Seroprevalence, and molecular detection of Brucella abortus in cattle tissues from an abattoir in Namibia

Brucellosis is a worldwide zoonosis that is endemic in Namibia. This study estimated seroprevalence of brucellosis, and determined the presence of Brucella infection in slaughtered cattle using the genus-specific 16-23S rRNA interspacer PCR (ITS-PCR), and the species-specific AMOS-PCR. Between December 2018 and May 2019, sera (n = 304), pooled lymph nodes (n = 304), and individual spleen (n = 304) were collected from slaughtered cattle from 52 farms. Sera were tested for anti-Brucella antibodies using the Rose Bengal test (RBT), and the complement fixation test (CFT). Seroprevalence was 2.3% (7/304) (RBT) and 1.6% (5/304) (CFT). Prevalence of positive herds was 9.6% (5/52). Lymph node (n = 200) and spleen (n = 200) samples from seronegative cattle tested negative for Brucella spp. DNA on ITS-PCR, but Brucella spp. DNA was detected in lymph nodes (85.7%, 6/7) and spleen (85.7%, 6/7) from RBT positive cattle. ITS-PCR confirmed isolates from lymph node (51.4%, 4/7) and spleen (85.7%, 6/7) as Brucella spp.; while AMOS-PCR and Brucella abortus species specific (BaSS) PCR confirmed the isolates as Brucella abortus, and field strains, respectively. Provision of adequate protective gear, and the promotion of brucellosis awareness among abattoir workers is recommended to prevent zoonotic infection.

Avian Influenza H5N8 Outbreak in African Penguins (Spheniscus demersus), Namibia, 2019

In January 2019, high mortalities were reported among African Penguins (Spheniscus demersus) in a breeding colony on Halifax Island, Namibia, Africa. Analysis of samples by reverse transcription quantitative PCR indicated the presence of highly pathogenic avian influenza (HPAI) subtype H5N8. Sequence analysis of the hemagglutinin and neuraminidase genes confirmed the presence of the virus in the birds and its high similarity to HPAI subtype H5N8 identified in South Africa in 2017. There have been no previous reports of HPAI H5N8 in Namibia.

Molecular characterisation of infectious bursal disease virus in Namibia, 2017

Between July and September 2017, samples collected from six unvaccinated chickens in Namibia were shown to be positive for infectious bursal disease virus (IBDV) by RT-PCR. Partial sequence and phylogenetic analysis of the VP1 and VP2 genes from six viruses revealed that they all belong to the very virulent pathotype (Genogroup 3) and are genetically very similar to IBDVs identified in neighbouring Zambia. This is the first molecular characterisation of IBDV in Namibia and has implications on the control and management of the disease in the country.

Investigation of infectious laryngotracheitis outbreaks in Namibia in 2018

Between July and August 2018, two outbreaks of infectious laryngotracheitis caused the death of over 116,000 commercial poultry (layers and broilers) near the city of Windhoek, Namibia. A third outbreak occurred in September 2018 in the north of the country approximately 800 km from the original outbreaks. Sample collection and molecular epidemiological analyses revealed that the outbreaks were most likely caused by poor vaccination practices leading to the reversion to virulence of an ILT vaccine strain. The analyses also indicate that inaccurate declarations were made by one of the farms involved and that illegal movement of animals most likely occurred.

Molecular characterization of lumpy skin disease virus in Namibia, 2017

Between January and July 2017, lumpy skin disease (LSD) outbreaks were reported in cattle in Namibia. DNA was extracted from skin biopsies taken from 32 cattle, and the RNA polymerase 30 kDa subunit (RPO30) gene of the LSD virus (LSDV) was successfully amplified by PCR. Phylogenetic analysis revealed that the newly sequenced LSDV isolates from Namibia were identical to LSDV isolates identified previously in Burkina Faso, Egypt, Greece, Niger, Serbia and South Africa. Given that only unvaccinated herds were affected by LSD, it is recommended that the current vaccination programmes in Namibia be re-evaluated to allow nationwide coverage.

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.