An apparent decrease in newly reported Ebola cases in Liberia — according to data released from the World Health Organization — seems more promising than it actually is, according to scientists at the Yale Schools of Public Health and Medicine and the Liberian Ministry of Health and Social Welfare.
The researchers, who published a mathematical model of Ebola transmission in The Lancet Infectious Diseases journal on Oct. 24, projected the number of Ebola cases in Liberia’s Montserrado County — the epicenter of the epidemic and home of capital city Monrovia — will skyrocket if the disease continues on its present course. There could be as many as 170,000 cases and 90,000 deaths by Dec. 15 unless further measures, such as beds for patients and protective kits for their families, are taken to control the disease, the model shows. These predictions appear to contradict data released Wednesday by the WHO, which reported that the rate of increase in cases has slowed, with fewer deaths reported in the last few days.
“The pace at which new cases were being reported has appeared to slow down,” said lead author Joseph Lewnard GRD ’19. “But since our research and as of Monday, there were new reports placing the number of cases in line with … the exponential growth our model suggested.”
According to Lewnard, the WHO numbers and the study’s predictions are not necessarily contradictory. Though the rate of growth is slowing down, it will likely pick back up again, he said.
Lewnard and his team created the model of Ebola transmission in Montserrado County using data of reported cases and deaths from the Ministry of Health in Liberia. The team accounted for the complex patterns of Ebola transmission between living and deceased patients, as well as the effect of current interventions.
They also controlled for irregularities and inaccuracies in reported numbers, which reflect the difficulty of identifying Ebola cases in a timely manner.
According to the model, up to 53,000 deaths could be averted by Dec. 15 if the international community deploys more beds for Ebola patients and protective kits for patients’ families in Montserrado County by Nov. 15. An increase in contact tracing of Ebola patients is also needed to save lives in the densely populated region.
Earlier interventions could have prevented even more deaths, the modeling shows. 137,000 deaths could have been averted by Dec. 15 if interventions had been initiated by Oct. 15 and 97,000 deaths had they been initiated by Oct. 31.
According to Lewnard, the study took into consideration transmission rate factors that previous studies had not taken into account.
“The innovation from our study was that we accounted not only for the fact that reporting occurred in sort of an incomplete fraction … but also that there’s delay in how cases get reported,” he said.
Incomplete information and delays could be one reason why the rate of recently reported Ebola cases and deaths appeared to decrease in recent days. However, spokesman for the WHO in Geneva Tarik Jasarevic said underreporting has been a problem for a long time and cannot account for the new decrease.
Jasarevic suggested that researchers should instead focus on the reasons behind underreporting — why Ebola patients are not going to treatment centers, for instance. Patients could be distrustful of health authorities, staying with their families or facing difficulties with transportation, he conjectured.
Fasil Tezera, head of the Doctors Without Borders mission in Liberia, agreed that it is too soon to interpret the reduction of Ebola cases in Liberia, such as the drop of admissions to the organization’s 250-bed Monrovia Ebola center to 80 patients.
“The present epidemic is unpredictable: We have seen a lull in cases in one area only to see the numbers spike again later,” Tezera said in an email. “More aid is needed on the ground.”
And according to School of Medicine professor of epidemiology and study author Frederick Altice, each week of inaction will result in more unnecessary deaths.
The most important steps to take are improving contact tracing and building sufficient Ebola treatment centers, Altice said, especially with no vaccines or cure available in the foreseeable future.
Lewnard agreed that health care workers should prioritize isolating Ebola cases and increasing the capacity to identify cases for isolation as quickly as possible.
Meanwhile in the U.S., states like New York and New Jersey have ordered mandatory 21-day quarantines of health care workers returning from West Africa in order to isolate potential cases of Ebola. Study author and postdoctoral associate in epidemiology Jorge Alfaro-Murillo said the U.S. should not quarantine people who do not have the disease but should instead be focusing its efforts on stopping Ebola transmission at its source in West Africa.
Alfaro-Murillo said his labmate, Ryan Boyko GRD ’18 — the public health graduate student who was admitted to Yale-New Haven Hospital with Ebola-like symptoms earlier this month and who was released from quarantine Wednesday evening — should not have been quarantined after traveling to Liberia and testing negative for the virus. Altice agreed that some current state policies are not founded on public health principles.
“Let’s keep the attention where it belongs — fixing the problem in West Africa,” he said.
As of Oct. 29, the Centers for Disease Control and Prevention reported 13,676 cases of Ebola worldwide.