Sunday,September 22,2019 06:55 AM

Fight to end malaria using DDT 

By Admin

Added 10th June 2019 10:19 AM

Malaria is highly endemic in 95% of the country with approximately 90% of the population (estimated at 32 million people) at risk.

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Justus Nuwajuna Kamuhanda

Malaria is highly endemic in 95% of the country with approximately 90% of the population (estimated at 32 million people) at risk.

By Justus Nuwajuna Kamuhanda

When considering the budget of financial year 2019/2020 about sh1.1trillion allocated Ministry of Health (MoH), Ugandans are smiling like Gonja’s seller knowing that the enemy Malaria and other vector diseases are finished. 

Malaria is Uganda’s leading cause of morbidity and mortality. According to MoH, malaria accounts for 25-40% of outpatient visits to health facilities and has historically been responsible for nearly half of inpatient pediatric deaths. 

Malaria is highly endemic in 95% of the country with approximately 90% of the population (estimated at 32 million people) at risk.

The remaining 5% of the country consists of unstable and epidemic-prone transmission areas in the highlands of the south and west, along the eastern border with Kenya, and the northeastern border with South Sudan. 

Malaria transmission is persistently high in some areas of northern Uganda. 

Malaria prevalence among children 0 to 59 months of age by microscopy in the 2009 Uganda Malaria Indicator Survey (MIS) showed that 42% tested positive for malaria. 

Prevalence was higher in rural areas than in urban areas (47% versus 15% using microscopy) and ranged from 5% in Kampala to 63% in the mid-northern region.

However, fighting malaria on one part is fighting environment on another part: should we use  Dichlorodiphenyltrichloroethane (DDT ) to protect present at the detriment of the environment by destroying present and future against the principle of sustainable development.

DDT was among the initial persistent organic pollutants listed under the Stockholm convention and continues to be used for control of malaria and other vector-borne diseases in accordance with its provision on acceptable purposes. Trends in the production and use of DDT were evaluated over the period 2001-2014.

The organochlorine DDT has been listed with the main objective to protect human health and the environment from persistent organic pollutants. (POPS)

The Convention aims to reduce and ultimately eliminate DDT but recognizes the acceptable production and use of DDT for disease vector control. 

DDT is one of the insecticides recommended by WHO for indoor residual spraying for malaria control.

In November 2009, Indoor Residual Spray (IRS) project by USAID under President Kaguta Museveni’s Malaria Initiative (PMI) begun in Uganda, and continue to be used in the northern districts of Uganda. 

Since then, the initiative has concentrated its support for IRS in ten northern districts: Kitgum, Agago, Lamwo, Pader, Amuru, Nwoya, Gulu, Oyam, Kole, and Apac. IRS was initially conducted with pyrethroids in all districts except Apac and Oyam, which were sprayed with DDT in 2008. 

Due to insecticide resistance to both insecticides, a change to carbamates was made in 2010. Targeted household coverage has been consistently high (above 90%). Implementation of Indoor residual spray in Uganda continues to face many challenges.

Malaria transmission is intense and perennial in nearly every region of Uganda. Interrupting transmission when the transmission season lasts for 10months of the year requires multiple rounds of spraying per year or the use of insecticides with long residual action.

The Initiative piloted the use of DDT in Apac and Oyam Districts and later to the almost all districts; however, its use was subsequently banned by a court injunction launched by organic farmers.

Though the court injunction was lifted, insecticide resistance monitoring studies revealed high levels of vector resistance to DDT.

Currently, the National Malaria Control Program, (NMCP) does not have a clear strategy for implementing vector control interventions. 

However, the GOU has indicated plans to make funding available to support some IRS and larviciding. A strategy is needed to provide clear guidelines on how the activities funded by the government of Uganda. 

Environmental effects

As a persistent molecule, DDT has low to very low rates of metabolism and disposition, depending on ambient temperatures. In tropical environments with high temperatures and solar radiations, DDT is less persistent than in temperature environments. 

It is degraded slowly into its main metabolic products DDE and DDD, which have similar physiochemical properties but differ in biological activity. DDT is emitted through volatilization and runoff.

It is more volatile in warmer than in colder parts of the world which, through long-range atmospheric transport, results in a net deposition and thus gradual accumulation at high latitudes and altitudes.

Loss through runoffs is low because DDT has along with an affinity for organic matter in soils and aquatic sediment, but is virtually insoluble in water.

Half-lives of DDT have been reported in a range of 3-7 months in tropical soils and up to 15 years in temperate soils. The half-life of each of its metabolic products is similar or longer. 

DDT readily binds with fatty tissue in any living organism and, due to its stability, bio-concentrates and bio-magnifies which increasing trophic level in food chains.

The half-life of DDT in humans is more than 4 years; the half-life of DDE is probably longer. DDT is highly toxic to insects, shrimps and fish absolutely affects the reproduction of wild birds through thinning of eggshells.

Most of the DDT and its metabolic products present in the global environment originate from its large scale use in agriculture and domestic hygiene in the past. Current use under the Stockholm Convention is allowed only for indoor spraying for disease vector control. 

Thus, use is much smaller than in the past. Nevertheless, DDT that is sprayed indoor may end up in the environment, even if it is sprayed on walls according to best practice. Little attention has been paid to this issue.

A simple modelling study predicted that 60-82% of DDT was physically removed from house walls within 6 months after spraying, but verification through the empirical study is needed. 

Data from Brazil, India, Mexico and South Africa suggested that higher levels of DDT are found in water or soil samples in areas with DDT residual spraying than in areas without spraying and Uganda having used DDT, we are likely to reflect the same data. 

Hope for Uganda

Uganda is a party to the Stockholm Convention having ratified it on 20th July 2004, with the main objective to protect human health and the environment from persistent organic pollutants (POPS) and the convention aims to reduce and ultimately eliminate DDT hence obliged to cooperate and DDT Register has been established under the Stockholm Convention in which countries are obligated to report their intention to produce or use DDT.

Every 2 years are regular meetings to evaluate the continued use of DDT for disease vector control was confirmed in the 2015 conference as per the Stockholm Convention.

A number of laws have been enacted by the Ugandan Parliament towards controlling such toxic substances such as:-

The national drugs policy and authority Act 1993, The agricultural chemical (control) Act 20, The atomic energy Act 2008, The national biotechnology and biosafety bill, the National Management Environment (NEMA) Act 2019, The occupational safety and health Act 2006-SI and The Toxic Chemical Prohibition and control Act 2016.

Also the government of Uganda has provided funds to the a Chemical Safety and Security project (CHESASE) to strengthen the Ministry of Gender Labour and Social Development Nationally (MGLSD) coordinated by Mr. Asimwe Alex under the supervision of Mr. Bigirimana Pius the permanent secretary to the ministry who also doubles as the chairperson a national authority called National Chemical Regulatory Authority whose membership among other include; the NEMA whose role is to make sure the toxic chemicals do not negatively affect our environment.   

Therefore as we jubilate that our malaria enemy is being reduced we need to take all measure to protect the environment and full range of known, available technologies and alternative to DDT have to continually be considered for use by Uganda in the malaria prevention and control efforts. 

Therefore my fellow Ugandans and our comrades in Uganda as we celebrate the budget week, the MGLSD and NEMA are mindful of chemical use and control hence Global production and global use of DDT have shown a modest decline.

The writer is a lawyer working with the Ministry of Gender Labour and Social Development (MGLSD).

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