In late spring of 2009 and 2010, there were reports of severe black fly (Simulium spp., shown in Fig. 1) outbreaks in various counties in Mississippi, especially those in and around the Mississippi River Delta. Complaints were of black flies attacking multiple species of backyard poultry and causing high morbidity and mortality in affected flocks. At several affected locations, black flies were readily observed swarming around and feeding on birds. A large number of these parasites were easily trapped on fly strips (Fig. 2). Multifocal to coalescing cutaneous hemorrhagic lesions, consistent with fly bites, were seen on the birds. Upon necropsy examination, a large number of black flies were also observed in the digestive tract (Fig. 3). Although black flies may cause disease directly, such as cardiopulmonary collapse and anaphylactoid reactions, detection of Leucocytozoon in blood smears (Fig. 4) of affected birds prompted further investigations of this protozoan as a cause of disease. Leucocytozoon spp. are known to be transmitted by black flies and may be associated with morbidity and mortality in birds such as poultry. From June 2009 through July 2012, the investigation included a total collection of 1068 individual blood samples, representing 371 individual premises in 89 counties/parishes across Mississippi 59, Alabama 10, Louisiana 4, and Tennessee 16. Of the 371 premises where blood samples were collected, 96 (26%) were either positive or highly suspected to be positive for Leucocytozoon spp. by blood smear analysis, and 5 (1.2%) were positive for Haemoproteus spp. by blood smear analysis. Attempts to diagnose Leucocytozoon spp. by PCR analysis and sequencing were complicated by coinfections with two closely related haemosporidians (Haemoproteus spp. and Plasmodium spp.). A novel technique involving flow cytometry was also explored. This study discusses the black fly field outbreak, the involvement of haemosporidians, molecular methods for detection of both the black flies and blood parasites, and initial attempts at flow cytometry.

Investigaciones sobre brotes de ataques de la mosca negra y de subsecuentes hemosporidios aviares en aves de traspatio y en otras especies aviares expuestas.

A finales de la primavera del 2009 y del 2010, se recibieron reportes de brotes severos de la mosca negra (Simulium spp., mostrado en Fig. 1) en varios condados del estado de Mississippi, especialmente en aquellos localizados alrededor del Delta del río Mississippi. Los reportes indicaban ataques de moscas negras en múltiples especies de aves de traspatio y que causaban gran morbilidad y mortalidad en las parvadas afectadas. En varios lugares afectados, se observaron fácilmente moscas negras pululando alrededor y alimentándose de las aves. Un gran número de estos parásitos quedaron atrapados fácilmente en tiras para atrapar moscas (Fig. 2). Se observaron en las aves lesiones cutáneas hemorrágicas de naturaleza multifocal a coalescente, características de las mordeduras de la mosca. Durante el examen de necropsia, también se observó un gran número de moscas negras en el tracto digestivo (Fig. 3). Aunque las moscas negras pueden causar enfermedad directamente, como colapso cardiopulmonar y reacciones anafilactoid