A STUDY ON CONCOMITANT INFECTIONS AND SURVIVABILITY IN BLACK BENGAL GOATS WITH Peste des Petits Ruminants

Abstract

Peste des Petits Ruminants (PPR) is a severe contagious viral disease affecting small ruminants such as goat and sheep. The causative agent of PPR is a Morbillivirus which is enveloped having non-segmented single stranded RNA genome of negative polarity belonging to the family Paramyxoviridae. Clinically, the disease is suspected by severe diarrhoea, dehydration, respiratory distress, nasal and ocular discharges. The disease in goats is more severe than in sheep and mortality in goats due to PPR may reach up to 90%. Peste des Petits Ruminants virus is known to cause immuno-suppression in goats, rendering the animals more vulnerable to become infected with opportunistic organisms. Thus survivability in PPRV-infected goats, to a greater extent, is linked to the concomitant bacterial infections which can be treated with effective antimicrobials if their identity and prevalence are known. To have information on survivability in Black Bengal goats, naturally infected with PPRV along with the organisms causing probable concomitant infections in them - passed through 4 therapeutic regimens at the Chittagong Veterinary and Animal Sciences University (CVASU) veterinary hospital, 100 PPR-affected goats were investigated between May 2009 and April 2010. The disease was confirmed in laboratory by agar gel precipitation test (AGPT) using extracts from nasal swabs of live animals and lymphnode or spleen tissue- homogenates of necropsied animals as sources of PPRV-antigen, and locally raised hyper immune PPRV antiserum in healthy goat as a source of antibodies. Nasal swabs and blood collected from these goats were investigated by standard bacteriological procedures for the presence of probable concomitant organisms. For survivability, goats were observed for 14 days from the day of clinical-onset of PPR. Additionally, differential counts of leukocytes in these animals were also done. Of the observed PPR cases 56% of the goats were <1 year of age with the male and female proportions of 53 vs 47, respectively. Neutrophils and monocytes counts were significantly higher in PPRV infected goats belonging to the two age groups: < 1 year and > 1 year compared with healthy ones of the same age groups (p<0.05). However, in contrast, lymphocytes counts were lower in these PPRV infected goats (p<0.05). PPR affected goats were divided into 4 groups based on the treatments they had been received from the CVASU teaching veterinary hospital: Group I (treated with sulfur drugs), Group II (treated with amoxicillin), Group III (treated with strepto-sulfa preparations) and Group IV (treated with aminoglycoside such as gentamicin). Staphylococcus SPP. and Pasteurella multocida were the predominant organisms isolated from the PPRV infected goats. Regardless of treatment differences, survivability in PPR affected goats was 70% (95% confidence interval [CI] 58-79%). The survivability in goats belonging to treatment group IV was 86 % (95% CI 66-94%) which was significantly higher than that of group I and III (P=0.052). Counts for none of the members of leukocytes had any influence on the survivability of PPRV-infected Black Bengal goats (P>0.05).