Stercorarian trypanosome

Sub genus: Megatrypanum

Trypanosoma theileri

Location and host

• These parasites are usually found in blood of cattle.

Morphology

• This is largest species of genus ‘Trypanosoma’ measuring 60-70 µm in length but forms upto 120 µm in length.
• Undulating membrane is prominent and free flagellum is present.
• Posterior end is long and pointed. Kinetoplast lies some distance from posterior end.
• Both trypomastigote and epimastigote forms occur in blood.

Life cycle

• Vertebrate hosts get infection when vector flies deposits faeces containing parasite on mucous membrane
• Small metacyclic trypanosomes changes into trypomastigote
• Trypomastigote then changes into epimastigote form.
• Epimastigote forms multiplies by longitudinal binary fission of epimastigote in lymph nodes
• Trypanosomes then develop into small metacyclic trypomastigote form in hind gut of flies.

Pathogenesis

• Ordinarily non-pathogenic but under condition of stress, it may cause severe disease and even death.
• Also, associated with ‘turning sickness’. This shows depressed milk production and abortion in cattle.
• This parasite has caused losses in cattle being immunized against rinderpest and other disease.

Clinical signs

• Infections are usually asymptomatic

Diagnosis

• BY incubating blood in culture medium in NNN ( Novy-macNeal-Nicolle) and other media.
• PM examination reveals yellow discoloration of tissues, enlargement of sub cutaneous L.N, congestion of liver and sero-sanguineous fluid in pericardial sac.

Treatment and control

• Not required usually
• Use of fly repellant to control flies or use of insecticide to control flies population.