The Incursion and Spread of Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4 Within South Africa.

The report of a mass die-off of white-winged terns (Chlidonias leucopterus) along the shores of Lake Victoria in Uganda in January 2017 was a warning that highly pathogenic avian influenza (HPAI) H5N8 clade 2.3.4.4 had entered the avian populations of the African Rift Valley. In early June 2017, Zimbabwe reported an outbreak of the virus in commercial breeder chickens near Harare, and on June 19, 2017, the first case of HPAI H5N8 was confirmed in a broiler breeder operation near Villiers, Mpumalanga Province, South Africa, representing the first ever notifiable influenza in gallinaceous poultry in South Africa. Forty viruses were isolated from wild birds, backyard hobby fowl, zoo collections, commercial chickens, and commercial ostriches over the course of the outbreak and full genomes were sequenced and compared to determine the epidemiologic events in the introduction and spread of clade 2.3.4.4 H5N8 across the country. We found that multiple virus variants were involved in the primary outbreaks in the north-central regions of South Africa, but that a single variant affected the southernmost regions of the continent. By November 2017 only two of the nine provinces in South Africa remained unaffected, and the layer chicken industry in Western Cape Province was all but decimated. Two distinct variants, suggesting independent introductions, were responsible for the first two index cases and were not directly related to the virus involved in the Zimbabwe outbreak. The role of wild birds in the incursion and spread was demonstrated by shared recent common ancestors with H5N8 viruses from West Africa and earlier South African aquatic bird low pathogenicity avian influenza viruses. Improved wild bird surveillance will play a more critical role in the future as an early warning system.

Incursión y propagación del virus de la influenza aviar altamente patógena H5N8 clado 2.3.4.4 en Sudáfrica. El informe de una muerte masiva de fumareles aliblancos (Chlidonias leucopterus) a lo largo de las orillas del lago Victoria en Uganda en enero del 2017 fue una advertencia de que la influenza aviar de alta patogenicidad (HPAI) H5N8, clado 2.3.4.4 había ingresado en las poblaciones de aves del Valle del Rift Africano. A principios de junio del 2017, Zimbabwe reportó un brote del virus en pollos reproductores comerciales cerca de Harare, y el 19 de junio del 2017, el primer caso de influenza aviar de alta patogenicidad H5N8 se confirmó en una operación de pollos de engorde en la provincia de Mpumalanga cerca de Villiers, Sudáfrica, que representa el primer caso de influenza notificable en aves gallináceas en Sudáfrica. Se aislaron cuarenta virus de aves silvestres, aves de traspatio, colecciones de zoológicos, pollos comerciales y avestruces comerciales durante el transcurso del brote. Se secuenciaron los genomas completos y se compararon para determinar los eventos epidemiológicos en la introducción y propagación del subtipo H5N8 clado 2.3.4.4 a través del país. Se encontró que múltiples variantes del virus estaban involucradas en los brotes primarios en las regiones centro y norte de Sudáfrica, pero que una sola variante afectaba a las regiones más al sur del continente. En noviembre de 2017, solo dos de las nueve provincias de Sudáfrica permanecían sin afectarse y la industria de pollos en la Provincia de Cabo Occidental resultó casi diezmada. Dos variantes distintas, que sugieren introducciones independientes, fueron responsables de los dos primeros casos índices y no estuvieron directamente relacionados con el virus involucrado en el brote de Zimbabwe. El papel de las aves silvestres en la incursión y diseminación fue demostrado por los ancestros comunes compartidos con los virus H5N8 de África Occidental y los virus de la influenza aviar de baja patogenicidad de aves acuáticas de Sudáfrica detectados anteriormente. La mejora de la vigilancia de aves silvestres jugará un papel más crítico en el futuro como un sistema de alerta temprana.

Seminal transmission of lumpy skin disease virus in heifers.

It is known that lumpy skin disease virus (LSDV) can be shed in bull semen following infection and also that artificial insemination (AI) poses a biosecurity risk. However, it is not known whether the use of LSDV infected semen in AI poses a biosecurity risk. The aim of this study was to investigate whether LSDV, transmitted through semen, can infect cows and their embryos. Two controlled trials were performed simultaneously. Eleven young beef heifers, naïve to LSDV, were synchronized using an OvSynch protocol and inseminated on Day 0 with fresh semen spiked with a field strain of LSDV on day 0. Six of the heifers were superovulated on Day 1 using pregnant mare serum gonadotropin, and embryos were flushed from these heifers on Day 6. Blood and serum samples were collected from Day 4 until Day 27 to determine the presence of LSDV by PCR and virus isolation, and the presence of antibodies against LSDV by SNT. The first clinical signs of LSD were noticed on Day 10, followed by severe generalized LSD in three heifers and mild LSD in two more heifers. Two heifers were humanely euthanized due to severe unresponsive stranguria. LSDV was detected by PCR, virus isolation or electron microscopy in blood, embryos and organs of experimentally infected animals; and eight heifers had seroconverted by Day 27. Two control animals were not affected. This is the first report of experimental seminal transmission of LSDV in cattle.

Detection of lumpy skin disease virus in saliva of ticks fed on lumpy skin disease virus-infected cattle.

Lumpy skin disease is an economically important disease of cattle that is caused by the lumpy skin disease virus (LSDV), which belongs to the genus Capripoxvirus. It is endemic in Africa and outbreaks have also been reported in the Middle-East. Transmission has mostly been associated with blood-feeding insects but recently, the authors have demonstrated mechanical transmission by Rhipicephalus appendiculatus as well as mechanical/intrastadial and transstadial transmission by Amblyomma hebraeum. Saliva is the medium of transmission of pathogens transmitted by biting arthropods and, simultaneously, it potentiates infection in the vertebrate host. This study aimed to detect LSDV in saliva of A. hebraeum and R. appendiculatus adult ticks fed, as nymphs or as adults, on LSDV-infected animals, thereby also demonstrating transstadial or mechanical/intrastadial passage of the virus in these ticks. Saliva samples were tested for LSDV by real-time PCR and virus isolation. Supernatants obtained from virus isolation were further tested by real-time PCR to confirm that the cytopathic effects observed were due to LSDV. Lumpy skin disease virus was detected, for the first time, in saliva samples of both A. hebraeum and R. appendiculatus ticks. At the same time, mechanical/intrastadial and transstadial passage of the virus was demonstrated and confirmed in R. appendiculatus and A. hebraeum.