Abstract
Trypanosomes cause anaemia and are responsible for widespread morbidity and mortality particularly in imported breeds of animals found in sub-tropical and tropical parts of the world. Light microscopy and polymerase chain reaction (PCR) were used to detect trypanosomes in naturally infected Nigerian crossbred horses at Obollo-Afor abattoir, Udenu Local Government Area, Enugu State Nigeria. Blood was collected via the jugular outflow from a total of 200 horses of varying ages and either sex. Conventional procedures were followed during the PCR assay, parasite identification in wet mount, Leishman-stained thin blood and buffy coat smears on glass slides. Light microscopy revealed Trypanosoma species with an elongated, streamlined and tapered body, highly suggestive of T. brucei brucei or its subspecies T. evansi or T. equiperdum. PCR assay produced the expected fragment size of 700 bp specific for ITS-1 region of the 18SrRNA gene of Trypanosoma species in 4 (2%) of 200 blood samples against the routine blood and buffy coat smear examination, which revealed trypanosomes in 3 (1.5%) out of 200 blood samples. Sex and age were not significantly (p>0.05) associated with the trypanosome infection. One of the Trypanosoma infected anaemic horses had microcytic normochromic anaemia, high erythrocyte sedimentation rate and normal leukocyte count, while one of the Trypanosoma species infected non-anaemic horses had erythrocytic parameters and ESR values that are within the reference range, with leukocytosis. It was concluded that the prevalence of equine trypanosomosis was very low, and it’s characterized by mild to moderate anaemia in clinical cases.
Highlights
Trypanosomosis is a disease caused mainly by trypanosomes such as Trypanosoma vivax, T. congolense, T. brucei, T. equiperdum and T. evansi, and which is responsible for huge production losses in the livestock industry (Seidl et al, 1998)
Our polymerase chain reaction (PCR) amplicon size compared favourably with that of the positive control, Trypanosoma brucei brucei J10 and this suggests that the amplified species maybe T. brucei brucei, T. evansi or T. equiperdum
The finding of a trypanosome in one buffy coat smear could be due to low parasitemia or that the horse might be presymptomatic or a chronic carrier, as only one trypanosome was found on an entire thin blood smear (Figure 1)
Summary
Trypanosomosis is a disease caused mainly by trypanosomes such as Trypanosoma vivax, T. congolense, T. brucei, T. equiperdum and T. evansi, and which is responsible for huge production losses in the livestock industry (Seidl et al, 1998). Trypanosomes are extracellular, microscopic and elongated protozoan parasites. Received in revised form: 22 Sep 2021. From Volume 13, Issue 1, 2021, Notulae Scientia Biologicae journal uses article numbers in place of the traditional method of continuous pagination through the volume. The journal will continue to appear quarterly, as before, with four annual numbers
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