A PCR TEST FOR AVIAN MALARIA IN HAWAIIAN BIRDS

The decline of native Hawaiian forest birds since European contact is attributed to factors ranging from habitat destruction to interactions with introduced species. Remaining populations of Hawaiian honeycreep ers (Fringillidae: Drepanidinae) are most abundant and diverse in high elevation refuges above the normal range of disease-carrying mosquito es. Challenge experiments suggest that honeycreepers are highly suscep tible to avian malaria (Plasmodium sp.) but resistance exists in some species. In order to detect low levels of malarial infection and quant ify prevalence of Plasmodium in high elevation natural populations of Hawaiian birds, a polymerase chain reaction (PCR) based diagnostic tes t was developed that identifies rRNA genes of Plasmodium in avian bloo d samples. Quantitative competitive PCR (QC-PCR) experiments indicate that the detection limit of our test is an order of magnitude greater than that reported for human malaria DNA blot tests. Compared with sta ndard histological methods, the PCR test detected a higher prevalence of diseased birds at mid-elevations. Malaria was detected in three spe cies of native birds living in a high elevation wildlife refuge on the island of Hawaii and in four species from Maul. Our results show that avian malaria is more widespread in Hawaiian forests than previously thought, a finding that has important conservation implications for th ese threatened species.