Status of Foot‐and‐mouth Disease in India

Foot‐and‐mouth disease (FMD) is endemic in India and causes severe economic loss. Status of FMD in the country for five fiscal years is presented. Outbreaks were more in number in 2007–2008 than 2010–2011. Three serotypes of FMD virus (O, A and Asia1) are prevalent. Serotype O was responsible for 80% of the confirmed outbreaks/cases, whereas Asia1 and A caused 12% and 8%, respectively. Geographical region‐wise assessment indicated varying prevalence rate in different regions viz; 43% in Eastern region, 31.5% in Southern region, 11.6% in North‐eastern region, 5% Central region, 4.4% Western region and 4% in Northern region. Highest number of outbreaks/cases was recorded in the month of September and lowest in June. Emergence and re‐emergence of different genotypes/lineages within the serotypes were evident in real‐time investigation carried out from time to time. Continues antigenic divergence in serotype A resulted in change in the vaccine strain in 2009. As on date, all genetic diversity within the serotypes is well tolerated by the vaccine strains. Unrestricted animal movements in the country play a major role in the spread of FMD.     

Molecular Characterization of Foot‐and‐Mouth Disease Virus: Implications for Disease Control in Bangladesh

Foot‐and‐mouth disease (FMD) is endemic in Bangladesh, and to implement an effective FMD control programme, it is essential to understand the complex epidemiology of the disease. Here, we report on the characterization of FMD virus (FMDV) recovered from FMD outbreaks in Bangladesh in late 2009. All isolated viruses belonged to the FMDV serotype O. The phylogenetic reconstruction showed that all isolates belonged to the Middle East–South Asia (ME–SA) topotype, but fell into two distinct sublineages, one named Ind‐2001 (the other has not been named). Within both sublineages, the 2009 Bangladesh isolates were most closely related to viruses from Nepal collected during 2008 and 2009. Additionally, both sublineages contained older viruses from India collected in 2000 and 2001. In South Asia, there is extensive cross‐border cattle movement from Nepal and India to Bangladesh. Both these findings have implications for the control of FMD in Bangladesh. Because of the porous borders, a regional FMD control strategy should be developed. Further, animal identification and monitoring animal movements are necessary to identify the cross‐border movements and market chain interactions of ruminants, leading to improved border and movement controls. Additionally, a vaccination strategy should be developed with the initial objective of protecting small‐scale dairy herds from disease. For any successful FMD control programme, long‐term Government commitment and adequate resources are necessary. A sustainable programme will also need farmer education, commitment and financial contributions.     

Epidemiological Patterns of Foot‐and‐Mouth Disease Worldwide

Foot‐and‐Mouth Disease (FMD) is a clinical syndrome in animals due to FMD virus that exists in seven serotypes, whereby recovery from one sero‐type does not confer immunity against the other six. So when considering intervention strategies in endemic settings, it is important to take account of the characteristics of the different serotypes in different ecological systems. FMD serotypes are not uniformly distributed in the regions of the world where the disease still occurs. For example, the cumulative incidence of FMD serotypes show that six of the seven serotypes of FMD (O, A, C, SAT‐1, SAT‐2, SAT‐3) have occurred in Africa, while Asia contends with four sero‐types (O, A, C, Asia‐1), and South America with only three (O, A, C). Periodically there have been incursions of Types SAT‐1 and SAT‐2 from Africa into the Middle East. This paper describes the global dynamics for the seven sero‐types and attempts to define FMD epidemiological clusters in the different regions of the world. These have been described on a continent by continent basis. The review has reaffirmed that the movement of infected animals is the most important factor in the spread of FMD within the endemically infected regions. It also shows that the eco‐system based approach for defining the epidemiological patterns of FMD in endemic, which was originally described in South America, can apply readily to other parts of the world. It is proposed that any coordinated regional or global strategy for FMD control should be based on a sound epidemiological assessment of the incidence and distribution of FMD, identifying risk sources as either primary or secondary endemic eco‐systems.     

The Pathogenesis of Foot‐and‐Mouth Disease I: Viral Pathways in Cattle

In 1898, foot‐and‐mouth disease (FMD) earned a place in history as the first disease of animals shown to be caused by a virus. Yet, despite over a century of active investigation and elucidation of many aspects of FMD pathogenesis, critical knowledge about the virus–host interactions is still lacking. The aim of this review is to provide a comprehensive overview of FMD pathogenesis in cattle spanning from the earliest studies to recently acquired insights emphasizing works which describe animals infected by methodologies most closely resembling natural infection (predominantly aerosol or direct/indirect contact). The three basic phases of FMD pathogenesis in vivo will be dissected and characterized as: (i) pre‐viraemia characterized by infection and replication at the primary replication site(s), (ii) sustained viraemia with generalization and vesiculation at secondary infection sites and (iii) post‐viraemia/convalescence including resolution of clinical disease that may result in long‐term persistent infection. Critical evaluation of the current status of understanding will be used to identify knowledge gaps to guide future research efforts.     

Current Status and Future Prospects to Achieve Foot‐and‐Mouth Disease Eradication in South America

South America has a favourable position with respect to foot‐and‐mouth disease (FMD) compared with other FMD‐affected regions due to the elimination of endemic clinical presentation of the disease. South America has reached the final stage of control and aims to eradicate the disease in the region under the provisions of the Hemispheric Program for the Eradication of FMD 2011–2020 (PHEFA). This programme aims at bringing eradication to completion, thereby eliminating the pool of foot‐and‐mouth disease genotypes active in South America. This plan includes a regional political agreement that provides strategies and technical guidelines for the eradication of foot‐and‐mouth disease from South America. It incorporates knowledge and experience regarding the disease's history and its connection with the different production systems, animal movement and trade. The Pan American Foot and Mouth Disease Center has led the control and eradication programmes, providing the framework for designing national and subregional programmes that have led to significant progress in controlling the disease in South America. The current situation is the result of several factors, including the proper implementation of a national control programmes, good veterinary infrastructure in most countries and public–private participation in the process of eradicating the disease. Notwithstanding the favourable health status, there are significant challenges for the goal of eradication. At this stage, South American countries should enhance their surveillance strategies particularly through the use of target or risk‐based surveys that contribute to increase the degree of sensitivity in the search for viral circulation in the context of absence of clinical occurrence of FMD.     

Review: Evaluation of Foot‐and‐Mouth Disease Control Using Fault Tree Analysis

An outbreak of foot‐and‐mouth disease (FMD) causes huge economic losses and animal welfare problems. Although much can be learnt from past FMD outbreaks, several countries are not satisfied with their degree of contingency planning and aiming at more assurance that their control measures will be effective. The purpose of the present article was to develop a generic fault tree framework for the control of an FMD outbreak as a basis for systematic improvement and refinement of control activities and general preparedness. Fault trees are typically used in engineering to document pathways that can lead to an undesired event, that is, ineffective FMD control. The fault tree method allows risk managers to identify immature parts of the control system and to analyse the events or steps that will most probably delay rapid and effective disease control during a real outbreak. The present developed fault tree is generic and can be tailored to fit the specific needs of countries. For instance, the specific fault tree for the 2001 FMD outbreak in the UK was refined based on control weaknesses discussed in peer‐reviewed articles. Furthermore, the specific fault tree based on the 2001 outbreak was applied to the subsequent FMD outbreak in 2007 to assess the refinement of control measures following the earlier, major outbreak. The FMD fault tree can assist risk managers to develop more refined and adequate control activities against FMD outbreaks and to find optimum strategies for rapid control. Further application using the current tree will be one of the basic measures for FMD control worldwide.     

Foot‐and‐mouth Disease Transmission in Africa: Implications for Control,a Review

In Africa, for the control of foot‐and‐mouth disease (FMD), more information is needed on the spread of the disease at local, regional and inter‐regional level. The aim of this review is to identify the role that animal husbandry, trade and wildlife have on the transmission of FMD and to provide a scientific basis for different FMD control measures in Africa. Review of literature, published reports and databases shows that there is more long distance spread of FMD virus serotypes within North, West, Central and East Africa than in southern Africa. In North, West, Central and East Africa migratory animal husbandry systems often related with search for grazing and water as well as trade are practiced to a greater extent than in southern Africa. In southern Africa, the role of African buffalo (Syncerus caffer) is more extensively studied than in the other parts of Africa, but based on the densities of African buffalo in Central and East Africa, one would assume that buffalo should also play a role in the epidemiology of FMD in this part of Africa. More sampling of buffalo is necessary in West, Central and East Africa. The genetic analysis of virus strains has proven to be valuable to increase our understanding in the spread of FMD in Africa. This review shows that there is a difference in FMD occurrence between southern Africa and the rest of the continent; this distinction is most likely based on differences in animal husbandry and trade systems. Insufficient data on FMD in wildlife outside southern Africa is limiting our understanding on the role wildlife plays in the transmission of FMD in the other buffalo inhabited areas of Africa.     

Detection of Foot‐and‐mouth Disease Virus RNA and Capsid Protein in Lymphoid Tissues of Convalescent Pigs Does Not Indicate Existence of a Carrier State

A systematic study was performed to investigate the potential of pigs to establish and maintain persistent foot‐and‐mouth disease virus (FMDV) infection. Infectious virus could not be recovered from sera, oral, nasal or oropharyngeal fluids obtained after resolution of clinical infection with any of five FMDV strains within serotypes A, O and Asia‐1. Furthermore, there was no isolation of live virus from tissue samples harvested at 28–100 days post‐infection from convalescent pigs recovered from clinical or subclinical FMD. Despite lack of detection of infectious FMDV, there was a high prevalence of FMDV RNA detection in lymph nodes draining lesion sites harvested at 35 days post‐infection, with the most frequent detection recorded in popliteal lymph nodes (positive detection in 88% of samples obtained from non‐vaccinated pigs). Likewise, at 35 dpi, FMDV capsid antigen was localized within follicles of draining lymph nodes, but without concurrent detection of FMDV non‐structural protein. There was a marked decline in the detection of FMDV RNA and antigen in tissue samples by 60 dpi, and no antigen or viral RNA could be detected in samples obtained at 100 dpi. The data presented herein provide the most extensive investigation of FMDV persistence in pigs. The overall conclusion is that domestic pigs are unlikely to be competent long‐term carriers of infectious FMDV; however, transient persistence of FMDV protein and RNA in lymphoid tissues is common following clinical or subclinical infection.     

The Importance of Quality Assurance/Quality Control of Diagnostics to Increase the Confidence in Global Foot‐and‐Mouth Disease Control

The last decade international trade in animals and animal products was liberated and confidence in this global trade can increase only if appropriate control measures are applied. As foot‐and‐mouth disease (FMD) diagnostics will play an essential role in this respect, the Food and Agriculture Organization European Commission for the Control of Foot‐and‐Mouth Disease (EUFMD) co‐ordinates, in collaboration with the European Commission, several programmes to increase the quality of FMD diagnostics. A quality assurance (QA) system is deemed essential for laboratories involved in certifying absence of FMDV or antibodies against the virus. Therefore, laboratories are encouraged to validate their diagnostic tests fully and to install a continuous quality control (QC) monitoring system. Knowledge of performance characteristics of diagnostics is essential to interpret results correctly and to calculate sample rates in regional surveillance campaigns. Different aspects of QA/QC of classical and new FMD virological and serological diagnostics are discussed in respect to the EU FMD directive (2003/85/EC). We recommended accepting trade certificates only from laboratories participating in international proficiency testing on a regular basis.     

Safe and cost‐effective protocol for shipment of samples from Foot‐and‐Mouth Disease suspected cases for laboratory diagnostic

An essential step towards the global control and eradication of foot‐and‐mouth disease (FMD ) is the identification of circulating virus strains in endemic regions to implement adequate outbreak control measures. However, due to the high biological risk and the requirement for biological samples to be shipped frozen, the cost of shipping samples becomes one of major obstacles hindering submission of suspected samples to reference laboratories for virus identification. In this study, we report the development of a cost‐effective and safe method for shipment of FMD samples. The protocol is based on the inactivation of FMD virus (FMDV ) on lateral flow device (LFD , penside test routinely used in the field for rapid immunodetection of FMDV ), allowing its subsequent detection and typing by RT ‐PCR and recovery of live virus upon RNA transfection into permissive cells. After live FMDV collection onto LFD strip and soaking in 0.2% citric acid solution, the virus is totally inactivated. Viral RNA is still detectable by real‐time RT ‐PCR following inactivation, and the virus strain can be characterized by sequencing of the VP 1 coding region. In addition, live virus can be rescued by transfecting RNA extract from treated LFD into cells. This protocol should help promoting submission of FMD suspected samples to reference laboratories (by reducing the cost of sample shipping) and thus characterization of FMDV strains circulating in endemic regions.     

Epidemiology of the 2010 Outbreak of Foot‐and‐Mouth Disease in Mongolia

Foot‐and‐mouth disease (FMD) occurred in five provinces and 24 counties as part of the FMD incursion into Mongolia during 2010. The first detection occurred on 21 April 2010 (confirmed 26 April 2010) with the last detection occurring approximately 8 months later on 13 December 2010. The number of livestock detected in the spring phase of the outbreak was 323 cattle and in the summer phase was 13 485 sheep, 6748 cattle, 5692 goats and 10 camels (total livestock summer phase = 25 935; for spring and summer phases combined = 26 258). Infection of livestock was confirmed by PCR for each affected county but not necessarily for every outbreak cluster involving more than one herder. It is likely that the summer phase of the outbreak was a continuation of the spring event. In the summer phase, the spatio‐temporal pattern of spread suggested an extension of infection from the main cluster in the Sukhbaatar county. There was also a number of long‐distance clusters established. The relative importance of spread by three potential pathways of gazelle, livestock, animal product and fomite movements has not been determined and will require further study. The estimated dissemination ratio (EDR) did not provide evidence of high rate of transmission of infection between herders; however, the data are limited by the quality of surveillance and the method of calculation which used the date of detection rather than the date of infection.     

Foot‐and‐mouth disease virus transmission dynamics and persistence in a herd of vaccinated dairy cattle in India

Foot‐and‐mouth disease (FMD ) is an important transboundary disease with substantial economic impacts. Although between‐herd transmission of the disease has been well studied, studies focusing on within‐herd transmission using farm‐level outbreak data are rare. The aim of this study was to estimate parameters associated with within‐herd transmission, host physiological factors and FMD virus (FMDV ) persistence using data collected from an outbreak that occurred at a large, organized dairy farm in India. Of 1,836 regularly vaccinated, adult dairy cattle, 222 had clinical signs of FMD over a 39‐day period. Assuming homogenous mixing, a frequency‐dependent compartmental model of disease transmission was built. The transmission coefficient and basic reproductive number were estimated to be between 16.2–18.4 and 67–88, respectively. Non‐pregnant animals were more likely to manifest clinical signs of FMD as compared to pregnant cattle. Based on oropharyngeal fluid (probang) sampling and FMDV ‐specific RT ‐PCR , four of 36 longitudinally sampled animals (14%) were persistently infected carriers 10.5 months post‐outbreak. There was no statistical difference between subclinical and clinically infected animals in the duration of the carrier state. However, prevalence of NSP ‐ELISA antibodies differed significantly between subclinical and clinically infected animals 12 months after the outbreak with 83% seroprevalence amongst clinically infected cattle compared to 69% of subclinical animals. This study further elucidates within‐herd FMD transmission dynamics during the acute‐phase and characterizes duration of FMDV persistence and seroprevalence of FMD under natural conditions in an endemic setting.     

Foot‐and‐Mouth Disease Seroprevalence in Cattle in Eritrea

Information about seroprevalence of foot‐and‐mouth disease (FMD) and virus serotypes in Eritrea is unavailable, but is very important as it may guide the choice of intervention measures including vaccination to be implemented. We carried out a cross‐sectional study from February to June 2011 in Eritrea with a two‐stage cluster design, sampling cattle in 155 villages with the objective of determining the seroprevalence of FMD in four administrative regions of the country. We analysed cattle sera (n = 2429) for FMD virus antibodies using the non‐structural ELISA (NS ELISA) and virus neutralization test (VNT). The overall seroprevalence was 26% and 30% for the NS ELISA and VNT, respectively. FMD virus serotypes O (14%) and A (11%) were the most prevalent. Gash Barka showed the highest (39%) seroprevalence both in NS ELISA and VNT compared to the other three administrative regions. Strategic FMD virus vaccination with type O and A (matching circulating strains) in combination of zoo‐sanitary measures would be the best control option for Eritrea which could be started in areas where the disease is less endemic.     

Outbreaks of Foot‐and‐Mouth Disease in Libya and Saudi Arabia During 2013 Due to an Exotic O/ME‐SA/Ind‐2001 Lineage Virus

Foot‐and‐mouth disease viruses are often restricted to specific geographical regions and spread to new areas may lead to significant epidemics. Phylogenetic analysis of sequences of the VP1 genome region of recent outbreak viruses from Libya and Saudi Arabia has revealed a lineage, O‐Ind‐2001, normally found in the Indian subcontinent. This paper describes the characterization of field viruses collected from these cases and provides information about a new real‐time RT‐PCR assay that can be used to detect viruses from this lineage and discriminate them from other endemic FMD viruses that are co‐circulating in North Africa and western Eurasia.     

Evaluation of the Control Strategy for the 2010 Foot‐and‐Mouth Disease Outbreak in Japan Using Disease Simulation

In 2010, Japan experienced a foot‐and‐mouth disease (FMD) epidemic where 292 premises were infected over a period of 75 days. The epidemic was controlled by stamping‐out and vaccination, applied 5 weeks after the first confirmation of disease within a 10 km radius of identified infected places. This study aimed at identifying the role of emergency vaccination to epidemic control while adjusting for the dynamic pattern of local spread, and assessing alternative vaccination strategies, using a disease simulation model. Our results indicate that the overall hazard of local spread remained high throughout the silent spread phase and the first two weeks post‐detection, with significant reduction occurring from week 3 onwards. The estimated effectiveness of emergency vaccination quantified as reduction in the hazard of infection was at most 81% and 44% for cattle and pig farms, respectively. The vaccination strategy reduced the simulated median number of IPs by 22%, epidemic duration by 64% and culling duration by 52%, but increased the total number of infected or vaccinated premises subject to culling by 144% compared with no vaccination. The simulation indicated that vaccination starting 2 weeks earlier (3 weeks post‐first detection) with a smaller vaccination radius (3 km) was more effective for eradication of the epidemic compared with the actually implemented strategy.