Reports from Angola say the death toll from an outbreak of the Marburg virus - a dangerous and deadly form of hemorrhagic fever similar to ebola - has risen to 122, the second-highest casualty toll ever attributed to the disease.

Another 132 people suffering from symptoms of the Marburg virus have been hospitalized. Most cases of disease have been seen in the northern town of Uige, where the virus outbreak began in October.

A small number of cases have been confirmed in Luanda. Authorities are concerned that international travelers passing through the Angolan capital could unknowingly spread the virus over a wider area.

A health clinic in South Africa is urging travelers to avoid entering Angola for at least one week.

Experts from the World Health Organization and the humanitarian group Doctors Without Borders are working in Angola on attempts to contain the virus (which causes severe diarrhea, vomiting and, in many cases, uncontrolled internal hemorrhaging that often leads to death).

The Marburg virus was first identified in 1967, when it began spreading among laboratory workers in Europe who were working with monkeys. The worst previous outbreak occurred between 1998 and 2000 in what is now the Democratic Republic of Congo, 123 people died.