Summary by: Culzean Kennedy
Emerging infectious diseases can potentially disrupt the circulation of endemic pathogens in a host population through synergistic or competitive interactions. In South America, the emergence of the Zika virus corresponded to reductions in the incidence of endemic dengue virus. The suppressed dengue prevalence and the genetic similarity of the two flaviviruses led a team of researchers, including CEID member Rebecca Borchering, to question the ecological and immunological effects of the co-occurrence of these viruses.
Dengue virus exists as four serotypes within human populations, with each serotype conferring a period of cross-protection against others, following infection. With these immunological effects in mind, researchers sought to characterize the interactions between these genetically similar viruses, which share a vector and an environmental preference. Using available case data from Brazil and Colombia, researchers confirmed the statistical significance of the observed reduction in dengue incidence following the Zika epidemic.
Stochastic compartmental models explored potential immune-mediated interactions between Zika virus and dengue virus through the incorporation of cross-protection or enhancement scenarios. These models predicted a decline in dengue incidence following the Zika epidemic, and a subsequent increase in dengue incidence following the two to four-year trough, within scenarios in which Zika conferred temporary immunity to dengue. Researchers postulate that the genetic similarity of the viruses contributes to cross-protection from Zika as exists between serotypes of dengue.
Issues with case reporting and misdiagnosis, particularly early in the Zika epidemic, may have contributed to difficulty characterizing how Zika incidence affects dengue case-levels. The observed increase in dengue incidence following the period of suppressed transmission, observed in all cross-protection models, suggests that dengue incidence may increase in the coming years. With the reported cases in both Brazil and Colombia as of August 2019 surpassing the reported cases in all of 2017 and 2018, it is speculated that this increase may correspond to the populations’ projected higher susceptibility to dengue following years of lower incidence.
The work was conducted by researchers at UF (Rebecca Borchering, Angkana Huang, Diana Rojas, Leah Katzelnick, Silvio Martinez, Greg King, Stephanie Cinkovich and Derek Cummings), Johns Hopkins University (Luis Mier-y-Teran-Romero, Justin Lessler), and the University of California-San Francisco (Isabel Rodriguez- Barraquer).
Borchering, R.K., Huang, A.T., Mier-y-Teran-Romero, L. et al. Impacts of Zika emergence in Latin America on endemic dengue transmission. Nat Commun 10, 5730 (2019). https://doi.org/10.1038/s41467-019-13628-x