Sierra Leone yesterday reported its first confirmed Ebola case in 8 days, as the virus flared in a new hot spot in Guinea, tempering the encouragement from a report earlier this week that both countries were making progress toward zero cases, the United Nations Mission for Ebola Emergency Response (UNMEER) reported today.
In other developments, two new genetic studies showed reassuring signs that the outbreak strain isn't gaining changes to make it a bigger threat, and responders reported some of their activities in Liberia.
The World Health Organization (WHO) said in an update today that the three countries have had 26,763 confirmed, probable, or suspected cases and that 11,074 deaths have been reported. The totals include cases reported in Guinea and Sierra Leone as of May 13. No new cases or deaths have been reported in Liberia in several weeks, and the country was declared free of the virus on May 9.
Guinea finds 15 cases
Sierra Leone's new case-patient is from the Moa Wharf area near Freetown where two of the country's most recent cases were reported, in a mother and her 10-year-old daughter. UNMEER said the patient left the area and was missing for about 2 weeks. It said surveillance teams took the patient to a treatment center and are looking for people who may have had contact with the individual.
Guinea reported 15 new cases in the first 3 days of this week, including 9 from an outbreak of in Dubreka district, UNMEER said. All of the patients are from Tanene subdistrict. None were registered contacts, but investigations after the illnesses were detected found links to other cases. Several contacts of a confirmed case in Boke had fled to Tanene using public transportation while showing symptoms of the disease, UNMEER said.
Media reports suggested that the number of fresh cases in Guinea is even higher. A government official told Reuters that there are 27 patients in treatment centers, including 18 confirmed Ebola cases. The official said people contracted the disease at funeral ceremonies.
The WHO warned in its weekly epidemiologic report 2 days ago that cases in Guinea could increase. It said one of the cases last week was in Dubreka and that preliminary reports suggested there were three related cases. It added that Guinea's response indicators were still shaky, raising concerns that cases could surge again, as they have several times in the course of the outbreak.
Global health officials predicted earlier this spring that the outbreak would have a long and bumpy tail. Responders have faced increasing urgency to shrink the number of cases and limit them to urban areas ahead of the rainy season, which will slow the response and make it difficult for medical teams to reach remote areas.
Genetic studies reassuring
Genetic studies on Ebola viruses published over the past few days have found no worrisome signs, despite preliminary findings last fall that raised some concerns that the outbreak strain was changing faster than expected.
Researchers from the University of Florida and their colleagues from Italy looked at samples from humans and great apes collected during epidemics from 1976 to 2014. In Nature Scientific Reports yesterday they wrote that most genetic changes seem to be lost between epidemics, and they found little evidence that the virus is evolving to become more powerful or transmissible.
Taj Azarian, PhD, lead author with the department of epidemiology at the University of Florida, said in a university press release that concerns about airborne Ebola may persist, but the likelihood of its becoming an airborne infection is very low.
Meanwhile, Chinese scientists with links to a lab in Sierra Leone wrote in a May 14 Nature letter that the virus became more diverse between July and November, with the emergence of multiple lineages. However, they said the rate was similar to viruses in other Ebola outbreaks. They based their analysis on 175 full-genome samples from five hard-hit districts in Sierra Leone from September through November.
They added that the sharp increase in diversity warrants extensive surveillance to better understand evolution and transmission dynamics.
Lessons from Liberia
Outbreak responders from the US Centers for Disease Control and Prevention (CDC) and their international partners today shared more lessons they learned from battling the disease in Liberia, now free of the disease. They detailed their experiences in two reports in today's Morbidity and Mortality Weekly Report (MMWR), one on Liberia's last cluster and the other on a ring approach to infection prevention at non-Ebola health facilities early this year.
In the first report, they described how tried-and-true strategies were successful in stamping out the last known cluster. The index patient was a 50-year-old woman who got sick in late December in the Monrovia area. Over the next 7 weeks, 21 additional cases were linked to contact with the woman, and there were three generations of transmission.
Tactics for stamping out transmission included early detection of new cases, managing contacts in appropriate settings, effective triage in healthcare settings, and rapid isolation of asymptomatic contacts, the team wrote.
In the ring strategy report, responders described a program of intensified infection control practices at health facilities in areas of active Ebola transmission. Liberian health officials and their partners took the step in January and February in response to what turned out to be the country's last cluster, which was in and around Monrovia.
In the 22-person cluster, 8 sought care at non-Ebola health facilities. The team noted that the ring efforts appeared to be associated with an increase in detection and isolation of suspected and probable Ebola patients, and only one of 166 exposed health workers who were contacts of the cluster patients got sick with the virus.
The authors concluded that the ring infection prevention strategy might be useful for limiting the spread of Ebola in other settings.
May 15 UNMEER report
May 15 WHO update
May 15 Reuters story
May 14 Scientific Reports abstract
May 14 University of Florida press release
May 13 Nature abstract
May 15 MMWR report on last Liberian cluster
May 15 MMWR report on ring Ebola prevention in Liberia