Comparison of the use of Microscopy and Loop-mediated isothermal amplification (LAMP) in the Determination of the Epidemiology of the Re-emerging Bovine Trypanosomosis in Choma-Kalomo block of the Southern Province of Zambia
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Date
2012-06-18
Authors
Bukowa, Kizito M
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Abstract
A cross sectional study was carried out by microscopy and Loop-mediated isothermal amplification (LAMP), a novel molecular technique that amplifies target DNA under isothermal conditions, to determine the epidemiology of the re-emerging trypanosomosis in the Choma-Kalomo block, an important agricultural zone of the Southern Province of Zambia which was aerial-sprayed in 1987 in an attempt to eradicate tsetse flies and trypanosome infections. A total of 460 heads of cattle comprising 205 (44.6%) cows, 152 (33.0%) oxen, 56 (12.2%) female calves, 33 (7.2%) male calves and 14 (3.0%) bulls, were sampled from 13 crush pens. Blood collected from the superficial ear vein was used for microscopy and as a source of DNA in the trypanosome-specific LAMP reactions.
The overall prevalence of bovine trypanosomosis recorded by microscopy in the Choma-Kalomo block was 4.8%. Out of the 13 crush pens, bovine trypanosomosis was only detected in Nakalombwe (27.9%), Kakuse (18.6%) and Mbila A (8%). Further analysis of the same samples by LAMP revealed (i) an increase in the overall prevalence of bovine trypanosomosis to 12.8%, (ii) an increase in the sampling sites with trypanosome positive cattle from 3 by microscopy to 6, including Nakalombwe (53.5%), Kakuse (51.2%), Mbila A (36%), Fwentele (14.3%), Bungashiya (7.1%) and Maila Male (4.9%), (iii) detection of 6.8% mixed-infection cases of T. congolense and T. b. brucei while no mixed-infection case was detected by microscopy. Overall, LAMP was at least 2.5 times more sensitive than microscopy. Importantly, LAMP method was able to detect all parasitologically positive cases, in addition to the new cases it revealed, suggesting the reliability of LAMP, in addition to its superior sensitivity to microscopy.
Trypanosoma congolense accounted for 74.6% of total trypanosome infections recorded by LAMP in the Choma-Kalomo block. In agreement with previous reports, several cattle infected with T. congolense in this study were debilitated and anaemic. Adult cows seemed more likely to be infected with trypanosomes than any other category of cattle, possibly due to their being stressed through milking and at the same time being used for traction power, hence making them more susceptible to tsetse bite (less active) and trypanosomosis. Furthermore, trypanosome infections were mainly detected in sampling sites in close proximity to the Kafue National Park [Nakalombwe (53.5%) and Kakuse (51.2%)] where the tsetse vectors and wildlife reservoirs are in abundance.
Taken together, these results indicate a re-surgence of bovine trypanosomosis in the Choma-Kalomo block. Furthermore, data from this study suggest that LAMP is a much more sensitive and reliable technique for detection of bovine trypanosomes from field samples. Loop-mediated isothermal amplification is cheaper, quicker, simple and may easily be performed in the field. Thus, LAMP has the potential as an alternative molecular technique for detecting trypanosome infections from field specimens
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Keywords
Microscopy , Loop-Mediated Isothermal Amplification , Bovine Trypanosomiasis