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IAEA and Mosquito-borne Diseases


Mosquitoes transmit diseases to over 700 million people annually, but new techniques are being used by the IAEA to reduce their prevalence. (Photo: Insect Pest Control Laboratory (IPCL))

Mosquitoes may be small, but we should not be deceived by their size. From Mozambique to the United States, and from Pakistan to Haiti, these small insects can thrive and multiply in spite of conventional insecticide-based suppression strategies. And wherever we find mosquitoes, we can expect to find the diseases they often carry: malaria, dengue fever and Chikungunya, among others.

All told, mosquitos are estimated to transmit diseases to more than 700 million people annually and some of these diseases can ravage livestock populations too.

Monsoon seasons provide the perfect opportunity for mosquito-borne diseases to spread. Mosquitoes use the hot, rainy seasons to breed in stagnant waters and proliferate into densely-populated regions. During the 2013 monsoon season, more than 12 000 cases of dengue fever were reported in Pakistan. Lacking an established process to collect baseline data on disease epidemiology and vector dynamics, Pakistan requested the IAEA to help address this capacity gap. As part of a Technical Cooperation (TC) project, the Agency has been training Pakistani counterparts in the collection of important data, necessary to develop management strategies for controlling mosquito-borne diseases.

Insects don't respect international boundaries so the IAEA encourages regional cooperation in the fight against insect pests and vector-borne diseases. In 2005-2006, outbreaks of Chikungunya virus occurred in the Indian Ocean region, due in part to human movements between Comoros, Madagascar, Mauritius, La Reunion and Seychelles. Upon the request of these countries, the IAEA is now working to support the development of a standardised vector control policy, through several TC projects. Baseline data is currently being collected in the five countries, with plans to begin suppression trials in pilot sites in 2016.

But gathering information is only the initial part of vector management. The Sterile Insect Technique (SIT) is one of the available methods to suppress insects. It uses radiation exposure to sterilize male mosquitoes. These sterile males are released into the wild, where they compete with wild males to mate with female flies. Released in huge numbers, these sterile flies swamp out the wild males and as the mating results in no offsprings, the insect population gradually dies. SIT works well for a selected group of insects as part of an integrated area-wide approach to pest suppression and eradication. This method has been successful in globally suppressing a variety of insect pest populations, including different species of tsetse flies, moths and fruit flies.

However, SIT techniques have yet to be deployed in a large-scale operation against malarial mosquitoes, in part due to technical challenges that include releasing only male sterile mosquitoes, as well as having efficient trapping systems. In 2011 the IAEA supported a feasibility study at the request of the government of South Africa to determine whether sterilized mosquitos would be effective. In support of this study, the Agency continues to provide expert services and equipment for field work to South Africa under another technical cooperation project.

The presence of disease-carrying mosquitoes not only threatens public health, but in many cases negatively affects tourism, agriculture and travel. Global attempts to control the prevalence of these mosquitoes have also come with hidden costs, such as releasing toxic chemical agents that reduce biodiversity, kill pollinators and natural predators, and leave residues in the environment. Over time, this has resulted in growing public demand for environmentally-friendly and residue-free methods of mosquito control, such as the SIT.

The SIT method fulfills an important part of such public demand, but should not be the only component of an integrated mosquito control strategy. Instead it should be used to complement other measures, such as reduction of mosquito larval breeding areas, promotion of the use of bednets, etc.

In addition, technology transfer, capacity building, and public awareness are all essential factors in the IAEA's insect and pest control strategy. By promoting these methods, the IAEA work with Member States to address health issues arising whenever mosquitoes bite and infect people.

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