Tanzania, Kenya, Somalia and Sudan

00000000Epidemics occurred in Zanzibar in 1823 and 1870, although they were probably not dengue but chikungunya, as shown by Carey(10).

00000000A few cases were recorded from Mombasa during World War II(4). The results of a serological survey carried out in 1966 - 1968(16) showed that "dengue transmission has taken place in the coastal area of Kenya in the past". Antibodies for alphaviruses (Chikungunya and O'Nyong'Nyong) were also present in more than half of the tested sera of two of the three areas investigated.

00000000Between March and October 1982, DEN-2 virus isolates were obtained from seven of 43 sera from acutely ill patients(17,18). The epidemic spread along the coastal area of Kenya and neighbouring Somalia. Clinical investigations were few and medical personnel did not notice an increase of febrile illness, but, sometimes, only cases diagnosed as "clinical malaria". No survey was done to investigate an increase of mortality during the outbreak but some doctors noticed "an increase in cases of encephalitis and/or circulatory collapse", as had already been seen in the Seychelles Islands. The epidemic was extensive since the antibody prevalence rate rose from 7.6 per cent in June to 52 per cent in October.

00000000In Somalia, three cases were confirmed in expatriates in May 1983 by a specific rise of DEN-2 IgM, but in May 1984 no evidence of dengue transmission was found during limited surveillance(19).

00000000In January 1984 investigations were started in Port Sudan (Sudan), on the Red Sea coast, to determine "the cause of perennial epidemics of fever"(19). Twenty virus strains were isolated, of which 17 were DEN-2 and one was DEN-1. No other data were given concerning the clinical and epidemiological aspects of transmission.