By Mary Hearty
Children- particularly under the age of 5 years- living in settings with stable and high malaria transmission intensity are known to be at risk of developing severe malaria.
Moreover, it is estimated that every 200 children infected with Plasmodium falciparum, one of the malaria parasite species with the highest malaria transmission rate, at least two will develop severe malaria and that one of them will die.
In Ghana for instance, estimates from the World Health Organization (WHO) conducted in 2020 show that there were approximately 5 million cases of malaria, which resulted in an estimated 12000 deaths. Overall, malaria accounts for approximately 8% of under-5-mortality in the country.
Over one million children in sub-Saharan Africa have received the newly launched malaria vaccine, RTS,S which received WHO recommendation in 2021.
According to Dr. Henrietta Mensah-Brown, an expert in malaria biology and immunology and African Academy of Sciences (AAS) Fellow, the development of a multi-component vaccine that targets multiple stages of the life cycle of the malaria parasite including the invasion proteins may be a good strategy to help eliminate malaria.
This is because though effective, the current malaria vaccine RTS, S targets only one stage of malaria (liver stage). This is the stage following the parasites being released into the bloodstream.
Dr. Mensah-Brown suggests that understanding how malaria parasites invade the red blood cells to cause infection may be a good strategy to help eliminate malaria.
She explains that red cell invasion by malaria parasites is a crucial step in the life cycle of the parasite, where the parasites must invade the red blood cell in order to survive and maintain infection.
During the invasion process, the parasite produces proteins which its uses to irreversibly attach to proteins on the surface of the red blood cell to facilitate its entry into the red blood cells.
She further notes that the process of invasion is complex because several proteins are involved, making it difficult to target a single protein to prevent invasion, adding that there are multi-component vaccines at various stages of development at different research centres across the world.
Dr. Mensah-Brown adds that vector control measures such as use of insecticide-treated nets and inside residual spraying are very important as they remain critical in reducing the burden of malaria in children under five years.
These vector control strategies have worked in the past and can help reduce the incidence of malaria overall, she said.
In addition, the expert in malaria biology and immunology notes that community engagements and education are important because through these, community members can understand how and where mosquitoes breed to cause the disease.
“The risk of severe malaria infection is increased by factors such as lack of insecticide treated mosquito nets, living near stagnant water bodies and staying outdoors for extended periods at night,” Dr. Mensah-Brown said.
She further explains that several publications in Africa have shown that the risk of severe malaria in children is also increased by multiple socio-economic factors including the educational level of the parents, the type of housing and the occupation of the parents.
According to Dr. Mensah-Brown, severe malaria infection is multi-syndromic and often manifests as cerebral malaria, severe malaria anaemia and respiratory distress.
The distribution of these severe malaria syndromes varies by age across transmission intensities, and is influenced mainly by changes in community-level immunity patterns.
Furthermore, she says immunity to malaria is acquired over time, after multiple infections. And this is why children are more at risk because they lack immunity to help fight malaria infection effectively, and therefore the more severe forms of disease are found in children.