Researchers have warned that the Zika virus is mutating among the infected patients so rapidly that different serotypes of the pathogen could soon appear in the near future, a development that would hinder development of vaccines and efficacy of diagnostic tests.
"Today there's only one Zika and people become immune after being infected once," Edison Luiz Durigon, Professor at the University of Sao Paulo in Brazil, said in a statement.
"But the virus is constantly mutating, and I wouldn't be surprised if we see Zika 2, 3 and 4 emerging before long."
For the study, the team closely monitored asymptomatic patients and collected samples of the patients' blood, saliva and urine, as well as semen in the case of two men, every week to see what was different in the viral genome.
"In one patient, we found compartmentalised strains: the virus present in his semen was different from the virus in his urine. In all cases, the pathogen we found in the final stage of the infection wasn't the same as the virus that entered the patient," Durigon said.
The findings showed that the male patients continued to excrete large amounts of Zika virus in their semen for up to six months. They also were found to have the virus in the saliva for three months.
"Zika continued to replicate in the patient's testicular cells all this time, and using an electron microscope, we could see that the spermatozoa were formed already infected. This means a conception could occur with infected sperm," Durigon said.
Children who get infected by Zika during pregnancy may suffer brain damage but "the problem won't appear until later when they start displaying motor or learning difficulties", Durigon rued.
"We could have a generation of children with all kinds of complications and we won't know how to deal with them."