Lizard Malaria Parasites

Plasmodium agamae: Gametocytes and asexuals 1

Two species of Plasmodium infect the rainbow lizard, Agama agama, over a large area of mesic Africa: P. agamae and P. giganteum. These are two of the earliest species of Plasmodium described, P. agamae by Wenyon in 1909 and P. giganteum by Theiler in 1903. P. agamae is shown in these photographs. It is the smaller parasite of the two, producing few merozoites per schizont. The gametocytes are also much smaller than those of P. giganteum and often have a wavy margin. The pictures above are from infections found in A. agama in Sierra Leone, west Africa. The geographic distribution of both species is given in Schall and Bromwich (Oecologia, 1994). The interaction between P. giganteum and P. agamae is also described in Schall and Bromwich.

P. agamae harms its lizard host, increasing the number of immature erythrocytes which results in a substantial decrease in the concentration of hemoglobin found in the blood of infected lizards. This most likely reduces the ability of the blood to deliver oxygen to tissues and infected lizard have a lower maximal oxygen use during activity and reduced running stamina. There is no reduction in the number of eggs produced by infected females, but if the infection is mixed with P. giganteum, the number of eggs in a clutch is reduced by 2/3. Details on the virulence of P. agamae are described in Schall (1990, Parasitology), Schall (1996, Advances in Parasitology), and Schall (2002 in The Behavioural Ecology of Parasites edited by E. E. Lewis, J. F. Cambell, and M. V. K. Sukhdeo).