A team of researchers affiliated with several institutions in the U.S. and Canada has found that the Zika virus remains in some macaques’ organs and fluids, even after the immune system has removed it from the blood stream. In their paper published in the journal Nature Medicine, the researchers outline their study, detail their results and offer some thoughts on what they think should be done to learn more about the infection in people.
The Zika virus has been in the news a lot over the past year after it was discovered to be causing severe birth defects in children born to infected women—mostly in South America. News that it was spreading led to research efforts to find a vaccine or a means to treat patients before it could cause more harm. In this new effort, the researchers sought to better understand the infection process in a close human substitute— macaques. They infected several subjects just under the skin with two strains of the virus, as would occur with a mosquito bite, and then watched how it traveled though the bodies of the monkeys while also tracking the immune response.
The researchers found that the virus made its way almost immediately to the lymph nodes but within five days the immune system had cleared the virus from the bloodstream. But they also found that the virus was still present in saliva, testes, prostate and semen in males and in the uterus in females for up to three weeks before it was finally overcome by the immune system. They also found that at some point, the virus had made its way to the cerebrospinal fluid around the brain, and spinal fluid, and that it had infected neurons in the cerebellum.
It is not clear at this time if the virus moves through the human body in the same way as it does with the macaques, but the researchers suggest that longer-term testing of infected humans be done to find out. If it is the case, it could mean there is a longer infectious period for such patients. They note that more research needs to be conducted to find out if the virus causes damage to the brain or the nervous system in adults, and if so, in what ways.