Seroepidemiology of trichinellosis in Florida swine

Surveys for swine trichinellosis, conducted in Florida using a commercial enzyme-linked immunosorbent assay (ELISA) kit with a modified protocol for screening and Western blot as a definitive test, revealed significantly different seroprevalences of 0.3% (four of 1294 samples) and 2.8% (five of 179 samples) in domestic breeding swine and feral swine, respectively.

Seropositive swine were identified in four of 114 (3.5%) domestic swine herds and in three of six feral swine regions. The location of two domestic herds with seropositive swine within approximately 2 miles of one another, and adjacent to a region where a seropositive feral hog was identified, suggests that a focus of trichinellosis exists in this area. The occurrence of singleton reactors in domestic herds may be explained by the absence of the common modes of transmission and suggests that swine were infected incidentally by feeding on the infected carcasses of small wild mammals or rodents. Although the presence of Trichinella spiralis spiralis isolates cannot be excluded, it is more likely that a sylvatic Trichinella isolate occurs in Florida swine. This conclusion is supported by the low seroprevalence in domestic swine, the failure to detect larvae in domestic or feral swine and the high prevalence in Florida panthers.     

Status of Trichinella spiralis in domestic swine and wild boar in Canada.

Evidence of the status of trichinellosis in Canada's national swine herd is provided from data acquired through national surveillance programs and from a prevalence study of Trichinella in wild boar and domestic swine. More than 500,000 swine tested at abattoirs in ongoing animal health surveys since 1980 and 2 national swine serological surveys (1985 and 1990) showed no evidence of Trichinella infection, except for 3 occurrences in a small infected zone in Nova Scotia. The prevalence study of domestic swine and wild boar was conducted for the prevalence of Trichinella after an epidemiological investigation of a 1993 outbreak of human trichinellosis in Ontario showed that the disease was linked to the consumption of wild boar meat originating from 2 farms in the province. Sera and tissues were collected from 391 wild boar and 216 domestic swine originating from 228 farms in Quebec, Ontario, Manitoba and Saskatchewan. The survey examined approximately 37% of the wild boar slaughtered in Canada in 1994. A pepsin-HCl digestion test of the tissues and an ELISA performed on the sera did not yield any positive results. These findings and the lack of human cases of Trichinella from the consumption of Canadian pork for nearly 2 decades suggest that the parasite has been rare in domestic swine and wild boar raised in Canada. Trichinella spiralis has only been found sporadically in swine in a small region within Nova Scotia.     

Trichinella prevalence in swine in an endemic district in Serbia: Epidemiology and control

Endemic trichinellosis is re-emerging in Serbia and it is a serious problem both from the perspective of human health and animal husbandry. The widespread appearance of human trichinellosis is attributed to a high prevalence of Trichinella infection in domestic animals, especially swine. Epidemiological data presented in this paper were collected during a 12-year period (1995–2006) at small private swine farms in the region of Branicevo, Serbia where a high Trichinella prevalence in slaughter pigs (0.57%) has been detected. To further monitor Trichinella prevalence in swine, a serological survey, using ELISA, was performed in 2006. Of 916 swine tested by ELISA, Trichinella specific antibodies were detected in 15 (1.64%), while suspect results were obtained in 10 (1.09%). Positive or suspect animals originated from all parishes except one (Pozarevac). Our results point to the need for systematic monitoring in pigs to achieve a better control of trichinellosis in Serbia.     

Evaluation of excretory-secretory antigens for the serodiagnosis of swine trichinellosis

Groups of hog sera from endemic and non-endemic areas for swine trichinellosis in Yugoslavia were tested by ELISA using excretory-secretory (ES) antigens collected from T. spiralis muscle larvae maintained in vitro for 24, 48 or 72 h. The 24-h ES had the highest level of specificity for T. spiralis infection. Antigen preparations recovered after 48 or 72 h yielded an increasing rate of false-positive reactions. Additional antigens occurred in the 48- and 72-h ES preparations as determined by gel electrophoresis and monoclonal antibody binding. The occurrence of false-negative reactions was directly correlated with T. spiralis worm burdens. Hogs with muscle larvae densities greater than 10 larvae per gram were all positive by ELISA. Among 17 hogs with less than 10 larvae per gram, only one hog was negative by ELISA with 24-h ES antigen; the false-negative rate was higher with 48- and 72-h ES. These results show that ES antigen produced during the first 24 h of in vitro cultivation is highly specific for the immunodiagnosis of swine trichinellosis.     

Comparison of monoclonal antibody-based competitive and indirect enzyme-linked immunosorbent assays for the diagnosis of swine trichinosis

A competitive enzyme-linked immunosorbent assay (ELISA) for the detection of swine trichinosis has been developed using a biotinylated monoclonal antibody and an avidin-enzyme conjugate. The assay is based on competitive binding between swine serum antibodies and a monoclonal antibody specific for an antigenic determinant present on proteins from Trichinella spiralis excretory-secretory products with molecular weights of 45,000, 49,000, and 53,000. The competitive ELISA reliably detected pigs infected experimentally with T. spiralis and eliminated false-positive reactions in pigs infected with other swine nematodes, particularly Trichurus suis. When the competitive ELISA and an indirect ELISA using affinity-isolated antigen were compared using serum from pigs with naturally-acquired infections of T. spiralis, both tests were highly effective in detecting infected animals.     

Re-emergence of trichinellosis in southeastern Europe due to political and economic changes

The countries of southeastern Europe including the Balkan region and bordering countries - Albania, Bulgaria, Bosnia and Herzegovina, Croatia, Greece, Hungary, Macedonia, Romania, Serbia and Montenegro, Slovenia, and the European part of Turkey - occupy a very important strategic position and represent a land bridge between Europe and Asia. In the majority of southeastern European countries, cases of trichinellosis among the human and animal populations were described in the late 19th or early 20th centuries. Trichinella infections among wildlife were also described in the aforementioned countries. Today, the prevalence of trichinellosis is different between the Balkans and bordering countries. A high prevalence of trichinellosis in domestic animals and humans has been reported in Bulgaria, Serbia and Montenegro, Romania and Croatia. A moderate prevalence was found in Bosnia and Herzegovina. In Hungary, human trichinellosis has not been present for a long period of time. However, sporadic cases were recorded in swine over the last 2 years. Trichinellosis has not been found among domestic animals and humans in Greece and Macedonia in recent years while in Turkey and Slovenia human trichinellosis is sporadic. The re-emergence of trichinellosis is connected with the changes in the social and political systems in Bulgaria and Romania. In Serbia and Montenegro as well in Croatia, however, a re-emergence of trichinellosis was due not only to political and social changes but also to wars that took place in these countries during the last years of the 20th century. Social, economic and political factors responsible for the re-emergence of trichinellosis in southeast European countries are discussed in this communication.     

Enzyme-linked immunosorbent assay for detecting antibodies in swine infected with Mycobacterium avium

Enzyme-linked immunosorbent assay (ELISA) was used for detecting the antibodies in sera from swine experimentally infected with Mycobacterium avium. Positive ELISA reactions were observed in the sera of each of six swine at postinoculation weeks 2, 4, 6, 8, and 10; no reaction was observed in noninoculated controls. The ELISA reactions were observed in each of two swine at 4, 6, 8, 10 weeks following exposure to M avium-infected swine. Mycobacterium avium-purified protein derivative and killed cells of M avium serotype 4/8 and serotype 8 provided suitable ELISA reactions in M avium-infected swine.     

Enzyme-linked immunoassay in the diagnosis of leptospirosis in domestic animals using peroxidase-conjugated protein-A

The ELISA test for detection of antibodies to Leptospirosis in domestic animals was performed using Staphylococcal protein-A coupled to peroxidase in place of antisera to IgG. Genus- and type-specific antigens were extracted with SDS technique from four pathogenic serotypes and two non-pathogenic ones, and they were identified with the aid of ELISA using specific rabbit antisera. Micro-agglutination (MA) and ELISA were compared using a total of 48 positive swine sera and a 100% agreement was obtained, since with sera from 16 dogs clinically suspected of Leptospirosis the ELISA resulted highly more sensitive and precocious than MA in detecting specific antibodies.     

Evaluation of an enzyme-linked immunosorbent assay for detection of Eperythrozoon suis antibodies in swine.

An ELISA was developed and tested to detect antibodies to Eperythrozoon suis in swine. Results were compared with those of the indirect hemagglutination (IHA) test. Antigen isolated from swine heavily infected with E suis was used for both tests. Comparison of the ELISA with the IHA test revealed a significant (P less than 0.001) correlation between results. Of 114 samples obtained from 9 swine infected with E suis, 87.7% were seropositive (titer greater than or equal to 200) via the ELISA, and 80.7% were seropositive (titer greater than or equal to 20) via the IHA test. The sensitivity of the ELISA was greater than that of the IHA test. All blood samples obtained from specific-pathogen-free swine tested negative for E suis antibody. Cross-reactions were not observed between E suis antigen and antisera against various swine and cattle disease agents using ELISA. We concluded that the ELISA may be used for rapid and effective diagnosis of infection with E suis in swine.     

Pandemic A/H1N1/2009 influenza virus in swine, Cameroon, 2010

Although swine origin A/H1N1/2009 influenza virus (hereafter "pH1N1″) has been detected in swine in 20 countries, there has been no published surveillance of the virus in African livestock. The objective of this study was to assess the circulation of influenza A viruses, including pH1N1 in swine in Cameroon, Central Africa. We collected 108 nasal swabs and 98 sera samples from domestic pigs randomly sampled at 11 herds in villages and farms in Cameroon. pH1N1 was isolated from two swine sampled in northern Cameroon in January 2010. Sera from 28% of these herds were positive for influenza A by competitive ELISA and 92.6% of these swine showed cross reactivity with pandemic A/H1N1/2009 influenza virus isolated from humans. These results provide the first evidence of this virus in the animal population in Africa. In light of the significant role of swine in the ecology of influenza viruses, our results call for greater monitoring and study in Central Africa.     

Comparison of three serotests for the detection of pseudorabies antibodies in pigs

The serum-neutralization test (SN), enzyme-linked immunosorbent assay (ELISA) and the radial immunodiffusion enzyme assay (RIDEA) were compared for the detection of pseudorabies (PRV) antibodies in swine sera. A total of 1285 serum samples were tested. All three tests were considered useful in determining the PRV antibody status of swine on a herd basis, but available evidence supports the continued use of SN as the definitive test because of possible false positive reactions associated with ELISA and RIDEA.     

Wild boars (Sus scrofa) as reservoirs of Brucella suis biovar 2 in Croatia

This work presents the results of findings for brucellosis in wild boars and domestic swine in two regions of Croatia. In the region of Djakovo the blood samples of 211 wild boars were analysed and in 29.4% of the samples serologically positive reactions were established. In the same region the blood samples of 1080 domestic swine on pastures were also analysed and positive serological reactions were established in 12.3%. In the regions around Lonjsko Polje the blood samples of 53 wild boars were analysed and in 22.6% of them positive serological reactions were established. On several locations around Lonjsko Polje the blood samples of 901 domestic swine were serologically analysed and 13.5% of the swine were found to be seropositive. Bacteriological analyses of submitted materials from 24 wild boars resulted in isolation of Brucella from seven (29.2%) samples, and from 43 samples originating from domestic swine that had aborted and had been serologically positive, Brucella were isolated from 25 (58.1%) swine, as well as from 10 (62.5%) out of 16 aborted piglets. In all the isolates Brucella suis biovar 2 was identified. Wild boars are carriers and reservoirs of Brucella suis biovar 2 in Croatia.     

An epidemiological overview of swine trichinellosis in China

Trichinellosis is a major food-borne zoonosis with health, social, and economic impacts. Epidemiological data on swine trichinellosis in China from 2005 to 2009 were obtained from seven Provinces/autonomous regions/Municipalities (P/A/M) and analyzed and sero-epidemiological data were acquired from five P/A. The seroprevalence ranged from 0.01% to 29.95% as determined by enzyme-linked immunosorbent assay or an immunochromatographic strip method. The prevalence of Trichinella infection in swine slaughtered at abattoirs varied from 0% to 5.75% in five P/A. Between 2005 and 2009, endemic areas of swine trichinellosis were located mainly in the Western (Guangxi and Qinghai), central (Henan and Hubei), and North-eastern parts (Heilongjiang) of China.Swine trichinellosis in China is transmitted mostly through garbage. Pigs infected with Trichinella are predominately from small backyard farms where animals are raised under poor hygienic conditions, and from rural and mountainous areas where they range freely at pasture. The prevalence of Trichinella in pork sold at the market was reported in four P/A, and varied from 0.06% to 5.6% as determined by trichinoscopy or the digestion method. From 2005 to 2009, 15 outbreaks of human trichinellosis, with 1387 cases and 4 deaths, were recorded in three P/A of South-western China. Twelve (85.71%) of these 15 outbreaks were caused by the eating of raw or undercooked pork, which remains the predominant source of trichinellosis in humans. Pig-rearing practices must be improved, and mandatory inspection of pork further strengthened in rural and mountainous areas in Western China for the control of the disease.     

Comparison of three methods for detection of prolonged experimental trichinellosis in pigs

Three methods were employed for the diagnosis of porcine trichinellosis. The pooled sample digestion method and trichinoscopy served as European Community (EC) reference techniques, whereas the reliability of the Enzyme Linked Immunosorbent Assay (ELISA) was tested by 11 laboratories of the European Community and Sweden. Three groups of 6 piglets each were orally inoculated with 50, 150 and 1500 Trichinella spiralis larvae into each animal. Another group of 6 animals served as a non-infected control. Animals were slaughtered and serum and muscle samples were collected at Weeks 4, 12 and 40. The material was mailed under code and examined in all participating laboratories. ELISA proved to be a sensitive technique. ELISA micro assay was the most sensitive procedure. Of the direct techniques the reference pooled sample digestion method was more sensitive than trichinoscopy. It was concluded that both micro and macro ELISA can be used with confidence for the detection of low grade, longstanding experimental T. spiralis infections in swine.     

An enzyme-linked immunosorbent assay (ELISA) for the detection of anti-chlamydial antibodies in pig sera

The evaluation of an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against chlamydiae in pig sera is described. The most widely used serological test is the complement fixation test (CFT). The CFT has a lack of sensitivity and specificity because of low antibody titers and unspecific reactions. Eight conventionally raised pigs were exposed to a pathogenic strain of Chlamydia suis, four controls were mock infected. The immune responses was monitored by CFT and indirect ELISA. There was no agreement between CFT and ELISA data. These results were confirmed by a study with 191 sera from nine pig farms. As shown by ELISA and PCR chlamydiae are widespread in swine.     

Husbandry, parasitic and other diseases as factors in the reliability of the enzyme linked immunosorbent assay (ELISA) for detection of trichinellosis in pigs

Serum samples were obtained from pigs originating from specified pathogen-free farms, large industrialised farms and small conventional farms. All animals proved to be free of Trichinella spiralis by a pooled sample digestion method. Careful meat inspection studies on parasitic infections other than trichinellosis, and other inflammatory reactions were recorded and used for subdivision of the animals in different groups. It was concluded that animal husbandry, parasitic infections, or inflammatory reactions have not influenced the mean extinction values of an ELISA for the detection of T. spiralis antibodies, however, the specified pathogen free animals yielded somewhat lower results.     

A sensitive dot immunobinding assay for serodiagnosis of African swine fever virus with application in field conditions.

The present work describes a simple dot immunobinding assay (DIA) for African swine fever virus (ASFV) antibody detection that can be used under field conditions. The assay uses nitrocellulose strips dotted with a cytoplasmic soluble antigen (CS-P) of ASFV. The nitrocellulose strips are adhered to a plastic handle. The test serum samples react with the CS-P, and antibodies are detected using a protein A-peroxidase conjugate. Both incubations are carried out at 20 C. The efficacy of the DIA as a screening test for ASFV was compared to an enzyme-linked immunosorbent assay (ELISA) and an immunoblotting (IB) test using 343 sera collected from natural African swine fever epizootics and from inapparent ASFV carriers. The DIA had comparable sensitivity to both reference techniques, and all samples positive in the ELISA and IB test were also positive in the DIA. False-positive reactions were not detected when whole blood or poorly preserved serum samples were tested by DIA. Some poorly preserved sera that were positive initially by the ELISA were no longer ELISA positive in a later run, although they were positive in IB and DIA. These positive DIA and IB test results could be caused by the differences in antibody epitope binding.     

猪金属硫蛋白抗体的制备及应用

以自猪肝提取的Zn—MT与BSA的偶联物为抗原，免疫昆明小鼠制备了多克隆抗体。获得的抗体经鉴定后用于建立检测猪MT的间接竞争EI。ISA。结果表明：制备的IgG达到电泳纯，是猪MT的特异性抗体。所建立的间接竞争ELISA的灵敏度为4．1ng／mL，批内变异系数是9．976％，批间变异系数为14．3858％，可用于猪体MT的定性、定量测定。     

Development of real-time polymerase chain reaction assays for rapid detection and differentiation of wild-type pseudorabies and gene-deleted vaccine viruses

The successful eradication of pseudorabies in U.S. domestic swine was accomplished through the use of glycoprotein E (gE) deleted modified live virus vaccines and an accompanying gE differential enzyme-linked immunosorbent assay (ELISA). Yet, pseudorabies virus (PRV) was established in feral swine in the United States, becoming a potential reservoir of PRV for infection of domestic swine and other native wildlife. A critical need for the current PRV surveillance program in the United States is the rapid detection of PRV infection. For this reason, a set of 2 real-time polymerase chain reaction (PCR) assays by using TaqMan chemistry was developed and evaluated for their capability in the detection and differentiation of field and vaccine strains of PRV. PCR primers and probes were designed for gB and gE genes of PRV, respectively. The newly developed PRV-specific real-time PCR assays could detect all wild-type PRV isolates from diagnostic submissions and differentiate them from vaccine strains. The analytical sensitivity of the assays was approximately 0.1 plaque-forming units per reaction. The assays were highly specific for PRV, because no positive results were obtained from testing other common swine viral pathogens and other animal herpesviruses. The results of testing samples from domestic and feral swine and from bovine showed that the real-time PCR assays are more sensitive than gel-based PCR. These results demonstrated the potential application of the developed real-time PCR assays as a differential test for rapid and specific detection of PRV in domestic and feral swine, as well as nonporcine species that can be infected with PRV and serve as carriers.     

Technical note: Development of an enzyme-linked immunosorbent assay for the determination of florfenicol and thiamphenicol in swine feed

One polyclonal antibody against florfenicol and thiamphenicol was produced and a competitive ELISA was developed for the detection of florfenicol and thiamphenicol in swine feed. The ELISA gave a 50% inhibiting concentration of 1.02 ng/mL for florfenicol. For swine feed fortified with 0.05 to 3.0 mg/kg, the interassay recoveries of florfenicol and thiamphenicol ranged from 86.4 to 118.6%, whereas intraassay recoveries of both drug ranged from 90.1 to 126.5% with less than 15% CV. Results obtained from HPLC-tandem mass spectrometry indicated this ELISA procedure could be used as a convenient method for rapid screening of florfenicol and thiamphenicol in swine feed.