News / Health

Vaccines in Development to Protect Against Dengue Fever

A boy tries to outrun a man fumigating for mosquitoes in an effort to combat dengue fever, on the streets of Lahore, Pakistan, September 20, 2011.
A boy tries to outrun a man fumigating for mosquitoes in an effort to combat dengue fever, on the streets of Lahore, Pakistan, September 20, 2011.
TEXT SIZE - +
Jessica Berman

The World Health Organization estimates that 2.5 billion people - more two-fifths of the world's population - are at risk of infection with Dengue fever, a mosquito-borne illness that in its worst form can cause death. Until now, efforts to develop a vaccine against the disease have been unsuccessful. Researchers say a couple of experimental vaccines are showing promise.

Since Dengue fever was first identified a half century ago, the incidence of the disease has grown dramatically. The World Health Organization says Dengue fever today is endemic in more than 100 countries, and more than 50 million people are infected every year.  

Scott Halstead, senior advisor to the Dengue Vaccine Initiative, an international consortium of medical research groups, said that fluid treatments for the disease have reduced mortality from the most severe form of the illness. But Halstead added that the rainy season in many parts of the tropics and subtropics - when Dengue-carrying mosquitoes are breeding and biting - is still a time of special anxiety because there is no specific medication or cure for Dengue fever:  

“While the mortality rate, in reality, is relatively low because of the availability of good hospital treatment, this is almost unlike any other major infectious disease,” said Halstead.

In its worst form, Dengue fever, also known as "breakbone fever," can cause severe internal bleeding, circulatory failure, shock, coma and death.

There are four related, but distinct, types of the Dengue virus that are transmitted by the bite of the Aedes aegypti mosquito. The difficulty in developing a vaccine, according to Halstead, is that a person may develop immune system antibodies against one type of virus, but would have no immunity against the other types.  

Halstead said that sets the stage for more serious infection later on.

“The antibodies that are left over from the first infection interact with the second type of the virus, and what we say is it “enhances” the infection; it makes it more severe the next time you’re infected with a different type of virus,” said Halstead.

Experts say it’s usually a second infection with a different Dengue virus that leads to the most severe and sometimes fatal form of the disease - Dengue hemorrhagic fever.

Two promising vaccine candidates now are in the works to protect against all types of Dengue virus. Both vaccines contain the four types of live but weakened viruses, designed to stimulate the body's production of neutralizing antibodies against all Dengue types.

French drug maker Sanofi-Pasteur has reportedly invested nearly $1 billion to develop a vaccine that is proving highly effective in phase-three human clinical trials in Thailand, the last step before regulatory approval. A second vaccine, being developed by U.S. drug maker Inviragen, also has proved to be safe and effective in phase-one human trials.

Dan Stinchcomb, Inviragen’s chief executive officer, said that despite the millions of dollars it has spent so far to develop the Dengue vaccine, the company hopes to keep it affordable.

“Our intention is to try to produce the vaccine at low cost so that we can provide it with help of funding to the poorest in need of the vaccine,” said Stinchcomb.

Progress on both Dengue vaccine candidates was reported at the recent meeting of the American Society for Tropical Medicine and Hygiene in Philadelphia, Pennsylvania.

You May Like

Multimedia Anti-Keystone XL Protests Continue

Demonstrators are worried about pipeline's effect on climate change, their traditional way of life, health and safety More

Thailand's Political Power Struggle Continues

Court gave Prime Minister Yingluck Shinawatra until May 2 to prepare her defense over abuse of power charges but uncertainty remains over election timing More

Malaysia Plane Search Tests Limits of Ocean Mapping Technology

Expert tells VOA existing equipment’s maximum operating depth is around 6 kilometers as operation continues on ocean bed for any trace of MH370 More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Pet Kangaroo Helps Spread Environmental Messagei
X
Penelope Poulou
April 22, 2014 5:53 PM
Children’s author Julia Heckathorn travels the world to learn about different ecosystems and endangered animals. She pours her knowledge into children’s books, hoping the next generation will right the environmental wrongs of our times. As in many children's books, the main character in Heckathorn's stories is an animal. Unlike those other characters, though, this one is real - a kangaroo, that lives in the author’s backyard. VOA’s Penelope Poulou has more.
Video

Video Pet Kangaroo Helps Spread Environmental Message

Children’s author Julia Heckathorn travels the world to learn about different ecosystems and endangered animals. She pours her knowledge into children’s books, hoping the next generation will right the environmental wrongs of our times. As in many children's books, the main character in Heckathorn's stories is an animal. Unlike those other characters, though, this one is real - a kangaroo, that lives in the author’s backyard. VOA’s Penelope Poulou has more.
Video

Video Pro-Russian Separatists Plan 'Federalization Referendum' in Eastern Ukraine

Pro-Russian separatists in eastern Ukraine say they plan to move forward next month with a referendum vote for greater autonomy, despite the Geneva agreement reached with Russia, the U.S. and Ukraine to end the political conflict. VOA's Brian Padden reports from the city of Donetsk in Eastern Ukraine.
Video

Video Pope Francis Hopes Dual Canonizations Will Reconcile Church

On April 27, two popes - John the XXIII and John Paul II - will be made saints in a ceremony at St. Peter’s Square. VOA religion correspondent Jerome Socolovsky says the dual canonization is part of the current pope’s program to reconcile liberals and conservatives in the Roman Catholic Church.
Video

Video In Capturing Nature's Majesty, Film Makes Case for Its Survival

French filmmaker Luc Jacquet won worldwide acclaim for his 2005 Academy Award-winning documentary "March of the Penguins". Now Jacquet is back with a new film that takes movie-goers deep into the heart of a tropical rainforest - not only to celebrate its grandeur, but to make the case for its survival. VOA's Rosanne Skirble reports.
Video

Video Boston Marathon Bittersweet for Many Runners

Monday's running of the Boston Marathon was bittersweet for many of the 36,000 participants as they finished the run that was interrupted by a double bombing last year. Many gathered along the route paid respect to the four people killed as a result of two bombings near the finish line. VOA's Carolyn Presutti returned to Boston this year to follow two runners, forever changed because of the crimes.
Video

Video International Students Learn Film Production in World's Movie Capital

Hollywood - which is part of Los Angeles - is the movie capital of the world, and many aspiring filmmakers go there in hopes of breaking into the movie business. Mike O'Sullivan reports that regional universities are also a magnet for students who hope to become producers or directors.
Video

Video Pacific Rim Trade Deal Proves Elusive

With the U.S.-led war in Iraq ended and American military involvement in Afghanistan winding down, President Barack Obama has sought to pivot the country's foreign policy focus towards Asia. One aspect of that pivot is the negotiation of a free-trade agreement among 12 Pacific Rim nations. But as Obama leaves this week on a trip to four Asian countries he has found it very difficult to complete the trade pact. VOA's Ken Bredemeier has more from Washington.
Video

Video Autistic Adults Face Housing, Job Challenges

Many parents of children with disabilities fear for the future of their adult child. It can be difficult to find services to help adults with disabilities - physical, mental or emotional - find work or live on their own. The mother of an autistic boy set up a foundation to advocate for the estimated 1.2 million American adults with autism, a developmental disorder that causes communication difficulties and often social difficulties. VOA's Faiza Elmasry reports.
AppleAndroid