A retrospective study on the epidemiology of foot-and-mouth disease in Bhutan

Epidemiological investigation of foot-and-mouth disease outbreaks in a Vietnamese bear rescue centre

Foot-and-mouth disease (FMD) outbreaks affecting Asiatic black bears (Ursus thibetanus) and a Malayan sun bear (Helarctos malayanus) were previously reported in 2011 in two housing facilities at a Vietnamese bear rescue centre. In this study, demographic data of all animals housed in the centre at the time of the outbreaks (n = 79) were collected. Blood samples drawn from 23 bears at different timepoints were tested for FMDV-specific antibodies targeting using a non-structural protein (NSP) ELISA and by virus neutralisation test (VNT). The relationship between seroconversion and clinical signs was explored and epidemic curves and transmission diagrams were generated for each outbreak, where FMD cases were defined as animals showing FMD clinical signs. Outbreak-specific attack rates were 18.75 and 77.77%, with corresponding basic reproduction numbers of 1.11 and 1.92, for the first and second outbreaks, respectively. Analyses of risk factors showed that after adjusting for sex there was strong evidence for a decrease in odds of showing clinical signs per year of age. All samples collected from bears before the outbreak tested negative to NSP and VNT. All cases tested positive to VNT following onset of clinical signs and remained positive during the rest of the follow up period, while only 6 out of 17 cases tested positive to NSP after developing clinical signs. Six animals without clinical signs were tested post outbreaks; five seroconverted using VNT and three animals were seropositive using NSP ELISA. This study provides initial epidemiological parameters of FMD in captive bears, showing that FMDV is easily spread between bears in close proximity and can cause clinical and subclinical disease, both of which appear to induce rapid and long-lasting immunity.

Cardiac troponin I as a cardiac biomarker has prognostic and predictive value for poor survival in Egyptian buffalo calves with foot-and-mouth disease

Background and Aim:

Foot-and-mouth disease (FMD) causes huge economic losses in Egypt due to reductions in the production of red meat, milk, and milk by-products and can also lead to myocarditis in young animals. The aim of our study was to evaluate cardiac biomarkers, in particular cardiac troponin I (cTnI), and to reveal the relations of cardiac biomarkers with poor survival in FMD-infected Egyptian buffalo calves.

Materials and Methods:

Forty-two Egyptian buffalo calves were included in this study. The calves were divided into 12 apparently healthy control calves and 30 calves clinically diagnosed with FMD during a disease outbreak in Menofia and Behera Governorates, Egypt. The diseased calves were divided, according to age, into 13 calves <3 months old and 17 calves between 3 and 6 months old. The animals were examined clinically and subjected to analysis of cardiac biomarkers.

Results:

Biochemical analysis revealed significant elevations of cardiac biomarkers, especially creatine kinase myocardial band (CK-MB), lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), cardiac troponin T (cTnT), and cardiac troponin I (cTnI) in FMD-infected calves in comparison with control calves. There was a significant association between cTnI and poor survival in infected calves.

Conclusion:

Cardiac biomarkers could be used as a rapid method for diagnosis of myocarditis induced by FMD in Egyptian buffalo calves. In addition, cTnI is a very sensitive and accurate tool for determining myocardial cell damage in the earlier stages of the disease and a good predictor of poor survival in calves.

Spatial and temporal distribution of lumpy skin disease outbreaks in Uganda (2002-2016)

BACKGROUND

Lumpy skin disease (LSD) is a devastating transboundary viral disease of cattle which causes significant loss in production. Although this disease has been reported in Uganda and throughout East Africa, there is almost no information about its epidemiology, spatial or spatio-temporal distribution. We carried out a retrospective study on the epidemiology of LSD in Uganda between the years 2002 and 2016, using data on reported outbreaks collected monthly by the central government veterinary administration. Descriptive statistics were computed on frequency of outbreaks, number of cases, vaccinations and deaths. We evaluated differences in the number of reported outbreaks across different regions (agro-ecological zones), districts, months and years. Spatial, temporal and space-time scan statistics were used to identify possible epidemiological clusters of LSD outbreaks.

RESULTS

A total of 1161 outbreaks and 319,355 cases of LSD were reported from 55 out of 56 districts of Uganda. There was a significant difference in incidence between years (P = 0.007) and across different regions. However, there was no significant difference in the number of outbreaks per month (P = 0.443). The Central region reported the highest number of outbreaks (n = 418, 36%) followed by Eastern (n = 372, 32%), Southwestern (n = 140, 12%), Northern (n = 131, 11%), Northeastern (n = 37, 3%), Western (n = 41, 4%) and Northwestern (n = 22, 2%) regions. Several endemic hotspots for the circulation of LSD were identified in the Central and Eastern regions using spatial cluster analyses. Outbreaks in endemic hotspots were less seasonal and had strikingly lower mortality and case-fatality rates than the other regions, suggesting an underlying difference in the epidemiology and impact of LSD in these different zones.

CONCLUSION

Lumpy Skin disease is endemic in Uganda, with outbreaks occurring annually in all regions of the country. We identified potential spatial hotspots for LSD outbreaks, underlining the need for risk-based surveillance to establish the actual disease prevalence and risk factors for disease maintenance. Space-time analysis revealed that sporadic LSD outbreaks tend to occur both within and outside of endemic areas. The findings from this study will be used as a baseline for further epidemiological studies for the development of sustainable programmes towards the control of LSD in Uganda.

Spatiotemporal analysis of foot-and-mouth disease outbreaks in the Republic of Kazakhstan, 1955 - 2013

Foot-and-mouth disease (FMD) poses a significant obstacle to international trade and economic development, and for that reason, FMD prevention, control and eradication are major goals guiding animal health policy in most countries. The purpose of this study was to conduct a retrospective spatiotemporal analysis of FMD outbreaks among livestock in the Republic of Kazakhstan (RK) from 1955 to 2013. During that time, several FMD control strategies were implemented in RK, which culminated with the World Organization for Animal Health (OIE) recognition of RK as a country that is FMD-free with partial vaccination (2015). Here, we describe and analyse the changes in spatial and temporal dynamics of FMD under different control strategies that were utilized as the country progressively moved towards eradication of the disease. A total number of 5,260 FMD outbreaks of serotype O and A (including the A₂₂ lineage) were recorded in the cattle, pig and small ruminant populations of RK during that period. We found that outbreaks occurred in spatiotemporal clusters only prior to 1970, which is before ring vaccination around outbreaks was first employed. This finding suggests that ring vaccination substantially reduced local spread and prevented large FMD epidemics in the country. Disease incidence steadily decreased after the implementation of ring vaccination and culling of infected animals, with spatiotemporal clusters only occurring as a result of an introduction of an antigenically distinct variant of serotype A. From 1955 to 1984, FMD outbreaks demonstrated two seasonal peaks of incidence in the spring and fall. In contrast, only the peak in spring was observed between 1984 and 2013. Quantitative knowledge on how different policy and alternative control strategies contributed to RK achieving FMD-free status could improve prospects for continued control in RK and inform control strategies in other FMD-endemic regions.

A cross-sectional survey of population demographics, the prevalence of major disease conditions and reason-specific proportional mortality of domestic cattle in the Kingdom of Bhutan

We describe the population demographics, rudimentary measures of reproductive performance, the prevalence of major disease conditions and reason-specific proportional mortality for cattle owned by villagers in 16 dzongkhags (districts) in Bhutan based on the findings of a cross-sectional study carried out between March 2012 and May 2014. The animal health issues that were of concern for livestock owners are also identified. Study households were selected using a stratified, two-stage cluster design. Districts (dzongkhags) formed the strata. Villages within dzongkhags were the first sampling stage and households within villages the second sampling stage. All cattle within each selected household comprised the study population. Questionnaires were collected from 409 households with 1480 standing cattle. A total of 71.0% (95% CI 67.9%-74.1%) of the standing cattle population were female and the median age of cattle was 5 years (Q25 3 years; Q75 7 years). Exotic breeds of cattle (Jerseys, Brown Swiss, and their crosses) comprised 41.4% of the cattle population with local breeds making up the remainder. Although exotic breeds of cattle had a significantly lower age at first calving (median 4 years) compared to local breeds (median 4.8 years) there was no significant difference in the number of calving events per cow for the two breed groups. Diarrhoea was the most prevalent disease condition with 2.8 (95% CI 1.5-4.6) cases per 100 animals followed by bovine enzootic haematuria with 1.9 (95% CI 1.0-3.3) cases per 100 animals. The most frequently cited cause of death was misadventure (proportional mortality 26.2%, 95% CI 15.7%-39.2%) followed by old age (17.8%, 95% CI 9.5%-29.4%). A lack of access to adequate fodder and pasture was the animal health issue that was cited by interviewees most frequently. We provide no evidence that exotic breeds of cattle have superior reproductive performance compared with local breeds. The major cattle health concern cited by interviewees, lack of access to fodder, is likely to contribute to suboptimal productivity and the relatively high incidence of bovine enzootic haematuria in this population. We propose that a prospective cohort study of Bhutanese cattle is warranted to more fully elucidate factors affecting the productivity and longevity of cattle in Bhutan.

Epidemiology of Foot and Mouth Disease in Ethiopia: a Retrospective Analysis of District Level Outbreaks, 2007-2012

This study aimed at determining the incidence, distribution, risk factors, and causal serotypes of foot and mouth disease (FMD) outbreaks in Ethiopia based on 5 years of retrospective outbreak data (September 2007 until August 2012). District level outbreak data were collected from 115 randomly selected districts using a questionnaire administered to district animal health officers. The national incidence of FMD outbreaks during the study period was 1.45 outbreaks per five district years. Outbreaks were geographically widespread affecting all major regional states in the country and were more frequent in the central, southern, and southeastern parts of the country. Neither long-term nor seasonal trends were observed in the incidence of outbreaks. A mixed effects logistic regression analysis revealed that the type of production system (market oriented system versus subsistence systems), presence of a major livestock market and/or route, and adjacency to a national parks or wildlife sanctuary were found to be associated with increased risk of outbreaks in the districts. FMD virus serotypes O, A, SAT 2, and SAT 1 were identified as the causal serotypes of the outbreaks during the study period. Whereas O was the dominant serotype, SAT 2 was the serotype that showed increase in relative frequency of occurrence. The estimated incidence of outbreaks is useful in assessing the economic impacts of the disease, and the identified risk factors provide important knowledge to target a progressive FMD control policy for Ethiopia.

The role of global trade and transport network topology in the human-mediated dispersal of alien species

More people and goods are moving further and more frequently via many different trade and transport networks under current trends of globalisation. These networks can play a major role in the unintended introduction of exotic species to new locations. With the continuing rise in global trade, more research attention is being focused on the role of networks in the spread of invasive species. This represents an emerging field of research in invasion science and the substantial knowledge being generated within other disciplines can provide ecologists with new tools with which to study invasions. For the first time, we synthesise studies from several perspectives, approaches and disciplines to derive the fundamental characteristics of network topology determining the likelihood of spread of organisms via trade and transport networks. These characteristics can be used to identify critical points of vulnerability within these networks and enable the development of more effective strategies to prevent invasions.

Epidemiology of foot and mouth disease in Karnataka state, India: a retrospective study

A retrospective study on the epidemiology of foot and- mouth disease (FMD) in Karnataka, India between the years 1977 and 2012-13 based on the data collected through passive and active surveillance was undertaken. A total of 11,159 outbreaks with 0.271 million cases of FMD were recorded from 30 different revenue districts of Karnataka. There was a significant difference between the years for the annual incidence of FMD (P = <0.001, F = 19.10) and also between the months (P = <0.001, F = 4.22). Cattle and buffaloes were the predominant species affected being involved in all of the outbreaks reported. A significant correlation was observed between livestock density and the number of outbreaks reported (r = 0.70, p < 0.02), and number of cases (r = 0.76, p < 0.01) for all the agro-climatic zones. The Central dry zone (n = 2257, 19.89 %) reported the highest number of outbreaks followed by the Northern dry zone (n = 1881, 16.58 %) and the Southern transition zone (n = 1761, 15.52 %), and attack rates were concentrated in the North/Northeastern/Central dry and transition zones. A large majority of the outbreaks were caused by serotype O (64.04 %), followed by Asia 1 (19.87 %) and A (12.27 %). Serotype C was not reported since 1993 in the state. In recent years, serotype O has dominated (82.59 %), with the rest of the outbreaks being almost equally caused by A (9.01 %) and Asia 1 (8.40 %). The study highlights the significance of the O serotype and cattle as the main indicator species in the epidemiology of FMD in Karnataka, India. The findings from this study can be used as baseline epidemiological data for further research to identify endemic and epidemic areas for the development of a sustainable programme for the progressive control of FMD in the state of Karnataka as well as other endemic settings.

A retrospective study on the epidemiology of anthrax, foot and mouth disease, haemorrhagic septicaemia, peste des petits ruminants and rabies in Bangladesh, 2010-2012

Anthrax, foot and mouth disease (FMD), haemorrhagic septicaemia (HS), peste des petits ruminants (PPR) and rabies are considered to be endemic in Bangladesh. This retrospective study was conducted to understand the geographic and seasonal distribution of these major infectious diseases in livestock based on data collected through passive surveillance from 1 January 2010 to 31 December 2012. Data analysis for this period revealed 5,937 cases of anthrax, 300,333 of FMD, 13,436 of HS, 247,783 of PPR and 14,085 cases of dog bite/rabies. While diseases were reported in almost every district of the country, the highest frequency of occurrence corresponded to the susceptible livestock population in the respective districts. There was no significant difference in the disease occurrences between districts bordering India/Myanmar and non-border districts (p>0.05). Significantly higher (p<0.01) numbers of anthrax (84.5%), FMD (88.3%), HS (84.9%) and dog bite/rabies (64.3%) cases were reported in cattle than any other species. PPR cases were reported mostly (94.8%) in goats with only isolated cases (5.2%) in sheep. The diseases occur throughout the year with peak numbers reported during June through September and lowest during December through April, with significant differences (p<0.01) between the months. The annual usages of vaccines for anthrax, FMD, HS and PPR were only 7.31%, 0.61%, 0.84% and 11.59% of the susceptible livestock population, respectively. Prophylactic vaccination against rabies was 21.16% of cases. There were significant differences (p<0.01) in the administration of anthrax, FMD and HS vaccines between border and non-border districts, but not PPR or rabies vaccines. We recommend that surveillance and reporting of these diseases need to be improved throughout the country. Furthermore, all suspected clinical cases should be confirmed by laboratory examination. The findings of this study can be used in the formulation of more effective disease management and control strategies, including appropriate vaccination policies in Bangladesh.

Outbreaks of foot-and-mouth disease in Peninsular Malaysia from 2001 to 2007

This is a retrospective study of the outbreaks of foot-and-mouth disease (FMD) in Peninsular Malaysia between 2001 and May 2007. In total, 270 outbreaks of FMD were recorded. Serotype O virus (89.95 %) and serotype A (7.7 %) had caused the outbreaks. Significant differences on the occurrence of FMD were found between the years (t = 5.73, P = 0.000, df = 11), months (t = 4.7, P = 0.000, df = 11), monsoon season (t = 2.63, P = 0.025, df = 10) and states (t = 4.84, P = 0.001, df = 10). A peak of outbreaks observed in 2003 could be due to increased animal movement and the other peak in 2006 could be due to a compromised FMD control activities due to activities on the eradication of highly pathogenic avian influenza. Cattle (86 % of outbreaks) suffered the most. However, no difference in disease occurrence between species was observed. The populations of cattle (r = 0.672, P = 0.023) and sheep (r = 0.678, P = 0.022) were significantly correlated with occurrence of FMD. Movement of animals (66 % of outbreaks) was the main source for outbreaks. A combination of control measures were implemented during outbreaks. In conclusion, the findings of this study show that FMD is endemic in Peninsular Malaysia, and information gained could be used to improve the existing control strategy.

Anthropogenic and environmental risk factors for rabies occurrence in Bhutan

Anthropogenic and environmental factors were assessed as predictors of sub-districts in Bhutan that reported rabies in domestic animals during the period 1996-2009. Rabies surveillance data were retrieved from the Veterinary Information System database. Anthropogenic and environmental information were obtained from public data sources. Using the total number of rabies cases reported in domestic animals, the 205 sub-districts of Bhutan were categorized as those sub-districts that reported rabies and those that did not report rabies (n=146). Logistic regression models were fit to the data and odds ratios and 95% confidence intervals were estimated. Sub-districts that share a border with India (OR 10.43; 95% CI: 4.42-24.64; P<0.001); sub-districts connected by major roads (OR 3.09; 95% CI: 1.24-7.68; P=0.015); and greater human population density (OR 3.26; 95% CI: 1.48-7.21, P=0.003) were significantly associated with a sub-district reporting animal rabies in Bhutan during 1996-2009. Results suggest that human population characteristics play an important role in rabies occurrence.

Serological and clinical surveillance studies to validate reported foot-and-mouth disease free status in Tsirang district of Bhutan

Serological and clinical studies were conducted between March 2009 and August 2010 to validate the foot-and-mouth disease free status of Tsirang district of Bhutan as determined by the country's passive surveillance system. Randomised (first survey) and targeted (third survey) samplings, with subsequent follow-up samplings (second and fourth), were conducted on FMD-susceptible animals to detect the disease at a design prevalence of 25% and 20% at the individual animal-level and village-level, respectively. Sera from cattle, goats, pigs, and sheep were tested for the presence of non-structural protein (NSP) antibodies using two commercial (PrioCHECK(®) FMDV NS and CHEKIT(®)-FMD-3ABC-bo-ov) and one in-house NSP kit (c-ELISA, AAHL, Australia). The overall seropositivity (all species) at the animal-level was 3% (95% CI: 1.7, 4.8) and 3.5% (95% CI: 2.1, 5.4), for the randomised and targeted surveys, respectively. Except for one goat from the first survey, none of the small ruminants and pigs had NSP antibodies. The seropositives from the first and targeted surveys were distributed among 13 and 16 of 20 villages sampled, respectively. All repeat testing from the initial seropositive animals and their herd mates, for both the first and third surveys, were negative in the NSP tests 6-8 months later. Using the hypergeometric exact probability formula for two-stage analyses, the results enabled rejection of the null hypothesis and supported conclusion that the population was free from disease at the minimum expected prevalence of 20% at the 95.53% and 99.46% confidence levels, for the randomised and targeted surveys, respectively. Clinical surveillance also showed absence of disease or clinical signs suggestive of FMD. The few seropositives were likely to be false positives due to factors such as imperfect specificities of the tests and possible NSP-residues in the vaccines. The study has paved the way for initiation of zoning approaches for the progressive control of FMD in Bhutan.

The seroprevalence of foot-and-mouth disease in the sedentary livestock herds in four districts of Bhutan

Cross sectional serological surveys were conducted between March and December 2009 to determine the distribution of foot-and-mouth disease and also to validate the current passive surveillance system in Bhutan. A total of 1909 sera collected from cattle, goats, sheep, and pigs, from 485 herds in 106 villages, were tested using a foot-and-mouth disease non-structural protein 3ABC ELISA. The true prevalence at the animal-level for all species was 15% (95% CI: 13.5, 16.7) using the sensitivity (97.2%) and specificity (99.5%) for cattle. The true prevalence for cattle, goats, sheep and pigs were 17.6 (95% CI: 15.6, 19.5), 11.9% (95% CI: 5.6, 18.3), 11.9% (95% CI: 1.3, 25.1), and 1.9% (95% CI: 0.0, 3.8), respectively. The sub-districts that shared border with India had significantly (p=0.03) higher seroprevalence than the interior sub-districts. Villages located in the sub-tropical zone had significantly (p<0.0001) higher seroprevalence than those located at high altitude zones. Herds with known outbreaks of FMD were 3.6 times more likely (p<0.001) to be seropositive than those with no history of outbreaks of FMD. The study showed the usefulness of population-based serological surveys in detecting circulation of active infection in populations which were, until now, considered to be free of disease based on a passive surveillance system. The study also highlighted the benefits of conducting serological and questionnaire surveys, simultaneously, to ascertain the infection status of herds and animals. Some of the findings from this study could be considered for strengthening of the current FMD control program in Bhutan.