The World Health Organization declared Sierra Leone free from Ebola transmissions on Saturday, as West Africa battles to stamp out the deadly virus that is holding on in neighboring Guinea. Nearly 4,000 people have died in Sierra Leone of Ebola since the outbreak began in late 2013. The organization said 42 days have passed since the last confirmed Ebola patient was discharged on Sept. 25 after two consecutive negative test results. Hundreds of people cheered…