High prevalence of drug resistance in animal trypanosomes without a history of drug exposure

Simbarashe Chitanga, T Marcotty, B Namangala, Peter Van den Bossche, J Van Den Abbeele, V Delespaux

    Research output: Contribution to journalA1: Web of Science-article

    Abstract

    BACKGROUND: Trypanosomosis caused by Trypanosoma congolense is a major constraint to animal health in sub-Saharan Africa. Unfortunately, the treatment of the disease is impaired by the spread of drug resistance. Resistance to diminazene aceturate (DA) in T. congolense is linked to a mutation modifying the functioning of a P2-type purine-transporter responsible for the uptake of the drug. Our objective was to verify if the mutation was linked or not to drug pressure. METHODOLOGY/PRINCIPAL FINDINGS: Thirty-four T. congolense isolates sampled from tsetse or wildlife were screened for the DA-resistance linked mutation using DpnII-PCR-RFLP. The results showed 1 sensitive, 12 resistant and 21 mixed DpnII-PCR-RFLP profiles. This suggests that the mutation is present on at least one allele of each of the 33 isolates. For twelve of the isolates, a standard screening method in mice was used by (i) microscopic examination, (ii) trypanosome-specific 18S-PCR after 2 months of observation and (iii) weekly trypanosome-specific 18S-PCR for 8 weeks. The results showed that all mice remained microscopically trypanosome-positive after treatment with 5 mg/kg DA. With 10 and 20 mg/kg, 8.3% (n = 72) and 0% (n = 72) of the mice became parasitologically positive after treatment. However, in these latter groups the trypanosome-specific 18S-PCR indicated a higher degree of trypanosome-positivity, i.e., with a unique test, 51.4% (n = 72) and 38.9% (n = 72) and with the weekly tests 79.2% (n = 24) and 66.7% (n = 24) for 10 and 20 mg/kg respectively. CONCLUSION/SIGNIFICANCE: The widespread presence of the DA-resistance linked mutation in T. congolense isolated from wildlife suggests that this mutation is favourable to parasite survival and/or its dissemination in the host population independent from the presence of drug. After treatment with DA, those T. congolense isolates cause persisting low parasitaemias even after complete elimination of the drug and with little impact on the host's health.
    Original languageEnglish
    JournalPLoS Neglected Tropical Diseases
    Volume5
    Issue number12
    Pages (from-to)e1454
    Number of pages5
    ISSN1935-2727
    DOIs
    Publication statusPublished - 2011

    Keywords

    • B780-tropical-medicine
    • Protozoal diseases
    • Animal diseases
    • Nagana
    • Trypanosoma congolense
    • Cattle
    • Vectors
    • Tsetse flies
    • Glossina
    • Drug resistance
    • Diminazene aceturate
    • Mutations
    • Drug effects
    • Exposure
    • Treatment
    • Isolation
    • Mice
    • In vivo
    • PCR-RFLP
    • Parasitemia
    • Zambia
    • Zimbabwe
    • South Africa
    • Africa-Southern

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