Identification of Trypanosoma brucei gambiense in naturally infected dogs in Nigeria

Abstract

Background 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 . Methods 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. Results 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. Conclusions 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.

Molecular identification of Trypanosoma brucei gambiense in naturally infected pigs, dogs and small ruminants confirms domestic animals as potential reservoirs for sleeping sickness in Chad

“…This hypothesis is confirmed by the detection of T. b. gambiense in animals of the three HAT foci. The identification of natural infections of T. b. gambiense in pigs, sheep, goats and dogs confirm results obtained in some West and Central African HAT foci [ 8 , 9 , 16 , 17 , 28 , 40 – 43 , 50 , 51 , 56 ]. Moreover, experimental studies have demonstrated that all animal species found with T. b. gambiense can maintain this parasite for several months with the possibility of completing its cyclical transmission [ 35 ].…”

“…Previous investigations revealed several domestic and wild animal species as potential hosts of T. b. gambiense in West and Central African HAT foci [ 8 , 9 , 16 , 17 , 28 , 40 – 42 , 44 , 50 , 51 ]. For instance, natural infections of T. b. gambiense have been reported in sheep and goats in Cameroon, Equatorial Guinea and Congo [ 8 , 41 , 44 , 50 ], in pigs in Cameroon and Liberia [ 16 , 42 , 51 ], and in dogs in Liberia and Nigeria [ 16 , 56 ]. Besides these domestic species, several wild animal species have been also reported with natural infections of T. b. gambiense in Central African HAT foci [ 10 , 17 , 40 ].…”

Effect of treatment with trypanocides on Trypanosoma brucei induced oxidative stress and antioxidant enzyme activities in dogs

“…The death of the dogs in the infected untreated control dogs within 28 days PI can be due to the parasite's immunosuppressive effects, hence not allowing the dogs enough time to produce sufficient antibodies to fight the invading parasite. The clinical signs of corneal opacity, pale mucosae, staggering movement, ocular discharges, weakness and lethargy were consistent with findings of previous researchers (Ezeh et al, 2009;Umeakuana et al, 2019). The trypanocides cleared the parasitaemia following treatment by day 14 PI indicating that diminazene aceturate (DA) and isometamidium chloride (IMC) were efficacious in the treatment of T. brucei in dogs.…”

Molecular identification and prevalence of trypanosomes in cattle distributed within the Jebba axis of the River Niger, Kwara state, Nigeria

“…Several studies on trypanosomiasis transmission have been conducted in some parts of Nigeria [ 10 , 11 , 22 ]. However, to date, there is no published report on the prevalence of AAT in Kwara state.…”