Malariologist and Programme Manager, Osun State Malaria Elimination Programme, Dr Olufemi Oroge, talks to BOLA BAMIGBOLA about the need for improved investment in malaria control in Nigeria
What is malaria?
Malaria is a parasitic infection caused by the plasmodium species. The parasite is picked from an infected person by mosquitoes and transmitted to a healthy person who is bitten later by the already infected mosquito. The most common symptom is fever, which may be accompanied by other non-specific symptoms such as headache, body aches, joint pains, and vomiting, to mention a few. It is important to note that these symptoms can be experienced in several other illnesses and are not definitive of malaria. A confirmatory test must be done before commencing treatment with an antimalarial drug.
Is the human immune system capable of fighting malaria without drugs?
Yes, at least to a certain extent. When the immune system of a person is competent, it can fight the malaria parasite and greatly suppress its activities, but may not completely clear the parasite. This is especially the case with persons who live in malaria-endemic areas, that is, areas where malaria transmission occurs all year round, such as we have in most parts of Nigeria. The flip side is what happens in people who are not immunocompetent, people who are incapable of mounting appropriate resistance to an invading organism.
What is responsible for an individual’s inability to mount resistance to malaria?
This can be as a result of some drugs or chronic illnesses. Also, children who are under the age of five years are still in the process of optimising their immune systems, and may not be able to mount the required immune response. So also are people who don’t live in malaria-endemic areas, who have not had the required exposure that could help them develop a strong immunity against malaria.
What happens if these categories of people get infected?
If these categories of people get infected with the parasite, they are at risk of developing severe malaria, which could be fatal.
Going by your earlier explanation, is it correct to say malaria affects Africans and Europeans differently in terms of survival rate?
If both are subjected to the same environmental conditions long enough, differences in malarial survival between an African and a European may not be significant. I say this despite the belief that the AS genotype evolved as a protective response to malaria, and the genotype is found majorly in Africa. The key determinants of survival in a malaria infection are the acquisition of herd immunity and access to prompt diagnosis and effective treatment.
If a European lives in a malaria-endemic environment long enough to acquire immunity against malaria, their chances of survival may not be significantly different from that of the Africans they live with. If a European who is not immune comes into endemic Africa and gets infected, and he has access to prompt and effective diagnostic and treatment services, his chance of survival is excellent. Don’t forget that there are effective preventive interventions that can also be taken advantage of.
What happens to an African that probably has stayed out of the continent for a very long time and upon return gets infected?
If an African who was immune to malaria travels to Europe and lives there long enough to lose the immunity against malaria because they are no longer exposed to the parasite, but gets infected again, they become very vulnerable, like any other European.
The survival rate of Nigerians against malaria appears to be high. Is there a medical explanation for that?
It is not just Nigerians, but any other African country where malaria is prevalent. The ability to survive malaria is better and can be traced to the herd immunity that is obtainable in those places due to high malaria transmission. Improved access to malaria preventive, diagnostic and curative services continue to improve malaria survival. Having said this, it is important to note that many Nigerians are still dying from malaria.
According to the World Health Organisation’s world malaria report, Nigeria accounts for 31.3 per cent of all malaria deaths worldwide. The implication of this is that close to 200,000 people may have died from malaria in 2021 alone. If we compare this with all covid-related mortalities which from 2020 till date are probably less than 5,000, it will help to appreciate how massive this malaria mortality figure really is.
On the contrary, I think Nigerians have been very unlucky. Nigeria has been unlucky to continue to lose hundreds of thousands of lives to malaria on an annual basis, and individuals, families and the nation at large losing billions of naira annually to malaria treatment and lost productivity. It is a shame that we have not been able to truly identify and accept what our challenges really are, and to dedicate our best efforts to tackling them. If we had addressed malaria, which is one of our major health problems the way we addressed Covid 19, which you can say we were lucky with, the story would be different today.
What is the country not doing correctly in tackling malaria?
The problem is that we don’t put our money into solving our problems. Most of our public health interventions are supported by foreign donors, and you may forgive them if they modify their funding based on what they consider important. Nigeria is unlucky not to be getting anywhere near pre-elimination, let alone elimination. The National Malaria Elimination Programme needs a lot more investing in.
Is there anything like a malaria infection reaching the brain?
Yes, there is. It is called cerebral malaria. It is one of the manifestations that are categorised as severe malaria. There are five plasmodium species that infect man, and the most vicious of them is the plasmodium falciparum, causing severe malaria more than any other species. According to the Nigeria Malaria Indicators Survey 2021, it is the cause of 91 per cent of all malaria infections in Nigeria. It can cause red blood cells to stick together in the small blood vessels in the brain, leading to their blockage and inflammation of the surrounding brain tissue. This can manifest in symptoms such as convulsions, confusion, varying degrees of unconsciousness, and even death. With prompt and effective treatment, many recover fully, but some persons may not regain their full nervous system functions.
How does malaria affect people according to their blood group?
The well-known blood groups are the A, B and O groups. Although the mechanisms by which they influence malaria infections are not well understood, people in the O group are thought to be at a greater risk of severe malaria due to plasmodium falciparum infections, while those who carry group A are less susceptible. The Duffy blood group is also important. The Duffy antigen that characterises this group is necessary for another species of the parasite called plasmodium vivax, to enter the red blood cells. People who are Duffy-negative, that is, that do not have this antigen, cannot be infected by plasmodium vivax. Most people in Sub-Saharan Africa are believed to be Duffy-negative, and are, therefore, incapable of being infected by the species.
What are your thoughts about the emergence of a vaccine for malaria?
The theme for this year’s World Malaria Day is, ‘Time to deliver zero malaria: invest, innovate and implement’. We have spoken about the need for improved investment in malaria control. The malaria vaccine development is a great example of innovation. Innovations can help us get around challenges in equitable and less expensive ways. Vaccines have been described as the most cost–effective public health interventions, and we expect the same effect in malaria control with the introduction of malaria vaccines.
The RTS,S vaccine, with the trade name, mosquirix, had been in the pipeline for a long time and a good deal of evidence is available on its effectiveness and safety. It has been piloted in Kenya, Ghana and Malawi with impressive results, and approved by the WHO in 2021, but while we were awaiting its widespread adoption by nations, another vaccine, R21 came up.
Are the two vaccines the same?
It appears that the technology adopted by the newer vaccine allows it to stimulate a more intense antibody response, thereby posting fairly higher efficacy figures. It is argued if the difference between the effectiveness of the two is significant. Nigeria has, however, adopted the R21, and it appears that a major reason for that choice was the potential to get a larger number of doses in a relatively short time. The vaccine is expected to be delivered through the existing platforms for routine immunisation.
You spoke earlier about the National Malaria Elimination Programme and advocated a lot more investment. Is it possible to eliminate malaria?
It is part of the solution, but it is not going to be a silver bullet. There is an army of interventions that are being deployed across Nigeria for example, and based on epidemiologic stratifications. Such interventions can vary from one geographical location to another. And with wide variations in regional prevalence of malaria, from 2.6 per cent in Lagos to 49 per cent in Kebbi State, there has been no place for a one-cap intervention that fits all.
How is the vaccine expected to be administered?
The vaccine is expected to be given to children from the age of five months to 36 months. It does not confer lifetime immunity, and additional three booster doses may be required. So obviously, it is to help reduce the incidence of severe malaria and therefore death in children. While many children may be prevented from having malaria, some may still come down with malaria after taking the vaccine, but the chances of such infections being life-threatening are greatly reduced.
The vaccine is expected to add to the strength of existing interventions such as insecticide-treated nets use, indoor residual spraying of insecticides, perennial malaria chemoprevention, seasonal malaria chemoprevention and intermittent preventive treatment of malaria in pregnancy.
How does malaria affect a pregnant woman and her unborn baby?
Malaria affects both the pregnant woman and the unborn child. It is a major cause of anaemia, in children and pregnant women. When a pregnant woman has malaria and suffers severe anaemia, it is not just the red blood cells alone that are affected, but indeed other bloodlines, including white blood cells and platelets, too. She may be at great risk of dying from excessive bleeding at delivery because the platelets that help with blood clotting are deficient.
The unborn child is at constant risk at all stages of pregnancy when the mother has malaria, even when it is not obvious that she is infected. It could lead to miscarriages early in pregnancy, and when it does not, it could retard the growth of the foetus, and when this happens early enough to affect the developing brain, the impact can be irreversible throughout life, after the child is born. The parasite impairs the proper functioning of the placenta, which includes delivering nutrients from the mother to the foetus. This makes it consistently undernourished, with the potential for its death in the uterus, a stillbirth, or the delivery of a very low birth-weight baby. A low birth weight itself is the highest risk of a baby dying within the first 28 days of life.
Is it true that certain herbs are effective in treating malaria?
Some herbs are certainly effective in the treatment of malaria. Today, the globally recommended drugs for the treatment of malaria are the Artemisinin-based combination drugs (ACT). The artemisinin that is the bedrock of this drug combination is an extract of a herb that is native to South-East Asia. Quinine, which was the drug of choice for malaria treatment for many years in the past, is also a plant extract.
This knowledge, however, does not give anyone the liberty to indulge in taking unconfirmed, and unprocessed herbs at the expense of their health.
Not only have the examples of herbs I have mentioned above been confirmed to affect the parasite, but the specific active molecules responsible for the effect have also been identified, isolated from other molecules and plant alkaloids, and extracted in their purest forms. Determination of doses and drug trials to determine safety, side effects, and levels of effectiveness have been established for each of them. You’ll agree with me now, that it is not enough that a herb has some effect on the malaria parasite, you need to take just what you need out of the herb and understand the full profile of the active molecule as well as the possible side effects. Many people have indulged in herbs to the irreparable detriment of their kidneys and liver.