(CNN) -- Angola's death toll from the Marburg virus has climbed to 173 and four more countries have been placed on alert, as health officials struggle to contain the deadly virus, according to the World Health Organization Web site.

The Democratic Republic of Congo, Nambia, Zambia and Congo have all been warned by the World Health Organization to be on alert for the Ebola-like virus.

Angola, which was not considered to be a 'hot zone' for the virus, is struggling to contain the outbreak that has spread to six provinces, concentrated in the north-western part of the country following the report of a case in Kuanza Sul.

Foreign governments and aid groups have rushed medical teams to the region.

The worst outbreak of the virus previously recorded killed 123 people in neighboring Congo between 1998 and 2000. That also was the last known outbreak.

Like Ebola, which also has hit Africa, Marburg is a hemorrhagic fever. It spreads through contact with bodily fluids and can kill rapidly. There is no vaccine.

In the recent outbreak in Angola, 75 percent of those dead are children under the age of five.

http://www.cnn.com/2005/WORLD/africa...ola/index.html