Marine Ornithology

Bird pathogens promote morbidity and mortality that affect bird population stability. In this context, the present study aims to detect blood intracellular parasites by molecular methods in four species of seabirds, Masked Booby Sula dactylatra, Red-footed Booby S. sula, Brown Booby S. leucogaster, and Magnificent Frigatebird Fregata magnificens, on the Brazilian coast. Blood samples were collected in the Archipelagos of São Pedro and São Paulo, Fernando de Noronha, Atol das Rocas, and Trindade and Martim Vaz. Genomic DNA was extracted with proteinase K digestion and purification with phenol and chloroform. For each sample, three independent polymerase chain reactions were performed with a positive control for Plasmodium and Haemoproteus. Corroborating other studies, our results indicate a low prevalence of Plasmodium and Haemoproteus parasitemia in this group of birds in the wild. We propose that the low parasitemia has occurred due to 1) the absence of the vector for transmission among individuals of these islands; 2) the low number of parasitized individuals detected in the colonies sampled; and 3) an effective immune response that prevents installation of the parasite. Only the Masked Booby and Magnificent Frigatebird have sufficient flight capacity to reach the Brazilian coast, but Masked Boobies rarely visit waters near the coast. Without vector studies at the archipelagos that were sampled, these hypotheses cannot be assessed.