Ebola: Liberia Cases Declining, Remote Clusters Appearing

Larry Hand

November 18, 2014

The weekly number of new cases of Ebola virus disease (EBV) appears to be declining in Liberia, although health officials warn that geographical spread of the disease and remote outbreaks still call for increased intervention.

The current Ebola epidemic is the largest and longest Ebola epidemic in history and the first in West Africa, including Liberia, Guinea, and Sierra Leone. Liberia has reported the largest number of cases and deaths.

The Liberia situation is detailed in three early-release articles published online November 14 in the Morbidity and Mortality Weekly Report.

“The recent decrease in cases suggested by these reports shows how important it is to continue to intensify our Ebola response,” said CDC Director Thomas Frieden, MD, MPH. “We have to keep our guard up. In Guinea, cases have increased and decreased in waves; we can’t stop until we stop the last chain of transmission.”

In one article on Liberia as a whole, Tolbert Nyenswah, LLB, MPH, assistant minister of health for Liberia, and colleagues detail trends based on data from the Liberian Ministry of Health and Social Welfare (MOHSW), Ebola treatment unit (ETU) admissions, and laboratory data. They also take into account reports from field investigators deployed in 12 of 15 counties in Liberia between October 25 and November 5.

Source: Centers for Disease Control and Prevention

 

MOHSW field teams conducted seven rapid-response investigations in hard-to-reach areas during that time, with aid from the World Health Organization, United Nations Childrens Fund, Emergency Health, the Peace Corps, and the CDC. They note that focal outbreaks in these hard-to-reach parts of the country are now frequent and will require a more flexible, rapid response to keep them from expanding.

Liberia's counties reported 2445 suspected, 1623 probable, and 2456 confirmed cases of EBV to MOHSW between March and the end of October. ETUs admitted a total of 4025 patients, 2956 (73.5%) of whom were classified as having EBV between June 5 and November 8, 2014. The system now has a total of 697 ETU beds available countrywide.

The number of specimen tests conducted in five laboratories increased from fewer than 50 a week in June and July to about 700 a week late September and early October, which is the apparent peak number, as testing has decreased since then. Overall, of a total of 5132 patients with laboratory data available, 2941 (57.3%) tested positive.

"The outbreak of Ebola in Liberia is complex and evolving," the authors write. "Trends in this analysis are based on ETU admissions and laboratory data and might underestimate case counts among persons who do not get tested, among persons who do not seek care in ETUs, and among persons in areas without ETUs."

Montserrado County

In an article on Montserrado County specifically, Nyenswah and colleagues detail the trends in the country's largest county, which includes the capital city Monrovia. About half of the country's cases have occurred in Montserrado County, which is home to 1.5 million people.

On the basis of the analysis of ETU admissions, laboratory test samples, and collection of dead bodies, the authors write that consistent declines of 53% to 73% in each data category occurred after a peak incidence in mid-September.

The number of ETU admissions hit maximum, so far, at 255 patients a week during the week of September 22. Admissions declined 67% to about 70 patients a week during the week of October 26.

During that time, the number of beds available in the county rose from fewer than 100 to more than 500, going from a shortage to an apparent surplus.

Laboratory data mirror the trend for ETU admissions. The number of patients testing positive for Ebola peaked at 79% during the week of August 18 and decreased to 51% during the week of October 20.

The body count for Ebola-related deaths peaked at 380 bodies collected during the week of September 15 and declined to 160 during the week of October 20.

"Ebola is far from eliminated in Montserrado, and the continued weekly discovery of new cases indicates that elimination from the county could be lengthy and progress could be reversed," the authors warn.

Lofa County

In an article on Lofa County, Aditya Sharma, MD, from the Epidemic Intelligence Service, CDC, and colleagues detail the trends in a county with one of the highest cumulative incidences in Liberia. MOHSW had 623 cases of EBV reported in the 300,000-population county by the end of October.

Peak ETU admissions occurred at 133 for the week ending August 16, up from 14 during the week ending June 14. Laboratory specimens testing positive for Ebola peaked at 35 (95%) of 37 during the period of June 8 to August 16 and fell to 21 (25%) of 85 during the period from August 24 to November 1. Related deaths peaked at 10 during the week of August 16 and fell to none November 1.

After the first reported cases of EBV in March, local government officials and partners developed and implemented a multiprong response, including:

  • encouraging changes in local persons handling the ill and burying the dead,

  • developing a dedicated ETU in the town of Foya,

  • establishing a local hotline and outreach teams from Médecins Sans Frontières and local health officials to rapidly transport persons to the ETU,

  • establishing a dedicated laboratory for rapid case identification,

  • active case-finding in which new cases are reported, and

  • training community health volunteers to trace individuals with known exposure.

"Transparency in activities and engagement with the community were central to the response strategy in Lofa County," the authors write.

They conclude, "The strategy in Lofa County might serve as a model for decreasing transmission of Ebola virus in areas where Ebola is still prevalent and spreading. Although transmission of Ebola virus might have decreased, new cases continue to be reported by the Lofa County Health Office and admitted to the Foya ETU. Partners in the response should remain vigilant and continue their activities to further enhance the control of Ebola in Lofa County."

Morb Mortal Wkly Rep. Published online November 14, 2014. Nysenswah Liberia full text, Nyenswah Montserrado full text, Sharma full text

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