The main hypothesis for the new cases is "recrudescence," which means a surge in the replication of a virus from a dormant state, possibly in connection with a weakened immune system.
A Liberian woman who survived the Ebola virus disease over a year ago may have become infectious again, passing the disease on to her family. Her son died on Nov. 24.
It was originally thought that 15-year-old Nathan Gbotoe was the originator of the outbreak in Liberia that occurred months after the country was declared Ebola-free. Now attention has shifted to the boy’s family, particularly his 33-year-old mother, Ophelia.
It is thought that perhaps the dormant virus carried by Ophelia became active due to a weakened immune system. She became infected more than a year ago, catching the virus from her brother, who died in July 2014. Ebola can become dormant and remain hidden in body areas such as testicles and eyes. Rare cases of the virus re-emerging have been reported. Ophelia is pregnant, and antibodies that fight the disease tend to drop as a woman nears her delivery date.
It is unknown how the woman might have infected her family. The virus is found in bodily fluids.
Officials in neighboring Sierra Leone have reported other deaths which may be due to relapses of Ebola. Doctors are urging closer monitoring of survivors, particularly women, to prevent future outbreaks. So far survivor screening has focused on men, who have submitted semen samples to determine whether any traces of the virus linger.
According to Jonathan Heeney, Cambridge University professor of comparative pathology, survivors can be divided into two categories, carrier or cleared. The categorization would be partially based on factors that weaken the immune system and cause to virus to once again replicate to high levels, including pregnancy or HIV.
Liberian officials have ruled out the possibility that the virus was introduced from an animal, or from another country. Tolbert Nyenswah, the head of Liberia’s Ebola response, says the new cases are of the same strain of virus that has been known there before.