The Zika virus could be a single mutation away from exploding into a worldwide outbreak, new research has found. The infectious virus, responsible for a global health emergency in 2016, needs a single change in its genetic code to create a contagious new variant that could cause devastating birth defects which affected many infants during the previous outbreak.
Results of the research, conducted in mice by researchers from the La Jolla Institute for Immunology in California, were published in the Cell Reports journal.
The World Health Organisation (WHO) too last week warned that the next pandemic could be triggered by insect-borne pathogens, including Zika and dengue.
Emerging viruses, especially those that pose health risks to humans, are monitored and experimented with constantly to identify potential threats and treatments. Experts working with coronaviruses have now proposed theoretical changes to the virus genome that could potentially alter its transmissibility. Other viruses, such as Zika, are no different.
Zika spreads mainly through mosquitoes and has relatively mild symptoms. However, pregnant women infected with the virus then pass it on to their unborn children, resulting in microcephaly that causes infants to have tiny heads and underdeveloped brains. The Zika epidemic that started in Brazil and affected the USAs in 2015 and 2016 caused more than 3,500 cases of infant microcephaly. The World Health Organization said it represented a significant, long-term problem.
The new study has identified a possible evolution of Zika that could enable it to increase transmissibility, even in countries immune from previous outbreaks. The researchers used a mouse model and mosquitoes to simulate the transfer of the virus between the vector and the human hosts and discovered small genetic mutations, which increased the virus’ infectious characteristics. It created a variant capable of evading immunity provided by past infection of dengue or a similar pathogen, suggesting the mutation would enable Zika to return to countries previously affected.
The study’s lead author Professor Sujan Shresta said the Zika variant had evolved to the extent where the cross-protective immunity afforded by previous dengue infection was no longer effective in mice.
If this variant becomes prevalent, the same issues would have to be dealt with in real life, the researcher added.
According to the WHO, dengue fever infects 390 million people in 130 countries annually where it is endemic, while the Zika virus was detected in at least 89 countries during the 2016 outbreak.