Malaria is a major public health problem in sub-Saharan Africa. Lately, scientists have been attempting to develop malaria vaccines that are appropriate for Africa. Prof WENCESLAUS L. KILAMA is the managing trustee of the African Malaria Network Trust (AMANET) formed in 1995 to plan and conduct malaria vaccine trials on the continent. He spoke to ZEPHANIA UBWANI

How would you describe malaria's status as a public health problem in Africa?

Malaria constitutes the greatest shackle to Africa's socio-economic development. Of the approximately 500 million cases and more than one million worldwide malaria deaths experienced annually, 80 to 90 per cent occur in Africa south of the Sahara.

Malaria in most countries in the region is by far the leading cause of health-institutional attendances, admissions and deaths and the situation is deteriorating. Furthermore, malaria anaemia may call for blood transfusions, thus exposing malaria patients to deadly HIV infection.

Since children under five years of age and women, particularly in their first and second pregnancies, are the most vulnerable groups to malaria, the disease is a major cause of the intolerably high rates of under-five and maternal mortality rates found across sub-Saharan Africa.

Why do you and other health researchers maintain that malaria is the leading cause of poverty on the continent?

It is not the scientific researchers like us alone who see the disease as a major cause of poverty. World class economists have highlighted malaria's annual direct and indirect costs to Africa, estimated at $12 billion per annum. They maintain that malaria is responsible for a reduction of 1.3 per cent in national economic growth rates.

Malaria is, therefore, a major cause of poverty in Africa. Furthermore, short-term visitors to Africa including consultants, guest researchers, businesspersons, investors and tourists lack protective malaria immunity and, therefore, are highly vulnerable to the disease, which may adversely affect the flow of foreign exchange earnings and investments.

What have been the major control strategies and why have they failed?

The cornerstone of malaria management in Africa is early correct treatment which, unfortunately, has been threatened by drug resistance. Since the 1940s, chloroquine [CQ] was the leading anti-malarial drug until the late 1970s, when CQ resistance was first confirmed in East Africa. It has now spread across the continent. In much of East Africa, CQ is no longer advocated for use in malaria treatment. As a result CQ was replaced by sulfadoxine/pyremethamine (SP).

Unfortunately, resistance to SP has quickly developed. The current trend is to shift to artemisinin combination therapy (ACT), which is expensive and ill-affordable for most malaria-prone communities.

How far has the search for malaria vaccines gone in Africa?

Over the past three decades, there has been considerable interest in research and development of malaria vaccines. The research results obtained have revealed that malaria vaccine candidates would differ not only in their biological properties but also in their eventual applications: pre-erythrocytic stage vaccines, also called sporozoite vaccines, would generally prevent malaria infection, asexual malaria vaccines (blood-stage vaccines) would prevent the disease, and the sexual stage (gametocytes) malaria vaccine candidates, which are also referred to as transmission blocking vaccines, would block malaria transmission.

An examination of the malaria vaccine development process, however, reveals that all malaria vaccine discoveries, patenting and pre-clinical tests are undertaken in developed countries. Only products that are safe in very preliminary testing are tested in Africa. Almost invariably, such testing is only done at institutions that have strong historical links with northern institutions. Moreover, foreign researchers are the principal investigators and therefore earn the accolades.

What has AMANET done to help develop a vaccine?

AMANET initially started as AMVTN in 1995 with the primary goal of preparing the continent in planning and conducting malaria vaccine trials. However, due to the expanding goals in malaria interventions, AMVTN was succeeded by AMANET in 2002 to reflect the widened scope that incorporates a broad and integrated approach in the fight against malaria that include anti-malarial drugs and vector control, among others.

AMANET has spearheaded the training of African scientists, preparing them for more meaningful participation in vaccine and other trials. Moreover, such training, which unfortunately is not provided in regular university curricula, will assure stakeholders that the test products meet required international standards. We have mounted short term training in such areas as bioethics, good clinical practice (GCP), good laboratory practice (GLP), design and methodology in intervention trials, data management, molecular biology and immunology in malaria vaccine development, management and leadership of malaria research institutions, and more. In all, AMANET has trained close to 500 African malaria researchers.

Furthermore, AMANET sponsors an African initiative that aims at developing standardised immunological assays for validating malaria vaccine candidate antigens. Currently the initiative comprises a network of six countries: Burkina Faso, Gabon, Ghana, Senegal, Tanzania and Zimbabwe.

Among the cherished goals of AMANET is to have African-owned and African-led institutions undertaking malaria vaccine trials that are appropriate for Africans living in malaria-endemic areas. These vaccines must be effective, efficacious, acceptable and readily affordable.