Study on the persistence of Zika virus in body fluids

April 2017

Zika virus is the first virus known to be transmitted to humans through the bite of an infected mosquito and through sex with an infected person.

Over the course of 2016, WHO along with the global research community quickly built evidence that Zika virus transmission through sex was not only possible, but more common than previously assumed.

But many questions still remain unanswered: How long does the virus stay in the body? Could the virus remain dormant in a person and reappear at a later stage? WHO is coordinating a research study in Brazil, called ZikaBra, to address these questions. The answers will help WHO sharpen its recommendations on how best to prevent Zika virus infection.

WHO/E. Kara

The research study will be carried out in three cities in Brazil: Rio de Janeiro (pictured above), Manaus and Recife. These cities meet the necessary characteristics to be part of the study; that is, areas with densely populated communities and where Zika virus activity was present in 2016. In addition, they also have proactive community health networks and laboratories able to perform complex tests on body fluids.


WHO/E. Kara

Adults who present with Zika virus symptoms at municipal health centres, emergency units and local neighbourhood clinics, like the one pictured above, will be asked to participate in the study. Their household contacts and their sexual partners also will be asked whether they would like to participate, regardless of presenting symptoms. Around 1300 volunteers in total are expected to be recruited in the 3 cities.


WHO/E. Kara

The research team met at Fundação de Medicina Tropical Doutor Heitor Vieira Dourado, a centre dedicated exclusively to the diagnosis and treatment of tropical diseases, in Manaus before the launch of the study. The team discussed how nurses in the study will provide counselling and education to participants. Nurses will be trained to discuss intimate and sensitive issues with participants who will learn how Zika virus is transmitted and how to prevent infection and unwanted pregnancies.


WHO/E. Kara

Men and women with Zika signs or symptoms will be referred to the study nurse, who will ask whether they would like to participate in the study. They will be informed that they are: free to choose whether or not to participate in the research; can withdraw from the study at any time; and need to express their consent in writing (“informed consent”). They also will be asked whether the collected body fluids can be used in future research projects. This standard research procedure is helpful to conduct additional studies long after the initial study has been completed. All measures will be established and agreed on by national and WHO ethical committees to ensure that the interests of study participants are protected.


WHO/E. Kara

Zika virus has been found in body fluids such as blood, urine, semen, brain and spinal fluids, saliva, amniotic fluid/women’s waters and breast milk. Research has found that Zika virus can persist longer in urine and semen than in blood. A range of body fluids will be collected from participants over a period of 12 months. The samples will be tested for the presence of Zika virus and for the participants’ immune responses at different points in time.


WHO/E. Kara

The ZikaBra study is led by WHO in collaboration with the Brazilian Ministry of Health, Fiocruz (pictured above) and the Walter Reed U.S. Army Institute of Research. All of the partners make unique contributions. WHO, for example, has developed a generic protocol for measuring the persistence of Zika virus in body fluids so that results from research around the world can be compared, providing a global picture of Zika virus. The ZikaBra study was developed using this protocol.

The study results are expected by mid-2018.