Zika has a lot in common with dengue, in that both viruses belong to the Flaviviridae family and they are both transmitted primarily via the Aedes aegypti mosquito. This means that both spread in similar ways, and records of the proliferation of dengue, or other similar viruses, can be used to predict the spread of Zika. As a result, the team’s mathematical models suggest that the most likely scenario is that herd immunity will kick in by the end of next year, and Zika’s spread will rapidly be culled.
Counterintuitively, the team suggest that any efforts to slow viral transmission, like targeting the mosquitos themselves, may not be a good idea. “Slowing transmission between people means the population will take longer to reach the level of herd immunity needed for transmission to stop,” Ferguson added.
This study also suggests that any vaccines that are currently being trialed will not be able to be applied before the drop off begins to occur. In any case, whether you’re designing a vaccine or estimating transmission rates for the Zika virus, there are plenty of complications that may throw a curveball into proceedings, particularly when it comes to the effect the dengue virus may have on those at risk of Zika infection.
Previous research has revealed that if a person has been previously infected by the dengue virus, a subsequent Zika viral infection will either occur 12 times faster than it otherwise would, or it may not occur at all, depending on the antibodies produced by the host. At present, this effect is incredibly difficult to model.
“There are currently more questions surrounding Zika than answers,” Ferguson concluded. “Only through a coordinated global research effort will we find the answers we desperately need.”
Efforts to stop the spread of mosquitos carrying Zika may actually backfire, according to this study. Jung Rattanasiri/Shutterstock