Differential Virulence and Pathogenicity of Canine Drug-Resistant Trypanosoma brucei brucei Field Isolates in Experimental Murine Infection.
Source: PubMed, NCBI / U.S. National Library of Medicine
African animal trypanosomosis remains a significant veterinary and economic threat in sub-Saharan Africa, worsened by rising multidrug resistance. In dogs, Trypanosoma brucei brucei infections are often acute and fatal, yet the relationship between drug resistance and pathogenicity remains poorly defined. This study aimed to compare the virulence and pathogenicity of three canine multidrug-resistant T. b. brucei field isolates from Southeast Nigeria using an experimental murine model. Twenty Sprague Dawley rats were randomly assigned to four groups (n = 5). Groups I-III received intraperitoneal inoculations of isolates from a veterinary hospital (VTH), Orie Orba dog market (Orba), and Nkwo Ibagwa dog market (Iba), respectively, while Group IV served as uninfected controls. Clinical progression, parasitaemia dynamics, haematological indices, and survival times were monitored. The isolates displayed strikingly heterogeneous pathogenic profiles. The Orba isolate was the most virulent, with the shortest pre-patent period (3-5 days), rapid parasitaemia onset, profound anaemia, and the lowest mean survival (14.8 ± 1.7 days). The VTH isolate showed attenuated virulence and extended survival (27.8 ± 2.5 days), whereas the Iba isolate exhibited intermediate characteristics (survival time: 22.6 ± 2.3 days). All infected rats developed progressive anaemia and leucocytosis, though severity varied by isolate. Multidrug
Abstract
African animal trypanosomosis remains a significant veterinary and economic threat in sub-Saharan Africa, worsened by rising multidrug resistance. In dogs, Trypanosoma brucei brucei infections are often acute and fatal, yet the relationship between drug resistance and pathogenicity remains poorly defined. This study aimed to compare the virulence and pathogenicity of three canine multidrug-resistant T. b. brucei field isolates from Southeast Nigeria using an experimental murine model. Twenty Sprague Dawley rats were randomly assigned to four groups (n = 5). Groups I-III received intraperitoneal inoculations of isolates from a veterinary hospital (VTH), Orie Orba dog market (Orba), and Nkwo Ibagwa dog market (Iba), respectively, while Group IV served as uninfected controls. Clinical progression, parasitaemia dynamics, haematological indices, and survival times were monitored. The isolates displayed strikingly heterogeneous pathogenic profiles. The Orba isolate was the most virulent, with the shortest pre-patent period (3-5 days), rapid parasitaemia onset, profound anaemia, and the lowest mean survival (14.8 ± 1.7 days). The VTH isolate showed attenuated virulence and extended survival (27.8 ± 2.5 days), whereas the Iba isolate exhibited intermediate characteristics (survival time: 22.6 ± 2.3 days). All infected rats developed progressive anaemia and leucocytosis, though severity varied by isolate. Multidrug resistance does not inevitably reduce T. b. brucei virulence. The MDR Orba isolate drove the most aggressive disease, indicating that resistant parasites can remain highly pathogenic. Our findings suggest that local selection pressures (drug exposure, host immunity) shape virulence traits. These results support the need for region-specific control strategies for animal trypanosomosis.