"We monitored a group of pregnant women with a confirmed diagnosis of Zika and tested their urine over a period of several months at intervals of about a week . In some of these women, the viral load in their urine disappeared and later returned," said principal investigator Maurício Lacerda Nogueira from the FAMERP - Medical School of Sao Jose do Rio Preto, Sao Paulo State .
According to Nogueira, the virus was detected in one patient's urine for as long as seven months . In five women, the test was again positive for Zika virus after their viral load had disappeared in previous tests . In all cases, the virus vanished from the women shortly after they gave birth .
"These results suggest the virus continues replicating during pregnancy, in the fetus or the placenta, which must serve as a reservoir for the pathogen," Nogueira said . "However, viral load in the mother's fluids is intermittent and very low, almost at the detection threshold ."
According to Nogueira, if the result of a molecular test is negative, it should ideally be repeated at least twice at intervals of no less than a week .
"We typically test urine samples because they're easier to obtain and because the blood viral load is lower and disappears faster," he said .
The researchers were unable to establish a correlation between the number of times the virus was detected in the mother and the occurrence of an adverse outcome . "To do so, we will need to perform new studies with a larger number of participants," Nogueira said .
The results are published in the journal Emerging Infectious Diseases . (ANI)