Another worrisome problem is afflicting many of the same places where Zika is spreading

Tropical infectious diseases have had a grip on the globe long before Zika hit the spotlight.

Take dengue, another mosquito-borne infection that sickens as many as 400 million people a year. It happens in many of the same places where Zika is now spreading.

There’s a commercial vaccine that’s now available for dengue, but it still isn’t available to everyone who needs it.

In December, the company developing it, global pharmaceutical giant Sanofi, got approval to distribute its dengue vaccine in some of the areas that need it the most.

Sanofi is also one of many companies hot on the trail of a possible Zika vaccine. Business Insider spoke with Sanofi’s Chief Scientific Officer, Dr. Gary Nabel, about why the road ahead is so challenging. Nabel said part of the problem is, ironically, that attention on Zika has turned us away from the need to address other tropical diseases like dengue.

Read on to find out more about what’s next for the company — and the world.

The problem with focusing on Zika

With all the attention turning to Zika, similar diseases have taken a back seat. One of the reasons Zika has drawn so much concern is because it has been linked with birth defects in babies whose mothers have had Zika symptoms. It’s also been suggested that there may be a link between Zika and a neurological condition called Guillain-Barré Syndrome.

But that doesn’t mean concern for dengue should go away.

“By no means has dengue diminished,” Nabel said. “It’s just as prevalent as it’s been the past few years.”

“By no means has dengue diminished. It’s just as prevalent as it’s been the past few years.”

That’s especially true when thinking ahead to the 2016 summer Olympics, which are being held in Rio de Janeiro in August.

“I think for example were I going to Brazil and I were an athlete in the Olympic games, I’d have as much cause to worry, maybe more cause to worry [about dengue] at least in the immediate term.” Zika, which typically has low-level symptoms like fever, rash, joint pain, and red eyes if they occur at all, likely aren’t as debilitating as dengue, which can develop into more serious symptoms including severe bleeding and trouble breathing.

“If you get dengue when you’re trying to compete, I doubt you’re going to do much of anything,” he said. That, or even just some of the other microbes hanging out in Brazilian water, “Those are real challenges.”

Another concerning virus

The dengue virus causes flu-like symptoms that can develop into a more serious and deadly infection. There are four types of the virus, or “serotypes,” that cause dengue. Contracting one type of the virus gives you immunity over that specific type for life, but immunity to the three other types is only partial and temporary. It’s endemic in much of Latin America, Southeast Asia and the Pacific Islands, which is why Sanofi chose to launch its vaccine in those areas first.

“When these outbreaks get into full swing, the hospitals essentially become completely flooded,” Nabel said. “The capacity in many of these countries is limited, and it’s quite possible that if you have a car accident or a bike accident, they go into a hospital and they won’t get treated because there’s no place to put them.”

Sanofi officially launched its dengue vaccine in the Philippines on Monday, with plans to produce 100 million of them per year. And researchers are already seeing promising results. So far in trials, the vaccine has reduced 80% of hospitalizations linked with dengue and 93% of severe dengue cases.

Important lessons to fight Zika

Nabel has a long history of developing vaccines. He headed up the Vaccine Research Center at the National Institutes of Health, where he helped to make a West Nile virus vaccine.

What makes Zika interesting to him is that it seems to not have a lot of variety. That’s different from dengue, which has those four serotypes, and viral infections like HIV that have a large amount of diversity. What will be interesting to see as the virus unfolds is how it spreads — with West Nile, the reason the vaccine development never went all the way was because the disease moved quickly from one area to the next.

“As a virologist, I’m not sure I’ve ever met a virus that I don’t like,” he said. “I think you’re much better off if you can avoid infection, and as much as I marvel at the genetic simplicity and the way these viruses can succeed in nature, as one of their potential hosts, I think if you can avoid it altogether I would.”

Nabel said Sanofi, which is working on a Zika vaccine, is in a good spot because of the work they have done on the dengue vaccine. But for Zika, he said, it might be time for pharmaceutical companies to take a different approach to vaccines.

“We have to work with our colleagues in the public health arena, and we have to work with our colleagues in the regulatory area. Because maybe we do have to start thinking a little bit differently.” That’s especially important to the US government’s Zika vaccine timeline, which aims to get a vaccine together in under three years. “We can’t do business as usual.”

NOW WATCH: Why you should never throw away these bags again

Business Insider Emails & Alerts

Site highlights each day to your inbox.

Follow Business Insider Australia on Facebook, Twitter, LinkedIn, and Instagram.