Clinical variation in foot and mouth disease: sheep and goats

Spatiotemporal analysis of foot and mouth disease outbreaks in cattle and small ruminants in Türkiye between 2010 and 2019

Determining the dynamics associated with foot-and-mouth disease (FMD) outbreaks is important for being able to develop effective strategic plans against the disease. In this direction, spatiotemporal analysis of FMD virus (FMDV) epidemic data that occurred in Türkiye between 2010 and 2019 was carried out. Spatiotemporal analysis was performed by the space-time scan statistic using data from a total of 7,796 FMD outbreaks. Standard deviational ellipse analysis (SDE) was performed to analyse the directional trend of FMD. Five, six, and three significant and high-risk clusters were identified by the space-time cluster analysis for serotypes A, O, and Asia-1, respectively. The SDE analysis indicated that direction of FMD transmission was northeast to southwest. A significant decrease in the number of outbreaks and cases were observed between 2014 and 2019 compared to 2010-2013 (p = 0.010). Most of the serotype A, serotype O, and serotype Asia-1 associated FMD outbreaks were observed during the dry season (April to September). Among FMD cases, cattle and small ruminants accounted for 80.75% (180,932 cases) and 19.25% (43,116 cases), respectively. Among the serotypes detected in the cases, the most frequently detected serotype was serotype O (50.84%), followed by serotypes A (35.67%) and Asia-1 (13.49%). The results obtained in this study may contribute to when and where control programs could be implemented more efficiently for the prevention and control of FMD. Developing risk-defined regional control plans by taking into account the current livestock production including uncontrolled animal movements in border regions, rural livestock, livestock trade between provinces are recommended.

Optimization of a foot-and-mouth disease virus Southern African Territories-specific solid-phase competitive ELISA for small ruminant serum samples

We optimized and verified a single-spot solid-phase competitive ELISA (ss-SPCE) to detect antibodies against structural proteins of Southern African Territories (SAT) serotypes of foot-and-mouth disease virus (FMDV) in small ruminants. Sera from goats vaccinated and experimentally challenged with a SAT1 FMDV pool were tested in duplicate at 4 dilutions (1:10, 1:15, 1:22.5, 1:33.8) to optimize the assay. To assess the performance of the assay in naturally infected animals, we evaluated 316 goat and sheep field sera collected during active SAT2 outbreaks. Relative to results of the virus neutralization test, the optimal serum dilution and cutoff percentage inhibition (PI) were 1:15 and 50%, respectively. At these values, the Spearman rank correlation coefficient was 0.85 (p < 0.001), and the sensitivity and specificity (95% CI) were 80.3% (72.6, 87.2) and 91.1% (84.1, 95.9), respectively. Relative to the liquid-phase blocking ELISA and the nonstructural protein ELISA, the ss-SPCE exhibited divergent performance characteristics between the goat and sheep field sera. Repeatability was better for goats, but the correlation and agreement among all 3 assays were better for the sheep sera. The prevalence of SAT2 FMDV infection in the sampled sheep was 23.6%; sampled goats were seemingly FMDV-free. The ss-SPCE is an appropriate FMDV detection tool to investigate the role of small ruminants in the epidemiology of FMD in Africa.

Knowledge, attitude and practice (KAP) of smallholder farmers on foot-and-mouth disease in Cattle in West Kazakhstan

BACKGROUND

This study was performed to assess the knowledge, attitudes and practices (KAPs) of farmers and veterinary professionals towards foot-and-mouth disease (FMD) in the area studied.

METHODS

The study was based on a comprehensive questionnaire administered through face-to-face interviews. Between January and May 2022, 543 households and 27 animal health practitioners (AHP) were visited in 4 provinces of the West Kazakhstan region to assess their KAPs towards FMD.

RESULTS

A large proportion of herd owners (84%) had known the name of the disease, and nearly a half (48) of respondents had heard of FMD cases on farms in the neighbourhood. Oral mucosa lesions were the most consistent with clinical sign characteristic of FMD among farmers (31.4%), followed by hoof blisters (27.6%) and excessive salivation (18.6%). Farmers reported that new animal introduction was potentially the main factor associated with FMD occurrence in their herds. Over half of farmers (54%) interviewed prefer not to purchase livestock from unknown or potentially epidemiologically disadvantaged areas.

CONCLUSION

All AHPs (27) reported that in their zone of veterinary responsibilities, vaccination against FMD is not practised because the area investigated possesses FMD-free status. However, in the past few years, numerous FMD outbreaks have been detected throughout the region. For this reason, immediate actions need to be taken to prevent further FMD occurrences by giving the region a status of an FMD-free zone with vaccination. The current study demonstrated that inadequate quarantine controls of imported animals, absence of regular vaccination and unrestricted animal movement within the country were the primary obstacles in controlling and preventing FMD in the investigated area.

Factors associated with foot-and-mouth disease seroprevalence in small ruminants and identification of hot-spot areas in northern Nigeria

Many small ruminants infected with foot-and-mouth disease (FMD) remain asymptomatic, with the capacity to promote silent viral spread within domestic and wildlife species. However, little is known about the epidemiological role played by small ruminants in FMD. In particular, there are few studies that examine FMD seroprevalence, spatial patterns and risk factors for exposure in small ruminants. A cross-sectional study was conducted in northern Nigeria (Bauchi, Kaduna, and Plateau States) to determine the true seroprevalence of FMD in backyard small ruminants, identify factors associated with FMD seroconversion at animal and household levels, and identify spatial patterns for FMD virus exposure. Data on animal (n = 1800) and household (n = 300) characteristics were collected using a standardised questionnaire. Sera samples from 1800 small ruminants were tested for antibodies against non-structural proteins of FMD virus. True seroprevalence was estimated stochastically to account for variability and uncertainty in the test sensitivity and specificity previously reported. Risk factors for FMD seropositivity were identified at animal and household levels and spatial patterns were determined. The overall true seroprevalence for FMD virus, in the small ruminant population tested, was estimated to be 10.2 % (95 % Credible Interval (CrI) 0.0-19.0), while State-level estimates were 17.3 % (95 % CrI 0.0-25.8) for Kaduna, 6.9 % (95% CrI 0.0-15.8) for Bauchi, and 3.6 % (95 % CrI 0.0-12.6) for Plateau. State and species were the main risk factors identified at animal level, with interaction detected between them. Compared to goats in Plateau, the odds of testing positive were higher for goats in Bauchi (Odds Ratio (OR)= 1.83, 95 % CI 1.13-2.97, p = 0.01) and Kaduna (OR=2.97, 95 % CI 1.89-4.67, p < 0.001), as well as for sheep in Plateau (OR=3.78, 95 % CI 2.08-6.87, p < 0.001), Bauchi (OR=1.61, 95 % CI 0.91-2.84, p = 0.10), and Kaduna (OR=3.11, 95 % CI 1.61-6.01, p = 0.001). Households located in Kaduna were more likely to have a higher number of seropositive SR compared to those in Plateau (Prevalence Ratio (PR)= 1.75, 95 % CI 1.30-2.36, p < 0.001), and households keeping sheep flocks were more likely to be seropositive (from 1 to 10 sheep: PR=1.39, 95 % CI 1.05-1.82, p = 0.02; more than 10 sheep: PR=1.55, 95 % CI 1.12-2.15, p = 0.008) compared to those that did not keep sheep. A hot-spot was detected in Kaduna, and a cold-spot in Plateau. These results reveal that small ruminants had been recently exposed to FMD virus with spatial heterogeneity across the study area.

Main factors associated with foot-and-mouth disease virus infection during the 2001 FMD epidemic in Uruguay

Large epidemics provide the opportunity to understand the epidemiology of diseases under the specific conditions of the affected population. Whilst foot-and-mouth disease (FMD) epidemics have been extensively studied in developed countries, epidemics in developing countries have been sparsely studied. Here we address this limitation by systematically studying the 2001 epidemic in Uruguay where a total of 2,057 farms were affected. The objective of this study was to identify the risk factors (RF) associated with infection and spread of the virus within the country. The epidemic was divided into four periods: (1) the high-risk period (HRP) which was the period between the FMD virus introduction and detection of the index case; (2) the local control measures period (LCM) which encompassed the first control measures implemented before mass vaccination was adopted; (3) the first mass vaccination, and (4) the second mass vaccination round. A stochastic model was developed to estimate the time of initial infection for each of the affected farms. Our analyses indicated that during the HRP around 242 farms were probably already infected. In this period, a higher probability of infection was associated with: (1) animal movements [OR: 1.57 (95% CI: 1.19-2.06)]; (2) farms that combined livestock with crop production [OR: 1.93 (95% CI: 1.43-2.60)]; (3) large and medium farms compared to small farms (this difference was dependent on regional herd density); (4) the geographical location. Keeping cattle only (vs farms that kept also sheep) was a significant RF during the subsequent epidemic period (LCM), and remained as RF, together with large farms, for the entire epidemic. We further explored the RF associated with FMDV infection in farms that raised cattle by fitting another model to a data subset. We found that dairy farms had a higher probability of FMDV infection than beef farms during the HRP [OR: 1.81 (95% CI: 1.12-2.83)], and remained as RF until the end of the first round of vaccination. The delay in the detection of the index case associated with unrestricted animal movements during the HRP may have contributed to this large epidemic. This study contributes to the knowledge of FMD epidemiology in extensive production systems.

FTA Cards as a Rapid Tool for Collection and Transport of Infective Samples: Experience with Foot-and-Mouth Disease Virus in Libya

Foot-and-mouth disease (FMD) is a viral disease, widespread and highly contagious, that mainly affects cloven-hoofed domestic and wild animals. FMD can lead to high economic losses due to the reduction in animal production such as a drop in milk production, loss of body weight, and a high mortality rate in young ruminants. Sixteen samples were collected from animals showing typical clinical signs of FMD during the last FMD outbreak in Libya in 2018-2019. Flinders Technology Associates (FTA) cards impressed with blood, swabs, or vesicular epithelium samples were shipped to the WOAH FMD reference laboratory in Brescia, Italy, and tested for the detection of FMD viruses. Nucleic acids were extracted from the FTA cards, and molecular testing based on real-time RT-PCR assays was carried out, of which one was specifically designed for the detection of the FMD virus of serotype O, topotype O/East Africa-3 (O/EA-3), that was further confirmed by a sequence analysis of the VP1 gene. The phylogenetic analysis of the VP1 gene showed a nucleotide identity of more than 99% between the virus circulating in Libya and the FMD virus strains isolated in Algeria in 2019.

Seroepidemiology of selected transboundary animal diseases in goats in Zambia

Transboundary pathogens of goats present significant constraints to the livelihoods of millions of farmers in countries such as Zambia. Consequently, this study aimed to investigate the seroprevalence of Mycoplasma capricolum subsp. capripneumoniae (Mccp), foot and mouth disease virus (FMDV), Brucella spp., Crimean Congo haemorrhagic fever virus (CCHFV), and Rift Valley fever virus (RVFV) in Zambian goats. Another aim was to identify associations between seroprevalence and different predictor variables, such as trade and border proximity. From September to October 2019, 962 serum samples were collected from goats in seven Zambian districts, four of which have an international border while the remaining three do not. A questionnaire survey was conducted with each household, focusing on trade routines, management strategies and herd disease history. Animal-level seroprevalence adjusted for herd-level clustering was 8.2 % (95 % confidence interval [CI] 7.5-9.0) for Mccp, 12.9% (95% CI 12.0-13.7) for FMDV, 13.0 % (95% CI 12.1-13.9) for Brucella spp., 3.3 % (95% CI 2.8-3.7) for CCHFV, and 0.4 % (95 % CI 0.3-0.7) for RVFV. The association between herd-level seroprevalence and border proximity and trade appeared negligible, with the exception of selling goats at least twice a year which was identified as a potential risk factor for Brucella spp. (OR 4.1, 95 % CI 1.1-16.0, p = 0.040). In addition, a positive association between herd-level seroprevalence of FMDV and a herd size of 21 goats or more (OR 3.3, 95 % CI 1.0-11.1, p = 0.049) was detected. Also, positive associations between animal-level seroprevalence of Brucella spp. and increasing age (OR 7.7, 95 % CI 1.5-40.7, p = 0.016), and CCHFV and keeping pigs in the household (OR 2.7, 95 % CI 1.0-7.1, p = 0.044), were found. For FMDV (OR 3.8, 95 % CI 1.4-10.9, p = 0.011) and Brucella spp. (OR 4.5, 95 % CI 1.2-17.3, p = 0.031) on the other hand, animal-level seroprevalence was significantly higher in households without pigs. To the best of the authors' knowledge, this is the first study to describe the presence of antibodies for CCPP and CCHF in the Zambian goat population. While the association between seroprevalence and trade and border proximity generally appeared negligible, it is recommended that their influence is further evaluated in future studies, preferably through in-depth longitudinal studies incorporating impacts of different biosecurity measures and trade variations, linked to for example seasonality and trade peaks.

Crossing the Line: Seroprevalence and Risk Factors for Transboundary Animal Diseases Along the Tanzania-Zambia Border

Transboundary pathogens pose a threat to livelihood security in countries such as Zambia and Tanzania. This study aimed to investigate the seroprevalence of peste des petits ruminants virus (PPRV), foot and mouth disease virus (FMDV), sheep and goat pox virus (SGPV), Rift Valley fever virus (RVFV) and Brucella spp. in sheep and goats along the Tanzania-Zambia border. Another aim was to assess the association between certain predictor variables and seroprevalence, focusing on trade and proximity to an international border, to a town and to the Tanzania-Zambia highway. During September-October 2018, 486 serum samples from small ruminants in Zambia and 491 in Tanzania were collected and analyzed using enzyme-linked immunosorbent assays (ELISA). A questionnaire focused on management strategies was administered to each household. The animal-level seroprevalence in Zambia was 0.21% [95% confidence interval (CI) (0.01–1.14) for PPRV, 1.03% (95% CI 0.33–2.39) for FMDV, 0% (95% CI 0–0.76) for SGPV, 2.26% (95% CI 1.14–4.01) for RVFV and 1.65% (95% CI 0.71–3.22) for Brucella spp.]. In Tanzania, animal-level seroprevalence was 2.85% (95% CI 1.57–4.74) for PPRV, 16.9% (95% CI 13.7–20.5) for FMDV, 0.20% (95% CI 0.01–1.13) for SGPV, 3.26% (95% CI 1.87–5.24) for RVFV and 20.0% (95% CI 14.5–26.5) for Brucella spp. For PPRV (OR 6.83, 95% CI 1.37–34.0, p = 0.019) and FMDV (OR 5.68, 95% CI 1.58–20.3, p = 0.008), herds situated more than 30 km from an international border were more likely to be seropositive, while being located 10–30 km (OR 4.43, 95% CI 1.22–16.1 p = 0.024) from a border was identified as a risk factor for Brucella spp. For FMDV (OR 79.2, 95% CI 4.52–1388.9, p = 0.003), being situated within 30 km from a town was associated with seropositivity. Furthermore, contact with wild ruminants (OR 18.2, 95% CI 1.36–244), and the presence of sheep in the household (OR 5.20, 95% CI 1.00–26.9, p = 0.049), was associated with seropositivity for PPRV, and FMDV. No significant associations between trade or distance to the Tan-Zam highway and seroprevalence were found. We recommend that the impact of trade and proximity to borders, towns and roads should be further evaluated in larger studies, ideally incorporating aspects such as temporal trade fluctuations.

A Five-Year Retrospective Study of Foot-and-Mouth Disease Outbreaks in Southern Africa, 2014 to 2018

Foot-and-mouth disease (FMD) virus (FMDv), like other ribonucleic acid (RNA) genome viruses, has a tendency to mutate rapidly. As such, available vaccines may not confer enough cross-protection against incursion of new lineages and sublineages. This paper is a retrospective study to determine the topotypes/lineages that caused previous FMD outbreaks in 6 southern African countries and the efficacy of the current vaccines to protect cattle against them. A total of 453 bovine epithelial tissue samples from 33 FMD outbreaks that occurred in these countries from 2014 to 2018 were investigated for the presence of FMDv. The genetic diversity of the identified Southern African Type (SAT)-FMD viruses was determined by comparing sequences from outbreaks and historical prototype sequences. Of the 453 samples investigated, 176 were positive for four FMDv serotypes. Out of the 176 FMD positive cases there were 105 SAT2 samples, 32 SAT1 samples, 21 SAT3 samples, and 18 serotype O samples. Phylogenetic analysis grouped the SATs VP1 gene sequences into previously observed topotypes in southern Africa. SAT1 viruses were from topotypes I and III, SAT2 viruses belonged to topotypes I, II, III, and IV, and SAT3 viruses were of topotypes I and II. Vaccine matching studies on the field FMDv isolates produced r 1-values greater than or equal to 0.3 for the three SAT serotypes. This suggests that there is no significant antigenic difference between current SAT FMD vaccine strains and the circulating SAT serotypes. Therefore, the vaccines are still fit-purpose for the control FMD in the region. The study did not identify incursion of any new lineages/topotypes of FMD into the sampled southern African countries.

Assessment of foot-and-mouth disease risk areas in mainland China based spatial multi-criteria decision analysis

Background

Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals. As a transboundary animal disease, the prevention and control of FMD are important. This study was based on spatial multi-criteria decision analysis (MCDA) to assess FMD risk areas in mainland China. Ten risk factors were identified for constructing risk maps by scoring, and the analytic hierarchy process (AHP) was used to calculate the criteria weights of all factors. Different risk factors had different units and attributes, and fuzzy membership was used to standardize the risk factors. The weighted linear combination (WLC) and one-at-a-time (OAT) were used to obtain risk and uncertainty maps as well as to perform sensitivity analysis.

Results

Four major risk areas were identified in mainland China, including western (parts of Xinjiang and Tibet), southern (parts of Yunnan, Guizhou, Guangxi, Sichuan and Guangdong), northern (parts of Gansu, Ningxia and Inner Mongolia), and eastern (parts of Hebei, Henan, Anhui, Jiangsu and Shandong). Spring is the main season for FMD outbreaks. Risk areas were associated with the distance to previous outbreak points, grazing areas and cattle density. Receiver operating characteristic (ROC) analysis indicated that the risk map had good predictive power (AUC=0.8634).

Conclusions

These results can be used to delineate FMD risk areas in mainland China, and veterinary services can adopt the targeted preventive measures and control strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03084-5.

Epidemiological study on foot-and-mouth disease in small ruminants: Sero-prevalence and risk factor assessment in Kenya

Foot-and-mouth disease (FMD) is endemic in Kenya affecting cloven-hoofed ruminants. The epidemiology of the disease in small ruminants (SR) in Kenya is not documented. We carried out a cross-sectional study, the first in Kenya, to estimate the sero-prevalence of FMD in SR and the associated risk factors nationally. Selection of animals to be sampled used a multistage cluster sampling approach. Serum samples totaling 7564 were screened for FMD antibodies of non-structural-proteins using ID Screen^® NSP Competition ELISA kit. To identify the risk factors, generalized linear mixed effects (GLMM) logistic regression analysis with county and villages as random effect variables was used. The country animal level sero-prevalence was 22.5% (95% CI: 22.3%-24.3%) while herd level sero-prevalence was 77.6% (95% CI: 73.9%-80.9%). The risk factor that was significantly positively associated with FMD sero-positivity in SR was multipurpose production type (OR = 1.307; p = 0.042). The risk factors that were significantly negatively associated with FMD sero-positivity were male sex (OR = 0.796; p = 0.007), young age (OR = 0.470; p = 0.010), and sedentary production zone (OR = 0.324; p<0.001). There were no statistically significant intra class correlations among the random effect variables but interactions between age and sex variables among the studied animals were statistically significant (p = 0.019). This study showed that there may be widespread undetected virus circulation in SR indicated by the near ubiquitous spatial distribution of significant FMD sero-positivity in the country. Strengthening of risk-based FMD surveillance in small ruminants is recommended. Adjustment of husbandry practices to control FMD in SR and in-contact species is suggested. Cross-transmission of FMD and more risk factors need to be researched.

Knowledge, Attitudes, and Practices (KAPs) of Farmers on Foot and Mouth Disease in Cattle in Baghlan Province, Afghanistan: A Descriptive Study

Simple Summary

Foot and mouth disease (FMD) affects the productivity and health of several animals species, including cattle. In Afghanistan, cattle represent a valuable source of food security and play a vital role in the rural economy. Using a questionnaire-based approach, we evaluated the self-reported knowledge, attitudes, and practices of various stakeholders involved in the cattle industry and veterinary management of animal health in a northern province of Afghanistan. The study pointed to several aspects that could be translated into practical management options to add value to FMD management in the cattle industry in Afghanistan.

Abstract

This study was performed to investigate the knowledge, attitudes, and practices (KAPs) of farmers, animal traders, and veterinary professionals on FMD in Baghlan province, Afghanistan. Four structured questionnaires were administered to the respondents. Almost half (48.5%) of the farmers had heard of the occurrence of FMD in their neighbourhood or knew the name of the disease. The majority of farmers could recognise the clinical signs of FMD in their animals (salivation, 85.9%; tongue ulcers, 78.8%; gum lesions, 78.2%; hoof lesions, 76.8%). Most farmers stated that the “introduction of new animals” was the primary cause of FMD appearing on their farms and to control the spread of the disease, over half of the farmers (56%) preferred not to buy cattle from unknown or potentially infected sources. Animal traders’ knowledge was limited to recognising some clinical signs of the disease such as: salivation, and lesions in the mouth and on the feet. No animals were directly imported by the traders from outside Afghanistan. Over half of the local veterinary professionals (65%) kept record books of the animal diseases seen and/or treatment plans undertaken, and 80% of them reported the occurrence of FMD to the provincial, regional, and central veterinary authorities. No regular vaccination programme against FMD was implemented in the province. Poor import controls and quarantine were considered to be the main barriers to the control of FMD in the study area and the surrounding provinces. It can be concluded that, despite relatively good knowledge about FMD in the study area, there are gaps in farmers’ and traders’ knowledge that need to be addressed to overcome the burden of the disease in the province. These should focus on strengthening interprovincial quarantine measures and implementation of regular vaccination campaigns against the circulating FMDV within the area.

Viral infections shared between water buffaloes and small ruminants in Switzerland

Importation of exotic animals that may harbor infectious agents poses risks for native species with potentially severe impacts on animal health and animal production. Although the Asian water buffalo (Bubalus bubalis) population in Europe is steadily increasing, its susceptibility to viral infections and its role for interspecies transmission is largely unknown. To identify viral infections that are shared between exotic water buffaloes and native small ruminants, we collected blood samples from 3 Swiss farms on which water buffaloes were kept either without, or together with, sheep or goats. These samples were analyzed by next-generation sequencing (NGS) as well as by selected conventional tests, including PCR, ELISA, and in some cases a virus neutralization test. By NGS, a novel virus of the genus Gemykrogvirus (GyKV; Genomoviridae) was first detected in the buffaloes on one farm, and subsequently confirmed by PCR, and was also detected in the co-housed sheep. In contrast, this virus was not detected in buffaloes on the farms without sheep. Moreover, conventional methods identified a number of viral infections that were not shared between the exotic and the native animals, and provided evidence for potential roles of water buffaloes in the epidemiology of ruminant pestiviruses, especially bovine viral diarrhea virus, bluetongue virus, and possibly bovine alphaherpesvirus 2. Our results clearly indicate that water buffaloes are susceptible to interspecies viral transmission and may act as intermediate hosts, or even as reservoirs, for these viruses.

Evolutionary and Ecological Drivers Shape the Emergence and Extinction of Foot-and-Mouth Disease Virus Lineages

Livestock farming across the world is constantly threatened by evolutionary turnover of foot-and-mouth disease virus (FMDV) strains in endemic systems, the underlying dynamics of which remain to be elucidated. Here, we map the eco-evolutionary landscape of co-circulating FMDV lineages within an important endemic virus pool encompassing Western, Central and parts of Southern Asia, reconstructing the evolutionary history and spatial dynamics over the last 20 years that shapes the current epidemiological situation. We demonstrate that new FMDV variants periodically emerge from Southern Asia, precipitating waves of virus incursions that systematically travel in a westerly direction. We evidence how metapopulation dynamics drive the emergence and extinction of spatially structured virus populations, and how transmission in different host species regulates the evolutionary space of virus serotypes. Our work provides the first integrative framework that defines co-evolutionary signatures of FMDV in regional contexts to help understand the complex interplay between virus phenotypes, host characteristics, and key epidemiological determinants of transmission that drive FMDV evolution in endemic settings.

Ovarian activity in crossbred Thai native does during naturally occurring foot-and-mouth disease (FMD) virus infection

This study aimed to compare the follicular dynamics in goats during naturally infected with foot-and-mouth disease virus (FMD) subjected to induced ovulations, and after disease recovery, crossbred Thai native does were synchronized with CIDR for 14 days, and then PGF_2α and PMSG were administered on the day following CIDR removal. The ovarian activity was determined by transrectal ultrasonography. Clinical signs (fever, anorexia, lameness, and foot lesion) were observed on day 12 post-estrus (day 0, day of expected estrus). The study was carried out for 2 periods: FMD outbreak (day 0-day 21) and FMD recovery (day 63-day 84). Infected does were classified into two groups: (I) does without (n = 5) and (II) does with clinical signs (n = 5). The results showed that during FMD outbreak, the number of follicles/waves and number of follicles > 5 mm in ovulatory follicle wave of group II were lower than those of group I and those of its own group after FMD recovery (P<0.05). Higher in follicular regression rate were found in group II compared to group I in the does with 3 follicular waves during FMD outbreak (P<0.05). Moreover, during FMD outbreak, the does had lower number of follicles > 5 mm and longer day of emergence and day of largest follicles in ovulatory follicle wave than of those after FMD recovery. This observation demonstrated that FMD impaired folliculogenesis in goats, and the ovarian activity could be restored about 1 month after disease recovery.

Secure Sheep and Wool Supply Plan for Continuity of Business

Sheep operations will be subject to movement controls during a US foot and mouth disease outbreak and should be prepared to manage animal and product movement disruptions. The voluntary Secure Sheep and Wool Supply (SSWS) Plan for Continuity of Business provides tools for the sheep industry to develop contingency plans, write enhanced, operation-specific biosecurity plans, and learn about disease surveillance opportunities and challenges. The SSWS Plan is science-based and risk-based, funded by the American Sheep Industry Association, and developed collaboratively with industry, government officials, and veterinarians at Iowa State University. For more information, visit www.securesheepwool.org.

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.

Risk factors for the incursion, spread and persistence of the foot and mouth disease virus in Eastern Rwanda

BACKGROUND

Identification of risk factors is crucial in Foot-and-mouth disease (FMD) control especially in endemic countries. In Rwanda, almost all outbreaks of Foot-and-Mouth Disease Virus (FMDV) have started in Eastern Rwanda. Identifying the risk factors in this area will support government control efforts. This study was carried out to identify and map different risk factors for the incursion, spread and persistence of FMDV in Eastern Rwanda. Questionnaires were administered during farm visits to establish risk factors for FMD outbreaks. Descriptive statistical measures were determined and odds ratios were calculated to determine the effects of risk factors on the occurrence of FMD. Quantum Geographic Information System (QGIS) was used to produce thematic maps on the proportion of putative risk factors for FMD per village.

RESULTS

Based on farmers' perceptions, 85.31% (with p < 0.01) experienced more outbreaks during the major dry season, a finding consistent with other reports in other parts of the world. Univariate analysis revealed that mixed farming (OR = 1.501, p = 0.163, CI = 95%), and natural breeding method (OR = 1.626; p = 0.21, CI = 95%) were associated with the occurrence of FMD indicating that the two risk factors could be responsible for FMD outbreaks in the farms. The occurrence of FMD in the farms was found to be significantly associated with lack of vaccination of calves younger than 12 months in herds (OR = 0.707; p = 0.046, CI = 95%).

CONCLUSIONS

This is the first study to describe risk factors for persistence of FMDV in livestock systems in Rwanda. However, further studies are required to understand the role of transboundary animal movements and genotypic profiles of circulating FMDV in farming systems in Rwanda.

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.

Outbreak investigation of foot and mouth disease in Nangarhar province of war-torn Afghanistan, 2014

Afghanistan has long history of ongoing conflicts, resulting in massive destruction of the country's infrastructure. Illegal trade of livestock between Afghanistan and Pakistan boosted the spread of Foot & Mouth Disease (FMD). Current study was conducted to investigate outbreaks of FMD occurred between April-August 2014 in Nangarhar, Afghanistan. Descriptive data about suspected FMD cases were collected from the Civil Veterinary Hospital, Nangarhar to analyze spatio-temporal pattern of FMD. Case farms (n = 137) were selected from list of clinically confirmed FMD outbreaks available in the hospital. Control farms (n = 137) were enrolled from neighboring premises of case farms. The epidemic curve showed that the virus is continuously circulating among susceptible population. The mean age of the oldest lesion was 2.8 days. Foot & Mouth Disease was more likely to occur in female animals compared to male animals (p < 0.001). Farmers having no ability to clinically recognize FMD (OR 5.8, 95% CI 1.4-23.8); previously having any FMD case in herd (OR 11.8, 95% CI 3.0-45.8), farms where animals leave shed during day (OR 15.4, 95% CI 5.6-42.0), and farms, where neighboring farmers used to visit the premises (OR 3.5, 95% CI 1.2-9.9) were identified as risk factors. Current findings may be used to create awareness of concerned veterinary health authorities about FMD control.

Quantifying the Transmission of Foot-and-Mouth Disease Virus in Cattle via a Contaminated Environment

Effective control of a disease relies on comprehensive understanding of how transmission occurs, in order to design and apply effective control measures. Foot-and-mouth disease virus (FMDV) is primarily spread by direct contact between infected and naive individuals, although the high levels of virus shed by infected animals mean that virus can also be spread through contact with contaminated environments. Using a series of transmission experiments, we demonstrate that environmental transmission alone would be sufficient to sustain an outbreak. Key observations include that a risk of transmission exists before clinical signs of foot-and-mouth disease (FMD) are apparent in cattle and that survival of virus in the environment extends the transmission risk period. This study highlights the role a contaminated environment can play in the transmission of FMDV and presents approaches that can also be applied to study the transmission of other pathogens that are able to survive in the environment.

Indirect transmission via a contaminated environment can occur for a number of pathogens, even those typically thought of as being directly transmitted, such as influenza virus, norovirus, bovine tuberculosis, or foot-and-mouth disease virus (FMDV). Indirect transmission facilitates spread from multiple sources beyond the infectious host, complicating the epidemiology and control of these diseases. This study carried out a series of transmission experiments to determine the dose-response relationship between environmental contamination and transmission of FMDV in cattle from measurements of viral shedding and rates of environmental contamination and survival. Seven out of ten indirect exposures resulted in successful transmission. The basic reproduction number for environmental transmission of FMDV in this experimental setting was estimated at 1.65, indicating that environmental transmission alone could sustain an outbreak. Importantly, detection of virus in the environment prior to the appearance of clinical signs in infected cattle and successful transmission from these environments highlights there is a risk of environmental transmission even before foot-and-mouth disease (FMD) is clinically apparent in cattle. Estimated viral decay rates suggest that FMDV remained viable in this environment for up to 14 days, emphasizing the requirement for stringent biosecurity procedures following outbreaks of FMD and the design of control measures that reflect the biology of a pathogen.

Experimental Infection of Foot and Mouth Disease in Indian Sheep and Goats

Foot-and-mouth disease (FMD) is an economically important contagious disease of livestock mainly cattle, buffalo, sheep, goats, and pig. There is limited data available on pathogenesis of foot and mouth disease in goats. In the study, the sheep and goats were infected experimentally with a serotype O foot-and-mouth disease virus by different challenge routes. The sheep and goats challenged by coronary band route and coronary band and intra-dermo-lingual route exhibited FMD clinical signs at 2-5 days post challenge. Whereas intra-dermo-lingual challenged sheep and goats did not exhibit FMD clinical signs. Live virus could be isolated from blood of infected sheep and goats at 2-5 days post challenge. Viral RNA could be detected from blood of infected sheep and goats at 1-10 days post challenge. The neutralizing antibody titre was detected at 10 days post challenge and maintained up to 35 days post challenge in all infected sheep and goats. Non structural protein (NSP) antibodies were detected as early as 5-10 days post challenge and remain positive up to 35 days post challenge in the infected sheep and goats. In conclusion, the pathogenesis of sheep and goats with serotype O foot and mouth disease virus by different challenge routes could be demonstrated.

Foot-and-Mouth Disease Space-Time Clusters and Risk Factors in Cattle and Buffalo in Bangladesh

Foot-and-mouth disease (FMD) is highly endemic in Bangladesh. Using passive surveillance data (case records from all 64 districts of Bangladesh, 2014–2017) and district domestic ruminant population estimates, we calculated FMD cumulative incidence per 10,000 animals at risk per district, conducted cluster (Moran’s spatial autocorrelation and scan statistics) and hotspot analysis (local indicator of spatial association statistic), created predictive maps and identified risk factors using a geographically weighted regression model. A total of 548,817 FMD cases in cattle and buffalo were reported during the four-year study period. The highest proportion (31.5%) of cases were reported during the post-monsoon season, and from Chattogram (29.2%) division. Five space-time clusters, 9 local clusters, and 14 hotspots were identified. Overall, higher cumulative incidences of FMD were consistently predicted in eastern parts of Bangladesh. The precipitation in the pre-monsoon season (p = 0.0008) was positively associated with FMD in Bangladesh. Results suggest climate plays an important role in the epidemiology of FMD in Bangladesh, and high risk zones exist. In a resource limited-setting, hotspots and clusters should be prioritized for vaccination coverage, and surveillance for FMD should be targeted in eastern areas of Bangladesh and during the post-monsoon season.

Multilevel model for airborne transmission of foot-and-mouth disease applied to Swedish livestock

The foot-and-mouth disease is an ever-present hazard to the livestock industry due to the huge economic consequences following an outbreak that necessitates culling of possibly infected animals in vast numbers. The disease is highly contagious and previous epizootics have shown that it spreads by many routes. One such route is airborne transmission, which has been investigated in this study by means of a detailed multilevel model that includes all scales of an outbreak. Local spread within an infected farm is described by a stochastic compartment model while the spread between farms is quantified by atmospheric dispersion simulations using a network representation of the set of farms. The model was applied to the Swedish livestock industry and the risk for an epizootic outbreak in Sweden was estimated using the basic reproduction number of each individual livestock-holding farm as the endpoint metric. The study was based on comprehensive official data sets for both the current livestock holdings and regional meteorological conditions. Three species of farm animals are susceptible to the disease and are present in large numbers: cattle, pigs and sheep. These species are all included in this study using their individual responses and consequences to the disease. It was concluded that some parts of southern Sweden are indeed preconditioned to harbor an airborne epizootic, while the sparse farm population of the north renders such events unlikely to occur there. The distribution of the basic reproduction number spans over several orders of magnitudes with low risk of disease spread from the majority of the farms while some farms may act as very strong disease transmitters. The results may serve as basic data in the planning of the national preparedness for this type of events.

Quantification of the sensitivity of early detection surveillance

Early detection surveillance is used for various purposes, including the early detection of non‐communicable diseases (e.g. cancer screening), of unusual increases of disease frequency (e.g. influenza or pertussis outbreaks), and the first occurrence of a disease in a previously free population. This latter purpose is particularly important due to the high consequences and cost of delayed detection of a disease moving to a new population. Quantifying the sensitivity of early detection surveillance allows important aspects of the performance of different systems, approaches and authorities to be evaluated, compared and improved. While quantitative evaluation of the sensitivity of other branches of surveillance has been available for many years, development has lagged in the area of early detection, arguably one of the most important purposes of surveillance. This paper, using mostly animal health examples, develops a simple approach to quantifying the sensitivity of early detection surveillance, in terms of population coverage, temporal coverage and detection sensitivity. This approach is extended to quantify the benefits of risk‐based approaches to early detection surveillance. Population‐based clinical surveillance (based on either farmers and their veterinarians, or patients and their local health services) provides the best combination of sensitivity, practicality and cost‐effectiveness. These systems can be significantly enhanced by removing disincentives to reporting, for instance by implementing effective strategies to improve farmer awareness and engagement with health services and addressing the challenges of well‐intentioned disease notification policies that inadvertently impose barriers to reporting.

The Carrier Conundrum; A Review of Recent Advances and Persistent Gaps Regarding the Carrier State of Foot-and-Mouth Disease Virus

The existence of a prolonged, subclinical phase of foot-and-mouth disease virus (FMDV) infection in cattle was first recognized in the 1950s. Since then, the FMDV carrier state has been a subject of controversy amongst scientists and policymakers. A fundamental conundrum remains in the discordance between the detection of infectious FMDV in carriers and the apparent lack of contagiousness to in-contact animals. Although substantial progress has been made in elucidating the causal mechanisms of persistent FMDV infection, there are still critical knowledge gaps that need to be addressed in order to elucidate, predict, prevent, and model the risks associated with the carrier state. This is further complicated by the occurrence of a distinct form of neoteric subclinical infection, which is indistinguishable from the carrier state in field scenarios, but may have substantially different epidemiological properties. This review summarizes the current state of knowledge of the FMDV carrier state and identifies specific areas of research in need of further attention. Findings from experimental investigations of FMDV pathogenesis are discussed in relation to experience gained from field studies of foot-and-mouth disease.

Impact of foot-and-mouth-disease on goat behaviour after experimental infection with serotype SAT1 virus

Infectious diseases and parasitic infestations can cause a set of non-specific clinical signs, such as increased body temperature and resting, and a decrease in food intake. These physiological and behavioural changes have an adaptive function facilitating defences against the pathogen and to support immune functions. These so-called' sickness behaviours' can also be used as an early detection tool for disease. Foot-and-mouth disease (FMD) still causes great economic losses in endemic countries, especially to smallholder farmers. The aim of this study was to determine if behavioural changes in goats can be used as an early indicator of FMD virus (FMDV) infection. The efficacy of a Southern African Territories (SAT) FMD vaccine was studied on forty South African indigenous goats. Changes in daily activities (resting, feeding, walking), as well as social behaviours (social resting, social feeding, dominance behaviours) were recorded and then compared over time and between clinically affected and unaffected goats. Pedometers were used to estimate average daily steps and to compare between groups of study animals. Eleven goats developed clinical signs of FMD, as well as non-FMD related sicknesses during the course of the study. Overall walking and resting behaviours were not significantly affected by the presence of FMD related clinical signs (p > 0.05). However, during the time of FMDV infection, social resting increased significantly (p < 0.001). Although goats developed FMD lesions on lips and tongues, percentage of time feeding was not affected (p = 0.762), suggesting that the study goats did not perceive the oral lesions as an important disturbance. Similarly, the number of steps did not consistently decrease in the presence of FMD-associated foot lesions. When affected by non-FMD related sicknesses, animals did not have an overall reduction in the time spent feeding (p = 0.867). However, goats affected with non-FMD conditions reduced the amount of social feeding (p = 0.002), potentially avoiding energetically costly competition at the feeding points. Overall, goats affected with FMD did not show more sickness behaviour, suggesting that FMDV infection in goats might not lead to obvious and therefore, easily detectable behavioural changes. This might have implications for farmers and animal health personnel, as individual goats infected with FMDV might be undetected within a flock due to the absence of obvious sickness behaviours, and the virus can therefore be spread more easily between herds through animal movements.

Virulence beneath the fleece; a tale of foot-and-mouth disease virus pathogenesis in sheep

Foot-and-mouth disease virus (FMDV) is capable of infecting all cloven-hoofed domestic livestock species, including cattle, pigs, goats, and sheep. However, in contrast to cattle and pigs, the pathogenesis of FMDV in small ruminants has been incompletely elucidated. The objective of the current investigation was to characterize tissue- and cellular tropism of early and late stages of FMDV infection in sheep following three different routes of simulated natural virus exposure. Extensive post-mortem harvest of tissue samples at pre-determined time points during early infection (24 and 48 hours post infection) demonstrated that tissues specifically susceptible to primary FMDV infection included the paraepiglottic- and palatine tonsils, as well as the nasopharyngeal mucosa. Additionally, experimental aerosol inoculation of sheep led to substantial virus replication in the lungs at 24-48 hours post-inoculation. During persistent infection (35 days post infection), the paraepiglottic- and palatine tonsils were the only tissues from which infectious FMDV was recovered. This is strikingly different from cattle, in which persistent FMDV infection has consistently been located to the nasopharyngeal mucosa. Analysis of tissue sections by immunomicroscopy revealed a strict epithelial tropism during both early and late phases of infection as FMDV was consistently localized to cytokeratin-expressing epithelial cells. This study expands upon previous knowledge of FMDV pathogenesis in sheep by providing detailed information on the temporo-anatomic distribution of FMDV in ovine tissues. Findings are discussed in relation to similar investigations previously performed in cattle and pigs, highlighting similarities and differences in FMDV pathogenesis across natural host species.

Review on Outbreak Dynamics, the Endemic Serotypes, and Diversified Topotypic Profiles of Foot and Mouth Disease Virus Isolates in Ethiopia from 2008 to 2018

Foot and mouth disease (FMD) endemicity in Ethiopia's livestock remains an ongoing cause for economic concern, with new topotypes still arising even in previously unaffected areas. FMD outbreaks occur every year almost throughout the country. Understanding the outbreak dynamics, endemic serotypes, and lineage profiles of FMD in this country is very critical in designing control and prevention programs. For this, detailed information on outbreak dynamics in Ethiopia needs to be understood clearly. In this article, therefore, we review the spatial and temporal patterns and dynamics of FMD outbreaks from 2008 to 2018. The circulating serotypes and the topotypic profiles of the virus are also discussed. FMD outbreak data were obtained from; reports of MoARD (Ministry of Agriculture and Rural Development)/MoLF (Ministry of livestock and Fishery, NVI (National Veterinary Institute), and NAHDIC (National Animal Health Diagnostic and Investigation Center); published articles; MSc works; PhD theses; and documents from international organizations. To effectively control and prevent FMD outbreaks, animal health agencies should focus on building surveillance systems that can quickly identify and control ongoing outbreaks and implement efficient preventive measures.

The Risk of Foot and Mouth Disease Transmission Posed by Public Access to the Countryside During an Outbreak

During the 2001 UK FMD outbreak, local authorities restricted rural access to try to prevent further disease spread by people and animals, which had major socio-economic consequences for rural communities. This study describes the results of qualitative veterinary risk assessments to assess the likelihood of different recreational activities causing new outbreaks of foot and mouth disease, as part of contingency planning for future outbreaks. For most activities, the likelihood of causing new outbreaks of foot and mouth disease is considered to vary from very low to medium depending on the control zone (which is based on distance to the nearest infected premises), assuming compliance with specified mitigation strategies. The likelihood of new outbreaks associated with hunting, shooting, stalking, and equestrian activities is considered to be greater. There are areas of significant uncertainty associated with data paucity, particularly regarding the likelihood of transmission via fomites. This study provides scientific evidence to underpin refinement of rural access management plans and inform decision-making in future disease outbreaks.

History and epidemiology of foot-and-mouth disease in Afghanistan: a retrospective study

BACKGROUND

Foot and mouth disease (FMD) is endemic in Afghanistan with serotypes O, A and Asia 1 being prevalent. A retrospective study of data collected through passive surveillance of outbreaks of FMD in Afghanistan from 1995 to 2016 was undertaken to determine the temporal and spatial distribution of FMD in the country.

RESULTS

A total of 4171 outbreaks were reported between 1995 and 2008 with a strong correlation between the number of outbreaks and the number of provinces (r = 0.85, s = 68.2, p < 0.001); and between the number of outbreaks and the number of districts containing infected animals (r = 0.68, s = 147.8, p = 0.008). Of 7558 samples collected from livestock originating from 34 provinces in 2009, 2011 and 2013-2015, 54.1% were test positive (FMDV 3ABC-trapping ELISA) and the prevalence varied significantly between years (χ2 = 263.98, df = 4, P < 0.001). Clinically suspected cases were reported in 2016 with a substantial positive correlation (r = 0.70, P < 0.001) between the number of districts with cases and the number of reported cases. Serotype O was the predominant serotype detected during the study period, although serotypes A and Asia1 were also detected. Cattle were involved in all outbreaks in the study period and infections were detected in all years of the study in Hirat province in the north-west (bordering Iran), Nangarhar province in the east (bordering Pakistan) and Kabul province in the centre of the country.

CONCLUSIONS

The current paper was the first analysis of existing data focusing on the spatiotemporal distribution of FMD in Afghanistan. The findings from this study provide valuable direction for further research to understand the epidemiology of FMD and its control in Afghanistan.

Evaluating the utility of national-scale data to estimate the local risk of foot-and-mouth disease in endemic regions

Knowledge of the distribution of foot-and-mouth disease (FMD) is required if control programmes are to be successful. However, data on the seroprevalence and incidence of affected villages in developing countries with endemic disease are scarce. This is partly due to resource constraints as well as the logistical challenges of conducting intensive surveys and diagnostic testing in remote locations. In this study, we evaluated the performance of low resolution national-scale data against high resolution local survey data to predict the FMD serological status of 168 villages in the Mandalay and Sagaing Regions of central Myanmar using both logistic regression and random forest modelling approaches. Blood samples for ELISA testing were collected from approximately 30 cattle per village in both the 6 to 18 month age range and in the over 18 month age range to distinguish between recent and historical exposure, respectively. The results of the animal level tests were aggregated to the village level to provide the outcome of interest (village positive or not positive for FMD), and three explanatory data sets were constructed: using only nationally available data, using only data collected by survey and using the combined survey and nationally available data. The true seroprevalence of FMD at the village level was 61% when only young animals were included, but increased to 87% when all animals were included. The best performing model was a logistic regression model using the combined national and survey data to predict recent infection in villages. However, this still incorrectly classified 40% of villages, which suggests that using national-level data were not reliable enough for extrapolating seroprevalence in regions where conducting detailed surveys is impractical. Other methods for collected data on FMD such as the use of local reporting should be explored.

Serological and phylogenetic characterization of foot and mouth disease viruses from Uganda during cross-sectional surveillance study in cattle between 2014 and 2017

Here, we report the results of a cross-sectional study designed to monitor the circulation and genetic diversity of foot and mouth disease virus (FMDV) in Uganda between 2014 and 2017. In this study, 13,614 sera and 2,068 oral-pharyngeal fluid samples were collected from cattle and analysed to determine FMDV seroprevalence, circulating serotypes and their phylogenetic relationships. Circulation of FMDV was evidenced by the detection of antibodies against non-structural proteins of FMDV or viral isolations in all districts sampled in Uganda. Sequence analysis revealed the presence of FMDV serotypes A, O, SAT 1 and SAT 2. FMDVs belonging to serotype O, isolated from 21 districts, were the most prevalent and were classified into six lineages within two East African topotypes, namely EA-1 and EA-2. Serotype A viruses belonging to the Africa G-I topotype were isolated from two districts. SAT 1 viruses grouped within topotypes I and IV and SAT 2 viruses within topotypes VII, IV and X were isolated from six and four districts respectively. Phylogenetic analysis of SAT 1 and SAT 2 sequences from cattle clustered with historical sequences from African buffalo, indicating possible interspecies transmission at the wildlife-livestock interface. In some cases, Uganda viruses also shared similarities to viral strains recovered from other regions in East Africa. This 3-year study period provides knowledge about the geographical distribution of FMDV serotypes isolated in Uganda and insights into the genetic diversity of the multiple serotypes circulating in the country. Knowledge of circulating FMDV viruses will assist in antigenic matching studies to devise improved FMDV control strategies with vaccination and vaccine strain selection for Uganda.

The epidemiology of foot-and-mouth disease outbreaks and its history in Iraq

Background and Aims:

Foot-and-mouth disease (FMD) is reported in Iraq since 1937 and occurs as a devastating seasonal epidemic. This study intended to explore the epidemiology of FMD in Iraq during 2011-2016, through assessment of outbreak reports among cow, buffalo, and small ruminants (sheep and goat) in 15 Iraqi governorates except for Kurdistan region.

Materials and Methods:

The reported data regarding FMD cases were collected from veterinary hospitals in 15 Iraqi governorates and were analyzed.

Results:

The results revealed annual FMD outbreaks in cow, buffalo, and small ruminants in Iraqi governorates with variability in the numbers of the infected and dead animals. The total number of infected animals increased in 2016 compared to 2015 due to the illegal importation of FMD-infected cows at the end of 2015. The prevalence rates of FMD were 68.7%, 46.6%, and 30.3% in cattle, buffalo, and small ruminants, respectively, in 2016, while this was 18.4%, 19.9%, and 17.3%, respectively, in 2015.

Conclusion:

This study approved the reemergence and endemic nature of FMD in Iraqi livestock. Prompt procedures and a new future strategy need to be implemented to control the increasing incidences of FMD in Iraq.

A review of foot-and-mouth disease virus (FMDV) testing in livestock with an emphasis on the use of alternative diagnostic specimens

Foot-and-mouth disease virus (FMDV) remains an important pathogen of livestock more than 120 years after it was identified, with annual costs from production losses and vaccination estimated at €5.3–€17 billion (US$6.5–US$21 billion) in FMDV-endemic areas. Control and eradication are difficult because FMDV is highly contagious, genetically and antigenically diverse, infectious for a wide variety of species, able to establish subclinical carriers in ruminants, and widely geographically distributed. For early detection, sustained control, or eradication, sensitive and specific FMDV surveillance procedures compatible with high through-put testing platforms are required. At present, surveillance relies on the detection of FMDV-specific antibody or virus, most commonly in individual animal serum, vesicular fluid, or epithelial specimens. However, FMDV or antibody are also detectable in other body secretions and specimens, e.g., buccal and nasal secretions, respiratory exhalations (aerosols), mammary secretions, urine, feces, and environmental samples. These alternative specimens offer non-invasive diagnostic alternatives to individual animal sampling and the potential for more efficient, responsive, and cost-effective surveillance. Herein we review FMDV testing methods for contemporary and alternative diagnostic specimens and their application to FMDV surveillance in livestock (cattle, swine, sheep, and goats).

Seroprevalence and risk factors for peste des petits ruminants and selected differential diagnosis in sheep and goats in Tanzania

Introduction: Livestock husbandry is critical for food security and poverty reduction in a low-income country like Tanzania. Infectious disease is one of the major constraints reducing the productivity in this sector. Peste des petits ruminants (PPR) is one of the most important diseases affecting small ruminants, but other infectious diseases may also be present.

Objective: The objective of this study was to determine the seroprevalence and risk factors for exposure to PPR, contagious caprine pleuropneumonia (CCPP), foot-and-mouth disease (FMD), bluetongue (BT), and bovine viral diarrhoea (BVD) in sheep and goats in Tanzania.

Methods: Serum samples were collected in 2014 and 2015, and analysed using enzyme-linked immunosorbent assays to detect antibodies to the five pathogens.

Results and discussion: This is the first description of seroprevalence of FMD and BT among small ruminants in Tanzania. Risk factor analysis identified sex (female) (OR for 2014: PPR: 2.49, CCPP: 3.11, FMD: 2.98, BT: 12.4, OR for 2015: PPR: 14.1, CCPP: 1.10, FMD: 2.67, BT: 1.90, BVD: 4.73) and increasing age (>2 years) (OR for 2014: PPR: 14.9, CCPP: 2.34, FMD: 7.52, BT: 126, OR for 2015: PPR: 8.13, CCPP: 1.11, FMD: 2.98, BT: 7.83, BVD: 4.74) as risk factors for exposure to these diseases.

First detection of foot-and-mouth disease virus O/Ind-2001d in Vietnam

In recent years, foot-and-mouth disease virus (FMDV) serotype O, topotype Middle East-South Asia (ME-SA), lineage Ind-2001d has spread from the Indian subcontinent to the Middle East, North Africa, and Southeast Asia. In the current report, we describe the first detection of this lineage in Vietnam in May, 2015 in Đắk Nông province. Three subsequent outbreaks caused by genetically related viruses occurred between May–October, 2015 after which the virus was not detected in clinical outbreaks for at least 15 subsequent months. The observed outbreaks affected (in chronological order): cattle in Đắk Nông province, pigs in Đắk Lắk province and Đắk Nông province, and cattle in Ninh Thuận province. The clinical syndromes associated with these outbreaks were consistent with typical FMD in the affected species. Overall attack rate on affected premises was 0.85 in pigs and 0.93 in cattle over the course of the outbreak. Amongst 378 pigs at risk on affected premises, 85 pigs died during the outbreaks; there were no deaths among cattle. The manner in which FMDV/O/ME-SA/Ind-2001d was introduced into Vietnam remains undetermined; however, movement of live cattle is the suspected route. This incursion has substantial implications for epidemiology and control of FMD in Southeast Asia.

Establishment of an on-site diagnostic procedure for detection of orf virus from oral lesions of Japanese serows (Capricornis crispus) by loop-mediated isothermal amplification

Orf virus infection has been prevalent continuously in the population of wild Japanese serows (Capricornis crispus), goat-like grazing cloven-hoofed mammal species that live mainly in mountainous areas of Japan. Currently, definitive diagnosis of infection requires time-consuming laboratory work. To diagnose rapidly on-site, we developed a field-friendly procedure for the detection of orf virus from oral cavity lesions. DNA was extracted from goat saliva spiked with orf virus as a proxy for Japanese serows by a commercial kit without the use of electricity, and the quality of the extracted DNA was evaluated by conventional polymerase chain reaction (PCR). Extracted DNA was amenable to DNA amplification, the same as when extracted in a laboratory. Next, to find optimal conditions for DNA amplification by loop-mediated isothermal amplification (LAMP), Bst and Csa DNA polymerases and 3 colorimetric indicators for visual diagnosis, hydroxy naphthol blue (HNB), malachite green and D-QUICK, were compared using a portable cordless incubator. The combination of Bst or Csa DNA polymerase with HNB was found to be easiest for visual diagnosis by the naked eye, and viral DNA was successfully amplified from all orf virus strains used. These results suggest that the procedure established here can work completely on-site and can be useful for definitive diagnosis and differentiation of orf virus infection in Japanese serows in remote mountainous areas.

Efficiency of the Clinical Veterinary Diagnostic Practices and Drug Choices for Infectious Diseases in Livestock in Bangladesh

As in most low-income countries, adequate laboratory facilities are not available in Bangladesh to assist veterinarians in diagnosing animal diseases. We aimed to determine the efficiency of veterinary diagnoses for two common ruminant diseases in Bangladesh: Peste des petits ruminants (PPR) and foot-and-mouth disease (FMD). We conducted the study from May 2009 to August 2010 in three government veterinary hospitals where veterinarians collected samples from sick livestock and recorded the presumptive diagnosis on the basis of clinical presentations. Samples were tested for PPR and FMD using real-time RT-PCR. We estimated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the presumptive diagnoses when compared to laboratory tests. We tested 539 goats for PPR and 340 cattle and goats for FMD. Our results indicate that the veterinarians' presumptive diagnoses were different from laboratory findings for both PPR (P < 0.05) and FMD (P < 0.05). The overall sensitivity of the presumptive clinical diagnoses was 54% (95% CI: 47-61%) while specificity was 81% (95% CI: 78-84%) compared to real-time RT-PCR tests. The kappa value obtained in our validation process for PPR (kappa: 0.25) and FMD (kappa 0.36) indicated a poor performance of the presumptive diagnoses. Most of the animals (93%) were treated with antibiotics. Our findings indicate that veterinarians can detect animals not infected with FMD or PPR but miss the true cases. The clinical competency of these veterinarians needs to be improved and access to laboratory diagnostic facilities could help veterinarians to improve the diagnostics and outcomes. The rational use of antibiotics by veterinarians in animals must be ensured.

Seroprevalence of foot and mouth disease virus infection in pigs from Zuru, Nigeria

Aim:

This study was conducted to determine the seroprevalence and distribution of foot and mouth disease virus (FMDV) infection in pigs from Zuru, Kebbi State, Nigeria.

Materials and Methods:

Cross-sectional serological surveys were conducted between May and December 2013 using the immunochromatography assay technique. Structured questionnaires were administered to households identified at pig rearing areas to obtain the population structures and some information on managemental practices.

Results:

A total number of 849 pigs were enumerated at 37 pigs rearing households. Tudun wada had the largest concentration of pigs (237 pigs), while Dabai has the least (38 pigs). A total of 250 blood samples were collected, of which 45 (18%) were positive; Zango has the highest seroprevalence (1.6%), while Dabai recorded the least (0.4%). Based on sex and age, the infection was higher in female (10.4%) and young pigs (11.6%) than male (7.6%) and adult pigs (6.4%), respectively. There was no significant (p>0.05) association between infection and pig rearing areas, sex, and age. Furthermore, none of the 250 pigs examined for classical FMDV lesions was positive.

Conclusion:

The results of this study showed that FMD is an important disease of pigs in the study areas. This result justifies the need for more attention and subsequent molecular study to identify the circulating FMDV in the area, which will help in the implementation of effective control measures.

Prevalence and risk factors for foot and mouth disease infection in small ruminants in Israel

During the last decade, 27% of the foot and mouth disease (FMD) outbreaks in Israel affected small ruminant (SR) farms. FMD outbreaks reoccur in Israel despite vaccination of all livestock and application of control measures. We performed a cross-sectional serological study, aimed at estimating the prevalence of FMD infection in SR in Israel and the possible risk factors for infection. Overall, 2305 samples of adult sheep (n=1948) and goats (n=357) were collected during 2011-14 in two separate surveys. One survey was based on random sampling of intensive management system farms and the other was originally aimed at the detection of Brucella melitensis at extensive and semi-intensive management system farms. Sera were tested by NS blocking ELISA (PrioCHECK(®)). The serological prevalence of antibodies against non structural proteins (NSP) of FMD virus was estimated at 3.7% (95% confidence interval (CI95%)=3.0% -4.5%). Additionally, a significantly lower infection prevalence (p value=0.049) of 1.0% (CI95%=0.1%-3.6%) was found in a small sample (197 sera) of young SR, collected during 2012. The positive samples from adult SR were scattered all over Israel, though two significant infection clusters were found by the spatial scan statistic. Occurrence of an outbreak on a non-SR farm within 5km distance was associated with a fifteen times increase in the risk of FMD infection of SR in the univariable analysis. Yet, this variable was not included in the multivariable analysis due to collinearities with the other independent variables. Multivariable logistic regression modeling found significantly negative associations (P value<0.05) of grazing and being in a herd larger than 500 animals with risk of infection. Grazing herds and herds larger than 500 animals, both represent farms that are intensively or semi-intensively managed. Higher maintenance of bio-safety, fewer introductions of new animals and higher vaccination compliance in these farms may explain their lower risk of infection by FMD virus. We conclude that despite the wide distribution of infection among SR farms, low farm level prevalence indicates that in Israel SR pose only limited role in the transmission and dissemination of FMD. This conclusion may be applicable for other endemic countries in which, similar to Israel, all livestock are vaccinated against FMD.

Profiling oral and digital lesions in sheep in Ireland

BACKGROUND

During the FMD outbreak in Ireland and the UK in 2001, there was significant uncertainty amongstveterinary practitioners and government veterinary inspectors surrounding the clinical diagnosis of FMD insheep. This situation was complicated by reports of idiopathic oral ulcers that closely resembled FMD ongross appearance which at that time were referred to as ovine mouth and gum obscure disease.

METHODS

A field and abattoir study was carried out to determine the frequency, appearance and significance of oraland digital lesions in sheep in Ireland. A total of 3, 263 sheep were examined in 22 flocks, including 1, 969lambs and 1, 294 adults. A further 2,403 animals were examined by abattoir inspections. Animals bearing lesions of interest were identified, samples of the lesions were taken and subsequently examined by bacteriology, electron microscopy, serology, immunohistochemistry and histopathology.

RESULTS

Forty four oral and 20 digital lesions were identified and characterised. Oral lesions were recorded mostfrequently in lambs, where the most common cause was orf virus infection. The majority of the oral lesions recorded in the adults was idiopathic and consistent with a diagnosis of idiopathic oral ulceration. A variety of digital lesions was observed, consistent with scald, foot-rot and contagious ovine digital dermatitis (CODD). All of the animals with lesions were seronegative to FMD virus (FMDV).

CONCLUSIONS

There was no difficulty in differentiating these lesions from those caused by FMDV on the basis of flockhistory and careful clinical examination.

Assessing the delay to detection and the size of the outbreak at the time of detection of incursions of foot and mouth disease in Australia

The time delay to detection of an outbreak of an emergency animal disease directly affects the size of the outbreak at detection and the likelihood that the disease can be eradicated. This time delay is a direct function of the efficacy of the surveillance system in the country involved. Australia has recently completed a comprehensive review of its general surveillance system examining regional variation in both the behaviour of modelled outbreaks of foot and mouth disease and the likelihood that each outbreak will be detected and reported to government veterinary services. The size of the outbreak and the time delay from introduction to the point where 95% confidence of detection was reached showed significant (p < 0.05) regional variation with the more remote northern areas experiencing smaller outbreaks that are less likely to spread and less likely to be reported to government services than outbreaks in the more developed southern areas of Australia. Outbreaks in the more densely populated areas may take up to 43 days until a 95% confidence of detection is achieved and at that time, the outbreak may involve up to 53 farms.

Clinical and virological dynamics of a serotype O 2010 South East Asia lineage foot-and-mouth disease virus in sheep using natural and simulated natural inoculation and exposure systems

Within-host infection dynamics of a recent field isolate of foot-and-mouth disease virus (FMDV), serotype O, topotype South East Asia, lineage Myamar'98 were evaluated in sheep using four different systems for virus exposure. Two novel, simulated natural, inoculation systems consisting of intra-nasopharyngeal (INP) deposition and aerosol inoculation were evaluated in comparison with two conventional systems: coronary band inoculation and direct contact exposure. All four exposure systems were efficient in generating consistently severe, generalized FMD with synchronous clinical characteristics within exposure groups, indicating that this Myanmar98 strain is highly virulent in sheep. Clinical and virological dynamics were similarly rapid following INP- and coronary band inoculation, with both systems leading to significantly earlier detection of virus shedding when compared to aerosol inoculation and contact exposure. The data presented herein support application of the two optimized simulated natural inoculation systems as valid alternatives to conventionally used exposure systems for studies of FMDV pathogenesis and vaccinology in sheep. Furthermore, the data suggest that targeted exposure of the ovine pharynx is highly efficient for generating consistent FMDV infection, which supports critical involvement of this anatomic region as a site of primary virus replication in sheep.

Transmission characteristics and optimal diagnostic samples to detect an FMDV infection in vaccinated and non-vaccinated sheep

We wanted to quantify transmission of FMDV Asia-1 in sheep and to evaluate which samples would be optimal for detection of an FMDV infection in sheep. For this, we used 6 groups of 4 non-vaccinated and 6 groups of 4 vaccinated sheep. In each group 2 sheep were inoculated and contact exposed to 2 pen-mates. Viral excretion was detected for a long period (>21 days post-inoculation, dpi). Transmission of FMDV occurred in the non-vaccinated groups (R0=1.14) but only in the first week after infection, when virus shedding was highest. In the vaccinated groups no transmission occurred (Rv<1, p=0.013). The viral excretion of the vaccinated sheep and the viral load in their pens was significantly lower than that of the non-vaccinated sheep. FMDV could be detected in plasma samples from 12 of 17 infected non-vaccinated sheep, for an average of 2.1 days, but in none of the 10 infected vaccinated sheep. In contrast, FMDV could readily be isolated from mouth swab samples from both non-vaccinated and vaccinated infected sheep starting at 1-3 dpi and in 16 of 27 infected sheep up till 21 dpi. Serologically, after 3-4 weeks, all but one of the infected sheep were detected using the NS-ELISA. We conclude that vaccination of a sheep population would likely stop an epidemic of FMDV and that the use of mouth swab samples would be a good alternative (instead of using vesicular lesions or blood samples) to detect an FMD infection in a sheep population both early and prolonged after infection.

[Validation of a real time RT-PCR assay to detect foot-and-mouth disease virus and assessment of its performance in acute infection]

A specific real time reverse transcription polymerase chain reaction (RT-PCRrt) for the detection of foot-and-mouth disease virus was validated using the LightCycler thermocycler 2.0 and its reagents as recommended by the World Organization for Animal Health and was assessed for the detection of the virus in acute infection of cattle experimentally vaccinated and challenged with virus A Argentina/2001 or A24 Cruzeiro. The technique proved to be robust, showing coefficients of variation lower than 4% for different ARN extractions, days or repetitions and was able to detect up to 0,4 TCID 50%, and/or up to 100 RNA molecules. In probang samples, diagnostic sensitivity was 93.1 (95% CI 86.5-96.6) and diagnostic specificity 100 (95% CI 96.3-100). The results of the challenge in vaccinated or multivaccinated bovines showed that although there were high levels of clinical protection in the vaccinated group, FMDV could be detected in all challenged groups. However, detection was 100 times lower in immunized animals.