Experts lay groundwork for new global response to vector-borne diseases
On 3-4 August, WHO held its first meeting to lay the foundation of a new Global Vector Control Response. More than 20 leading vector control experts from ministries of health, research institutions, academia and international agencies convened in Geneva.
At least four out of every five people worldwide are at risk of contracting viruses or parasites transmitted by mosquitoes, ticks, fleas and other vectors. Together, vector-borne diseases cause more than 1 million deaths each year. Many who survive are left permanently disabled or disfigured.
“We need to put vector control back on the global public health agenda,” said Dr Dirk Engels, Director of the Department of Control of Neglected Tropical Diseases, in his opening remarks at the meeting. “Over the decades, dengue and chikungunya showed us that an outbreak response is not enough. Now, Zika further emphasises the need for a more fundamental and sustained vector control intervention,” he added.
The Zika emergency
Recently, the explosive spread of Zika has highlighted the dire need for effective global capacity to combat vector-borne diseases, particularly in urban centres. Since 2015 alone, 65 countries have reported cases of this devastating disease that has been linked to severe brain abnormalities in infants.
In her address to the World Health Assembly in May 2016, WHO Director-General Dr Margaret Chan highlighted the poor state of vector control globally. She pointed to the consequences of a “massive policy failure that dropped the ball on mosquito control in the 1970s.” Along with the challenge of Zika, Dr Chan cited the recent resurgence of dengue and the emerging threat of chikungunya, a mosquito-borne disease that causes debilitating joint pain.
At the latest WHO Executive Board meeting, Member States called on the Director-General to develop a Global Vector Control Response in collaboration with affected countries and other relevant stakeholders.
Key challenges and opportunities
Throughout the 2-day meeting, participants noted a range of vector control challenges: a dearth of trained public health entomologists; a lack of domestic funding; weak surveillance systems; poor data management; a greater need for community engagement; a growing threat of insecticide resistance.
But there was a consensus that the opportunities outweigh challenges. Participants pointed, for example, to the existence of disease-specific vector control strategies, capable research institutions, training opportunities and integrated surveillance efforts across disease vectors.
Many participants cited the success of vector control scale-up for malaria, which has played a major role in driving down the global burden of this disease. According to the WHO World Malaria Report, insecticide-treated nets have been by “far the most important intervention” across Africa, accounting for the prevention of an estimated 68% of malaria cases between 2000 and 2015.
Aedes mosquitoes were eliminated in most of the countries of Latin America in the 1960s and 1970s through vector control interventions. In recent years, there has been significant progress in reducing the incidence of visceral leishmaniasis in South-East Asia, mainly through indoor residual spraying.
Dr John Reader, Director of TDR, the Special Programme for Research and Training in Tropical Diseases, noted the critical importance of building vector control capacity at country level. “This is not an initiative that should be directed from Geneva but rather one that strengthens capacity within countries. This involves research, monitoring and evaluation, and all levels of control,” he said.
The way forward
To meet the urgent needs of Member States, the development of the new Global Vector Control Response will be fast-tracked and draw heavily on inputs from Steering Committee members, ministries of health and other partners. The strategic document will be reviewed by the WHO Executive Board in January 2017 for consideration by the World Health Assembly next in May.
“I am hugely optimistic that the complex task we have ahead of us can be completed,” said Dr Pedro Alonso, Director of the Global Malaria Programme, in his closing comments. “The level of engagement and clarity that emerged from just 2 days of discussion is remarkable.”
The meeting was hosted jointly by two Departments within WHO—the Global Malaria Programme and the Department of Control of Neglected and Tropical Diseases —and by the Special Programme for Research and Training in Tropical Diseases, which is hosted by WHO and co-sponsored by UNICEF, UNEP, the World Bank and WHO.
The toll of vector-borne diseases
Collectively, vector-borne diseases place a massive burden on health systems and cause considerable economic and social disruption. Malaria alone claims more than 400 000 lives each year. An estimated 500 000 patients with severe dengue require hospitalization annually. Lymphatic filariasis (elephantiasis), another mosquito-borne disease, has disabled an estimated 40 million people globally.
Chagas disease, transmitted by blood-sucking triatomine bugs, can trigger heart failure and early death in young adults. Visceral leishmaniasis, spread by sand flies, can be fatal if left untreated. And cutaneous leishmaniasis, the most common form of the disease, causes severe skin lesions, leaving life-long scars and serious disability.
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