UTTAR PRADESH JOURNAL OF ZOOLOGY

Equine surra, caused by Trypanosoma evansi, is an important haemoprotozoan disease of working equids. This prospective descriptive pilot field study evaluated short-term changes after quinapyramine treatment and monitored T. evansi DNA detection during follow-up. Twelve indigenous horses from Ghazipur district, Uttar Pradesh, India, were included. Six naturally infected PCR-positive horses received a commercial quinapyramine preparation at 5.0 mg/kg body weight by subcutaneous injection, and six PCR-negative horses served as contemporaneous comparison animals. Blood collected on Days 0, 3, 7, 14, and 21 was examined by the microhaematocrit centrifugation technique, Giemsa-stained blood-smear examination, conventional PCR targeting a 196-bp invariable surface glycoprotein sequence, and indirect antibody ELISA. No parasites were detected microscopically in treated horses from Day 3 onward. PCR-negative status was recorded in 2/6 horses on Day 3, 4/6 on Day 7, and 3/6 on Days 14 and 21. The greatest observed PCR-negative proportion was therefore 66.7% on Day 7, followed by 50.0% on Days 14 and 21. The recorded group-level antibody relative percentage positivity increased from 75 on Day 0 to 90 and 91 on Days 3 and 7, respectively, and declined to 50 and 51 on Days 14 and 21. The findings indicate rapid suppression of microscopically detectable parasitaemia but incomplete and non-sustained PCR-negative conversion in some horses during the 21-day follow-up. Conventional PCR provided additional post-treatment information beyond microscopy, whereas antibody ELISA reflected continuing antibody reactivity rather than immediate parasitological cure. Larger controlled studies with longer follow-up and quantitative molecular testing are required to define treatment effectiveness more precisely.