sub-Saharan Africa: analysis of uncertainties using a stochastic individual-based simulation model of Plasmodium falciparum malaria

OBJECTIVE

To evaluate the cost-effectiveness of introducing the RTS,S malaria vaccine into the Expanded Programme on Immunization (EPI) in Sub-Saharan Africa (SSA), the contributions of different sources of uncertainty, and the associated expected value of perfect information (EVPI).

METHODS

Vaccination was simulated in populations of 100,000 people at 10 different entomological inoculation rates (EIRs), using an existing stochastic model and a 10-year time horizon. Incremental cost-effectiveness ratios (ICERs) and EVPI were computed from weighted averages of outputs using two different assignments of the EIR distribution in 2007. Uncertainty was evaluated by resampling of epidemiological, vaccination, and health systems model parameters.

RESULTS

Health benefits were predicted consistently only at low transmission, and program costs always substantially exceeded case management savings. Optimal cost-effectiveness was at EIR of about 10 infectious bites per annum (ibpa). Main contributors to ICER uncertainty were uncertainty in transmission intensity, price per vaccine dose, decay rate of the vaccine effect, degree of homogeneity in host response, and some epidemiological model parameters. Other health system costs were unimportant. With a ceiling ratio of 207 international dollars per disability-adjusted life-year averted, 52.4% of parameterizations predicted cost-effectiveness in the primary analysis.

CONCLUSIONS

Cost-effectiveness of RTS,S will be maximal in low endemicity settings (EIR 2-20 ibpa). Widespread deployment of other transmission-reducing interventions will thus improve cost-effectiveness, suggesting a selective introduction strategy. EVPI is substantial. Accrual of up-to-date information on local endemicity to guide deployment decisions would be highly efficient.

Equity and adequacy of international donor assistance for global malaria control: an analysis of populations at risk and external funding commitments

BACKGROUND

Financing for malaria control has increased as part of international commitments to achieve the Millennium Development Goals (MDGs). We aimed to identify the unmet financial needs that would be biologically and economically equitable and would increase the chances of reaching worldwide malaria-control ambitions.

METHODS

Populations at risk of stable Plasmodium falciparum or Plasmodium vivax transmission were calculated for 2007 and 2009 for 93 malaria-endemic countries to measure biological need. National per-person gross domestic product (GDP) was used to define economic need. An analysis of external donor assistance for malaria control was done for the period 2002-09 to compute overall and annualised per-person at-risk-funding commitments. Annualised malaria donor assistance was compared with independent predictions of funding needed to reach international targets of 80% coverage of best practices in case-management and effective disease prevention. Countries were ranked in relation to biological, economic, and unmet needs to examine equity and adequacy of support by 2010.

FINDINGS

International financing for malaria control has increased by 166% (from $0·73 billion to $1·94 billion) since 2007 and is broadly consistent with biological needs. African countries have become major recipients of external assistance; however, countries where P vivax continues to pose threats to control ambitions are not as well funded. 21 countries have reached adequate assistance to provide a comprehensive suite of interventions by 2009, including 12 countries in Africa. However, this assistance was inadequate for 50 countries representing 61% of the worldwide population at risk of malaria-including ten countries in Africa and five in Asia that coincidentally are some of the poorest countries. Approval of donor funding for malaria control does not correlate with GDP.

INTERPRETATION

Funding for malaria control worldwide is 60% lower than the US$4·9 billion needed for comprehensive control in 2010; this includes funding shortfalls for a wide range of countries with different numbers of people at risk and different levels of domestic income. More efficient targeting of financial resources against biological need and national income should create a more equitable investment portfolio that with increased commitments will guarantee sustained financing of control in countries most at risk and least able to support themselves.

FUNDING

Wellcome Trust.

Focusing on quality patient care in the new global subsidy for malaria medicines

Tido von Schoen-Angerer and colleagues discuss the new Affordable Medicines Facility for malaria (AMFm), which subsidizes and facilitates access to artemisinin-based combination therapy, and what mechanisms are needed to ensure it stays focused on quality patient care.

A major transition in malaria treatment: the adoption and deployment of artemisinin-based combination therapies

Parasite resistance to conventional antimalarial medicines has led, in recent years, to a dramatic shift in malaria treatment. Sixty-seven countries with endemic Plasmodium falciparum malaria, 41 of them in Africa, have recently adopted the highly effective artemisinin-based combination therapies (ACTs). In 2005, 31.3 million ACT treatment courses were procured globally for public sector use, 25.5 million of them in Africa. However, in the 39 countries, and in particular the 21 African countries in which ACTs are being deployed, access to these medicines is still unacceptably low. After a period of market instability, the global manufacturing capacity for ACTs is now sufficient to meet the demand. However, increased and sustained financing will be necessary to extend the current levels of ACT coverage. Artemisinins as monotherapies are widely available in the private sector of 47 endemic countries, and their consumption will, if unabated, promote resistance to artemisinins and compromise the effectiveness of ACTs.

Responding to the challenge of antimalarial drug resistance by routine monitoring to update national malaria treatment policies

Reduced sensitivity of Plasmodium falciparum to formerly recommended cheap and well-known antimalarial drugs places an increasing burden on malaria control programs and national health systems in endemic countries. The high costs of the new artemisinin-based combination treatments underline the use of rational and updated malaria treatment policies, but defining and updating such policies requires a sufficient volume of high-quality drug-resistance data collected at national and regional levels. Three main tools are used for drug resistance monitoring, including therapeutic efficacy tests, in vitro tests, and analyses of molecular markers. Data obtained with the therapeutic efficacy test conducted according to the standard protocol of the World Health Organization are most useful for updating national treatment policies, while the in vitro test and molecular markers can provide important additional information about changing patterns of resistance. However, some of the tests are technically demanding, and thus there is a need for more resources for training and capacity building in endemic countries to be able to adequately respond to the challenge of drug resistance.

Increasing burden of childhood severe malaria in a Nigerian tertiary hospital: implication for control

Malaria remains an important public heath concern in Nigeria because of its impact on child and maternal health, but the contribution of severe malaria to morbidity among Nigerian children was scantly reported. This study was undertaking to document the hospital-burden of severe malaria among children in Ibadan in order to reflect on the impacts and health implications of the current malaria control strategies. A review of 6-year case records of all children admitted to the emergency ward of the University College Hospital Ibadan was carried out. Cases of severe malaria were defined as those children in whom parasitaemia were confirmed with blood film microscopy and any of the WHO case definitions for severe malaria was documented. Severe malaria cases constituted 11.3% of 16 031 admissions (2000-05) with 89.1% being children <5 years old. Cerebral malaria accounted for about one-fifth (19.7%) of all severe malaria cases. The yearly proportional morbidity rate from severe malaria ranged from 8.7% to 13.2% with significant increase from 2000 to 2004 (X2 = 48.49; df = 5; P < 0.001). Severe malaria accounted for 12.4% of all paediatric deaths with an estimated overall case fatality rate of 9.6%. Deaths from malaria were significantly associated with wasting (Z-score for weight-for-height <or=2.0), age <2 years, hypoglycaemia and respiratory distress. Our data demonstrated an increased trend in morbidity from severe malaria over the study period. Severe malarial anaemia was a more common complication of Plasmodium falciparum malaria than cerebral malaria in hospitalized Nigerian children and it was associated with a high number of deaths. The consequences of high rate of severe malaria may be beyond health as it also affects the economy and the developmental prospects of the country. There may therefore a need to review the current strategies for malaria control in Nigeria.

The economics of malaria in pregnancy--a review of the evidence and research priorities

Malaria in pregnancy is a major public-health problem in the developing world. However, on review of the evidence, we found its economic impact is not well documented. Adequately capturing the economic burden of malaria in pregnancy requires good epidemiological data including effects to the mother and baby, and better understanding of the long-term health and economic costs of malaria in pregnancy. We reviewed evidence on coverage, equity, cost, and cost-effectiveness of interventions to tackle malaria in pregnancy and found that although key interventions are highly cost effective, coverage is currently inadequate and fails to reach the poor. The evidence on interventions to improve treatment of malaria in pregnancy is scarce, and fails to adequately capture the benefits. There is also lack of data on cost-effectiveness of other interventions, especially outside of Africa, in low transmission settings, and for non-falciparum malaria. Research priorities on the economics of malaria in pregnancy are identified.

Artemether/lumefantrine in the treatment of uncomplicated falciparum malaria

At present, artemether/lumefantrine (AL) is the only fixed-dose artemisinin-based combination therapy recommended and pre-qualified by WHO for the treatment of uncomplicated malaria caused by Plasmodium falciparum. It has been shown to be effective both in sub-Saharan Africa and in areas with multi-drug resistant P. falciparum in southeast Asia. It is currently recommended as first-line treatment for uncomplicated malaria in several countries. However, AL has a complex treatment regimen and the issues of adherence to treatment with AL by adult patients and real-life effectiveness in resource-poor settings will be critical in determining its useful therapeutic life, especially in Africa, where the major burden of malaria is felt. There are also issues of safety of the artemisinin derivatives, including AL, which will need to be monitored as their use in resource-poor settings becomes more widespread. There are limited pharmacokinetic studies of AL in African patients, and the relationship between plasma drug concentration and efficacy in these patients is unknown. Moreover, the effects of factors such as concurrently administered drugs, malnutrition and co-infections with HIV and helminths in malaria patients are not well understood. These will need to be addressed, although a few studies on possible drug-drug interactions with commonly used drugs, such as quinine, mefloquine and ketoconazole, have been reported. This review focuses on the status of clinical pharmacology, efficacy and real-life effectiveness of AL under a variety of settings, and highlights some of the challenges that face policy makers during the deployment of AL, especially in Africa, with regards to ensuring that those who most need this therapy will not be denied access due to official inefficiency in procurement and distribution processes.

An approach to model the costs and effects of case management of Plasmodium falciparum malaria in sub-saharan Africa

An important shortcoming of existing methods for estimating the cost-effectiveness of malaria control interventions is that the incidence of illness and transmission dynamics are assumed to be independent of the case management system. We have developed a model for case management and integrated it into a stochastic simulation of Plasmodium falciparum malaria dynamics. This allows us to predict the incidence of clinical episodes and of mortality while incorporating effects of case management on persistence of parasites and transmission. We make predictions for a range of different transmission intensities in sub-Saharan Africa and simulate a range of case management scenarios with different coverage rates. The model predicts that high treatment rates have a proportionately greater epidemiologic impact at low transmission levels. Further development is needed for models for health-seeking behavior and referral patterns. The current model is a first step towards useful predictions of the epidemiologic and economic consequences of introducing and/or scaling-up of malaria control interventions.

PREDICTING THE COST-EFFECTIVENESS OF INTRODUCING A PRE-ERYTHROCYTIC MALARIA VACCINE INTO THE EXPANDED PROGRAM ON IMMUNIZATION IN TANZANIA

We model the cost-effectiveness of the introduction of a pre-erythrocytic malaria vaccine into the Expanded Program on Immunization. We use a dynamic stochastic simulation model of the epidemiology of Plasmodium falciparum in malaria-endemic areas and of case management in Tanzania. We consider a range of vaccine characteristics and a range of transmission settings. At low vaccine prices, the cost-effectiveness of such vaccines may be similar to that of other established preventative and curative interventions against malaria. The cost-effectiveness ratio increases rapidly and approximately linearly with vaccine cost per dose. The approach can be adopted for comparative analyses of the cost effectiveness of different vaccines and other intervention strategies.

The costs of changing national policy: lessons from malaria treatment policy guidelines in Tanzania

OBJECTIVE

To document the cost incurred by the Tanzanian government by changing the policy on first-line treatment of malaria, from chloroquine to sulfadoxine-pyrimethamine.

METHODS

Costs were analysed from the perspective of the Ministry of Health and included all sources of funding. Costs external to the public health sector (e.g. private and community costs) were not included. The base case analysis adopted an incremental rather than a full cost approach, assuming that an organizational infrastructure was already in place. However, specific attention was paid to the burden placed on National Malaria Control Program staff. We also costed activities planned but not implemented to estimate the total expense for an 'ideal' process.

RESULTS

Total costs were Tsh 795 million (USD 813,743), with the largest proportion accounted for by training. Costs of the policy change process were equivalent to about 4% of annual government and donor expenditure on malaria and to about 1% of overall public expenditure on health. A number of planned activities were not implemented; including these would bring the total cost to Ts 880 million (USD 896,130).

CONCLUSION

On top of extra costs for the drugs themselves, a change in treatment policy requires time, resources and substantial management capacity at national and local level. A better understanding of these issues and the costs involved benefits countries planning and implementing policy change.

Production of the antimalarial drug precursor artemisinic acid in engineered yeast

Malaria is a global health problem that threatens 300-500 million people and kills more than one million people annually. Disease control is hampered by the occurrence of multi-drug-resistant strains of the malaria parasite Plasmodium falciparum. Synthetic antimalarial drugs and malarial vaccines are currently being developed, but their efficacy against malaria awaits rigorous clinical testing. Artemisinin, a sesquiterpene lactone endoperoxide extracted from Artemisia annua L (family Asteraceae; commonly known as sweet wormwood), is highly effective against multi-drug-resistant Plasmodium spp., but is in short supply and unaffordable to most malaria sufferers. Although total synthesis of artemisinin is difficult and costly, the semi-synthesis of artemisinin or any derivative from microbially sourced artemisinic acid, its immediate precursor, could be a cost-effective, environmentally friendly, high-quality and reliable source of artemisinin. Here we report the engineering of Saccharomyces cerevisiae to produce high titres (up to 100 mg l(-1)) of artemisinic acid using an engineered mevalonate pathway, amorphadiene synthase, and a novel cytochrome P450 monooxygenase (CYP71AV1) from A. annua that performs a three-step oxidation of amorpha-4,11-diene to artemisinic acid. The synthesized artemisinic acid is transported out and retained on the outside of the engineered yeast, meaning that a simple and inexpensive purification process can be used to obtain the desired product. Although the engineered yeast is already capable of producing artemisinic acid at a significantly higher specific productivity than A. annua, yield optimization and industrial scale-up will be required to raise artemisinic acid production to a level high enough to reduce artemisinin combination therapies to significantly below their current prices.

Fever treatment and household wealth: the challenge posed for rolling out combination therapy for malaria

OBJECTIVE

To investigate the variation in malaria parasitaemia, reported fever, care seeking, antimalarials obtained and household expenditure by socio-economic status (SES), and to assess the implications for ensuring equitable and appropriate use of antimalarial combination therapy.

METHODS

A total of 2,500 households were surveyed in three rural districts in southern Tanzania in mid-2001. Blood samples and data on SES were collected from all households. Half the households completed a detailed questionnaire on care seeking and treatment costs. Households were categorised into SES thirds based on an index of household wealth derived using principal components analysis.

RESULTS

Of individuals completing the detailed survey, 16% reported a fever episode in the previous 2 weeks. People from the better-off stratum were significantly less likely to be parasitaemic, and significantly more likely to obtain antimalarials than those in the middle or poor stratum. The better treatment obtained by the better off led them to spend two to three times more than the middle and poor third spent. This reflected greater use of non-governmental organisation (NGO) facilities, which were the most expensive source of care, and higher expenditure at NGO facilities and drug stores.

CONCLUSION

The coverage of appropriate malaria treatment was low in all SES groups, but the two poorer groups were particularly disadvantaged. As countries switch to antimalarial combination therapy, distribution must be targeted to ensure that the poorest groups fully benefit from these new and highly effective medicines.

Reaching the Abuja target for intermittent preventive treatment of malaria in pregnancy in African women: a review of progress and operational challenges

OBJECTIVE

To review progress with the implementation of intermittent preventive treatment (IPT) for the control of malaria in pregnancy in sub-Saharan Africa (SSA), in order to identify facilitating factors and operational challenges for scaling up IPT delivery.

METHODS

Information on the status of IPT policy, programme and coverage indicators was extracted from published sources. Information on country experiences from both published and unpublished literature was supplemented with semi-structured interviews with malaria programme managers.

RESULTS

Whilst countries in SSA have made important progress with IPT implementation, coverage levels remain low. High antenatal clinic (ANC) attendance alone is not sufficient to ensure high IPT coverage. Staff shortages, poor drug supply, poor ANC access and poor health worker practices are some of the operational challenges in delivering IPT.

CONCLUSION

Country experiences show that IPT can be introduced and scaled up relatively quickly and effectively where there is political will, effective integration between malaria and reproductive health programmes, adequate funding and drug supply, high ANC attendance and community receptiveness. There is however urgent need to better document best practices and lessons as a basis for developing simplified guidelines for dissemination to countries embarking on IPT implementation.

Cost effectiveness analysis of strategies to combat malaria in developing countries

OBJECTIVE

To determine the cost effectiveness of selected malaria control interventions in the context of reaching the millennium development goals for malaria.

DESIGN

Generalised cost effectiveness analysis.

DATA SOURCES

Efficacy data came from the literature and authors' calculations supported by expert opinion. Quantities for resource inputs came from the literature and from expert opinion; prices came from the WHO-CHOICE database.

METHODS

Costs were assessed in year 2000 international dollars, and effects were assessed as disability adjusted life years averted by a 10 year implementation programme. Analysis was restricted to sub-Saharan regions where the most deadly form of malaria, Plasmodium falciparum, is most prevalent. The impact on population health for various interventions, and their combinations, was evaluated at selected coverage levels by using a state-transition model. Sensitivity analysis was done for age weights and discounting.

RESULTS

High coverage with artemisinin based combination treatments was found to be the most cost effective strategy for control of malaria in most countries in sub-Saharan Africa.

CONCLUSIONS

A much larger infusion of resources than those currently available is needed to make headway in the fight to roll back malaria. On cost effectiveness grounds, in most areas in sub-Saharan Africa greater coverage with highly effective combination treatments should be the cornerstone of malaria control. However, treatment alone can achieve less than half the total benefit obtainable through a combination of interventions-scaling up the use of impregnated mosquito nets or indoor spraying with insecticides is also critical. Intermittent presumptive treatment of pregnant women can bring a small but important additional health gain at relatively low cost.

Economic evaluation of a policy change from single-agent treatment for suspected malaria to artesunate-amodiaquine for microscopically confirmed uncomplicated falciparum malaria in the Oussouye District of south-western Senegal

Senegal is changing policy for case management of uncomplicated falciparum malaria, which hitherto is diagnosed clinically and treated with chloroquine or intramuscular quinine. The WHO recommends artemisinin-based combinations for treating falciparum malaria, preferably based on a parasitological diagnosis. There are no economic projections if such a policy were introduced in Senegal. We have conducted a preliminary economic assessment of such a policy change. The study took place in the chloroquine-resistant district of Oussouye in south-western Senegal. We reviewed clinic registers of the district health posts (n=5) from 1996 to 2001, and piloted artesunate combined with amodiaquine (at 4 and 10 mg/kg/day x 3 days respectively) (AS--AQ) for treating slide-proven falciparum malaria during two rainy seasons (2000 and 2001) at one health centre. These data were used to calculate current direct patient costs (clinic visit, diagnosis, drugs) of malaria treatment and project future costs for the district. The robustness of the model was tested by allowing for different drug failure rates and costs of diagnosis. During 1996--2001, the mean number of primary treatments per year was 7654 for a mean, direct cost of 17,452 US dollars to the community. Clinical diagnosis resulted in over-treatment: 56% and 66% in the wet and dry seasons respectively. Current policy leads to substantial drug wastage and excess direct costs for the community. The direct costs of implementing AS-AQ for slide-proven malaria would be 8,150 US dollars (53% less expensive). Studies examining the public health effect and economics of deploying AS--AQ on a wider scale are underway in Senegal.

The global distribution of clinical episodes of Plasmodium falciparum malaria

Interest in mapping the global distribution of malaria is motivated by a need to define populations at risk for appropriate resource allocation and to provide a robust framework for evaluating its global economic impact. Comparison of older and more recent malaria maps shows how the disease has been geographically restricted, but it remains entrenched in poor areas of the world with climates suitable for transmission. Here we provide an empirical approach to estimating the number of clinical events caused by Plasmodium falciparum worldwide, by using a combination of epidemiological, geographical and demographic data. We estimate that there were 515 (range 300-660) million episodes of clinical P. falciparum malaria in 2002. These global estimates are up to 50% higher than those reported by the World Health Organization (WHO) and 200% higher for areas outside Africa, reflecting the WHO's reliance upon passive national reporting for these countries. Without an informed understanding of the cartography of malaria risk, the global extent of clinical disease caused by P. falciparum will continue to be underestimated.

The clinical spectrum of severe malaria in children in the east provincial hospital of Bertoua, Cameroon

Severe malaria claims 1.5 to 2.7 million lives annually most of which are young children in rural areas in sub-Saharan Africa. We retrospectively reviewed the files of 387 patients, admitted and treated for severe malaria according to WHO guidelines, in the Bertoua provincial hospital, a peripheral health center in East Cameroon from 1st October 1998 to 30h October 2000. Our main objective was to study the epidemiological aspects, clinical presentation and outcome. The mean age was 2.7 years (range 2 months - 15 years) among them 214 males and 173 females giving a sex ratio of 1.2. Transmission was observed all year round at variable frequencies with peaks in the rainy seasons. Major symptoms were fever in 202 patients (52.2%), convulsions in 150 (38.8%), prostration in 79 (20.4%) and persistent vomiting in 78 patients (20.2%). Major clinical findings were severe pallor in 196 patients (50.6%) and splenomegaly in 75 patients (19.4%). The average time between onset of symptoms and consultation was 4.4 days (range 1 - 21 days). Blood smears were positive for Plasmodium falciparum in 288 patients (74.4%) and negative in 99 (25.6%). Concerning outcome, recovery was observed in 317 patients (81.9%), interruption of treatment (because of financial constraints) in 58 (15%) and 12 deaths (3.8%). Among the 317 patients who recovered, neurological sequelae were observed in six patients, blindness in four patients and deafness in three patients were the most frequent. We conclude that severe malaria constitutes a major challenge of early diagnosis together with implementation of appropriate treatment especially in rural areas. The use of WHO guidelines in the management of this disease and the recommended preventive measures of vector control have yielded good results in patients managed and followed up in our hospital.

The process of changing national malaria treatment policy: lessons from country-level studies

Widespread resistance of Plasmodium falciparum parasites to commonly used antimalarials, such as chloroquine, has resulted in many endemic countries considering changing their malaria treatment policy. Identifying and understanding the key influences that affect decision-making, and factors that facilitate or undermine policy implementation, is critical for improving the policy process and guiding resource allocation during this process. A historical review of archival documents from Malaŵi and data obtained from in-depth policy studies in four countries (Tanzania, South Africa, Kenya and Peru) that have changed malaria treatment policy provides important lessons about decision-making, the policy cycle and complex policy environment, while specifically identifying strategies successfully employed to facilitate policy-making and implementation. Findings from these country-level studies indicate that the process of malaria drug policy review should be institutionalized in endemic countries and based on systematically collected data. Key stakeholders need to be identified early and engaged in the process, while improved communication is needed on all levels. Although malaria drug policy change is often perceived to be a daunting task, using these and other proven strategies should assist endemic countries to tackle this challenge in a systematic fashion that ensures the development and implementation of the rational malaria drug policy.

Artemisinin-based combination therapy reduces expenditure on malaria treatment in KwaZulu Natal, South Africa

INTRODUCTION

There is growing international evidence that artemisinin-based combination therapy (ACT) is one of the few effective measures available to 'Roll Back Malaria'. However, concerns about the costs and affordability of ACT are obstacles to its widespread implementation. This paper explores some economic aspects of the implementation of artemether-lumefantrine (AL) to replace sulphadoxine-pyrimethamine (SP) in the KwaZulu Natal (KZN) province, South Africa.

METHODS

Recurrent and capital costs for malaria treatment were compared at baseline and post-intervention for nine clinics and a sentinel rural district hospital. Changes in the unit costs of, and total expenditure on, malaria services were calculated and the cost effectiveness of AL relative to SP was assessed.

RESULTS

The number of outpatient malaria cases and inpatient admissions both declined by 94% between 2000 and 2002. After accounting for the role of concurrent improvements in vector control, it was conservatively estimated that 36% of the decline in outpatient cases and 46% for inpatient admissions was attributable to changing the first-line drug to AL. Although AL is considerably more expensive than SP, its improved cure rate and reduced malaria transmission resulted in an estimated 201,065 US dollars cost saving in 2002 alone for the subdistrict studied.

DISCUSSION

In the context of effective vector control and low efficacy of existing monotherapy, ACT can reduce total expenditure on malaria services. However, the relevance of these findings requires careful consideration in countries with currently effective treatment policies and higher intensity malaria transmission.

[Post-transfusion malaria: is the risk irreconciliable with biological silence?]

Despite the relatively high frequency of imported malaria in metropolitan France, the transmission of malaria by transfusion is exceptional. The screening of donations to determine those at risk is performed by an interview, and by the testing of serology for defined groups of donors. However, the exclusion of a candidate 'at risk' as a blood donor, by a pre-donation interview, is not completely mastered and the discrimination by biological examination lacks sensitivity, as much for methodological reasons as for reasons linked to the complex parasitic pathogenic agent (Plasmodium ssp.), as for the specific host defence system. The risk of introducing an unsafe-potentially dangerous (transfusion-transmitted malaria is often lethal)-element into the transfusional circuit is not completely covered. Is serology testing the most adequate test to avoid the risk of infected donations, in particular by Plasmodium falciparum; what are the alternatives and what will be the eventual added-costs of the biological qualification of such donations? The transfusional risk linked to Plasmodium seems, however, to be reduced to a minimum, concerning the circulation of plasma, which could represent an alternative for donors at real risk (rare) and those with a supposed risk (relatively numerous).

Is combination therapy for malaria based on user-fees worthwhile and equitable to consumers? Assessment of costs and willingness to pay in Southeast Nigeria

OBJECTIVES

To examine the equity implications of the costs of an episode of malaria, the benefit/cost ratios of using two artemisinin-based combination therapy (CT) from the consumers' view and inequities in willingness to pay (WTP) for CT.

METHODS

A cross-sectional survey was conducted in Southeast Nigeria, where there is a moderate to high level of malaria resistance to chloroquine and sulfadoxine-pyrimethamine formulations. WTP was elicited from respondents using the bidding game (BG) and the structured haggling technique (SH). A socio-economic status (SES) index was used to examine the level of inequity in the key variables. In the benefit/cost ratios, the average cost of CT in Nigeria and price of Coartem were, respectively, used as the cost inputs while the mean WTP was the measure of benefit. Multiple regression analyses were used to determine the validity of the WTP estimates.

RESULTS

More than 90% of the respondents were willing to pay for CT. The mean WTP in the BG was 301.1 Naira while it was 438.0 Naira in the SH. People in the highest SES quartile (Q4) were more willing to pay for CT than the lowest SES quartile (Q1). In the regression models, the SES quartiles were significantly related to levels of WTP. The benefit/cost ratios were higher in the SH group, and the ratio was only more than 1 using Coartem in only the SH group. The Q1 groups had the least benefit cost-ratios but the trend of SES differentials in benefit/cost ratios were not statistically significant in the BG group but was in the SH group.

CONCLUSION

CT based on user-fees may not be worthwhile and equitable because there are economic and equity constraints to its wide-scale use. Benefit/cost ratios depend on the type of questions that were used to elicit WTP. Governments and donors should be willing to commit funds to make CT affordable to the poor consumers for the intervention to be used to significantly reduce the burden of malaria.

Averting a malaria disaster in Africa--where does the buck stop?

The serious threat posed by the spread of drug-resistant malaria in Africa has been widely acknowledged. Chloroquine resistance is now almost universal, and resistance to the successor drug, sulfadoxine-pyrimethamine (SP), is growing rapidly. Combination therapy has been suggested as being an available and potentially lasting solution to this impending crisis. However, the current cost of combination therapy, and especially that of artemisinin combination therapy (ACT), is potentially a serious drawback, even if a significant part of its cost is passed on to the end-user. If the question of cost is not successfully addressed this could lead to adverse results from the deployment of combination therapy as first-line treatment. These adverse effects range from an increase in potentially fatal delays in infected individuals presenting to medical services, to exclusion of the poorest malaria sufferers from receiving treatment altogether. Urgent steps are needed to reduce the cost of combination therapy to the end-user in a sustainable way if it is to be usable, and some possible approaches are discussed.

A cost-effectiveness analysis of three antimalarial treatments for acute, uncomplicated Plasmodium falciparum malaria in Mumbai, India

BACKGROUND

Malaria is a major public health problem representing 2.3% of the overall global disease burden. The cost of treatment of malaria continues to rise as older drugs and insecticides become less effective and are replaced by more effective, but also more expensive products.

METHODS

A post-hoc pharmacoeconomic analysis (direct and indirect costs only) of three antimalarials, chloroquine, mefloquine and co-artemether, was carried out to address the problem of switch to a more expensive first-line antimalarial in the face of growing chloroquine resistance.

RESULTS

From the perspective of a large public hospital, it was seen that in an area of high grade chloroquine resistance, the total expenditure on patients who fail chloroquine would exceed the excess expenditure on mefloquine when the RII + RIII resistance exceeded 9%.

CONCLUSIONS

Switch to a more expensive drug like mefloquine as a first-line option would be cost-effective when the moderate-severe chloroquine resistance exceeded 9%.

Malaria and property accumulation in rice production systems in the savannah zone of Côte d'Ivoire

Irrigation stabilizes agricultural production and hence improves farmers' living standards and conditions. The permanent presence of water may, however, increase the burden of water-related parasitic diseases and counter the economic benefits of irrigation by reducing farmers' health. The purpose of this study was to assess the impact of malaria on farm household property, beyond the health risk (studied elsewhere). The research question was: by weakening individuals, does malaria reduce productive capacities and income workers, and consequently limit their property accumulation? To test this hypothesis, we use data on property (farming equipment, livestock and durable consumer goods) and Plasmodium falciparum indicators generated by a study carried out in 1998 in the Ivorian savannah zone characterized by inland valley rice cultivation, with a sample of nearly 750 farming households. Property is influenced by many factors related to the size of the family, the area under cultivation and high parasite density infection rate of P. falciparum. A significant negative correlation between high-density infection rate and the property values confirms that by reducing the living standards of households, malaria is a limiting factor for property accumulation.