High rate of failure in treatment of imported schistosomiasis

Chronic schistosomiasis imported in France: A retrospective multicentre analysis of 532 patients, calling for international recommendations

BACKGROUND

Schistosomiasis is a major public health issue for migrants. This study aims to describe the clinical presentation and management of imported schistosomiasis in France.

METHODS

We included all new cases of schistosomiasis in patients aged ≥18 years, defined by a positive specific Western blot and/or a positive parasitological analysis of urine, stool or biopsy, between January 1, 2016, and December 31, 2019, in 4 laboratories in Paris and Western France.

RESULTS

Over the study period, 532 patients were included. Mean age was 37 years (18-91), and 461/532 (87 %) were men. Among 476/532 (89 %) patients born in an endemic area, 433 (91 %) were born in sub-Saharan Africa. Most of the patients (405/532, 76 %) had only a positive serology, and 127/532 (24 %) had ova on microscopic examination. Among 361/532 (68 %) who had at least one urine, stool or biopsy analysis, microscopic analysis was positive in 127 (35 %). Imaging showed lesions compatible with schistosomiasis in 88/164 (54 %) patients with clinical symptoms and 13/29 (45 %) patients without (p = 0.5). Patients who arrived in France less than one year before diagnosis were more likely to have clinical symptoms than those who arrived in France 1-5 years and >5 years prior to diagnosis (52 %, 41 % and 43 %, respectively, p = 0.03). Two-hundred and seventeen patients (40.8 %) were left untreated.

CONCLUSION

Approximately 50 % of patients with imported chronic schistosomiasis have radiological abnormalities, whether they are symptomatic or not, and management is heterogeneous. Multidisciplinary international guidelines are requested to clarify the management of this neglected disease.

Prospective cohort study using ultrasonography of Schistosoma haematobium-infected migrants

BACKGROUND

Chronic infection with Schistosoma haematobium may lead to serious complications, including bladder carcinoma. Although it is recommended that only bladder masses not regressing within 6 months after praziquantel intake should be investigated invasively, cystoendoscopy is still often performed at diagnosis even in the absence of further signs of concern. No prospective study so far evaluated the evolution of bladder lesions after treatment in case of no risk of reinfection, which could inform case management.

METHODS

Adult African migrants with active S. haematobium infection, as assessed by positive urine PCR or microscopy for eggs in urine or bladder biopsy, underwent urinary tract ultrasound at enrolment and at 1, 3, 6, 12 and 24 months after praziquantel treatment. Patients in advanced pregnancy or with known Schistosoma-unrelated chronic pathology of the urinary tract were excluded.

RESULTS

Twenty-one patients, aged 18-29 years, participated in the study; ten (47.6%) had bladder masses on ultrasound. Follow-up ≥6 months was completed by 16 (76.2%) patients; ≥12 months by 14 (66.7%) and 24 months by 11 (52.4%). All patients with bladder lesions on enrolment completed a follow-up of ≥6 months. Lesions resolved completely by 6 months in all cases and no new development/re-appearance was observed.

CONCLUSIONS

This is the first prospective, long-term follow-up study with ultrasound of patients with urinary schistosomiasis outside endemic areas. Mucosal masses in young patients regressed after treatment without recurrence, supporting the recommendation that invasive procedures should be avoided unless lesions or other symptoms/signs of concern persist for > 6 months. Further studies should assess the evolution of bladder lesions after treatment in larger populations, including older age groups, and, ideally, with parallel assessment of other biomarkers of urinary pathology and of residual S. haematobium active infection.

Evaluation of microscopy, serology, circulating anodic antigen (CAA), and eosinophil counts for the follow-up of migrants with chronic schistosomiasis: a prospective cohort study

Background

An accurate test for the diagnosis and post-treatment follow-up of patients with schistosomiasis is needed. We assessed the performance of different laboratory parameters, including the up-converting reporter particle technology lateral flow assay to detect circulating anodic antigen (UCP-LF CAA), for the post-treatment follow-up of schistosomiasis in migrants attending a dedicated outpatient clinic in a non-endemic country.

Methods

Routine anti-Schistosoma serology results and eosinophil counts were obtained of patients with positive urine/stool microscopy and/or PCR (confirmed cases) or only positive serology (possible cases), and at least one follow-up visit at 6 (T6) or 12 (T12) months after praziquantel treatment. All sera samples were tested with the UCP-LF CAA assay.

Results

Forty-eight patients were included, 23 confirmed and 25 possible cases. The percentage seropositivity and median antibody titers did not change significantly during follow-up. UCP-LF CAA was positive in 86.9% of confirmed and 20% of possible cases. The percentage positivity and median CAA levels decreased significantly post-treatment, with only two patients having positive CAA levels at T12.

Conclusions

The UCP-LF CAA assay proved useful for the diagnosis of active infection with Schistosoma spp. and highly valuable for post-treatment monitoring in migrants, encouraging the development of a commercial test.

Antigen-based diagnosis of Schistosoma infection in travellers: a prospective study

BACKGROUND

Travellers infected with Schistosoma spp. might be pauci- or even asymptomatic on first presentation. Therefore, schistosomiasis may remain undiagnosed in this population. Active infection, as evidenced by the presence of the tissue-dwelling worm, can be demonstrated via the detection of adult worm-derived circulating anodic antigen (CAA) utilising a robust well-described lateral flow-(LF) based test applying background-free up-converting reporter particles (UCP). In this prospective study, we assessed the diagnostic value of serum and urine UCP-LF CAA test in comparison with two Schistosoma-specific serological assays detecting antibodies against adult worm antigen-immuno fluorescence assay (AWA-IFA) and against soluble egg antigen-enzyme-linked immunosorbent assay (SEA-ELISA) antigens in travellers.

METHODS

Samples were collected from 106 Dutch travellers who reported freshwater contact in sub-Saharan Africa and who were recruited up to 2 years after return. Subjects were asked to complete a detailed questionnaire on travel history, water contact, signs and symptoms compatible with schistosomiasis.

RESULTS

Two travellers were positive by serum CAA and an additional one by urine CAA. A total of 22/106 (21%) samples were antibody positive by AWA-IFA and 9/106 (9%) by SEA-ELISA. At follow-up 6 weeks and 6 months after praziquantel treatment, all seropositives remained antibody positive whereas CAA was cleared. Seropositivity could not be predicted by the type of fresh water-related activity, country visited or symptoms reported.

CONCLUSION

The low number of UCP-LF CAA positives suggests that in travellers, active infections often do not establish or have very low worm burden. Based on our high seroconversion rates, we conclude that the AWA-IFA assay is the most sensitive test to detect schistosome exposure. Given the lack of predictive symptoms or risk factors, we recommend schistosomiasis screening at least by serology in all travellers with reported freshwater contact in high-endemic areas.

Parasitic infections in travelers and immigrants: part II helminths and ectoparasites

Travel and migration contribute to the emergence of certain parasites which may be imported into nonendemic areas. Noncontrolled importation of food products and animals may also contribute to the diagnosis of infections caused by helminths in nonendemic countries. Some helminth infections such as strongyloidiasis may be life-threatening, especially in immunocompromised patients, and outcome depends on correct diagnosis and treatment. Other helminth infections are neglected tropical diseases associated with chronic disease and/or disability. Major challenges concern the development of improved diagnostic techniques, safer and more effective drug therapies and identification of markers of response to treatment. The study of these imported infections in travelers and immigrants may provide opportunities for research which may not be readily available in resource-poor endemic countries. Updated reviews and guidelines are necessary as new data become available. The second part of this review focuses on infections in travelers and immigrants caused by helminths and ectoparasites.

Schistosoma haematobium infection in workers returning from Africa to China

Schistosoma haematobium infection is mainly associated with urinary schistosomiasis. Here, we describe two cases of S haematobium infection in workers returning to China from Tanzania and Angola. They had hematuria and were misdiagnosed as having tuberculosis or tumor of the bladder. The diagnosis was established by discovery of eggs in the urine.

Schistosomiasis: current epidemiology and management in travelers

Schistosomiasis is increasingly encountered among travelers returning from the tropics, mainly from Africa. Schistosoma-infected travelers have served as sentinels for the existence of unknown foci of transmission even outside Africa. Acute schistosomiasis (also termed Katayama syndrome) is the common manifestation among travelers and may follow exposure to any of the Schistosoma species. Neuroschistosomiasis is a rare complication but may result in severe disability. Diagnosis in travelers is hampered by the poor sensitivity of microscopy in urine and stool, especially during acute infections, while seroconversion may be delayed for a period of weeks. During acute schistosomiasis, symptomatic treatment is the only available therapy, while for chronic schistosomiasis, praziquantel is the only drug available, despite reports of emerging resistance to it. Since the potential for exposure to Schistosoma through travel will probably continue to increase, it is clear that new, sensitive diagnostic methods and drugs affecting the parasite in all its stages are needed.

Schistosomiasis: from drug deployment to drug development

PURPOSE OF REVIEW

Schistosomiasis is a chronic and morbid disease that affects hundreds of millions of the poorest individuals in (sub)tropical regions, particularly sub-Saharan Africa. Just one drug, praziquantel (PZQ), is available. As discussed, efforts to expand mass drug administration programs may accelerate the emergence of resistance. In addition, PZQ's peculiar pharmacological profile and undefined mechanism of action(s) complicate discriminating incomplete efficacy from true resistance. Accordingly, and in spite of the challenges associated with developing new antischistosomals as discussed herein, alternatives to PZQ should be identified. Various strategies to do this are highlighted here.

RECENT FINDINGS

The last 2 years have witnessed more engagement of the necessary infrastructure combined with the application of the latest strategies and technologies to facilitate antischistosomal drug discovery. Preclinical and clinical evaluation of new chemistries has benefited from various consortia and institutions that underwrite drug development for antiparasitics in general. Drug repositioning, target-based drug design, improved automation for compound screening, genomics and functional genomics are just some of the tools now being applied to identify possible new drugs and drug targets.

SUMMARY

The new momentum toward the discovery of alternatives to PZQ is encouraging but needs to be sustained by a stronger advocacy for drug development, in addition to drug deployment.

Exotic imported travel-related infections in Japan

Human social and economic activities as well as changes in the global environment are responsible for outbreaks of emerging and re-emerging infectious diseases. We have encountered 5 cases of asymptomatic schistosomiasis in Japanese travelers who were exposed to cercariae-contaminated freshwater in east Africa. Because all 5 travelers showed normal results upon their return medical examination, Schistosoma, which is not indigenous to Japan, was unfortunately not suspected as the causative agent of this chronic and silent infection. In addition, in 2008, we experienced 2 Japanese cases in an exotic and local pandemic of human trichinellosis which was associated with eating raw soft-shelled turtles in Taiwan. The cause of this emerging pandemic can be attributed to the traditional custom of eating raw soft-shelled turtles. It is important for all travelers to understand that anyone at anytime can be exposed to the threat of a pandemic; therefore, the first step for all travelers is to be aware of worldwide endemicity and keep up to date on the infectious diseases that are prevalent. Concurrently, it is important to identify the presence of slowly and silently expanding infectious diseases and establish surveillance systems to detect not only serious emerging infectious diseases but also chronic and silent infections.