The first sign of Hepatitis D was detected in 1978 when a strange and unrecognizable internuclear antigen was discovered during a liver biopsy of several Italians who suffered HBV infection. Scientists initially thought that it was an antigenic specificity of HBV, but they soon found that it was a protein from another disease altogether. They called it "Hepatitis Delta Virus" (HDV). This new virus was found to be defective. HDV needed HBV to act as a helper function in order for it to be detected. Normally Hepatitis B is transmitted through blood or any type of blood product. In South America Hepatitis D was found to be fatal. Scientists are still unsure in what way this disease was being transmitted throughout certain South American countries. Sexual contact and drug use are the most common means of transmission. HDV is still considered an unusual form of hepatitis. Agents of this virus resemble that of plant viroids. It is still hard to tell how many stereotypes exist because HDV is under the umbrella of HBV. HDV causes very high titers in the blood of people who are infected. Incubation of Hepatitis D typically lasts for thirty five days. Most often Hepatitis D is a co-infection with Hepatitis B or a super-infection with chronic hepatitis. In terms of super infections there are high mortality rates, ranging seventy to eighty percent; in contrast with co-infections which have a one to three percent mortality rate. There is little information with the ecology of Hepatitis D. Epidemics have been found in Venezuela, Peru, Columbia, and Brazil. People who are treated for Hepatitis B have been able to control Hepatitis D. People who have chronic HDB will continue to get HDV.