Financial Impacts of Foot-and-Mouth Disease at Village and National Levels in Lao PDR

An evaluation of the efficiency and effectiveness of diagnostic tests for foot and mouth disease: are novel diagnostic tests for FMD more feasible than conventional tests in Southeast Asia?

Foot and mouth disease (FMD) remains endemic in many areas of continental Southeast Asia (SEA). It is responsible for substantial economic losses in the smallholder sector and threatens livelihoods. In recent years, novel diagnostic tests have been developed which reportedly detect FMD virus more effectively and efficiently. This critically appraised topic (CAT) aimed to evaluate the feasibility of these diagnostic tests for FMD in SEA compared to conventional tests. Relevant studies that evaluate diagnostic tests are identified and critically assessed, and recommendations are made on suitable potential diagnostic tests for use in the smallholder sector in SEA. A systematic search of electronic databases (CABI: CAB Abstracts, Web of Science Core Collections) was carried out to identify relevant studies that compared novel and conventional diagnostic tests. The search strategy initially identified 12 papers, of which six fulfilled all the inclusion criteria and were selected for this review. Most of the selected studies had limitations in design and comparability, making it difficult to validly compare the effectiveness and efficiency of the relevant diagnostic tests. These limitations include variation in sample characteristics, methodology, measurable outcomes and the different aspects of the diagnostic tests that each study focused on. Most studies concluded that novel diagnostic tests were more effective and efficient than conventional tests: had greater analytical sensitivity and specificity, were more robust, had a wider range of processable sample types and serotypes, could detect various diseases, had faster testing speeds and provided greater value for money. However, strong recommendations on which specific diagnostic test to rely on could not be made, since there was conflicting evidence and multiple confounding factors. Overall, the evidence found did not entirely apply to the target scenario, being SEA smallholder farms. Recommendations for the target scenario were also made based on the study findings.

Investigation of the association between foot-and-mouth disease clinical signs and abattoir serological data in large ruminants in northern Lao People's Democratic Republic

Foot-and-mouth disease (FMD) is a highly infectious and endemic disease in Lao PDR. However, surveillance is weak, and outbreaks are not routinely reported. To address this, serum samples were routinely collected from cattle and buffalo from provincial abattoirs between November 2021 and December 2022. A total of 2,663 serum samples were collected from large ruminants (n = 1,625 cattle; n = 1,038 buffalo) from 17 provinces. Samples were tested for specific antibodies directed against FMD non-structural protein (NSP) to determine the proportion of animals exposed to FMD virus. In addition to sampling from abattoirs, further independent data was collected to report clinical signs and outcomes from 94 districts in 12 northern provinces. These incident reports were recorded by district staff using a Google Form and summarised monthly in the National Animal Disease Reporting System. Information was collected on species, incident date, herd size, location and which clinical signs the animals presented. Overall, 46% of the tested animals returned a positive result using ID Screen® FMD NSP Competition ELISA. Results from serological testing were then compared with reported clinical signs from the same district. In districts reporting 'mouth problems' (regardless of other clinical signs) the median FMD seroprevalence was 49.7%, compared to 31.6% in districts not reporting mouth problems (p = 0.021). This finding suggests that reporting clinical cases of 'mouth problems' could be a potential predictor of FMD infection at a district level in cattle and buffalo in Lao PDR. Furthermore, in districts reporting 'fever', 'mouth problems', and 'nose/mouth secretions' together, the median FMD seroprevalence was 46.2%, compared to 24.4% in districts not reporting these signs (p = 0.033). In districts reporting 'mouth problems' and 'nose/mouth secretions' the median FMD seroprevalence was 49.4%, compared to 25.5% in districts not reporting these signs (p = 0.037). In districts reporting both 'fever' and 'mouth problems,' the median FMD seroprevalence was 46.4% compared to 25% in districts not reporting these signs (p = 0.017). Based on serological data generated by abattoir surveillance, this study identified clinical signs most predictive of FMD seroprevalence. These novel findings can be used to guide passive surveillance efforts in the future specifically in northern Laos and help support improved FMD surveillance more broadly in FMD endemic countries in Southeast Asia.

Economic losses due to foot-and-mouth disease (FMD) in Ethiopian cattle

Ethiopia's cattle population is among the largest in Africa and is burdened by frequent foot-and-mouth disease (FMD) outbreaks. FMD is caused by several distinct and highly contagious viral strains that can result in acute disease in cattle, causing losses in productivity and impeding international trade. This economic simulation study considered four main sources of losses due to FMD in cattle: reduced milk yield, draft power yield, fertility, and increased mortality. Economic losses were estimated per case across age-sex strata in 89 Ethiopian administrative zones for the years 2010-2021 using a wide range of data to estimate distributions for 30 input variables in a series of Monte Carlo simulations. It was estimated that an average case of FMD in Ethiopian cattle results in losses (mean values reported followed 95 % confidence intervals in brackets) of US dollars (USD) 11 (USD 7-USD 16) per case. Losses resulting from an average outbreak were estimated to be USD 2300 (USD 1400-USD 3300), while national annual losses were estimated to be USD 0.9 Mil. (USD 0.2 Mil.-USD 2.3 Mil.). Per cow-year, based on a national cow population of approximately 39 Mil. head, these estimated annual losses are equivalent to losses of only USD 0.02 (USD 0.01-USD 0.06). Nationally, these losses were significantly less than previously estimated in the literature, with currently estimated losses more accurately reflecting the economic burden of FMD in Ethiopian cattle over the past decade. The relatively small estimated losses suggest that control efforts based on widespread vaccination in countries with primarily extensive cattle production systems, such as Ethiopia, are unlikely to be economically sound. Sensitivity analyses suggested losses would be far greater in intensive systems, and that certainty surrounding incidence rates is paramount to the formulation of economically sound animal healthpolicy in regions with endemic FMD.

A Newly Emerging Serotype A Strain in Foot-and-Mouth Disease Virus with Higher Severity and Mortality in Buffalo than in Cattle Calves in North Egypt

A severe foot-and-mouth disease (FMD) epidemic struck several Egyptian provinces recently, causing significant losses among animals even in vaccinated farms. This study indicated the existence of the newly emerging foot-and-mouth disease virus (FMDV) and first investigated its effect on the Egyptian water buffalo (Bubalus bubalis) and cattle calves in the Beheira province, north Egypt. Twenty tongue epithelial samples from diseased calves in five infected farms were randomly collected, prepared, and propagated using baby hamster kidney-21 (BHK-21) cells. Whole genomic RNA was extracted from the cells of the third passage. A FMDV genome was detected and serotyped using one-step reverse transcription polymerase chain reactions (RT-PCRs). Nucleotide sequencing of the purified serotype-specific PCR bands was performed, and a maximum likelihood phylogenetic tree based on 600 base pairs of VP1 was constructed. The results identified FMDV, serotype A in all infected samples, whereas the serotypes O and SAT2 were negative. The obtained 20 sequences were identical to each other and similar to the newly reported strain in Egypt that belongs to the Europe-South America (Euro-SA) topotype. The epidemiological and clinical parameters associated with such a strain were fully recorded by veterinarians and analyzed in a single infected farm including 70 cattle and buffalo calves. It caused higher peracute mortalities in buffalo (25.7%; 95% CI: 13-43) than in cattle (8.6%; 95% CI: 2-24) calves. Severe clinical signs such as dullness, hypothermia, bradycardia, and cardiac arrhythmia were common to both except in fatal cases, whereas hyperthermia and respiratory signs were prevalent in cattle calves. In conclusion, we first characterized the newly emerging FMDV in the calves of Beheira as more fatal and severe in buffalo than in cattle calves.

Impact of risk-based partial vaccination on clinical incidence and seroprevalence of foot and mouth disease in Lao PDR

Foot and mouth disease (FMD) is endemic in the Lao People's Democratic Republic (PDR) and it causes economic loss to smallholder husbandry systems. An intervention programme based on a risk-based partial vaccination strategy was implemented in three provinces of Lao PDR (Champasak, Savannakhet and Xiangkhouang) to immunise domestic cattle and buffalo during 2016-2020. Two cross-sectional surveys were conducted in 2016/17 and 2020 to evaluate the impact of the vaccination programme on the prevalence of FMD virus exposure and clinical incidence of the disease. A total of 212 villages were visited during the two surveys, collecting 1609 household-level questionnaire results and 5931 blood samples of domestic cattle and buffalo. Blood samples were tested for the presence of antibodies to the non-structural proteins of FMD virus, and seroprevalence of 42.5 and 47.5% in 2016/17 and 2020, respectively were found. Multivariable regression analysis indicated that the efficacy of the FMD vaccination programme for reducing FMD virus circulation varied by province. In general, the incidence of clinical FMD increased toward the end of the 5-year intervention period, coinciding with a reduction of vaccine coverage in the last 2 years of the period. The findings suggest that the risk-based vaccination strategy achieved a marginally protective effect against the circulation of FMD virus with the possible limiting factors being operational constraints of public veterinary services, lack of farmers' compliance and unsustainable funding. We conclude that consistent resource availability and higher vaccination coverage is required to successfully control FMD with a risk-based vaccination strategy in Lao PDR.

A cost-benefit analysis of foot and mouth disease control program for smallholder cattle farmers in Cambodia

The Cambodian government is attempting to mobilise government, donor and private sector funding to implement a coordinated FMD vaccination program (FMDVP). A necessary first step is to convince the farmers of the benefits of participating in and potentially financially supporting this program. Information was collected from 300 farmers in order to estimate the on-farm benefits and costs of their participation in an FMDVP. Implementing a successful vaccination program is difficult, and farmers understand from previous experience that there may be institutional, social, technical and financial constraints which limit its success. A benefit-cost analysis needs to take into account that outbreaks do not occur every year, not all cattle will be successfully vaccinated, not all sick animals successfully treated and sometimes sick animals simply sold. This study sensitises these variables in order to give a realistic estimation of the farmer participation benefits in an FMDVP. A general result is that it is worthwhile for farmers to participate in the FMDVP if there are average annual outbreaks, or at least two major outbreaks, in the ensuing 5 years. However, the results are influenced by the interaction of vaccination success and treatment success and coverage. Ineffective coverage and poor treatment of sick animals reduce the benefits of an FMDVP. It is also important that farmers do not sell sick stock and, if they do, that they are able to breed replacements rather than purchase replacements. There are many factors in the smallholder cattle farming system that will influence the success of an FMDVP; farmers will only choose to participate if they can be convinced of the short and long-term economic benefits.

Knowledge affecting foot-and-mouth disease vaccination behavior: traditional dairy farmers in the dry zone of Sri Lanka

The aim of this study was to identify social and farm factors influencing the knowledge of foot-and-mouth disease (FMD), factors influencing participation in FMD vaccination, and vaccination coverage. The study was conducted with 180 traditional dairy farmers who were engaged in cattle and buffalo farming located in three veterinary ranges of the Ampara district in the eastern province of Sri Lanka, during September and October 2019. The probit and tobit regression models were applied to determine the factors. On an average, the scores for knowledge of FMD and hygiene management were calculated as 54.5% and 49.2%, respectively. Farmers’ knowledge of FMD was strongly associated with gender, level of education, and participation in the farmer training program (p < 0.01). The vaccination behavior was enhanced significantly by the number of animals, farming experience, knowledge of FMD score (p < 0.05), and hygiene management score (p < 0.1). It was revealed that social and farm factors contributed to the knowledge of FMD and vaccination behavior. Therefore, we recommend that the livestock educational training program will motivate better participation in the FMD control plan in Sri Lanka.

High seroprevalence of Foot and Mouth Disease in Laos: Call for nationwide vaccination campaigns and disease surveillance

Foot and mouth disease (FMD) virus remains enzootic in Lao People's Democratic Republic (Lao PDR) due to insufficient control measures, including low vaccination coverage. We assessed virus epidemiology and evaluated knowledge, attitude and practice of Lao farmers and animal health stakeholders towards FMD to support politics in devising evidence-based control measures. Sera were collected from 972 domestic ruminants in three provinces of Lao PDR: Vientiane Capital, Vientiane and Xiengkhouang provinces. Seroprevalence of antibodies directed against non-structural proteins of FMD virus was assessed using a commercial ELISA. Positive sera were further characterized by detecting antibodies directed against the structural proteins of FMD serotypes O, A and Asia 1. Information about farm management, biosecurity practices, livestock trade, and past FMD outbreaks was obtained. Overall 35% (340/972) of the ruminants had antibodies against FMD virus with a similar seroprevalence in each province. Seroprevalence depended significantly on the ruminant species (p < .001): 61% of buffaloes, but only 41% of cattle and 15% of goats were seropositive. While antibodies against FMD serotype Asia 1 were absent, 87% (297/340) of the seropositive animals had antibodies against FMD serotype O and 32% (110/340) against FMD serotype A. Many seropositive animals (31%) had antibodies against both serotypes O and A. The majority of the farmers could name the symptoms of FMD and the susceptible animal species. Although many had likely observed FMD outbreaks in their herd and were aware of FMD vaccines, only few vaccinated their animals. This study confirms that FMD remains enzootic in at least three provinces of Lao PDR where vaccination coverage is low. It also shows the relevance of nationwide active and passive disease surveillance, as well as of vaccination campaigns using bivalent FMD vaccines and targeting all susceptible animal species.

Challenges and opportunities for using national animal datasets to support foot-and-mouth disease control

National level databases of animal numbers, locations and movements provide the essential foundations for disease preparedness, outbreak investigations and control activities. These activities are particularly important for managing and mitigating the risks of high-impact transboundary animal disease outbreaks such as foot-and-mouth disease (FMD), which can significantly affect international trade access and domestic food security. In countries where livestock production systems are heavily subsidized by the government, producers are often required to provide detailed animal movement and demographic data as a condition of business. In the remaining countries, it can be difficult to maintain these types of databases and impossible to estimate the extent of missing or inaccurate information due to the absence of gold standard datasets for comparison. Consequently, competent authorities are often required to make decisions about disease preparedness and control based on available data, which may result in suboptimal outcomes for their livestock industries. It is important to understand the limitations of poor data quality as well as the range of methods that have been developed to compensate in both disease-free and endemic situations. Using FMD as a case example, this review first discusses the different activities that competent authorities use farm-level animal population data for to support (1) preparedness activities in disease-free countries, (2) response activities during an acute outbreak in a disease-free country, and (3) eradication and control activities in an endemic country. We then discuss (4) data requirements needed to support epidemiological investigations, surveillance, and disease spread modelling both in disease-free and endemic countries.

Cattle Manure Trade Network Analysis and the Relevant Spatial Pathways in an Endemic Area of Foot and Mouth Disease in Northern Thailand

Animal movement is one of the most important risk factors for outbreaks of foot and mouth disease (FMD) in cattle. Likewise, FMD can spread to cattle farms via vehicles contaminated with the FMD virus. In Northern Thailand, the movement of manure transport vehicles and the circulation of manure bags among cattle farms are considered as potential risk factors for FMD outbreaks among cattle farms. This study aimed to determine the characteristics and movement patterns of manure tradesman using social network analysis. A structured questionnaire was used to identify sequences of farms routinely visited by each tradesman. A total of 611 participants were interviewed, including 154 beef farmers, 407 dairy farmers, 36 tradesmen, and 14 final purchasers. A static weighted directed one-mode network was constructed, and the network metrics were measured. For the manure tradesman–cattle farmer network, the tradesman possessed the highest value of in- and out-degree centralities (71 and 4), betweenness centralities (114.5), and k-core values (2). These results indicated that the tradesman had a high frequency of farm visits and had a remarkable influence on other persons (nodes) in the network. The movement of vehicles ranged from within local districts, among districts, or even across provinces. Unclean manure plastic bags were circulated among cattle farms. Therefore, both vehicles and the bags may act as a disease fomite. Interestingly, no recording system was implemented for the movement of manure transport vehicles. This study suggested that the relevant authority and stakeholders should be aware of the risk of FMD spreading within this manure trading network. The findings from this study can be used as supporting data that can be used for enhancing FMD control measures, especially for FMD endemic areas.

Serological Evidence of Foot-and-Mouth Disease Infection in Goats in Lao PDR

Foot and Mouth Disease (FMD) causes significant economic loss in Lao PDR (Laos) and perpetuates the cycle of smallholder poverty mainly through large ruminant productivity losses, increased costs of production and potential limitations to market access for trade in livestock and their products. Goats are emerging as an important livestock species in Laos, and there is an increasing trend in the number of households with goats, often farmed alongside cattle and buffalo. Although an FMD susceptible species, very little is known about the role of goats in the epidemiology of the disease in Laos. A cross-sectional seroprevalence study was conducted by detecting antibodies to the non-structural proteins (NSP), an indication of a previous infection, and serotype-specific structural proteins (SP) that could be due to vaccination or infection. The study commenced in late 2017 and sera were collected from 591 goats in 26 villages of northern, central and southern Laos. For a subset of sera samples, paired oral swab samples were also collected by a simple random sampling method to detect the prevalence of FMD virus infection at the time of collection. The NSP seroprevalence in the provinces of Borkeo and Xayabouli in the north was 42 and 8%, respectively and in Khammoune in the center, it was 20%. In the other five provinces, Luang Namtha and Luang Prabang (northern Laos), Xieng Khouang and Savannaket (central Laos), and Champasak (southern Laos), the seroprevalence was close to zero. The multivariable analysis indicated that age (p < 0.001) was positively associated with animal-level seropositivity and males were less likely to be seropositive than females (OR: 0.29; 95%CI: 0.10–0.83; p = 0.017). Continued sero-surveillance for FMD in goats is recommended to improve our understanding of their role in the epidemiology of FMD in the region and to extend support to FMD control decisions, particularly regarding vaccination.

A history of FMD research and control programmes in Southeast Asia: lessons from the past informing the future

Foot and mouth disease (FMD) is a major animal health problem within Southeast Asia (SEA). Although Indonesia and more recently the Philippines have achieved freedom from FMD, the disease remains endemic on continental SEA. Control of FMD within SEA would increase access to markets in more developed economies and reduce lost productivity in smallholder and emerging commercial farmer settings. However, despite many years of vaccination by individual countries, numerous factors have prevented the successful control of FMD within the region, including unregulated ‘informal’ transboundary movement of livestock and their products, difficulties implementing vaccination programmes, emergence of new virus topotypes and lineages, low-level technical capacity and biosecurity at national levels, limited farmer knowledge on FMD disease recognition, failure of timely outbreak reporting and response, and limitations in national and international FMD control programmes. This paper examines the published research of FMD in the SEA region, reviewing the history, virology, epidemiology and control programmes and identifies future opportunities for FMD research aimed at the eventual eradication of FMD from the region.

Estimating foot-and-mouth disease (FMD) prevalence in central Myanmar: Comparison of village headman and farmer disease reports with serological findings

The impacts of foot-and-mouth disease (FMD) on food security in developing countries are difficult to quantify due to the scarcity of accurate data on the prevalence and incidence of affected villages. This is partly due to resource constraints as well as the logistical challenges of conducting regular diagnostic testing in remote locations. In this study, we used descriptive analysis and latent class analysis (LCA) models to analyse data collected during a field survey of 160 villages in central Myanmar in the Mandalay and Sagaing Regions over the 2012-2016 time period. We evaluated the performance of verbal reports made by village householders and headmen against serological data to retrospectively determine the FMD-infection status of our study area and to identify factors contributing to under-reporting. Blood samples were collected from approximately 30 cattle per village in both the 6- to 18-month age range and over 18-month age range to distinguish between recent and historic exposure. Village householders were asked to identify pictures of FMD-affected cattle amongst pictures of cattle affected with other common endemic diseases to assess the accuracy of their verbal reporting. The serological results confirmed that FMD is endemic in central Myanmar with village-level seroprevalence estimated at 56% for animals 6-18 months of age and 80% when all age groups were considered together. Most village householders were familiar with the clinical signs of FMD-affected cattle (72%). Based on the results from the LCA models, the village headman had a sensitivity of 77% and specificity of 75% for identifying FMD outbreaks in their village, whereas individual householders had a higher sensitivity and lower specificity of 80% and 56%, respectively. The level of disagreement between the different sources was correlated with the total number of cattle in the village and may potentially be worse in villages where endemic FMD may have led to a high level of natural immunity in cattle and subsequent masking of clinical signs. However, other regional effects such as the intensity of FMD extension efforts cannot be ruled out. Overall, the results suggest that verbal reports of FMD outbreaks from village headmen may be a useful tool to integrate into active FMD surveillance programmes in developing countries.

Peste des Petits Ruminants (PPR) virus serological surveillance in goats in Lao PDR: Issues for disease eradication in a low-resource disease-free setting

Peste des Petits ruminants (PPR) is an economically important transboundary viral disease of goats. This study aimed to determine a baseline of serological evidence for Peste des petits ruminants virus (PPRV) in Lao goats. A total of 1,072 serum samples were collected by convenience sampling across five provinces in Laos and tested for antibody response to PPRV using a commercially available competitive ELISA. Positive antibody responses were found in 2.2% (95% CI 1.4, 3.2) of the samples. True prevalence calculations indicated a total overall sample prevalence of 1.7% (95% CI 0.9, 2.8). The highest provincial seroprevalences were Xiangkhouang (3.5%, 95% CI 1.6, 6.9) and Xayaboury (2.9% (95% CI 1.3, 5.7). There was no association between antibody response and each of the following factors: location, breed, gender or age. Considering the apparent absence of disease manifestation of PPR in Laos, likely explanations for the antibody positivity could include cross reaction to other Morbilliviruses such as Measles or Canine Distemper, importation of pre-vaccinated goats, need for test cut-off re-evaluation to be region specific, or a subclinical and a less virulent circulating virus. This study highlights that the sampled Lao goat population is highly likely to be naïve to PPRV and therefore at risk of an outbreak, possibly by transboundary incursion of livestock from PPR endemic China. Further work is required in the testing of small ruminants in Laos that may eventually provide evidence for a status of freedom from disease, particularly in support of programs aimed at global PPR eradication.

Financial impact of an outbreak of clinically diagnosed blackleg - a case study from Lao PDR

Blackleg (BL) is an acute to peracute highly fatal infectious disease of mainly large ruminants characterised by lesions of myonecrosis caused by Clostridium chauvoei, usually presenting as a sudden onset of sporadic mortalities. In Southeast Asia, ‘BL’ is considered a cause of occasional outbreaks of a subacute febrile illness, although there are few published reports available. Investigation of a major outbreak of clinically diagnosed BL occurring in large ruminants (cattle and buffalo) in three neighbouring villages in central Laos in mid‐2017, was conducted to determine the financial impacts of BL on smallholder livelihoods. Owners of BL‐infected large ruminants in the three affected villages were interviewed (n = 27) and financial losses including losses due to mortality, morbidity and costs of treatments, were determined. The reports of clinical signs of subcutaneous swelling with palpable crepitus in febrile animals were considered consistent with a diagnosis of BL. The outbreak occurred in 47 of a total 449 households with large ruminants across the three villages, affecting 147 of a total population of 3505 ‘at risk’ large ruminants with 71 deaths reported. At the household level, the mean morbidity and mortality rates were 5 ± 4(95% CI: 3–6) and 3 ± 2(95% CI: 1–4) heads per household, respectively. The estimated financial losses due to BL per affected household was USD 822 ± 692(95% CI: 518–1125), being 122% of their annual household income from large ruminant sales. The comparison between the estimated losses due to BL per village and cost of annual BL vaccination programmes, indicated a potential economic benefit of USD3.09 and USD12.37 for every dollar invested in the vaccination programme, if BL outbreaks occur every 20 and 5 years, respectively. This study indicates that clinically diagnosed BL can cause significant losses to smallholder households, and requires Lao animal health authorities to consider vaccination interventions to prevent losses from re‐emergence of BL in the known endemically affected areas.

Foot-and-mouth disease outbreaks due to an exotic serotype Asia 1 virus in Myanmar in 2017

In January 2017, two villages located in Rakhine State of Myanmar reported clinical signs in cattle suggestive of foot-and-mouth disease virus (FMDV) infection. Laboratory analysis identified the outbreak virus as FMDV serotype Asia 1, which represented the first detection of this serotype in Myanmar since 2005 and in the region of South-East Asia (SEA) since 2007. Genetic analysis revealed that the outbreak virus was different from historical viruses from Myanmar and was more closely related to viruses circulating in Bangladesh and India during 2012-2013, indicating that a novel viral introduction had occurred. The precise origin of the outbreaks was not clear, but frequent informal livestock trade with South Asia was reported. Responses to the outbreaks involved disinfection, quarantine and animal movement restrictions; no further outbreaks were detected under the present passive surveillance system. Detection of serotype Asia 1 highlights the complex and dynamic nature of FMDV in SEA. Active surveillance is needed to assess the extent and distribution of this exotic Asia 1 strain and continued vigilance to timely detect the occurrence of emerging and re-emerging FMDV strains is essential.

Social network analysis for the assessment of pig, cattle and buffalo movement in Xayabouli, Lao PDR

The aim of this study is to understand the role that the movement patterns of pigs, cattle and buffalo play in the spread of foot-and-mouth disease (FMD). A cross-sectional survey consisting of a questionnaire was used in a hotspot area for FMD: Xayabouli Province, Lao People’s Democratic Republic. A total of 189 respondents were interviewed. We found that the key players in this network were people who were involved with more than one species of animal or occupation (multipurpose occupational node), which represents the highest number of activities of animals moved off the holding (shown with the highest out-degree centrality) and a high likelihood of being an intermediary between others (shown with the highest betweenness centrality). Moreover, the results show that the animals moved to and away from each node had few connections. Some nodes (such as traders) always received animals from the same group of cattle owners at different times. The subgroup connection within this network has many weak components, which means a connection in this network shows that some people can be reached by others, but most people were not. In this way, the number of connections present in the network was low when we defined the proportion of observed connections with all possible connections (density). These findings indicate that the network might not be busy; only one type of node is dominant which enables increased control of disease spread. We recommend that the relevant authorities implement control measures regarding the key players, which is the best way to effectively control the spread of infectious diseases.

Implementing large Foot and Mouth Disease vaccination programmes for smallholder farmers: lessons from Lao PDR

This study assessed smallholder finances and their attitudes towards the Foot and Mouth Disease (FMD) vaccination programme, when 1 620 000 vaccine doses were provided for strategic administration in large ruminants in FMD 'high-risk' areas in Laos between 2012 and 2016. Farmers (n = 168) in the provinces of Xayyabouli (XYL), Xiengkhoung (XK) and Huaphan (HP), were interviewed. Over 91% of the farmers responded that their livestock were vaccinated for FMD, with over 86% ranking FMD vaccination as a good or very good intervention. No FMD cases were reported from the vaccinated provinces after May 2013. Examination of the total income per household in XYL, XK and HP indicated earnings of US$5060(±650), US$4260(±294) and US$1691(±676), respectively (P = 0.001), with 23%, 28% and 68% of the total incomes from annual sales of large ruminant, respectively. Of the farmers in XYL, XK and HP, 83%, 93% and 70% (P = 0.009) said their annual income increased compared with 2012, and 47%, 64% and 41%, respectively (P = 0.005), indicated this increase was from additional large ruminant sales. The study indicated that this large FMD vaccination programme was well regarded by participating farmers and may have provided satisfactory suppression of the disease in Laos, despite not achieving the preferred vaccination coverage. Continuation of the vaccination programme in FMD high-risk areas is suggested as desirable.

Effect of vaccine storage temperatures and dose rate on antibody responses to foot and mouth disease vaccination in Cambodia

A field study investigated the effects of foot and mouth disease vaccine storage temperature for 7 days (frozen, refrigerated or held at ambient temperature) and dose (half or full dose) on the serological response to vaccination. It utilised a complete factorial design replicated on 18 smallholder cattle farms in three villages in Pursat province, Cambodia. Antibody responses from the 108 cattle involved were assessed by serological examination of blood samples collected at primary vaccination (day 0), at booster vaccination (day 30) and finally at 60 days post primary vaccination. Vaccination responses to the inactivated vaccine were assessed by testing for antibodies directed against FMD structural proteins in a liquid-phase blocking ELISA (LPBE test) and differentiated from responses to natural infection by examining antibody titres against non-structural viral proteins (NSPE test). LPBE results indicated that the mean log10 LPBE antibody titres of all experimental cattle increased from below protective levels at day 0 to protective levels at 30 days post primary vaccination, and increased further at 60 days post primary vaccination. Storage at ambient temperature for 1 week had no effect on antibody response to vaccination. However, freezing the vaccine for a week or use of a half dose resulted in significant reduction in titres at day 60 (P = 0.04 and P = 0.02, respectively). The results of this study reinforce the need to store FMD vaccines within the range recommended by the manufacturers and to adhere to the specified dosage instructions.

Emergence of an exotic strain of serotype O foot-and-mouth disease virus O/ME-SA/Ind-2001d in South-East Asia in 2015

The O/Middle East-South Asia (ME-SA)/Ind-2001 lineage of foot-and-mouth disease virus (FMDV) is endemic in the Indian subcontinent and has been reported in the Middle East and North Africa, but it had not been detected in South-East Asia (SEA) before 2015. This study reports the recent incursions of this viral lineage into SEA, which caused outbreaks in Vientiane Capital of Lao People's Democratic Republic (PDR) in April 2015, in Dak Nong, Dak Lak and Ninh Thuan Provinces of Vietnam from May to October 2015, and in Rakhine State of Myanmar in October 2015. Disease investigations were conducted during the outbreaks and followed up after laboratory results confirmed the involvement of FMDV O/ME-SA/Ind-2001 sublineage d (O/ME-SA/Ind-2001d). Affected host species included cattle, buffalo and pig, and all the outbreaks resolved within 2 months. Animals with clinical signs were separated, and affected premises were disinfected. However, strict movement restrictions were not enforced, and emergency vaccinations were only implemented in Vientiane Capital of Lao PDR and Dak Nong and Ninh Thuan Provinces of Vietnam. Clinical samples were collected from each outbreak and examined by nucleotide sequencing of the FMDV viral protein 1 coding region. Sequence analysis revealed that the O/ME-SA/Ind-2001d isolates from Lao PDR and Vietnam were closely related to each other and similar to viruses previously circulating in India in 2013. Viruses collected from Myanmar were divergent from viruses of the same sublineage recovered from Lao PDR and Vietnam but were closely related to viruses present in Bangladesh in 2015. These findings imply that at least two independent introductions of O/ME-SA/Ind-2001d into SEA have occurred. Our study highlights the transboundary nature of foot-and-mouth disease (FMD) and reinforces the importance of improved FMD surveillance and promotion of safer cross-border trade in SEA to control the risk of introduction and spread of exotic FMDV strains.

Investigation of smallholder farmer biosecurity and implications for sustainable foot-and-mouth disease control in Cambodia

In Cambodia, the majority of the population is rural and reliant on subsistence agriculture, with cattle raised by smallholder farmers using traditional practices, resulting in low productivity and vulnerability to foot-and-mouth disease (FMD). As FMD causes deleterious impacts on rural livelihoods, known FMD risk factors were reviewed, using knowledge, attitudes and practice (KAP) surveys of smallholders (n = 240) from four regions. The study aimed to understand current biosecurity threats to smallholder livelihoods and investigate the hypothesis that smallholder farmers practising FMD risk management should be associated with higher incomes from cattle. Descriptive data were examined to demonstrate trends in KAP and a multivariable linear regression model developed to identify cattle income predictors. Results showed that baseline mean knowledge scores were low at 28.4% across all regions and basic biosecurity practices, including quarantine of new cattle, isolation of sick cattle and FMD vaccination, were lacking. As farmers purchase and sell cattle from and to various administration levels (including export), there is high risk of FMD transmission into and from smallholder communities. The final multivariable linear regression model identified significant explanatory parameters for annual cattle income, including region, number of calves born, forage plot size (ha), vaccination of cattle and the number of cattle purchased (F pr. < 0.001, R²  = 29.9). Individual biosecurity practices including FMD vaccination were not significant predictors of income. With the current focus of farmers on treatment of FMD with inappropriate antibiotics leading to potential anti-microbial residue issues, yet receptivity to payment for vaccine in most regions, there is an urgent need for a coordinated national biosecurity and FMD management public awareness campaign. Further, to enhance the association between improved cattle health and rural livelihoods, it is recommended that livestock development programmes implement a systems approach to enhance farmer KAP in biosecurity, nutrition, reproduction and marketing of cattle.

Foot-and-Mouth Disease Impact on Smallholders - What Do We Know, What Don't We Know and How Can We Find Out More?

Foot‐and‐mouth disease (FMD) endemic regions contain three‐quarters of the world's FMD susceptible livestock and most of the world's poor livestock keepers. Yet FMD impact on smallholders in these regions is poorly understood. Diseases of low mortality can exert a large impact if incidence is high. Modelling and field studies commonly find high FMD incidence in endemic countries. Sero‐surveys typically find a third of young cattle are sero‐positive, however, the proportion of sero‐positive animals that developed disease, and resulting impact, are unknown. The few smallholder FMD impact studies that have been performed assessed different aspects of impact, using different approaches. They find that FMD impact can be high (>10% of annual household income). However, impact is highly variable, being a function of FMD incidence and dependency on activities affected by FMD. FMD restricts investment in productive but less FMD‐resilient farming methods, however, other barriers to efficient production may exist, reducing the benefits of FMD control. Applying control measures is costly and can have wide‐reaching negative impacts; veterinary‐cordon‐fences may damage wildlife populations, and livestock movement restrictions and trade bans damage farmer profits and the wider economy. When control measures are ineffective, farmers, society and wildlife may experience the burden of control without reducing disease burden. Foot‐and‐mouth disease control has benefitted smallholders in South America and elsewhere. Success takes decades of regional cooperation with effective veterinary services and widespread farmer participation. However, both the likelihood of success and the full cost of control measures must be considered. Controlling FMD in smallholder systems is challenging, particularly when movement restrictions are hard to enforce. In parts of Africa this is compounded by endemically infected wildlife and limited vaccine performance. This paper reviews FMD impact on smallholders in endemic countries. Significant evidence gaps exist and guidance on the design of FMD impact studies is provided.