From the Clinic

There are 3 blood parasites that affect birds. There are some human blood parasites, but fortunately they are not something we typically have to worry about in the United States. This article will cover Leucocytozoon spp. Leucocytozoon spp. commonly infects both white and red blood cells. The red arrows in the first image point to examples of a lymphocyte (white blood cell) infected with Leucocytozoon spp. The yellow arrows in the second image point to examples of normal looking lymphocytes. You can see how difficult it would be to identify the kind of cell that is infected on the left. Typically, this blood parasite does not cause disease in birds.


Leucocytozoon spp. is transmitted via black flies. There are several methods to reduce a patient’s exposure to the black fly vector. While these animals are receiving veterinary care, proper housing should be provided. Indoor enclosures are ideal, but if the patient is outdoors some type of physical barrier, like a mesh screen, would be appropriate. Another method is to use a commercial product like a spray or powder to eliminate blackflies. Black flies range in size from 5-15 mm. They have short antennae, compound eyes, and fan shaped wings. Only the females will take a blood meal from a host. Males do not have the mouthparts required to take a bloodmeal. The third image is an example of a blackfly.


Case study GHOW 2017-08-01: This patient originally presented to SHRR because he was lethargic and was unable to stand. Upon closer examination, this bird was thin with a BCS (body condition score) of 1.5/5, dehydrated, and infected with flat flies. Body condition score is an evaluation of muscle and fat over the keel or breast bone. An ideal BCS score for a bird is 2.5-3/5. Gait and posture were evaluated. This patient walked on both feet, but seemed unsure of what to do or how to react. There was no head tilt or seizures. He was a suspect “young and dumb”. Birds categorized as “young and dumb” are young birds that are unsure of what to do or how to act. They are no longer with their parents but haven’t quite figured out how to survive on their own. Blood was drawn for a CBC (complete blood count). A CBC includes examination of a blood smear, WBC (white blood cell) count, WBC morphology, RBC (red blood cell) morphology, and platelet count. Upon evaluation of the blood smear, a 3+ Leucocytozoon was found along with anemia. This grading indicates that almost every white blood cell evaluated on the smear was infected with this specific blood parasite. This bird died within 24 hours of presentation. The cause of death is multifactorial. The age of the animal, BCS, anemia, and heavy blood parasite burden all contributed to the death.