Summary of Parasitic Protozoa in Ectothermic Vertebrates

## Introduction Plasmodium parasites infect many Anolis lizard species across the Caribbean, Central America, and parts of Mexico. This material summarizes patterns of morphology, host effects, ecology, and notable variations of Plasmodium (primarily P. floridense and related taxa) in Anolis hosts to help you learn how parasite traits vary by host species, infection phase, and geography. > Definition: Plasmodium in Anolis — blood-stage malaria parasites (merozoites, meronts, gametocytes) infecting Anolis lizards; measurements often report length, width, LW (projected area, in \(\mu m^2\)), and L/W ratio. ## Overview of life stages discussed - **Meront (schizont):** intracellular stage producing merozoites. Reported by dimensions, LW, and number of merozoites. - **Gametocyte:** sexual blood stage (micro = male, macro = female) with distinctive size and shape metrics. ### How morphology is reported (quick guide) - Length × width in \(\mu m\): e.g., $9.5 \pm 1.0 \times 5.7 \pm 0.9\,\mu m$ (range, N) - LW: projected area in \(\mu m^2\) - L/W: length-to-width ratio (shape elongation) - Relative sizes: comparisons to host cell nucleus and to normal erythrocyte nucleus ## Morphological variation by host and region Below are summarized patterns organized by representative host species and infection phase. ### Hispaniola: Anolis cybotes - Meronts: $6.0 \pm 1.0 \times 4.5 \pm 0.7\,\mu m$, LW $25.6 \pm 6.3\,\mu m^2$, mean ~10 merozoites. - Gametocytes: $9.5 \pm 1.0 \times 5.7 \pm 0.9\,\mu m$, LW $54.1 \pm 10.7\,\mu m^2$, L/W $1.72 \pm 0.46$. - Microgametocytes tend to be more elongate (higher L/W) than macrogametocytes. ### Dominican Republic: Anolis distichus and Anolis garmani (Jamaica) - A. distichus meronts slightly larger: $7.3 \pm 1.0 \times 5.4 \pm 0.6\,\mu m$, ~12.3 merozoites. - Gametocytes in A. distichus are larger and more elongate (L/W $2.23 \pm 0.80$) than in A. cybotes. - A. garmani meronts and gametocytes closely resemble those in A. cybotes: meronts $6.7 \pm 1.2 \times 4.7 \pm 0.7\,\mu m$. ### Puerto Rico: Anolis pulchellus and Anolis gundlachi - Active meronts in A. pulchellus larger: $9.0 \pm 1.8 \times 5.9 \pm 1.0\,\mu m$, ~13.3 merozoites, LW $52.1 \pm 9.4\,\mu m^2$. - Gametocytes larger: $11.3 \pm 1.6 \times 7.1 \pm 1.4\,\mu m$, LW $80.0 \pm 18.6\,\mu m^2$. - Microgametocytes are generally more elongate than macrogametocytes. ### Cayman Islands: Anolis conspersus - Meronts: $6.7 \pm 1.2 \times 4.7 \pm 0.6\,\mu m$, ~12 merozoites. - Gametocytes: $8.8 \pm 1.3 \times 5.3 \pm 0.8\,\mu m$, LW $46.5 \pm 9.0\,\mu m^2$. ### Bahamas: Anolis sagrei - Meronts: $7.8 \pm 1.4 \times 4.7 \pm 0.8\,\mu m$, ~15.1 merozoites (high variability). - Gametocytes: $11.3 \pm 2.5 \times 5.2 \pm 1.1\,\mu m$, L/W $2.27 \pm 0.80$; populations from different islands (Cat Cay vs North Bimini) differ in length and elongation. ### Central America / Mexico: Multiple Anolis species (e.g., A. lemurinus, A. tropidonotus, A. biporcatus) - Meront and gametocyte sizes vary with host species and infection phase (active vs chronic). Acute infections generally show larger meronts and higher merozoite counts than chronic infections. - Example: In Mexican A. tropidonotus (acute) meronts $8.1 \pm 2.1 \times 5.7 \pm 1.1\,\mu m$, ~14.9 merozoites; Honduran samples (near chronic) smaller meronts and fewer merozoites. ## Infection phase effects - Active (acute) infections: meronts and gametocytes are typically larger and produce more merozoites. - Chronic infections: gametocytes may be larger or show differing elongation depending on host species; meronts often smaller with fewer merozoites. > Definition: Active-phase infection — a stage with rapidly replicating meronts producing many merozoites and often larger parasite morphology. Chronic-phase infection — a later, lower-replication stage often with altered sizes and proportions. ## Effects on host erythrocytes and nuclei - Typical changes reported: hypertrophy (increase in size) or shrinkage of infe