Partial genetic characterization of peste des petits ruminants virus from goats in northern and eastern Tanzania

Abstract

Peste des petits ruminants (PPR) is an acute viral disease of small ruminants. The disease was first reported in Tanzania in 2008 when it was confined to the Northern Zone districts bordering Kenya. The present study was carried out to confirm the presence of PPR virus (PPRV) in Tanzania and to establish their phylogenetic relationships. Samples (oculonasal swabs, tissues and whole blood) were obtained from live goats with clinical presentation suggestive of PPR and goats that died naturally in Ngorongoro (Northern Tanzania) and Mvomero (Eastern Tanzania) districts. The clinical signs observed in goats suspected with PPR included fever, dullness, diarrhea, lacrimation, matting of eye lids, purulent oculonasal discharges, cutaneous nodules, erosions on the soft palate and gums and labored breathing. Post mortem findings included pneumonia, congestion of the intestines, and hemorrhages in lymph nodes associated with the respiratory and gastrointestinal systems. PPRV was detected in 21 out of 71 tested animals using primers targeting the nucleoprotein (N) gene. Phylogenetic analysis, based on the N gene, indicated that PPRV obtained from Northern and Eastern Tanzania clustered with PPRV strains of Lineage III, together with PPRV from Sudan and Ethiopia. The findings of this study indicate that there are active PPRV infections in Northern and Eastern Tanzania, suggesting risks for potential spread of PPR in the rest of Tanzania.

Keywords: Tanzania; nucleoprotein gene; peste des petits ruminants; peste des petits ruminants virus; phylogeny.

Fig 1

Sampling sites for peste des petits ruminants virus (PPRV). A map of Tanzania showing areas where samples for PPRV were obtained from goats in (i) Northern Tanzania at villages (indicated by white circles) bordering the Serengeti National Park within the Ngorongoro Conservation Area and Loliondo Game Controlled Area and in Eastern Tanzania at Dakawa and Kauzeni villages (indicated by squares) within Mvomero district.

Fig 2

Clinical signs and post mortem findings in goats with peste des petits ruminants (PPR). (a) A goat with oculonasal discharges, periorbital edema and cutaneous nodules. (b) After skinning, cutaneous nodules were mainly confined within the skin with the exception of a few cutaneous nodules that could be observed below the skin (arrow head). Other postmorterm findings in goats with PPR included congestion of intestines (c), pneumonia (d and e) and froth formation (d, arrow head) and hemorrhage of the lymph nodes draining internal organs within thoracic and abdominal cavities (f).

Fig 3

Phylogenetic relationship of peste des petits ruminants viruses (PPRV). A neighbour-joining phylogenetic tree depicting the relationship of Tanzanian PPRV obtained from this study (indicated with circles) with other PPRV belonging to Lineages I-IV. Tanzanian PPRV from Northern Tanzania (Ngorongoro) and Eastern Tanzania (Dakawa) are not 100% identical and are clustered within Lineages III. Phylogeny was inferred following 1000 bootstrap replications and values <50% were not shown.