When the young woman arrived at the government hospital in Kenema in Sierra Leone in late May, she had a high fever and was aborted. The hospital suspected she had contracted Lassa fever, because the viral disease is endemic in the region and often causes miscarriage. But Ebola virus disease, another hemorrhagic fever disease was spreading in neighboring Guinea for months, so when she started bleeding profusely, staff tested him for this virus as well. The results were positive, which makes its first confirmed case of Ebola in Sierra Leone.
Volunteers in protective gear bury a victim of Ebola in Kenema
PHOTO :. MOHAMMED Elshamy / ANADOLU AGENCY / GETTY IMAGES
the young woman, who eventually recovered, is now at the heart of a research tragic tale, but potentially important . In an online paper in this week Science , a collaboration led by Stephen Gire and Pardis Sabeti of Harvard University and the Broad Institute in Cambridge, Massachusetts, report the sequencing and analysis of genomes Ebola virus samples from 78 people in Sierra Leone who have been diagnosed with Ebola between late May and mid-June, including the young woman who came to the Kenema hospital. The complete 99-some sequences patients were sampled more than once to provide an overview of how the virus is changing in the course of the epidemic, which could help improve current diagnostic tests and, long term, guiding researchers working on vaccines and treatments.
study, however, also highlights the relentless toll taken by the epidemic on health care workers on the front lines. More than 50 co-authors from four countries have assisted in collecting and analyzing the viral sequences. Five of them have contracted the Ebola virus themselves and died.
The first diagnosed case in Sierra Leone infected person to the hospital, said Robert Garry, a virologist at Tulane University in New Orleans, Louisiana, who works with the Lassa center and research fever Kenema hospital is also co-author on the paper. But a health ministry team was immediately dispatched to the village where the woman about where and how she had been infected. They learned that she had attended the recent funeral of a traditional healer, herbalist who had been treating Ebola patients across the nearby border with Guinea.
The team found 13 other people who have been infected, all the women who had attended the funeral. These are the mourners that largely provoked the outbreak of Sierra Leone, which has sickened more than 00 and killed more than 30 people. Blood samples of 12 of those mourners and others infected allowed Gire, Sabeti and colleagues to track how the virus changed in spreading. "It is the first time that the actual development of Ebola virus can be observed in humans," says Sylvain Baize of the Pasteur Institute in Lyon, France, which block some of the first Ebola virus samples from patients in Guinea, where the outbreak originated current but was not involved in this project.
paidgenomic data also shed new light on how the virus has officially called EBOV-finished Africa West. EBOV, one of five ebolaviruses known to infect humans, has caused at least 12 homes in Central Africa and Gabon since 1976. Until this year, however, it has never been identified in Africa West.
Some researchers have hypothesized, based on early sequencing data, EBOV that had circulated for decades undetected in animals in the area. But the new analysis , reinforced by the unprecedented number of genomes, says another theory: that the virus spread through animal hosts, Central Africa within the last decade. Researchers are not sure what animal to blame, but the fruit bats are their leading suspects ( Science , 11 April, p. 140). At least the bat species a fruit known to carry ebolavirus has a range of the population that goes from Central Africa through Guinea.
Gire, Sabeti, and their colleagues found that in the current outbreak of the virus genome is changing quite rapidly, including in areas that are essential for PCR-based precision diagnostic tests. It will be important to keep track of these changes, Gire said, so that tests can be updated if necessary. Vaccines and treatments such antibody-based drug that zmapp that has been used in a handful of patients could also be affected by the types of changes identified researchers. (Sabeti said researchers zmapp his touch on new sequences his group has put online.)
The analysis reveals that the epidemic in Sierra Leone has been triggered by two distinct viruses, introduced in the Guinea at about the same time. It is unclear whether the herbalist was infected with both versions, or perhaps another participant Funeral arrangements were infected independently. An Ebola line disappears from samples taken from patients later in the epidemic, while a third line appears. This lineage linked to a nurse who was traveling to reach a hospital but died along the way, seems to have originated when one of the lines present at the burial has won a new mutation. The third line was extended, Garry said, via a truck driver who transported the nurse, and others who cared for her in the city where she died.
Further studies on the differences between the various Ebola lines could link these mutations in the virus behavior how lethal it is, and how easily it spreads, for example. "The document shows the latent potential of what these methods could do," said Roman Biek, who studies the evolution and ecology of infectious diseases at the University of Glasgow in the UK.
lacking the sequencing analysis samples are Ebola infected people in Liberia and Guinea. Stephan Günther of the Bernhard Nocht Institute for tropical medicine in Hamburg, Germany, said it has samples of Guinea in its laboratory, waiting to be sequenced once he and his colleagues can find the time. (This week Günther was in Nigeria, tracing contacts of Ebola patient there, that has been infected by a traveler from Liberia.) researchers at Liberia also collected samples, but focused on the attempt to slow the epidemic where it is spreading in the densely populated capital and shows no signs of slowing. (Congo is also on alert as Ebola emerged in a remote region in the northwest of the country. As Science to press, it is unclear who ebolavirus is causing this outbreak.)
Sabeti, who with his colleagues posted the virus sequences in public database as they are generated, said she hopes this work and the tragedy that struck his co-authors and other health workers will inspire other researchers to make their public data quickly both in this and future epidemic outbreaks. "We have to crowdsource the epidemic," she said. "The more information you enter in the hands of people who can help, the more likely you are to come up with a solution."
0 Komentar