Animal trypanosomosis is endemic in Nigeria, while the human disease caused by Trypanosoma brucei gambiense is rarely reported nowadays after efforts to bring it under control in the 20th century. The University of Nigeria Veterinary Teaching Hospital (UNVTH) is a reference centre located within the Nsukka area and serves Enugu and neighboring states, Benue, Kogi, Anambra and Delta. Among dogs presented to the UNVTH with canine trypanosomosis, T. brucei is frequently reported as the causative agent. However, this is by morphological identification under the microscope, which does not allow distinction of human-infective (T. b. gambiense) and non-human-infective (T. b. brucei) subspecies. Here, we used subspecies-specific PCR tests to distinguish T. b. gambiense and T. b. brucei. Blood samples were collected on FTA cards from 19 dogs presenting with clinical signs of trypanosomosis at the UNVTH from January 2017 to December 2018. All dogs had a patent parasitaemia. DNA was extracted from the FTA cards using Chelex 100 resin and used as template for PCR. All infections were initially identified as belonging to subgenus Trypanozoon using a generic PCR test based on the internal transcribed spacer 1 (ITS1) of the ribosomal RNA locus and a PCR test specific for the 177 bp satellite DNA of subgenus Trypanozoon. None of the samples were positive using a specific PCR test for T. evansi Type A kinetoplast DNA minicircles. Further PCR tests specific for T. b. gambiense based on the TgsGP and AnTat 11.17 genes revealed that two of the dogs harboured T. b. gambiense. In addition to trypanosomes of subgenus Trypanozoon, T. congolense savannah was identified in one dog using a species-specific PCR test for this taxon. Nineteen dogs presenting with canine African trypanosomosis at UNVTH were infected with trypanosomes of the T. brucei group and in two cases the trypanosomes were further identified to subspecies T. b. gambiense using specific PCR tests. Thus T. b. gambiense is one of the parasites responsible for canine African trypanosomosis in the Nsukka area of Nigeria and represents a serious danger to human health.

Hematological and serum biochemical profiles of animals are reflections of physiological disposition to their health status and production potentials. Findings in experimental studies on trypanosomosis may not translate directly to the expected findings in natural infections because of the effect of some variables like species and infecting dose of the parasite, nutritional status of the animal, concurrent infections, and stage of the trypanosomosis at the time of presentation to the clinic. Trypanosoma brucei and T. congolense infections in dogs have grave prognosis especially if the cases are not detected at their early stages. Clinical presentation, survivability of dogs treated with Diminazene aceturate as well as haematological and serum biochemical aberrations caused by natural infections with different Trypanosoma species were investigated with the view to identifying a variable or factor that could be used for prognostic evaluation in the treated dogs. Telephone numbers of the clients for dogs diagnosed with and treated against natural trypanosomes infections were collected and used to monitor the therapeutic outcomes. The clinical signs observed suggestive of late stage trypanosomosis were matched with the revelations from the case history. Significant (p ≤ 0.05) reductions in PCV, HB, absolute neutrophil, and significant (p ≤ 0.05) increase in monocytes count, serum urea, and creatinine were recorded in trypanosome infected dogs. Inability of clients to note the early clinical signs of infections with trypanosomes could have contributed to the low survival rate of the trypanosome-infected dogs even when treated.

Trypanosomosis is becoming a major health challenge to dogs in the sub-Sahara Africa including Nigeria, but minimal reports are available on the molecular characteristic of trypanosomes infecting dogs in Nigeria. We characterized trypanosomes detected in naturally infected dogs by PCR and sequences analysis of the partial region of the trypanosomes internal transcribed spacer-1of ribosomal RNA (ITS1 rRNA). Animals presented to the University of Nigeria Veterinary Teaching Hospital (UNVTH) in Nsukka, Nigeria for examination and treatment were sampled for laboratory tests. DNA was extracted from 21 blood samples obtained from dogs that were confirmed positive for trypanosome infection by microscopy. ITS-1 was PCR amplified and sequenced bi-directionally. Sixteen samples have good bands, though one of them had unreadable sequence. Analyses of the sequence data by BLAST search on NCBI identified T. congolense, T. brucei gambiense, and T. evansi in 4.8, 4.8, and 91.4%, respectively, from the analysed samples from the infected dogs. Although the top BLAST hits for T. brucei group were due to T. evansi and T. b. gambiense, there is not enough discriminatory power in ITS-1 to distinguish subspecies. The aligned sequences of the trypanozoon were less polymorphic. Phylogenetic trees inferred by unweighted pair group method with arithmetic mean (UPGMA) algorithms separated trypanozoon group from the T. congolense into two distinct clades. In conclusion, this study suggests that the trypanozoon group of trypanosomes cause more canine trypanosomosis in the study area and suggests inclusion of dogs in strategic planning for control and eradication of trypanosomosis in sub-Sahara African countries.