Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tanzania study reopens debate on targeting mosquito larvae to control malaria

01.04.2009
Targeting mosquito larval populations may be an effective intervention to help control malaria in urban situations, a study published today suggests. The research, conducted in Dar es Salaam, the largest city in Tanzania, has re-opened the debate on whether malaria can be controlled with larvicides, insecticides which kill mosquitoes in their water-borne larval stages of development.

Malaria is one of the world's deadliest diseases, killing over one million people each year, mainly young children in Africa. It is caused by the malaria parasite, which is transmitted through the bites of mosquitoes.

Governments and NGOs worldwide are making a concerted effort to tackle malaria and a number of interventions exist to control its spread, including the use of insecticide-treated bed nets (ITNs), sprays and repellents. However, most interventions target adult mosquitoes, which can carry the parasite. Larvicides were used in the early twentieth century, but the successful introduction of the pesticide DDT to kill adult mosquitoes meant that larvicides fell out of favour.

Nowadays, larvicides are available which kill only mosquito larvae and are biological in nature, environmentally friendly and are safe to apply even to drinking water. These products have been used for decades in mosquito programmes all across the northern hemisphere but the major question mark which had limited their use for malaria prevention was whether their implementation could be sustainable and cost-effective in the poorest countries of Africa.

Tanzania has emphasised the widespread use of ITNs as its highest priority for controlling malaria, but recent observations suggest that in urban areas such as Dar es Salaam, mosquitoes tend to bite outdoors, making the nets slightly less effective as a control strategy than in rural areas.

In 2003, the Dar es Salaam City Council established a new Urban Malaria Control Programme which spent 3 years developing new, sustainable and affordable systems for applying microbial larvicides by mobilizing community-based teams of operators. In a pilot study to evaluate this approach, three wards of the city, covering an area of 17km2 and 128,000 inhabitants, were treated with the microbial larvicide Bacillus thuringiensis var. israelensis (Bti) over a one year period.

In a study published today in the open access journal PLoS One, an implementation team of almost 300 community-based staff led by Ms Khadija Kannady from the Dar es Salaam City Council, and a supporting team of researchers led by Wellcome Trust Research Career Development Fellow Dr Gerry Killeen, have shown that the use of larvicides to complement existing interventions appears to have had a dramatic effect in reducing malaria risk in the pilot areas.

"Malaria control programmes have traditionally focused on rural areas, where the disease is more prevalent," says Dr Killeen, from the Liverpool School of Tropical Medicine, who is based at the Ifakara Health Institute in Tanzania. "However, it's becoming clear that malaria also poses a problem in towns or cities, where we expect that over half the African population will live by 2030. In fact, it is likely that malaria is easier to control and even eliminate in these areas."

Dr Killeen and his colleagues from the Ifakara Health Institute in Tanzania, as well as Durham University, Harvard University, Swiss Tropical Institute and the Liverpool School of Tropical Medicine, found that the pilot programme achieved a 72% reduction in the prevalence of malaria infection among young children in Dar es Salaam. This dramatic reduction also proved to be highly cost-effective: an annual cost of less than US$1 per person protected, compared to US$2 per year of use of an ITN, typically by more than one person.

The study supports ongoing research in the densely populated rural highlands of western Kenya, which have also shown the effectiveness of using larvicide application as a malaria prevention measure. However, the researchers stress that larvicide is not intended to replace ITNs and other interventions, but rather should be a complementary approach.

"There is no evidence that using larvicide is a substitute for the current front-line interventions," says lead author Dr Yvonne Geissbühler from the Swiss Tropical Institute, Switzerland. "ITNs and indoor residual spraying are, and should remain, the highest priority, but using larvicide may offer a supplementary means to control or even eliminate malaria."

The programme in Dar es Salaam has already been extended to protect over 600,000 people, with lessons learned during this pilot study being translated into major improvements in the delivery system to reduce costs and improve performance. Furthermore, expansion to eventually cover the entire city is being considered at the stakeholders meeting of the US President's Malaria Initiative held in Tanzania this week and the National Malaria Control Programme has now set itself the target of setting up such programmes in five cities by 2013.

The study was supported by the Bill & Melinda Gates Foundation, Valent Biosciences Corporation, Research Triangle International, the US President's Malaria Initiative and the Wellcome Trust.

Craig Brierley | EurekAlert!
Further information:
http://www.wellcome.ac.uk

More articles from Studies and Analyses:

nachricht Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung

nachricht Scientists reveal source of human heartbeat in 3-D
07.08.2017 | University of Manchester

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>