BlessWorld Foundation International

Affecting the World Through Health
A Global Health Initiative

Vector-borne Diseases



The effects of vector borne diseases have been strongly felt throughout the course of human history even though the relationship between vectors and diseases was not established until 1890s. Ever since then, they have been recognized as important global disease burden accounting for about 17% of all infectious diseases. Vector borne diseases are diseases that are transmitted by vectors- insects that harbour infectious agents. Vectors can harbour virtually any infectious agent including bacteria, viruses, protozoa and can transmit more than one infectious agent e.g. mosquito which transmits malaria and filariasis. Vectors also tend to be distributed based on the environmental parameters leading to unequal disease distribution, for e.g. mosquitoes in tropics and sand flies in Asia. However, the drastic effects of climate change coupled with advances in human transportation and industrialisation is blurring this line.

Despite being public health threats, vectors are also part of our ecosystem and help to create balance. Environmental parameters like climate change are perhaps the most significant causes of imbalance which accounts for the increased incidence of diseases. Also, pollution can serve as a breeding ground as seen in mosquitos or housefly in improperly disposed sewage. This reason coupled with weak public health response is why poorer communities, especially in Africa, tend to have more vector burden compared to the developed world. Another factor is seen in the late 20th century when the war over vectors was thought to be almost over. A shocking incidence followed- mosquitoes suddenly developed resistance over insecticides like DDT which was effectively used to control them. This is even worsened by the infectious agents that can also become resistant to drugs, and can even mutate to more pathogenic strains as seen in influenza. There seems to be really no way around these mechanisms of microbial adaptation, mutation and evolution.

Whether it’s the vectors or the organisms themselves, it takes time for these survival mechanisms to develop and it is within this time lag that public health responses and efforts can be useful to control the spread of these diseases. This is illustrated by the significant reduction of these diseases during the widespread public health campaigns in early 1900s. Generally vector borne diseases are controlled by educating the public on the importance of the environment on health; reducing pollution, better housing and sanitation could reduce disease spread. In addition, removing the source of these organisms like stagnant water and providing materials like nets to prevent their contact with people would go a long way in reducing spread. There should be increased provision and availability of vaccines for better coverage against infection as well as research into newer vaccines to include newer types of organisms. Funding of public health services in remote areas with higher prevalence is essential to educate people on the lifecycle of vectors and where we can intervene to limit their spread. Research into more efficient ways of vector control has led to novel approaches involving biological control like use nanotechnology such as nanoparticles and genetic engineering as well as the Oxitec friendly mosquitoes.

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