Boosting the Impact of Seasonal Malaria Chemoprevention (SMC) Through Simultaneous Screening and Treatment of SMC-Children's Roommates in Burkina Faso

Malaria represents a major public health concern in sub-Sahara Africa. According to the World Health Organization (WHO) nearly half of the world's population is exposed to malaria infection causing 400 000 deaths yearly worldwide. In Burkina Faso like in most of sub-Sahara Africa countries, malaria remains endemic with peaks during raining seasons. To reduce the burden of the disease in the country, Burkina Faso has subscribed to the Roll Back Malaria initiative and adopted several malaria control measures including the use of artemisininin-based combination therapies as first line treatment since 2005, the intermittent preventive treatment for pregnant women, the wide-scale distribution of long-lasting insecticide treated net, and seasonal malaria chemoprevention (SMC) for children under five years old. However, despite the implementation of these multiple interventions, Burkina Faso is ranked among the top 10 countries carrying the highest malaria burden. For instance, in 2018, over 10 million clinical episodes and 4294 deaths were reported in the country.

In such context, new strategies to complement the existing ones or to improve their impact are urgently needed in order to reduce malaria transmission. The project we propose aims at improving the impact of Seasonal malaria chemoprevention (SMC) intervention to achieve best impact in malaria control and elimination. SMC is one of the largest and reliable malaria preventive measures recommended by WHO and is known to reduce malaria morbidity by 30 to 83%. It involves the administration of antimalarial drugs (Amodiaquine+Sulfadoxine-Pyrimethamine - AQSP) to children aged 3-59 months on a monthly basis during the high transmission season. In Burkina Faso, SMC is implemented nationally from July to October each year by the NMCP with the support of its technical and financial partners such as Global Fund, WHO, Malaria Consortium, PMI, UNICEF....). SMC was firstly implemented in 2014 in 6 of the 70 sanitary districts of the country. Few years later almost national wide coverage (except in Ouagadougou i.e. 60 over 70) was reached in 2018 and the intervention was adequately delivered by community health workers. Since the adoption of this strategy, data assessing the real-life impact of this intervention in the country are rare. In 2018, Druetz et al reported a protective effect of 62% highlighting the potential of this intervention for malaria control in Burkina Faso though this protective effect remains far below the highest threshold of 83% reduction of malaria incidence expected from SMC intervention. We anticipate that holding SMC campaigns in the context of the Covid-19 combined with the fact that some parts of the country are prone to insecurity may be challenging. However, it is important to stress that the year 2020 SMC campaign has been fully implemented in the study area without any disturbance related to the Covid and/or security issue. In addition, the study area, Nanoro is located at 85 km from Ouagadougou the capital city in the Central West Region of Burkina Faso where we have not experienced any particular security issues so far. With respect to research activities, the CRUN has no records of setbacks in fulfilling such activities due to security issues. All the research activities initiated before the insecurity onset have continued uninterrupted.

Furthermore, the burden of malaria in children under five years old suggests that the expected impact of this promising intervention is not achieved. Indeed, children under five years old represented the most affected population accounting for about 90% of malaria cases. RDT confirmed malaria cases in the country moved from 1 219 975 cases in 2016 to 1 487 954, and to 1 509 931, in 2017, and 2018 respectively. In view of the actual trend it becomes obvious that despite the implementation of this strategy, the burden of the disease and associated mortality is still very high in children under five years old in Burkina Faso, confirming that the expected impact from this intervention is not achieved. This raises questions about other hidden factors that can negatively affect the effectiveness of SMC intervention. At the same time, huge effort aiming at preventing human-vector contact were deployed such as the large-scale distribution of insecticide treated bed nets (LLIN). The latter are distributed on the basis of two individuals per unit. However, while most of the bedroom in rural setting in Burkina Faso are not adequate for the fixation of several LLIN, more than two individuals per room is commonly observed. In addition, the frequent mosquito bites before sleeping time and changing mosquito behavior becoming more aggressive before and after sleeping time is of concern. The latter could explain a persisting malaria transmission within a relatively close environment despite full coverage in LLIN.

Nevertheless, with regard to the infestation cycle, healthy humans are only infected via mosquitos if there are parasites reservoir (symptomatic and asymptomatic careers including sub-patent parasitaemia) around. Yet, there is no strategy aiming at protecting healthy humans from parasites reservoir. Under these circumstances, multiples humans sharing the same habitat (room, household) could continually entertain the transmission cycle despite adequate existing measures such as the use of LLIN. For instance, children under SMC coverage live closely with their family members e.g. mother, father, siblings and other relatives, who are not targeted by any specific interventions. According to the Nanoro health demographic surveillance system, an average of 3 inhabitants per household was observed. Published literature on sleeping behavior reported that children mostly sleep with their mother or with mother + sibling. Attempts to improve the impact of SMC intervention includes its extension to children under ten years old which showed promising results in Senegal. However, parents and elder siblings (over ten) not covered by the SMC (implemented either in under 5 or extended to under 10) sharing the same habitat could be parasites reservoir infecting continually the vulnerable group under SMC coverage. This is particularly important in a context of low coverage and compliance to ITN. Indeed, according to the household survey results in 2018 from the word malaria report, 54.5% of the population in Burkina Faso had access to ITN while only 44.1 had slept under ITN last night. This phenomenon of continual infestation of children from parents and elder siblings would obviously jeopardize the expected impact of the SMC intervention and the global effort to control the disease.

Finally, drug pressure, especially in wide scale community-based intervention such as SMC could lead to a selection of less sensitive mutant strains that could compromise the effectiveness of the intervention in a long-term period. Therefore, sustainability of any intervention relies on its selection pressure on parasite population which need to be closely monitored.