Browsing by Author "Khaiseb, Siegfried"
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Item Genomic diversity of Rift Valley fever strains circulating in Namibia in 2010 and 2011(Viruses, 2020-12-16) Cosseddu, Gian Mario; Magwedere, Kudakwashe; Molini, Umberto; Pinoni, Chiara; Khaiseb, Siegfried; Scacchia, Massimo; Marcacci, Maurilia; Capobianco Dondona, Andrea; Valleriani, Fabrizia; Polci, Andrea; Monaco, FedericaOutbreaks of Rift Valley fever (RVF) occurred in Namibia in 2010 and 2011. Complete genome characterization was obtained from virus isolates collected during disease outbreaks in southern Namibia in 2010 and from wildlife in Etosha National Park in 2011, close to the area where RVF outbreaks occurred in domestic livestock. The virus strains were sequenced using Sanger sequencing (Namibia_2010) or next generation sequencing (Namibia_2011). A sequence-independent, single-primer amplification (SISPA) protocol was used in combination with the Illumina Next 500 sequencer. Phylogenetic analysis of the sequences of the small (S), medium (M), and large (L) genome segments of RVF virus (RVFV) provided evidence that two distinct RVFV strains circulated in the country. The strain collected in Namibia in 2010 is genetically similar to RVFV strains circulating in South Africa in 2009 and 2010, confirming that the outbreaks reported in the southern part of Namibia in 2010 were caused by possible dissemination of the infection from South Africa. Isolates collected in 2011 were close to RVFV isolates from 2010 collected in humans in Sudan and which belong to the large lineage containing RVFV strains that caused an outbreak in 2006–2008 in eastern Africa. This investigation showed that the RVFV strains circulating in Namibia in 2010 and 2011 were from two different introductions and that RVFV has the ability to move across regions. This supports the need for risk-based surveillance and monitoring.Item Molecular investigation of Porcine Circovirus type 3 infection in pigs in Namibia(Pathogens, 2021-05-11) Molini, Umberto; Marruchella, Giuseppe; Matheus, Frieda; Hemberger, Maria Yvonne; Chiwome, Bernard; Khaiseb, Siegfried; Cattoli, Giovanni; Franzo, GiovanniPorcine circovirus type 3 (PCV-3) infection is widely distributed in domestic pig populations in America, Europe, and Asia. However, no data is currently available about its presence and distribution in Africa. This study investigated the presence of PCV-3 in pigs (n = 122) in Namibia, by means of biomolecular methods. The pig samples collected (n = 122) were representative of the swine industry in Namibia, covering the major pig production facilities in the country. All of the samples tested were negative for PCV-3, and this indicated that the virus was either not present in the country or was circulating at low levels. Further studies are needed to better understand the distribution, if any, of PCV-3 in Namibia.Item The oryx antelope (Oryx gazella): An unexpected host for Porcine Circovirus-2 (PCV-2)(Pathogens, 2021-10-29) Molini, Umberto; Coetzee, Lauren Michelle; Hemberger, Maria Yvonne; Khaiseb, Siegfried; Cattoli, Giovanni; Dundon, William G.; Franzo, GiovanniFor several years after its discovery, Porcine circovirus 2 (PCV-2) represented a major threat to the swine industry through economic losses due to the associated clinical syndromes, decreased production performances in both symptomatic and asymptomatic animals and disease management costs. Widespread vaccination administration has largely reduced the impact of this infection and represents the most effective control measure. The efficacy of vaccination is threatened by the emergence of novel (or uncommon) PCV-2 genotypes. In addition to domestic pigs, PCV-2 has been detected in several other species, a fact which could have an impact on new variant emergence and maintenance. Considering this, the present study assessed the distribution of the minor PCV-2c genotype in non-Suidae ungulates in Namibia. Red hartebeests (Alcelaphus buselaphus caama) (n = 44), kudus (Tragelaphus strepsiceros) (n = 10) and oryxes (Oryx gazella) (n = 54), whose mediastinal lymph nodes were sampled after slaughtering during the period 2019–2021, were included in the study. Two oryxes (3.7%; 95% CI = 0.45–12.75%) were PCV-2-positive by PCR. Complete genome sequence was obtained for the two samples identifying them as PCV-2c genotype. The sequences were identical and shared a high percentage of identity (~99.9%) with those recently obtained from warthogs living in the same area. The present study confirms the presence of the PCV-2c genotype (previously considered extinct) in Namibian wild animal populations and demonstrates greater than expected PCV-2 host plasticity. Because of the role these niches can have in the maintenance and evolution of minor PCV-2 genotypes, more extensive and dedicated studies should be performed to prepare authorities to promptly react to potential emerging threats from these viruses.Item West Nile virus Seroprevalence in a selected donkey population of Namibia(Frontiers in Veterinary Science, 2021-06-18) Molini, Umberto; Franzo, Giovanni; Nel, Hannah; Khaiseb, Siegfried; Ntahonshikira, Charles; Chiwome, Bernard; Baines, Ian; Madzingira, Oscar; Monaco, Federica; Savini, Giovanni; D'Álterio, NicolaWest Nile Virus (WNV) is a mosquito-borne virus enzootically maintained in birds. However, it can incidentally infect other species, leading to sometimes severe clinical consequences like in horses and especially human beings. Despite the topic relevance, the presence and distribution of WNV are currently unknown in Namibia. Several countries implement surveillance systems based on virus detection in birds, mosquitoes, and vertebrate species including horses. The present study aimed to fill this knowledge gap by serologically evaluating WNV exposure in Namibian donkeys, whose population is remarkably bigger than the horse one. Forty-seven out of 260 sampled animals showed neutralizing antibodies against WNV (18.07% [95% CI = 13.59-23.30%]), demonstrating its circulation in all country territory, although, with apparent regional differences. On the contrary, no association with animal age or sex could be identified. The present study demonstrates the widespread presence of WNV in Namibia as well as the practical utility and effectiveness of donkeys as sentinels for infection surveillance. Due to clinical relevance, vaccination campaigns should be considered for horses of high economic or genetic value. Additionally, the burden of WNV infection on human health should be carefully evaluated.