where did the hepatitis b virus come from
Hepatitis B The virus is transmitted by exposure to infectious blood or body fluids.[1] Infection around the time of birth or from contact with other people's blood during childhood is the most frequent method by which hepatitis B is acquired in areas where the disease is common.[1] In areas where the disease is rare, intravenous drug use and sexual intercourse are the most frequent routes of infection.[1] Other risk factors include working in healthcare, blood transfusions, dialysis, living with an infected person, travel in countries where the infection rate is high, and living in an institution.[1][4] Tattooing and acupuncture led to a significant number of cases in the 1980s; however, this has become less common with improved sterility.[7] The hepatitis B viruses cannot be spread by holding hands, sharing eating utensils, kissing, hugging, coughing, sneezing, or breastfeeding.[4] The infection can be diagnosed 30 to 60 days after exposure.[1] The diagnosis is usually confirmed by testing the blood for parts of the virus and for antibodies against the virus.[1] It is one of five known hepatitis viruses: A, B, C, D, and E.
Black Death The Black Death is thought to have originated in the dry plains of Central Asia, where it then travelled along the Silk Road, reaching Crimea by 1343.[5] From there, it was most likely carried by Oriental rat fleas living on the black rats that were regular passengers on merchant ships, spreading throughout the Mediterranean and Europe.