New aspects of human trichinellosis: the impact of new Trichinella species

Trichinellosis is a re-emerging zoonosis and more clinical awareness is needed. In particular, the description of new Trichinella species such as T. papuae and T. murrelli and the occurrence of human cases caused by T pseudospiralis, until very recently thought to occur only in animals, requires changes in our handling of clinical trichinellosis, because existing knowledge is based mostly on cases due to classical T spiralis infection. The aim of the present review is to integrate the experiences derived from different outbreaks around the world, caused by different Trichinella species, in order to provide a more comprehensive approach to diagnosis and treatment.

Focus of human trichinellosis in Papua New Guinea

Human trichinellosis and teniasis (Taenia solium) are meat-borne helminthic infections with a wide distribution throughout the world. However, there is little information on the prevalence of these infections in Papua New Guinea. In 1999, serum samples were collected from 97 people in 6 villages in the remote Bensbach area of Papua New Guinea. Enzyme-linked immunosorbent assay and Western blot analyses were used to detect anti-Trichinella immunoglobulin (Ig) G and anti-cysticercus IgG in this population. The prevalence of Trichinella antibodies among inhabitants of the Bensbach area was 28.9% (28 of 97; 67.8% in men), suggesting a high consumption of poorly cooked meat. The higher prevalence of infection for Trichinella in men compared with women may be explained by the inclination of men to eat undercooked pork while hunting. All serum samples were negative for cysticercus antibodies. This is to our knowledge the first serosurvey showing anti-Trichinella antibodies in a human population living in Papua New Guinea (Australian region).

Clinical appraisal of patients and detection of serum antibodies by ELISA and CIA tests in late periods of Trichinella sp. invasion

Results of our studies using ELISA and competitive inhibition assay (CIA) tests fully confirmed the previously experienced trichinellosis and reflected persistent stimulation of antibody production due to the antigen release from Trichinella larvae, which had survived longer and undergone gradual destruction in the muscles. The studies proved that the tests complement each other, yielding concordant results in 86.7% of cases. Due to its higher specificity, the CIA test can help in interpreting pathological signs/symptoms and in evaluating humoral response activity at late and distant in time periods following the invasion.

The use of a synthetic antigen for the serological diagnosis of human trichinellosis

Hosts infected with Trichinella produce antibodies specific for an epitope common to the TSL-1 family antigens. This epitope contained uncommon terminal 3, 6-dideoxy-D-arabinohexose (so called tyvelose) residues. The disaccharide moiety was synthesized and an immunodiagnostic assay was developed, which was specific and sensitive in swine trichinellosis. We aimed to verify the specificity and sensitivity of this immunodiagnostic test in human trichinellosis. 15 sera from normal subjects, 12 from patients with other parasitic diseases and 50 from trichinellosis patients were tested. Indirect enzyme linked immunosorbent assay (ELISA) for specific IgG and an amplified ELISA for specific IgE were performed using beta-tyvelose-GalNAc-bovine serum albumin (BSA) disaccharide conjugate or T. spiralis muscle larvae excretory/secretory (E/S) products, as antigens. Neither control sera nor other parasitic infection sera resulted positive both for IgG and IgE when synthetic or E/S antigens were used. In trichinellosis patient sera, specific IgG were present in 100% of cases, irrespective of the antigen used, but whereas specific IgE were detected in 78% using E/S antigens, a 100% positivity rate was obtained, using the beta-tyvelose-BSA conjugate.

Modulation of human immune response by Echinococcus granulosus antigen B and its possible role in evading host defenses

By directly suppressing the function of certain immune cell subsets and by stimulating other cell populations related to immunopathology, parasite-derived substances play an important role in the chronic establishment of parasitic disease. Our objective was twofold: (i) to investigate further the role of Echinococcus granulosus antigen B (AgB) in the human early inflammatory response by determining its effect on polymorphonuclear cell (PMN) random migration, chemotaxis, and oxidative metabolism and (ii) to determine its action in acquired immunity by evaluating AgB and sheep hydatid fluid (SHF)-driven Th1 (gamma interferon [IFN-gamma] and interleukin 12 [IL-12]) and Th2 (IL-4 and IL-13) cytokine production by peripheral blood mononuclear cells (PBMC) from 40 patients who had cured or stable or progressive cystic echinococcosis. AgB significantly inhibited PMN recruitment but left their random migration and oxidative metabolism unchanged. Patients' PBMC stimulated with AgB produced IL-4 and IL-13 but did not produce IL-12. They also produced significantly lower IFN-gamma concentrations than did PBMC stimulated with SHF (P = 10(-5)). AgB skewed the Th1/Th2 cytokine ratios towards a preferentially immunopathology-associated Th2 polarization, predominantly in patients with progressive disease. AgB-stimulated patients' PBMC also proliferated less than SHF-stimulated PBMC (P = 9 x 10(-3)). In vitro Th2 cytokine production was reflected in vivo by elevated specific immunoglobulin E (IgE) and IgG4 antibodies binding to AgB. These findings confirm that AgB plays a role in the escape from early immunity by inhibiting PMN chemotaxis. They also add new information on the host-parasite relationship, suggesting that AgB exploits the activation of T helper cells by eliciting a nonprotective Th2 cell response.

Randomized comparison of intranasal and transdermal estradiol

OBJECTIVE

To compare the efficacy and patient acceptability of intranasal versus transdermal 17 beta-estradiol (E2) delivery systems for postmenopausal symptoms.

METHODS

Postmenopausal women were randomly assigned to intranasal 17 beta-E2, 300 microg daily (n = 176) or transdermal 17 beta-E2 (delivering 50 microg/day), two patches per week (n = 185) for 12 weeks, followed by a 4-week period with the alternate treatment. Efficacy was compared between groups using the Kupperman Index and vasomotor symptoms at week 12. Patient acceptability was compared by patient choice of administration route and by questionnaire at week 16.

RESULTS

Intranasal and transdermal therapy produced significant reductions in the Kupperman Index and in the occurrence of hot flushes and night sweats at week 12. Alleviation of climacteric symptoms was statistically equivalent in the two treatment groups (P <.001). The difference between groups in the Kupperman Index score of -0.5 +/- 0.9 (95% confidence interval -2.3, 1.3) was within the predetermined interval of equivalence. Both therapies were well tolerated with similar adverse event rates, except for moderate and severe mastalgia which was significantly less frequent with intranasal E2 (7.2%) than with the patch (15.5%, P =.02). Sixty-six percent of patients chose to continue the intranasal therapy and 34% the transdermal therapy (P <.001). Satisfaction was greater with intranasal therapy at week 16 (P <.001).

CONCLUSION

Intranasal and transdermal estrogen delivery systems had equivalent efficacy and similar safety profiles. Intranasal therapy was the patients' choice for long-term treatment.

Lymphocyte subsets in hemodialyzed HCV+ and HCV- patients

The aim of our study was to get information on the immune status of patients who undergo haemodialysis in the presence of an HCV infection. This virus infects not only hepatocytes, but also blood mononuclear cells, in particular B cells [1], but we do not know the role of this lymphocyte involvement in the maintenance and progression of hepatitis. The impairment of the cell-mediated immune response in uraemic patients is well known, for example only 50–60% of uraemic patients undergo a seroconversion after HBV vaccine, compared to 95% of the normal population. Paradoxically the immunodeficiency is concomitant with an activation of related cells which is increased rather than ameliorated by the dialysis treatment [2]. In these patients lymphocytopenia is also present with a reduction of the absolute number of T lymphocytes which remain normal in percentage. The study was performed on the following groups of subjects.

Inhibitory effects of human neutrophil functions by the 45-kD glycoprotein derived from the parasitic nematode Trichinella spiralis

AIM

We evaluated the effect of the 45-kD protein of Trichinella spiralis (gp45), purified by affinity chromatography, on random migration and chemotaxis, the oxidative metabolism of human neutrophils and on the CD11b upregulation induced by formyl-methionyl-leucyl-phenylalanine (f-MLP).

METHODS

Donor neutrophils incubated with different amounts of gp45 (0.5, 1, 1.5, 2 microg/ml) or buffer and the random migration and chemotaxis, evaluated by means of a special technique of image analysis, and the chemiluminescence response to f-MLP or phorbol myristate acetate (PMA) were analyzed. The effect on CD11b upregulation was assessed incubating cells with the protein, when activating them with f-MLP.

RESULTS

The results showed that gp45 inhibited both random and stimulated migrations, and reduced the response to f-MLP and PMA. Furthermore, gp45 significantly reduced the upregulation of the CD11b induced by f-MLP.

CONCLUSION

The results show that gp45 inhibits PMN in different functions, suggesting an anti-inflammatory action.

[Echolaparoscopy in the staging of abdominal neoplasms. Prospective study]

OBJECTIVE

To evaluate the sensitivity, specificity, positive and negative predictive value and influence on surgical strategy of laparoscopy and laparoscopic ultrasound on staging of abdominal malignancies.

MATERIAL AND METHODS

Prospective evaluation of laparoscopic ultrasound staging, according to the TNM classification, of 80 consecutive cases of abdominal malignancies in terms of sensitivity, specificity, positive and negative predictive value and influence on surgical strategy. Pathologic examination of final surgical specimens or laparoscopic biopsies was used as control.

RESULTS

Laparoscopic ultrasound evaluation was carried out successfully in 95% of cases with no mortality and morbidity. Twenty one out of 76 patients (28%) had their stage changed based on laparoscopic ultrasound findings. Unnecessary laparotomy was avoided in 11 cases (14%) due to evidence of advanced disease at laparoscopic ultrasound. For pancreatic cancer laparoscopic ultrasound was more sensitive for TNM, specificity was higher just for nodal evaluation. For liver tumor laparoscopic staging revealed more sensitive for N and M evaluation. Laparoscopic ultrasound staging had low specificity and sensitivity for T evaluation, while it was more sensitive and specific than clinical staging for nodal and distant metastasis assessment respectively for gastric and colon cancer.

CONCLUSION

Laparoscopic ultrasound staging is a safe, feasible and effective staging tool for several abdominal malignancies. The introduction of laparoscopic ultrasound probes overcomes the lack of tactile sensation proper of laparoscopy, allowing precise evaluation of both solid and deeply located abdominal structures. The use of laparoscopic ultrasound staging may help to reduce the number of unnecessary laparotomies.

Immunochemical and molecular characterization of vertebral hydatid fluid

This study describes a 42-year-old male born in Tunisia, who presented with vertebral hydatidosis which was initially misdiagnosed as Pott's disease. The correct diagnosis was finally made utilizing CT and MRI imaging and confirmation of the diagnosis was made possible by molecular and immunochemical characterization of the content of vertebral cyst fluid.

The sacrospinous vaginal vault suspension: Critical analysis of outcomes

One hundred and three women with a preoperative diagnosis of a pelvic support defect underwent right sacrospinous fixation of the vaginal apex. The procedure was performed either therapeutically (in 63 subjects with vaginal vault eversion) or prophylactically (40 patients with severe uterovaginal prolapse), and was associated with other reconstructive procedures to repair the coexisting cystocele, enterocele or rectocele. Preoperative and postoperative assessments of each vaginal site were compared and the results in the cure of stress urinary incontinence, if present, were evaluated with regard to the type of surgery performed. The overall rate of satisfactory results in the repair of the superior vaginal defect was 94%, and good anatomic results were achieved in the repair of either enterocele or rectocele. Conversely, the repair of the anterior vaginal wall was not as good as in the posterior and superior vaginal sites. Stress urinary incontinence was successfully managed in 72% of the women using different anti-incontinence procedures.

Anaphylactic response to parasite antigens: IgE and IgG1 independently induce death in Trichinella-infected mice

The response of animals infected with different Trichinella species (T. spiralis, T. britovi, T. pseudospiralis) to antigens of different Trichinella species was evaluated in outbred mice (CD1) and inbred mice (BALB/c, C3H, SJL, C57BL/6). In mice deficient for IgE or IgG1, T. spiralis only was used. In homologous conditions (i. e., same Trichinella species for antigens and infectious agent) mortality was very high (up to 100% in SJL and C57BL/6). The anaphylactic response in heterologous conditions was much lower and death was observed only in C57BL/6 and SJL mice. Experiments with deficient mice have shown that both specific IgE and IgG1 independently induce a fatal anaphylactic response.

Effects of oral and transdermal hormone replacement therapy on lipoprotein(A) and lipids: a randomized controlled trial

OBJECTIVE

Our purpose was to compare the effect of oral and transdermal hormone replacement therapy on lipoprotein(a) and other plasma lipids in healthy postmenopausal women.

DESIGN

A total of 120 postmenopausal women were enrolled in a prospective randomized controlled study, and allocated either to transdermal 17 beta-estradiol (50 micrograms/day) or to oral conjugated estrogen (0.625 mg/day). Forty-one age-matched women were used as the reference group. Plasma lipids and lipoproteins were determined every 3 months and differences were sought by statistical analysis.

RESULTS

Plasma lipoprotein(a) dropped after 3 months of treatment either with transdermal estradiol (p < 0.01) or oral estrogen (p < 0.01). Lipoprotein(a) was reduced by 12% and 22%, respectively. No further decreases were seen later on. Plasma total and low-density lipoprotein (LDL) cholesterol concentrations were decreased significantly with both treatments after 3 months of therapy. No difference was seen in the lowering effect on lipoprotein(a), LDL and total cholesterol concentrations between regimens. Plasma high-density lipoprotein (HDL) cholesterol and triglyceride concentrations increased throughout the study only in patients treated with oral estrogen.

CONCLUSIONS

These data demonstrate that hormone replacement therapy reduces the concentration of lipoprotein(a) when given both orally and transdermally. The lowering effect is achieved quickly because the maximal effect is observed after 3 months of therapy.

[Modulation of inflammatory cells in helminth infections]

In this review, different mechanisms by which helminthic parasites modulate the activities of inflammatory cells are considered. Examples are presented of parasitic products interfering with lymphocytes and their products such as antibodies, then modifying both regulation and effector response of the immune system. Furthermore, examples of interference on the complement system are illustrated. Parasites such as Ancylostoma caninum produce factors such as the neutrophil inhibitory factor (NIF) capable of inhibiting the neutrophil-endothelium adhesion, whereas Trichinella spiralis produces a glycoprotein, the 45gp, which inhibits different neutrophil functions. Parasites are also able to modulate the function of the monocytes-macrophages which in some infections play a crucial role; the modulation of NO synthesis is also relevant to the host-parasite relationship. Finally, the different anti-oxidant systems of helminthic parasites are described. The comprehension of such evasion mechanisms of the immune response is necessary to develop vaccines and new drugs, but it is also useful to clarify the contribution of parasites to immune system evolution.

Immunopathological mechanisms underlying the time-course of Trichinella spiralis cardiomyopathy in rats

The present study shows that isolated, perfused hearts from rats orally infected with Trichinella spiralis have a reduced left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF). This reduction is considerably enhanced by a single bolus (100 pM) of PAF (platelet activating factor, an eosinophil activator), especially at 21 days post-infection (d.p.i.), which is the time of the maximum increase in blood and tissue eosinophilia. Helminthic DNA analysis shows that, from 21 d.p.i. onwards, the morphological and functional changes in the myocardium cannot be ascribed to the parasite's presence, whereas its antigens and the attendant immunopathological reactions might have a role in the induction of myocardial damage and dysfunction. Some perivascular inflammatory cells (eosinophils and mast cells) appear to undergo degranulation. All these data suggest a complex sequence of events, from acute myocarditis (21 d.p.i.) which may lead in time (48 d.p.i. onwards) to a dilating cardiomyopathy.

Hexosaminidase in Trichinella spiralis is a single protein with alpha- and beta-subunits catalytic activities

Beta-N-acetylhexosaminidase is expressed as a single protein in Trichinella spiralis and has catalytic properties similar to the alpha- and beta-subunits of human and mouse isoenzymes A and B. It can hydrolyze the artificial substrates, 4-methylumbelliferyl-beta-D-glucosamine and 4-methylumbelliferyl-beta-D-glucosamine-6-sulphate which are respectively hydrolyzed by the beta- and alpha-subunits. The enzyme is thermostable, has a basic isoelectric point, and thus is similar to the B isoenzyme. Northern blotting experiments indicate that the enzyme is encoded by a single gene. Hexosaminidase from Trichinella spiralis shows that the substrate specificities of alpha- and beta-subunits precede the duplication of their genes.

[Trichinellosis approaching the year 2000]

Relevant information is given on the Ninth International Conference on Trichinellosis held in Mexico City from 19 to 22 August 1996. The Conference was organized in 4 Symposia and 8 Workshops. One-hundred-thirty scientific contributions (on the epidemiology, biology, systematics, immunology, biochemistry, molecular biology, pathology, legislation and control) were presented by 90 research scientists coming from 21 countries.

Lipoprotein(a) and other lipids after oophorectomy and estrogen replacement therapy

OBJECTIVE

To assess the effect of surgical menopause and subsequent estrogen replacement therapy (ERT) on lipoprotein(a) [Lp(a)] and common lipids.

METHODS

In 24 healthy premenopausal women, lipids (total cholesterol, low-density lipoprotein [LDL] and high-density lipoprotein [HDL] cholesterol, and triglycerides) and gonadotropins (FSH, LH) were measured the day before hysterectomy with bilateral oophorectomy and then after 1, 2, and 3 months. Blood was also drawn after 2, 4, 6, and 15 days to exclude the effect of surgery on Lp(a). In 19 women who volunteered for ERT, the lipid profile was assayed again after 3, 6, and 12 months of treatment.

RESULTS

Lipoprotein(a) levels rose significantly over the 3 months after surgery, from a mean +/- standard deviation (SD) 5.7 +/- 6.1 mg/dL to 10.4 +/- 9.2 mg/dL. Total cholesterol and LDL cholesterol levels increased significantly over the first 2 months; HDL cholesterol decreased significantly during the 3 months of follow-up (by 10, 17, and 20%) (P < .001). Plasma triglycerides did not change after surgery. Three months following ERT, Lp(a) and total cholesterol were significantly decreased (28 and 11%, respectively), as was LDL cholesterol (33%) after 6 months. High-density lipoprotein cholesterol increased by 24% after 6 months of treatment, and triglycerides rose significantly in the year of therapy (37%).

CONCLUSION

These findings suggest that surgical menopause induces atherogenic changes in the lipid profile in 3 months and that ERT soon reverses them.

Gonadotrophins and prolactin rise after bilateral oophorectomy for benign conditions

The aim of this study was to analyse the changes in follicle stimulating hormone (FSH), luteinizing hormone (LH) and prolactin concentrations in the 3 months following oophorectomy in pre-menopausal women operated on for benign gynaecological conditions. Included in this analysis were 21 women (mean age 47 years, range 46-52) who underwent bilateral oophorectomy plus hysterectomy for fibroids or ovarian cysts. Plasma concentrations of FSH, LH and prolactin were measured before and on days 2, 4, 6, 14 and 30 after surgery; in 10 cases measurements were made on day 60, and in five cases on day 90 after surgery. Hormone concentrations were measured in duplicate daily samples, and immunoenzymatic assay kits were used for all the immunoassays. The FSH and LH concentrations increased constantly after surgery. Mean prolactin concentrations also increased from 12.1 ng/ml before surgery to 31.5 ng/ml on day 14 after bilateral oophorectomy, but decreased thereafter to 18.2 ng/ml on day 30, 10.9 ng/ml on day 60 and 6 ng/ml on day 90. In conclusion, transient (2-3 weeks) increased prolactin concentrations are observed after surgical castration.

Inhibition of neutrophil oxidative metabolism by trichinellosis patient sera. Parasite origin or host induction?

The presence of sera factors able to inhibit both neutrophil chemotaxis and phagocytosis was observed in all patients studied at two months from infection caused by Trichinella britovi and in most of them after one year. Human neutrophils with eosinophils are able to kill T. spiralis newborn larvae in an ADCC system and their major cytotoxic mechanism is oxidative metabolism products. We evaluated the effect of trichinellosis sera on neutrophil oxidative burst to determine if neutrophils are affected by circulating factors during infection. Cells were incubated with sera from trichinellosis patients. Basal or stimulated Superoxide Anion (SA) production and chemiluminescence in response to different stimulation (PMA, f-MLP, opsonized yeasts) of neutrophils incubated with trichinellosis sera were evaluated and compared with those of cells incubated with control sera. The results show that basal SA production was inhibited by 66% of sera and stimulated by 11%. On the contrary f-MLP stimulated production was significantly increased by 22% sera, and inhibited by none. Chemiluminescence in response to f-MLP or PMA was inhibited by 46 and 80% of sera, respectively. These results show that trichinellosis sera can modulate not only SA production but also other steps of the oxidative burst, irrespective of the stimulating agent, so suggesting that different neutrophil activation pathways are affected. Increased IL-2 levels observed in most of the sera did not correlate with the inhibiting capacity of sera. The hypothesis of a parasite origin of the inhibiting factors is discussed in the light of host-parasite relationship.

Sustained prolactin release associated with precocious ovarian failure

Five women after precocious menopause and 1 patient with primary ovarian failure showed a simultaneous elevation of plasma gonadotropin and prolactin. The hypersecretion of plasma prolactin was still present 6 months after ovarian failure. After 12-18 months of observation while FSH and LH concentration remained elevated, prolactin concentrations normalized in 5 women and decreased in 1.