Efficacy of current vaccines against recently isolated foot and mouth disease virus type A South America (Venezuela) in Egypt 2022

Foot and mouth disease is a highly contagious viral disease that poses a significant economic threat to cloven-hoofed animals, including cattle and sheep. The emergence of a novel foot and mouth disease virus-A isolate, FMDV-A-Egy-AHRI-RL385-Ven-2022, in Egypt in 2022 has raised concerns about its potential impact on existing vaccination programs. Given that vaccination is a key strategy for foot and mouth disease virus control, the present study was aimed to assess the cross-protective efficacy of both local and imported inactivated vaccines against this new threat. Through challenge experiments and serum neutralization tests, we observed limited effectiveness of both vaccine types. The calculated r1-values at 28 days post-vaccination indicated a minimal immune response to FMDV-A-Egy-AHRI-RL385-Ven-2022 (0.176 and 0.175 for local and imported vaccines, respectively). Challenge experiments further confirmed these findings, revealing 0percent protection from the local vaccine and only 20percent rotection from imported vaccines by day 7 post-challenge. These results underscore the urgent need to update existing foot and mouth disease virus vaccines in Egypt by incorporating the newly circulating FMDV-A-Egy-AHRI-RL385-Ven-2022 strain. This proactive measure is crucial to prevent future outbreaks and ensure effective disease control(AU)

La fiebre aftosa es una enfermedad vírica muy contagiosa que supone una importante amenaza económica para los animales biungulados, entre ellos el ganado vacuno y ovino. La aparición de un nuevo aislado del virus A de la fiebre aftosa, el FMDV-A-Egy-AHRI-RL385-Ven-2022, en Egipto en 2022 ha suscitado preocupación por su posible impacto en los programas de vacunación existentes. Dado que la vacunación es una estrategia clave para el control del virus de la fiebre aftosa, el objetivo del presente estudio fue evaluar la eficacia protectora cruzada de las vacunas inactivadas locales e importadas frente a esta nueva amenaza. Mediante experimentos de desafío y pruebas de seroneutralización, observamos una eficacia limitada de ambos tipos de vacuna. Los valores r1 calculados a los 28 días posvacunación indicaron una respuesta inmunitaria mínima frente a FMDV-A-Egy-AHRI-RL385-Ven-2022 (0,176 y 0,175 para las vacunas local e importada, respectivamente). Los experimentos de provocación confirmaron aún más estos resultados, revelando un 0 por ciento de protección de la vacuna local y sólo un 20 por ciento de protección de las vacunas importadas al séptimo día después de la provocación. Estos resultados subrayan la urgente necesidad de actualizar las vacunas existentes contra el virus de la fiebre aftosa en Egipto incorporando la nueva cepa circulante FMDV-A-Egy-AHRI-RL385-Ven-2022. Esta medida proactiva es crucial para prevenir futuros brotes y garantizar un control eficaz de la enfermedad(AU)

Evaluación de emergencia de una vacuna existente contra el virus de la fiebre aftosa tipo SAT2, aislado recientemente en Egipto en el 2018 / Emergency evaluation for existing vaccine against recently isolated Foot and mouth disease virus type SAT2 in Egypt 2018

El virus de la fiebre aftosa es un patógeno altamente infeccioso y contagioso. Recientemente, el topotipo VII, linaje Lib-12 del serotipo SAT2 se describió en brotes en Egipto durante 2018. La vacunación es una forma eficaz de controlar y combatir los brotes del virus de la fiebre aftosa, especialmente en áreas endémicas como Egipto. El presente estudio tuvo como objetivo evaluar la eficacia de la vacuna contra la fiebre aftosa que se produce actualmente, frente a la cepa de campo recientemente aislada del virus de la fiebre aftosa SAT2 topotipo VII, linaje Lib-12 (SAT2 Libia), mediante la aplicación de estudios in vitro e in vivo. Se inocularon en terneros, dos lotes de la vacuna actual contra el virus de la fiebre aftosa. A los 28 días posteriores a la vacunación, se recolectaron muestras de suero y se analizaron contra el virus de la fiebre aftosa SAT2 Libia adaptado a cultivo de tejidos y SAT2/EGY/2/2012 utilizando una prueba de neutralización viral para determinar la relación serológica (valor r1). El ensayo de reto en terneros vacunados se llevó a cabo empleando una cepa virulenta de la fiebre aftosa SAT2 Libia. Se encontró que los títulos de anticuerpos neutralizantes inducidos por los dos lotes de vacuna (1 y 2) y los de animales no vacunados, fueron 0,48, 0,39 y 0,15 log10 DICT50/mL, respectivamente, mientras que la prueba reveló valores de protección de 20 por ciento, 0 por ciento y 0 por ciento, respectivamente. Además, los valores de r1 fueron 0,195 y 0,186 para los lotes de vacuna (1 y 2), respectivamente. Se llegó a la conclusión de que los lotes de vacunas locales comerciales inactivadas disponibles actualmente (SAT2 SAT2/EGY/2/2012) no protegen a los terneros contra el virus circulante de la fiebre aftosa SAT2 topotipo VII, linaje Lib-12 que se aisló recientemente, por lo que es recomendable actualizar las vacunas existentes con la cepa aislada actualmente(AU)

Foot and mouth disease virus is a highly infectious and contagious pathogen. Recently the topotype VII, Lib‐12 lineage of serotype SAT2 was reported through outbreaks in Egypt during 2018. Vaccination is an effective way to control and combat the foot and mouth disease virus outbreaks especially in endemic areas like Egypt. The present study was aimed to evaluate the efficacy of the current produced foot and mouth disease vaccine, against the recently isolated field strain foot and mouth disease virus SAT2 topotype VII, Lib-12 lineage (SAT2 Libya), by applying in vitro and in vivo studies. Two batches of the current foot and mouth disease virus vaccine were inoculated in calves. At the 28th day post-vaccination serum samples were collected and tested against tissue culture adapted foot and mouth disease virus SAT2 Libya and SAT2/EGY/2/2012 using virus neutralization test to determine serological relationship (r1-value). The challenge test for vaccinated calves was carried out against the virulent foot and mouth disease virus SAT2 Libya. It was found that neutralizing antibody titers induced by the two vaccine batches (1 and 2) and those in unvaccinated animals were 0.48, 0.39 and 0.15 log10 TCID50/mL, respectively, while the challenge revealed protection values of 20 percent, 0 percent and 0 percent, respectively. Furthermore, the r1 values were 0.195 and 0.186 for vaccine batches (1 and 2), respectively. It was concluded that the available local commercial inactivated foot and mouth disease virus vaccine batches (SAT2 SAT2/EGY/2/2012) are unable to protect calves against the current circulating foot and mouth disease virus field isolate SAT2 topotype VII, Lib-12 lineage, thus it is highly recommended to update the existing vaccines with the present isolated strain(AU)

Evaluation of infectivity and transmission of different Asian foot-and-mouth disease viruses in swine

Most isolates of foot-and-mouth disease virus (FMDV) display a broad host range. Since the late 1990s, the genetic lineage of PanAsia topotype FMDV serotype O has caused epidemics in the Far East, Africa, the United Kingdom, France, the Netherlands, and numerous other countries throughout Europe and Asia. In contrast, there are several FMDV isolates that exhibit a more restricted host range. A Cathay topotype isolate of FMDV serotype O from the 1997 epizootic in Taiwan (O/TAW/97) demonstrated restricted host specificity, only infecting swine. Methods used to evaluate infectivity and pathogenicity of FMDV isolates in cattle are well-documented, but there has been less progress studying transmission and pathogenicity of FMDV isolates in pigs. In previous studies designed to examine pathogenicity, various chimeric viruses derived from O/TAW/97 were intradermally inoculated in the heel bulb of pigs. Subsequent quantitative scoring of disease and evaluation of virus released into nasal secretions and blood was assessed. Here we prove the usefulness of this method in direct and contact inoculated pigs to evaluate infectivity, pathogenicity and transmission of different Asian FMDV isolates. Virus strains within the Cathay topotype were highly virulent in swine producing a synchronous disease in inoculated animals and were efficiently spread to in-contact naive pigs, while virus strains from the PanAsia topotype displayed more heterogeneous properties.

Fiebre aftosa en seres humanos: Un caso en Chile / Foot and mouth disease in human beings: A human case in Chile

Foot and mouth disease (FMD) of cattle can cause a significant economic burden and is thus for one of the most feared of cattle disease. FMD is endemic in South America, Africa, Asia and parts of Europe and it is characterized by vesicles in different locations, mainly mouth, feet and teats leading to severe animal weakness. Currently most countries refuse to import livestock and livestock products from FMD areas. North and Central America are currently free of FMD and Chile is free of FMD from 1987. Approximately 40 cases of human infection with FMD virus have been reported, mostly in Europe, and confirmed by virus isolation and the detection of a specific immune response. We discuss the case of a human infection with FMD virus occurred in Chile in 1961 and other relevant cases reported. FMD does not currently present a threat to public health. Even though the FMD virus has the potential to mutate rapidly and emerge as a significant human zoonosis; the rarity of the disease in humans despite a long history of close contact with FMD infected animals suggests that the risk is highly improbable. Then FMD should not be managed as a zoonosis.

La fiebre aftosa se presenta en los biungulados, siendo el cerdo el animal más susceptible. La infección de estos animales lleva a cuantiosas pérdidas económicas por disminución de la producción de leche o carne. En la actualidad esta enfermedad constituye una plaga que causa serios trastornos en el comercio pecuario mundial y se la considera como una enfermedad trans-fronteriza. Chile está libre se esta enfermedad desde 1987. La fiebre aftosa en seres humanos ha sido descrita principalmente en Europa, habiéndose confirmado, aproximadamente, unos 40 casos por aislamiento viral y detección de anticuerpos específicos. Se describen los principales casos de fiebre aftosa en seres humanos descritos en la literatura científica, incluyendo un caso ocurrido en Chile en 1961. Se discute la importancia de esta enfermedad en seres humanos y se cuestiona el planteamiento de que es una zoonosis.

Estudio de la performance del modelo Covello-Merkhofer en la medición del riesgo en planes de vacunación antiaftosa / Performance study of the Covello-Merkhofer model in the treatment of risk in anti-footprint vaccination plans

La cíclica y masiva movilización de terneros puede determinar la recurrencia y persistencia de fiebre aftosa. Por ello, en Sudamérica se promueven esquemas de vacunación en función de la dinámica ganadera. Para evaluar mejor estos esquemas se desarrolló y aplicó un modelo estadístico de cuantificación de riesgos para asistir en la evaluación de planes de vacunación sistemática contra la fiebre aftosa de bovinos. El modelo utiliza información sobre la epidemiología de la fiebre aftosa; de la dinámica poblacional y de vacunación recolectada en un período llamado Ventana de Observación/Estimación y la proyecta hacia una fecha futura ubicada en un período llamado Ventana de Predicción en donde se obtuvo un predictor de la probabilidad de contacto entre terneros no vacunados y bovinos residualmente infectados por el virus de la fiebre aftosa. El modelo utiliza estimación de parámetros obtenidos de la opinión experta; de evidencias empíricas; o de la conjugación de ambos mediante estimadores bayesianos de las distribuciones Beta y Dirichlet. El modelo se aplicó a datos de Argentina mediante simulación de Monte Carlo, permitiendo identificar diferencias significativas al 5% entre los efectos de tres alternativas de vacunación comparadas mediante el método de Bonferroni.(AU)

The recurrence and persistence of fmd could be the consequence of cyclic and massive transportation of calves. For this reason, vaccination schemes related to livestock dynamic are promoted in South America. To improve the evaluation of vaccination schemes a quantitative stochastic risk assessment model was developed and applied in order to aid in the evaluation of strategies of systematic vaccination of cattle against fmd. The model uses information about fmd epidemiology and about population and vaccination dynamics. The information is collected during a period of time called Observation/Estimation Window and projected to a later time called Prediction Window where a predictor of the probability of contact between non-vaccinated calves with residually fmd infected cattle is obtained. Estimates of the parameters of the model are obtained from: expert opinion; empirical evidence or the conjugation of both by means of Bayesian estimators of the Beta and Dirichlet distributions. Applied to data of Argentina, through Monte Carlo simulation, the model allowed the identification of significant statistical differences among the effects of three different vaccination alternatives compared by Bonferroni test.(AU)

Identification and antigenic site analysis of foot-and-mouth disease virus from pigs and cattle in Korea

From May to June 2002, a total of 16 foot-and mouth disease (FMD) outbreaks due to the serotype O virus, Pan Asia strain, were recorded in Korea. The viruses were identified by antigen ELISA, RT-PCR and sequence analysis. The overall nucleotide sequence divergence of the VP1 region among the 4 isolates in 2002 was 0 to 1.4%, but between O/SKR/2002 and O/SKR/2000 isolates was 1.9-4.9%. Phylogenetic analysis with the some known strains from East Asian countries showed that the 4 Korean isolates in 2002 formed one distinct cluster, which different from clusters of Korean isolates in 2000, with in the same lineage of the ME-SA topotype strains. Deduced amino acid sequences around neutralizable antigenic site on VP1 site of O/SKR/2002 isolates were aligned and compared with other strains. At the antigenic site 1, the replacements of the critical amino acid residues at position 144 from V to L and at position 152 from A to T were observed in O/SKR/2002 viruses. For antigenic site 2 and 4, there were not significant variations in general. At the antigenic site 3, the substitutions of amino acid residues were present at positions 54 and 56 in O/SKR/2002 isolates and an alternative residue I at position 54 are observed only at the sequence of O/SKR/AS/2002 (cow) virus. And the substitution (L-->P) of significant residue at position 144 was detected at the amino acid sequence of the O/SKR/2002 (cow) virus.

A febre aftosa no Brasil, 1960-2002 / The foot-and-mouth disease in Brazil, 1960-2002

A análise da ocorrência da febre aftosa no Brasil indicou a endemicidade da doença até os anos 80, quando houve redução de focos após a identificação e controle das áreas endêmicas e uso da vacina de qualidade. O vírus tipo A foi responsável pelas principais epidemias. O tipo C foi o de menor incidência entre os três tipos diagnosticados no país (O, A e C). O programa de erradicação, implantado em 1992, com estratégias diferenciadas, de acordo com o sistema de produção e participação de representantes do agronegócio, resultou na eliminação dos focos a partir de 2001. O relato da febre aftosa no Brasil desde a década de 60 alerta para a importância de se conhecer o histórico da doença e elaborar a política pública em saúde animal e os planos de contingência no país livre da febre aftosa.

Dinâmica espacial da febre aftosa em bovinos: um modelo matemático / Spatial dynamic on foot and mouth disease in bovines: a mathematical model

Objetivo: Propöe um modelo matemático que simula a dinâmica espacial da febre aftosa em bovinos e que permte estimar a velocidade mínima de propagaçäo da mesma, bem como a extensäo de uma zona de bloqueio vacinal que impede a sua disseminaçäo, que foi validado anteriormente. Método: Utilizou um sistema de equaçöes diferenciais que representa a história natural da doença em bovinos incorporando a dimensäo espacial através da utilizaçäo da equaçäo de difusäo. As determinaçöes dos valores das taxas de natalidade, de descarte, do coeficiente de difusäo, do coeficiente de transmissibilidade e da capacidade suporte do meio foram realizadas com base nos dados populacionais do rebanho bovino do estado. Os valores das taxas de perda de imunidade, de mortalidade pela doença e de recuperaçäo foram obtidos na literatura. Resultados e conclusöes: A extensäo da zona de bloqueio vacinal depende da densidade de suscetíveis presentes nessa área e pode ser determinada com base na probabilidade de que um animal infectado entre em contato com um animal suscetível, o que significa assumir risco conhecido de que isso aconteça. Considerando-se a presença de apenas 2,28 por cento de suscetíveis nessa zona, a probabilidade de contato entre animais suscetíveis e infectados, para um valor de p=0,60 animal/Km, varia de 0,025 a 0,0001 para uma extensäo variando de 10 a 20 Km, respectivamente. O modelo, considerado válido através da comparaçäo do resultado da simulaçäo em duas dimensöes com os dados reais de uma epidemia de febre aftosa ocorrida no ano de 1990 no Estado de Santa Catarina, foi capaz de simular adequadamente a difusäo espacial da epidemia de febre aftosa ocorrida anteriormente na mesma área

Avaliaçäo do sistema de vigilância epidemiológica para a febre aftosa em Goiás no período 1980-1990 / Avaliation of epidemiologic surveillance service to the foot-and-mouth disease in Brazil from 1980 to 1990

Analisou-se o sistema de vigilância em Goiás, de 1980 a 1990, tendo como referência a febre aftosa. Avaliaram-se os aspectos origem das notificaçöes, tipo de diagnóstico, duraçäo dos focos, intervalo entre início e notificaçäo dos focos e primeira visita do veterinário. Verificaram-se tendência decrescente das notificaçöes, predomínio dos registros realizados pelos proprietários, baixo percentual de diagnóstico laboratorial e elevado intervalo entre o início dos focos, sua notificaçäo e assistência. Discutiu-se o modelo avaliado e sugeriu-se a incorporaçäo de outros indicadores (bioprodutivos, econômicos e demográficos) nos sistemas vigentes

Reavaliaçäo das áreas endêmicas primárias de febre aftosa em Minas Gerais / Reavaliation of primary ecosystems of foot-and-mouth disease in Minas Gerais

Objetivando-se reavaliar as áreas endêmicas primárias de febre aftosa em Minas Gerais, partiu-se do pressuposto que as formas de organizaçäo da produçäo pecuária säo determinantes na configuraçäo dos ecossistemas da enfermidade. A caracterizaçäo dos principais componentes estruturais do ecossistema regional, visando estabelecer relaçöes entre tais componentes e o comportamento epidemiológico da enfermidade, foi realizada através da análise de indicadores econômicos, demográficos e ecológicos. Constatou-se que a regiäo endêmica primária apresenta três conglomerados distintos, sendo o primeiro formado pela microrregiäo homogênea de Chapadöes do Paracatu, classificada como regiäo extrativa extensiva de cria. O segundo conglomerado abrange as microrregiöes homogêneas de Pastoril de Almenara, Pastoril de Pedra Azul e Teófilo Otoni, caracterizadas como áreas pré-empresariais de cria. O último conglomerado é composto pela microrregiäo de Pastoril de Nanuque, definida como área de ciclo completo para corte, microrregiäo homogênea de Mantena e parte da microrregiäo de Mata de Caratinga, ambas sinalizando para formas familiares de ciclo completo. Reafirmou-se que as áreas endêmicas primárias mantém o vírus de forma contínua e persistente em funçäo da dinâmica populacional bovinas nestas regiöes