The burden of dengue is caused by the dengue virus (DENV), a mosquito-borne flavivirus. Image via Sanofi Pasteur

The study published in the New English Journal of Medicine (NEJM) shows that dengue is responsible for around 10% of febrile episodes recorded in children – a startling statistic that highlights the potential impact that is controlling dengue could have.

The research, based on secondary analysis of data generated through clinical trials on the world’s first dengue fever vaccine. Researchers collected data from the control groups in 10 countries from Southeast Asia and Latin America. The findings will feed into ongoing efforts to develop a robust estimate of the true global burden of dengue.

Information was collected on acute febrile illnesses and virologically-confirmed dengue (VCD) in 3,424 healthy children aged between 2 and 16 years in Indonesia, Malaysia, the Philippines, Thailand and Vietnam; and in 6,939 children aged 9 to 18 years in Brazil, Colombia, Honduras, Mexico and Peurto Rico.

VCD incidence ranged from 1.5 to 6.6 per 100 person-years

“The incidence was high which would be expected as dengue is endemic in the countries included in the study,” says Dr. Leon Ochiai, Director of Global Epidemiology at Sanofi Pasteur and corresponding author for the NEJM paper.

“What was quite surprising was the finding that 10% of all children’s fever episodes were caused by dengue. That’s an important public health story and shows that intervening against dengue could reduce fever significantly,” he told Break Dengue.

The paper turned up another eye-catching statistic: around 13% of VCD episodes in the children studied led to hospitalization. Again, this points to the potential for anti-dengue measures to curb pediatric hospitalization.

A female Aedes aegypti mosquito acquiring a blood meal from her human host, who in this instance, was actually the biomedical photographer, James Gathany, from the Centers for Disease Control. Image via Sanofi Pasteur

Standardized approach to managing dengue

The authors say their findings could make a valuable contribution to dengue fever modelling and ongoing efforts to estimate the burden of the disease. The WHO is working to estimate the incidence of dengue around the world, often relying on a broad range of individual studies.

“The data reported here uses standardized laboratory and surveillance methods,” explains Dr. Ochiai. “Instead of comparing apples and oranges we can, for the first time, analyze a comprehensive dataset using a standardized method.”

He says the data is of the highest quality because the standards employed in clinical trials is high.

“In term of quality, this is a huge asset for the WHO and others who are seeking to produce a global estimate of dengue,” Dr. Ochiai says.

The report shows that the epidemiology of dengue varies from year to year and from place to place, highlighting the need for a robust surveillance system to monitor the disease. For disease modelers and forecasters, the data is a rich source of data points on diseases severity across several age groups.

Dr. Ochiai says the findings show that the dengue vaccine, which has been approved in several countries for children aged nine and older, can play a valuable role in reducing the burden of disease. However, he noted that children below this age group are also bearing a significant burden of the disease, highlighting the importance of ongoing efforts to develop a vaccine for younger children.

In response to queries from Break Dengue, the WHO said it’s work on estimating the burden of dengue fever is ongoing. “A final report on the WHO burden project is expected in 2018,” a spokesperson said.

Big, open data

The study sets a potentially powerful precedent in how clinical trial data is used and shared.

While many large – and expensive – clinical trials are conducted to support applications for regulatory approval, taking the analysis one step further can be a tremendous service to the public health community.

“By doing this secondary analysis of the data and sharing the results we are showing our commitment to public health,” Dr. Ochiai says. “When we conduct a study of such high quality – meeting the highest standards of Good Clinical Practice – it is an opportunity to learn more about the diseases by carrying out this kind of secondary analysis.”

He says it would be “a waste” to leave the potential for this sort of analysis untapped. “We shouldn’t just sit on this data. If it can nurture scientific understanding, it needs to be shared.

This approach is in line with big data initiatives in various fields and with the more open approach that many scientists are now embracing.”

It is, he says, a win-win for all who share an interest in public health as it offers a deeper understanding of the disease, how to predict outbreaks and, ultimately, how to reduce the burden.

“Dengue burden is something of a black box so the more data we can generate and share, the better. It is a potential goldmine.”

Watch, ‘The Lingering Effect of Dengue Fever’

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