How small bites take a big chunk out of healthy economies and households

Small bite - big threat." The theme of World Health Day is a timely reminder of the enormous harm caused by tiny creatures such as mosquitoes, ticks, fleas, mites, sandflies and freshwater snails.

These animals, called "vectors", help spread a range of parasitic, viral and bacterial diseases that affect people of all ages and across all socio-economic backgrounds.

Certain diseases - such as malaria and dengue, both transmitted by mosquitoes - are well-publicised. Others are relatively neglected even though they cause so much damage.

Vector-borne diseases are reported in the World Health Organisation's Southeast Asia and Western Pacific regions and across the world. Some are locally transmitted. Others are imported from affected countries. Many, especially dengue, are linked to issues such as urbanisation, the rapid transportation of people and goods in a global economy, or even environmental change. It is truly a complex picture.

All vector-borne diseases take a human toll. But they also have significant development impact.

Take dengue, for example. The Asia-Pacific region reports nearly 75 per cent of the estimated global dengue burden of more than 100 million infections every year. While dengue mortality is not high, the costs of this debilitating disease include the productivity lost when people are ill as well as the financial burden of accessing health services for severe cases. These costs have large and growing negative impacts on economies and households. Diseases such as dengue can also affect revenue from tourism and foreign direct investment.