A study conducted during the worst Ebola virus epidemic on record identified risk factors for transmission of the disease among household contacts, along with other factors that can be protective, including access to piped drinking water.
For their study, Mary R. Reichler, MD, researcher in the CDC Division of Tuberculosis Elimination, and colleagues enrolled 150 Ebola patients and 845 of their household contacts in and around the capital of Freetown, Sierra Leone, which saw widespread transmission during the West African Ebola epidemic.
Study participants were enrolled from Dec. 15, 2014 — just after the peak of the Freetown epidemic — through April 30, 2015.
Among the 838 household contacts included in the study, 9.9% developed Ebola, including 74 confirmed and nine probable cases, Reichler and colleagues reported.
Less than 1% of the contacts reported touching the body of an index patient after their death — a major risk factor for infection because most Ebola patients die at peak viremia, the researchers noted.
According to their analysis, the risk for household transmission among study participants was 3.5-fold higher when an index patient died.
The household transmission rate was also higher when an index patient had symptoms of Ebola infection but no reported fever, spent more days with wet symptoms — vomiting, diarrhea or bleeding — or was aged younger than 20 years.
According to Reichler and colleagues, avoiding the index patient and having access to piped drinking water — likely because it facilitated better hygiene practices — were associated with lower transmission rates.
They said efforts to minimize contact with Ebola patients by designating one care provider per household could minimize the risk in future outbreaks.
“These could include optimizing community educational messaging about risk factors and protective measures, increasing suspicion of [Ebola virus disease] based on the presence of symptoms with or without fever, and developing approaches to prioritize identifying and managing high-risk contacts.” – by Gerard Gallagher Disclosures: The authors report no relevant financial disclosures.