Recommendations

9.1.1. Implications of the research findings into policy and actions

Tanzania mainland’s goal was to reduce the average country malaria prevalence to less than 1% by 2020 [1]. However, this country particularly leans on case management and long lasting insecticidal nets (LLINs), which are both threatened by resistance. There is an urgent need to make rational use of drug a real and sustainable objective. Investments are put in researching for new diagnostic tools and drugs (20% of the annual malaria research and development funding [285]), while those existing are not used to their full potential.

Based on our findings, we can draw the following recommendations for health authorities and policy makers in Tanzania:

 Use drug measurements to assess impact of interventions and programs

Measuring drugs in the frame of population-based and school-based surveys can, combined with questionnaires limited to a few questions:

- help understand the most important drivers of antimalarials consumption

- help targeting interventions in the locations where medicine use appears inappropriate [286]

- assess whether programs such as Intermittent Preventive Treatment of malaria in pregnancy (IPTp) are correctly implemented (when used in population-based surveys) - assist in decision-making to implement specific interventions and be used as outcome

indicator [287] to further assess the success and impact of the implementation

- combination of available technologies such as high performance platforms (LC-MS or LC-UV) with mapping and modeling [288] can enable the collection of the minimal needed data of good quality [285] and predict data where they do not exist.

 Use drug measurements to assess impact of interventions and programs

 Strengthen drug policy outside health facilities

 Target interventions towards high risks areas

 Target children at high endemicity and adults at low endemicity

 Prioritize health workers training

 Use of local capacities

 Increase consumer awareness

 Strengthen drug policy outside health facilities

The high prevalence of lumefantrine (LF) levels (more particularly at sub-therapeutic levels) and of the relating mutant parasites in the studied population challenges the rationale of increasing access to highly effective treatment such as ALu through private sector, without suitable use of diagnostic tools. More restrictive rules should be introduced to drug vendors, such as forbidding the sale of ACTs without prescription or without positive mRDT result. This should be done along with increased mRDTs roll-out with proper training and supervision.

Then, the relatively high proportion of adults self-treated with SP calls for a special attention on reinforcing the use of first line treatments, in Mwanza particularly. The supply of sulfadoxine-pyrimethamine (SP) outside health-facilities (HFs) for specific programs such as IPTp and IPTi should be forbidden due to the poor efficacy of this treatment.

 Target interventions towards high risks areas

By measuring antimalarials in the blood, we identified that drug pressure was higher in districts of high transmission and in most accessible locations. Such places should thus be targeted first.

 Target children at high endemicity and adults at low endemicity

In high transmission areas, children represent the major infectious reservoir [289]. Improved case management should especially be targeted towards children, not only for a positive clinical outcome, but also to control the spread of resistance. In lower transmission settings, since adults are the major drivers of transmission [289], the use of recommended first-line efficacious drugs in adults should be promoted in the perspective of pre-elimination [3].

 Prioritize health workers training

The majority of febrile individuals seek care outside HF. Proximity of good quality health care should be improved by training dedicated community health workers (who do not have any incentive of selling more drugs, unlike drug shops). In HF, health workers should be better trained and their ability in performing mRDTs should be assessed on a regular basis. Clinicians should also understand the stake of treating according to the test results.

 Use of local capacities

Resources should be used in developing local capacities, in terms of human resources and technology platforms. Laboratory technicians could then be involved in surveillance activities ranging from parasite surveillance, resistance surveillance and drug assessment in the population. This could also be applied to other infectious diseases [277].

 Increase consumer awareness

Behavior change from the consumer side is also paramount in order to achieve rational use of antimalarials and other antimicrobials. Interventions that increase awareness of multiple causes of fevers are needed to support the new rationalization for malaria treatment represented by parasitological diagnosis [290]. For example, radio, sms platforms could be used or messages could be given to children at school [3].

In our study, many people tested positive did not have drugs in their blood. The importance of treatment adherence should be emphasized using logos on drug boxes or in drug shops and by asking patients to take the first dose under observation [194]. Poor adherence has an effect regarding clinical outcome, but also in the selection of mutant parasites as it leads to sub-therapeutical drug concentrations.

9.1.2. Recommendations for future research

 Choose the appropriate study design

In order to assess the impact of an intervention in a comprehensive manner, its effect should be evaluated both at HF level and in the community to see whether results obtained from HF surveys correlate with measures obtained in the population. Moreover, surveys should be conducted at repeated points in time to assess the sustainability of the effect, and in heterogeneous malaria transmission settings and heterogeneous proximity or easiness of transports to the HF and drug stores.

 Use of more advanced mathematical and statistical methodologies

The use of stochastic individual-based models of malaria transmission could simulate the prevalence of fevers that are due to malaria and thus the number of individuals that should have antimalarial detected in the blood. The simulation models can be parameterized using the survey data such as malaria endemicity, demographics, measures of access to care, use of

 Choose the appropriate study design

 Use of more advanced mathematical and statistical methodologies

 Monitor drug pressure and resistance

 Use dried blood spot in a broader antimicrobial stewardship effort

 Improve knowledge on drug inhibitory concentration and distribution

 Search for new drug combinations



diagnosis and treatment regimens and outputs from the simulations compared with field data.

Furthermore, understanding the mechanism of drug resistance both at individual and population level is crucial in order to embrace the dynamic of resistance [69]. The population component needs to be tackled using more advanced statistical methodologies such as bayesian statistics and mapping and taking into account other important geographical or climate factors which could have an influence on resistance development and spread [291].

Knowledge of special characteristics and predictors of diseases has proven to be valuable tools to assist health authorities in adapting appropriate and targeted interventions [291,292]. This analysis has already been initiated in collaboration with Dr. Penelope Vounatsou, Head of the Bayesian Modeling and Analysis group at the Swiss TPH.

 Monitor drug pressure and resistance

Understanding, tracking and mapping resistance is essential to understand how it spreads.

Drug pressure, because it is linked to resistance, could thus be measured alongside with antimalarial susceptibility testing [277].

In our study, we did not know whether the parasites detected in our samples had been selected during the previous treatment or if they were new infections. Genotyping of a highly polymorphic gene such as pfmsp2 [96] could define the genetic diversity of the infection and help distinguish reinfections from primary infections and should be used to understand the role of residual drug levels on parasite resistance.

 Use dried blood spot in a broader antimicrobial stewardship effort

Decrease in antimalarial use often goes hand in hand with an increase in antibiotic prescription [182,293]. For this reason, DBS should be used to simultaneously measure antimalarials and antibiotics to better understand the dynamic of antimicrobial consumption. A LC-MS/MS method for the analysis of the 12 most frequently used antibiotics in Tanzania (namely amoxicillin, metronidazole, ceftriaxone, trimethoprim, sulfamethoxazole, cephalexin, ciprofloxacin, doxycycline, chloramphenicol, erythromycin, penicillin V and G) in DBS has been developed by a Master student in Pharmacy [294] in the frame of the present thesis. This method is planned to be used in a new project aiming at assessing antimicrobial drug pressure at the population level and evaluating the impact of antibiotic stewardship intervention on antimicrobial drug pressure [295]. The spatial distribution of antimalarial and antibiotic use in the population will then be mapped and used to re-inforce and better target antimicrobial stewardship interventions.

 Improve knowledge on drug inhibitory concentration and distribution Few reliable and reproducible information on the minimum inhibitory concentrations (MIC) of the studied drugs are available in the literature. Furthermore, after correlating LF concentrations in DBS and plasma, we realized that LF distribution inside the red blood cells is minimal. More extensive research on the MIC and the distribution of the drugs inside the erythrocytes (where drugs inhibit the intra-erythrocyte development [87,88]) should be conducted to better assess parasites susceptibility to drugs.

 Search for new drug combinations

We confirmed the limitation of combining short half-life and long half-life compounds. Studies should examine possibilities of combining drugs with shorter and similar half-life as well as using triple combinations therapies to prevent resistance.

9.2. Conclusion

We developed a sensitive LC-MS/MS method for the simultaneous analysis in DBS of the major partner drugs used in ACT combinations. This methodology was suitable for field studies and enabled us to collect objective and reliable data to illustrate the complex interplay between parasite prevalence and resistance, individual factors such as age and health seeking behavior as well as diagnosis and treatment practices. We were able to identify the principal determinants of drug use, which could be used in the future in malaria control (to assess access to care as well as diagnostic and treatment policies implementation) and surveillance (along with parasite resistance surveillance for example). We also demonstrated that the presence of low LF concentrations in the blood of individuals surveyed in the community was associated with the presence of parasites harboring markers of drug resistance. Despite efforts made to improve access to diagnostic tools, there is still a high drug pressure in the population. A better targeted use of antimalarials in favor of parasitologically confirmed malaria cases only should be urged in order to stop the spread of resistance. To that aim, the WHO guidelines of systematic diagnosis and treating upon results is an essential guideline to be followed and there is a need to support the use of mRDTs use with proper training in the public and in the private sector.

This observational work was a first step in the evaluation of drug pressure in the community, using reliable tools to have a deeper understanding of the relationship between drug pressure and parasite resistance at population level. It is now time to integrate available advanced technologies and statistical tools such as Bayesian statistics and mapping to create good quality data and predict data when they are not existing. Modeling could also be used as a pro-active approach to predict the effect of interventions on drug pressure.

The amount of drug pressure in the population should seriously be considered as Tanzania wants to progress towards malaria pre-elimination. High prevalence of individuals with drug in the blood (such as during mass drug administration) is only recommended in settings approaching interruption of transmission [296], where the risk of re-introduction of infection is minimal [297]. In other transmission settings, the temporary prophylactic effect of long half-life compounds provides a significant selective pressure for the emergence of drug resistance, which threatens the sustainability of gains in malaria control and prospects for elimination [298]. Strategies to stop the expanding resistance to artemisinins and partner drugs are urgently needed [273] and this starts by avoiding parasite exposure to a single selective agent, which is the central principle of resistance management [298].