J Vet Sci.  2010 Mar;11(1):27-34. 10.4142/jvs.2010.11.1.27.

Fatal cases of Theileria annulata infection in calves in Portugal associated with neoplastic-like lymphoid cell proliferation

• Branco S
• Orvalho J
• Leitao A
• Pereira I
• Malta M
• Mariano I
• Carvalho T
• Baptista R
• Shiels BR
• Peleteiro

• KMID: 1106154
• DOI: http://doi.org/10.4142/jvs.2010.11.1.27

Abstract

This study was carried out to investigate fifteen cases of acute lethal infection of calves (< or = 4 months of age) by the protozoan parasite Theileria (T.) annulata in the south of Portugal. Calves developed multifocal to coalescent nodular skin lesions, similar to multicentric malignant lymphoma. Infestation with ticks (genus Hyalomma) was intense. Theileria was seen in blood and lymph node smears, and T. annulata infection was confirmed by isolation of schizont-transformed cells and sequencing of hypervariable region 4 of the 18S rRNA gene. At necropsy, hemorrhagic nodules or nodules with a hemorrhagic halo were seen, particularly in the skin, subcutaneous tissue, skeletal and cardiac muscles, pharynx, trachea and intestinal serosa. Histologically, nodules were formed by large, round, lymphoblastoid neoplastic-like cells. Immunohistochemistry (IHC) identified these cells as mostly CD3 positive T lymphocytes and MAC387 positive macrophages. A marker for B lymphocytes (CD79alphacy) labeled very few cells. T. annulata infected cells in these nodules were also identified by IHC through the use of two monoclonal antibodies (1C7 and 1C12) which are diagnostic for the parasite. It was concluded that the pathological changes observed in the different organs and tissues were caused by proliferation of schizont-infected macrophages, which subsequently stimulate a severe uncontrolled proliferation of uninfected T lymphocytes.

Keyword

cattle; lymphoid cell proliferation; Theileria annulata; tropical theileriosis

MeSH Terms

Animals
Base Sequence
Cattle
Cattle Diseases/epidemiology/*parasitology/pathology
Cell Growth Processes/physiology
DNA, Protozoan/chemistry/genetics
Disease Outbreaks/*veterinary
Female
Immunohistochemistry/veterinary
Lymphocytes/parasitology/*pathology
Male
Molecular Sequence Data
Polymerase Chain Reaction/veterinary
Portugal/epidemiology
RNA, Ribosomal, 18S/chemistry/genetics
Sequence Analysis, DNA
Skin Diseases/epidemiology/parasitology/pathology/*veterinary
Theileria annulata/*isolation & purification
Theileriasis/epidemiology/parasitology/*pathology