Avian Hematozoa in South America: a Comparison of Temperate and Tropical Zones

Abstract

We used screening techniques based on polymerase chain reaction (PCR) to explore the avian hematozoan parasites (Plasmodium spp. and Haemoproteus spp.) of two previously uninvestigated regions of continental South America. Comparisons of tropicalzone Guyana and temperate-zone Uruguay revealed that overall prevalence of Plasmodium and Haemoproteus species detected in a diverse sampling of potential hosts was significantly higher in Guyana. The difference in prevalence between the two geographic zones appears to be attributable to ecological differences rather than taxonomic sampling artifacts. Diversity of hematozoan haplotypes was also higher in Guyana. We found no relationship between hematozoan haplotype and host family sampled within or between regions. We found very few Plasmodium and no Haemoproteus haplotypes shared between the two regions, and evidence of geographic structuring of hematozoan haplotypes between the two regions. We suggest that a lack of hematozoan haplotype transmission between the two regions may be attributable to the migratory patterns of each region's avian hosts. Received 11 April 2005, accepted 21 November 2005. Resumen.Usamos tecnicas de investigacion basadas en reaccion en cadena de polimeros (RCP) para explorar hemoparasitos avicolas (Plasmodium spp. y Haemoproteus spp.) en dos regiones no investigadas de Sudamerica. Las comparaciones de la zona tropical de Guyana y de la zona templada de Uruguay revelaron que la frecuencia general de especies de Plasmodium y Haemoproteus encontrados en una muestra diversa de hospederos potenciales fue significativamente mas alta en Guyana. La diferencia en frecuencia entre las dos zonas geograficas aparentemente se debe a diferencias ecologicas que debido al muestreo taxonomico. La diversidad de hematozoos haplotipicos fue tambien mas alta en Guyana. No encontramos una relacion entre hematozoos haplotipicos y familias de hospederos muestreados dentro o entre las regiones. Encontramos solo algunos cuantos haplotipos de Plasmodium en comun entre las dos regiones, pero no se encontraron haplotipos de Haemoproteus, ni evidencia de una estructuracion geografica de haplotipos de hematozoos entre las dos regiones. Por lo que sugerimos que la ausencia de transmision de haplotipos de hematozoos entre las dos regiones puede ser atribuida a los patrones de emigracion, para cada region, de las aves hospederas. Hematozoan parasites (Plasmodium spp. and Haemoproteus spp.) are commonly found in blood smears from birds on every continent except Antarctica (Bennett et al. 1993). Hematozoan prevalence may differ between geographic locations, and climate may play an important role in this difference by influencing the density of vectors or potential hosts or the ease of transmission. Comparison of hematozoan parasites of temperate and tropical zones may reveal differences related to climatic factors. For example, Ricklefs (1992), surveying results from analyses based on blood smears, found a 2.6x greater infection rate in temperate than in tropical zones. Temperate and tropical 4 E-mail: durrantk@si.edu