Anisakis Sensitization in the Croatian fish processing workers: Behavioral instead of occupational risk factors?

We undertook the first study systematically evaluating the risk of Anisakis-sensitization in Croatian fish-processing workers and potential genetic susceptibility to anisakiasis. Anti-Anisakis IgE seroprevalence and risk factors for 600 employees of Croatian fish processing facilities and 466 blood donor controls, were assessed by indirect ELISA targeted with: recombinant Ani s 1 and Ani s 7 allergens, an Anisakis crude extract, the commercial ImmunoCAP kit, and questionnaires. Genetic susceptibility to anisakiasis was evaluated by genotypisation of human leukocytes alleles (HLA). Anti-Anisakis seropositive and a fraction of negative subjects were also assessed by ELISA and Western Blot (WB) for IgG seroprevalence to Trichinella spp. Overall, the observed anti-Anisakis seroprevalence inferred by indirect ELISA was significantly higher in fish processing workers (1.8%, 95% CI 0.9–3.3%) compared to the controls (0%, 0–0.8%). Seven out of 11 Ani s 1 and Ani s 7-positives and none of selected 65 negative sera, tested positive on whole-Anisakis extract (ImmunoCAP), whereas Anisakis crude extract ELISA detected 3.9% (2.4–6.0%) seropositives in fish processing workers, three (14%) of which showed IgE reactivity to milk proteins. The highest risk associated with Anisakis-sensitization among workers was fishing in the free time, rather than any of attributes related to the occupational exposure. Although no association was observed between anti-Anisakis seropositivity and wearing gloves or protective goggles, the majority of workers (92%) wore protective gloves, minimizing the risk for Anisakis sensitization via skin contact. Six HLA alleles within DRB1 gene were significantly associated with seropositivity under dominant, allelic or recessive models. All sera confirmed negative for anti-Trichinella spp. IgG. The study exhaustively covered almost all marine fish processing workers in Croatia, reflecting real-time Anisakis sensitization status within the industry, already under the influence of wide array of allergens.

Anisakiasis is a human disease caused by ingestion of live Anisakis spp. larvae by raw seafood. Fish processing and aquaculture workers (approximately 60 million people world-wide) are at occupational risk of becoming sensitized to Anisakis. This is the first study systematically evaluating the risk of Anisakis-sensitization in Croatian fish-processing workers and potential genetic susceptibility to anisakiasis in the analysed population. Observed seroprevalence was significantly higher in fish processing workers (1.8%) compared to the controls (0%). Surprisingly, the highest risk associated with Anisakis-sensitization among workers was fishing in their free time, rather than any of attributes related to the occupational exposure. While no association was observed between anti-Anisakis seropositivity and wearing gloves or protective goggles, the majority of workers (92%) wore protective gloves, minimizing the risk for Anisakis sensitization via skin contact. Additionally, seroprevalence to another important food-borne helminth, Trichinella spp. assessed in all Anisakis-positive subjects showed to be negative. Almost all marine fish processing workers in Croatia were part of this research, reflecting real-time Anisakis-sensitization status within the industry. This sets a baseline for the future tracking of sensitization in the sector already under the influence of wide array of allergens.

Development of a miniaturized protein microarray as a new serological IgG screening test for zoonotic agents and production diseases in pigs

In order to monitor the occurrence of zoonotic agents in pig herds as well as to improve herd health management, the development of new cost-effective diagnostic methods for pigs is necessary. In this study, a protein microarray-based assay for the simultaneous detection of immunoglobulin G (IgG) antibodies against different zoonotic agents and pathogens causing production diseases in pigs was developed. Therefore, antigens of ten different important swine pathogens (Toxoplasma gondii, Yersinia enterocolitica, Salmonella spp., Trichinella spp., Mycobacterium avium, Hepatitis E virus, Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, the porcine reproductive and respiratory syndrome virus, Influenza A virus) were spotted and covalently immobilized as 'antigen-spots' on microarray chips in order to test pig serum for the occurrence of antibodies. Pig serum was sampled at three German abattoirs and ELISA tests for the different pathogens were conducted with the purpose of creating a panel of reference samples for microarray analysis. To evaluate the accuracy of the antigens on the microarray, receiver operating characteristic (ROC) curve analysis using the ELISA test results as reference was performed for the different antigens. High area under curve values were achieved for the antigens of two zoonotic agents: Toxoplasma gondii (0.91), Yersinia enterocolitica (0.97) and for three production diseases: Actinobacillus pleuropneumoniae (0.77), Mycoplasma hyopneumoniae (0.94) and the porcine reproductive and respiratory syndrome virus (0.87). With the help of the newly developed microarray assay, collecting data on the occurrence of antibodies against zoonotic agents and production diseases in pig herds could be minimized to one measurement, resulting in an efficient screening test.

Immuno-proteomic analysis of Trichinella spiralis, T. pseudospiralis, and T. papuae extracts recognized by human T. spiralis-infected sera

The present study explored potentially immunogenic proteins of the encapsulated (Trichinella spiralis) and non-encapsulated (T. pseudospiralis, T. papuae) species within the genus Trichinella. The somatic muscle larval extracts of each species were subjected to immunoblotting analysis using human T. spiralis-infected serum samples. Fifteen reactive bands of all three species were selected for further protein identification by liquid chromatography-tandem mass spectrometry, and their possible functions were ascertained using the gene ontology. Our findings showed immunogenic protein patterns with molecular mass in the range of 33-67 kDa. Proteomic and bioinformatic analysis revealed a wide variety of functions of 17 identified proteins, which are associated with catalytic, binding, and structural activities. Most proteins were involved in cellular and metabolic processes that contribute in the invasion of host tissues and the larval molting processes. The parasite proteins were identified as actin-5C, serine protease, deoxyribonuclease-2, and intermediate filament protein ifa-1. This information may lead to alternative tools for selection of potential diagnostic protein markers or aid in the design of vaccine candidates for prevention and control of Trichinella infection.

Evaluation of the PrioCHECK™ Trichinella AAD Kit for the digestion and recovery of larvae in pork, horse meat and wild meat

The artificial digestion magnetic stirrer method using pepsin protease and hydrochloric acid is the standard assay for the detection of Trichinella larvae in muscle of infected animals. Recently, an alternative enzyme, serine protease, was employed in the development of a commercially available digestion kit (PrioCHECK™ Trichinella AAD Kit). This assay requires a higher digestion temperature of 60°C which kills the larvae during the digestion process, mitigating the risk of environmental contamination from the parasite. The present study was conducted to determine the performance of the PrioCHECK™ Trichinella AAD Kit compared to the conventional pepsin/HCl digestion. Replicate paired 115g samples of Trichinella-negative pork diaphragm and masseter, and of horse tongue and masseter, were used to compare the two methods for tissue digestibility. Similarly, paired 100g samples of pork diaphragm and horse tongue were spiked with proficiency samples containing known numbers of Trichinella spiralis first stage larvae to compare larval recoveries for the two methods. Masseter samples from wild bears and wolves naturally infected with Trichinella nativa or T6 were also used to compare the performance of the methods. The results of the study showed that the PrioCHECK™ Trichinella AAD Kit, when used according to the manufacturer's instructions, was effective in detecting Trichinella infection in all samples that contained 0.05 or more larvae per gram of tissue. Although there was no significant difference between the Kit method and the standard pepsin/HCl digestion procedure in the average number of larvae recovered from spiked pork diaphragm, 38% fewer larvae were recovered from similarly spiked samples of horse tongue by digestion using serine protease (one way ANOVA, P value <0.001). Additional clarification was also more often required for both horse meat and pork when using the Kit compared to the pepsin/HCl method. The results of testing wildlife samples were similar for the two methods. Overall, the performance of the Kit method was suitable for the digestion of muscle samples and recovery of Trichinella larvae, according to international standards. It also provides advantages of faster digestion, safer reagents and recovered parasites that are non-hazardous for analysts and the environment.

First Report of the Occurrence of Trichinella-Specific Antibodies in Domestic Pigs in Central and Eastern Uganda

Previous research on trichinellosis in Africa focused on isolating Trichinella from wildlife while the role of domestic pigs has remained highly under-researched. Pig keeping in Uganda is historically recent, and evidence on zoonotic pig diseases, including infection with Trichinella species, is scarce. A cross-sectional survey on Trichinella seroprevalence in pigs was conducted in three districts in Central and Eastern Uganda from April 2013 to January 2015. Serum from a random sample of 1125 pigs from 22 villages in Eastern and Central Uganda was examined to detect immunoglobulin G (IgG) against any Trichinella spp. using a commercially available ELISA based on excretory-secretory antigen. ELISA positive samples were confirmed using Western Blot based on somatic antigen of Trichinella spiralis as recommended in previous validation studies. Diaphragm pillar muscle samples (at least 5 g each) of 499 pigs from areas with high ELISA positivity were examined using the artificial digestion method. Overall, 78 of all 1125 animals (6.9%, 95% CI: 5.6-8.6%) tested positive for antibodies against Trichinella spp. in the ELISA at significantly higher levels in Kamuli district compared to Masaka and Mukono districts. Thirty-one percent of the ELISA positive samples were confirmed IgG positive by the Western Blot leading to an overall seroprevalence of 2.1% (95% CI: 1.4-3.2%). The large proportion of ELISA positive samples that could not be confirmed using Western blot may be the result of cross-reactivity with other gastrointestinal helminth infections or unknown host-specific immune response mechanisms in local pig breeds in Uganda. Attempts to isolate muscle larvae for species determination using the artificial digestion method were unsuccessful. Due to the large number of muscle samples examined we are confident that even if pigs are infected, the larval burden in pork is too low to pose a major risk to consumers of developing trichinellosis. This was the first large systematic field investigation of Trichinella infection in domestic pigs in Uganda and its results imply that further studies are needed to identify the Trichinella species involved, and to identify potential sources of infection for humans.

What lies within: coinfections and immunity

Helminth-induced immunomodulation is thought to influence the outcome of secondary infections. Osborne et al. (2014) and Reese et al. (2014) demonstrate that helminth infection impacts viral infections by tilting the immune system toward Th2/M2 immune regulatory responses that dampen Th1/M1 antiviral responses as well as promote reactivation of latent herpesviruses.

Trichinellosis surveillance--United States, 2008-2012

PROBLEM/CONDITION

Trichinellosis is a parasitic disease caused by nematodes in the genus Trichinella, which are among the most widespread zoonotic pathogens globally. Infection occurs following consumption of raw or undercooked meat infected with Trichinella larvae. Clinical manifestations of the disease range from asymptomatic infection to fatal disease; the common signs and symptoms include eosinophilia, fever, periorbital edema, and myalgia. Trichinellosis surveillance has documented a steady decline in the reported incidence of the disease in the United States. In recent years, proportionally fewer cases have been associated with consumption of commercial pork products, and more are associated with meat from wild game such as bear.

PERIOD COVERED

2008-2012.

DESCRIPTION OF SYSTEM

Trichinellosis has been a nationally notifiable disease in the United States since 1966 and is reportable in 48 states, New York City, and the District of Columbia. The purpose of national surveillance is to estimate incidence of infection, detect outbreaks, and guide prevention efforts. Cases are defined by clinical characteristics and the results of laboratory testing for evidence of Trichinella infection. Food exposure histories are obtained at the local level either at the point of care or through health department interview. States notify CDC of cases electronically through the National Notifiable Disease Surveillance System (available at http://wwwn.cdc.gov/nndss). In addition, states are asked to submit a standardized supplementary case report form that captures the clinical and epidemiologic information needed to meet the surveillance case definition. Reported cases are summarized weekly and annually in MMWR.

RESULTS

During 2008-2012, a total of 90 cases of trichinellosis were reported to CDC from 24 states and the District of Columbia. Six (7%) cases were excluded from analysis because a supplementary case report form was not submitted or the case did not meet the case definition. A total of 84 confirmed trichinellosis cases, including five outbreaks that comprised 40 cases, were analyzed and included in this report. During 2008-2012, the mean annual incidence of trichinellosis in the United States was 0.1 cases per 1 million population, with a median of 15 cases per year. Pork products were associated with 22 (26%) cases, including 10 (45%) that were linked with commercial pork products, six (27%) that were linked with wild boar, and one (5%) that was linked with home-raised swine; five (23%) were unspecified. Meats other than pork were associated with 45 (54%) cases, including 41 (91%) that were linked with bear meat, two (4%) that were linked with deer meat, and two (4%) that were linked with ground beef. The source for 17 (20%) cases was unknown. Of the 51 patients for whom information was reported on the manner in which the meat product was cooked, 24 (47%) reported eating raw or undercooked meat.

INTERPRETATION

The risk for Trichinella infection associated with commercial pork has decreased substantially in the United States since the 1940s, when data collection on trichinellosis cases first began. However, the continued identification of cases related to both pork and nonpork sources indicates that public education about trichinellosis and the dangers of consuming raw or undercooked meat still is needed.

PUBLIC HEALTH ACTIONS

Changes in domestic pork production and public health education regarding the safe preparation of pork have contributed to the reduction in the incidence of trichinellosis in the United States; however, consumption of wild game meat such as bear continues to be an important source of infection. Hunters and consumers of wild game meat should be educated about the risk associated with consumption of raw or undercooked meat.

[On the possibility of vertical transmission of Trichinella and the impact of its invasion]

Whether experimentally infected female rats can transmit Trichinella in utero and its invasion may affect the immunity of their offspring has been investigated. There is evidence that maternal antibodies have a significant impact on the humoral immunity of the offspring and as a result on the number of Trichinella larvae accustomed in the muscles. Immune interlayer formation in the populations of carnivorous mammals in the endemic areas occurs due to reinvasions and passive transmission of maternal antibodies to the offspring. High-tension immunity in the population and animals contributes to a reduction in the onset of invasion and to a predominance of the subclinical course of the disease and asymptomatic carriage in a specific focus. Passive immunity transmitted from the Trichinella-infected mother to its offspring is of importance in the development of epidemic and epizootic processes in the natural and synanthropic foci of trichinosis.

[The intensity of immune response to T. native antigen in the residents of coastal settlements in the Chukotka district, Chukotka Autonomous Okrug]

Sixty-three (24.3%) out of 259 residents of coastal settlements were found to have a positive immune response to Trichinella antigen. All the seropositive cases were represented by people belonging to three ethnic groups: Chukchi (97.8%), Eskimos (1.2%), and Yakuts (1.0%). The antibody titers varied from 1:100 (32.8%) to 1:1600 (8.7%). The highest titer reactivity was observed in marine mammal hunters, retired persons, and non-manual employees. There was a direct relationship between the antibody titer values and the dietary habits of the respondents preferring traditional foods prepared from marine mammal meat.

[Evaluation of Trichinella cross-reactions in the serological diagnosis of toxocariasis]

Toxocariasis caused by the nematode larvae of the Toxocara genus is a worldwide parasitic zoonosis. Diagnosis of human toxocariasis commonly relies on serological tests since the symptoms and signs of Toxocara infection are not pathognomonic. However Toxocara larval excretory-secretory (TES) antigen used in serological tests may exhibit low specificity due to the cross-reactions between related helminth infections such as ascariasis, anisakiasis, strongyloidosis and filariasis. In this study, we aimed to evaluate the possible effect of Trichinella cross-reactions in the serological diagnosis of toxocariasis by using ELISA and Western blot (WB) assay. For this purpose, sera samples of 209 trichinellosis patients who were definitely diagnosed during the Trichinella britovi outbreak occurred in İzmir in January 2004, were used. All the samples were screened initially by commercial Toxocara IgG-ELISA kit (Cypress Diagnostics, Belgium), then commercial Toxocara IgG-WB (Test-Line Diagnostics, Czech Republic) was applied to positive/ borderline-positive sera for confirmation. In our study, 94.3% (197/209) of the sera were found seronegative, while nine were positive and three were borderline. Thus a total of 12 (5.7%) sera were considered as seropositive by Toxocara IgG-ELISA. According to the results of WB, only one sera with the antigenic bands of 120 kDa, 32 kDa and 26 kDa in molecular weights was evaluated as positive. Four sera samples were found to be borderline. In three of border sera, the antigenic bands of 120 and 70 kDa in molecular weights were observed together and one sera had three (120, 70 and 32 kDa) different antigenic bands. Seven sera that had been found to be positive by ELISA was considered as negative by WB. While no bands was observed in four of these, three samples had an antigenic band of 120 kDa which had no diagnostic value when it was found alone. The results of our study showed that the crossreactivities between anti-Trichinella antibodies and TES antigens may be observed during Toxocara IgG ELISA assay. For that reason the positive Toxocara IgG-ELISA result should be confirmed by different tests such as WB for the definitive diagnosis of toxocariasis.

An enzyme-linked immunosorbent assay as screening tool for human intestinal capillariasis

Human intestinal capillariasis caused by Capillaria philippinensis is characterized by chronic diarrhea which may lead to death if left untreated. The mortality is highest among patients who are negative by conventional stool examination. Therefore this study explored the application of an enzyme-linked immunosorbent assay (ELISA) as a screening test for human intestinal capillariasis. The ELISA was developed using Trichinella spiralis soluble antigen for the detection of antibodies against C. philippinensis. A cut-off level at the upper 99% limit of the absorbance values of the healthy controls was established for positivity. All intestinal capillariasis sera showed positive ELISA, demonstrating 100% sensitivity, while all healthy control sera gave absorbance values below the cut-off level, resulting in 100% specificity. The ELISA was also positive with 75% of trichinellosis, 13.9% of strongyloidiasis, 9.1% of trichuriasis, and 4.2% of opisthorchiasis sera. The ELISA and immunoblot were in agreement in 91.1% of the sera tested. It was suggested that the here-presented ELISA is capable to detect intestinal capillariasis cases in endemic areas whose coproscopy is negative for worm eggs, larvae or adults.

Trichinellosis surveillance - United States, 2002-2007

PROBLEM/CONDITION

Trichinellosis is a parasitic disease caused by roundworms of the Trichinella genus. Humans are incidental hosts who become infected after ingestion of raw or undercooked meat containing encysted larvae of Trichinella spp. Common signs and symptoms of trichinellosis include eosinophilia, abdominal pain, fever, periorbital edema, and myalgia. National surveillance has documented a decline in the reported incidence of trichinellosis in the United States since 1947, the first year nationwide data were collected systematically. The decreased incidence of trichinellosis has mirrored the decrease of Trichinella in commercial pork products as a result of changes in pork industry management standards and government regulations. In addition, an overall decrease has occurred in the number of cases of trichinellosis related to pork consumption. During 1997-2001, meats other than pork were the most common source of infection, and more cases were associated with home-raised pork than with store-bought pork.

REPORTING PERIOD COVERED

2002-2007.

DESCRIPTION OF SYSTEM

Trichinellosis is a reportable disease in 48 states and has been a nationally notifiable disease since 1966. Cases are defined by clinical characteristics and the results of laboratory testing for evidence of Trichinella infection. States report cases to CDC through the National Notifiable Diseases Surveillance System. Reported cases are summarized weekly and yearly in MMWR. In addition, states are asked to submit a standardized case report form with supplementary case data to CDC's Division of Parasitic Diseases.

RESULTS

During 2002-2007, a total of 66 cases of trichinellosis were reported to CDC. Those cases for which a supplementary case report form was not submitted or that did not meet the case definition were excluded from analysis. Of the 66 cases reported during 2002-2007, a total of 12 (18%) cases were excluded from analysis. Associated meat products were classified as either pork or meat products other than pork and were identified for 43 (80%) cases. Meat products other than pork were associated with 27 (50%) cases: 21 with bear meat, one with either bear or deer meat, one with cougar meat, one with deer meat, one with walrus or seal meat, and two with commercial beef. Pork was associated with 10 (19%) cases: seven with commercial pork, two with noncommercial pork, and one with an unspecified type of pork. Of the seven cases associated with consumption of commercial pork, five were linked to U.S. commercial pork, and two were attributed to pork ingested during travel in Asia. The two cases associated with noncommercial pork were attributed to wild boar meat; one case involved wild boar meat from a farm and the other wild boar meat from a farmers' market. Six patients reported consuming both pork and meat products other than pork, but the infected meat product could not be identified.

INTERPRETATION

The number of reported trichinellosis cases attributed to commercial pork consumption remains low. The greatest number of cases continues to be associated with consumption of meat other than pork, especially bear meat.

PUBLIC HEALTH ACTION

For the incidence of trichinellosis in the United States to be reduced further, education regarding safe food preparation practices and prevention of trichinellosis should be targeted toward hunters and other consumers of wild game meat, especially bear.

[Trichinellosis serology in blood-donors from a non-endemic area of Argentina]

The aim of the present study was to determine the presence of human trichinellosis in an area of Argentina historically regarded as free of this parasitic disease. This parasitosis was assessed on 150 blood donors by means of immunoserological tests, and their relation with risk alimentary habits by a questionnaire. The questionnaires showed that 98.0% (n=147) of the individuals consumed pork and pork products at a high frequency. The main pork products incorporated to the habitual diet were the stuffed ones. A 80.3% (n=118) of the individuals had acquired such products at butchers, a 38.1% (n=56) at home slaughters and a 34.0% (n=50) at supermarkets. The immunoserological techniques employed were: enzyme immunoanalysis, indirect immunofluorescence and/or immunoelectrotransfer blot assay. Anti-Trichinella antibodies were detected in 8.0% (n=12) of the serum samples by more than one of the methodologies employed, considering these results as confirmatory of trichinellosis. The studies carried out herein demonstrate the existence of human trichinellosis in an area historically regarded as free of this parasitic disease and suggest its relationship with the ingestion of pork or pork products as a risk factor. These results indicate that the lack of reports should not be the only criterion for an area to be considered as Trichinella-free. The awareness of the existence of the parasite in a region will favor the establishment of control and prevention strategies which is of fundamental importance to avoid the spread of the disease.

Evaluation of inflammatory responses against muscle larvae of different Trichinella species by an image analysis system

The aim of this study was to evaluate the inflammatory response in the muscle tissue against Trichinella larvae of encapsulated (T. spiralis, T. britovi) and non-encapsulated (T. pseudospiralis) species. The inflammatory response was estimated in histological sections of muscle tissues from Trichinella-infected CD1 mice by a newly developed method. Nuclei were stained with one fluorescent probe, which binds nucleic acids with high affinity, and fluorescence was analysed by a software program. Evaluation of the relative fluorescence units was performed in both peri-capsular (close to the nurse cell-parasite complex) and extra-capsular (where the parasite was not visible) areas. The increase in the number of nuclei in the muscle tissues of Trichinella-infected mice was considered an inflammation marker, since uninfected muscles show low nucleus density. In order to evaluate differences in the nitrosylation pattern between encapsulated (T. spiralis, T. britovi) and non-encapsulated (T. pseudospiralis, Trichinella papuae, Trichinella zimbabwensis) species, L(1) larvae were tested by immunoblotting with an anti-nitrotyrosine polyclonal antibody. Inflammation induced by T. spiralis larvae in muscle tissues is statistically higher than that elicited by the other species, both in peri- and extra-capsular areas. Nitrosylation occurs at a higher level in encapsulated than in non-encapsulated species. The method developed in this work allows demonstration of differences in the host inflammatory response against encapsulated and non-encapsulated Trichinella species.

[Investigation on an outbreak of trichinosis and clinical analysis]

An outbreak of trichinosis occurred in Lhingchi Prefecture of Tibet with 9 cases identified among 10 people. They consumed collectively raw or undercooked pork. Two cases died because of misdiagnosis and mistreatment. In the 9 cases, 3 had eosinophilia, 3 showed positive anti-Trichinella IgG. Trichinella larvae were found in gastrocnemius muscle of 3 cases by biopsy including the 2 died cases.Seven cases were successfully treated with albendazole.

[Diagnostic efficiency of excretory-secretory Trichinella antigens in enzyme immunoassay]

The investigation deals with the enzyme immunodiagnosis of trichinosis in some mammalian species involved in the circulation of this widespread menacing anthropozoonosis in the natural synanthropic foci in the Russian Federation. The use of T. spiralis immunodominant antigens of a molecular mass of 63-29 kDa as enzyme immunoassay (EIA) diagnostic kits for the lifetime diagnosis may ensure a rather effective lifetime detected of the Trichinella-infested omnivores and carnivores (pigs and cats) participating in the circulation of the causative agent in the synanthropic foci. Also, these antigens are suitable for the study of the immunological aspects of tricinosis when T. spiralis invasion is simulated on laboratory animals (rodents). False-negative EIAs are associated with the specific features of immunological responsiveness of each organism, the degree of infectivity (immunological tolerance in intensive inoculation), the stage of invasion, the biological characteristics of a helminth (such as the immunosuppressive effect of the parasite on the host during larval migration), rather than with the quality of the used components of a response.

Contrasting effects of Trichinella spiralis and Trichuris muris antigens on the infection by Leishmania infantum in BALB/c mice

The interaction of Trichinella spiralis and Trichuris muris derived antigens with the infection by Leishmania infantum was investigated in BALB/c mice. Infection with 10(6) promastigotes of L. infantum did not induce relevant serum antibody (IgG subclasses), nor cytokine (IFN-gamma, IL-4) responses despite that mice could partially control the infection. Immunization with T. spiralis activated a moderate IgG1 and secondarily an IgG2a anti-leishmanial response whereas immunization with T. muris elicited only a weak and late activation of IgG1 anti-leishmanial response. Immunization with T. muris caused an elevation of serum IFN-gamma levels which was drastically reinforced by the L. infantum infection, and that was accompanied by almost complete parasitological cure of infected mice. Immunization with T. spiralis induced an elevation of serum IL-4 levels but this response was greatly (about 60%) neutralized by the infection with L. infantum, and this was associated to exacerbation of the infection.

Specific IgG4 response directed against the 45-kDa glycoprotein in trichinellosis: a re-evaluation of patients 15 years after infection

The aim of this study was to evaluate the humoral immune response in late human trichinellosis with particular attention to the presence of IgG4 antibodies directed against the Trichinella-45-kDa glycoprotein (gp). This study re-evaluates subjects 15 years after they were involved in a trichinellosis outbreak that occurred in Central Italy following the consumption of raw boar meat infected with Trichinella britovi. The results show that ELISA tests using the E/S antigen identified five IgM- and eight IgG-positive patients and no IgA-positive patients. Tests using immunoblot (IB) with E/S antigens identified three IgM-, five IgA-, seven- IgG1- and three IgG4-positive sera. When the purified 45-kDa gp was used as an antigen, the IB revealed that six of the ten sera tested were positive for IgG4. Sera were also evaluated with a commercial kit, revealing that 11 of 12 patients had a highly sensitive reactivity against Trichinella proteins (64 and 44-43 kDa). In conclusion, humoral immune response against Trichinella is still present in these patients 15 years after the initial infection, including an IgG4 response directed to the 45-kDa gp.

[Anti-Trichinella antibody level in muscle juice of experimentally infected mice]

OBJECTIVE

To detect the anti-Trichinella antibody level in muscle juice of experimentally infected mice and their correlation with serum antibodies.

METHODS

Two hundred and eighty-eight Kunming mice were randomly divided into 3 groups (96 mice each), each mouse was inoculated with 100, 300 or 500 muscle larvae of T spiralis, respectively. Anti-Trichinella antibodies in serum and muscle juice taken weekly up to 18 weeks post-infection (wpi) were detected by ELISA using T. spiralis muscle larval excretory-secretory (ES) antigens. Thirty mice were inoculated with T. spiralis muscle larvae(500 larvae each). The muscle samples taken in 6 wpi were kept in plastic containers and conserved at 4 degrees C for 7 days or at -20 degrees C for 20 weeks for detecting anti-Trichinella antibodies later.

RESULTS

Anti-Trichinella antibodies in muscle juice of the mice infected with 100, 300 or 500 larvae were detected in 4, 3 and 3 wpi, with antibody positive rate of 87.5%, 50% and 87.5% respectively. In the three groups of mice, the antibody positive rate of muscle juice increased gradually after infection and up to 100% in 6, 4 and 4 wpi, and the antibody level reached its peak in 8 wpi with an absorbance value of 0.43, 0.49 and 0.52 respectively. Thereafter, the antibody level decreased slightly, but the positive rate was still 100% and lasted to 18 wpi when the experiment was ended. The antibody level in muscle juice showed significant positive correlation with serum antibodies at different time intervals after infection in three groups (r100=0.940, r300=0.970, r500=0.983, P<0.05). The absorbance value of muscle samples conserved at 4 degrees C for 7 d and 1 d was the same (0.53) (F=0.250, P>0.05), and those conserved at -20 degrees C for 8 wk and 1 wk was 0.46 and 0.50 respectively, showing that the antibody level in muscle juice did not decreased considerably after the muscle samples were frozen at -20 degrees C for 8 weeks (F=2.273, P>0.05). The absorbance value of Trichinella-infected muscle conserved at -20 degrees C for 10 wk decreased to 0.43, with significant difference from that conserved at -20 degrees C for 1 wk, but the positive rate was also 100%, and antibodies were detected in all muscle samples conserved at -20 degrees C for 20 weeks when the experiment was ended.

CONCLUSION

When animals died or were slaughtered and serum samples could not be collected, muscle juice can be collected from fresh, cool and frozen meat and used as a substitute sample for detecting anti-Trichinella antibodies.

Human antibody recognition of Anisakidae and Trichinella spp. in Greenland

High levels of total IgE are observed among children in Greenland. To evaluate the extent to which Anisakidae and Trichinella spp. contribute to the high total IgE level, an ELISA and a western blot were developed for the detection of IgG antibodies to Anisakidae, based on excretory/secretory antigens from Anisakidae larvae. Western blots with Anisakidae and Trichinella antigens discriminated between Anisakidae and Trichinella infections, enabling cross-reactivity between the two parasite infections to be eliminated. Serum samples from 1012 children in Greenland were analysed for specific antibodies to Anisakidae and Trichinella. Eleven children were IgG-positive for Trichinella and nine were IgG-positive for Anisakidae, indicating a relatively low prevalence of both infections among children in Greenland. Faecal samples from 320 children were also examined for other intestinal parasites. Enterobius vermicularis was found in one sample and Blastocystis hominis in 32 samples, but no other intestinal parasites were identified. In total, 304 children had elevated total IgE levels. There was a significant association between Trichinella seropositivity and high levels of total IgE, but not between Anisakidae seropositivity and total IgE. The data indicate that parasitic infections alone do not explain the high level of total IgE observed among children in Greenland.

Trichinella: Differing effects of antigens from encapsulated and non-encapsulated species on in vitro nitric oxide production

Trichinellosis is a cosmopolitan zoonotic disease affecting a wide variety of animals, including man. Non-encapsulated and encapsulated species diverge with respect to their developmental strategies. Little is known at the molecular level about parasite-derived mediators responsible for host muscle cell transformation occurring during trichinellosis. In this context, host-parasite relationships in Trichinella-infected animals could be related to different host-immune and cell mediators, e.g. nitric oxide (NO). Here, we investigate the stimulatory/inhibitory role of L1 antigens from four encapsulated (T. spiralis, T. britovi, T. nelsoni and T. nativa) and one non-encapsulated (T. pseudospiralis) Trichinella species on NO production from rat macrophages in vitro. Our results demonstrate that encapsulated and non-encapsulated Trichinella species differ in their capacity to stimulate the secretion of NO from host macrophages. Biological significance of these differences should be further assessed in the available experimental models.

Heart- and skeletal muscle-specific antigens recognized by trichinellosis patient sera

The heart can be seriously affected in human trichinellosis, and cardiac involvement can cause death. Experimental infections in rats have suggested the possible participation of immunopathological processes. The aim of the present paper was to investigate the possible presence in trichinellosis patient sera of antibodies recognizing host tissues and particularly the myocardium. Nineteen sera from late period trichinellosis patients, who acquired infection in the Poznan region (Poland), were tested by immunoblot on extracts from normal rat or human heart ventricle wall, spleen, placenta, kidney and skeletal muscle. Patients' sera recognized several antigens that were not recognized by normal sera. On rat and human heart ventricle wall, a high proportion of sera (42%) reacted with a protein of 68 kDa (P < 0.05 compared to normal sera). The reactivity with this antigen, however, was not significantly different in patients with or without cardiac involvement. When sera were tested on skeletal muscle we found that 47% reacted with a protein of 27 kDa and 53% reacted with a protein of 41 kDa (P < 0.05 for both proteins, compared with normal sera). The reactivity against the 68 kDa antigen and against the 27 and 41 kDa skeletal muscle antigens was not observed on kidney, placenta and spleen extracts. Moreover, very few bands were observed on these tissues as compared to heart and skeletal muscle tissues, thus suggesting a high tissue specificity of the reactivity of trichinellosis sera. In conclusion, this study identifies organ-specific autoantibodies in trichinellosis patient sera, their role in the pathogenesis of cardiac involvement being still unclear.

Triquinosis: aspectos epidemiológicos, clínicos y de laboratorio. Estudio retrospectivo a 10 años (1994-2003)

BACKGROUND

Trichinellosis is a parasitic zoonosis caused by ingestion of infected meat containing cysts of Trichinella spp.

OBJECTIVES

To analyze the epidemiological, clinical and laboratory findings of trichinellosis patients in our center and compare the results with those from published series. To analyze the relationship between the clinical symptoms and laboratory findings.

MATERIALS AND METHODS

The clinical records of 127 patients were retrospectively analyzed.

RESULTS

Epidemiological: 61% were male and mean age was 32 years; 95% were associated with other cases. The food implicated was always pork. Clinical: 45% presented gastrointestinal symptoms and 98% systemic symptoms. Three patients required intensive care unit hospitalization and one died. In 53%, treatment consisted of associated antiparasitic and anti-inflammatory drugs. Laboratory: 59% presented leukocytosis and 72% absolute eosinophilia. Creatine phosphokinase was elevated in 62%, lactic dehydrogenase in 56% and glutamic-oxaloacetic transaminase (GOT) in 30%. Among 52 patients, 65% had positive serology; trichinoscopy of food samples was positive in three outbreaks. The population studied had a mean of 5 signs and/or symptoms. The patient group with more than 5 signs and/or symptoms presented higher white blood cell counts and GOT levels (p < 0.05)

CONCLUSIONS

Our results were comparable to those of other series; however, there was a low rate of complications. An association was found between a larger number of signs and symptoms and higher leukocyte counts and GOT levels. The relevance of these findings should be assessed in future studies. There is no agreement as to the best therapeutic option, a fact reflected in the various treatment modalities seen in our study.

Clinical and laboratory aspects of a trichinellosis outbreak in Izmir, Turkey

Epidemiological, clinical and laboratory data were collected during an outbreak of trichinellosis, which occurred in Izmir, Turkey, between January and March 2004. The source of the infection was raw meatballs made with a mixture of uncooked beef and pork. Of 474 persons who were admitted at the Ataturk Training and Research Hospital during this period with a history of raw meatball consumption, the diagnosis of trichinellosis was confirmed for 154 (32.5%, 87 males and 67 females; mean age 31 years, range 6-67 years). Among persons with a confirmed diagnosis, 79% had myalgia, 77% weakness and malaise, 63% arthralgia, 40% jaw pain, 68% fever, 63% periorbital and/or facial oedema, 49% oedema at the trunk and limb, 42% abdominal pain, 40% nausea and vomiting, 28% diarrhoea, 23% subconjunctival haemorrhage, 25% macular or petechial rash, 4% subungual haemorrhage, 15% cardiac complaints and 0.2% neurological complaints. Nine patients (5.8%) were hospitalised due to severe myalgia (n = 2), high fever (n = 3), neurological manifestations (n = 1), thrombophlebitis (n = 2) and palmar erythema (n = 1). Eosinophilia was present in 88% of the confirmed cases at the admission. Elevated levels of serum creatine phosphokinase, lactic dehydrogenase and aspartate aminotransferase were detected in 72%, 70% and 16% of the confirmed cases, respectively. The seroconversion occurred in most of the infected people between the 4th and 6th weeks after the infection. All of the confirmed cases were treated with mebendazole. People with severe symptoms were treated also with prednisolone (60 mg/day for three days) and those with a moderately severe clinical pattern received a non-steroid anti-inflammatory drug (naproxen sodium, 550 mg/day). All confirmed cases recovered without any clinical sequela.

Cell-mediated response at the muscle phase of Trichinella pseudospiralis and Trichinella spiralis infections

The cell-mediated response in BALB/c mice infected either by Trichinella pseudospiralis or Trichinella spiralis was compared at days 30-50 post-infection (muscle phase). The former species is non-encapsulated, whereas the latter is encapsulated in host muscles. The pattern of response against the two species was similar. Both species elicited T(H)0 or T(H)1/T(H)2 response, with the last one being dominant. Productions of interferon gamma (IFN-gamma), interleukin (IL)-4 and IL-5 were observed after antigenic restimulation of splenocytes from infected mice. No significant difference was observed between the levels of response to concanavalin A (Con-A) by the splenocytes from both infected and non-infected animals. There was a significant increase in serum IgG(1) and IgG(2a). Flow cytometric analysis revealed a marked proliferative response of splenocytes from infected mice to worm antigens, dominated by B (CD19) lymphoblasts. Only a few helper (CD4+) and cytotoxic (CD8+) T lymphoblasts were present. This was confirmed by an up-regulation of CD69, with a dominant expression on B lymphoblasts. In conclusion, the minimal or lack of intense cellular response against T. pseudospiralis in muscles is likely not due to depression of cell-mediated immunity.

Development and evaluation of an immunochromatographic strip for trichinellosis detection

In the present study, an immunochromatographic strip was developed for the serological detection of trichinellosis in swine. In the strip, the excretory-secretory (ES) antigens of Trichinella labelled with colloidal gold was used as the detector, and the staphylococcal protein A (SPA) and goat anti-ES antibody were blotted on the nitrocellulose membrane for the test and control lines, respectively. The evaluation of the strip was performed by comparing 60 clinical positive blood samples detected by the artificial digestion method with 46 serum samples from pigs infected with parasites other than Trichinella and 30 serum samples of parasite-free healthy pigs. The strip was shown to be of high specificity and sensitivity that were closely correlated with those of ELISA. Furthermore, the dipstick assay based on the strip is rapid (10 min) and easy to perform with no requirement of special skill, reagent or equipment. This suggests the immunochromatographic strip is an acceptable alternative to be used in clinical laboratories lacking specialized equipment as well as for field diagnosis.

Developmental checkpoints of the basophil/mast cell lineages in adult murine hematopoiesis

Basophils and mast cells, which are selectively endowed with the high-affinity IgE receptor and mediate a range of adaptive and innate immune responses, have an unknown developmental relationship. Here, by evaluating the expression of the beta7 integrin, a molecule that is required for selective homing of mast cell progenitors (MCPs) to the periphery, we identified bipotent progenitors that are capable of differentiating into either cell type in the mouse spleen. These basophil/mast cell progenitors (BMCPs) gave rise to basophils and mast cells at the single-cell level and reconstituted both mucosal and connective tissue mast cells. We also identified the basophil progenitor (BaP) and the MCP in the bone marrow and the gastrointestinal mucosa, respectively. We further show that the granulocyte-related transcription factor CCAAT/enhancer-binding protein alpha (C/EBPalpha) plays a primary role in the fate decision of BMCPs, being expressed in BaPs but not in MCPs. Thus, circulating basophils and tissue mast cells share a common developmental stage at which their fate decision might be controlled principally by C/EBPalpha.

Two-dimensional electrophoresis and mass spectrometry for the identification of species-specific Trichinella antigens

A proteomic approach was utilized for fine antigenic characterization of the closely related Trichinella genotypes Trichinella britovi T3 and Trichinella T8. Crude extract of muscle larvae L1 (LCE) from both isolates were analyzed by 2D-PAGE. Over 500 protein spots were reproducibly separated in both genotypes. These separated proteins were identified in Western blot with IgG1 and IgG3 from homologous and heterologous hyperimmune sera raised in BALB/c mice. A group of 20 and 15 spots migrating at 50--60 k Da and pH 5.5--6.5 in T. britovi and Trichinella T8 maps, respectively, reacted with the IgG1 from heterologous sera whereas a group of minor spots of similar migration patterns did not. Low cross-reactivity occurred for IgG3. MALDI-TOF and MALDI-TOF/TOF analysis of these antigens identified a predicted enolase, the protein P 49 and a predicted actin among the cross-reactive proteins and two hypothetical actins among the non cross-reactive proteins.

Re-evaluation of patients involved in a trichinellosis outbreak caused by Trichinella britovi 15 years after infection

This study re-evaluates 13 out of 48 subjects involved in a trichinellosis outbreak that occurred in Central Italy (Umbria Region) in 1988 resulting from the consumption of raw boar meat harboring Trichinella britovi. During the outbreak, 28 of 48 serologically positive subjects were asymptomatic, whereas 20 subjects presented one or more clinical signs including but not limited to fever, myalgia, periorbital oedema and conjunctivitis. Several patients were hospitalized with severe clinical signs requiring treatment with mebendazole and corticosteroids. Upon re-evaluation of 13 patients, none presented clinical signs; however, three still had increased CPK or LDH serum levels with some signs of electromyographic changes. In this study, enzyme immunoassays (EIA) were used to test the 13 positive sera for reactivity with T. britovi antigens using both excretory/secretory (E/S) antigens and a synthetic antigen composed of beta-tyvelose conjugated to bovine serum albumin. Western blots (WB) were also carried out using a commercial kit. Studies using EIA with E/S antigen identified five positive sera; however, using beta-tyvelose as antigen, only one positive sample was identified. Nearly all sera reacted positively with one or more Trichinella antigens when analyzed by WB, in particular to the 45 k Da beta-tyvelose containing glycoprotein. Results indicate that T. britovi, though less pathogenic than other Trichinella species, is clearly capable of inducing sustainable sequelae.

Anti-Trichinella antibodies detected in chronically infected horses by IFA and Western blot, but not by ELISA

In the Balkan countries, where trichinellosis is a re-emerging zoonosis, it is of great importance to determine Trichinella infection prevalence among the major hosts, including horses. One method for monitoring prevalence is serological surveillance; however, the validity of serological methods in horses is not well understood. The dynamics of anti-Trichinella IgG production and circulating excretory/secretory (ES) antigens were investigated in three horses experimentally-infected with Trichinella spiralis. Horses were slaughtered at 32 week post infection (p.i.). Low worm burdens were found in all three animals. Anti-Trichinella IgG was detected up to 32 weeks p.i. by an indirect immunofluorescence assay (IFA) and by Western blot (Wb), but not by ELISA. The ELISA test detected antibodies for only a short period of time (up to 18 weeks p.i. using ES antigen or up to 20 weeks p.i. using tyvelose-BSA antigen). The presence of circulating muscle larvae ES antigen in sera of infected horses was observed by dot blot from the 4th week p.i. up to the 32nd week p.i.

Comparison of two antigens for demonstration of Trichinella spp. antibodies in blood and muscle fluid of foxes, pigs and wild boars

For the surveillance of trichinellosis, the digestion method is reliable but also labour intensive. The serological methods for the detection of Trichinella-specific antibodies using ELISA offer a sensitive and relatively specific alternative. For serological studies, sera or plasma from blood samples are the most common source of antibodies, but although the concentration of antibodies is approximately 10-fold lower, muscle fluid can be a good alternative particularly for testing of wildlife samples. In the present study, an indirect ELISA technique was evaluated on both sera and muscle fluids from experimentally infected foxes, pigs, and wild boars using both excretory/secretory (E/S) antigens and a synthetic glycan antigen, beta-tyvelose. Although the synthetic antigen appears to be less sensitive than the E/S antigens, Trichinella-specific IgG antibodies were detected in both serum samples and muscle fluid samples from pigs, wild boars and foxes infected at levels which would be important for food safety or represent a significant reservoir for further transmission.

Trichinella infection in a hunting population of Papua New Guinea suggests an ancient relationship between Trichinella and human beings

A new Trichinella species, Trichinella papuae, was discovered in 11.5% of wild pigs in a remote region of Papua New Guinea. A survey was conducted to determine whether the inhabitants of this region are infected with Trichinella, as wild-pig meat represents their main source of protein. The prevalence of anti-Trichinella antibodies and its determinants were assessed among the inhabitants in 51 of the villages in the Morehead District of Papua New Guinea. We tested and interviewed 1536 people (28.8% of the adult population). Anti-Trichinella IgG were detected in 10.0% (95% Cl 8.5-11.6%) of them. The prevalence of seropositivity was higher in males (12.7%) than in females (7.5%) (P<0.01), and the seroprevalence significantly increased with age. In one area, seroprevalence was highest in villages nearest the hunting area in which wild pigs are infected with Trichinella papuae (P<0.01). Seropositivity was also correlated with the consumption of raw or undercooked meat. Persons reporting pain in the muscle joints and limbs were more likely to be seropositive; no severe clinical manifestations were observed. That infection was never severe suggests that the seropositive people are reinfected relatively often, but with very few larvae. If the epidemiological pattern of Trichinella infection observed among the hunting population of this area is any indication of the pattern of infection in prehistoric hunters, we can speculate that Trichinella infection due to the consumption of meat from wild animals was possibly a common disease among prehistoric populations.

Comparative dynamics and phenotype of the murine immune response to Trichinella spiralis and Trichinella pseudospiralis

Infection of NIH mice with Trichinella spiralis and Trichinella pseudospiralis results in qualitatively comparable immune responses. Antigen-specific proliferation by mesenteric lymph node cells was transient and temporally associated with intestinal infection, but in contrast was sustained throughout infection by splenocytes. Early cytokine production by mesenteric lymph node cells was dominated by interleukin 10, but also IL-5 and IL-4, with rapid resolution following parasite expulsion from the gut. Splenocytes showed a mixed profile of cytokine production, although again dominated by IL-10 and sustained over 60 days of infection. All antibody classes were evident, with early production of IgA and IgG1, and subsequent secretion of other subclasses including IgG2a. Granulocytic infiltration of the spleen was significantly greater in T. spiralis infection. The concentration of serum corticosterone generally remained within normal boundaries, although was raised by day 60 in T. spiralis-infected mice. We conclude that the systemic suppression of inflammation reported for T. pseudospiralis does not result from selective induction of regulatory cytokines, or a major difference in the immune response to infection with T. spiralis.

[Evaluation of three different ELISA kits for the diagnosis of trichinellosis]

Human trichinellosis caused by Trichinella spp. is a widely distributed parasitic disease, acquired by ingestion of undercooked or raw meat containing larvae of the parasite. In January 2004, a trichinellosis outbreak following the consumption of raw minced meat ball, occurred in Izmir, Turkey. In the present study, an in-house excretory/secretory (ES) IgG ELISA and two commercial IgG ELISA kits (Kit # I; IBL, Hamburg, kit # II; Cypress, Belgium) have been used to evaluate their diagnostic efficiencies in this outbreak. Serum samples were collected from 100 patients with trichinellosis, from 16 patients with other parasitosis and autoimmune diseases (2 toxocariasis, 8 hydatic cyst, 1 fascioliasis, 5 rheumatoid arthritis) and from 20 healthy subjects. While the sensitivity of in-house ELISA has been found as 100%, the sensitivities of commercial kits number I and II have been found as 75% and 48%, respectively. The specificities of these three tests have been detected as 93.7%, 87.5% and 100%, respectively. The results obtained in this study suggest that in-house ELISA is of significant diagnostic value for the diagnosis of trichinellosis.

[Preliminary study on congenital transmission of Trichinella spiralis in mice]

OBJECTIVE

To study congenital transmission of Trichinella spiralis in mice and observe the protection of anti-Trichinella antibodies from the infected dams to challenge infection.

METHODS

According to the gestation (fertilization), the Kunming mice were divided into two groups: the infected group after gestation and the gestated group after infection. New-born mice were cut into small pieces to separate the larvae within 1 day after birth. One-day-old offspring born to normal dams were nursed by the infected dams, slaughtered after 21 days and examined for the larvae. Serum anti-Trichinella antibody level in offspring born to the infected dams was assayed by ELISA at different time after birth, and its immune protection against challenge infection was studied.

RESULTS

Out of 6 offspring born to the dams infected at 7 days after fertilization, two were found to be infected. Among other female mice which were first infected with T. spiralis and then gestated, only the offspring born to the dams fertilized at 8 and 22 days after infection were found to be infected, the infection rate of offspring was 20% (2/10) and 25%(2/8) respectively. All larvae recovered from the young were non-encapsulated. The cross-fostering experiment showed that none of 30 offspring born to normal dams were found to be infected. The serum antibody positive rate in 27 offspring born to the infected dams at 1,7,24, and 40 days after birth was 100%, 100%, 77.8% and 14.8%, respectively. The worm reduction rate in the offspring 40 days after birth was 62.0% after challenge infection. The worm reduction rate in mice in which sera from the offspring born to the infected dams were passively transferred was 55.7%, there was a significant difference (P<0.01) compared to the control group.

CONCLUSION

A transplacental transmission of T. spiralis is revealed in mice. Anti-Trichinella antibodies from the infected dams may partially protect the young from challenge infection.

[Current knowledge on human trichinellosis]

Until the beginning of the nineties, the control of trichinellosis was thought to be a solved problem in Europe. However, as a consequence of social, economical and ecological changes in Central Eastern and Eastern Europe in the past decade, trichinellosis became a re-emerging infectious disease in the region. Molecular genetic studies demonstrated that at least two Trichinella species can be responsible for trichinellosis outbreaks in the region, and the epidemiology of trichinellosis is more complex than previously thought. Although Trichinella spiralis has been successfully eradicated in Hungary, it was recently demonstrated that Trichinella britovi persists in the sylvatic cycle. In view of the considerable epidemiological changes in the region, the aim of this review is to summarise the current knowledge on the clinical aspects of human trichinellosis.

Serosurvey of selected zoonotic agents in polar bears ( Ursus maritimus )

Between 1982 and 1999 blood samples were collected from 500 polar bears (Ursus maritimus) captured in the Beaufort and Chukchi seas, to determine the seroprevalence of Brucella species, Toxoplasma gondii, and Trichinella species infections. The bears were classified into four age groups, cubs, yearlings, subadults and adults. Brucella and Toxoplasma antibodies were detected by agglutination (a buffered acidified card antigen and rapid automated presumptive test for brucellosis and a commercial latex agglutination test for toxoplasmosis); an ELISA was used to detect Trichinella antibodies. The overall seroprevalence of Brucella species was 5 per cent, and subadults and yearlings were 2-62 times (95 per cent confidence interval 1.02 to 6.82) more likely to be seropositive for Brucella species than adults and their cubs. The antibody prevalence for Toxoplasma gondii was 6 per cent, and for Trichinella species 55.6 per cent. The prevalence of antibodies to Trichinella species increased with age (P<0.001).

Influence of methods for Trichinella detection in pigs from endemic and non-endemic European region

A total of 1401 German and 226 Croatian pigs raised either indoors or outdoors were tested for Trichinella infection by direct and indirect detection methods. A 10 g sample of diaphragm were examined for muscle larvae by the artificial digestion method; the species was determined by multiplex polymerase chain reaction (PCR). For detection of anti-Trichinella IgG, serum samples diluted 1:100, and meat juice samples diluted 1:10, were tested by enzyme-linked immunosorbent assay. All German pigs and those Croatian pigs raised indoors proved to be Trichinella-negative by all methods. Muscle larvae were detected in a total of eleven of the Croatian pigs, which were raised on small outdoor farms. For eight isolates, PCR results demonstrated that recovered larvae were Trichinella spiralis. Anti-Trichinella-IgG was detected in serum and meat juice of digestion positive animals when the worm burdens exceeded 0.38 larvae per gram of muscle. Positive results in Croatian pigs indicate a higher risk of infection for outdoor farming in areas where Trichinella is endemic. Results of direct and indirect detection were compared and are discussed with special regard to specificity and sensitivity of methods.

Comparison of synthetic tyvelose antigen with excretory-secretory antigen for the detection of trichinellosis in swine using enzyme-linked immunosorbent assay

Two enzyme-linked immunosorbent assay (ELISA) systems, one using natural excretory-secretory (ES) antigens and the other a synthetic glycan antigen (3,6-dideoxy-D-arabinohexose [tyvelose, TY]), were evaluated for the serological diagnosis of trichinellosis in swine. Sensitivity was estimated using samples (n = 113) collected 3-21 wk PI from 15 experimentally infected pigs, and specificity was estimated using samples (n = 397) from a population of Trichinella spp.-free pigs. Results were analyzed using 2 cutoff values recommended in international guidelines (Office Internationale des Epizooties [OIE]) and by the optimal cutoff level as determined by receiver-operator characteristic (ROC) analysis. The ROC-optimized TY-ELISA consistently performed better than all other combinations. None of the combinations of test and cut-off detected infected pigs sooner than 35 days; however, the ROC-optimized TY-ELISA identified 8 of 15 pigs earlier than the ES-ELISA and detected 2 pigs missed by all other tests. At 49 days PI the sensitivity and specificity of the ROC-optimized TY-ELISA were 94.3 and 96.7%, respectively, as compared with the ROC-optimized ES-ELISA at 84.9 and 96.0%, respectively. The ROC-optimized TY-ELISA was 100% specific at OIE-recommended cut-offs. This study indicates that the TY-ELISA is as good or better than the ES-ELISA for the detection of trichinellosis in swine.

International Commission on Trichinellosis: recommendations on the use of serological tests for the detection of Trichinella infection in animals and man

The use of serological tests to detect Trichinella infection in domestic and wild animals and in humans has not been standardised yet. This review provides an uniform set of recommendations for the development and use of serological tests to detect circulating antibodies in serum samples. The recommendations are based on the best scientific published information and on the unpublished data from laboratories with a great expertise in this field and represent the official position of the International Commission on Trichinellosis regarding acceptable methods and the evaluation of the sensitivity and specificity. These recommendations are subject to change as new scientific information becomes available.

[Trichinellosis outbreaks in Spain (1990-2001)]

INTRODUCTION

Trichinellosis is a helminth infection having a wide geographical distribution. It is acquired by ingestion of raw or undercooked meat infected with Trichinella spp. The present work reviews the human trichinellosis outbreaks recorded in Spain during 1990-2001, taking into account both the geographical distribution and source of the infection.

METHODS

The parasite was isolated from suspected meats with the digestion technique. Molecular characterization of Trichinella isolates was done by random amplified polymorphic DNA (RAPD) analysis and Western-blot with US5 and US9 monoclonal antibodies. Anti-Trichinella antibodies in the patients' sera were investigated by indirect immunofluorescence (IIF).

RESULTS

A total of 49 trichinellosis outbreaks were detected in Spain during 1990-2001, 75.5% produced by ingestion of infected wild boar, 14.3% by infected domestic pig and 10.2% by an unknown source. Of the 49 outbreaks, 21 were followed up in our laboratory. We were able to perform molecular identification of the Trichinella species involved in 13 outbreaks, with 61.5% produced by T. britovi and 38.5% by T. spiralis. Serological diagnosis of the trichinellosis patients by IIF allowed confirmation of helminth infection.

CONCLUSIONS

With the use of molecular markers, T. spiralis and T. britovi were identified as the causative organisms in trichinellosis outbreaks detected in Spain during 1990-2001. These results reveal the importance of T. britovi in Spanish public health.

Minor interspecies variations in the sequence of the gp53 TSL-1 antigen of Trichinella define species-specific immunodominant epitopes1

Among the Trichinella TSL-1 antigens, whose antigenicity is generally due mainly to tyvelose-containing epitopes, gp53 is unusual in that its antigenicity is due mainly to protein epitopes. In the present study we mapped two of these epitopes, recognized by monoclonal antibodies (mAbs) that specifically recognize gp53 from all encysting Trichinella species (mAb US9), or gp53 from Trichinella spiralis alone (mAb US5). Based on previously published sequences of this glycoprotein [Mol. Biochem. Parasitol. 72 (1995) 253], in this study, we cloned the full gp53 cDNA from a new strain, Trichinella britovi (ISS 11; AN: ), and from another T. spiralis isolate (ISS 115; AN: ). The gp53 sequence comprised an ORF of 1239bp, coding for 412 amino acids, with 61 nucleotide differences (resulting in 38 residue changes) between the two species. Mapping of US5- and US9-recognized epitopes was undertaken through the construction and expression in the pGEX4T vector of truncated gp53 peptides, and by the construction of peptides derived from the antigenic regions. The epitope recognized by mAb US9 was a linear peptide of 8 residues, 33Met- 40Ser, located in the amino-terminal region, while the corresponding epitope recognized by mAb US5 was a 47-amino acid sequence containing two alpha-helix regions flanked by random coils, 290Thr- 336Lys. Molecular modeling of these peptides seems to indicate that recognition of the US9 epitope depends on the presence of two available hydroxyl groups provided by one methionine and one serine on T. spiralis gp53 (not present on Trichinella pseudospiralis gp53). Additionally, the stability of the US5 epitope seems to depend on correct folding of the 47-amino acid sequence (only present in T. spiralis). The relevance of these findings for understanding the antigenic recognition of Trichinella TSL-1 antigens, and for further studies to investigate possible function(s) of gp53 in Trichinella, is discussed.

Nitric oxide synthase immunoreactivity in the nematode Trichinella britovi. Evidence for nitric oxide production by the parasite

Nitric oxide has been extensively studied as an effector molecule of the host immune response against both protozoa and helminths, but parasites can also produce this molecule, through the action of nitric oxide (NO) synthases or NO synthases-like enzymes. The aim of this study was to verify the possible production of NO by Trichinella britovi L(1) larvae and the enzymes involved in this process. The NO synthase immunoreactivity and putative nitric oxide synthase-activity was analysed using antibodies to mammalian NO synthase III and to nitrotyrosine with immunohistochemistry, gold immunocytochemistry and immunoblot analysis and NADPH-diaphorase histochemistry. Our results show that T. britovi L(1) larvae possess an enzymatic activity capable of producing NO. The localisation of this activity, according to the NADPH-diaphorase histochemistry, is both at the cuticular and the internal level. This localisation is confirmed by nitrotyrosine immunohistochemistry both under optical and electron microscopy. Using the NO synthase III antibody, a similar pattern of labelling was found: in particular, electron microscopy showed a localisation of this immunoreactivity in the cuticle and in the stichocytes, where only the alpha2 granules contained gold particles, mainly concentrated at their periphery. Four polypeptides reacting to the NO synthase III antibody are revealed by Western blotting. Their molecular weight ranged from 38 to 50 kDa. A significant reaction of the anti-nitrotyrosine antibody to polypeptides 95, 60, 48 and 39 kDa from the same sample suggested the presence of different nitrosylated proteins.