The Cambodian government is attempting to mobilise government, donor and private sector funding to implement a coordinated FMD vaccination program (FMDVP). A necessary first step is to convince the farmers of the benefits of participating in and potentially financially supporting this program. Information was collected from 300 farmers in order to estimate the on-farm benefits and costs of their participation in an FMDVP. Implementing a successful vaccination program is difficult, and farmers understand from previous experience that there may be institutional, social, technical and financial constraints which limit its success. A benefit-cost analysis needs to take into account that outbreaks do not occur every year, not all cattle will be successfully vaccinated, not all sick animals successfully treated and sometimes sick animals simply sold. This study sensitises these variables in order to give a realistic estimation of the farmer participation benefits in an FMDVP. A general result is that it is worthwhile for farmers to participate in the FMDVP if there are average annual outbreaks, or at least two major outbreaks, in the ensuing five years. However, the results are influenced by the interaction of vaccination success and treatment success and coverage. Ineffective coverage and poor treatment of sick animals reduce the benefits of an FMDVP. It is also important that farmers do not sell sick stock and, if they do, that they are able to breed replacements rather than purchase replacements. There are many factors in the smallholder cattle farming system that will influence the success of an FMDVP; farmers will only choose to participate if they can be convinced of the short and long-term economic benefits.
Brucellosis is an endemic disease in many developing countries and ranked by the World Health Organization among the top seven “neglected zoonoses”. Although a Palestinian brucellosis control program was launched in 1998, the disease reemerged after 2012. Interestingly, a similar reemerging pattern was reported in the neighboring Israeli regions. The aim of this work was to characterize the reemerging strains and delineate their genetic relatedness. During 2015-2017, blood samples from 1324 suspected patients were analyzed using two serological tests. Seropositive samples were cultured, and their DNAs were analyzed by different genetic markers to determine the involved Brucella species and rule out any possible involvement of the Rev.1 vaccine strain. The rpoB gene was sequenced from 9 isolates to screen for rifampicin-resistance mutations. Multi Locus VNTR Analysis (MLVA-16) was used for genotyping the isolates. The molecular analysis showed that all isolates were B. melitensis strains unrelated to the Rev.1 vaccine. The rpoB gene sequences showed four single nucleotide variations (SNVs) not associated with rifampicin resistance. MLVA-16 analysis clustered the isolates into 22 unique genotypes that belong to the East Mediterranean lineage. Altogether, our findings show that the reemergence of brucellosis was due to B. melitensis strains of local origin, the Palestinian and Israeli control programs’ weaknesses could be a major factor behind the reemergence of the disease. However, other socioeconomic and environmental factors must be investigated. Moreover, strengthening brucellosis control programs and enhancing cooperation between all stakeholders is essential to ensure long-term program outcomes to fight brucellosis.
Food-and-mouth disease (FMD) is endemic in Cambodia. The control program for FMD has relied on vaccination, with poor vaccination uptake by smallholder farmers an increasing concern. A study to improve the understanding of farmer knowledge, attitudes and practices of FMD and FMD vaccination was conducted in two Cambodian provinces. The aim was to identify opportunities to improve the disease control programs provided by both the government and private sectors. The survey comprised 300 smallholder farmers using a one-on-one interview technique. Results identified that over two-thirds of the respondent farmers had not vaccinated their cattle over two years. Of those who did, most cattle were vaccinated either once a year or once every three years. A booster had never been administered. FMD outbreaks occurred every year during the study period, with a morbidity rate of over 30%. Isolation of first infected cattle from the household herd was not practiced, with treatment identified as the first preference intervention. Farmers often assisted other farmers to restrain and treat infected cattle both before (57%) and after (43%) their own cattle were infected. This indicated that most farmers did not practice basic biosecurity measures and chose to report FMD outbreaks to the village animal health workers (VAHW), friends, neighbors, and relatives in preference to government officials. It was concluded that poor knowledge of disease transmission and biosecurity, with low FMD vaccination coverage and a focus on treatment, contribute to regular FMD outbreaks in these communities. Improvement of FMD control requires the cooperation of villagers, VAHWs, and village leaders in disease reporting, with either improved funding of government vaccination services or private FMD vaccination service. Training programs for farmers on disease transmission, and the importance of biosecurity and vaccination, including information on the cost-benefits of treatment versus full fee bi-annual FMD vaccination, are required.
The total impact of the worldwide COVID-19 pandemic is still emerging, changing all relationships as a result, including those with pet animals. In the infection process, the use of Angiotensin-converting enzyme 2 (ACE2) as a cellular receptor to the spike protein of the new coronavirus is a fundamental step. In this sense, understanding which residue plays what role in the interaction between SARS-CoV-2 spike glycoprotein and ACE2 from cats, dogs, and ferrets is an important guide for helping to choose which animal model can be used to study the pathology of COVID-19 and if there are differences between these interactions and those occurring in the human system. Hence, trying to help to answer these questions, we performed classical molecular dynamics simulations to evaluate, from an atomistic point of view, the interactions in these systems. Our results show that there are significant differences in the interacting residues between the systems from different animal species, and the role of ACE2 key residues are different in each system and can assist in the search for different inhibitors for each animal.
Toxoplasma gondii was initially classified in three main lineages related to its virulence: Types I, II and III. The recombination of genes during sexual cycle in felids gut led to more than 200 genotypes, found in ToxoDB database, using 11 RFLP markers. Free-range chickens are good bioindicators of soil contamination with T. gondii oocysts. In this sense, there are systematic reviews regarding data of genetic characterization of this parasite in felines and ruminants, but not in chickens heretofore, what makes this work necessary. A systematic review in the literature was performed with papers published prior to September 21st, 2020. The main inclusion criteria was the presence of T. gondii genotypes, isolated strictly from free-range chickens, in experimental works. Initially, a total of 1,343 studies related to the terms were identified on databases and 30 studies were selected to be systematically reviewed. A total of 561 isolates of T. gondii from 6,356 free-range chickens were analyzed for genotyping, revealing 190 genotypes. ToxoDB #59 and #2 were the most frequent in America, #1 was the most frequent in Africa and 3 atypical isolates from genotype ToxoDB #9 were found in Asia. There is not data from Europe and Oceania. The majority of studies were Brazilian (16/30). A total of 68 RFLP genotypes were recognized among the 561 isolates’ DNAs analyzed from the 30 studies. Some studies show new genotypes never described before, which reinforces the idea that some years from now, even more new genotypes will be isolated, due to progressive genetic recombination. The large amount of undefined genotypes makes it necessary to perform Nested PCR technique when genotyping. Moreover, the lack of data in Continents such as Europe, Asia and Oceania makes it necessary to perform new isolating and genotyping studies in these places.
Anthroponotic cutaneous leishmaniasis (ACL) due to Leishmania tropica is spreading to new areas. Exposure to the vector, Phlebotomus sergenti, is the only proven risk factor. Our objective was to compare the densities and genetic characteristics of P. sergenti populations in two nearby localities in Morocco, one within an ACL endemic area (El Borouj) and another undamaged (Sidi Hajjaj). Statistically significant differences were detected between P. sergenti densities with a higher density of P. sergenti in the endemic town (p≤ 0.032). A different main P. sergenti mitochondrial lineage was evidenced in each one of the 2 localities, and for the first time, the lineage of P. sergenti specimens that are acting as a vector of L. tropica has been identified. Bioclimatic differences were detected between both localities. In conclusion, between an ACL endemic locality and another ACL free there are differences in both the density of P. sergenti and the mitochondrial lineage that may explain the different epidemiological situation. Given that the density of P. sergenti in the locality without ACL cases seems sufficient to allow transmission, the main factor that would justify its ACL undamaged character could be the absence of P. sergenti Lineage IV, which seems to prefer warmer and drier climates.
Worldwide, wild birds are frequently suspected to be involved in the occurrence of outbreaks in captive-bred birds although proofs are lacking and most of the dedicated studies are insufficiently conclusive to confirm or characterize the roles of wild birds in such outbreaks. The aim of this study was to assess and compare, for the most prevalent peridomestic wild birds, the different exposure routes for Avian Influenza and Newcastle disease viruses in conservation breeding sites of Houbara bustards in the United Arab Emirates. To do so, we considered all of the potential pathways by which captive bustards could be exposed to Avian Influenza and Newcastle disease viruses by wild birds, and ran a comparative study of the likelihood of exposure via each of the pathways considered. We merged data from an ecological study dedicated to local wild bird communities with an analysis of the contacts between wild birds and captive bustards and with a prevalence survey of AIV and NDV in wild bird populations. We also extracted data from an extensive review of the scientific literature and by the elicitation of expert opinion. Overall, this analysis highlighted that captive bustards had a high risk of being exposed to pathogens by wild birds. This risk was higher for Newcastle disease virus than Avian influenza virus, and House sparrows represented the riskiest species for the transmission of both viruses through indirect exposure from consumption of water contaminated from the faeces of an infectious bird that got inside the aviary. Thus, this analysis reveals that wild peridomestic birds may play a role in the transmission of avian pathogens to captive bred birds. These results also reaffirm the need to implement sanitary measures to limit contacts between wild and captive birds and highlight priority targets for a thoughtful and efficient sanitary management strategy.
Numerous studies have unsuccessfully tried to unravel the definitive host of the coccidian parasite Besnoitia besnoiti. Cattle infections by B. besnoiti cause a chronic and debilitating condition called bovine besnoitiosis that has emerged in Europe during the last two decades, mainly due to limitations in its control associated to the absence of vaccines and therapeutical tools. Although the exact transmission pathway of B. besnoiti is currently unknown, it is assumed that the parasite might have an indirect life cycle with a carnivore as definitive host. Current lack of studies in wildlife might underestimate the importance of free-living species in the epidemiology of B. besnoiti. Thus, the aim of the present study is to assess the presence of Besnoitia spp. in free-ranging mesocarnivores in Spain. DNA was searched by PCR on faeces collected from wild carnivores as a first approach to determine which species could be considered as potential candidates for definitive hosts in further research. For this purpose, a total of 352 faecal samples from 12 free-living wild carnivore species belonging to the Canidae, Felidae, Herpestidae, Mustelidae, Procyonidae, and Viverridae families were collected in seven Spanish regions. PCR testing showed that Besnoitia spp. DNA was present in four faecal samples from red foxes collected in western Spain, an area with the greatest density of extensively reared cattle and associated to high incidence of bovine besnoitiosis in the country. To date, this is the first report of a Besnoitia besnoiti-like sequence (99.57% homology) from carnivore faeces in a worldwide context. Red foxes might contribute to the epidemiology of B. besnoiti, although further studies, mostly based on bioassay, would be needed to elucidate the accuracy and extent of these interesting findings.
African swine fever (ASF) is one of the most severe infectious diseases of pigs. In this study, a LAMP assay coupled with the CRISPR Cas12a system was established in one tube for the detection of the ASFV p72 gene. The single-strand DNA-fluorophore-quencher (ssDNA-FQ) reporters and CRISPR-derived RNA (crRNAs) were screened and selected for the CRISPR detection system. In combination with LAMP amplification assay, the detection limit for the LAMP-CRISPR assay can reach 7 copies/μl of p72 gene per reaction. Furthermore, this method displays no cross-reactivity with other porcine DNA or RNA viruses. The performance of the LAMP-CRISPR assay was compared with real-time qPCR tests for clinical samples, a good consistency between the LAMP-CRISPR assay and real-time qPCR was observed. In the current study, a LAMP coupled with the CRISPR detection method was developed. The method shed a light on the convenient, portable, low cost, highly sensitive and specific detection of ASFV, demonstrating a great application potential for monitoring on-site ASFV in the field.
African Swine Fever Virus (ASFV) causes a deadly disease of pigs which spread through southeast Asia in 2019. We investigated one of the first outbreaks of ASFV in Lao Peoples Democratic Republic amongst smallholder villages of Thapangtong District, Savannakhet Province. In this study, two ASFV affected villages were compared to two unaffected villages. Evidence of ASFV-like clinical signs appeared in pig herds as early as May 2019, with median epidemic days on 1 and 18 June in the two villages, respectively. Using participatory epidemiology mapping techniques, we found statistically significant spatial clustering in both outbreaks (P < 0.001). Villagers reported known risk factors for ASFV transmission such as free-ranging management systems and wild boar access in all four villages. The villagers reported increased pig trader activity from Vietnam before the outbreaks; however, the survey did not determine a single outbreak source. The outbreak caused substantial household financial losses with an average of 9 pigs lost to the disease, and Monte Carlo analysis estimated this to be USD 215 per household. ASFV poses a significant threat to food and financial security in smallholder communities such as Thapangtong, where 40.6% of the district’s population are affected by poverty. This study shows ASFV management in the region will require increased local government resources, knowledge of informal trader activity and wild boar monitoring alongside education and support to address intra-village risk factors such as free-ranging, correct waste disposal and swill feeding.
This study evaluates through modeling the possible individual and combined effect of three populational parameters of pathogens (reproduction rate; rate of novelty emergence; and propagule size) on the colonization of new host species – putatively the most fundamental process leading to the emergence of new infectious diseases. The results are analyzed under the theoretical framework of the Stockholm Paradigm using IBM simulations to better understand the evolutionary dynamics of the pathogen population and the possible role of Ecological Fitting. The simulations suggest that all three parameters positively influence the success of colonization of new hosts by a novel parasite population but contrary to the prevailing belief, the rate of novelty emergence (e.g. mutations) is the least important factor. Maximization of all parameters result in a synergetic facilitation of the colonization and emulates the expected scenario for pathogenic microorganisms. The simulations also provide theoretical support for the retention of the capacity of fast-evolving lineages to retro-colonize their previous host species/lineage by ecological fitting. Capacity is, thus, much larger than we can anticipate. Hence, the results support the empirical observations that opportunity of encounter (i.e. the breakdown in mechanisms for ecological isolation) is an fundamental determinant to the emergence of new associations - in special of Emergent Infectious Diseases - and the dynamics of host exploration, as observed in SARS-CoV-2. Insights on the dynamics of Emergent Infectious Diseases derived from the simulations and from the Stockholm Paradigm are discussed.
African swine fever (ASF) is a viral disease that affects members of the Suidae family. The notifiable disease is considered a major threat to the pig industry, animal health, and food security worldwide. According to the European Food Safety Authority, ASF virus (ASFV) survival and transmission in feed and feed materials is a major research gap. Against this background, the objective of this study was to determine the survival of ASFV on re-contaminated spray dried porcine plasma (SDPP) when stored at two different temperatures. To this means, commercial SDPP granules were contaminated with high titers of ASFV in a worst-case re-contamination scenario. Three samples per time point and temperature condition were subjected to blind passaging on macrophage cultures and subsequent haemadsorption test to determine residual infectivity. In addition, viral genome was detected by real-time PCR. The results indicate that heavily re-contaminated SDPP stored at 4°C remains infectious for at least five weeks. In contrast, contaminated SDPP stored at room temperature displayed a distinct ASFV titer reduction after one week and complete inactivation after two weeks. In conclusion, the residual risk of ASFV transmission through re-contaminated SDPP is low, if SDPP is stored at room temperature for a period of at least two weeks before feeding.
Introduction: Despite eradication and control measures applied across Europe, bovine tuberculosis (bTB) remains a constant threat. In Belgium, after several years of bTB disease freedom status, routine movement testing, as currently practiced, revealed itself inadequate to detect some sporadic breakdown herds. The aim of this study was to strike the balance between cost and effectiveness of different surveillance system components to identify sustainable alternatives for early detection and substantiation of freedom of bTB while maintaining acceptance of these amongst the different animal health stakeholders. Methods: Stochastic iteration model was built to simulate, first, the expected current surveillance system performance in terms of sensitivity and specificity of detection. These results were then descriptively compared to observed field results. Secondly, the cost and effectiveness of simulated alternative surveillance components were quantified. To measure impact of key assumptions (i.e. regarding diagnostic tests and true prevalence), sensitivity analysis was performed. Results: Discrepancies between the predicted and observed performance of bTB surveillance in Belgium were observed. Secondly, simulated alternatives revealed that targeted IFN-γ as well serological testing with Antibody ELISA towards risk herds would enable increasing the overall cost and effectiveness of the Belgian bTB surveillance system. Sensitivity analysis showed that results remained constant despite modification of some key assumptions. Discussion: Performance of current bTB surveillance system performance in Belgium was questionable. This exercise highlighted that not only sensitivity, but specificity is a key driver for surveillance performance. The quantitative and participative conceptual framework revealed itself a useful tool to allow evidence-based decision making regarding future tuberculosis surveillance in Belgium, as required by the international standards.
Bovine tuberculosis (bTB) challenges intensive dairy production in Ethiopia and implementation of the test and slaughter control strategy is not economically acceptable in the country. Vaccination of cattle with Bacillus Calmette-Guerin (BCG) could be an important adjunct to control, which would require a diagnostic test to differentiate Mycobacterium bovis (M. bovis)-infected and BCG-vaccinated animals (DIVA role). This study describes evaluation of a DIVA skin test (DST) that is based on a cocktail (DSTc) or fusion (DSTf) of specific (ESAT-6, CFP-10 and Rv3615c) M. bovis proteins in Zebu-Holstein crossbred cattle in Ethiopia. The study animals used were 74 calves (35 BCG-vaccinated and 39 unvaccinated) aged less than three weeks at the start and 68 known bTB positive cows. Six weeks after vaccination, the 74 calves were tested with DSTc and the single intradermal cervical comparative tuberculin (SICCT) test. The cows were tested with DSTc and SICCT test. Reactions to DSTc were not observed in BCG-vaccinated and unvaccinated calves while SICCT test reactions were detected in vaccinated calves. DSTc reactions were detected in 95.6% of the cows and single intradermal tuberculin (SIT) positive reactions were found in 98.2% (95% confidence interval, CI, 92.1–100%). The sensitivity of DSTc was 95.6% (95% CI, 87.6–99.1%), and significantly (P<0.001) higher than the sensitivity (75%, 95% CI, 63.0-84.7%) of the SICCT test at 4mm cutoff. DSTf and DSTc reactions were correlated (r = 0.75; 95% CI =0.53–0.88). In conclusion, DSTc could differentiate M. bovis-infected from BCG-vaccinated cattle in Ethiopia. DST had higher sensitivity than the SICCT test. Hence, DSTc could be used as a diagnostic tool for bTB if BCG vaccination is implemented for the control of bTB in Ethiopia and other countries.
The Pigeon circovirus (PiCV) which contains a circular single stranded DNA (approximately 2 kb) belongs to the genus Circovirus and the family Circoviridae. PiCV infections in pigeons (Columba livia) have been reported worldwide. Nowadays, pigeon racing is becoming increasingly popular and considered to be a national sport in China, and even, the greatest competitions of racing pigeons are stake place in China. However, there is no epidemiologic data on PiCV infections among racing pigeons in China. To trace the prevalence, genetic variation and evolution of PiCV in sick and healthy racing pigeons, 622 samples were collected from 11 provinces or municipalities of China from 2016 to 2019. Samples were tested by polymerase chain reaction. The results showed that the positive rate of PiCV was 19.3% (120/622) at the sample level; 59.0% (23/39) at the club level, suggesting that the virus was prevalent in Chinese racing pigeons. A sequence analysis revealed that the cap genes of the PiCV strains identified in our study display high genetic diversity and shared nucleotide homologies of 71.9%–100% and amino acid homologies of 71.7%–100%. 28 and 37 unique amino acid substitutions were observed among the cap proteins and rep proteins of our PiCV strains, respectively. Furthermore, two initiation codons (GTG and ATT) of cap gene were newly found. A cap-gene-based phylogenetic analysis showed that the strains in this study could be further divided into six groups (A, B, C, E, G, H and I) and some of our strains are closely related to worldwide strains from different types of pigeons. A large number of recombination events (31 events) were also detected in the PiCV genomes from Chinese racing pigeons. These findings suggest that PiCV strains circulating in China exhibits higher genetic diversity.
Bovine leptospirosis is a bacterial disease that affects bovine herds, causing economic losses due to reproductive problems, which require expensive treatments. The main source of transmission for cattle is still uncertain, but it has been described that small wild mammals can play an important role in the transmission cycle by being maintenance hosts for the pathogenic species of the bacterium and spreading it through urine. In this study, we characterize possible risk areas for bovine leptospirosis in the state of Veracruz, Mexico; based on the geographical distribution of small wild hosts of Leptospira sp. reported in Mexico in addition with climatic, geographic, land use and human activities variables, and validated risk map with bovine seroprevalence data. We used a generalized linear regression model to understand the association between the appearance of bovine leptospirosis seroprevalences and the favorability of wild hosts of Leptospira sp. as well as environmental variables. The parameterized model explains 13.58% of the variance. The seroprevalence in cattle showed a negative relationship with elevation, geographic length and human population density, and a positive relationship with environmental favorability for the bats reservoirs and favorability for at least one rodent and opossum reservoir. The variation in seroprevalence is mainly explained by a longitudinal gradient (10.4% of the variance) and the favourability for bats (3.0% of the variance). Describing the possible risks of seroprevalence in an important and neglected livestock geographical region, we contribute to the selection of areas of strategies for diagnosis and prevention of this relevant disease.
Peste des petits ruminants (PPR) is a viral transboundary disease of small ruminants that causes significant damage to agriculture. The disease has not been previously registered in the Republic of Kazakhstan (RK). This paper presents an assessment of the susceptibility of the RK territory to the spread of this disease in case of its importation from infected countries. Ordinary Least Squares (OLS) and Geographically Weighted Regression (GWR) models trained on the PPR outbreaks in China were used to rank municipal districts of the RK in terms of the risk of PPR spread. Spatial density of outbreaks was used as a risk indicator while a number of socio-economic, landscape and climatic indicators were considered as explanatory variables. The Exploratory Regression tool was used to reveal a best combination of independent variables based on specified thresholds of R-squared, variables’ multicollinearity and residuals’ normality and autocorrelation. The small ruminants’ density, the maximum green vegetation fraction, the annual mean temperature, the road length and density as well as the cattle density were the most significant factors. Both OLS and GWR demonstrated nearly similar model performance providing a global adjusted R-squared of 0.61. Applied to the RK, the models show the greatest risk of PPR spread in the south-eastern and northern regions of the country, especially within Almaty, Zhambyl, Turkistan, West Kazakhstan and East Kazakhstan regions. As part of the study, a country-wise survey was carried out to collect data on the distribution of livestock population the RK, which resulted in compiling a complete geo-database of small ruminants’ holdings in the country. The research results can be used to form a national strategy for the prevention of the importation and spread of PPR in Kazakhstan through targeted monitoring in high-risk areas.
The 2018 outbreak of myxomatosis in the Iberian hare (Lepus granatensis), has been hypothesized to originate from a species jump of the rabbit-associated myxoma virus (MYXV), after natural recombination with an unknown poxvirus. Iberian hares were long considered resistant to myxomatosis as no prior outbreaks were reported. To provide insights into the emergence of this recombinant virus (ha-MYXV), we investigated serum samples from 451 Iberian hares (88 live captured, 313 hunted and 50 found dead) collected over two time periods, 1994-1999 and 2017-2019, using a rabbit commercial indirect ELISA after validation, and tested different tissues or sera by a qPCR targeting M0005L/R gene conserved in MYXV and ha-MYXV. The cut-off of ELISA Relative Index 10 = 6.1 yielded an estimated positive predictive value of 96.4% (CI95% 82.6-98.0%), by comparison with qPCR positive and negative reference hares. Overall, antibodies were detected in 12.6% (57/451) of the hares tested, of which 40.3% (23/57) were also qPCR positive. Antibodies were found in apparently healthy hares sampled in 1994-1999 (n=10, none MYXV-DNA positive), and in 2017-2019 (n=28, of which 14% were MYXV-DNA positive). For the Iberian hares hunted or live trapped, seroprevalence was significantly higher in 2017-2019 (13.0%, CI95% 9.2-18.2%) than in 1994-1999 (5.4%, CI95% 3.0-9.6%) (p=0.005), and significantly higher in 2019 (p=0.007), being lower during the winter (p<0.001). While our molecular and serological results show that Iberian hares have been in contact with MYXV or an antigenically similar virus at least since 1994, they also show an increase in seroprevalence in 2018-2019. The more remote contact of hares with MYXV may have occurred with strains that circulated in wild rabbit, or unnoticed strains circulating in Iberian hare populations. This work clearly confirms the circulation of MYXV in the Iberian hare ate least 20 years before the severe virus outbreaks observed in 2018.