Healthy Herds Research Articles

The Impact of Selective Predation on Host-Parasite SIS Dynamics.

While models of host-parasite interactions are widespread in the theoretical literature, we still have limited understanding of the impact of community dynamics on infectious disease dynamics. When the wider host ecology is taken into account, the underlying inter-species feedbacks can lead to counter-intuitive results. For example, the 'healthy herd' hypothesis posits that the removal of a predator species may not be beneficial for a prey population infected by an endemic disease. In this work, we focus on the effects of including a predator species in a susceptible-infected-susceptible model. Specifically, a key role is played by predator selectivity for either healthy or infected prey. We explored both cases and found important differences in the asymptotic behaviours of the system. Independently from selectivity, large portions of parameter space allow for the coexistence of the three species. However, when predators feed mainly on susceptible prey we find that a fold bifurcation can occur, leading to a region of bi-stability between coexistence and parasite extinction. Conversely, when predator selection is strongly towards infected prey, total prey population density can be maximal when the three species coexist, consistent with the 'healthy herd' hypothesis. Our work further highlights the importance of community interactions to infectious disease dynamics.

Seroprevalence of Senecavirus A in sows and grower-finisher pigs in major swine producing-states in the United States

Senecavirus A (SVA) is a single-stranded RNA virus in the family Picornaviridae. Recently, SVA has been associated with idiopathic vesicular disease and increased neonate mortality outbreaks in the United States, Brazil, China, Colombia, and Thailand, with increasing incidence since 2014. Indirect detection by antibody detection methods, including indirect immunofluorescence assay (IFA), virus neutralization assay, and competitive or indirect enzyme-linked immunosorbent assays (ELISAs), have been reported in clinical and experimental trials. The objective of this study was to determine the seroprevalence of SVA in nonclinical affected herds in the United States. Individual samples were collected from 3654 and 2433 clinically healthy grower-finisher pigs and sows, respectively, from 219 unique commercial swine production sites. SVA seroprevalence was evaluated by SVA rVP1 ELISA and SVA IFA. The estimated seroprevalence for grower-finisher pigs and sows was 12.2% and 34.0%, respectively. The herd prevalence was 42.7% for grower-finisher farms and 75.8% for sow farms. The SVA rVP1 ELISA and SVA IFA exhibited a fair (sows) and moderate (grower-finisher) agreement at the herd level, while a fair agreement was observed at the individual level for both pig categories evaluated. The McNemar’s test was significant at the individual and herd level (p < 0.05). In this study, we demonstrated the presence of SVA IgG antibodies in pigs from clinically healthy grower-finisher and sow herds. These results suggest that SVA is circulating subclinically in sow farms and grower-finisher pig farms in major swine producing-states in the United States.

Prevalence of bovine tuberculosis in buffaloes in Hyderabad and Tando Allahyar districts of Sindh, Pakistan

An investigation in buffaloes was carried out in Hyderabad and Tando Allahyar districts, Sindh province, Pakistan to determine the prevalence of bovine tuberculosis. The buffaloes (n=120) were first screened through single intradermal tuberculin test (SITT), then their sera were used for enzyme-linked immunosorbent assay (ELISA). Attempts were further made to isolate the Mycobacterium bovis organism from the milk samples using traditional culture test. Overall prevalence of 4.16%, 8.33% and 2.5% was recorded by SITT, ELISA and culture test respectively. A somewhat higher prevalence was recorded in Tando Allahyar district (SITT 6.66%; ELISA 10%; culture test 5%) as compared to Hyderabad district (SITT 1.66%; ELISA 6.66%; culture test 0%). Statistical analysis did not show any association (P&gt; 0.05) of herd size, sex, age, milk yield and farming type with the prevalence of the disease. Whereas, SITT showed a significant (P Less than 0.05) association of sex, age and milk yield with the prevalence of the disease in Tando Allayer district. The results of present study revealed that bovine tuberculosis is present in apparently healthy buffalo herds of Hyderabad and Tando Allayer districts. Moreover, infected animals shed the M. bovis pathogen in milk that could be a potential hazard to public health.

Expression of pattern recognition receptors in porcine uterine epithelial cells in vivo and in culture

Preservation of a pathogen free uterine environment is critical for maintaining healthy swine herds with high reproductive performance. Considering that uterine epithelial cells are the most numerous and thus likely point of cellular contact for pathogens in the uterus, we hypothesize that these cells may be critical for activating the immune system to clear uterine infections. Although uterine epithelial cells have not been well characterized in pigs, studies in several other species have shown that these cells express several pattern recognition receptors (PRR) and thus may act as sentinels for the uterine immune response. To characterize PRR expression in the porcine uterine epithelia, we used laser-capture microdissection to isolate epithelial cells lining the porcine uterus to quantify in vivo mRNA expression levels for select PRRs. As well, primary uterine epithelial cells (UECs) were isolated, cultured, polarized and PRR expression was quantified. Immunohistofluorescence and immunofluorescence were used to determine subcellular localization of TLR3, TLR4 and TLR9 in both uterine tissue and in polarized primary UECs. Finally, polarized primary UECs were stimulated with ligands for TLR3, TLR4, TLR9 and NOD2 to determine their functional innate immune response. Uterine epithelial cells (in vivo and in vitro) were shown to express TLR1-7, TLR9, NOD1, NOD2, NLRP3, NLRP6, NLRX1, RIG1, MDA5 and LGP2. Subcellular localization of in vivo and polarized primary UECs exhibited TLR3 and TLR9 localized to the apical cell surface whereas TLR4 was localized to the intracellular space. Polarized primary UECs stimulated with TLR3, TLR4 and TLR9 ligands showed induced secretion of IL-6, IL-13 and IL-10, respectively indicating that these receptors were functional. These results indicate that pig uterine epithelial cells are functional innate immune cells that may act as sentinels to protect against uterine infection.

Characterisation of peripheral blood mononuclear cell populations in periparturient dairy cows that develop metritis

Bacterial contamination of the uterus following calving is ubiquitous in the dairy cow, 40% of cows develop postpartum uterine infection, including metritis. While predisposing factors like twinning and dystocia are associated with metritis, it is unclear why some cows remain healthy following calving and others develop uterine infection, negatively impacting animal health, milk production and economic return. Here, we profiled peripheral blood mononuclear cells of cows before calving and during postpartum metritis. We hypothesized that peripheral blood mononuclear cell function and proportions would be altered during the prepartum period in cows that develop postpartum metritis. Using flow cytometry we observed reduced proportions of peripheral CD3+/CD4+, CD4+/CD62L+, FOXP3+ and CD21+ populations from −10 to 40 days relative to calving associated with metritis, while the proportion of peripheral CD3+/CD4+ lymphocytes were specifically reduced in the prepartum period before the onset of metritis. Peripheral blood mononuclear cells from cows with metritis had a perturbed capacity to secrete IL-1β or IFNγ in response to in vitro stimulus; cells collected during the prepartum period from cows that would go on to develop metritis failed to increase IL-1β secretion in response to stimulation, while IFNγ secretion was altered at calving and postpartum in cows with metritis compared to healthy herd mates. No effect of metritis was observed in the capacity of cows to mount a humoral immune response to antigen administered on the day of calving. The studies discussed here suggest that while minor changes to the prepartum immune system are observed in cows that develop metritis, changes observed in the postpartum period are more prevalent and likely a consequences of disease and not causative. Future studies to modulate the prepartum immune system may help to limit postpartum metritis.

Effects of Environmental and Management-Associated Factors on Prevalence and Diversity of Streptococcus suis in Clinically Healthy Pig Herds in China and the United Kingdom.

Streptococcus suis, a global zoonosis of pigs, shows regional differences in the prevalence of human-associated disease for Asian and non-Asian countries. The isolation rates and diversities of S. suis on tonsils of healthy slaughter pigs in China and the United Kingdom were studied for effects of geography, temperature, pig age, and farm type. Isolates underwent analysis of molecular serotype and multilocus sequence type and virulence-associated genotyping. Although we found no significant difference in positive isolation rates between Chinese and UK farms, the prevalences of serotypes previously associated with human disease were significantly greater in the Chinese collection (P = 0.003). A significant effect of temperature was found on the positive isolation rate of the Chinese samples and the prevalence of human disease-associated serotypes in the UK S. suis population (China, P = 0.004; United Kingdom, P = 0.024) and on the prevalence of isolates carrying key virulence genes in China (P = 0.044). Finally, we found marked diversity among S. suis isolates, with statistically significant temperature effects on detection of multiple strain types within individual pigs. This study highlighted the high carriage prevalence and diversity of S. suis among clinically healthy pig herds of China and the United Kingdom. The significant effect of temperature on prevalence of isolation, human disease-associated serotypes, and diversity carried by individual pigs may shed new light on geographic variations in human S. suis-associated disease.IMPORTANCEStreptococcus suis is a global zoonotic pathogen and also a normal colonizer mainly carried on the tonsil of pigs. Thus, it is important to study the effect of environmental and management-associated factors on the S. suis populations in clinically healthy pigs. In this research, we investigated the similarities and differences between the S. suis populations obtained from different pig ages, seasons, and farm management systems and discovered the relationship between high climatic temperature and the prevalence of S. suis.

PCR Based Approach for Detection of Bovine Babesiosis in Suspected Carrier Cattle and Vector Ticks in Sri Lanka

Purpose: Cattle recovered from clinical babesiosis become carriers for a certain period posing a threat of transmitting the disease to the entire herd. Diagnosis of carrier cattle is important for preventing outbreaks of babesiosis. The objective of the present study therefore, was to establish a sensitive rapid detection method for bovine babesiosis in suspected carrier cattle using nested PCR (nPCR). Research Method: Accordingly, 30 blood samples and ticks were collected from suspected carrier cattle representing two bio-climatic zones of Sri Lanka. Blood samples were analysed by both microscopically and nested nPCR methods for detection of bovine babesiosis. Further ticks were analysed for morphological idenfication using micrscopy and for babesiosis with nPCR. Findings: 47% (14/30) among the investigated samples became positive for the babesia infection with light microscopy, while nPCR analysis diagnosed 90% (27/30) as positive. This indicates that, 43% (13/30) of the animals which appeared to be healthy through routine light microscopical diagnosis were in fact carriers posing a major threat to the healthy herd. Further, according to the results of nPCR, 22% (6/27) of the blood samples were positive only for Babesia bovis infection, 11% (3/27) only for Babesia bigemina infection and 67% (18/27) for mixed infection with both parasites. The dominant tick vector isolated from both zones was Rhiphicephalus microplus. Out of the examined ticks, 21% (5/24) were positive for Babesia bigemina infection. Research limitations: Since the sample size from all sites of both climatic zones were uneven and small, data could not be analysed for statistical significance. Originality/Value: However, the results from this study indicate that nPCR provides a sensitive screening method to detect bovine babesiosis compared to the conventional microscopic analysis.

Microbiota Analysis of an Environmental Slurry and Its Potential Role as a Reservoir of Bovine Digital Dermatitis Pathogens.

At present, very little information exists regarding what role the environmental slurry may play as an infection reservoir and/or route of transmission for bovine digital dermatitis (DD), a disease which is a global problem in dairy herds. To investigate whether DD-related bacteria belong to the indigenous microbiota of the dairy herd environment, we used deep amplicon sequencing of the 16S rRNA gene in 135 slurry samples collected from different sites in 22 dairy farms, with and without DD-infected cows. Both the general bacterial populations and digital dermatitis-associated Treponema were targeted in this study. The results revealed significant differences in the bacterial communities between the herds, with only 12 bacterial taxa shared across at least 80% of all the individual samples. These differences in the herd microbiota appeared to reflect mainly between-herd variation. Not surprisingly, the slurry was dominated by ubiquitous gastrointestinal bacteria, such as Ruminococcaceae and Lachnospiraceae Despite the low relative abundance of spirochetes, which ranged from 0 to 0.6%, we were able to detect small amounts of bacterial DNA from DD-associated treponemes in the slurry. However, the DD-associated Treponema spp. were detected only in samples from herds with reported DD problems. These data indicate that treponemes involved in the pathogenesis of DD are not part of the normal environmental microflora in dairy herds without clinical DD and, consequently, that slurry is not a primary reservoir of infection.IMPORTANCE Bovine digital dermatitis (DD), a dermal disease which causes lameness in dairy cattle, is a serious problem worldwide. To control this disease, the infection reservoirs and transmission routes of DD pathogens need to be clarified. The dairy herd slurry may be a pathogen reservoir of DD-associated bacteria. The rationale for the present study was, therefore, to examine whether DD-associated bacteria are always present in slurry or if they are found only in DD-afflicted herds. The results strongly indicated that DD Treponema spp. are not part of the indigenous slurry and, therefore, do not comprise an infection reservoir in healthy herds. This study applied next-generation sequencing technology to decipher the microbial compositions of environmental slurry of dairy herds with and without digital dermatitis.

Serotypes, virulence genes profiles and antimicrobial resistance patterns of Escherichia coli recovered from feces of healthy lambs in Mexico

Healthy lambs are one of the major reservoirs of Shiga toxin-producing Escherichia coli (STEC) and it is known as the cause of foodborne diseases (FBD). The work objective is to characterize (STEC) isolates obtained from rectal swabs of healthy lambs herds, a total of 183 samples were obtained from sheep production units of the State of Mexico. E. coli isolates were confirmed through the amplification of the uid A gene. antimicrobial sensitivity pattern was determined through Kirby-Bauer (CLSI, 2012) test and the presence stx1, stx2 and eae genes from isolates by multiplex PCR. Serotyping was performed using specific anti-O and anti-H sera (SERUNAM, Mexico) for 185 Somatic and 56 flagellar antigens. 126 isolates biochemically and molecularly identified as E. coli were obtained, of which 80 did not express any virulence factor and 46 expressed at least some (STEC) virulence factor. The highest percentage of E. coli resistance was for tetracycline 48.7% (39/80), followed by nalidixic acid 13.7% (11/80), gentamicin 6.2% (5/80) and Ciprofloxacin 3.7% (3/80). Resistance to amikacin, cefotaxime and ceftazidime were not detected. A frequency of 46 STEC isolates (36.2%) were obtained, of which 28/46 (22.0%) expressed stx1, stx2 3/46 (6.5%), stx1, stx2 13/46 (10.2%) and eae 2/46 (1.6%). Thirty different serotypes were obtained. The three serotypes with the highest number of isolates (four each) were: O76:H19, O118:H27 and O146:H21 which have been identified as a cause of diarrhea in human population. An isolate of serogroup O104 was obtained, with a significant importance for European public health. In virtue of the discovered serotypes and the virulence factors distribution, we can affirm that the obtained isolates from lambs in the State of Mexico are classifiable as atypical STEC of low virulence.

Non-native parasite enhances susceptibility of host to native predators.

Parasites often alter host physiology and behavior, which can enhance predation risk for infected hosts. Higher consumption of parasitized prey can in turn lead to a less parasitized prey population (the healthy herd hypothesis). Loxothylacus panopaei is a non-native castrating barnacle parasite on the mud crab Eurypanopeus depressus along the Atlantic coast. Through prey choice mesocosm experiments and a field tethering experiment, we investigated whether the predatory crab Callinectes sapidus and other predators preferentially feed on E. depressus infected with L. panopaei. We found that C. sapidus preferentially consumed infected E. depressus 3to 1 over visibly uninfected E. depressus in the mesocosm experiments. Similarly, infected E. depressus were consumed 1.2to 1 over uninfected conspecifics in field tethering trials. We evaluated a mechanism behind this skewed prey choice, specifically whether L. panopaei affects E. depressus movement, making infected prey more vulnerable to predator attack. Counter to our expectations, infected E. depressus ran faster during laboratory trials than uninfected E. depressus, suggesting that quick movement may not decrease predation risk and seems instead to make the prey more vulnerable. Ultimately, the preferential consumption of L. panopaei-infected prey by C. sapidus highlights how interactions between organisms could affect where novel parasites are able to thrive.

An Investigation into the Etiological Agents of Swine Dysentery in Australian Pig Herds.

Swine dysentery (SD) is a mucohemorrhagic colitis, classically seen in grower/finisher pigs and caused by infection with the anaerobic intestinal spirochete Brachyspira hyodysenteriae. More recently, however, the newly described species Brachyspira hampsonii and Brachyspira suanatina have been identified as causing SD in North America and/or Europe. Furthermore, there have been occasions where strains of B. hyodysenteriae have been recovered from healthy pigs, including in multiplier herds with high health status. This study investigated whether cases of SD in Australia may be caused by the newly described species; how isolates of B. hyodysenteriae recovered from healthy herds compared to isolates from herds with disease; and how contemporary isolates compare to those recovered in previous decades, including in their plasmid gene content and antimicrobial resistance profiles. In total 1103 fecal and colon samples from pigs in 97 Australian herds were collected and tested. Of the agents of SD only B. hyodysenteriae was found, being present in 34 (35.1%) of the herds, including in 14 of 24 (58%) herds that had been considered to be free of SD. Multilocus sequence typing applied to 96 isolates from 30 herds and to 53 Australian isolates dating from the 1980s through the early 2000s showed that they were diverse, distinct from those reported in other countries, and that the 2014/16 isolates generally were different from those from earlier decades. These findings provided evidence for ongoing evolution of B. hyodysenteriae strains in Australia. In seven of the 20 herds where multiple isolates were available, two to four different sequence types (STs) were identified. Isolates with the same STs also were found in some herds with epidemiological links. Analysis of a block of six plasmid virulence-associated genes showed a lack of consistency between their presence or absence and their origin from herds currently with or without disease; however, significantly fewer isolates from the 2000s and from 2014/16 had this block of genes compared to isolates from the 1980s and 1990s. It is speculated that loss of these genes may have been responsible for the occurrence of milder disease occurring in recent years. In addition, fewer isolates from 2014/16 were susceptible to the antimicrobials lincomycin, and to a lesser extent tiamulin, than those from earlier Australian studies. Four distinct multi-drug resistant strains were identified in five herds, posing a threat to disease control.

Antimicrobial resistance and molecular characterization of virulence genes, phylogenetic groups of Escherichia coli isolated from diarrheic and healthy camel-calves in Tunisia.

This study was conducted to determine the prevalence of virulence genes, serogroups, antimicrobial resistance and phylogenetic groups of Escherichia coli strains isolated from diarrheic and healthy camel calves in Tunisia. From 120 fecal samples (62 healthy and 58 diarrheic camel calves aged less than 3 months), 70 E. coli isolates (53 from diarrheic herds and 17 from healthy herds) were examined by PCR for detection of the virulence genes associated with pathogenic E. coli in animals. A significantly greater frequency of the f17 gene was observed in individual camels and in herds with diarrhea, this gene being found in 44.7% and 41.5% of isolates from camels and herds with diarrhea versus 22.5% and 11.7% in camels (p=0.05) and herds without diarrhea (p=0.02). The aida, cnf1/2, f18, stx2 and paa genes were found only in isolates from camels with diarrhea, although at a low prevalence, 1.8%, 3.7%, 1.8%, 3.7% and 11.3%, respectively. Prevalence of afa8, cdtB, eae, east1, iroN, iss, kpsMTII, paa, sfa, tsh and papC genes did not differ significantly between herds with or without diarrhea. Genes coding for faeG, fanC, f41, estI, estII, CS31a and eltA were not detected in any isolates. All isolates were sensitive to amikacin, chloramphenicol, ciprofloxacin, gentamicin and ceftiofur and the highest frequency of resistance was observed to tetracycline, and ampicillin (52.8% and 37.1% respectively). The phylogenetic groups were identified by conventional triplex PCR. Results showed that E. coli strains segregated mainly in phylogenetic group B1, 52.8% in diarrheic herds and 52.9% in healthy herds.

Brachyspira hyodysenteriae isolated from apparently healthy pig herds following an evaluation of a prototype commercial serological ELISA

Swine dysentery (SD) is a disease mainly of grower/finisher pigs characterised by severe mucohaemorrhagic colitis. The classical aetiological agent is the anaerobic intestinal spirochaete Brachyspira hyodysenteriae, although “Brachyspira hampsonii” and Brachyspira suanatina also cause SD. This study reports on the unexpected isolation of B. hyodysenteriae from pigs in apparently healthy herds that gave positive reactions when tested with a prototype commercial serological ELISA for detecting herds infected with B. hyodysenteriae (Priocheck®Brachyspira porcine Ab ELISA). The ELISA was tested with sera collected at abattoirs from 1770 slaughtered pigs from 30 Australian herds, including 12 with a history of SD and18 that were considered by their consulting veterinarians to be healthy. The latter herds had no history of SD and did not routinely use antimicrobials that may have masked the disease. Based on the recommended ELISA cut-off value, 25 herds were recorded as showing evidence of infection, including 11 of 12 herds that were considered infected by the submitters and 14 of the 18 “healthy” herds. When faecal or colonic wall samples from 11 of the 14 “false positive” herds subsequently were culturing 6–24 months after the original ELISA testing was completed, different strains of B. hyodysenteriae were isolated from six herds, including a high-health status breeding herd. The existence of apparently healthy herds that are colonised by B. hyodysenteriae has major implications for the control of SD. Had the ELISA not been trialled it is unlikely that colonic samples from these herds would have been cultured and the colonisation identified.

Transboundary diseases of animals: Concerns and management strategies

Transboundary animal diseases (TADs) are greatly contagious epidemic diseases that can spread very rapidly, irrespective of national borders. They cause high rates of death and disease in animals, thereby having serious socio-economic and sometimes public health consequences while constituting a steady threat to the livelihoods of livestock farmers. With the development of technology, livestock production has gained an integral position in the national economy, socioeconomic development, poverty alleviation and nutrition supply for human. Livestock farming is one of the important sources of livelihood to rural peoples in Bangladesh. A healthy livestock is pleasure of any country including Bangladesh. However, rapid trend of globalization has brought upon challenges in maintaining healthy herds of livestock. The emerging infections of foreign origin could spread across national geographical borders and cause devastation in livestock population. As a result, there will be an emergence and spread of new disease in the region which was once free from the disease. Regional and international approaches have to be followed, and the FAO and OIE Global framework-TADs initiative provides the suitable concepts and objectives as well as an organizational framework to link international and regional organizations at the service of their countries to better prevent and control the risks on animal and human health and the economic impact of TADs and emerging animal diseases. In this paper, we have summarized the main diseases of livestock that are transboundary in nature, and sum up the challenges and necessary management strategies in controlling the transboundary diseases.Res. Agric., Livest. Fish.3(1): 121-126, April 2016

The influence of the rearing period on intramammary infections in Swiss dairy heifers: A cross-sectional study

Healthy replacement heifers are one of the foundations of a healthy dairy herd. Farm management and rearing systems in Switzerland provide a wide variety of factors that could potentially be associated with intramammary infections (IMI) in early lactating dairy heifers. In this study, IMI with minor mastitis pathogens such as coagulase-negative staphylococci (CNS), contagious pathogens, and environmental major pathogens were identified. Fifty-four dairy farms were enrolled in the study. A questionnaire was used to collect herd level data on housing, management and welfare of young stock during farm visits and interviews with the farmers. Cow-level data such as breed, age at first calving, udder condition and swelling, and calving ease were also recorded. Data was also collected about young stock that spent a period of at least 3 months on an external rearing farm or on a seasonal alpine farm. At the quarter level, teat conditions such as teat lesions, teat dysfunction, presence of a papilloma and teat length were recorded. Within 24h after parturition, samples of colostral milk from 1564 quarters (391 heifers) were collected aseptically for bacterial culture. Positive bacteriological culture results were found in 49% of quarter samples. Potential risk factors for IMI were identified at the quarter, animal and herd level using multivariable and multilevel logistic regression analysis. At the herd level tie-stalls, and at cow-level the breed category “Brown cattle” were risk factors for IMI caused by contagious major pathogens such as Staphylococcus aureus (S. aureus). At the quarter-level, teat swelling and teat lesions were highly associated with IMI caused by environmental major pathogens. At the herd level heifer rearing at external farms was associated with less IMI caused by major environmental pathogens. Keeping pregnant heifers in a separate group was negatively associated with IMI caused by CNS. The odds of IMI with coagulase-negative staphylococci increased if weaning age was less than 4 months and if concentrates were fed to calves younger than 2 weeks. This study identified herd, cow- and quarter-level risk factors that may be important for IMI prevention in the future.

A minireview on epidemiological studies for livestock disease investigation

The livestock rearing system in our country is slowly getting shifted from backyard farming as an addendum to agriculture farming to full fledged scientific rearing. It is being viewed as a separate business with good global marketing potential. In this scenario, it is necessary to have a healthy disease free herd, which calls for an early disease detection and diagnosis. To achieve this a systematic study of diseases in the population is necessary. Such a study i.e., epidemiology, is essential to target the global market for the livestock produce and products. This paper reviews the various procedures that can be adopted for livestock disease investigation which will be approved by the scientific community.

Address the Public Health and Food Security Concerns of Babesiosis Through Molecular Detection of Babesia Bovis in Suspected Carrier Cattle of Selected Localities in Sri Lanka

Emergence of babesiosis in both public health and food security concern in global perspectives cannot be ignored. The dairy farming plays an important role in food industry that, fulfilling the protein requirement through producing both milk and meat. The farming operations may get hampered due to non-infectious and infectious diseases. Infectious diseases also cause huge production losses in all farming operations in time to time. Babesiosis becomes a major concern in public health and animal production specialists in recent years both locally and internationally due to severity of out breaks, carrier animals and zoonotic nature. Babesiosis as an emerging zoonotic disease and also causing heavy production losses due to the both clinical diseases and carrier animals. Babesia parasites, mainly Babesia bovis and B. bigemina, are tick-borne hemoparasites inducing bovine babesiosis in cattle globally. Babesiosis is known to occur in tropical and subtropical regions of the world and it is one of the major constraints to the livestock industry which adversely affects economic return and food security by reducing milk, meat production and if not treated leads to the death of the animal. Babesia parasites are considered to be endemic in central Sri Lanka and the prevalence of babesiosis is high in other areas. Carrier cattle infected with babesiosis have low number of parasites in circulation. Babesiosis is difficult to detect and is a challenge to conventional diagnostic methods. However, diagnosis of carrier animals in herd is important for preventing outbreaks by transmission through vector ticks to healthy animals and for obtaining epidemiological data of the disease. Here, we have conducted nested PCR detection of Babesia bovis in carrier cattle (Jersey crosses, Friesian crosses and Australian milking zebu) of selected localities of Sri Lanka. For this study, 30 blood samples were collected from suspected carrier cattle and analyzed using light microscopy and nested PCR. Screening by light microscope indicated that 47% of the samples to be positive. PCR analysis of samples diagnosed 80% as positive. Hence, 33% of the animals appeared to be healthy through routine light microscope diagnosis were in fact carriers posing a threat for the healthy herd population. The high prevalence of babesiosis in carrier cattle in Sri Lanka emphasized that island-wide control and prevention programs against bovine babesiosis are needed to minimize the financial burden caused by the parasites to reduce to production losses. This preliminary study on molecular detection of Babesia bovis in selected localities offers a rapid and efficient screening method for suspected carrier herds while providing new avenues to minimize losers incurred in milk production due to unidentified carrier animals.

Predators reduce Batrachochytrium dendrobatidis infection loads in their prey

Summary Disease ecologists and wildlife managers are increasingly interested in understanding how predators regulate infection in prey populations. The healthy herds hypothesis suggests that predators may decrease infection prevalence by decreasing overall population size, reducing density‐dependent transmission and culling infected individuals from a population. While this model incorporates density‐mediated indirect interactions (DMIIs), it does not incorporate the potential role of trait‐mediated indirect interactions (TMIIs). Using wood frog tadpoles (Lithobates sylvatica), we examined whether predator cues could alter the prevalence and intensity of infection by the fungal pathogen Batrachochytrium dendrobatidis [Bd] and whether both stressors could alter the host's life history traits. Exposure to predator cues caused tadpoles to have reduced Bd infection loads, potentially as a result of stress‐induced immunoenhancement. Tadpoles exposed to Bd had faster development than tadpoles not exposed to Bd, but they did not differ in survival or growth. This suggests that, in this life stage of this species, Bd infection does not have fitness costs. These data suggest that the trait‐mediated effects of predators on infection may alter epidemiological outcomes of Bd exposure.

Analysis of knowledge and adoption level of the dairy farmers regarding clean milk production (CMP) practices

The milk quality is determined by aspects of composition and hygiene of milk, where breeding, feeding, management of healthcare, fodder production, and many such facts mainly influence the compositional quality. Dairy farmer is the key client in this process, who decides the quality of milk from feeding of the milch animal to dairy product supply chain. This study was conducted to know the level of knowledge and adoption of dairy farmers regarding clean milk production practices. Rajasthan state was selected purposively for this study, where 120 dairy farmers from the milk shed area of four districts milk union were selected. The results of the study revealed that 55.84 per cent of the dairy farmers had medium level of knowledge in various aspects of CMP, followed by 33 and 20 per cents of them having low and high level of knowledge, respectively. They had highest knowledge in ‘Housing’ [Knowledge Index (KI) =85.83], followed by ‘Milking’ (KI=76.66). However, they had poor knowledge in ‘Cleaning of animal’ (KI=50.41) and ‘Cooling of milk’ (KI=57.91). It was observed that 71.67 per cent of the dairy farmers had medium level of adoption in various aspects of CMP, followed by 13.33 and 15.00 per cents of them having low and high level of adoption, respectively. It was also found that they adopted recommended practices of ‘Transportation’ up to maximum extent with Adoption Index (AI) of 86.50, followed by ‘Feeding’ (AI=68.68), however, extent of adoption regarding ‘Cleaning of utensil’ (AI=43.40) and ‘Healthy herd management’ (AI=45.23) was found less.

Relative contributions of neighbourhood and animal movements to Coxiella burnetii infection in dairy cattle herds.

Q fever in dairy cattle herds occurs mainly after inhalation of contaminated aerosols generated from excreta by shedder animals. Propagation of Coxiella burnetii, the cause of the disease between ruminant herds could result from transmission between neighbouring herds and/or the introduction of infected shedder animals in healthy herds. The objective of this study were (i) to describe the spatial distribution C. burnetii-infected dairy cattle herds in two different regions: the Finistère District in France (2,829 herds) and the island of Gotland in Sweden (119 herds) and (ii) to quantify and compare the relative contributions of C. burnetii transmission related to neighbourhood and to animal movements on the risk for a herd to be infected. An enzyme--linked immunosorbent assay was used for testing bulk tank milk in May 2012 and June 2011, respectively. Only one geographical cluster of positive herds was identified in north-western Finistère. Logistic regression was used to assess the association of risk for a herd to test positively with local cattle density (the total number of cattle located in a 5 km radius circle) and the in-degree (ID) parameter, a measure of the number of herds from which each herd had received animals directly within the last 2 years. The risk for a herd to test positively was higher for herds with a higher local cattle density [odds ratio (OR) = 2.3, 95% confidence interval (CI) = 1.6-3.2, for herds with a local density between 100 and 120 compared to herds with a local density 60]. The risk was also higher for herds with higher IDs (OR = 2.3, 95% CI = 1.6-3.2, for herds with ID 3 compared to herds that did not introduce animals). The proportion of cases attributable to infections in the neighbourhood in high-density areas was twice the proportion attributable to animal movements, suggesting that wind plays a main role in the transmission.