Efficacy of ivermectin for chronic strongyloidiasis: two single doses given 2 weeks apart

We assessed the efficacy and adverse effects of ivermectin for the treatment of chronic strongyloidiasis. Fifty patients were treated with a single dose of ivermectin at approximately 200 μg/kg, and the dose was repeated 2 weeks later. The eradication rate was 96% (48 of 50 patients) at 2 weeks after the first dose and 98% at 2 weeks after the second dose (49 of 50 patients). In the latter cases, no recurrence was noted at the end of the 4-month post-treatment follow-up period. The gastrointestinal symptoms observed most frequently before the treatment were borborygmus, constipation, and diarrhea. These symptoms improved in the majority of patients after the treatment. Side effects, including nausea and vomiting, occurred in 1 patient (2%), but these were mild and transient. Although abnormal values in laboratory tests were observed in 4 patients (8%), they were mild, and no particular clinical care was required. Thus, ivermectin showed an excellent antihelminthic effect, with little toxicity. Our results indicate that a regimen of two single doses of 200 μg/kg ivermectin, given 2 weeks apart, is clinically suitable for the treatment of chronic strongyloidiasis. Received: April 25, 2001 / Accepted: November 16, 2001     

Regulation of immune responses to Strongyloides venezuelensis challenge after primary infection with different larvae doses

Nematode infections are generally followed by high rates of reinfection, leading to elevated prevalence in endemic areas. Therefore, the effective control of nematode infections depends on understanding the induction and regulation of protective mechanisms. However, most experimental models for protective immune response against nematodes use high parasite exposure, not always reflecting what occurs naturally in human populations. In this study, we tested whether infecting mice with different Strongyloides venezuelensis larvae loads would affect protective responses against reinfection. Interestingly, we found that a previous infection with 10–500 larvae conferred high rate of protection against reinfection with S. venezuelensis in mice, by destroying large numbers of migrating larvae. However, low‐dose priming did not abolish adult worm maturation, as detected in high‐dose primed group. Results also indicated that a previous low‐dose infection delayed the development of cellular infiltrate, while a high inoculum rapidly induced these inflammatory features. Cytokine production by splenocyte cultures of challenge infected mice demonstrated that low‐dose priming had increased production of IL‐4 and IFN‐γ, while high‐dose induced IL‐4 production but not IFN‐γ. Our data support the hypothesis that low‐dose nematode infection does not induce a polarized type‐2 immune response, allowing adult worm survival.     

Clinical presentation and diagnostic sensitivity of laboratory tests for Strongyloides stercoralis in travellers compared with immigrants in a non-endemic country

OBJECTIVES: To assess whether the clinical and laboratory methods for diagnosing Strongyloides stercoralis infection in non-endemic countries is different between those who are chronically exposed and those who travel. METHODS: Analysis of laboratory and clinical data from 204 patients having S. stercoralis infection at the Hospital for Tropical Diseases, London. RESULTS: Sixty-four travellers and 128 immigrants from endemic countries had laboratory-proven strongyloides. In those with microscopically proven disease, serology was 73% sensitive in travellers and 98% sensitive in immigrants (P < 0.001). There was no difference in the eosinophil count between the two groups with 19% having a normal count. Patterns of symptoms varied between the groups, and around one-third were asymptomatic in both groups. Serology was of limited use in follow-up. CONCLUSIONS: Eosinophil count and stool microscopy are insufficiently sensitive to be used alone for screening strongyloides. The sensitivity of serology is good in immigrants with chronic infection, but lower in travellers.     

野生树鼩肠道蠕虫感染调查及分析

目的调查野生树鼩(Tupaia belangeri Chinensis)感染肠道蠕虫的主要种类并进行鉴定,为今后树鼩寄生虫检测提供形态学参考,为实验树鼩寄生虫控制提供依据。方法采集203只野外来源的树鼩新鲜粪便,虫卵采用常规粪便直接涂片以及孵化后显微镜观察;绦虫采用压片、固定染色,以及线虫经透明后体视镜观察,虫卵与成虫相对应鉴定。结果野生树鼩肠道蠕虫的总感染率为75.86%,主要感染种类有3种,经鉴定为长膜壳绦虫、奇口线虫和粪类圆线虫,感染率分别为27.67%,30.06%和51.52%。三种蠕虫的混合感染率为4.55%。两种线虫虫卵在树鼩粪便中多为含胚胎形态。结论野生树鼩肠道蠕虫的感染率较高。对野外引入的新种源必须隔离检疫,进行针对性的药物治疗,才能有效地控制肠道寄生虫病的传播。     

Persistent infection of Strongyloides venezuelensis and normal expulsion of Nippostrongylus brasiliensis in Mongolian gerbils, Meriones unguiculatus, with reference to the cellular responses in the intestinal mucosa

The kinetics of daily faecal egg count, worm burdens, and intestinal cellular responses were examined in Mongolian gerbils after infection with either Strongyloides venezuelensis or Nippostrongylus brasiliensis alone, or concurrently with both parasites. The results show that, both in individual and concurrent infections, S. venezuelensis infection persisted for over 10 weeks and elicited a gradual increase in number of mast cells in the jejunal mucosa. On the other hand, N. brasiliensis worms were expelled by 3 weeks in association with goblet cell hyperplasia. These results suggest that effector/regulator cells involved in worm expulsion are different and highly selective depending on the genus of intestinal helminths.     

吸毒者感染粪类圆线虫1例报告

本文报道了吸毒者感染粪类圆线虫1例，用肠虫清按常规治疗，治愈。     

Use of dried blood spots to define antibody response to the Strongyloides stercoralis recombinant antigen NIE

An approach to improve the diagnosis of Strongyloides stercoralis infection is the use of serologic assays utilising the NIE antigen from S. stercoralis, with good diagnostic sensitivity and excellent specificity reported. Detection of antibody eluted from dried blood spots (DBS) has shown utility in large-scale seroepidemiological studies for a range of conditions and is appealing for use with children where sample collection is difficult. We adapted an existing NIE-enzyme linked immunosorbent assay (ELISA) for the testing of strongyloides antibody response on DBS, and evaluated it in a population screening and mass drug administration programme (MDA) for strongyloidiasis conducted in an Australian indigenous community. Study participants were treated with 200 μg/kg ivermectin (>15 kg) or 3× 400 mg albendazole (<15 kg). The sensitivity of the NIE DBS-ELISA was determined by receiver operator characteristic (ROC) analysis to be 85.7%. A total of 214 DBS were collected from 184 participants across two screening and MDA encounters. A total of 27 of 164 participants (16.5%) tested positive for S. stercoralis NIE-DBS prior to MDA treatment, and 6 of 50 participants (12.0%) tested positive after treatment. These prevalence values are similar to those documented by standard serology in the same community. For 30 participants where a DBS was collected at both MDA 1 and 2, a significant decline in ELISA values was evident post treatment (0.12–0.02, p = 0.0012). These results are in agreement with previous studies documenting the high seroprevalence of S. stercoralis in remote Australian Indigenous communities, and suggest that collection of dried blood spots may be a useful approach for field diagnosis of S. stercoralis seroprevalence.     

Flare-up of ulcerative colitis after systemic corticosteroids： A strong case for Strongyloides

Super-imposed infection with intestinal organisms can mimic a flare-up of underlying disease in patients with inflammatory bowel disease （IBD）. We report a case of patient with long standing ulcerative colitis （UC）, who presented with abdominal pain, diarrhea and low- grade fever after receiving systemic corticosteroids for an unrelated disorder. Despite a negative stool examination, a peripheral eosinophilia reappeared upon tapering down of a corticosteroid dose. Subsequently, duodenal biopsies showed evidence for Strongyloides, presumably acquired 20 years ago when the patient was residing in Brazil. The patient fully recovered following anti-helmintic therapy. This case underscores the importance of considering Strongyloides in the work-up of flaring-up IBD patients, even if a history of residing or traveling to endemic areas is in the distant past.     

Pulmonary strongyloidiasis presenting as chronic bronchitis leading to interlobular septal fibrosis and cured by treatment

Two patients presented with long-standing chronic bronchitis and exertional dyspnoea of 5 and 3 months' duration, respectively, and had interlobular septal fibrosis on chest high resolution CT. In the past both had lived in areas in which Strongyloides stercoralis was known to be endemic. Serological tests confirmed the diagnosis of pulmonary strongyloidiasis, and both patients were treated with anti-helminthic medications, including albendazole and ivermectin. Following this there was complete resolution of both symptomatic and radiological manifestations of their disease. An awareness of the possibility of Strongyloides infection presenting with respiratory symptoms in patients exposed to this parasite is important in the management of such patients.