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Tanzania plans to use bacteria to eliminate mosquito larvae

Saturday April 06 2013
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In 1965, Cuba succeeded in eradicating malaria, largely through the use of chemical and biological insecticides. The country has pioneered research into the use of biological toxins to kill mosquitoes. FILE

Tanzania is building up its arsenal in the fight against malaria — one of the country’s biggest killers — by adopting, on a large-scale, new scientific technology. This technology involves using bacteria to poison mosquito larvae.

The government has already provided 75 per cent of the funding needed to complete a $22 million biolarvicide factory with a capacity of six million litres per year. The factory, located at Kibaha District in the Coast region of Tanzania, is expected to be complete by the end of the year.

The project, which was mooted in 2010, is a joint venture between the Tanzania government and Cuban state-owned firm Entrepreneurial Group Biological and Pharmaceutical Laboratories (Labiofam).

Malaria is the single biggest disease in Tanzania and is responsible for at least 40 per cent of deaths. Children under five years and pregnant mothers are the hardest hit by the disease.

Ninety-one out of 1,000 Tanzanian children do not live past their fifth birthday. Statistics show that Tanzania is spending about $240 million or a staggering 3.4 per cent of GDP annually to treat malaria. This suggests that of the $11.37 being spent per person per year on health, $2.14 is spent on treating malaria and its complications.

The World Health Organisation (WHO) reports that malaria is costing Africa more than $12 billion every year in lost gross domestic product (GDP), and could pull down GDP by as much as 1.3 per cent in countries with high levels of transmission.

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Over the long term, these aggregated annual losses have resulted in substantial differences in GDP between countries with and without malaria.

Malaria is the leading cause of morbidity and mortality in Kenya — about 34,000 children die annually from malaria-related causes, while a large number of pregnant women living in malaria endemic areas regularly suffer severe complications such as still-births and miscarriages, according to the Health Ministry.

In November last year, a breakthrough in the fight against malaria appeared to be close after the trials of a vaccine returned promising results. The trials were conducted in seven African countries including Kenya and Tanzania.

READ: Trial results create prospect of a malaria-free Africa

The trials saw one out of every three infants who were given the new RTS,S vaccine, develop immunity to malaria. RTS,S (the world’s first candidate malaria vaccine) reduces malaria by approximately one–third in African infants, according to the initial results of an ongoing large-scale Phase III trial, published in the New England Journal of Medicine.

ALSO READ: New plans to improve malaria vaccine

When compared with immunisation using a control vaccine, infants aged 6-12 weeks and vaccinated with RTS,S had one-third fewer episodes of both clinical and severe malaria and had similar reactions to the injection.

In most countries, education on the use of treated mosquito nets is being encouraged, with governments across Africa scrapping the import duty on nets and others encouraging local manufacturing of nets.

There are also efforts to seek different medicines for the disease, with those with the highest comparable efficacy levels being recommended for use by the WHO and national health departments in public and private health centres.

In East Africa, Kenya, Uganda and Tanzania have higher rates of malaria compared with Rwanda and Burundi, which are highlands. Rising resistance to malaria drug is becoming a major threat to the fight against the disease.

The malaria parasite — plasmodium falciparum — is developing resistance to drugs like artemesinin and chloroquine.

Misuse of malaria drug

Chloroquine was an effective malaria drug that lasted for 50 years. However, it was misused for malaria prevention and ordinary fever, and even mixed with cooking salt, which caused the malaria parasite to become resistant to its active ingredient. It was ultimately banned for use by WHO.

The Kenya government has initiated free indoor residual spraying in malaria-prone areas, which will benefit an estimated four million Kenyans in the western highland areas.

The campaign involves the application of a synthetic pyrethroid with a residual effect on the internal walls and ceilings of houses to kill malaria-transmitting mosquitoes in 680,000 housing units.

ALSO READ: How to drive mosquitoes up the wall

In Uganda, authorities said they would start the phased spraying of Dichloro-diphenyl-trichloroethane (DDT), which they expect will reduce the malaria burden by half in two years.

About 95 per cent of Uganda’s population is exposed to the risk of perennial malaria transmission. The disease kills between 70,000 and 110,000 people annually, and is responsible for 30 to 50 per cent of all outpatient cases in health facilities.

But even as countries adopt all these control measures, malaria remains one of the most adaptive diseases known to man, with the Plasmodium parasite constantly morphing and eluding eradication. Over the centuries, different strategies have had to be adopted in the fight against the disease.

In the 20th century, the use of DDT as an insecticide became popular, and according to the WHO the chemical’s effectiveness in killing mosquitoes was responsible for the eradication of malaria in Taiwan, much of the Caribbean, the Balkans, parts of North Africa, northern Australia, and a large swathe of the South Pacific, as well as dramatically reducing deaths in Sri Lanka and India.

But DDT’s toxicity to the environment led to a public outcry and the chemical was banned in many countries around the world, including much of Africa, where malaria remains endemic.

In recent years, the parasite’s resistance to traditional insecticides based on pyrethrum has increased in many countries, and WHO singles out sub-Saharan Africa as a region of particular concern, with many countries — including much of East Africa — characterised by high levels of malaria transmission and widespread reports of insecticide resistance. The development of new, alternative insecticides is therefore urgent.

Now, larvicides are back on the malaria control agenda in Tanzania, but this time instead of using a synthetic chemical to kill mosquitoes, the Cuban technology uses toxins from bacteria to specifically target mosquito larvae, without affecting the rest of the ecosystem.

“Biolarvicide being a biological larvicide does not harm human beings, wildlife, fish, beneficial predatory insects or the environment,” said Gideon Nasari, managing director of National Development Corporation (NDC), adding that it can also be used in areas where chemical larvicides cannot be used due to resistance and the risk of harming non-target species such as fish.

In contrast, this new technology entails the use of the naturally occurring bacteria. The bacteria eliminate the mosquito larvae through the release of toxins.

When larvae ingest the bacteria, the toxins rapidly attack the gut wall and lesions in the wall lead to paralysis and death of the larvae within 24 hours of ingestion.

Labiofam, the Cuban laboratory in charge of the project has been producing two biolarvicides, Bactivec and Griselesf, since the 1990s.

In 1965, Cuba succeeded in eradicating malaria, largely through the use of chemical and biological insecticides. The country has pioneered research into the use of biological toxins to kill mosquitoes, and Cuba has been particularly keen on partnering with African countries to roll out the technology on a large scale.

West African presence

Cuba already has a presence in West Africa where similar factories are planned for Nigeria, Ghana and Cote d’Ivoire.

Once the Tanzania plant starts its operations the country will export the compound to other countries, which are also in dire need of the eco-friendly malaria products.

Deo Mtasiwa, chief medical officer at Tanzania’s Ministry of Health and Social Welfare, said the Cuban government would oversee the project’s operations while the government of Tanzania could ensure funding is available.

The government said that Tanzania has the third largest population at risk of stable malaria in Africa after Nigeria and the Democratic Republic of Congo (DRC).

Hussein Mwinyi, Minister for Health and Social Welfare, said that financing of malaria control activities is another challenge to the government due to inadequate resources.

Dr Mwinyi said that during the period of 2008-2013, financial requirements for malaria activities are projected at $693 million of which $245 million will be availed to the National Malaria Control Programme (NMCP) from the government, international and national development partners.

“This leaves a gap of $447,805,212 without any identified sources of funding,” said Dr Mwinyi.

Tanzania isn’t the only African country struggling to raise funds to beat the disease. Globally, spending on malaria research and control seems to be slowing.

WHO’s World Malaria Report 2012 shows that after rapid expansion in funding between 2004 and 2009, global funding for malaria prevention and control levelled off between 2010 and 2012, and progress in the delivery of life-saving commodities has slowed.

The report indicates that international funding for malaria appears to have reached a plateau well below the level required to reach the health-related Millennium Development Goals and other internationally-agreed on global malaria targets.

An estimated $5.1 billion is needed every year between 2011 and 2020 to achieve universal access to malaria interventions in the 99 countries with on-going malaria transmission.

While many countries have increased domestic financing for malaria control, the total available global funding remained at $2.3 billion in 2011 — less than half of what is needed.

This means that millions of people living in highly endemic areas continue to lack access to effective malaria prevention, diagnostic testing, and treatment.

Efforts to prevent the emergence and spread of parasite resistance to antimalarial medicines and mosquito resistance to insecticides are also constrained by inadequate funding.

However, Dr Mwinyi said that Tanzania is achieving dramatic improvements in effective malaria case management through implementation of the new treatment policy and the use of artemisinin-based combination therapy (ACT).

ALSO READ: Malaria parasites resistant to ACTs

By Mike Mande and Christine Mungai

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