Urinary PCR as an increasingly useful tool for an accurate diagnosis of leptospirosis in livestock

The aim of the present study was to consider the wide usage of urinary PCR as an increasingly useful tool for an accurate diagnosis of leptospirosis in livestock. A total of 512 adult animals (300 cattle, 138 horses, 59 goats and 15 pigs), from herds/flocks with reproductive problems in Rio de Janeiro, Brazil was studied by serology and urinary PCR. From the 512 serum samples tested, 223 (43.5 %) were seroreactive (cattle: 45.6 %, horses: 41.3 %, goats: 34%and pigs: 60 %). PCR detected leptospiral DNA in 32.4 % (cattle: 21.6 %, horses: 36.2 %, goats: 77.4 % and pigs: 33.3 %. To our knowledge there is no another study including such a large number of samples (512) from different species, providing a comprehensive analysis of the usage of PCR for detecting leptospiral carriers in livestock. Serological and molecular results were discrepant, regardless the titre, what was an expected outcome. Nevertheless, it is impossible to establish agreement between these tests, since the two methodologies are conducted on different samples (MAT - serum; PCR - urine). Additionally, the MAT is an indirect method and PCR is a direct one. In conclusion, we have demonstrated that urinary PCR should be considered and encouraged as an increasingly useful tool for an accurate diagnosis of leptospirosis in livestock.     

Diagnostic performance of PCR and ELISA on blood and milk samples and serological survey for small ruminant lentiviruses in central Spain

The diagnostic performance of an ELISA for the detection of antibodies to the small ruminant lentiviruses (SRLVs) maedi-visna virus and caprine arthritis-encephalitis virus in milk and corresponding blood samples was evaluated in 50 sheep. The agreement between ELISA results in blood and milk was 90 per cent, and the κ value was 0.79. In addition, a serological survey in the central zone of Spain was performed using milk samples from 413 animals (250 sheep and 163 goats) from 12 flocks/herds. All flocks/herds had some animals that were positive for SRLV. Among the animals, 60.0 per cent of the sheep and 8.0 per cent of the goats tested were seropositive. Each sample was also tested using a PCR technique, which increased the percentage of positive animals detected. Using a combination of ELISA and PCR gave a total of 72.2 per cent of sheep and 28.8 per cent of goats positive for SRLV.     

Leptospirosis in sheep and goats under tropical conditions

Inadequate management practices and poor reproductive performance have been reported as fundamental factors on reducing the levels of productivity in livestock. Different pathogens have been reported in small ruminants' herds/flocks with reproductive failures. The aim of the present study was to review aspects of leptospirosis in small ruminants, mainly its impact on reproduction and consequently on productivity of the herds/flocks under tropical conditions. Leptospiral infection in goats and sheep is common in several countries, and those species can also act as carriers of leptospires. Severe disease is often associated to young animals and is frequently associated to incidental serovars. In contrast, subclinical infection is mainly characterized by reproductive problems, such as infertility, abortion, occurrence of stillbirths, and weak lambs/goat kids. Moreover, laboratorial tests are essential to achieve an accurate diagnosis of the infection. Microscopic agglutination test is the most common indirect test of leptospirosis, being used worldwide. In small ruminants, PCR consists on a recommendable method for diagnosing animals that carry leptospires. Control of leptospirosis in small ruminants involves measures such as the identification and treatment of the carriers and other sources of infection, quarantine in acquired animals, and systematic immunization with commercial vaccines containing the circulating serovars in the herd/flock. Productivity of small ruminant breeding can dramatically increase with adequate sanitary conditions and control of leptospirosis. Immunization of all the animals combined to the treatment of carriers may successfully control the infection and importantly reduce the economic reproductive hazards that are observed under tropical conditions.     

Incidence of abortions caused by leptospirosis in sheep and goats in Spain

From 1970 to 1985, 973 outbreaks of abortion in sheep and 262 outbreaks of abortion in goats from southern Spain were studied. Of these, 1.7 and 2.6% respectively were caused by leptospiras, chiefly by the serovar pomona (11 flocks of sheep, 64.7%, and six herds of goats, 75.0%) and in a lower proportion the serovars sejroe (three flocks of sheep 17.6%, and one herd of goats, 12.5%), icterohaemorrhagiae (two and one outbreaks respectively) and grippotyphosa in one ovine flock (5.8%). The mean rates of attach (X + SD) of abortions by leptospirosis have been estimated as 16.9 + 6.5% in ovine outbreaks and 20.7 + 8.3% among goats.     

Seroprevalence and risk factors for leptospirosis in cattle,sheep, and goats at consorted rearing from the State of Piauí, northeastern Brazil

Leptospirosis is an endemic disease in Latin America, caused by pathogenic bacteria of the genus Leptospira. It is considered one of the main causes responsible for the negative economic impact on global livestock by causing reproductive problems. The research aimed to determine the prevalence of leptospirosis in cattle, sheep, and goats at consorted rearing in the micro-region of Teresina, Piauí state, northeastern Brazil, as well as to identify prevalent serovars and risk factors associated with seroprevalence. Serum samples were analyzed in 336 sheep, 292 goats, and 253 cattle using microscopic agglutination test (MAT). Overall, 378 samples were positive to MAT, with seroprevalence of 42.9%. The prevalences in cattle, sheep, and goats were 50.5, 40.5, and 34.6%, respectively. All herds presented at least one seropositive animal; the Hardjo/Wolffi serovar association was the most common in cattle and Icterohaemorrhagiae in goats and sheep. Beef production (OR?=?4.9), cattle herd over 35 animals (OR?=?4.0), feeding on pasture (OR?=?6.4), weir and/or stream as water source (OR?=?2.1), and no veterinary services (OR?=?2.9) were risk factors for cattle infection. For sheep, intensive management system (OR?=?5.3), suspended slatted facilities (OR?=?2.2), more than 20 sheep in reproductive age (OR?=?1.9), and absence of deworming (OR?=?3.5) were the risk factors, while for goats, the identified risk factors were sheep herd over 52 animals (OR?=?1.9) and no veterinary services (OR?=?1.8). We conclude that the infection was spreading in consorted herds in this region. Thus, it would be interesting and important to conduct educative activities to farmers on the economic impacts of this disease and the need of preventive and control strategies mainly focused on sanitary measures and animal handling.     

Risk factors to incidental leptospirosis and its role on the reproduction of ewes and goats of Espírito Santo state,Brazil

Ovine and caprine stockbreeding have been gaining attention in developing countries as an attractive investment. On these animals, infectious diseases of the reproductive tract, such as leptospirosis, can compromise the production leading to economic losses. The present study aimed to determine the risk factors associated with incidental leptospirosis and its influence on the reproductive parameters of ewes and goats of Espírito Santo state, Brazil. A total of 737 animals distributed on 24 herds/flocks were studied, and an overall prevalence of 10.9 % seroreactive animals was observed. Serogroup Icterohaemorrhagiae was the most frequent in goats (97.0 %) as well as in ewes (78.3 %). Regarding risk factors related to leptospirosis, the presence of waterholes and the semi-intensive breeding system were the most important associated to seroreactivity. Besides, there was an observed association between seroreactivity and reproductive failures (P?<?0.05). Moreover, seroreactive ewes (relative risk (RR)?=?1.3) and goats (RR?=?1.9) presented more chances to have abortions than seronegative animals. Furthermore, seroreactive ewes presented 11.6 more chances of having premature births when compared to the seronegative ones. It can be concluded that Leptospira infection, mainly those caused incidental strains (such as Icterohaemorrhagiae serogroup), is a significant factor to reduce the productivity of small ruminants’ herds/flocks in the studied region, and environmental measures must be considered on control programs.

     

High seroprevalence of caseous lymphadenitis in Brazilian goat herds revealed by Corynebacterium pseudotuberculosis secreted proteins-based ELISA

We conducted a seroepidemiological survey to determine the prevalence of caseous lymphadenitis (CLA) in goat herds in Minas Gerais state, Brazil. Serum samples were collected from goats (n = 676) from 108 rural properties in 2001, covering most of the sub-regions of this ca. 586,500 square kilometer state. Antibodies against Corynebacterium pseudotuberculosis secreted proteins were detected by an indirect enzyme-linked immunosorbent assay (ELISA). Most of the animals (78.9%) tested positive for CLA; 98% of flocks presented at least one seropositive animal. Goats managed under an extensive production system had a significantly higher seroprevalence of CLA than those in intensive and semi-intensive operations. The age distribution of the animals in the flocks affected the prevalence of this disease; however, goat breed did not. We found seropositivity against C. pseudotuberculosis to be highly prevalent in these Brazilian goat herds; consequently, appropriate management practices for the control of CLA should be implemented.     

Determination of prevalence and risk factors of infection with Babesia in small ruminants from Greece by polymerase chain reaction amplification

A total of 124 blood samples were collected from 92 sheep and 32 goats from 21 randomly selected herds located in two regions of Greece. Data on the characteristics of the animals (species, gender, age, tick burden, presence of haemoglobinuria, prior treatment for babesiosis) and the herd (location, size, species of animals, dogs associated with the herds, tick burden of dogs associated with the herds) were collected through questionnaires. Nineteen animals (15%) produced the DNA fragment specific for Babesia of which 16 were sheep and three were goats. Nucleotide sequence of PCR products revealed 100% homology with Babesia ovis 18S rRNA gene. Nine farms (43%) were found positive for B. ovis. The percentage of positive animals in each farm varied between 10 and 61%. The relative risk of the presence of ticks in sheep and goats (p<0.01) and farm dogs (p<0.01) for PCR-positive results for B. ovis in sheep and goats was found 6.63 and 4.14, respectively.     

Shedding and Seroprevalence of Pathogenic Leptospira spp. in Sheep and Cattle at a New Zealand Abattoir

A cross‐sectional study was carried out on sheep and cattle slaughtered at a New Zealand abattoir from September to November 2010 to investigate the supplier‐specific shedding rate, renal carriage rate and seroprevalence of leptospires. In the 2008/2009 season, this abattoir experienced three human leptospirosis cases from 20 staff, of which two were hospitalized. Urine, kidney and blood samples were collected from carcasses of 399 sheep (six suppliers, 17 slaughter lines) and 146 cattle (three suppliers, 22 slaughter lines). The urine and kidney samples were tested by quantitative real‐time PCR (qPCR), while serum samples (from coagulated blood samples) were tested by microscopic agglutination test (MAT). In total, 27% (73/274; 95% CI: 18–37) of urine samples tested positive by qPCR. Species‐specific shedding rates (prevalence of positive urine qPCR) were 31% (95% CI: 17–48) for sheep and 21% (95% CI: 14–30) for cattle. For 545 kidney samples tested, 145 were qPCR positive (27%; 95% CI: 17–39). The average prevalence of kidney qPCR positivity was 29% (95% CI: 17–45) for sheep and 21% (95% CI: 15–28) for cattle. Three hundred and thirty of 542 sampled sheep and cattle had antibodies against Leptospira borgpetersenii serovar Hardjobovis (Hardjobovis) and/or Leptospira interrogans serovar Pomona (Pomona), based on reciprocal MAT titre ≥1 : 48 (overall seroprevalence of 61%; 95% CI: 48–73). Seroprevalence was 57% (95% CI: 40–72) for sheep and 73% (95% CI: 59–83) for cattle. Among the seropositive animals, 41% (70/170; 95% CI: 30–54) were shedding (tested positive by urine qPCR) and 42% (137/330; 95% CI: 30–54) had renal carriage (tested positive by kidney qPCR). Some risk management options for abattoirs or farms to prevent human leptospirosis infections include vaccination of maintenance hosts, the use of personal protective equipment, and the application of urine qPCR to detect shedding status of stock as surveillance and as an alert.     

Leptospirosis as the most frequent infectious disease impairing productivity in small ruminants in Rio de Janeiro,Brazil

Despite the importance of small ruminants breeding in developing countries, milk/meat productivity remains unsatisfactory. Infectious diseases, such as leptospirosis, brucellosis, and small ruminant lentiviruses (SRLVs), contribute to this scenario. The objective of the present study was to determine the role of each of these diseases in the productivity of small ruminants breeding in Rio de Janeiro, Brazil. In goats, 343 samples were tested for leptospirosis, 560 for Brucella abortus, and 506 for caprine arthritis-encephalitis (CAE), whereas in sheep, 308 samples were tested for leptospirosis, 319 for B. abortus, 374 for Brucella ovis, and 278 for Maedi-Visna (MV). Regarding leptospirosis, 25.9% of goats and 47.4% sheep were seroreactive, with serovar Hardjo the most prevalent in both species. Anti-B. abortus agglutinins were found in 0.7% of all samples, exclusively in goats. In relation to SRLVs, 8.6% of goats and 3.2% of sheep samples were positive for CAE and MV, respectively. Leptospirosis was the major infectious problem in the small ruminants sampled and may contribute to impaired productivity of these animals.     

PCR detection of lentiviral GAG segment DNA in the white blood cells of sheep and goats

A PCR assay for the detection of small ruminant lentiviral gag DNA (provirus) in the white blood cells of sheep and goats was developed and compared with a serological test (AGIDT). A sample of the DNA prepared from the white blood cells in 3 ml of blood from 208 sheep and goats from 18 different flocks was subjected to PCR assay. One of 85 animals from flocks accredited under the Dutch national MVV/CAEV control programme was positive by PCR while none was positive by AGIDT. In infected flocks, the AGIDT appeared slightly more sensitive, but preliminary results show that the sensitivity of the PCR assay may be further improved by increasing the number of monocytes tested. The PCR assay, however, was clearly more sensitive in detecting animals in the early stages of infection. With the use of a set of mixed primers and probes, the assay was able to detect the variety of CAEV and MVV strains occurring in the field.     

Epizootiologic study of bluetongue: virologic and serologic results

Heparinized blood and serum samples were obtained from 1,295 ruminants in herds or flocks with bluetongue virus (BTV) infection in 4 western states. Submissions were from herds or flocks with clinical bluetongue (BT), as well as from animals on premises with no history of BT disease. Insects, including Culicoides variipennis, were collected in areas enzootic for BT disease. Viral isolations were in 10-day-old embryonating chicken eggs that were then adapted to Vero cells for serotyping. Sera were tested from group-specific antibody to BTV by the micro agar gel precipitin (AGP) test. Viral isolations were from cattle (81), sheep (122), goats (9), antelope (2), and C varipennis (5). There were 7 isolates of serotype 120, 114 of serotype 11, 42 of serotype 13, and 56 of serotype 17. In herds or flocks from which BTV was isolated, 51% of cattle, 56% of sheep, 21% of goats, and 52% of antelope had AGP antibodies. Virus was isolated from 43% of the cattle and 23% of the sheep that had no demonstrable evidence of AGP antibodies. Viral isolations were seasonal, occurring from August until December. Approximately 30% of the herds or flocks from which virus was isolated had more than one serotype of virus causing infection.     

Ovine and caprine toxoplasmosis (Toxoplasma gondii) in aborted animals in Jordanian goat and sheep flocks

Two hundred and fifty-five biological samples (106 aborted foetal tissue samples and 149 blood samples from aborted sheep and goats) were collected from 188 animals during the lambing season from September 2009 to April 2010 from the Mafraq region of Jordan. The sampled animals belonged to 93 goat and sheep flocks that had cases of abortion. A total of 169 (66.3%) biological samples were collected from sheep and 86 (33.7%) from goats. Seventy-six (29.8%) biological samples (45 blood and 31 tissue samples) were positive for Toxoplasma gondii by PCR assay. The positive samples were obtained from 43 sheep and 23 goats. The overall toxoplasma-specific prevalence rate was 35.1% (66/188). Forty flocks (43%) had at least one T. gondii PCR-positive animal. The risk factors related to flock health status and farm management that are hypothesized to be associated with T. gondii PCR positivity were also assessed using multiple logistic regressions. The presence of cats (OR = 4.74), a large flock size (OR = 2.76) and the method of disposing the aborted foetuses (OR = 3.77) were all statistically significant (P < 0.05) risk factors that were positively associated with toxoplasma positivity in goat and sheep flocks.     

Impact of natural sheep-goat transmission on detection and control of small ruminant lentivirus group C infections

Dissemination of small ruminant lentivirus (SRLV) infections in Norway is affected by the different control strategies used for maedi-visna virus (MVV) infections in sheep and caprine arthritis-encephalitis virus (CAEV) infections in goats. Here we investigated SRLV phylogenetic group variants in sheep. CAEV-like isolates, belonging to phylogenetic group C, were found among both seropositive sheep and goats in mixed flocks, in which sheep and goats are kept together. Intra-herd clustering confirmed that mixed flock animals were infected by the same virus variant, suggesting ongoing interspecies transmission. Few sheep flocks were found to be infected with the MVV-like phylogenetic group A. The apparent absence of SRLV group A type in goats is probably due to the MVV control programme and animal management practices. SRLV group C targets lungs and mammary glands in sheep, and induces typical SRLV pathological lesions. SRLV group C isolated from the sheep mammary glands suggested a productive infection and potential for transmission to offspring. SRLV group C was most prevalent among goats. A lower PCR sensitivity in seropositive sheep suggested a lower load of SRLV group C provirus in sheep than in goats. Higher genetic divergence of group C than in other SRLV groups and extensive heterogeneity among group C isolates in the matrix C-terminal region demonstrate the need for identifying conserved target regions when developing PCR protocols for SRLV detection. As sheep and goats may serve as reservoirs for all SRLV genogroup types, successful control programmes require inclusion of both species.     

Epidemiology behavior of leptospirosis in Ciénaga de Oro,Córdoba (Colombia)

The purpose of this study was to determine the epidemiology of leptospirosis in rural areas of Ciénaga de Oro, Córdoba, Colombia, a convenience sampling was carried out on 13 farms. The sample size was 325 reproductive age cows, 11 canine samples, and 20 humans. The samples were subjected to MAT analysis with 11 serogroups of Leptospira interrogans sensu lato. Once the MAT results were received, urine samples were collected from 78 cows, along with 39 water samples, for bacteriological cultures and PCR for the 16S rRNA gene in L. interrogans sensu lato. Positive PCR samples were sequenced to determine the possible genome species. The leptospirosis seroprevalence was 74.5% in the cattle, 70.0% in the dogs, and 45.5% in the humans. Although isolation was not achieved, L. interrogans sensu lato was detected by PCR in three urine samples and in a sample of wastewater. The sequencing confirmed the circulation of pathogenic species. The high prevalence of antibodies for L. interrogans sensu lato and the molecular evidence led to the inference that the rural areas of Ciénaga de Oro are endemic and that cattle can act as renal carriers and contaminate water sources, which increases the risk of contracting leptospirosis.     

Changes in the risk management of Salmonella enterica subspecies diarizonae serovar 61:(k):1, 5, (7) in Swedish sheep herds and sheep meat due to the results of a prevalence study 2012

Background

The prevalence of Salmonella in food producing animals is very low in Sweden due to rigorous control programmes. However, no active surveillance is in place in sheep. The authorities decided to perform a prevalence study in sheep herds because findings at slaughter indicated that sheep associated S. diarizonae (S. enterica subspecies diarizonae serovar 61:(k):1, 5, (7)) might be common in sheep. Sampling was stratified by herd size in two groups, small herds with ≤ 30 animals and large herds with > 30 animals. In each stratum, 237 herds were selected at random. Faecal samples received from 244 out of the 474 randomly selected herds were analysed.

Results

A total of 40 of 100 (40%) of large herds and 17 of 144 (12%) of small herds were positive. The overall adjusted prevalence was 17.6% (95% CI, 12.9-22.2). Sheep associated S. diarizonae was detected in all counties (n = 21). Scientific opinions and an evaluation of on-farm control measures performed concluded that the impact of sheep associated S. diarizonae on human health is very low, and that risk management measures applied in response to findings of sheep associated S. diarizonae in sheep or sheep meat can be expected to have very little impact on reducing risks to human health. As a result, Swedish authorities decided to make an exemption for sheep associated Salmonella diarizonae in sheep and sheep meat in the current Salmonella control measures.

Conclusions

Sheep associated S. diarizonae is endemic in Swedish sheep herds. It is more common in large herds and not limited to certain parts of the country. The responsible authorities concluded that current risk management actions regarding sheep associated S. diarizonae in sheep and sheep meat are not proportional to the risk. This is the first time in the history of the Swedish Salmonella control programme that an exemption from the legislation has been made for a specific serovar. If there is any future indication of an increasing risk, due to e.g. change in the pathogenicity or development of antimicrobial resistance, the risk assessment will be re-evaluated and control measures reinforced if needed.     

Seroprevalence of Toxoplasma gondii infection in Norwegian dairy goats

Background

Toxoplasma gondii is a major problem for the sheep industry as it may cause reproduction problems. The importance of T. gondii in Norwegian goat herds is uncertain, but outbreaks of toxoplasmosis in dairy goat farms have been recorded. The aim of this study was to describe the prevalence of T. gondii infection in Norwegian dairy goats by using serology.

Findings

Goat serum originally collected as part of two nationwide surveillance and control programmes between 2002 and 2008 were examined for T. gondii antibodies by using direct agglutination test. In total, 55 of 73 herds (75%) had one or more serologically positive animals, while 377 of 2188 (17%) of the individual samples tested positive for T. gondii antibodies.

Conclusions

This is the first prevalence study of T. gondii infection in Norwegian goats. The results show that Norwegian goat herds are commonly exposed to T. gondii. Nevertheless, the majority of goat herds have a low prevalence of antibody positive animals, which make them vulnerable to infections with T. gondii during the gestation period.     

Risk factors associated with leptospirosis in dairy goats under tropical conditions in Brazil

Serum samples from 248 adult dairy goats from 13 flocks with lowered fertility farmed in the Rio de Janeiro region of Brazil were examined for Leptospira antibodies by MAT with 24 serovars, cut off 100. A questionnaire was completed for each herd. Antibodies were detected in 20.8% of these goats, mainly to serovar Hardjo. Risk factors associated with seroprevalence to leptospirosis were the frequency of professional veterinary supervision (OR = 2.35), climate (OR = 2.63) and grazing for more than 2h a day. Flock factors as size, type of milking and offering of food supplementation, as well as the location and topography, the type of animal housing or the presence of silos did not significantly affect seroprevalence. We suggest that a successful control program for goat leptospirosis should include a complete investigation of herd management practices, which could influence in the occurrence of the infection.     

First isolation of Histophilus somni from goats

Histophilus somni (former name: Haemophilus somnus) is a Gram-negative, facultative pathogen bacterium that colonises the mucous membranes of cattle and sheep, however it was also described in American bison and bighorn sheep. It can cause local or generalised diseases and asymptomatic carriers can also occur. The presence and the etiological role of this microorganism have not been confirmed in any other domesticated species yet. The purpose of this study was to prove the presence of H. somni in goats by bacterial isolation. Nasal, vaginal or praeputial swab samples were collected from 205 goats in 10 flocks. H. somni strains were isolated from 2 out of 10 flocks; in one flock 10 H. somni strains were isolated from the genital mucosa of 17 goats, while a single H. somni strain was cultured from a vagina of 26 animals in the other flock. Partial amplification and sequencing of the 16S rRNA gene of three H. somni strains verified the identification. The comparative examination of carbon source metabolism using the Biolog Microstation ID System (Biolog, Ca) showed a close relationship of the caprine strains, while they were less related to H. somni type strain CCUG-36157 of bovine origin. H. somni strains were isolated only in the oestrus season from goat flocks with sheep contact. This is the first paper on isolation of H. somni from goats.     

Prevalence of leptospirosis among animal herds of north eastern provinces of India

Serum samples from 840 animals were examined for Leptospira spp. antibodies by microscopic agglutination test (MAT) to assess the risk factors and the prevalence of leptospirosis among animal herds of Assam, Meghalaya, Mizoram the north eastern (NER) provinces. They were compared with Tamilnadu (TN) the southern province of India for the serovar and risk factor inconsistency. Serovar Ballum was reported to be prevalent (28.1 %) in Assam and Grippotyphosa (16.1 %) in Tamilnadu. The overall seropositivity observed was 36.8 %(206/560) from NER and 30.7 %(86/280) from TN. In this study, the higher seroprevalence was observed in pigs (42.6 %), cattle (39.8 %) and goats (26 %) in NER. Cattle (36.4 %) and goat (17.6 %) showed higher prevalence in TN. The presence of rodents in pig herds was found to be significant (P = 0.0088) in NER and it was for cattle in TN (P = 0.0063). We suggest that a program of rodent control should be included in the flock management practices aiming to reduce transmission of the leptospires.