THINKING ALOUD: A potent weapon against malaria lies somewhere in Kibaha

Credit should be given where it is due. I give credit to the fourth phase government for being instrumental in building the anti-larvicidal factory in Kibaha with the help of the Cuban government.

But the factory would have remained another white elephant had President John Magufuli not intervened.

Recently during his tour of Coast Region tour, he directed every district to buy the larvicidal and payment be made directly by deducting monies from district accounts. Thus credit also goes to President Magufuli.

The question remains: why didn’t district executive directors buy this important item from the factory in the first place? My guess is that they were ignorant and needed education about what this was all about. This article is therefore meant to shed some light on this larvicidal solution because if they are still uninformed, they will either not bother to use the product or will use it inappropriately.

The solution from the Kibaha factory is a form of biological control or “biocontrol”, which is the use of bacteria to kill vector larvae without generating adverse ecological impact. Specifically, this form of biocontrol uses dead spores of the soil bacterium Bacillus thuringiensis, especially Bt israelensis (BTI), and this interferes with larval digestive systems.

It can be dispersed by hand or dropped by helicopter in large areas. BTI loses effectiveness after the larvae turn into pupae because they stop eating. Once this chemical is ingested by the larvae, it kills them, thus the population of adult mosquitoes is reduced and along with the potential to transmit malaria parasites.

Having said this, let me clarify that using the Kibaha larvicidal solution alone cannot control malaria. What is needed is integrated vector management (IVM) and integrated malaria control (IMC).

IVM reinforces linkages between health and the environment, optimising benefits to both. It is a dynamic and still-evolving field. IVM strategies are designed to achieve the greatest disease-control benefit in the most cost-effective manner while minimising negative impact on ecosystems (e.g. depletion of biodiversity) and adverse side effects on public health.

Possible health risks range from acute exposures to pesticides and their residues to bioaccumulation of toxic chemicals and development of vector resistance to some widely used pesticides and drugs.

Rather than relying on a single method of vector control (e.g. chemical spraying), IVM stresses the importance of first understanding the local vector ecology and local patterns of disease transmission, and then choosing the appropriate vector control tools from the range of options available.

These include environmental management strategies that can reduce or eliminate vector breeding grounds altogether through improved design or operation of water resources development projects; and the use of biological controls that target and kill vector larvae without generating the ecological impact of chemical use. At the same time, when other measures are ineffective or not cost effective, IVM makes judicious use of chemical methods of vector control such as indoor residual sprays, space spraying and chemical larvicides and adulticides.

These approaches reduce disease transmission by shortening or interrupting the lifespan of vectors. IVM also provides a framework for improved personal protection/prevention strategies that combine the use of environmental management tools/physical barriers with chemical tools for new synergies, e.g. insecticide-treated nets (ITNs).

The use of insecticide-treated bed nets has shown to substantially reduce child and infant mortality.

A word of caution: IVM is not a panacea for the control of malaria, which is responsible for approximately 11 per cent of the total disease burden in Africa, or other vector-borne diseases in general.

Along with early effective disease diagnosis and prompt treatment, the careful monitoring of disease incidence is important in order to fine-tune and improve vector control strategies.

Finally, community support and increased individual awareness are necessary to facilitate a more integrated approach to vector control/prevention and disease care/treatment measures and to ensure their sustainability.

The malaria situation in Tanzania is definitely getting better, mainly due to better management of control efforts by the National Malaria Control Programme (NMCP) at the Ministry of Health. There has also been increased funding of control activities not only in Tanzania but globally. However, sustaining this tempo and these achievements is a challenge.

NMCP should now visit every district to impart the needed education, especially how to appropriately use the Kibaha larvicidal solution and in what situations should this be applied.

Cementing success with sustained high coverage of existing control measures and embarking on elimination are next opportunities. Not doing this would easily allow malaria to re-establish itself and reset morbidity and mortality back to where they were.

Understanding the systems needed for sustained control and the next interventions en route to elimination will be important, but it is the growth of country and local partnerships and their incentives that will make or break the opportunity for continued success in malaria control.