Marburg haemorrhagic fever is an extremely rare disease that remains poorly understood. Information on the behaviour of Marburg virus once it enters a human population is sparse. As detailed in a fact sheet recently issued by WHO, the outbreak in Angola is one of only two large outbreaks of this disease that have occurred in indigenous African populations since the virus was first detected in 1967. The only other large outbreak, which began in late 1998 in the Democratic Republic of Congo, was confined to two sparsely populated villages in an isolated corner of the country, caused sporadic cases with small chains of transmission over two years, and never reached the intensity of transmission seen in just the past few weeks in Angola. The outbreak in Angola is not only the largest on record, with the highest fatality, but is also the first to occur in an urban setting.

Almost three decades of civil unrest have left Angola with a severely weakened health infrastructure, a hospital system in dire need of basic equipment and supplies, inadequate communication and transportation systems, and a population weakened by economic hardship. These weaknesses hamper containment efforts, which depend on active surveillance for cases, rapid detection and isolation in specially designated and equipped facilities, and rapid tracing of contacts.