A serological survey of African horse sickness in Botswana

A retrospective serological survey of African horse sickness (AHS) in Botswana covering a 10-year period (1995-2004) is reported. The survey involved horses showing clinical symptoms of the disease; the horses had not been vaccinated against AHS. Over the period surveyed, serological evidence suggestive of infection with AHS virus (AHSV) was found in 99 clinical cases out of which 41.4% (41/99) cases were found during the 1st half (1995-1999) and 58.6 % (58/99) cases were found in the 2nd half of the survey period (2000-2004). These serological findings are discussed in relation to AHSV serotypes isolated from diseased horses in Botswana before and during the period of this serological survey.     

Epidemiological investigations of contagious caprine pleuropneumonia in selected districts of Borana zone,Southern Oromia,Ethiopia

Tropical Animal Health and Production - From November 2016 to April 2017, a cross-sectional study to determine the sero-prevalence of contagious caprine pleuropneumonia (CCPP) and to investigate...     

African horse sickness in Spain.

The aetiology, pathogenesis and epizootiology of African horse sickness (AHS) are reviewed with special reference to recent outbreaks in the Iberian peninsula. AHS is a highly fatal insect-borne viral disease of Equidae. It is caused by an Orbivirus (family Reoviridae) and nine serotypes are recognised. Outbreaks occurred in central Spain in 1987 and in southern regions of the Iberian peninsula in 1988, 1989 and 1990. All were associated with serotype 4 of the virus, whereas other occurrences of AHS outside Africa have all been caused by serotype 9. The clinical picture in the outbreaks was mainly of the acute (pulmonary) form except in 1988 when the subacute (cardiac) form of disease predominated. Several hundred horses died or were destroyed as a result of the outbreaks. Further spread was contained by a combination of slaughter of sick animals, movement controls, and vaccination which was extended over an increasingly wide area in successive years. The 1987 outbreak is believed to be associated with infected zebras imported from Africa. Possible explanations for the recurrence of disease in Spain in successive years are considered to include (a) the climatic conditions in Southern Spain, which could permit continuous vector activity, (b) the relative clinical resistance of mules and donkeys, which may permit subclinical circulation of the virus, (c) incomplete population immunity among horses due to possible gaps in the vaccination strategy.     

African horse sickness in naturally infected,immunised horses

To determine whether subclinical cases, together with clinical cases, of African horse sickness (AHS) occur in immunised horses in field conditions, whole blood samples were collected and rectal temperatures recorded weekly from 50 Nooitgedacht ponies resident in open camps at the Faculty of Veterinary Science, University of Pretoria, Onderstepoort, during 2008–2010. The samples were tested for the presence of African horse sickness virus (AHSV) RNA by a recently developed real‐time RT‐PCR. It was shown that 16% of immunised horses in an AHS endemic area were infected with AHSV over a 2 year period, with half of these (8%) being subclinically infected. The potential impact of such cases on the epidemiology of AHS warrants further investigation.     

非洲马瘟病毒分子生物学研究进展

非洲马瘟病毒属呼肠病毒科环状病毒属,有9个血清型,是一种有10个节段(L1~L3,M4~M6,S7~S10)的双链RNA病毒,编码10个蛋白(VP1~VP7和NS1,NS2,NS3/NS3A)。VP2蛋白在病毒的各蛋白中变异率最大,有15个抗原位点,是病毒的血清型特异性抗原,能与病毒的中和抗体发生反应;VP7蛋白在病毒的各蛋白中最保守,是病毒的血清群特异性抗原。NS1蛋白在感染细胞中形成病毒特异性微管结构;NS3蛋白在病毒各蛋白中变异率位居第二,系统进化分析将NS3分成3个进化群(α,β和γ)。该病毒的分子生物学诊断技术主要有RT-PCR和核酸探针技术。     

Epizootiology and vectors of African horse sickness virus

African horse sickness (AHS) virus causes a non-contagious, infectious, arthropod-borne disease of equines and is enzootic in sub-Saharan Africa. The major vectors are species of Culicoides but mosquitoes and ticks may be involved. Periodically the virus makes excurisons beyond its enzootic zones but until recently has not been able to maintain itself outside these areas for more than 2–3 consecutive years. This is probably due to a number of factors including the absence of a long term vertebrate reservoir, the prevalence and seasonal incidence of the vectors and the efficiency of control measures. The recent AHS epizootics in Iberia and North Africa seem to have established a new pattern in AHS virus persistence. This is probably linked to the continuous presence of adult C. imicola in the area. Culicoides imicola is basically an Afro-Asiatic insect and prefers warm climates. Therefore its continuous adult presence in parts of Iberia may be due to some recent moderation of the climate in these areas.     

African horse sickness in Zimbabwe: 1972 to 1981

Summary During the nine years from October 1972 to September 1981 African horse sickness (AHS) virus was isolated from 23 suspected cases of the disease in Zimbabwe and complement fixation antibody titres indicative of recent infection were detected in a further 49 horses. The 23 isolations belonged to seven of the nine known serotypes of AHS virus. In response to a questionnaire in 1980 the owners of 20% (1,654/8,000) of the horses in Zimbabwe indicated that they had recorded 207 cases of clinically diagnosed AHS with 107 deaths from 1975 to 1980. Fifty-six cases with 50 deaths had occurred in foals and many of the other cases occurred in horses which had been vaccinated. It was concluded that the immunity induced by vaccine and maternal immunity warranted further investigation.

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Peste Equina Africana En Zimbabwe: 1972–1981

Resumen Se aisló virus de peste equina africana de 23 casos sospechosos de la enfermedad en Zimbabwe, detectándose infecciones recientes mediante fijación de complemento, en 49 caballos más. Los 23 aislamientos pertenecían a siete de los nueve serotipos conocidos de la enfermedad. Veinte por ciento de propietarios de equinos que respondieron a una encuesta formulada en 1980 (1654/8000), indicaron que habían reconocido 207 casos de la enfermedad, diagnosticados clínicamente, entre 1975 y 1980. Cincuenta y seis casos con 50 muertes ocurrieron en potros y los demás en caballos que habían sido vacunados. Se concluye, que se necesitan más investigaciones en cuanto a la inmunidad materna y aquella inducida por la vacuna ahora en al mercado.

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La Peste Equine Au Zimbabwe: 1972 À 1981

Résumé Durant les neuf ans allant d'octobre 1972 à septembre 1981, le virus de la peste équine a été isolé à partir de 23 cas de maladie suspectée au Zimbabwé, et par la fixation du complément, des titres indicateurs d'une infection récente ont été détectés chez 49 autres chevaux. Les souches isolées appartenant à sept des neuf sérotypes connus du virus. En réponse à un questionnaire de 1980, les propriètaires de 20% (1654/8000) des chevaux du Zimbabwé ont indiqué qu'ils ont recontré 207 cas de peste équine diagnostiquée cliniquement, avec 107 mortalités entre 1975 et 1980. Cinquante-cinq cas, dont 50 mortaliltés, se sont produits chez des poulains, et beaucoup des autres cas ont été observés chez des chevaux qui avaient été vaccinés. Il est conclu que l'immunité engendrée par le vaccin, ainsi que l'immunité maternelle, nécessite d'autres recherches.

     

Re-emergence of bluetongue, African horse sickness, and other Orbivirus diseases

Arthropod-transmitted viruses (Arboviruses) are important causes of disease in humans and animals, and it is proposed that climate change will increase the distribution and severity of arboviral diseases. Orbiviruses are the cause of important and apparently emerging arboviral diseases of livestock, including bluetongue virus (BTV), African horse sickness virus (AHSV), equine encephalosis virus (EEV), and epizootic hemorrhagic disease virus (EHDV) that are all transmitted by haematophagous Culicoides insects. Recent changes in the global distribution and nature of BTV infection have been especially dramatic, with spread of multiple serotypes of the virus throughout extensive portions of Europe and invasion of the south-eastern USA with previously exotic virus serotypes. Although climate change has been incriminated in the emergence of BTV infection of ungulates, the precise role of anthropogenic factors and the like is less certain. Similarly, although there have been somewhat less dramatic recent alterations in the distribution of EHDV, AHSV, and EEV, it is not yet clear what the future holds in terms of these diseases, nor of other potentially important but poorly characterized Orbiviruses such as Peruvian horse sickness virus.     

Sero-prevalence of bovine brucellosis and its risk factors in Jimma zone of Oromia Region,South-western Ethiopia

A cross sectional sero-prevalence study was conducted on 1,595 cattle in Jimma zone, Ethiopia to investigate the status of bovine brucellosis and identify potential risk factors. Sera samples were analyzed using Rose Bengal Plate Test (RBPT) and Complement Fixation Test (CFT). The overall individual and herd level sero-prevalences were 3.1% (n = 1,595) and 15.0% (n = 227), respectively. The sero-prevalence of bovine brucellosis at individual animal level was significantly higher in non-pregnant (11.18%) than pregnant (2.77%) and lactating (22.35%) than non-lactating animals (2.46%). Moreover, significantly higher sero-prevalence was observed in herds of larger sizes. Individual animal sero-prevalence was also positively associated with the occurrence of abortion (26.98 and 1.54% in those with and without previous history of abortion, respectively). Generally, the sero-prevalence of bovine brucellosis found in Jimma area was not high and the sero-prevalence was closely associated with some of the risk factors considered at individual animal and herd level.     

Serological survey of small ruminants in 4 districts of Niger]

In 1990, a serosurvey on 1,474 small ruminants was conducted in four districts of Niger (Maradi, Zinder, Diffa and Dosso). The epidemiology and seroprevalence of eight diseases were studied: Brucella melitensis and B. ovis brucellosis, chlamydiosis, coxiellosis, contagious caprine pleuropneumonia, type A pasteurellosis, peste des petits ruminants, Rift Valley fever, Crimée-Congo haemorragic fever. The main health problem for the development of small ruminants farming, seems to be both pasteurellosis and peste des petits ruminants.