Investigation and sequence analysis of psittacine beak and feather disease virus and avian polyomavirus from companion birds in Windhoek, Namibia.

The commercial farming and trading of parrots and ornamental birds as companion animals are important economic activities in many countries. Some of the bird species farmed/traded are captured from the wild or are closely related to wild birds and therefore represent a risk of pathogen exchange/introduction. Beak and feather disease virus (BFDV) and avian poliomavirus (APV) are among the viruses with the biggest impact on companion bird populations and have been detected in different hosts worldwide. Despite their relevance for both domesticated and wild birds, our knowledge of BFDV and APV epidemiology remains limited in several African countries. In the present study, 143 cloacal swabs were collected from companion birds in Windhoek, Namibia, and tested by polymerase chain reaction for BFDV and APV. Of the samples tested, 35/143 (24.48%) tested positive for BFDV; 11/143 (7.69%) were positive for APV; and 6/143 (4.2%) tested positive for both pathogens. Positive amplicons, consisting of segments of the ORF1 and VP1 genes, were sequenced and compared with sequences from viruses identified in other countries. Four Namibian-only clades of BFDV were identified, loosely related to foreign strains, which suggest the occurrence of multiple introduction events in the past, potentially from South Africa, followed by local, independent evolution. In contrast, the Namibian APV sequences were identical to each other and form a single clade. In both instances, no correlation was observed between the sampling host and the viral phylogeny, suggesting the absence of host-specific adaptation and a remarkable, unconstrained viral circulation within Namibian borders. Therefore, while regulations and control measures developed against foreign strain introduction have proven to be effective over time, the spread of BFDV and APV within Namibia's borders appears undeterred. Additional resources should be dedicated to limit strain circulation in commercial farming facilities, markets and small-scale traders.

First genetic characterization of newcastle disease viruses from Namibia: identification of a novel VIIk subgenotype.

The complete sequences of the fusion (F) protein genes of six Newcastle disease virus (NDV) isolates from backyard poultry in Namibia in 2016 have been determined. The F gene cleavage site motif for all of the isolates was 112RRQKRF117, indicating that the viruses are virulent. A phylogenetic analysis using the full F gene sequence revealed that the viruses belong to a novel subgenotype, VIIk. This is the first genetic characterization of NDV isolates from Namibia, and the findings have important implications for Newcastle disease management and control in the region.

Novel genotype of Tritrichomonas foetus from cattle in Southern Africa.

Bovine trichomonosis caused by Tritrichomonas foetus is a significant reproductive disease of cattle. Preputial samples were collected using sheath washing technique in bulls in Namibia. Thirty-six trichomonad cultures were characterized using the TaqMan-probe commercial real-time polymerase chain reaction (PCR) diagnostic assay (VetMAX™-Gold Trich Detection Kit) and CYBR real-time PCR assay based on TFR3/4 primers. Diagnostic real-time PCRs and DNA sequencing of the internal transcribed region confirmed presence of T. foetus in 35 out of 36 samples. Multilocus genotyping using cysteine proteases (CP1, CP2, CP4, CP5, CP6, CP7, CP8, CP9) and malate dehydrogenase (MDH1) gene sequences demonstrate that the T. foetus in Namibia are genetically distinct from those characterized elsewhere. We report the discovery of a novel genotype of T. foetus in Namibian cattle, distinct from other T. foetus genotypes in Europe, South and North America and Australia. We suggest recognition of a 'Southern African' genotype of T. foetus. Identification of the new genotype of T. foetus demonstrates the need for wider global sampling to fully understand the diversity and origin of T. foetus causing disease in cattle or cats.