Preliminary results of study on dengue in children will be presented in the Medtrop 2015

Publicação: 3 de June de 2015

The goal is to estimate the infection by the virus and the disease in children up to 2 years of age

In 2007, children responded for 65% of the total severe cases in the Northeast. During the 2008 epidemic, in Rio de Janeiro, 42% of the deaths involved people under 15 years-old

In 2007, children responded for 65% of the total severe cases in the Northeast. During the 2008 epidemic, in Rio de Janeiro, 42% of the deaths involved people under 15 years-old

A current study in Manguinhos Fiocruz, in Rio de Janeiro, which aims to estimate the virus’ incidence in the region, will present the first results during the 51st Congress of the Brazilian Society of Tropical Medicine (BSTM), which will be held in Fortaleza, Ceara State from June 14 o 17. This was said by Dr. Patricia Brasil, PhD in Parasitic Biology. Interviewed by the BSTM, the physician remembers that most of the similar studies are conducted in Southwest Asia.

“We might be able to supply relevant data to support the economic evaluations of the disease load and the cost-effective analysis of alternative control strategies, whether through vaccine or through vector control innovations”, explains.

Dr. Patricia still speaks about the current situation of dengue in Brazil and the perspective for the next years.

Find the full interview below.

BSTM: Is the Brazilian situation regarding dengue fever in the past years concerning?

Dr. Patricia: It is estimated that nearly half the world’s population lives in areas under risk of dengue transmission and that annually 67 to 136 million cases happen in 128 countries.

Dengue is a viral disease transmitted by vectors which are rapidly spreading throughout the world, increasing the incidence 30 times in the past 50 years.

Dengue was reinserted in Brazil in 1986, after an absence of at least 20 years (except for an outbreak in Roraima State in 1981 and casual cases). Since then, the country has become responsible for over 70% of the reported cases in the Americas. During the last decade there was an increase in dengue’s incidence that reflects the broad distribution of the Aedes aegypti in Brazil, and an increase in the number of severe cases, attributed to the recirculation of serotypes DENV 1 and 2.

BSTM: Is it possible that more specific actions towards children could drastically reduce the cases of the disease in the Country?

Dr. Patricia: Since 2006 the disease’s epidemiological pattern is changing in some Brazilian states, increasing child morbidity and lethality. In 2007, in the Northeast, children accounted 65% of the total severe cases. In the 2008 Rio de Janeiro epidemic, 42% of the deaths were among children under 15 years.

Although the disease is caused by several factors, it is thought that the DENV virus circulation in Brazil for more than 20 years is due to the accumulation of immunity among older individuals, diverting the average age of primary and secondary infections towards the younger groups. This pattern, however, is not found in the Center-West and South regions, where the majority of the adult population is still susceptible to the disease, as shown by the current epidemic in the South.

Despite the vector control measures there has been an increase in the dengue incidence rate in the whole world and there are several candidate vaccines in development. The estimate of the incidence is fundamental to evaluate a vaccine effectiveness.

BSTM: In Fiocruz, which are the projects in course regarding dengue among children? How is you work at Fiocruz regarding the studies on the disease?

Dr. Patricia: The majority of the children cohort researches for dengue incidence studies are conducted in Southwest Asia. In the Americas, the Nicaragua cohort by Dr. Eva Harris and, in Brazil, the Recife cohort by Dr. Cynthia Braga (Fiocruz/Recife), were models that inspired me for the Manguinhos cohort in Rio de Janeiro.

The main goal of this study is to estimate the dengue virus (DENV) infection and the disease’s incidence in a cohort of infants during their first two years, through programmed serological inquiries  and an intense surveillance of fevers. We also identify environmental risk factors related to the DENV infection and verify the spacial and temporal distribution of the immature and adult forms of the Aedes aegypti and its relation to dengue cases, capturing the mosquito in households that reported fever cases and surroundings. The project’s entomological component is result of a partnership with Dr. Nildimar Honorio, from the Oswaldo Cruz Institute.

Some preliminary results of the study will be disclosed in the Congress of the Brazilian Society of Tropical Medicine (BSTM) and American Society of Tropical Medicine and Hygiene (ASTMH). We intend to extend for another three years the follow-up of these children in order to investigate the temporal variation of dengue incidence; the cross-immunity between serotypes and severity factors due to multiple infections. Besides this, relevant data to support the economic evaluations of the disease’s load, and the cost-effectiveness analysis of alternative control strategies, whether through vaccine or through vector control may be supplied. The existence of a structured  and specialized team will allow the maintenance of the study, which we have already applied for funding.

The project started in May 2012, thanks to the approval and funding by the research call MCT-CNPq/FIOCRUZ Nº02/2011 – PROEP/Clinical Research and has cooperation of TEIAS from Manguinhos, managed by the National School of Public Health. The multiprofessional team trained in the cohort segment is composed by researchers, pediatricians, nurses, sand-fly experts, laboratory personnel, expert in regulatory subjects, field support and household visit personnel among others.

BSTM: What are the expectations for the disease in Brazil for the next years?

Dr. Patricia: Associating a risk map with detailed longitudinal information about the dengue cohort studies to population surfaces is important to infer the public health problem presented by dengue.

If on the one hand we have dengue dissemination in the Tropics with spacial variations, risk places strongly affected by rainfall, temperature and urbanization level may be predicted; on the other hand, control innovations (transgenic mosquitos and wolbachia) may have promising results.

Similarly, the introduction of the tetravalent vaccine in the market could reduce the severe forms and hospitalizations by dengue, while new vaccines are tested for effectiveness.…