Many reports have been made on the presence of P. ovale throughout the world. However, a critical analysis of these reports by Lysenko and Bejaev (63) indicated that the natural distribution is in sub-Saharan Africa and the islands of the western Pacific. The parasite has been reported in New Guinea (5, 46, 68, 70) and the Philippines (3); it is apparently rare in the Philippines and only found on the island of Palawan (14). According to McMillan and Kelley (71), Heydon recorded P. ovale from the Duke of York Islands in 1923. Jackson (46) described two cases in Australian servicemen who had acquired their infections in New Guinea. It was also reported in Timor, Indonesia, for the first time in 1975 (43). The parasite was reported from Irian Jaya, two sites in West Flores and East Timor, Indonesia, but not present in Sumatra, Kalimantan, Java, and Sulawesi (7). Plasmodium ovale was reported in Moscow from a patient who had been infected in Melanesia (78). Reports from Southeast Asia suggest that P. ovale has been introduced to areas such as Vietnam (41), Thailand (60), and India (15). Whether or not it will be established on the mainland of Southeast Asia remains to be seen.
There are many reports of its distribution in sub-Saharan Africa. Lacan and Peel (62) in 1958 reported the presence of P. ovale in 25 children in French Equatorial Africa. In the neighborhood of Brazzaville, Republic of Congo, in 1978 to 1979, surveys among schoolchildren revealed a 24.5% infection rate with Plasmodium (1.9% of which was P. ovale) (74). In Gabon, in children 5 to 10 years of age, P. ovale was found in 2.4% of cases found infected with Plasmodium, while overall, the prevalence of infections with Plasmodium was 30% (84). Among 500 febrile children examined in the Pediatric Department of the General Hospital in Libreville, 29.2% had malaria, but P. ovale was "sparsely present" (85). In the Manyemen forest region of Cameroon, the prevalence of P. ovale was 10.5% (31). The parasite has been repeatedly reported from Nigeria (100). Fairley (34) reported P. ovale from a patient who returned to England after traveling to Nigeria, Gold Coast, Gambia, and Sierra Leone. In Sierra Leone, malaria infections have been reported to be due to P. ovale in from 0.5 to 1.0% of infected individuals (31, 100).
Because of the resistance of individuals with negative Duffy blood group to infection with P. vivax and the high prevalence of negativity in populations of West Africa, surveys reporting P. vivax may actually represent infections with P. ovale. Young and Johnson (101) found 2% of cases in Liberia to be P. vivax. It is probable that these were actually cases of P. ovale. Bjorkman et al. (10) conducted studies in an area of Liberia and found a prevalence rate in children for P. ovale of 9%. James et al. (50) reported that they had worked with strains of P. ovale from Nigeria and Belgian Congo. Afari (1) reported 2.7% of malarial infections due to P. ovale during a survey in a rural community in the central region of Ghana. Chin and Contacos (17) established a strain of P. ovale from a patient over a year after returning from service in Ghana.
Plasmodium ovale was reported to be extremely rare in southern Sudan and was absent in the north (80). Onori (81) carried out a survey in Uganda where, among 251 infections with P. ovale, the parasite was more often found in infants and adolescents. Infections with P. ovale have been reported in Zimbabwe (44, 93), Ethiopia (6), Zambia (99), Tanzania (66), and Natal (45). A relapse in an American after his return to the United States from Kenya has also been reported (82).
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