Splenomegaly in Papua New Guineans and in Japanese living in Papua New Guinea: report of research and exchange program of Osaka University with the South Pacific region.

Sizes of spleen and liver were studied by measuring spleen index calculated by multiplying the maximal length by the maximal width of the spleen and liver length at right mid-clavicular line below the costal margin using ultrasonography in 26 Papua New Guineans and in 25 Japaneses living in Papua New Guinea. In Papua New Guinean, spleen index and liver length were 77.4 +/- 9.9 cm2 and 5.4 +/- 0.7 cm, respectively. Their spleen index correlated inversely (p < 0.05) with hemoglobin level. In Japanese, spleen index and liver length were 24.5 +/- 2.1 cm2 and 0.8 +/- 0.3 cm, respectively and spleen index correlated positively with the duration of stay in Papua New Guinea (p < 0.05). These results indicate that the clinical and subclinical infections acquired in P.N.G. may play some role on the development of splenomegaly. Malaria is the prime suspect for the high prevalence of observed splenomegaly in both studied groups.