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.

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 ofTrypanosoma brucei bruceiisolated 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 ofTrypanosoma brucei bruceiwas 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 withT. bruceiisolated 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.

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.

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.