RESUMO
This study investigates the historical temporal trend and geographical distribution of the foot-and-mouth disease virus (FMDv) serotype C in South America; discussing the findings within the context of the actions and strategies carried out for the elimination of foot-and-mouth disease (FMD). This is the first time that such a comprehensive historical compilation has been carried out in the Region; hence, the study is intended as a reference and source of evidence about the presence/absence of FMDv serotype C in South America. Data on the occurrence of FMD were sourced from the Weekly Epidemiological Reports submitted by the countries to Pan American Foot-and-Mouth Disease Center (PANAFTOSA-PAHO/WHO) since 1972, and complemented with other sources of information from the 1968-1971 period. The temporal distribution was examined with local weighted regression (LOESS) to identify two temporal trends, that is, "smoothed" and "over-adjusted", utilising the time-series with the total number of cases per year, at Regional level. Thereafter the outbreaks were aggregated by decades and mapped by the first subnational administrative level. As a result, two major peaks of occurrence were identified, one in the 70s, with up to 1,193 outbreaks, and another in the 80s, with 380. Overall, the investigations show a clear regressive trend in the occurrence of serotype C, with a reduction in the number of outbreaks over-time, and with the subsequent reduction of affected locations. This study illustrates the contrast between the very limited presence over the last 20 years - with only one event in 2004 - and the epidemic situation in the 1970s and 1980s, and suggests that serotype C of FMDv is no longer present in the Region.
Assuntos
Búfalos , Doenças dos Bovinos , Vírus da Febre Aftosa/fisiologia , Febre Aftosa , Doenças das Cabras , Doenças dos Ovinos , Animais , Bovinos , Doenças dos Bovinos/diagnóstico , Doenças dos Bovinos/prevenção & controle , Doenças dos Bovinos/transmissão , Doenças dos Bovinos/virologia , Febre Aftosa/diagnóstico , Febre Aftosa/prevenção & controle , Febre Aftosa/transmissão , Febre Aftosa/virologia , Vírus da Febre Aftosa/genética , Doenças das Cabras/diagnóstico , Doenças das Cabras/prevenção & controle , Doenças das Cabras/transmissão , Doenças das Cabras/virologia , Cabras , Sorogrupo , Ovinos , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/prevenção & controle , Doenças dos Ovinos/transmissão , Doenças dos Ovinos/virologia , América do Sul , Análise Espaço-TemporalRESUMO
The control of foot-and-mouth disease (FMD) in vaccinated populations relies upon surveillance activities such as clinical inspections (CI) and serological monitoring. New evidence to refine current surveillance guidelines has been provided by evaluating (1) the diagnostic performance of CI and serological tests for detection of FMD virus (FMDV) non-structural proteins (NSP), and (2) the within-herd transmission of the virus in partially immune cattle. Data came from 23 affected herds during an epidemic of FMDV type O in Bolivia, in 2007. All cattle (n=957) in these herds were clinically inspected and serum samples were collected one month after the last animal with clinical signs was detected. Samples were tested for the presence of antibodies against NSP using the PANAFTOSA 3ABC-ELISA test and a subset of samples were tested using the enzyme-linked immunoelectrotransfer blot assay (EITB). Data from clinical and serological diagnoses were analysed using a Bayesian model. The sensitivity Se and specificity Sp of the tests, as well as the prevalence and the within-herd reproduction ratio R of FMDV were estimated. In addition, risk factors for infection were identified. The Se of CI, the 3ABC-ELISA and the EITB tests were estimated to be 0.30, 0.88 and 0.96 respectively. The estimated Sp, in the same order, were 0.88, 0.93 and 0.97. The within-herd prevalence of infected animals ranged from 0.04 to 0.91 and R ranged from 1.02 to 2.68. It was observed that cattle coming from areas with high vaccination coverage had a lower risk of becoming infected than home-bred cattle from the affected herds, where vaccination coverage was thought to be low. Although these estimates come from herds kept under specific conditions, they provide a reference for future surveillance design and can inform simulation models for surveillance and control of FMD in similar cattle populations.
Assuntos
Anticorpos Antivirais/sangue , Doenças dos Bovinos/diagnóstico , Febre Aftosa/diagnóstico , Vacinação/veterinária , Animais , Teorema de Bayes , Bolívia/epidemiologia , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/transmissão , Surtos de Doenças/veterinária , Ensaio de Imunoadsorção Enzimática/veterinária , Monitoramento Epidemiológico/veterinária , Feminino , Febre Aftosa/epidemiologia , Febre Aftosa/transmissão , Vírus da Febre Aftosa , Masculino , Prevalência , Sensibilidade e EspecificidadeRESUMO
Argentina suffered an extensive foot-and-mouth disease (FMD) epidemic between July 2000 and January 2002, 3 months after obtaining the official FMD-free without vaccination status conferred by the World Organization for Animal Health. This is one of the largest FMD epidemics controlled by implementation of a systematic mass vaccination campaign in an FMD-free country. In 2000, 124 herds were reported as FMD positive, 2394 herds in 2001 and one in January 2002; the total number of cattle herds in the country at that time was approximately 230 000. Estimates of FMD transmission are important to understand the dynamics of disease spread and for estimating the value for the parameterization of disease transmission models, with the ultimate goals of predicting its spread, assessing and designing control strategies, conducting economic analyses and supporting the decision-making process. In this study, the within-herd coefficient of transmission, ß, was computed for herds affected in the 2001 FMD epidemic and categorized as low or high based on the median value of ß. A logistic regression model was fitted to identify factors significantly associated with high values of ß. Results suggested that the odds of having a high within-herd transmission were significantly associated with time from initial herd infection to disease detection, date of report, vaccination, and time from initial herd infection to herd vaccination. Results presented in this study demonstrate, in quantifiable terms, the protective impact of vaccination in reducing FMD transmission in infected herds. These results will be useful for the parameterization of epidemiological models aimed at quantifying the impact of vaccination and for the design and implementation of FMD emergency vaccination strategies in face of an epidemic.
Assuntos
Doenças dos Bovinos/transmissão , Surtos de Doenças/veterinária , Vírus da Febre Aftosa/classificação , Febre Aftosa/prevenção & controle , Vacinas Virais/imunologia , Animais , Argentina/epidemiologia , Bovinos , Doenças dos Bovinos/epidemiologia , Surtos de Doenças/prevenção & controle , Febre Aftosa/epidemiologia , Febre Aftosa/transmissão , Modelos Logísticos , Análise Multivariada , Sorotipagem , Fatores de TempoRESUMO
The recurrence and persistence of foot and mouth disease (FMD) could be the consequence of cyclic and massive transportation of calves. For this reason, in South America, vaccination strategies related to livestock dynamic are being promoted. In order to aid the evaluation of such strategies, a method for predicting the risk of transportation of nonvaccinated weaned calves was developed; this method combines expert opinion and empirical evidence using Bayesian estimators. It was applied through Monte Carlo simulation to data of Argentina under four hypothetical vaccination schemes: E1, extended vaccination season of 1/6 of the population of calves each month from July to December without second round vaccination (SRV); E2, extended irregular vaccination from July to December with SRV applied to 70% of the calves resembling the scheme applied in Argentina in 2001; E3, vaccination in November and December without SRV; and E4, vaccination concentrated in November. E1 resulted in probability of transporting non vaccinated calves (tnvc) reaching its maximum in the following year in May with mean=0.0250 and percentile 95% (P95)=0.0404; for the same month tnvc estimates for the other schemes were E2: mean=0.0071; P95=0.0162; E3: mean=0.0017; P95=0.0042 and E4: mean=0.0001; P95=0.0004. Bonferroni multiple comparison for simultaneous assertions for May showed that E4 resulted the best scheme, E1 the worst, and E2 and E3 are intermediate with nonsignificant difference observed between overall (p<0.05). Results were consistent with historical records and quantification for future needs for re-vaccination was made possible. While the ratio "total vaccinated"/"total estimated existences" will give a biased vision of vaccination coverage under the situation of extended vaccination campaigns, a model as the one developed here could allow a more accurate assessment and the design of mitigation plans.
Assuntos
Doenças dos Bovinos/epidemiologia , Febre Aftosa/epidemiologia , Meios de Transporte , Vacinação/veterinária , Vacinas Virais/administração & dosagem , Animais , Animais Recém-Nascidos , Argentina/epidemiologia , Bovinos , Doenças dos Bovinos/prevenção & controle , Doenças dos Bovinos/transmissão , Feminino , Febre Aftosa/prevenção & controle , Febre Aftosa/transmissão , Vírus da Febre Aftosa/imunologia , Vírus da Febre Aftosa/patogenicidade , Masculino , Método de Monte Carlo , Fatores de Risco , Estações do Ano , Vacinas Virais/imunologia , DesmameRESUMO
Habitat fragmentation and diseases have resulted in a decline of the marsh deer (Blastocerus dichotomus) throughout its South American range. Our objectives were to determine whether marsh deer intended for translocation from a region of the Rio Paraná Basin had been infected previously by foot-and-mouth disease virus (FMDV) and whether they were carrying virus. We captured marsh deer from June to October 1998 and collected blood from 108 animals and esophageal-pharyngeal fluid from 53. Serum was tested for antibodies against three FMDV serotypes (O, A, and C) by liquid-phase-blocking sandwich enzyme-linked immunosorbent assay (ELISA). Esophageal-pharyngeal fluid was tested for FMDV RNA by reverse transcription polymerase chain reaction (RT-PCR) and inoculation into three successive baby hamster kidney (BHK-21) cell subcultures, followed by RT-PCR of cultures. We detected low log(10) titers (range 1.0-1.5) to FMDV subtype A(24) Cruzeiro in 19 of 108 sampled marsh deer, but failed to isolate FMDV or detect FMDV RNA in any samples. We conclude that marsh deer from our study site were unlikely to carry FMDV; however, as a preventive measure, the 19 animals with titers for FMDV were not sent to FMDV-free Brazilian states.
Assuntos
Cervos/virologia , Vírus da Febre Aftosa/isolamento & purificação , Febre Aftosa/epidemiologia , Animais , Animais Selvagens/virologia , Anticorpos Antivirais/sangue , Brasil/epidemiologia , Ecossistema , Espécies em Perigo de Extinção , Feminino , Febre Aftosa/transmissão , Vírus da Febre Aftosa/classificação , Vírus da Febre Aftosa/imunologia , Masculino , RNA Viral/análise , Sorotipagem/veterinária , Escarro/virologia , Meios de TransporteRESUMO
The herd reproductive ratio (Rh) and spatio-temporal clustering were estimated in the 2004 foot-and-mouth disease (FMD) epidemic in Peru. The epidemic lasted 39 days and involved 26 herds. Movement of cattle was restricted, all susceptible species within a 25-km buffer zone were revaccinated, and infected animals with clinical signs of FMD were killed or destroyed to control and eradicate the disease. The Rh declined from 5.3 on the second day of the epidemic to 1.31 on the 25th day. Spatio-temporal clustering of cases was detected at a critical distance of 0.5 km and critical times of 7 and 14 days. Cases were clustered in space (P=0.006) but not in time (P=0.498). The space-time scan method detected a spatio-temporal cluster that included consecutive case numbers 13, 14 and 15, located at the temporal midpoint of the epidemic. The values estimated for Rh and the cluster analyses provide quantitative estimates of the self-limiting nature of FMD spread in a susceptible but vaccinated population.
Assuntos
Doenças dos Bovinos/epidemiologia , Controle de Doenças Transmissíveis/métodos , Febre Aftosa/epidemiologia , Conglomerados Espaço-Temporais , Animais , Bovinos , Doenças dos Bovinos/transmissão , Surtos de Doenças , Feminino , Febre Aftosa/transmissão , Vírus da Febre Aftosa/patogenicidade , Masculino , Peru/epidemiologia , Densidade DemográficaRESUMO
The paper presents results from two economic analyses of foot and mouth disease (FMD) in Bolivia. Both recommended a programme to eradicate the disease, but one reported a negative economic return while the later study found a positive and robust return. To investigate the reasons for these differences the paper presents information on cattle movement and how this relates to the epidemiological situation of FMD in Bolivia. This analysis identifies two important trade routes: southern and central cattle trade routes and two FMD endemic areas: the humid tropical areas of the Departments of the Beni and Santa Cruz, and the semi-arid subtropical area to the south east of the country known as the Bolivian Chaco. The farm-level incentives to control FMD in the endemic areas, where cattle are kept in extensive systems, are negative and the main losses caused by the disease occur four to six years after an outbreak. Given this situation it is suggested that resources being used to eradicate the disease in Bolivia should be concentrated in these endemic areas where convincing cattle owners of the need to control FMD is particularly difficult. It is also suggested that the eradication programme should coordinate its activities with neighbouring countries.
Assuntos
Doenças dos Bovinos/economia , Doenças dos Bovinos/transmissão , Comércio , Doenças Endêmicas/veterinária , Febre Aftosa/economia , Febre Aftosa/transmissão , Animais , Bolívia/epidemiologia , Bovinos , Doenças dos Bovinos/prevenção & controle , Surtos de Doenças/economia , Surtos de Doenças/prevenção & controle , Surtos de Doenças/veterinária , Doenças Endêmicas/economia , Doenças Endêmicas/prevenção & controle , Febre Aftosa/prevenção & controle , Meios de Transporte , Vacinação/economia , Vacinação/veterináriaRESUMO
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.
Assuntos
Febre Aftosa/história , Animais , Bovinos , Chile , Febre Aftosa/epidemiologia , Febre Aftosa/transmissão , História do Século XX , HumanosRESUMO
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.
Assuntos
Animais , Bovinos , História do Século XX , Humanos , Febre Aftosa/história , Chile , Febre Aftosa/epidemiologia , Febre Aftosa/transmissãoRESUMO
A model of epidemic dispersal (based on the assumption that susceptible cattle were homogeneously mixed over space, or non-spatial model) was compared to a partially spatially explicit and discrete model (the spatial model), which was composed of differential equations and used geo-coded data (Euclidean distances between county centroids). While the spatial model accounted for intra- and inter-county epidemic spread, the non-spatial model did not assess regional differences. A geo-coded dataset that resembled conditions favouring homogeneous mixing assumptions (based on the 2001 Uruguayan foot-and-mouth disease epidemic), was used for testing. Significant differences between models were observed in the average transmission rate between farms, both before and after a control policy (animal movement ban) was imposed. They also differed in terms of daily number of infected farms: the non-spatial model revealed a single epidemic peak (at, approximately, 25 epidemic days); while the spatial model revealed two epidemic peaks (at, approximately, 12 and 28 days, respectively). While the spatial model fitted well with the observed cumulative number of infected farms, the non-spatial model did not (P<0.01). In addition, the spatial model: (a) indicated an early intra-county reproductive number R of approximately 87 (falling to <1 within 25 days), and an inter-county R<1; (b) predicted that, if animal movement restrictions had begun 3 days before/after the estimated initiation of such policy, cases would have decreased/increased by 23 or 26%, respectively. Spatial factors (such as inter-farm distance and coverage of vaccination campaigns, absent in non-spatial models) may explain why partially explicit spatial models describe epidemic spread more accurately than non-spatial models even at early epidemic phases. Integration of geo-coded data into mathematical models is recommended.