Genetic analysis and emergence of canine parvovirus type 2c in South Eastern Nigeria.

BACKGROUND: Genetic analysis of canine parvovirus type 2 (CPV-2) variants circulating in South Eastern Nigeria was investigated. The original strain of CPV-2 emerged in 1978, mutated later to CPV-2a and has continued to be evolved. AIMS: To genetically characterize CPV-2 strains detected in dogs in South Eastern Nigeria and to phylogenetically group the viruses with existing sequencing data. METHODS: A total number of 82 rectal swabs were collected and stored in virus transport medium (VTM) from suspected cases of CPV-2 within the study area and were tested with polymerase chain reaction (PCR). RESULTS: Seventy-nine samples (96.3%) were positive for CPV-2 and sequence analysis of partial VP2 gene of 20 amplicons revealed circulation of CPV-2a (n=4) and CPV-2c (n=16) in the region. The obtained strains clustered together. However, the group was further divided into two clear clusters comprising of 2a and 2c strains. The vaccine strain and the CPV-2 reference strains from USA formed a monophyletic cluster. CONCLUSION: Canine parvovirus types 2a and 2c are co-circulating in South Eastern region of Nigeria and therefore, there is an urgent need for an improved vaccine to cover for the emerging strain (CPV-2c) in Nigeria.

Efficacy of ivermectin against gastrointestinal nematodes of pig in Nsukka area of Enugu State, Nigeria.

Ivermectin is a frequently used anthelmintic in pig production in Nigeria, because it is very effective against a broad range of endo- and ecto-parasites. However, gastrointestinal (GI) nematode infection still remains a major threat in pig production in Enugu state, Nigeria. Hence, the efficacy of ivermectin against GI nematode parasites of pig was evaluated in pig farms located in Nsukka area of Enugu State, using the Faecal egg count reduction test (FECRT). From each of 11 pig farms, 10 randomly selected female pigs were used for the study. Faecal samples were collected per rectum from each of the pigs for analysis, and their individual faecal egg count (FEC) per gram of faeces determined prior to treatment with ivermectine® (1% Ivemectin). A repeat sampling was carried out on the same pigs 12days post treatment (PT) to determine PT FEC. The efficacy of the anthelmintic, was calculated using the formular, FECR (%)=100 X (1-[T2/T1]). The ivermectin produced mean FECR% of 98.36%±0.43% against strongyle eggs and 100% against ascarid and trichurid in the farms. Consequently, at the level of the FECRT, the ivermectin used in this study was effective against GI nematode parasites of pigs in the study area, and no resistance was observed.

Efficacy of repeated doses of diminazene aceturate (Dinazene®) in the treatment of experimental Trypanosoma brucei infection of Albino rats.

The efficacy of repeated doses of Dinazene® in Albino rats experimentally infected with Trypanosoma brucei (Gboko strain) was investigated. A total of 30 adult female Albino rats weighing 130-190 g were used for the study. They were assigned to six groups (groups A-F) of five rats each. Groups A-D were infected intraperitoneally with 1.0 × 106 trypanosomes in 400 µL of PBS diluted blood while groups E (uninfected treated) and F (uninfected untreated) served as controls. The rats in the groups A-D as well as those in group E were treated with 7.0 mg/kg body weight at day 11 post infection. Groups B, C and D however received two, three and four repeated doses of the drug at weekly intervals following initial treatment. There was complete clearance of the parasite within 120 h post treatment. Parasitaemia, packed cell volume (PCV), total red blood cell (RBC) and white blood cell (WBC) counts, haemoglobin concentration (Hb), rectal temperature, and body weight were used to assay the efficacy of treatment. Following treatment and parasite clearance from the blood, there was improvement (P<0.05) in the values of parameters measured when compared to the uninfected controls. However, relapse infection was observed in the rats of group A, B and C, with a resultant decline in clinical condition and values of parameters used to assess efficacy. We concluded that four consecutive treatments using same dose at weekly intervals proved efficacious in the experimental management of T. brucei infection in rats.

Effects of Trypanosoma brucei infection and diminazene aceturate therapy on testicular morphology and function of Nigerian local dogs.

The effects of Trypanosoma brucei infection on testicular morphology and function and the changes associated with treatment of infected dogs with diminazene aceturate were studied using fifteen Nigerian adult male dogs. The dogs were randomly assigned into three groups A, B and C consisting of five dogs each. Groups A and B were infected with 1 × 10(6) trypanosomes and group C was the uninfected control. Following infection, parasitaemia levels were monitored daily whereas the rectal temperature, body weight, packed cell volume, scrotal circumference and serum testosterone levels were monitored weekly. At parasitaemia peak, dogs in group A were orchidectomised while dogs in group B were treated with 7.0mg/kg body weight of diminazene aceturate (DA). Dogs in groups B and C were later orchidectomised on day 73 of the experiment. The harvested testes and epididymides were weighed and the epididymal sperm reserves of all the dogs determined. Also the sperm quality (mass activity, sperm motility and sperm morphology) were determined. The testes were sectioned after processing and studied histomorphologically. Acute trypanosomosis was observed following infection. The low serum testosterone levels observed from day 14 post infection (pi) gradually improved following treatment. Testicular weight, epididymal weight and sperm quality were significantly low (p<0.05) in the infected dogs when compared to the control group but gradually improved following treatment. Histomorphological studies revealed testicular degeneration characterized by depopulation of seminiferous tubules and depletion of spermatogenic cells in dogs of group A whereas the tissue sections of the testes of dogs in group B were similar to those of the control group. It was therefore concluded that infection of dogs with T. brucei adversely affected testicular morphology and function. Treatment with diminazene aceturate reversed the reproductive abnormalities caused by the parasite.

Comparative serum biochemical changes in mongrel dogs following single and mixed infections of Trypanosoma congolense and Trypanosoma brucei brucei.

The serum activities of alkaline phosphatase (AP), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the serum levels of conjugated bilirubin (CB), blood urea nitrogen (BUN) and creatinine were studied following single and mixed infections of mongrel dogs with Trypanosoma congolense and Trypanosoma brucei brucei. Twenty mongrel dogs of both sexes aged between 3 and 6 months, and weighing between 2.5 and 5.9 kg were used for the study. The dogs were kept in clean metal cages in a fly-proof house and were fed and given water ad libitum. The twenty dogs were divided into four groups of five dogs each. Group I dogs were uninfected control, group II were infected with T. congolense, group III were infected with T. brucei brucei and group IV were infected with both T. congolense and T. brucei brucei. Each dog in the infected groups II and III was inoculated intraperitonealy (i/p) with 1.0 ml of PBS diluted blood containing 1.0×10(6) trypanosomes whereas each infected dog in group IV (mixed infection) was inoculated with 0.5 ml of the PBS diluted blood containing 0.5×10(6)T. congolense and 0.5 ml of the PBS diluted blood containing 0.5×10(6)T. brucei brucei i/p. Parasites were detectable in the blood of the infected dogs in groups II, III, and IV 10-13 days post infection (PI) with the mean pre-patent period (PP) of 12, 10, and 11 days respectively. Trypanosome infection caused a significant (P<0.05) increase in the serum activities of AP, ALT, AST and the serum levels of creatinine, CB, and BUN. The significant increases in the serum levels of CB, BUN, and creatinine and serum activities of AP and AST became noticeable from day seven PI in all the infected groups whereas that of ALT became noticeable from day 14 PI and increased continuously until the experiment was terminated. These increases however did not differ significantly (P>0.05) between the infected groups in most cases. It was thus concluded that single or mixed infection of mongrel dogs with T. congolense and T. brucei brucei resulted in significant increases in the serum activities of AP, AST, ALT and serum levels of creatinine, CB and BUN which in most cases did not differ significantly (P>0.05) among the infected groups.

Comparative efficacy assessment of pentamidine isethionate and diminazene aceturate in the chemotherapy of Trypanosoma brucei brucei infection in dogs.

The chemotherapeutic efficacy of diminazene aceturate (Berenil)--a standard veterinary trypanocide and pentamidine isethionate (PMI)--a human trypanocide was compared in dogs experimentally infected with Trypanosoma brucei brucei. Also, the activities of the drugs on some serum liver enzymes were evaluated before and after treatment to ascertain the relative safety of the drugs. Fifteen local dogs (mongrels) were used for the study. Three of the dogs were uninfected controls, and twelve were infected with a stock of T. brucei brucei. Three of the infected dogs were untreated controls, three were given diminazene aceturate (DA) at 7 mg/kg body weight intramuscularly (i/m), another three received pentamidine isethionate (PMI) at 4 mg/kg i/m on days 14, 17, 19, 27, 29, and 31 post infection (PI) and the remaining three dogs were also given same dose of PMI on days 14, 16, 18, 20, 22, 24 and 26 PI. Both trypanocides effectively cleared the parasites from the blood of the infected treated dogs. However, the infection subsequently relapsed at day 42 PI in one of the dogs in the DA treated group which later died at day 70 PI. Relapse infection was not recorded with the PMI treated groups although two dogs died in the PMI treated group II (treatment at days 14, 17, 19, 27, 29, and 31 PI) without showing relapsed parasitaemia. The packed cell volume (PCV), red blood cell (RBC) count, and haemoglobin (Hb) level which decreased significantly following infection, were reversed by the trypanocidal treatment. The reversal in the red cell values was faster in the PMI treated groups than in the DA treated group. The serum alkaline phosphate (SAP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) levels increased following infection and drug administration. The increase in the enzyme levels was greater in the DA treated groups than PMI treated groups. It was thus concluded that PMI given at 4 mg/kg i/m at days 14, 16, 18, 20, 22, 24, and 26 PI constituted a safe and efficient trypanocide and exhibited a superior trypanocidal action than DA in T. brucei brucei infected dogs.

Naturally occurring variability in some phenotypic markers and correlates of haemonchotolerance in West African Dwarf goats in a subhumid zone of Nigeria.

West African Dwarf (WAD) goats of the Nigerian subhumid zone generally show strong resistance and resilience to Haemonchus contortus in laboratory experiments, although a relatively small proportion are susceptible to infection. Little is known about these extremes of response phenotype in nature. Therefore, a survey was carried out of gastrointestinal nematode infections in WAD goats, with emphasis on abomasal worms, at three goat markets in Southern Nigeria during the rainy season. Faecal samples (n=1070) were collected weekly from goats between April and September, and 352 abomasa and small intestines from local abattoirs were examined. Total strongyle (prevalence=65.0%) and H. contortus (prevalence=64.3%) faecal egg counts (FEC) varied between the three markets, being highest throughout at Opi. FEC increased from April to peak in August. Based on raw FEC, 76.1% of goats had FEC of <100, and 4.7%>500. Adjustment of these figures for monthly and between-market differences, gave figures of 78.8 and 3.4%, respectively. H. contortus worm burdens (WB) showed a similar pattern with 67.9% of goats harbouring <200 worms and 8.2% >1000, and after adjustment 69.6 and 6.0%, respectively. Fecundity, based on eggs in the uterus, did not vary between markets or monthly, but fell with increasing WB. Trichostrongylus colubriformis was less frequent (prevalence=42.4%) but goats from Opi also carried higher WB, and worms were similarly highly aggregated in hosts. When the between-market and monthly differences for both species were controlled, a highly significant positive correlation between the species emerged. Therefore, although a small subset of goats, highly susceptible to H. contortus, exists in this breed, the majority show resistance under field conditions and the resistant phenotype is also resistant to T. colubriformis. Both species are highly aggregated in the susceptible subset of the population. While, we cannot yet exclude alternative explanations, our data are compatible with a strong genetic basis for this phenomenon.

A diminazene-resistant strain of Trypanosoma brucei brucei isolated from a dog is cross-resistant to pentamidine in experimentally infected albino rats.

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.

Susceptibility of local Nigerian and exotic chickens to infectious bursal disease by contact exposure.

One hundred 6-week-old susceptible cockerels were inoculated with a pathogenic strain of infectious bursal disease virus (IBDV) and kept in the same pen as 100 each of 6-week-old pullets, local chickens and broilers. The cockerels developed depression and diarrhoea on day 3 post inoculation (PI) and most of the pullets and some of the local chickens and broilers showed similar signs on day 4 PI. Loss in weight was severe and similar in the pullets and local chickens, being significantly greater than that in the broilers from days 3-11 PI. The total mortality was 85%, 66.7%, 30% and 20% for the pullets, cockerels, local chickens and broilers, respectively. The lesions were more severe in the pullets and local chickens than in the broilers. IBDV antigen and antibody were detected, respectively, in all the bursal and serum samples from the infected chickens tested. The contact exposure method used in this study simulates better what happens in nature than inoculation with IBDV. The reduced mortality observed among the local chickens, compared with that (61.5%) seen in earlier studies using intraocular inoculation of IBDV, may have been due to behavioural differences that tend to result in their ingesting a relatively low dose of the virus.

The response of Nigerian West African Dwarf goats to experimental infections with Haemonchus contortus.

One option for controlling haemonchosis in warm pastoral regions is improvement of resistance by selective breeding. Variation in acquired immunity to H. contortus and immunological correlates of infection were studied in West African Dwarf (WAD) goats. Following exposure to 5000 L3, 63 per cent of the inoculum established but 77 per cent of established worms were expelled by week 5. All infected animals were anaemic (day 14). When exposed to 2000L3, 36 per cent of the inoculum was still present (day 35) with no loss by day 49. Persisting primary infection worms survived a superimposed challenge (day 35), but their growth was slowed and resistance to challenge was significant. Most goats showed eosinophilia and parasite-specific IgG responses to primary infection, but only eosinophilia increased after challenge. No consistent associations were found between parasite burden and any immunological measures of infection, but parasite egg counts showed considerable variation. Overall, our results suggest that resistant genotypes exist among the WAD goat population.