‘Dengue Mata’ - A Look at Brazilian Disease Control during and past the World Cup

‘Dengue Mata’ - A Look at Brazilian Disease Control during and past the World Cup

After Sunday, the crowds will disperse in Rio de Janeiro and the World Cup of 2014 will conclude - a spectacle of athleticism and international competition, but an event that has also served as an international forum on healthcare in Brazil. Epidemiology has been a chief concern of authorities when accounting for the expected 600,000 tourists in Brazil for the tournament. Brazil has the world’s greatest incidence of dengue (~1 million cases a year), a potentially fatal, viral disease with flu-like symptoms transmitted by mosquitoes. The dengue season has been prolonged this year in Brazil due to a heat wave lasting into the winter season. Estimates of dengue cases among tourists during the World Cup have ranged anywhere from 33 to over 370. Significant International transmission of the disease is an unlikely outcome, though the threat of dengue endures in Brazil past its current spotlight. Behind the disease control initiatives discussed in this article, dengue diagnostics play a significant role in public health and disease surveillance in Brazil.

Dengue is controlled largely through preventative measures; there is no vaccine or targeted therapeutic available. Several innovative options are available to Brazil for the mitigation of dengue:

  • One clinician-developed smartphone app allows users to pin maps where dengue cases have been identified so that immediate preventative and eradication measures can be taken (pesticide application, elimination of standing water and other mosquito breeding sites)
  • Release of genetically modified male mosquitoes into natural populations to introduce lethal genes that result in premature death of offspring
  • Gates Foundation-backed researchers at Monash University are seeking to introduce Wolbachia bacteria into mosquitoes that would inhibit the spread of dengue to humans
  • ‘Dengue Mata’ and similar public outreach campaigns by Brazilian authorities seek to recruit residents for community groups to clean up neighborhoods and eliminate mosquito breeding sites

The above technologies are still in development are have yet to be widely and consistently implemented, providing a consistent role for diagnostics in dengue control and surveillance in Brazil.

Immunoassays for the diagnosis of dengue (detecting anti-dengue antibodies) are also cross-reactive or display positive results with flaviviruses (yellow fever [endemic], West Nile, St. Louis encephalitis, Japanese encephalitis). IgM antibody capture assays, including microtiter enzyme-linked immunoabsorbent assays (MAC-ELISA), are most common for the initial diagnosis of dengue during acute and late acute stages (5+ days) when IgM antibodies against dengue are most prevalent. The diagnosis of dengue past its acute stage is more readily accomplished with an anti-dengue IgG antibody immunoassay. In the case of secondary and repeat dengue infection, IgG immunoassays can be used during the acute phase due to faster developing immune response.

Immunoassays are also available for the non-structural protein 1 (NS1) dengue antigen detectable from the onset of symptoms through the acute disease phase. Molecular test kits for dengue are not commercially available (research-use only RT-PCR kits exist as does an FDA-approved, CDC-developed kit available for distribution) but offer great promise for early clinical detection with excellent sensitivity and specificity.

For the latest full year (2013), Brazil reported approximately 1.5 million cases of dengue and the publicly funded health care system Sistema Único de Saúde (SUS) received claims for approximately 720,000 immunoassays (550,000 IgM and 170,000 IgG) representing approximately $20 million in testing value. Fewer cases of dengue have been reported in Brazil so far in 2014, though several notable outbreaks have occurred including some near World Cup sites. National immunoassay testing volumes for dengue under SUS have increased from roughly 540,000 in 2010 and 2011 to 650,000 in 2012 and 720,000 in 2013. Under variable year-to-year national incidence, testing intensity appears to be rising in Brazil, at least under SUS.

The entire infectious disease immunoassay market in Brazil has similarly grown in recent years and Kalorama Information expects it to grow annually by 7% through 2017. The tall task of tropical disease mitigation in the country coupled with gradual expansion of health service accessibility is expected to sustain and grow Brazilian test volumes.

Kalorama Information offers excellent resources regarding IVD markets in Brazil as well as the global infectious disease test market.