The current zika epidemic in the Americas and a few other countries is likely to end in another three years, according to a new study published in Science journal.
The study said that the epidemic cannot be contained with existing control measures but added that the next large-scale epidemic is unlikely to surface for at least another decade, although there is a possibility of smaller outbreaks during this time.
“This study uses all available data to provide an understanding of how the disease will unfold—and allows us to gauge the threat in the imminent future. Our analysis suggests that zika spread is not containable, but that the epidemic will burn itself out within 2-3 years," said Neil Ferguson, lead author of the research, from the School of Public Health at Imperial College, London.
The scientists at Imperial College used existing data for zika transmission across Latin America as well as data on similar viruses such as dengue, and built a mathematical model to characterize the current epidemic and future transmission.
The World Health Organization (WHO) declared a ‘Public Health Emergency of International Concern’ due to the outbreak of zika and related cases of microcephaly and neurological disorders among newborns. Since 2015, 48 countries have reported their first zika outbreaks, according to WHO. There are more than 1,700 cases of microcephaly, which is a condition that causes newborn babies to have abnormally small heads and incomplete brain development.
“The current explosive epidemic will burn itself out due to a phenomenon called herd immunity. Because the virus is unable to infect the same person twice—thanks to the immune system generating antibodies to kill it—the epidemic reaches a stage where there are too few people left to infect for transmission to be sustained," Ferguson explained in a press release.
The model predicts that large-scale transmission will not take place for at least another 10 years, by when there will be a new generation which has not been exposed to the zika virus.
Although the zika virus is spread by the Aedes aegypti mosquito, the scientists said large-scale government programmes to target the mosquitoes may not have much impact. “The virus is very similar to the dengue virus, and transmitted by the same mosquito. But previous experience with dengue has shown controlling spread to be incredibly difficult," said Ferguson.
“Also, efforts to contain the epidemic would have needed to have been implemented much earlier in the current zika epidemic to have a major effect. By the time we realized the scale of the problem, it was too late," he added.