UNITED NEWS INTERNATIONAL (UNI) – New research suggests a Liberian woman may have infected her husband and two sons with Ebola more than a year after she fell ill.

The findings mark the first potential case of Ebola transmission from a woman to a man after such a prolonged period of time.

Results from the study, published on July 23 in the Lancet Infectious Diseases journal, suggest the virus carried by the husband and two sons was a “continuation” of the 2014 outbreak, which killed more than 11,000 people in West Africa.

The family tested positive after Liberia was declared Ebola-free in 2015 and the study says the findings highlight the need for “continued surveillance.”

One son died from the infection. The other family members, however, have since recovered.

The author of the study said more research needs to be done to “better understand viral persistence and transmission.”