Commercial Indirect ELISA Research Articles

Epidemiological surveillance of myxoma virus in European hares (Lepus europaeus) in the Iberian Peninsula: First evidence of infection by the emerging ha-MYXV.

We investigated the circulation of myxoma viruses (MYXV) in European hare (Lepus europaeus) populations from Spain. A total of 140 individuals were sampled through passive and active surveillance from 2018 to 2024. Myxoma virus DNA was confirmed in two out of 114 (1.8 %, CI 95 %=0.2-6.2) hares analysed by PCR. One was infected with the classic MYXV strain, and the other with the recombinant ha-MYXV strain. This is the first report of ha-MYXV infection in a European hare. A commercial indirect ELISA detected antibodies against MYXV in 3.2 % (4/126; CI 95 %=0.9-7.9) of animals tested. Both molecular and serological results suggest occasional transmissions of MYXV from sympatric European rabbits (Oryctolagus cuniculus) and/or Iberian hares (Lepus granatensis) to European hares. These sporadic infections appear to be scattered across time and space, predominantly in areas where lagomorph species overlap. Because European hares appear to be immunologically naïve to MYXV, another recombination event could have a significant impact on populations, similar to what occurred with Iberian hares. This study highlights the importance of enhancing our understanding of MYXV epidemiology in wild lagomorph species through large-scale monitoring efforts.

Spatial distribution of Q fever in sheep and goats of selective villages of Punjab Province, Pakistan

AbstractThis study aimed to assess the geographical distribution of Q fever in sheep and goats in different areas of Punjab, Pakistan. Three hundred blood samples of small ruminants including sheep and goats were collected from 60 villages of three districts (Okara, Kasur, and Pakpattan) of Punjab Province Pakistan and tested for the detection of anti-Coxiella burnetii antibodies using a commercial Indirect ELISA kit. Data related to sampling location, host species, gender, age, and GPS coordinates were collected for spatial analysis. A surface plot was created using inverse distance weight (IDW) by interpolation of the Aeronautical Reconnaissance Coverage Geographic Information system (Arc GIS). The district Kasur (14%) and the tehsil Chunian (24%) had the most prominent Q fever prevalence in both species. No ovine males were seropositive but 19.2% of male goats were seropositive. No samples of sheep younger than 1 year were found seropositive. Gender in sheep and age in goats have to be considered as significant risk factors based on multiple logistic regression analysis. Based on spatial analysis, seropositivity for C. burnetii antibodies was more likely observed in villages of tehsil Kasur, Pattoki, Okara, Depalpur, and Renala Khurd in the case of goats while in case of sheep villages of tehsil Chunian, Renala Khurd and Pakpattan. The main outcome of this study is that Q fever-specific antibodies of C. burnetii are prevalent in the goat and sheep populations of the study area and we have identified potential risk zones. The findings of this study can be used for the control of Q fever in small ruminants of the study area to minimize the risk of this zoonosis in other animals and the associated human population.

Serological evidence of Erysipelothrix rhusiopathiae antibodies in wild boars (Sus scrofa) in Poland.

This study aimed to evaluate the seroprevalence of Erysipelothrix rhusiopathiae among wild boars inhabiting Poland. Serum samples were collected from 281 wild boars of varying ages (juveniles, adolescents and adults) and subjected to testing using a commercial indirect ELISA assay. The prevalence of E. rhusiopathiae antibodies was notably high, reaching 75.1% overall and varying slightly across different age categories (90.0% in juveniles, 70.7% in adolescents and 79.6% in adults). Despite these variations, no statistically significant differences were observed among age groups (P-value > 0.05). The elevated prevalence of E. rhusiopathiae identified in this study underscores the significance of wild boars as natural reservoirs of this bacterium. Further investigations are warranted to identify the risk factors associated with disease transmission to other species, including humans.

Seroepidemiology of Coxiella burnetii in Domestic and Wild Ruminant Species in Southern Spain.

The European Food Safety Authority has recently listed Q fever as a priority for setting up a coordinated surveillance system. Although Spain is the country with the highest human incidence of the disease in the European Union, updated data on Coxiella burnetii in ruminants are still limited. A total of 780 serum samples from small ruminants and 605 sera from wild ruminants were collected in the Mediterranean ecosystems of southern Spain during the period 2015-2023. Anti-C. burnetii antibodies were detected using a commercial indirect ELISA. The overall individual seroprevalence in the small ruminants was 49.1% (383/780; 95% CI: 45.6-52.6). Antibodies against C. burnetii were identified in 40.0% (156/390) of sheep and in 58.2% (227/390) of goats. At least one seropositive animal was observed in all sheep (100%) and in 92.3% of goat flocks. The species (goat) and the existence of reproductive disorders in primiparous females were potential risk factors for C. burnetii exposure in small ruminant farms. In the wild ruminants, the overall seroprevalence against C. burnetii was 1.5% (9/605; 95% CI: 0.8-2.8). Anti-C. burnetii antibodies were found in 1.8% (2/110) of mouflon, 1.5% (6/390) of red deer, and 1.0% (1/105) of Iberian ibex. The high exposure of the small ruminants to C. burnetii, particularly in goats, detected in the present study is of animal and public health concern. Our results denote that wild ruminants only play a minor role in the epidemiology of this bacterium in southern Spain and suggest an independent epidemiological cycle of C. burnetii in domestic and wild ruminant species in the study area.

Simultaneous Presence of Antibodies against Five Respiratory Pathogens in Unvaccinated Dairy Calves from South-Western Poland.

Bovine Respiratory Disease (BRD) poses a significant threat to cattle welfare worldwide, affecting their respiratory system and causing substantial economic losses. BRD is multifactorial in nature. This research aimed to investigate the serological profile of calves for the five main bovine respiratory pathogens. Serum samples were collected from dairy calves aged 7-12 months that had never been vaccinated against tested pathogens and had recently shown signs of BRD. A total of 4095 calves from 650 dairy herds located in south-western Poland were examined. The Commercial Indirect Respiratory ELISA Kit Multiplexed-Double well-BIO K 284/5 (Bio-X Diagnostics, Rochefort, Belgium) was used to determine the presence of antibodies against BVDV, BoAHV1, BRSV, BPIV3, and M. bovis. The presence of antibodies against at least one of the tested pathogens was found in 306 (47.08%) herds. The overall prevalence of antibodies was as follows: BoAHV1 21.54%, BVDV 32.0%, BRSV 34.15%, BPIV3 34.31%, and M. bovis 31.38%. The strongest correlation was between BRSV antibodies positive sera and BPIV3 antibodies positive sera. Among the five pathogens tested, antibodies to BVDV, BRSV, BPIV3, and M. bovis were most commonly detected simultaneously. The results of this study indicate the need for preventive measures against these pathogens in the studied region.

Toxoplasma gondii in Wild Boars (Sus scrofa) in Germany: Serological Screening from Thuringia.

Game meat is an important source of meat borne parasitic infections. Due to its omnivorous diet, the wild boar is an important host of zoonotic parasites such as Toxoplasma gondii. T. gondii can cause severe to fatal disease in immunosuppressed patients, as well as congenital disorders in foetus and neonates. Consumption of undercooked infected meat is a main source of T. gondii infection. Information about the risk of toxoplasmosis through game meat is scarce. We collected serum samples from 42 wild boars from the federal state of Thuringia (Germany) between December 2017 and February 2018. Identification of anti-T. gondii IgG antibodies was conducted using a commercial indirect ELISA kit. Seropositivity was confirmed in 18 of the 42 samples (37.50%). From these, the highest seroprevalence was found in adult animals. This study joins another single database from wild boars in Brandenburg. The necessity of a country-wide database regarding T. gondii prevalence in wild boar and other game meat is pivotal for a profound risk analysis with its consequential impact in future mean hygiene policies.

Prevalence, Risk Factors, and Relationship between Reproductive Performance and the Presence of Antibodies against Coxiellosis in Dairy Farm Milk Tanks in the Northwest of Spain

Q fever is a zoonotic disease that has been associated with reproductive problems in animals. As there is little epidemiological data regarding the distribution and risk factors of this disorder in cattle, the objective of this study was to evaluate the prevalence of Coxiella burnetii among dairy herds in the northwest of Spain, and to determine the on-farm risk factors associated with the disease and its effects on reproductive performance. Bulk tank milk (BTM) samples were collected from 262 commercial dairy herds from A Coruña, Lugo, and Pontevedra provinces. Data about location, mean age, and herd management features were obtained. A commercial indirect ELISA kit was used to determine the presence of antibodies against C. burnetii in BTM samples. The relationship between seropositivity to C. burnetii and the risk factors was checked using a Pearson’s χ2 test and a classification tree analysis. In addition, a one-way ANOVA test and the Mann–Whitney U test were used to check the impact of seropositivity to C. burnetii on reproductive performance. A total of 60.1% of the farms tested positive for coxiellosis, the herd size, the external purchase of livestock, and the geographical area were identified as the main risk factors. Conception rate and first-service conception rate were significantly lower (p < 0.05) in positive farms (37.1 and 32.9%) compared to negative farms (39.8 and 36.1%). Similarly, positive farms had significant higher incidence of endometritis (13.7% vs. 11.2%, p < 0.05). Consequently, a high seropositivity and slightly negative effects of coxiellosis on reproductive performance were observed, which intensifies the need for further research, including the identification an active infection in positive herds and the characterization of the genotype.

Seroprevalence and associated risk factors for Toxoplasma gondii in water buffaloes (Bubalus bubalis) in Egypt

Toxoplasmosis is a parasitic disease caused by Toxoplasma gondii and affecting all warm-blooded animals. The available data about the epidemiological situation of T. gondii in water buffaloes in Egypt are scarce. Thus, a cross-sectional study was conducted to determine the seroprevalence of T. gondii in water buffaloes in three Egyptian governorates and to evaluate the associated risk factors for the infection. A total of 430 sera samples were examined using commercial Indirect ELISA Multi-species kit. The overall seroprevalence rate of T. gondii in examined water buffaloes was 7.4 %, and the highest rate (9.3 %) was found in Kafr ElSheikh governorate. Multivariate logistic regression analysis showed that adult buffalo (OR = 7.10; 95 % CI: 0.87–57.68; P = 0.067) and small herds (OR = 8.42; 95 % CI: 1.07–66.02; P = 0.043) were more likely than young buffalo and large herds to become infected with T. gondii. Moreover, the risk of buffaloes contracting T. gondii infection was higher in winter and especially among animals contacted with cats. It is necessary to identify risk factors in order to determine what mitigation, control, and prevention strategies to implement in order to reduce, control, and prevent T. gondii infection in domestic animals, which will in turn reduce human infection with the disease.

Seroprevalence and risk factors associated with bovine viral diarrhoea virus in Turkey.

Bovine viral diarrhoea virus (BVDV) is an infectious agent that is extensively observed worldwide and is among the crucial pathogens of the cattle industry. BVDV infection causes gastrointestinal and respiratory diseases. This study aimed to determine the seropositivity and associated potential risk factors for the risk assessment of BVDV infection in the dairy cattle population in the Aegean Region of Turkey. In this cross-sectional study, 552 serum samples were collected between August 2018 and September 2019 from 48 herds that were not vaccinated against BVDV. Farmers were interviewed using a questionnaire on potential BVDV risk factors. BVDV-specific antibodies in serum samples were detected using a commercial indirect-ELISA kit. The herd-level and animal-level prevalence of BVDV seropositivity was 89.58% (95% CI: 77.83-95.47) and 48.37% (95% CI: 44.23-52.54), respectively. The multivariable logistic regression model analysis demonstrated a positive correlation between BVDV infection and age, common pasture use with small ruminants, the use of natural insemination, and history of respiratory and/or reproduction problems. The results of this study showed that BVDV infection is common in dairy herds in the Aegean Region. The risk assessment would aid the implementation of a voluntary control programme for BVDV in this region.

First Seroprevalence Survey of Avian Reovirus in Broiler Breeders Chicken Flocks in Morocco.

Avian reovirus (ARV) is a prevalent infectious agent that has the potential to cause respiratory and gastrointestinal illnesses in poultry, leading to substantial financial losses in the poultry sector. Until now, there have been no investigations conducted to examine the epidemiological status of ARV infections in Morocco. The aim of this study was to investigate the seroprevalence of ARV infections with respect to area, types of chickens (broiler breeder, and broiler), vaccination status, and age of chickens. A total of 826 serum samples were collected from 36 broiler and broiler breeder flocks, with 14 of them being unvaccinated, fromsix different regions of Morocco, namely Casablanca-Settat, Rabat-Salé-Kénitra, Tanger-Tétouan-Al Hoceïma, Oriental, Marrakech-Safi, and Fez-Meknès between 2021 and 2022.These serum samples were screened using a commercial indirect ELISA ARV antibody test kit (IDEXX REO). The study found that all tested flocks were positive for ARV-specific antibodies, indicating that the virus was present in these flocks. Out of the 826 serum samples tested, 782 were positive for ARV-specific antibodies. The overall prevalence of ARV infections in breeder and broiler flocks was calculated to be 94.6% ± 0.78. To summarize, the current study provides evidence of the widespread distribution of ARV infections in Morocco, suggesting that the poultry industry in the country is highly infected with ARV.

Sero-Prevalence and Assessment of Presumed Risk Factors for Bovine Respiratory Syncytial Virus in and Around Sebeta Town, Ethiopia

Bovine respiratory syncytial virus (BRSV) is one of the main causes of severe pneumonia, interstitial edema and emphysema in cattle. A cross sectional study was conducted and 384 serum samples were collected from cattle of different age, sex and breeds including various risk factors for the assessment the disease in and around Sebeta town, Ethiopia, from December 2021 to June 2022. Presence of antibodies against BRSV was analyzed using a commercial indirect ELISA test. Accordingly, at farm level 33 herds were addressed for sampling and 31(93.9% 95% CI: 77.4%-98.6%) were positive with a minimum of one animal. Similarly, of the total 384 samples tested for individual animals 140(36.4% (95%CI: 31.8- 41.4%)) were showed positive. The association of various risk factors with response variable was also analyzed using logistic regression model. Indeed, the result revealed herd size, age and hygienic status were statistically significant (p<0.05). The likelihood of BRSV infection was relatively higher in large herd size (AOR= 3.79; 95% CI=1.35-11.47; p=0. 018) than small herd sizes. The odds of cattle’s exposed for BRSV was also increase with age where 2-5 years (AOR=45.18; 95% CI=19.11-106.78; p<0.001) and above 5 year animals (AOR =55.17; 95% CI 18.76-162.22; p<0.001) were more prone to infection as compared to less than 2 years old calves. Similarly, animals under poor hygienic management were more likely affected with the disease as compared to good hygienic status (AOR=0.35; 95% CI: 0.15-0.84; P=0.0018). All other presumed risk factors (i.e. Sex, BCS, Origin, respiratory problems and access for visitors) for the disease were found statistically insignificant (p>0.05); although there is a remarkable variation between each categories under the variables. In general, the current result finding showed that a wide spread of the disease in the study area and likely in Ethiopia. The risk factors particularly those having significant association with the dependent variables will help to design effective control strategies. Further studies to isolate and characterize the circulating virus and studying its degree of pathogenesis in the study area was highly recommended which enables on the reduction of exposure to the infection through developing effective control and prevention strategies like vaccination.

First seroepidemiological and risk factor survey of avian metapneumovirus circulation in Moroccan broiler farms

Avian metapneumovirus (aMPV) is a highly contagious pathogen for broilers. Its epidemiological aspects remain poorly understood in Morocco. Given that, we carried out a pilot seroepidemiological survey from December 2020 to June 2021 to define aMPV seroprevalence in Moroccan broiler flocks in different bioclimatic zones (humid to sub-humid, semi-arid, arid) during winter and spring. According to these zones, 48 flocks not vaccinated against aMPV were selected using a stratified random sampling model. With a simple random sampling strategy, fifteen to thirty sera per flock were collected then analysed using a commercial indirect ELISA kit (CIVTEST AVI TRT?, HIPRA S.A., Amer, Spain) that was able to titre antibodies against aMPV subtypes A and B. Furthermore, questionnaires were shared with veterinarians in charge of flocks to collect data and analyse it with multivariable logistic regression models to identify risk factors associated with virus circulation. From 1142 sera, 912 tested positive with the ELISA used, showing an overall aMPV seroprevalence of 79.86% in the broilers. The arid zone had the highest seroprevalences: 94.16% during winter and 84.82% during spring. Bioclimate and season seemed to contribute to aMPV seropositivity. Likewise, high stocking densities and poor hygiene scores on farms were proven to predispose birds to seropositivity. Hereby, we show the circulation of aMPV in Moroccan broiler farms is influenced by bioclimate, season, density, and hygiene conditions. The present study is the first serological evidence of aMPV in broilers in the Maghreb region.

Seroprevalence of Bovine Viral Diarrhea Virus and Factors Associated with the Serological Status in Dairy Cattle in Western Region of Thailand

Background: Bovine viral diarrhea virus (BVDV) causes productive losses and reproductive failure in dairy farms. This study defined the seroprevalence and determined the factors associated with BVDV infection in dairy cows in the western region of Thailand. Methods: Blood samples were collected from 732 cows in 30 randomly selected dairy herds. The BVDV antibody was detected using a commercial indirect ELISA kit (IDEXX®BVDV Total Ab, IDEXX Laboratories Inc., Maine, USA). A questionnaire about the herd management was used to collect data via interviews with farm owners. The variables identified by Fisher’s Exact Test (p less than 0.20) were then analyzed using multivariate logistic regression. Result: Individual prevalence of BVDV infection was 36.89% (270/732), while herd prevalence was 93.33% (28/30). Significant risk factors of BVDV based on the univariate analysis were identified as area, herd size, feeding type, history of abortion, pen of calving, biosecurity and pet on farm (p less than 0.05). Biosecurity using no disinfectant (p=0.02) (OR, 1.32; CI 95%, 1.038-1.669), pet on farm (p=0.03) (OR, 4.72; CI 95%, 1.142-19.501) and history of abortion (p=0.00) (OR, 0.02; CI 95%, 0.004-0.140) were significant, based on multivariate regression analysis. Pen of calving (p=0.01) (OR, 0.24; CI 95%, 0.084-0.667) was a protective factor for BVDV infection. BVDV infection in dairy cattle herds was distributed throughout the western region of Thailand.

Retrospective serological and molecular survey of myxoma or antigenically related virus in the Iberian hare, Lepus granatensis.

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 collected over two time periods almost two decades apart, 1994-1999 and 2017-2019 for the presence of antibodies and MYXV-DNA. First, we screened all serum samples using a rabbit commercial indirect ELISA (iELISA) and then tested a subset of these samples in parallel using indirect immunofluorescence test (IFT), competitive ELISA (cELISA) and qPCR targeting M000.5L/R gene conserved in MYXV and ha-MYXV. The cut-off of iELISA relative index 10=6.1 was selected from a semiparametric finite mixture analysis aiming to minimize the probability of false positive results. Overall, MYXV related-antibodies were detected in 57 hares (12.6%) including 38 apparently healthy hares (n=10, sampled in 1994-1999, none MYXV-DNA positive, and n=28 sampled in 2017-2019 of which four were also ha-MYXV-DNA positive) and 19 found-dead and ha-MYXV-DNA-positive sampled in 2018-2019. Interestingly, four seronegative hares sampled in 1997 were MYXV-DNA positive by qPCR, the result being confirmed by sequencing of three of them. For the Iberian hares hunted or live trapped (both apparently health), 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=.009). Within the second period, seroprevalence was significantly higher in 2019 compared to 2017 (24.7vs 1.7% considering all the sample, p=.007), and lower during the winter than the autumn (p<.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 1996, they also show an increase in seroprevalence in 2018-2019. The remote contact with MYXV may have occurred with strains that circulated in rabbits, or with unnoticed strains already circulating in Iberian hare populations. This work strongly suggests the infection of Iberian hares with MYXV or an antigenically related virus, at least 20 years before the severe virus outbreaks were registered in 2018.

Spatiotemporal monitoring of myxomatosis in European wild rabbit (Oryctolagus cuniculus) in Spanish Mediterranean ecosystems.

A long-term active epidemiological surveillance programme was conducted to determine seroprevalence to myxoma virus (MYXV), infection prevalence and spatiotemporal patterns and factors associated with MYXV circulation in wild rabbits (Oryctolagus cuniculus) in Spanish Mediterranean ecosystems. A total of 2376 animals were sampled over four study periods: 2009-2012 (P1), 2012-2015 (P2), 2015-2018 (P3) and 2018-2021 (P4). Antibodies against MYXV were detected by a commercial indirect ELISA in 59.9% (1424/2376; 95% CI: 58.0-61.9) of wild rabbits. At least one seropositive animal was detected on 131 (96.3%) of 136 game estates sampled. MYXV infection was confirmed by PCR in 94 of 1063 (8.8%; 95% CI: 7.3-10.7) wild rabbits. Circulation of the novel recombinant MYXV (ha-MYXV) was not found in wild rabbits analysed during P4. Five statistically significant spatiotemporal clusters of high MYXV seroprevalence were identified using a Bernoulli model: one in P2 and four in P3. A generalized linear mixed model (GLMM) analysis identified sampling season (autumn), age (adult and juvenile), outbreaks of myxomatosis in the month prior to sampling, mean annual temperature, humidity and seropositivity to rabbit haemorrhagic disease virus as factors potentially linked with MYXV seropositivity. GLMM analysis identified outbreaks of myxomatosis in the month prior to sampling, MYXV seropositivity and presence of lesions compatible with myxomatosis as factors associated with MYXV infection. The results indicate high exposure, widespread but non-homogeneous distribution, and endemic circulation of MYXV in wild rabbit populations in southern Spain during the last decade. Prevalence of antibodies against MYXV showed fluctuations both within the year and over the study periods, revealing variations in the immunity of wild rabbit populations in Mediterranean ecosystems that could increase the risk of MYXV re-emergence in immunologically naïve populations. The present study highlights the importance of long-term surveillance to better understand the epidemiology of MYXV in wild lagomorphs.

Study on Seroprevalence and Associated Risk Factors of Newcastle Disease in Smallholder Poultry Farms in Sodo Zuria District, Wolaita Zone, Southern Ethiopia.

Newcastle disease (NCD) is a highly contagious viral disease of poultry and remains a constant threat in poultry farms that causes huge economic losses. The objective of this study was to estimate and assess the seroprevalence and associated risk factors of Newcastle disease in the Sodo Zuria district, southern Ethiopia. A cross-sectional survey followed by a simple random sampling technique was conducted from May to July 2021 on 384 apparently healthy nonvaccinated chickens on 30 smallholder poultry farms using commercial indirect ELISA kits and a questionnaire survey. The data were analyzed by using STATA for windows version 20 and a logistic regression reporting odds ratiowas applied to describe the seroprevalence of Newcastle disease with associated risk factors. The result of the study demonstrates that there was a high seroprevalence 48.7% (n= 187/384) of Newcastle disease in the study district. Information on associated risk factors were assessed using a semistructured questionnaire. The sex of the chicken showed a statistically significant difference (x2 = 4.842; p = 0.028) with the seroprevalence of the disease. The difference in seroprevalence among intensive, semi-intensive, and extensive management system was statistically significant (x2 = 3.84; p = 0.0001). There was also a statistical significant difference (x2 = 2.3854; p = 0.496) in the absence and presence of safe disposal of a dead chicken with the occurence of Newcastle disease. However, no statistically significant difference was observed among age groups (x2 = 4.335; p = 0.114), disinfection of poultry house (x2 = 0.0; p = 0.998), presence and absence of footbath (x2 = 2.969; p = 0.085), the breeds (x2 = 4.490; p = 0.106), type of chicken (x2 = 0.302; p = 0.583), and housing system (x2 = 1.926; p = 0.588). A high seroprevalence without vaccination history showed that the virus was circulating within the poultry. Therefore, further molecular study has to be conducted to identify circulating strains and develop an evidence-based control program.

Producción de antígenos y estandarización de un ELISA casero indirecto para la detección de anticuerpos contra Anaplasma marginale

Serologic tests are important for the detection of specific antibodies against infectious agents. Commercial indirect ELISA are costly and usually as effective as in-house ELISAs. In the present work, it was prepared a batch of Anaplasma marginale crude antigen from infected blood, and tested it against official positive and negative serum controls and compared with an old batch of antigen. The new antigen batch showed an efficiency similar to the old batch. The sensitivity of the test was comparable between the new and old batches. Both, new and old antigen lots are being used at an excess. The new antigen lot is large enough to run thousands of tests at a more affordable price than commercial kits.

Serological Evidence of Q Fever among Dairy Cattle and Buffalo Populations in the Campania Region, Italy.

Due to its economic impact on livestock and its zoonotic effect, Q fever is a public and animal health problem. Information on this infection in Italy is presently supported by reports of reproductive problems in livestock farms and is, therefore, insufficient to properly understand the impact of the disease. This study aimed to describe for the first time the seroprevalence of Q fever in dairy cows and water buffalos in the Campania region (Southern Italy). A total of 424 dairy cattle and 214 water buffalo were tested using a commercial indirect ELISA kit. An overall seroprevalence of 11.7% confirmed the wide distribution of C. burnetii in this region. Several factors were positively associated with higher seroprevalence, such as species (higher in cattle than in water buffalo), age, and coexistence with other ruminant species. The final model of logistic regression included only age (older) and species (cattle), which were positively associated with the presence of Q fever antibodies. Our findings support the widespread presence of Coxiella burnettii in Campania and show a seroprevalence similar to that observed in previous studies in other Italian regions and European countries. Since human cases are typically linked to contact with infected ruminants, there is a need to improve surveillance for this infection.

Associations between management factors and seroprevalence of Mycobacterium avium subsp. paratuberculosis in dromedary camels

Johne’s disease is a chronic infectious granulomatous enteritis caused by Mycobacterium avium subsp. paratuberculosis (MAP) and mainly infect wild and domestic animals. Although MAP infection has been reported worldwide, observational studies on MAP in camels are very scarce. The objective of the present investigation was to determine the herd- and camel-level seroprevalences and management factors associated with MAP seroprevalence in dromedary camels in the Eastern Province, Saudi Arabia. A cross-sectional study with two-stage random sampling was conducted. Serum samples from 391 camels in 67 herds were collected and tested for the presence of MAP antibodies using a commercial indirect ELISA test. The average MAP herd- and camel-level seroprevalences were 40.3% (95% CI: 29.10 – 52.60%) and 16.1% (95% CI: 12.78 – 20.11%), respectively. The herd-level factors showed a greater risk of MAP seropositivity in medium (36 − 75) and larger (>75) size herds compared with small (<36) herds. Furthermore, the risk of MAP seropositivity decreased in herds with calving pens compared to herds without calving pens. The camel-level factors indicated a decrease in seroprevalence of MAP with the age of camels. The present study revealed a high prevalence of MAP in dromedary camels in Eastern Province, Saudi Arabia. The herd-level risk factors for MAP seroprevalence identified in this study will provide the baseline data for developing and implementing a comprehensive control program for MAP in Saudi Arabia.

SEROLOGICAL RESPONSE IN CROSS-BRED HEIFERS IMMUNIZED WITH BRUCELLA ABORTUS STRAIN RB51 VACCINE UNDER SMALLHOLDER DAIRY FARM MANAGEMENT SYSTEM IN BANGLADESH

Background: Brucella abortus live vaccines (strains 19 and RB51) have successfully been used to control bovine brucellosis especially to protect cattle against infection and abortion worldwide. Most of the knowledge of the protective immune response of these vaccines against brucellosis induced by immunization derives from the studies in mice. Some studies on humoral immune response of these vaccines have been studied in bovine and buffaloes and an attempt is made further to evaluate the serological responses of RB51 vaccine in cross-bred heifers of smallholder dairy farms in Bangladesh. Objective: This study was conducted to measure serological responses induced in cross-bred dairy heifers immunized with RB51 Brucella abortus vaccine by using indirect ELISA. Materials and Methods: Five cross-bred (Holstein  Local) heifers were selected for this experiment which aged four months and sero-negative for Brucella infection in smallholder dairy farms in the district of Kushtia. Each of the selected heifer received 2.0 ml imported commercial B. abortus RB51 strain vaccine subcutaneously in the neck region at day 0 and then booster dose at 60 days after the first vaccination with similar dose and route during the period from January to July 2020. Each of the collected serum samples of five heifers at day 0, 7, 14, 21, 28, 60, 90, 120 and 150 was tested to detect the antibody status by using commercial indirect ELISA kit. Results: The serological responses (antibody level) was detected by commercial indirect ELISA OD values in the serum of cross-bred heifers induced by using B. abortus strain RB51 commercial live vaccine resulted 0.097 OD value at 0 day (pre-vaccination) and 0.108 at 7th day of post-immunization. It appears that the OD values in the immunized heifers was started to rise from the first week and it was gradually increased and reached the peak level at 60 days (OD value 0.223). Booster vaccination administered at 60 days was resulted peak antibody level at day 90 (OD value 0.313) but its level was started to decline from 120 days with a highest declined at day 150 (OD value 0.199). Conclusions: Further studies to define the cellular immune response and protection against B. abortus infection are recommended before routine use of the vaccine in cattle in Bangladesh.