41.   Laboratories with materials containing or likely to contain polio virus will then need to decide between transferring them to high security facilities or inactivating or destroying them.

42.   Most of them were infected by transfusions of blood containing the virus and by injections with used syringes.

43.   Most were infected by transfusions of blood containing the virus and by injections with used syringes.

44.   No new human cases have been reported since the chicken slaughter, and officials say they will know Wednesday whether the killing succeeded in containing the virus.

45.   No new human cases have been reported since the slaughter, and officials say they will know Wednesday whether the killing succeeded in containing the virus.

46.   Not only must there be a secure connection, but a home user is more likely to open up an e-mail attachment that could contain a virus.

47.   That method resulted in a product that could contain bovine viruses.

48.   The key to containing the virus, health officials said, was to educate a largely illiterate population on how to avoid catching Ebola.

49.   The international aid group Medecins Sans Frontieres, or Doctors Without Borders, is also helping to contain the virus.

50.   The international aid group, Medecins Sans Frontieres, or Doctors Without Borders, is also helping to contain the virus.