Disease: Chicken malaria.
Crawford (1945) thought that jungle fowls are the natural hosts of P. gallinaceum. These are Gallus lafayetti in Ceylon, G. sonnerati in Sumatra and G. bankiva in India. Brumpt (1936), however, thought that the natural, wild host is still unknown. Jungle fowls are relatively resistant, but outbreaks of disease occur in domestic chickens introduced into areas where the parasite is endemic in wild birds.
Pheasants, partridges, peacocks and geese have been infected experimentally, but the duck, guinea fowl, pigeon, turtle dove, quail, buzzard, canary, English sparrow, Java sparrow (Padda oryzivora) and finch are resistant (Brumpt, 1936).
Location: Erythrocytes. The exo-erythrocytic stages are in endothelial cells.
Geographic Distribution: Southern Asia, Indonesia. P. gallinaceum was first seen by Crawford in Ceylon and named by Brumpt (1935) from material sent to him from Indochina. It has also been found in India (Rao, Das and Ramnani, 1951; Das, Rao and Ramnani, 1952) and Java, Sumatra and Celebes (Kraneveld and Mansjoer, 1953). It was reported from Egypt by Haiba (1948), but this record requires confirmation.
Morphology: The gametocytes and schizonts are round or irregular. The host cell nucleus is displaced but seldom expelled. The pigment granules in the gemetocytes are rather large and not very numerous. The schizonts produce 8 to 30 merozoites.
Life Cycle: The life cycle is similar to that of other Plasmodium species. The exo-erythrocytic stages in the endothelial or reticulo-endothelial cells of the spleen, brain, liver, etc. have been described by James and Tate (1937, 1938), James (1939) and Huff and Coulston (1944). The natural vectors are unknown, but various mosquitoes, including Aedes aegypti, A. albopictus, A. geniculatus and Culex quinquefasciatus, are potential vectors (Brumpt, 1936, 1936a; Vargas and Beltran, 1941). Huff (1954) listed 29 susceptible and 1 questionable species of which 19 are Aedes, 5 Armigeres, 2 (possibly 3) Culex, 1 Anopheles, 1 Culiseta and 1 Mansonia.
Pathogenesis: P. gallinaceum causes a serious disease with a high mortality rate in domestic chickens. The body temperature fluctuates, and anemia and splenomegaly are present. The birds may become paralyzed and die due to blocking of the brain capillaries by the exoerythrocytic stages.
Remarks: Beltran (1941, 1943a) and Crawford (1945) reviewed the history of research on this species. Because it lends itself well to experimental study and because the chicken is such an excellent laboratory animal, hundreds of papers have been written on it - according to Brumpt (1949), more than 600 between 1935 and 1948.