Canine parvovirus type 2 (CPV‐2) emerged suddenly in the late 1970s as pathogen of dogs, causing a severe and often fatal gastroenteric disease. The original CPV‐2 was replaced by three antigenic variants, CPV‐2a, CPV‐2b and CPV‐2c, which to date have gained a worldwide distribution with different relative proportions. All previous studies conducted in Africa were based on partial VP2 gene sequences. The aim of this study was to provide a genome analysis to characterize the CPV strains collected in Nigeria, Africa. Rectal swab samples (n = 320) were collected in 2018 and tested by means of an immunochromatographic assay. Among the 144 positive samples, 59 were selected for further analyses using different molecular assays. The results revealed a high prevalence of CPV‐2c (91.5%) compared to the CPV‐2a variant (8.5%). The VP2 gene sequences showed a divergence from the strains analysed in 2010 in Nigeria and a closer connection with CPV strains of Asian origin. The non‐structural gene analysis evidenced amino acid changes never previously reported. The molecular analysis based on genomic sequences evidenced a geographical pattern of distribution of the analysed strains, suggesting a potential common evolutionary origin with CPV of Asian origin. This study represents the first CPV molecular characterization including all the encoding gene sequences conducted in the African continent and contributes to define the current geographical spread of the CPV variants worldwide.
Trypanosomosis is a major cause of mortality for dogs in Nigeria and treatment with diminazene aceturate has steadily become less effective, either as a result of low quality of the locally available diminazene preparations or of drug resistance. To investigate these alternatives, samples of locally obtained drugs were analysed for diminazene aceturate content and a strain of Trypanosoma brucei brucei was isolated from a diminazene-refractory dog in Nsukka, south-eastern Nigeria, and used to infect albino rats. The quality of diminazene aceturate-based preparations was variable, with two preparations containing less than 95% of the stated active compound. Rats infected with T. brucei isolated from the dog were treated 7 and 10 days after infection either with 7 mg/kg diminazene aceturate (intraperitoneally, once) or with 4 mg/kg pentamidine isethionate (intramuscularly, 7 consecutive days). Relapse rates were 100% for both trypanocides in the groups of rat treated 10 days post-infection, and 83% and 50% of rats treated 7 days after infection relapsed to diminazene aceturate and pentamidine isethionate, respectively. Careful consideration of physiological parameters showed that pentamidine was only marginally superior to diminazene aceturate as applied in this study. It was concluded that dogs in Nigeria are infected with genuinely diminazene aceturate-resistant trypanosomes that appear to be cross-resistant to pentamidine isethionate.
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.
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