While the vast majority of cases have stricken residents of Angola's northern province of Uige, Marburg deaths also have occurred in hospitals in the country's capital, Luanda, and in another northern province, Cabinda. However, all of the ill have been people who apparently contracted the disease in Uige.

The latest victim of the Marburg virus, which is similar to Ebola, was a 19-year old woman who died Sunday in a hospital in Uige bringing the total number of fatalities to 121. At least 132 people are sick with the disease, but authorities have noted that the number of dead and ill may be underreported, since there is no way of knowing how many people might not have made it to a hospital.

The number of cases in Angola likely will make this epidemic the worst Marburg outbreak in history. The disease was first identified in 1967 and has occurred several times since then. The worst epidemic previously took place in the Republic of Congo, where 123 people reportedly died between 1998 and 2000.

Health Workers Battling to Contain the Epidemic

While the vast majority of cases have stricken residents of Angola's northern province of Uige, Marburg deaths also have occurred in hospitals in the country's capital, Luanda, and in another northern province, Cabinda. However, all of the ill have been people who apparently contracted the disease in Uige.

Authorities are making intense efforts to keep Marburg from spreading further in the country. The World Health Organization has sent a task force to the area, and other governments and non-governmental organizations have been sending health professionals to the scene and providing other assistance.

The Canadian government reportedly has provided a unique mobile laboratory to assist in making fast diagnoses of the disease.

Most Victims Are Children

Marburg is a form of acute hemorrhagic fever that has no specific cure. As many as three-fourths of the reported deaths have been children younger than five years of age, according to the World Health Organization. However, the number of cases among adults reportedly is on the rise. At least 6 health workers have died.

The virus is spread primarily through contact with bodily fluids. It causes symptoms similar to flu in the beginning -- headache, fever, vomiting, diarrhea -- but can rapidly progress to bleeding and death. About one in four cases are fatal.

Although the cause of the outbreak was unknown in the early weeks, the US Centers for Disease Control identified the mysterious disease as the rare Marburg virus.