An epidemiological and ecological study of human alveolar echinococcosis transmission in south Gansu, China

Human alveolar echinococcosis (AE) is usually a rare, highly pathogenic zoonotic disease, transmitted across the northern hemisphere between fox and rodent hosts. In China the first cases were described in 1965; however very few epidemiological studies have been undertaken since. Following identification in 1991 of a serious focus of human AE in south Gansu province, detailed village-based community and ecological studies were carried out between 1994 and 1997. Hepatic ultrasound mass screening with serological testing (five tests) identified 84/2482 new AE cases (3%). An overall prevalence of 4.1% (135/3331) was recorded for the area when previous cases were also included. Based on a seropositive result only, without an ultrasound scan indication, no additional AE cases were identified. Of the evolutive AE cases, 96% were seropositive in at least one test, while up 15-20% of individuals who exhibited hepatic calcified lesions and 12-15% exhibiting hepatic nodular lesions were seropositive for specific Em2 or Em18 antibodies. Village (n=31) human AE prevalence rates varied from 0 to 15.8%. Questionnaire analysis indicated that total number of dogs owned over a period was a risk factor (P<0.006), but not a history of red fox hunting (P>0.6). Rodent ecology studies revealed an association between density indices of voles (Microtus limnophilus) and village AE prevalence rates, on the one hand, and village landscape characterised by a ratio of scrub/grassland to total area above 50% (P<0.005). Long-term transmission of Echinococcus multilocularis and risk of zoonotic infection of south Gansu farmers may be related ultimately to a process of deforestation driven by agriculture. This in turn probably results in creation of optimal peri-domestic habitats for rodents that serve as intermediate host species (such as M. limnophilus) and subsequent development of a peri-domestic cycle involving dogs.

Epidemiology of alveolar echinococcosis in Xinjiang Uygur autonomous region, China: a preliminary analysis

The Xinjiang Uygur autonomous region (XUAR) in north-western China is known to be endemic for Echinococcosis multilocularis, the causative agent of human alveolar echinococcosis (HAE). Despite regular reports of HAE cases in their region, very little is known about the local epidemiology of the disease or the transmission of E. multilocularis. The epidemiology of HAE in Xinjiang has now been investigated by the analysis of data collected from the medical records of 157 clinical cases who had attended the four main hospitals in the region. These data indicate that the disease is relatively common in the Altai, western Junggar, and Tianshan mountain ranges, whereas the Tarim and Junggar basins are likely to be of low endemicity. The prevalence of the disease in the Kunlun mountains is not clear. Semi-nomadic groups, especially those of Kazakh or Mongol origin, have a higher risk of infection than other ethnic groups. Prevalence of the disease in humans appears to be correlated with aspects of the local climate, such as annual precipitation and temperature. Red foxes, Microtinae, Ochotona spp. and Marmota spp. may be important hosts of E. multilocularis in the XUAR, sustaining the transmission cycles of the parasite.

Immunodiagnosis of Echinococcus infections: confirmatory testing and species differentiation by a new commercial Western Blot

The Echinococcus Western Blot IgG (LDBIO Diagnostics, Lyon, France), using a whole larval antigen from Echinococcus multilocularis, was evaluated for serodiagnosis and differentiation between two human parasitic infections of worldwide importance: cystic echinococcosis, due to Echinococcus granulosus, and alveolar echinococcosis, due to E. multilocularis. Fifty and 61 serum samples from patients with cystic and alveolar echinococcosis, respectively, were used for assessing diagnostic sensitivity. The sensitivity of the assay was compared with those of screening tests used for these applications. Sera used for assessing cross-reactivities were from 154 patients with other diseases, either parasitic or not. The assay allowed the detection of serum immunoglobulin G antibodies in 97% of Echinococcus-infected patients. It had a higher sensitivity than screening assays for the detection for each echinococcosis. The assay allowed us to correctly distinguish between E. granulosus- and E. multilocularis-infected patients in 76% of cases. It did not allow us to distinguish active from inactive forms of both echinococcoses. The occurrence of cross-reactivities with neurocysticercosis indicates the necessity for retesting sera with species-specific antigens, for rare patients with neurologic disorders. This study shows the usefulness of the commercially available Echinococcus Western Blot IgG for the serological confirmation of human echinococcosis.

Resistance/susceptibility to Echinococcus multilocularis infection and cytokine profile in humans. II. Influence of the HLA B8, DR3, DQ2 haplotype

Differences have been shown between HLA characteristics of patients with different courses of alveolar echinococcosis (AE). Notably the HLA B8, DR3, DQ2 haplotype was associated with more severe forms of this granulomatous parasitic disease. We compared IL-10, IL-5, interferon-gamma (IFN-gamma) and tumour necrosis factor (TNF) secretion by peripheral blood mononuclear cells (PBMC) isolated from eight HLA-DR3+, DQ2+, B8+ AE patients and from 10 HLA-DR3-, DQ2-, B8- patients after non-specific mitogenic and specific Echinococcus multilocularis antigenic in vitro stimulation. PBMC from seven HLA-DR3+, DQ2+, B8+ healthy subjects and nine HLA-DR3-, DQ2-, B8- subjects were also studied as controls. PBMC from AE patients with HLA DR3+, DQ2+ haplotype secreted higher levels of IL-10 without any stimulation and after specific antigenic stimulation than did patients without this haplotype. Higher levels of IL-5 and IFN-gamma were also produced by these patients' PBMC after stimulation with non-purified parasitic antigenic preparations; however, the specific alkaline phosphatase antigen extracted from E. multilocularis induced only Th2-type cytokine secretion. A spontaneous secretion of TNF by HLA DR3+, DQ2+ B8+ AE patients was also found. These results suggest that HLA characteristics of the host can influence immune-mediated mechanisms, and thus the course of AE in humans; specific antigenic components of E. multilocularis could contribute to the preferential Th2-type cytokine production favoured by the genetic background of the host.

Resistance/susceptibility to Echinococcus multilocularis infection and cytokine profile in humans. I. Comparison of patients with progressive and abortive lesions

To clarify the role of Th1- and Th2-type cytokines in the various outcomes of human alveolar echinococcosis (AE), the cytokine immune response of self-cured patients was studied and compared with those of progressive AE patients and healthy subjects. Self-cured patients were divided into two groups according to the following clinical features: subjects who had positive Echinococcus multilocularis serologies and hepatic calcifications typical of AE were classified as 'abortive AE' patients, and those who had positive E. multilocularis serologies but no hepatic lesions or calcifications detectable by ultrasonography were classified as 'positive serology' subjects. Secretions of IL-5, IL-10 and interferon-gamma, and expression of IL-5 mRNA were evaluated in peripheral blood mononuclear cells (PBMC) stimulated in vitro with the mitogen phytohaemagglutinin-C or specific E. multilocularis antigenic preparations. The cytokine profile of abortive AE patients was the opposite of that observed in progressive AE patients. An intermediate profile was observed in positive serology subjects. PBMC from abortive AE patients, whether non-stimulated or stimulated with PHA and antigenic preparations, secreted significantly lower levels of IL-10 than those isolated from progressive AE patients. Our observations seem to confirm the regulatory role of IL-10 in the immunopathology of human AE.

Effect of an auditory stress on peritoneal and alveolar cells in C57 BL/6J mice of advanced age

The aim of this study was to analyse the effects of auditory stress on peritoneal and alveolar macrophages in C57 BL/6J mice of advanced age, and to compare the results to those obtained in old mice submitted to a sham stress, and to those observed in young mice submitted to the same auditory stress. We used a chemiluminescence assay to measure the production of free oxygen radicals (FOR) by macrophages. Eight 22 month-old mice were exposed to a sound stress of 110 dB for three consecutive nights; nine were submitted to a sham stress. The results were compared to those obtained in young (8 week-old) mice, 21 submitted to noise stress, and 17 controls. The corticosterone level was not increased after stress in any group. FOR production in old mice was significantly higher than that in young mice. Stress did not induce significant changes in FOR production by alveolar cells in young mice; however, the FOR production by alveolar cells was significantly higher in the stressed group than in the control group of old mice. These results show that noise stress is associated with modifications of macrophage functions that are influenced by cell localization, the behaviour of alveolar and peritoneal macrophages of old mice being clearly different in our experimental model.

A twenty-year history of alveolar echinococcosis: analysis of a series of 117 patients from eastern France

OBJECTIVES

Alveolar echinococcosis of the liver is a very rare and severe parasitic disease due to the growth of the larva of Echinococcus multilocularis. The aim of this paper was to describe a 20-year study of the epidemiological, clinical and therapeutic aspects of alveolar echinococcosis in eastern France.

DESIGN

One hundred and seventeen consecutive cases, diagnosed and followed in our liver unit, were studied from 1972 to 1993.

METHODS

Data from 85 patients followed since 1983 (period B) were compared to data from a first series of 32 patients (period A) collected from 1972 to 1982; 1983 was chosen as the cut-off year because of the numerous changes that occurred in the diagnosis, follow-up and treatment of the disease at this time, in particular the introduction of parasitostatic benzimidazoles.

RESULTS

The results of patient follow-up were evaluated in December 1997. The cumulative prevalence was 2.5 per 100,000 persons in period A whereas it reached 6.6 per 100,000 in period B. The annual incidence in period B was 7.3 on average, compared with 2.7 in period A. Twenty-nine per cent of patients from period B were asymptomatic at the time of diagnosis compared with 10% in period A. This change was correlated with less advanced liver lesions, and was related to the extensive use of abdominal ultrasound, and from 1987, serological screening. Curative resections were performed in 24% of the cases in period B versus only 3% in period A. From 1986, liver transplantations were performed in eight patients from period A and 13 patients from period B. In period B, palliative surgery was frequently replaced by radiological non-operative procedures to treat abscesses and jaundice. From 1982, 73 patients received benzimidazoles for a period of time ranging from 4 to 138 months. Stabilization of the lesions was observed in two-thirds of the patients. Episodes of jaundice or digestive haemorrhage due to portal hypertension were 31.5 and 11 times less frequent respectively in patients from period B compared with period A. Actuarial survival at 5 years improved from 67% in period A to 88% in period B in patients of similar age.

CONCLUSIONS

Radical changes in the diagnosis and the management of alveolar echinococcosis have occurred during the last decade. Together they have contributed to an improvement in the status of the patients affected by this very severe parasitic disease.

[Psychoimmunology: a questionable model?]

INTRODUCTION

The concept of "psychoimmunology" that had long been supported by clinical observation and common sense, has acquired a sound scientific basis in the last two decades. The discovery of neuro-mediators and cytokines and their receptors shared by the central nervous system and the immune system has prompted research work using reliable methodologies to study the relationship between a 'hard' scientific field, such as immunology, and a 'soft' one, such as the behavioral sciences.

CURRENT KNOWLEDGE AND KEY POINTS

The complexity of the studies on stress and immunity lies upon the choice of immunological measurements and the development of reproducible stress protocols. Models of stress in experimental animals may address acute versus chronic stress, and individual versus social stress. In humans, typical situations such as academic exams, and care given to patients with dementia, for instance, have been chosen to study large groups of subjects. The development of self-questionnaires for a reliable evaluation of stress and its consequences has led to more accurate measurements of psychosocial events. In animals, acute stress usually drives the immune response towards a Th2, grossly 'immunosuppressive,' profile. In humans, acute stress associates an endocrine response (characterized by glucocorticoid secretion and hyperprolectinemia) with an immunosuppression. Chronic stress is more likely to induce a range of effects, depending on the capacity of the subject to cope with stress, and on his/her social environment. Among the numerous mediators of the hypothalamo-pituitary cascade, Corticotropin Releasing Hormone is a key factor in the stress-immunity relationship. Several studies in humans have demonstrated the influence of stress on the susceptibility to infections (including HIV infection) and on survival in malignant diseases. In autoimmune diseases, a high prevalence of depression, as well as a particular sensitivity to stressful events, seem to modify the course of conditions such as systemic lupus erythematosus, rhumatoid arthritis or Sjögren's disease. The relationship between stress and diseases is based on the pathogenic model which involves the following chain of events: stressor, reaction to stress, neuro-endocrine changes, abnormalities of the immune response, and occurrence (or aggravation) of a disease. The evolution from health to disease could be associated, at least partially, with a 'passive' immunosuppressive mode of response, mediated by the pituitary-adrenal axis, typically the opposite of an 'active,' immunostimulant mode of response, mediated by adrenergic stimulation.

FUTURE PROSPECTS AND PROJECTS

Concept-related problems still remain to be solved: adaptation to stress ('coping'), is both genetically and socially mediated; the significance and interpretation of stress-related abnormalities and their precise involvement in the pathogenesis of diseases may be ambiguous. However, available epidemiological and pathophysiological evidence is currently sufficient to allow physicians in their everyday practice to take stress and depression into account in order to markedly improve the prognosis of many diseases related to immune responses. Prospective studies of neuropsychological intervention, using either pharmacologic or behavioral approaches, should be made to provide the necessary rational to a psychoimmunological management of patients.

Primary disease recurrence after liver transplantation for alveolar echinococcosis: long-term evaluation in 15 patients

Between 1986 and 1991, 21 patients received liver grafts in our center for incurable alveolar echinococcosis (AE). The aim of this study was to analyze the long-term results in 15 of these 21 patients who survived more than 1 year after undergoing a liver transplantation (LT). The follow-up, mainly aimed at the diagnosis of recurrence, consisted of repeated radiological and specific immunological investigations. The role of pre- and post-LT benzimidazole (BZM) therapy was also evaluated. Among the 15 patients, 8 patients had a palliative LT related to previously known pulmonary AE metastases and/or inextirpable abdominal parasitic foci. In the 7 remaining patients, LT was considered curative. In June 1998, the mean follow-up duration was 96 months (range: 28-138 months). Five late deaths occurred, 2 of them were directly related to residual AE. A reinfection of the graft was observed in 4 patients. Preoperative BZM therapy seemed useful in preventing or delaying the parasitic recurrence. Post-LT BZM was able to stabilize and even to reduce residual AE. The anti-Em2 enzyme-linked immunosorbent assay (ELISA), which is the standard test used in patient follow-up after partial liver resection for AE, did not appear useful in detecting recurrence here; however, an ELISA, using a crude heterologous antigen (Echinococcus granulosus) allowed early diagnosis of residual AE. In conclusion, primary disease recurrence is not rare after LT for AE. Immunosuppressive therapy may favor larval growth in extrahepatic sites; therefore, an extensive extrahepatic radiological check-up has to be performed before LT. BZM therapy seems to stabilize residual foci. Anti-Eg immunoglobulin G (IgG) follow-up is the most useful test for early diagnosis of parasite recurrence.

[Treatment of recurrent ulceration with low doses of thalidomide. Pilot study in 17 patients]

PURPOSE

Though thalidomide in a dosage of 100 mg/day is the standard treatment for recurrent oral and genital ulcers (OGU), its toxicity would be less important with lower dosage, while its efficacy would be identical. Furthermore, duration of treatment might be a major risk factor for the development of subsequent polyneuropathy. To determine the dosage of thalidomide leading to the best efficacy/toxicity ratio, a pilot study was conducted from 1993 to 1996.

METHODS

Seventeen patients with OGU (mean age: 43 years, sex-ratio: 12:5) were included in the study and presented either recurrent oral ulcerations (8 patients), oro-genital ulcerations (3 patients), Behçet disease (4 patients), or recurrent OGU associated with leukemia (2 patients). The initial dosage of thalidomide was 50 mg/day (1 tablet) for 1 month. If the patient's condition improved, the dosage was reduced to one tablet every other day for 1 month and one tablet every 3 days thereafter. Nerve conduction studies (EMG) were performed at inclusion in the study and every 6 months thereafter.

RESULTS

Among the 17 patients, remission was observed in ten patients within the first month of treatment and the condition of seven patients improved. Complete remission was observed in six patients after a 2-month treatment and in one patient after 4 months. A 200-mg/8 days dosage induced prolonged remission in 12 patients. Among them, ten patients received a 150-mg dosage over 8 days thereafter and disease relapsed in four of them. Among the six patients who received a 100-mg dosage over 8 days, only one relapse was observed. EMG showed a decrease in sensory nerve action potentials in six patients after 8 months and a half on average. Only three patients had to discontinue their treatment due to the occurrence of either paresthesia (2 patients) or areflexia (1 patient). Our study shows that initially a 50-mg/day dose is efficacious in the treatment of OGU and that administration of one tablet every 2 or 3 days is efficacious in more than 60% of the patients to maintain remission.

CONCLUSION

A dosage of 50 mg/day is initially efficacious in most cases, provided that the patient is carefully followed up to allow early detection of potential peripheral neuropathy.

Highly active antiretroviral therapy (HAART) for the treatment of infection with human immunodeficiency virus type 1

Highly active antiretroviral therapy (HAART) refers to a broad category of treatment regimens usually comprised of three or more antiretroviral drugs that, in previously untreated HIV-1-infected patients, are expected to reduce plasma virus levels below the limits of detection. Most HAART regimens include drugs from at least two of the three classes of antiretroviral therapy (nucleoside analog reverse transcriptase (RT) inhibitors, non-nucleoside analog RT inhibitors, and protease inhibitors). In deciding when to initiate antiretroviral therapy, physicians and their patients must balance the virological and immunological benefits of early treatment with the costs of drug therapy, the risk of drug side effects, and the risk of drug resistance if adherence is suboptimal. In previously untreated patients, HIV-1 replication can be suppressed indefinitely with certain HAART regimens. In previously treated patients, the benefits of HAART are often significantly diminished.

Intestinal and systemic humoral immunological events in the susceptible Balb/C mouse strain after oral administration of Echinococcus multilocularis eggs

The aim of the study was to investigate the systemic and, for the first time, the intestinal humoral events in the susceptible Balb/C mouse strain after oral administration of Echinococcus multilocularis eggs. Thirty-one mice were divided into three groups; W-2, W-8 and control group. Each mouse of the W-2 and W-8 groups was orally infected with 1,500 E. multilocularis eggs, two weeks and eight weeks before sacrifice respectively. Control group mice received phosphate buffer saline. Measurement of anti-E. multilocularis and non-specific IgG, IgA and IgM, and of a transudation marker, albumin, were performed in serum and intestinal washings by a time-resolved immunofluorometric assay. These results were complemented by microscopic examination of the intestinal mucosa. This infection model is well-suited to the study of mucosal immunity during alveolar echinococcosis. It showed a major specific intestinal response in the early stage of the disease whereas the systemic response predominated later in the disease. Histopathological studies and calculation of the relative coefficient of excretion of Ig also confirmed that the presence of the parasite, even during a short period, was responsible for a local immunological and inflammatory response and for a change in mucosal permeability. Mucosal immunity could thus play a role in tolerance induction against E. multilocularis that could be a prerequisite for the subsequent development of the larvae in the liver, and for the occurrence of the parasitic disease, alveolar echinococcosis.

Echinococcus multilocularis infection in mice: in vivo treatment with a low dose of IFN-gamma decreases metacestode growth and liver fibrogenesis

As no antiparasitic drug is definitively efficient in patients with alveolar echinococcosis, the effects of exogenous IFN-gamma on murine Echinococcus multilocularis infection were assessed with regards to the parasite burden, parasite-specific immune responses, and the urinary level of the collagen cross-link pyridinolines. They were analyzed after 3-week treatments with 1 or 5 micrograms of IFN-gamma per day twice a week. The treatment with 1 microgram transiently reduced the liver metacestode load, and the metastase weight as far as 6 weeks after the end of treatment. It slightly increased Th 1-type T cell responses and reduced the excretion of pyridinolines. These results should encourage further study to assess whether the decrease in liver fibrosis leads to an improvement of the efficacy of albendazole therapy. In contrast, the treatment with 5 micrograms increased the liver metacestode load and was less efficient than that with 1 microgram in decreasing pyridinoline excretion. These results incitate to follow up carefully patients with alveolar echinococcosis who are treated with IFN-gamma.

The level of the collagen cross-link pyridinoline reflects the improvement of cutaneous lesions in one case of skin alveolar echinococcosis

Cutaneous parasitic lesions, associated with a dense fibrous reaction, markedly improved under albendazole treatment in one case of supraumbilical skin localization of alveolar echinococcosis. Since collagen cross-linking increases during fibrogenesis and contributes to the stability of fibrotic lesions, we monitored the level of the cross-links pyridinoline and pentosidine in skin lesions from this patient to determine if they would reflect the changes occurring during treatment. We looked at the deposition of cross-linked type I collagen by immunohistochemistry and also measured the serum concentrations of pentosidine and of a fragment of type I collagen (ICTP), which contains a site of pyridinoline formation. Albendazole treatment did not affect either the collagen content of skin lesions or the serum concentrations of ICTP and pentosidine, but it led to a pronounced decrease in pyridinoline level concomitant with the disappearance, observed by immunohistochemistry, of extensively cross-linked fibrotic type I collagen. The follow-up of collagen cross-linking by pyridinoline in skin tissue thus appears to be useful in reflecting the improvement of fibrotic skin diseases during therapy.

HLA and alveolar echinococcosis

Evidence in animal intermediate hosts that susceptibility to larval infection with Echinococcus multilocularis is restricted to individual host factors prompted us to investigate the susceptibility markers in humans. Because antigens of the extracellular parasite E. multilocularis are possibly presented by MHC molecules in a restricted way, we speculated that MHC polymorphism may influence resistance of the host towards infection and course of disease. We studied HLA-A, -B, -DRB1, -DQB1 and -DPB1 polymorphism in 151 patients with alveolar echinococcosis. Patients with an observation period of more than 2 years were grouped according to the clinical follow-up into cured (no recurrence following surgery) patients and patients with regressive or progressive forms of disease during benzimidazole chemotherapy. By comparing phenotypic frequency between patients with alveolar echinococcosis and healthy controls, HLA-DRB1*11 was associated with a reduced risk for disease development (odds ratio=0.55, 95% confidence interval=0.34-0.88; P=0.01). HLA-DQB1*02 was more frequent in patients with progressive disease when compared with patients with regressive disease (54.3% vs 28.3%, P=0.02). The result suggests that HLA-DRB1*11 might confer protection against alveolar echinococcosis and that HLA-DQB1*02 may indicate a risk for progressive disease development. The findings may facilitate the search for immunodominant T-cell epitopes of E. multilocularis.

Echinococcus multilocularis: relationship between susceptibility/resistance and liver fibrogenesis in experimental mice

To analyze collagen and other matrix protein deposits in experimental alveolar echinococcosis as well as the expression of lysyl oxidase, the enzyme that initiates the first steps in the pyridinoline cross-linking of collagen, and to establish a relationship between resistance/susceptibility to Echinococcus multilocularis larval growth and fibrogenesis, we compared AKR/J mice (susceptible to E. multilocularis infection) with NMRI mice (resistant hosts) in this study. Collagen deposits in the lesions were evaluated using a colorimetric method; the nature of matrix proteins involved in the periparasitic fibrosis and lysyl oxidase expression were assessed using immunostaining on tissue sections. The results obtained in this sequential study confirm that fibrogenesis is an important aspect of the host immune reaction against parasitic development and that both the extent and the course of matrix protein deposition differ in the liver of susceptible and resistant mice, respectively. The long-lasting expression of alpha-actin and lysyl oxidase by host cells in NMRI mice suggests that in this resistant strain, fibrosis was not only more developed but also more highly cross-linked and, thus, less sensitive to collagenases than in susceptible mice. A very strong expression of lysyl oxidase by parasitic cells was observed in both strains of mice; the observation that E. multilocularis itself has a role in lysyl oxidase cross-linking of host collagens can be hypothesized and would be a new example of parasite-host interplay.