Listeria monocytogenes in ready to eat meat products from Zambia: phenotypical and genomic characterization of isolates.

The contamination of ready to eat foods (RTE) products due to Listeria monocytogenes could compromise the products safety becoming a great risk for the consumers. The high presence of L. monocytogenes in RTE products has been described worldwide, but few data are available about these products from African countries. The aims of this study were to report the presence of L. monocytogenes in Zambian RTE products, providing genomic characterization and data on similarity with African circulating strains using whole genome sequencing (WGS). A total of 304 RTE products, produced by different Zambian manufacturers, were purchased at retail, from major supermarkets located in Lusaka, Zambia, comprising 130 dairy and 174 meat products. L. monocytogenes was detected only in 18 (10.3%) RTE meat products of the 174 samples tested. The MLST analysis grouped the 18 L. monocytogenes isolates in 7 clonal complexes (CCs): CC1 (n = 5), CC2 (n = 4), CC9 (n = 4), CC5 (n = 2), CC121 (n = 1), CC155 (n = 1), and CC3 (n = 1). According to the cgMLST results, several clusters were detected, in particular belonging to hyper-virulent clones CC1 and CC2. Regarding the virulence factors, a complete L. monocytogenes Pathogenicity Island 3 (LIPI-3) was present both in the CC1 and CC3, in addition to LIPI-1. Several resistance genes and mobile genetic elements were detected, including Stress Islands, the bcrABC cassette and Tn6188_qac transposon, plasmids and intact prophages. Despite being a first preliminary work with a limited number of samples and isolates, this study helped to increase existing knowledge on contaminated RTE products in Zambia, confirming the presence of hyper-virulent L. monocytogenes CCs, which could play an important role in human diseases, posing a public health concern for consumers.

Identification of Mycoplasma mycoides subspecies mycoides from slaughtered cattle in two transboundary states of North­eastern Nigeria.

This study aimed to perform molecular typing of Mycoplasma mycoides subsp. mycoides from slaughtered cattle in Adamawa and Taraba States, north­eastern Nigeria. A total of four hundred and eighty (480) samples of lung tissues, nasal swabs, ear swabs and pleural fluids were collected from cattle at slaughter and processed according to standard laboratory protocols. Identification and confirmation were achieved with specific PCR and PCR­RFLP. An overall M. mycoides subsp. mycoides isolation rate of 6.87% (33/480) was obtained. In Adamawa State, 12 (10.91%) isolates of M. mycoides subsp. mycoides came from both, lung tissues and pleural fluids. While in Taraba State, 5 (7.14%) and 4 (5.71%) isolates of M. mycoides subsp. mycoides came from lung tissues and pleural fluids, respectively. The samples from nasal and ear swabs from the study states were negative for M. mycoides subsp. mycoides. Thirty­three out of the 37 culture positive isolates were confirmed to be Mycoplasma mycoides subspecies mycoides with the production of a band equivalent to 574­bp. Molecular typing with restriction endonuclease Vsp1 results in the two bands of 180­bp and 380­bp. In conclusion, the study has established an isolation rate of 6.87% for M. mycoides subsp. mycoides. Measures to strengthen movement control in order to minimise the spread of this dreaded disease of cattle were recommended.

Genetic Diversity of Rift Valley Fever Strains Circulating in Namibia in 2010 and 2011.

Outbreaks 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.

Contagious Bovine Pleuropneumonia: A Comprehensive Overview.

Contagious bovine pleuropneumonia (CBPP) is a respiratory disease of cattle that is listed as notifiable by the World Organization for Animal Health. It is endemic in sub-Saharan Africa and causes important productivity losses due to the high mortality and morbidity rates. CBPP is caused by Mycoplasma mycoides subsp. mycoides (Mmm) and is characterized by severe fibrinous bronchopneumonia and pleural effusion during the acute to subacute stages and by pulmonary sequestra in chronic cases. Additional lesions can be detected in the kidneys and in the carpal and tarsal joints of calves. Mmm infection occurs through the inhalation of infected aerosol droplets. After the colonization of bronchioles and alveoli, Mmm invades blood and lymphatic vessels and causes vasculitis. Moreover, Mmm can be occasionally demonstrated in blood and in a variety of other tissues. In the lung, Mmm antigen is commonly detected on bronchiolar and alveolar epithelial cells, in lung phagocytic cells, within the wall of blood and lymphatic vessels, inside necrotic areas, and within tertiary lymphoid follicles. Mmm antigen can also be present in the cytoplasm of macrophages within lymph node sinuses, in the germinal center of lymphoid follicles, in glomerular endothelial cells, and in renal tubules. A complete pathological examination is of great value for a rapid presumptive diagnosis, but laboratory investigations are mandatory for definitive diagnosis. The purpose of this review is to describe the main features of CBPP including the causative agent, history, geographic distribution, epidemiology, clinical course, diagnosis, and control. A special focus is placed on gross and microscopic lesions in order to familiarize veterinarians with the pathology and pathogenesis of CBPP.

Pro-Inflammatory Response of Bovine Polymorphonuclear Cells Induced by Mycoplasma mycoides subsp. mycoides.

Mycoplasma mycoides subsp. mycoides (Mmm) is the etiological agent of contagious bovine pleuropneumonia (CBPP), one of the major diseases affecting cattle in sub-Saharan Africa. Some evidences suggest that the immune system of the host (cattle) plays an important role in the pathogenic mechanism of CBPP, but the factors involved in the process remain largely unknown. The present study aimed to investigate the cell response of bovine polymorphonuclear neutrophils (PMNs) after Mmm in vitro exposure using one step RT-qPCR and Western blotting. Data obtained indicate that gene and protein expression levels of some pro-inflammatory factors already change upon 30 min of PMNs exposure to Mmm. Of note, mRNA expression level in Mmm exposed PMNs increased in a time-dependent manner and for all time points investigated; targets expression was also detected by Western blotting in Mmm exposed PMNs only. These data demonstrate that when bovine PMN cells are triggered by Mmm, they undergo molecular changes, upregulating mRNA and protein expression of specific pro-inflammatory factors. These results provide additional information on host-pathogen interaction during CBPP infection.

Prevalence of netB-positive Clostridium perfringens in Italian poultry flocks by environmental sampling.

Clostridium perfringens type G is one of the pathogens involved in enteric diseases in poultry. NetB, a pore-forming toxin, is considered the main virulence factor responsible for necrotic enteritis during C. perfringens infection. We carried out a field study involving 14 farms to evaluate the occurrence of netB-positive C. perfringens and the impact of infection in Italian poultry flocks. Environmental samples (n = 117) and 50 carcasses were screened by microbiologic and molecular methods. Microbiologic investigations yielded 82 C. perfringens isolates. DNA was extracted from all samples and screened for α-toxin and NetB encoding genes by real-time PCR. The C. perfringens α-toxin gene was detected in 151 of 167 extracts (90.4%), and 31 of 151 (20.5%) were netB gene positive also. Sixteen isolates from a turkey flock with mild enteric disorders were also netB positive, demonstrating their occurrence not only in broiler but also in turkey flocks. A pulsed-field gel electrophoresis protocol was optimized to evaluate the diversity among isolates and revealed high genetic heterogeneity. The complete NetB toxin-coding gene of 2 C. perfringens isolates from turkey and broiler flocks were analyzed and showed very high relatedness with analogous sequences worldwide.

Brucellosis and chlamydiosis seroprevalence in goats at livestock-wildlife interface areas of Zimbabwe.

In Zimbabwe, there have been no chlamydiosis and limited brucellosis studies in goats. This study was conducted to determine the seroprevalence and risk factors of the two diseases in goats at three different livestock-wildlife interface areas: porous, non-porous and non-interface in the south-eastern lowveld of Zimbabwe. Collected sera (n = 563) were tested for Brucella antibodies using the Rose Bengal plate test (RBPT) and the complement fixation test (CFT); and for Chlamydia abortus antibodies using the CFT. All tested goats were negative for Brucella antibodies. Overall, chlamydial seroprevalence was 22%. The porous [c2 = 9.6, odds ratio (OR) = 2.6, p = 0.002] and non-porous (c2 = 37.5, OR = 5.8, p < 0.00001) interfaces were approximately three and six times more likely to be chlamydial seropositive than the non-interface area, respectively. Chlamydial seroprevalence was not associated with sex (c2 = 0.5, OR = 1.2, p = 0.5), abortion history in female goats (c2 = 0.7, OR = 1.3, p = 0.4), keeping goats with cattle (c2 = 0.2, OR = 1.5, p = 0.7) or flock size (c2 = 0.03, OR = 1.4, p = 0.9). Our study provides the first serological evidence of chlamydiosis in goats in Zimbabwe and the results suggest that proximity to wildlife is associated with increased chlamydial seropositivity. Further studies are required to determine the role of chlamydial infection on goat reproductive failure and that of wildlife on C. abortus transmission to domestic ruminants.

"SILAB for Africa": An Innovative Information System Supporting the Veterinary African Laboratories.

Introduction: To support African veterinary laboratory services, the Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise puts in place an operational system called "SILAB for Africa" (SILABFA); this is a web application used by a laboratory information management system to support laboratory diagnostic activities and to meet the needs of various African countries. SILABFA was designed to collect and manage all necessary information on samples, tests, and test results.Methods: The system involves the entry of sample data on arrival, the tracking of samples through the various sections of the laboratory, and the collection of test results. It automates the generation of test reports and monitors outbreaks through data interrogation functions and eliminates multiple registrations of the same data on paper records. SILABFA is currently installed in Namibia, Botswana, Zambia, Zimbabwe, Tanzania, Uganda, Kenya, Ethiopia, and Cameroon, and installation in Senegal and Ivory Coast is planned for the next few months. After some years of SILABFA usage, it was natural to want to utilize more and more data collected in a homogeneous and consistent way for epidemiological purposes and to cover informative debts toward ministries and other organizations.Conclusion: To improve the availability of good, detailed, and reliable data, as the epidemiological information, SILABFA has been linked to the local animal identification, registration, and traceability system and other relevant national information systems.

Virulence gene profiles of rabbit enteropathogenic Escherichia coli strains isolated in Northern Italy.

The virulence gene profile of 26 rabbit enteropathogenic Escherichia coli strains, isolated from 17 colibacillosis outbreaks located in two regions of Northern Italy, was determined using an Echerichia coli virulence DNA microarray. All strains were classified according to their determined biotype, sero- and phylo-group. The distribution of virulence genes encoding for the Locus of enterocyte effacement (LEE), LEE type III secretion system (T3SS), non-LEE T3SS translocated proteins and adherence factors was also determined. All strains but one belonged to phylogroups A and B1. A prevalent association between the O103 serogroup with the rhamnose-negative phenotype (biotype 12 or 14) was found. The most prevalent LEE profile found in tested strains was ler/cesT/espA-1/espB-3/tir-1/eae(beta)/espD-2/escN/eprJ. All strains possessed either the adhesive factor rabbit-2 (afr/2) or the plasmid Rabbit adherence locus (ral) gene and 24 of them an additional individual or combined set of colonization factors efa1/lifA, lpfA and paa genes. Finally, the combined or single presence of a set of LEE and/or non-LEE effector proteins encoding genes, namely espG, cif, map and nle family genes, attested to the genetic potential of investigated strains to induce pathologic lesions to the host. The application of microarray-based technologies in assessing the genetic profile of rabbit E. coli is a reliable, cost-effective candidate for large scale investigations in monitoring programs aimed to survey the circulation of pathogenic strains within rabbit production units, their zoonotic genetic potential and to select E. coli strains eligible for vaccinal prophylaxis in fattening rabbit production.

Polymorphonuclear cells and reactive oxygen species in contagious bovine pleuropneumonia: New insight from in vitro investigations.

Reactive oxygen species (ROS) are suggested to play a role in the pathogenesis of contagious bovine pleuropneumonia, a severe respiratory disorder caused by Mycoplasma mycoides subsp. mycoides (Mmm). The present study investigated the generation of ROS by different strains of Mmm, as well as their effect on the oxidative response of bovine neutrophils. The production of ROS was indirectly measured using a luminol-based chemiluminescence assay. Our results confirm that Mmm can produce ROS via the metabolism of glycerol, significant differences existing between African and European strains. Mmm was capable of adhering to the external surface of neutrophils. Interestingly, Mmm enhanced the respiratory burst of bovine neutrophils. This activity was particularly pronounced with the African field strain and in presence of glycerol. Taken together, our data argue in favour of a major role for neutrophils as the main source of ROS in contagious bovine pleuropneumonia.

Sero-prevalence of chlamydiosis in cattle and selected wildlife species at a wildlife/livestock interface area of Zimbabwe.

A study was conducted to investigate the seroprevalence and associated risk factors of Chlamydia abortus infection in cattle and some selected wildlife species at selected interface areas at the periphery of the Great Limpopo Transfrontier Conservation Area in Zimbabwe. Three study sites were selected based on the type of livestock-wildlife interface, porous livestock-wildlife interface (unrestricted), non-porous livestock-wildlife interface (restricted by fencing), and livestock-wildlife non-interface (totally absent or control). Sera were collected from cattle aged ≥ 2 years representing both female and intact male. Sera were also collected from selected wild ungulates from Mabalauta (porous interface) and Chipinda Pools (non-interface) areas of the Gonarezhou National Park. Sera were tested for antibodies to Chlamydia abortus using a CFT. A X 2 test was used to assess differences between categories and p < 0.05 was considered as significant. In cattle, the overall seroprevalence was 32.7% (327/1011; 95% CI 29.5-35.3). A significantly lower seroprevalence was recorded for the porous interface (24.2%) compared to the non-porous (42.5%) (p < 0.0001) and the non-interface (36.2%) (p = 0.001). Overall, the wet season recorded a significantly (p = 0.015) higher seroprevalence than the dry season. In wildlife, antibodies were detected in buffaloes (47.7%) and impalas (43.8%) but not in kudus. Buffaloes from Chipinda Pools (53.4%) had a significantly (p = 0.036) higher seroprevalence than those from Mabalauta (26.1%). The results established the presence of chlamydiosis in cattle and selected wildlife and that independent infections may be maintained in buffalo populations. Further studies are required to clarify chlamydiae circulating between cattle and wildlife.

Respiratory explants as a model to investigate early events of contagious bovine pleuropneumonia infection.

Contagious bovine pleuropneumonia (CBPP) is a severe disease caused by Mycoplasma mycoides subsp. mycoides (Mmm). Knowledge on CBPP pathogenesis is fragmented and hampered by the limited availability of laboratory animal and in vitro models of investigation. The purpose of the present study is to assess respiratory explants as useful tools to study the early stages of CBPP. Explants were obtained from trachea, bronchi and lungs of slaughtered cattle, tested negative for Mycoplasma spp. and for the major bacterial and viral respiratory pathogens. The interaction of Mmm with explant cells was studied by immunohistochemistry (IHC), double-labelling indirect immunofluorescence (DLIIF) and laser scanning confocal microscopy (LSCM). Mmm capability to survive and proliferate within the explants was evaluated by standard microbiological procedures. Finally, the putative cellular internalization of Mmm was further investigated by the gentamicin invasion assay. IHC and DLIIF indicated that Mmm can colonize explants, showing a marked tropism for lower airways. Specifically, Mmm was detected on/inside the bronchiolar and alveolar epithelial cells, the alveolar macrophages and the endothelial cells. The interaction between Mmm and explant cells was abolished by the pre-incubation of the pathogen with bovine anti-Mmm immune sera. Mmm was able to survive and proliferate in all tracheal, bronchial and lung explants, during the entire time course of the experiments. LSCM and gentamicin invasion assay both confirmed that Mmm can enter non-phagocytic host cells. Taken together, our data supports bovine respiratory explants as a promising tool to investigate CBPP, alternative to cattle experimental infection.

Lung lesion score system in cattle: proposal for contagious bovine pleuropneumonia.

Contagious bovine pleuropneumonia (CBPP) is a severe infectious disease caused by Mycoplasma mycoides subsp. mycoides. The peculiar pathological features of CBPP make desirable the assessment of ad hoc score methods to grade the disease in the affected animals. Thus, the present work aims to assess a new lung score system for CBPP. Our results indicate that the present score system strongly correlates with that previously published by Turner and could be effectively used in CBPP-affected animals.

Seroprevalence of brucellosis in cattle and selected wildlife species at selected livestock/wildlife interface areas of the Gonarezhou National Park, Zimbabwe.

A study was conducted to investigate seroprevalence and risk factors for Brucella species infection in cattle and some wildlife species in communities living at the periphery of the Great Limpopo Transfrontier Conservation Area in south eastern Zimbabwe. Three study sites were selected based on the type of livestock-wildlife interface: porous livestock-wildlife interface (unrestricted); non-porous livestock-wildlife interface (restricted by fencing); and livestock-wildlife non-interface (totally absent or control). Sera were collected from cattle aged≥2years representing both female and intact male animals. Sera were also collected from selected wild ungulates from Mabalauta (porous interface) and Chipinda (non-interface) areas of the Gonarezhou National Park. Samples were screened for Brucellaantibodies using the Rose Bengal plate test and confirmed by the complement fixation test. Data were analysed by descriptive statistics and multivariate logistic regression modelling. In cattle, brucellosis seroprevalence from all areas was 16.7% (169/1011; 95% CI: 14.5-19.2%). The porous interface recorded a significantly (p=0.03) higher seroprevalence (19.5%; 95% CI: 16.1-23.4%) compared to the non-interface area (13.0%; 95% CI: 9.2-19.9%).The odds of Brucellaseropositivity increased progressively with parity of animals and were also three times higher (OR=3.0, 2.0

Bluetongue virus surveillance in the Islamic Republic of Mauritania: Is serotype 26 circulating among cattle and dromedaries?

In March 2013, EDTA-blood and serum samples were collected from 119 cattle and 159 dromedaries at the slaughterhouse of Nouakchott, the capital city of the Islamic Republic of Mauritania. Serum samples were screened for the presence of Bluetongue (BT) antibodies by competitive ELISA (cELISA). Positive samples were then tested by serum-neutralization (SN) to determine BTV serotype. RNA from blood samples was first tested by a genus-specific quantitative RT-PCR assay which is able to detect all 27 existing BTV serotypes (RT-qPCR1-27). Positive samples were further screened by a RT-qPCR assay which, instead, is able to detect the classical 24 BTV serotypes only (RT-qPCR1-24). Of the 278 serum samples tested, 177 (mean=63.7%; 95% CI: 57.9%-69.1%) resulted positive by cELISA. Of these, 69 were from cattle (mean=58.0%; 95% CI: 49.0%-66.5%) and 108 from dromedaries (mean=67.9%; 95% CI: 60.3%-74.7%). BTV-26 neutralizing antibodies were by far the most frequently found as they were detected in 146 animals with titres ranging from 1:10 to 1:80. Out of 278 blood samples, 25 (mean=9.0%; 95% CI: 6.2%-12.9%) were found positive for BTV by RT-qPCR1-27, 20 (mean=16.8%; 95% CI: 11.2%-24.6%) were from cattle and 5 (mean=3.1%; 95% CI: 1.4%-7.1%) from dromedaries. When tested by RT-qPCR1-24 the 25 BTV positive samples were negative. Unfortunately, no genetic information by molecular typing or by next generation sequencing has been obtained as for the very low levels of RNA in the blood samples.

Molecular detection of Nigerian field isolates of Mycoplasma mycoides subsp. mycoides as causative agents of contagious bovine pleuropneumonia.

Contagious bovine pleuropneumonia (CBPP) is a highly contagious respiratory disease affecting cattle and is widely distributed in the sub-Saharan Africa. The objective of this study was to detect Mycoplasma mycoides subspecies mycoides (Mmm) the causative agent of CBPP from 90 cattle at slaughter using polymerase chain reaction-Restriction fragment length polymorphism. In this study, 450 samples suggestive of CBPP in Maiduguri, Yola and Gombe township abattoirs were processed according to standard protocols. The isolation rate was found to be 3.33% and percentage of identification with PCR-RFLP yielded 1.56%. Subsequently, QIAxcel revealed molecular size of 574 bp for Mycoplasma mycoides subcluster. Further analysis of PCR amplicons with restriction digestion, confirmed the presence of Mmm 16 S rRNA of CAP 21 genomic region with molecular sizes of 180 bp and 380 bp. Thus, the 380 bp fragments delineated Mmm from Mycoplasma mycoides subsp. capri. Three isolates (BL5, BL6 and AL1) were from lungs and four from pleural fluids (APF2, APF8A, APF8B and APF9) were isolated and identified, while a vaccine strain T1/44 was re-detected along with the field isolates. No sample from Gombe had Mmm. In conclusion, the findings of this study have detected the presence of Mmm as causative agent of CBPP. Measures such as surveillance, quarantine and vaccination are hereby recommended for the control of CBPP in Nigeria.

Rift Valley Fever Virus among Wild Ruminants, Etosha National Park, Namibia, 2011.

After a May 2011 outbreak of Rift Valley fever among livestock northeast of Etosha National Park, Namibia, wild ruminants in the park were tested for the virus. Antibodies were detected in springbok, wildebeest, and black-faced impala, and viral RNA was detected in springbok. Seroprevalence was high, and immune response was long lasting.

African horse sickness outbreaks in Namibia from 2006 to 2013: clinical, pathological and molecular findings.

African horse sickness (AHS) is a vector­borne viral disease of equids, endemic in Sub­Saharan Africa. This article reports the clinic­pathological and laboratory findings observed in the framework of passive surveillance during the AHS outbreaks which occurred in Namibia between 2006 and 2013. This study was conducted in the framework of the collaboration among the Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise (Teramo, Italy), the Namibian Ministry of Agriculture Water and Forestry, and the Namibian National Veterinary Association. A total of 92 horses were investigated, showing different clinical form of AHS: peracute/acute (n = 43), sub­acute (n = 21) and mild AHS fever (n = 19). Clinical data were not available for 9 horses, because they were found dead. Pathological findings have been recorded for 35 horses. At necropsy, pulmonary and subcutaneous oedema, haemorrhages and enlargement of lymph nodes were mainly observed. Diagnosis was confirmed by laboratory testing, AHS virus (AHSV) was isolated from 50 horses and the identified serotypes were: 1, 2, 4, 6, 7, 8, and 9. The phylogenetic analysis of the S10 genome sequences segregated the Namibian AHSV strains in the same clusters of those circulating in South Africa in recent years. The description of AHS clinical, pathological, and laboratory features of AHS provided in this article is of value for differential diagnosis and control of AHS, especially in areas currently free from this disease.

Orbivirus detection from Culicoides collected on African horse sickness outbreaks in Namibia.

African horse sickness (AHS), a non-contagious infectious disease caused by a RNA virus in the Orbivirus genus within the Reoviridae family affecting all equids, is endemic in sub-Saharan Africa. The virus is transmitted by some species of biting midges in the genus Culicoides (Diptera: Ceratopogonidae). In April 2011, 8 Culicoides collections were performed in 6 districts of 4 regions of the Republic of Namibia (Africa), all within a 400 km radious from the capital Windhoek. Six farms - Khomas (Windhoek and Steinhausen), Erongo (Karibib and Omaruru), Otjozondjupa (Okahandja), and Omaheke (Gobabis) involved in the AHS outbreaks, were sampled. Overall 194,211 Culicoides were collected and identified. Culicoides imicola was largely the most abundant species at all farms (99.4%). A total of 18,687 parous and gravid Culicoides females were assayed for AHS virus (AHSV) by real time RT-PCR. Of the 248 assayed pools, 227 consisted of C. imicola, 13 of Culicoides pycnostictus and 5 of Schultzei complex. Only 1 pool each of Culicoides nivosus, Culicoides leucostictus, and Culicoides tropicalis was assayed. Of the 248 pools examined by real time RT-PCR, 81 tested positive for AHSV, all consisting of C. imicola collected at Omaruru, resulting in a field vector infection rate of 0.91%. No viable AHSV could be isolated from 88 of the tested pools (n = 1,463). However, bluetongue virus (BTV) serotype-1 and 10 were isolated from 3 of these pools, each consisting of 100 C. imicola collected at Windhoek. The present study confirms the relative low infection prevalence in field collected Culicoides and the strict relationship between the high abundance of C. imicola and outbreaks of AHSV.