Human‐mediated Foot‐and‐mouth Disease Epidemic Dispersal: Disease and Vector Clusters

Disease clusters were retrospectively explored at national level using a geo‐referenced dataset from the 2001 Uruguayan Foot‐and‐Mouth Disease (FMD) epidemic. Disease location and time (first 11 epidemic weeks) were analysed across 250 counties (of which 160 were infected), without and with control for human mobility related factors (human population and road densities). The null hypothesis of random disease distribution over space and/or time was assessed with: (i) purely temporal; (ii) purely spatial; and (iii) space/time tests. At least within epidemic weeks 2 and 6, a principal disease cluster was observed in 33 contiguous counties (P < 0.01). Two secondary clusters, located at >100 km from each other, were also observed (P < 0.01). The purely spatial test that controlled for human population density identified two non‐contiguous clusters (P < 0.01). Space and time analysis also revealed the same 33 counties as members of the principal cluster, of which 31 were also clustered when human population was controlled (P < 0.01). No clusters were reported by the spatial test when road density was assessed. The hypothesis that human mobility related factors autocorrelate with disease was empirically supported by two pieces of information: (i) removal of human population/road densities eliminated >93.9% of the counties included in the principal disease cluster; and (ii) statistically significant correlations (P < 0.05) were observed in the first three epidemic weeks between road density and the number of cases. Clusters where human population density was associated with 47% greater number of cases/sq. km than that of the principal cluster indicated possible roles as disease vectors (vector clusters). Selective control policy in vector clusters is recommended. Periodic (i.e. weekly) cluster and correlation analyses of both disease and other covariates may facilitate disease surveillance and help design space‐specific control policy.     

Recent Outbreaks of Foot-and-Mouth Disease Type Asia 1 in China

Foot-and-mouth disease (FMD) virus is the aetiological agent of an important disease of livestock and has a great global impact. The outbreak of FMD type Asia 1 in China was first confirmed at the beginning of May 2005. Subsequent outbreaks occurred in 10 areas in different provinces of China.     

国内现有猪口蹄疫O型灭活疫苗对2010年流行毒株的抵抗力

在2010年上半年,猪O型口蹄疫不断发生,作为国内几个生产厂家的猪口蹄疫现用疫苗种毒的提供者,我组进行了猪源流行毒对该种毒灭活疫苗免疫猪的攻毒保护试验及观察。结果如下:1)、猪源流行毒致猪发病速度慢。猪源流行毒接种猪后,致猪发病的时间在3～5天,而疫苗株致猪发病时间是接种后2～3天;2)、该疫苗毒株能有效抵抗猪源流行毒的攻击,PD50大于6;3)、免疫保护和ELISA抗体水平没有线性相关性;4)、免疫保护与140S抗原量有相关性。     

猪口蹄疫特点、流行情况及疫苗使用现状

口蹄疫是危害我国畜牧业的主要传染病之一,主要感染猪、牛、羊等偶蹄动物,其中猪口蹄疫不同于牛、羊口蹄疫,有其独特特点。本文聚焦猪口蹄疫,从其特点、全球流行情况以及我国疫苗使用现状等方面进行了阐述和分析,以期为我国猪口蹄疫防控提供参考。     

An evaluation of Foot-and-Mouth Disease outbreak reporting in mainland South-East Asia from 2000 to 2010

Foot and Mouth Disease (FMD) is considered to be endemic throughout mainland South-East Asia (SEA). The South-East Asia and China FMD (SEACFMD) campaign is a regional control programme which has been ongoing since 1997. The programme encourages countries to submit reports of outbreaks regularly. This paper evolved from a collaboration with SEACFMD to evaluate 10 years worth of reporting. All publicly available outbreak reports (5237) were extracted from the ASEAN Region Animal Health Information System (ARAHIS) for the period from 2000 to mid 2010. These reports included date, outbreak location (at the province and district level) and serotype (if known) plus information on the outbreak size and affected species. Not all records had complete information on the population at-risk or the number of animals affected. This data was transferred into a spatially enabled database (along with data from other sources) and analysed using R and SaTScan. Outbreak serotype was unknown in 2264 (43%) of reports and some countries had very few laboratory confirmed cases (range <1-86%). Outbreak reports were standardised by number of villages in each province. Outbreak intensity varied however there did not appear to be a consistent pattern, nor was there any seasonal trend in outbreaks. Spatial and spatio-temporal cluster detection methods were applied. These identified significant clusters of disease reports. FMD is endemic across the region but is not uniformly present. ARAHIS reports can be regarded as indicators of disease reporting: there may be reports in which laboratory confirmation has not occurred, and in some cases clinical signs are inconsistent with FMD. This raises questions about the specificity of the data. Advances in decentralised testing techniques offer hope for improved verification of FMD as the cause of disease outbreaks. Advances in molecular typing may provide a substantial leap forward in understanding the circulation of FMD in South East Asia.     

Evaluation of foot and mouth vaccination for yak (<Emphasis Type="Italic">Bos grunniens</Emphasis>) in Pakistan

In northern Pakistan, many farming communities rely on domestic yak (Bos grunniens) as a principle source of income. A 2006 participatory disease surveillance report from this region indicated that foot-and-mouth disease (FMD) is the most prevalent annual disease of yak. Our objectives of this study were to determine exposure levels of yak to FMD virus; implement a vaccination program based on current, regional FMD virus serotypes and subtypes; and quantify immune responses following vaccination. Blood samples were used to determine pre-vaccination exposure of animals to FMD virus by antibody presence to non-structural proteins of FMD virus using a 3-ABC trapping indirect ELISA. Vaccine used consisted of FMD serotypes ‘O’ (PanAsia-2), ‘A’ (Iran-05), and ‘Asia-1’ (Shamir), but changed later during the study to match newly circulating viruses in the country (‘O’-PanAsia-2; ‘A’-Turk-06 and Asia-1-Sindh-08). Three hundred sixty-three blood samples were tested from selected villages to determine pre-vaccination FMD virus exposure in yak with an average of 37.7%. Immune responses from initial vaccination and booster dose 30 days later showed clear protective levels (as mean percent inhibition) of antibodies against structural proteins of serotypes ‘O,’ ‘A,’ and ‘Asia-1.’ These responses remained above threshold positive level even at day 210 following initial vaccination. Results of sero-surveillance and anecdotal information of repeated FMD outbreaks demonstrate the persistence of FMD virus of yak in northern Pakistan. Laboratory results and field observations clearly indicated that yak can be protected against FMD with a good quality vaccine with FMD serotype(s) matching current, regionally circulating FMD virus.     

Early and Cost‐Effective Identification of High Risk/Priority Control Areas in Foot‐and‐Mouth Disease Epidemics

Geo‐referenced data from the 2001 Uruguayan foot‐and‐mouth disease (FMD) epidemic were explored to assess whether spatial analysis could lead to cost‐benefit based policies. Four variables were analysed: (i) location and size of 4022 individual rural land parcels, of which 574 were infected over 60 days, (ii) animal density, (iii) percentage of dairy farms per county, and (iv) road density. Each variable was categorized into two to five classes (e.g. small/medium/large) and the proportion of cases per class reported at days 1–3 of the epidemic was compared with that reported at days 4–6. A higher proportion of cases was found at days 4–6 than at days 1–3 in areas with: small and medium size land parcels, high animal density, >20% farms specialized in dairy production, and high road density (P < 0.03 for each). Each of these classes showed a greater proportion of cases at days 7–60 than the proportion of the total territory covered by each class's area (early case concentration ratios: 1.14–1.37). Land parcel clusters were indicated by Moran's I‐test (P < 0.01). A new region was constructed by intersecting the four spatial classes associated with higher proportions of cases at days 4–6. At days 7–60, this region included 50.4% of all cases and represented 30.6% of the territory under study (final case concentration ratio: 1.65). The final area per case in this region was at least 33% lower and covered at least 45% less territory than any of the four single‐variable approaches. Bio‐statistical, multivariate spatial analysis of early cases may greatly increase the efficiency of epidemiologic policy.     

Experimental studies with foot-and-mouth disease virus type Asia-1, responsible for the 2005 epidemic in China

This study was carried out to investigate the biological characteristics of the foot-and-mouth disease (FMD) virus strain Asia-1 China/2005, which is responsible for the 2005 epidemic in China. The result showed that this strain is not host restricted, and could not only cause FMD in cattle and sheep but also in pigs by either inoculation or direct contact.     

猪O型口蹄疫基因工程疫苗候选株的构建及其免疫原性分析

近年来,O型口蹄疫病毒已演化出多种谱系.目前应用的疫苗已不能有效保护多谱系口蹄疫的流行,这给我国猪口蹄疫的防控带来了极大的困难.为了进一步发展免疫原性好、抗原谱广的猪O型口蹄疫疫苗候选株,本研究以O/HN/93现用疫苗毒株的感染性克隆为骨架,构建了含VP3(58位)和VP1(43、48、137、139、140、141和142位)氨基酸改造的全长克隆.线性化的全长cDNA和T7RNA聚合酶质粒共转染BHK细胞后获得拯救病毒.RT-PCR和乳鼠致病性试验表明拯救病毒遗传稳定,具有与亲本病毒相似的致病性.用拯救的基因工程病毒灭活疫苗免疫猪28 d后分别用中国谱系、泛亚谱系和缅甸98谱系猪源毒的流行毒攻击,结果均获得了完全保护(16/16).O/HN/93灭活疫苗免疫猪能完全保护泛亚谱系和缅甸98谱系猪源病毒的攻击(16/16),但不能完全保护(12/16)中国谱系猪源病毒的攻击.结果表明基因工程病毒制备的灭活疫苗提高了对中国型猪源谱系病毒的免疫保护,拓展了抗原谱,是具有良好开发前景的疫苗候选株.     

Experimental infection of wild boar and domestic pigs with a foot and mouth disease virus strain detected in the southeast of Bulgaria in December of 2010

Foot and mouth disease (FMD) was detected in a wild boar in Southeastern Bulgaria in December 2010. The occurrence and spread of the disease in wild cloven-hoofed animals may pose an unexpected and significant threat to FMD virus (FMDV)-free areas within and outside the European Union. So far, only one well documented experimental infection with FMD in wild boar has been published. In order to obtain more epidemiologically relevant data regarding the disease in wild boar we conducted an experiment with the 2010 Bulgarian FMDV type O isolate. Two young wild boar were challenged while two domestic pigs and two additional wild boar served as contact controls. While the domestic pigs developed severe clinical signs of FMD, the wild boar showed relatively mild course of the disease. Viremia started in contact wild boar 2 days post exposure (DPE) and lasted until 6 DPE. The virus shedding lasted until 9 DPE. On 27 DPE, when the animals were slaughtered, viral RNA was detected in lymphoid tissues and oropharyngeal fluid but no virus could be isolated. Commercial ELISAs and virus neutralisation tests detected antibodies against FMDV on 8 or 6 DPE, respectively. The data of the present study will help to understand FMD in wild boar populations and can be used in models to evaluate the potential role of wild boar in FMD epidemiology.     

Evaluation of the transmission risk of foot-and-mouth disease in Japan

The transmission risk of foot-and-mouth disease (FMD) in Japan was evaluated using a mathematical FMD transmission model. The distance-based transmission rate between farms, which was parameterized using the FMD epidemic data in 2010 in Japan, was used to calculate the local-level reproduction numbers—expected numbers of secondary infections caused by one infected farm—for all cattle and pig farms in the country, which were then visualized as a risk map. The risk map demonstrated the spatial heterogeneity of transmission risk in the country and identified risk areas with higher possibility of disease spread. This result suggests that, particularly in high-risk areas, it is important to prepare for the smooth and efficient implementation of control measures against FMD outbreaks.     

Evaluation of genetic and non-genetic factors on foot and mouth disease (FMD) virus vaccine-elicited immune response in Hardhenu (<Emphasis Type="Italic">Bos taurus</Emphasis> x <Emphasis Type="Italic">Bos indicus</Emphasis>) cattle

Foot and mouth disease (FMD) is the most contagious disease of mammals and a major threat to animal husbandry sector. In India, vaccination with the inactivated trivalent (O, A and Asia1) vaccine is one proven way for protecting the livestock from FMD. However, many outbreaks have been reported in different parts of the country. Therefore, present study was aimed at elucidating the effects of genetic and non-genetic factors on FMD viral vaccine-elicited immune response in Hardhenu cattle. The effect of season of vaccination was not consistent. The effect of status of animal was significant for all the pre and post AB titres except for pre AB titre of serotype O and post AB titre of Asia1.The estimates of heritability for response to vaccination were low to high ranging from 0.11 to 0.45. The highest heritability estimate was obtained for serotype O and the lowest for Asia1. The heritability estimates for pre and post AB titres ranged from 0.15 to 0.33. All the pre and post AB titres and responses to vaccination had genetic correlations ranged from high negative to high positive among them. Results of this study highlight the variation in vaccine response which needs to be further exploited on large-scale animal data for better immunization and protection against highly contagious viral vesicular disease of cloven-hoofed animals.     

Foramen magnum decompression with cranioplasty for treatment of caudal occipital malformation syndrome in dogs

Objectives— To describe a cranioplasty procedure used in conjunction with foramen magnum decompression (FMD) for the treatment of canine caudal occipital malformation syndrome (COMS), and to evaluate the clinical outcome. Study Design— Prospective clinical study. Animals— Dogs (n=21) with COMS diagnosed by magnetic resonance imaging (MRI). Methods— After FMD, titanium screws were placed around the perimeter of the foramen magnum defect and a skull plate fashioned from titanium mesh and polymethylmethacrylate was attached to the back of the skull, using the titanium screws as anchor posts. Follow‐up was obtained by direct examination by the authors, telephone interviews with owners and referring veterinarians, and a questionnaire sent to owners of surviving dogs designed to assign objective measures of response to surgical intervention. Surgical success was defined as improvement in ≥1 aspects of clinical dysfunction (e.g. scratching, pain) postoperatively. Owner‐assigned pre‐ and postoperative quality‐of‐life (QOL) scores (1–5) for surviving dogs were compared using a Wilcoxon's signed rank test for paired data (P≤.05). Results— No intraoperative complications occurred and postoperative complications were limited to transient worsening of a pre‐existing head tilt and ataxia in 1 dog, and the need for oral pain medication for 1–4 weeks in 3 dogs. Seventeen dogs (81%) had clinical improvement after surgery. Although clinical signs resolved in 1 dog, it died after being hit by a car, 5 months after surgery. One dog had no change in clinical signs; this patient's clinical signs were not severe and the owners had opted for surgery primarily to prevent progression of disease. Two dogs were euthanatized; 1 because of no improvement of severe clinical signs, and 1 because of sustained recurrence of apparent head and neck pain 7 months later. One dog required a dorsal laminectomy at a second site (C1/C2 vertebral level), 2 months later. Four dogs has transient “flare‐ups” of apparent head/neck pain 2–13 months later; all resolved with transient re‐institution of oral analgesic therapy. Further surgery at the FMD was not needed. Based on the returned questionnaires, there was an overall significant improvement in QOL scores. Conclusions— FMD with cranioplasty was well tolerated, with no intraoperative complications, and minor postoperative complications. Most dogs improved clinically, and none required further surgery at the original FMD site. Clinical Relevance— FMD with cranioplasty may be an effective surgical method of treating dogs with COMS and is well tolerated. Based on prior reports of FMD for this disorder, it appears that cranioplasty may reduce the rate of surgical failure caused by formation of compressive scar tissue at the FMD site in the short term. Results of this preliminary study support further evaluation of the cranioplasty procedure in a larger group of dogs over a more extended follow‐up period.     

Global situation of foot-and-mouth disease (FMD)--a short review

This article reviews the actual world FMD situation. In 2000, fifty nine countries officially reported outbreaks of FMD. The disease occurred in Europe (Greece), Asia (Russia, Mongolia, Bangladesh, Cambodia, China, Japan, Laos, Nepal, Pakistan, Philippines, Republic of Korea, Taiwan, Thailand, Vietnam, Iran, Iraq, Turkey, in Caucasian region--Georgia, Azerbaijan and Armenia as well as in Kazakhstan, Kyrgyzstan, Turkmenistan and Tajikistan), Africa (Egypt, Kenya, Mauritania, South Africa, Tanzania, Uganda, Malawi, Namibia, Zambia and Zimbabwe) and in South America (Brazil, Colombia, Uruguay, Bolivia, Peru, Ecuador and Venezuela). In 2001, FMD was still spreading throughout the endemic regions and appeared in some of the west European countries--Great Britain, The Netherlands, France and Ireland. In South America, FMD occurred in Argentina, Uruguay, Brazil and Colombia. In Asia the FMD spread in Turkey, Iran, Afghanistan, Georgia, Azerbaijan, Mongolia, Kuwait, Bahrain, Yemen, Qatar, United Arab Emirates, Oman, Iran, Bhutan, Nepal, Malaysia, Philippines, Thailand and Taiwan. The FMD situation in Africa was unclear, but probably most countries in West, East and South Africa were affected. The most recent data of the OIE from May 2002 confirmed FMD outbreaks in population of pigs in Republic of Korea.     

Re-emergence of foot-and-mouth disease in Botswana

The re-emergence of foot-and-mouth disease (FMD) in Botswana is reported. The disease outbreak occurred in the Matsiloje Extension Area of Francistown veterinary district situated in the northeastern part of the country in an Office International des épízooties (OIE) recognized FMD free zone without vaccination. The disease affected cattle only and did not spillover into sheep and goats resident in the same extension area, as demonstrated by lack of seroconversion to FMD when tested. The virus isolate associated with the outbreak was identified as FMD virus; Southern African Territories (SAT) type SAT-2. The disease outbreak is discussed in relation to FMD outbreaks that have occurred previously within and outside Botswana.     

The 2010 foot-and-mouth disease epidemic in Japan

Foot-and-mouth disease (FMD) occurred recently for the first time in a decade in Japan. The index case was detected on a beef-breeding farm in Miyazaki Prefecture, Southern Japan, on April 20, 2010. After confirmation of this first case, control measures such as stamping out, movement restriction and disinfection were implemented. However, these strategies proved insufficient to prevent the spread of FMD and emergency vaccination was adopted. Up until the last outbreak on July 4, 2010, a total of 292 outbreaks had been confirmed, with about 290,000 animals having been culled. The epidemic occurred in an area with a high density of cattle and pigs, making disease control difficult. Invasion of the disease into a high-density area aided its rapid spread and led to difficulties in locating suitable burial sites. Epidemiological investigations indicated that the disease was introduced into Japan approximately one month before detection. This delay in initial detection is considered to have allowed an increased number of outbreaks in the early stage of the epidemic. Nevertheless, the epidemic was contained within a localized area in Miyazaki Prefecture and was eradicated within three months because of intensive control efforts including emergency vaccination. Although this epidemic devastated the livestock industry in Japan, many lessons can be learnt for the future prevention and control of infectious diseases in animals.     

Comparative study of experimental Foot-and-Mouth Disease in cattle (<Emphasis Type="Italic">Bos indicus</Emphasis>) and buffaloes (<Emphasis Type="Italic">Bubalis bubalus</Emphasis>)

Foot-and-mouth disease (FMD) is one of the most contagious diseases affecting wide range of host species with variable severity and decreased productivity. The present study was undertaken to compare the clinical and leucocytic changes in indigenous Indian cattle and buffaloes experimentally infected with FMD virus (FMDV) Asia 1. A mild type of disease was observed in the cattle, more so in buffaloes infected with FMDV. Difference in terms of type, site and healing of lesion was observed between cattle and buffaloes. Foot lesions were more common than tongue in buffaloes, which were mainly evident in bulb of the heel in contrast to interdigital foot lesions in cattle. Further, FMDV infection induced a transient moderate leucopenia with lymphopenia in both cattle and buffaloes, but monocyte levels diverged. Relationship between the raised body temperature, leucocytic changes and lesion development was observed. Microscopic changes were observed in the keratinized epithelium of tongue and foot. The findings of the present study indicated the need to investigate the early leucocytic changes in cattle and buffaloes in depth for better understanding of the disease process.     

Experts' Perceptions on China's Capacity to Manage Emerging and Re‐emerging Zoonotic Diseases in an Era of Climate Change

Zoonotic diseases transmitted by arthropods and rodents are a major public health concern in China. However, interventions in recent decades have helped lower the incidence of several diseases despite the country's large, frequently mobile population and socio‐economic challenges. Increasing globalization, rapid urbanization and a warming climate now add to the complexity of disease control and prevention and could challenge China's capacity to respond to threats of emerging and re‐emerging zoonoses. To investigate this notion, face‐to‐face interviews were conducted with 30 infectious disease experts in four cities in China. The case study diseases under discussion were malaria, dengue fever and haemorrhagic fever with renal syndrome, all of which may be influenced by changing meteorological conditions. Data were analysed using standard qualitative techniques. The study participants viewed the current disease prevention and control system favourably and were optimistic about China's capacity to manage climate‐sensitive diseases in the future. Several recommendations emerged from the data including the need to improve health literacy in the population regarding the transmission of infectious diseases and raising awareness of the health impacts of climate change amongst policymakers and health professionals. Participants thought that research capacity could be strengthened and human resources issues for front‐line staff should be addressed. It was considered important that authorities are well prepared in advance for outbreaks such as dengue fever in populous subtropical areas, and a prompt and coordinated response is required when outbreaks occur. Furthermore, health professionals need to remain skilled in the identification of diseases for which incidence is declining, so that re‐emerging or emerging trends can be rapidly identified. Recommendations such as these may be useful in formulating adaptation plans and capacity building for the future control and prevention of climate‐sensitive zoonotic diseases in China and neighbouring countries.     

Epidemiological simulation modeling and spatial analysis for foot-and-mouth disease control strategies: a comprehensive review

Foot-and-mouth disease (FMD) is one of the most serious transboundary, contagious viral diseases of cloven-hoofed livestock, because it can spread rapidly with high morbidity rates when introduced into disease-free herds or areas. Epidemiological simulation modeling can be developed to study the hypothetical spread of FMD and to evaluate potential disease control strategies that can be implemented to decrease the impact of an outbreak or to eradicate the virus from an area. Spatial analysis, a study of the distributions of events in space, can be applied to an area to investigate the spread of animal disease. Hypothetical FMD outbreaks can be spatially analyzed to evaluate the effect of the event under different control strategies. The main objective of this paper is to review FMD-related articles on FMD epidemiology, epidemiological simulation modeling and spatial analysis with the focus on disease control. This review will contribute to the development of models used to simulate FMD outbreaks under various control strategies, and to the application of spatial analysis to assess the outcome of FMD spread and its control.