Dengue in Africa

--------------
Michel Cornet

History

00000000The first epidemic attributed to dengue in Africa occurred in Cairo (Egypt) in 1779, as stated by Christie(1). This author also gives an account of epidemics starting in Zanzibar, on the East coast of Africa, in 1823 and 1870. The term dengue has its origin in Zanzibar, where the disease was called "denga" during the 1870 epidemic. In Durban (Natal, South Africa) a big epidemic was recorded in 1926 - 1927 by Edington(2). During World War II and immediately after, several epidemics were recorded from the coast of East Africa and the neighbouring islands(3-5). In West Africa, epidemics were recorded in Upper Volta in 1925(6), in Dakar (Senegal) in 1928(7) and on ships after calling at West African harbours(8,9).

00000000With our recent knowledge of arbovirus circulation in Africa, it is more likely that most of these epidemics were not true dengue but other arbovirus diseases which may cause urban epidemics. Carey(10) stated that the Zanzibar epidemics were due to chikungunya virus. Several flaviviruses have also been involved in epidemics during recent years (Zika, West Nile) as well as other arboviruses transmitted by anopheline mosquitoes, such as O'Nyong'Nyong, Bwamba or Tataguine.

00000000In fact, the first formally recognized epidemic of dengue in Africa was in Durban, where a retrospective serological survey showed evidence of anti-dengue 1 antibodies in people born before the epidemic(11). It must be mentioned that this is the only record of African dengue where severe haemorrhagic syndromes have been recognized(2).

00000000The first isolation of dengue virus (DEN) in Africa occurred in Nigeria, when a DEN-2 strain was obtained from a patient. Many other strains of DEN-1 and DEN-2 viruses were isolated from patients in Nigeria between 1966 and 1975. These results focused attention upon dengue in Africa, and in recent years the four virus types have been found in Africa. The most interesting observation concerns the discovery of an important sylvatic circulation of DEN-2 virus in at least four West African countries in 1980 - 81. Previously this sylvatic cycle was known to occur only in Malaysia and Viet Nam.