An important issue of Malaria-endemic countries is how to effectively prevent Malaria, while not harming the environment, contributing to environmental sustainability. The effect of malaria on the human race is obvious, since it is causing many deaths and suffering in the sub-Saharan population. What is not so obvious is the effect of malaria on the environment. Mostly relating to the organisms in the environment and biodiversity, malaria causes great disruption in the ecosystem.
One main way of preventing the spread of malaria includes indoor spraying of insecticides. Dichlorodiphenyltrichloroethane (DDT) is an example of this insecticide used for disease vector control. The main cause of the ecosystem and diversity disruption roots back to about 1940, when DDT was developed as an insect pesticide. The use of DDT is controversial because recent reports of high levels of human exposure from these indoor sprayings correlate with chronic health effects. Another issue with DDT is how more malaria vectors are becoming resistant to the toxic action of DDT, and in turn resistance is spreading to new countries.
Figure 1: Indoor spraying of DDT
(Stockholm Convention on Persistent Organic Pollutants, 2004)
The Stockholm Convention took place in 2004 with the purpose of elimination 12 chemicals or classes of chemicals, one of which being (DDT). The convention investigated the risks associated with 12 persistent organic pollutants (POP). Many POPs pose significant threats to human health and the environment and were addressed in the Stockholm Convention on Persistent Organic Pollutants treaty aiming to restrict and ultimately eliminate the production, use, release, and storage of POPs. This treaty became a law starting 2004, and over 90 countries joined by 2005. The main purpose of this treaty is to eliminate non-beneficial toxic POPs while transitioning from other POPs to safer alternatives (Stockholm Convention on Persistent Organic Pollutants, 2004).
The environmental concern regarding DDT use prevented DDT use in sub-Saharan Africa. Regardless of use or no-use, it was proven that DDT is found in small amounts in water, air, and soil. In other words, exposure to DDT is inevitable once it was released as a pesticide. Organisms can easily absorb DDT from the surrounding atmosphere and from the food they consume. When aquatic species consume DDT, it has shown to be heavily fatal. It leads to hyperactivity and dissolves membranes since DDT is soluble with lipids. This interferes with many membrane enzyme systems. Also, DDT accumulated in the body and affects species that prey on these fish. For example, many birds prey on aquatic species and are therefore prone to a lot of DDT exposure. Continuous exposure of DDT to birds has resulted in them laying eggs with thinner shells. This led to a decrease in certain bird population since many of the eggs were cracked during the early stages in the nests. This disruption to the ecosystem caused by DDT decreases biodiversity, which is an essential factor to preserve for a sustainable future (“DDT-A brief history and status”, 2012).
POPs have the ability to remain in the environment and in animal tissue, so POPs used prevalently for agricultural purposes 50-60 years ago are still affecting humans today. Not all POPs are harmful; however, many cause cancer and can cause damage to the nervous systems, reproductive systems, immune systems, or livers of animals. The issue with the 12 POPs addressed in this treaty is that they are highly toxic and persistent, lasting for years before degrading into less dangerous forms. They also evaporate and travel long distances through the air and through water, and can accumulate in animal fatty tissue. One of the most known POPs, is DDT, which was widely used during World War II to protect soldiers and civilians from malaria, typhus, and other diseases spread by insects. It continues to be applied against malarial mosquitoes in several malaria prone countries, especially in Africa (Van den Berg, 2009).
Indoor spraying of DDT is a relatively cheap and effective way of keeping malarial mosquitoes out and simply banning DDT could have an effect on human mortality due to malaria. As of 2011, DDT spraying is allowed for controlling disease vectors in accordance with the World Health Organization (WHO) recommendations and guidelines and also when locally safe, effective, and affordable alternatives are not available.DDT use in Africa has actually increased since the Stockholm Convention came into effect, but global use of DDT has slowly been decreasing (Stockholm Convention on Persistent Organic Pollutants, 2004).
Figure 2: Decrease in deaths caused by malaria due to the use of DDT and how drug resistance limits this decrease.
Greatest decrease in deaths in South Asia and Middle East, with potential improvements in Africa.
A rational drug policy, besides standardizing treatment protocols for an optimal case management, should aim at limiting the emergence and spread of drug resistance. Chloroquine resistance, now widespread in Africa, has resulted in increased malaria mortality and morbidity requiring a change to sulphadoxine-pyrimethamine in several countries. However, sulphadoxine-pyrimethamine resistance will probably spread more rapidly because of its prolonged half-life, determining a higher probability of selecting resistant strains. Drug combinations for the treatment of malaria might delay the emergence and spread of resistance (Moerman et al, 2003).
However, the implementation and use of combination treatment will be a major challenge for the health services at all levels. Most of the drugs currently used for combination treatment are not co-formulated, the only exception being artemether-lumefantrine. Also, the cost of such treatment will be much higher than current treatment and access to proper case management will be lower. Combination treatment might be more accessible to the local population if costs are subsidized by initiatives such as the GFATM.Furthermore, new and more affordable drugs could be developed by the Medicines for Malaria Venture (MMV), a research-and-development-focused partnership committed to developing new drugs on a regular basis while ensuring access to the most vulnerable groups (Moerman et al, 2003).
Many mosquitoes and other insects developed an immunity and resistance to DDT, allowing them to survive even after exposure. For obvious reasons, this did no help in trying to eliminate malaria cases. As a new tactic to overcome this situation, the Ethics Advisory Agency for the International Cooperation (ACECI) proposed in 2010 to produce anti-mosquito products using the plant cat cataria instead of DDT (Karirekinyana). This was first tested in Burundi, and they offered the Burundian government investments on providing sub-Saharan populations with mosquito repellents made from this plant. This project offered job creation as well as economic growth through trade of repellents in the vulnerable region and making products affordable and available.