By Susann Roth

This article originally appeared in Asian Development Blog and is republished with permission.

Have you ever had dengue fever? I guess of those of you living in Southeast Asia, 30% will answer ‘yes.’ The same goes for zika in Latin America, and chikungunya in Africa. And with zika now emerging as a threat also in Asia, we can learn from our experience fighting dengue to better face this challenge.

With more than a third of the world's population now living in areas at risk of infection, dengue is a leading cause of illness in the tropics and subtropics. Up to 400 million people are infected worldwide every year, and this number is increasing due to the rapid spread of the aedes aegypti mosquito, which transmits the virus. Aedes aegypti mosquitos travel for example in old car tires, which are traded across the globe. That’s also how the mosquito reached the European continent a couple of years ago.

Aedes aegypti mosquitos also transmit the chikungunya and zika viruses, the latter of which is making big news headlines because of the possible link to microcephaly in newborns of infected mothers. But for your information, zika is not a new disease. It was discovered in 1947 in Uganda, and since then has spread to the rest of the world.

The fact is that with the rapid spread and increase in aedes aegypti mosquitos, your risk of being infected with any of the three diseases increases significantly. Among the reasons for the rapid spread are unplanned urbanization with standing clean water puddles, global temperature increase, travel, trade, and underfunded vector control programs.

So what do you do when you develop fever, joint pain and rashes, and feel pretty miserable? You might belong to the group of privileged patients who have access to laboratory tests that can diagnose dengue, zika and chikungunya. Most people in Asia and the Pacific are not as lucky and don’t have access to such tests, so diagnosis is made on clinical symptoms and medical history. This basically means that many patients are not sure if they really have the diagnosed disease or not. The good news, though, is that dengue, zika and chikungunya all require pretty much the same kind of “symptomatic” treatment and can be managed by out patient care, which is however paid out-of-pocket in most countries.

There is a big problem, though, when a viral infection causes untreatable and irreversible diseases, or affects fetal development. In the case of zika, scientists still have to prove that infected pregnant women are at higher risk of having babies with microcephaly. As the link between other viral infections, like chickenpox, measles or rubella and birth defects, stillbirth and premature delivery has been well established, pregnant women are vaccinated against them in most countries, and must do so before they become pregnant.

Data from Immunization Canada show before the measles, mumps and rubella (MMR) vaccine was introduced in the late 1960s, there were large epidemics of rubella about every seven years.  In one major epidemic in the US, nearly 30,000 babies were infected, more than 8,000 died, and 20,000 were born with defects. This experience informed the implementation of extensive vaccination policies in developed countries.

So why am I saying this? Because we need to learn from the past and invest in prevention, more than relying on response. Yes, the media loves these shocking headlines stories like the ones about zika, but actually they just show how weak the health systems are in many countries, how underfunded health management information systems are, and how little is invested in vector-borne disease research.

One major reason vector borne diseases are underfunded is that in the past many vector-borne diseases mostly affected developing countries, which don’t have the purchasing power to buy new vaccines, so the market is not attractive for pharmaceutical companies.

The spread of aedes aegypti to developed countries will probably lead to new investment commitments for R&D on vector-borne diseases, like the new dengue vaccine recently approved in the Philippines for children above 9 and adults. In the summer of 2014, chikungunya was almost exclusively found in Equatorial Africa, Southeast Asia and China, but by the summer of 2015, the U.S. Centers for Disease Control and Prevention identified human cases all over the Americas. In just a year chikungunya has gone from obscure tropical disease to global phenomenon, infecting new animals, mosquitoes, and human beings on vulnerable continents.

Another reason is that disease spreading across countries is a “public bad” for which no single country feels responsible, as no single country will benefit from its mitigation. Addressing this is a classic “public good,” and public goods in health are severely underfunded. In 2012 these efforts reached $14 billion, or just over 10% of global official development assistance that year ($133 billion).

Finally, we need to do more than just invest in the health sector. Vector-borne disease control requires smart urban planning and management, community mobilization, R&D, regulation of insecticide, and much more.