Seroprevalence status of vaccine-preventable diseases in migrants living in shelter centers in Barcelona, Spain.

INTRODUCTION: Almost 281 million people were living in a foreign country in 2022, and more than 100 million were displaced because of war conflicts and human right violations. Vaccination coverage of infectious diseases in migrants from some disadvantaged settings could be lower than reception countries populations, consequently seroprevalence studies and better access to vaccination could contribute to reducing these differences. METHODS: A descriptive retrospective cross-sectional study was conducted including migrants, living ≤5 years in the reception country and ≥16 years old, who requested a medical exam between January 1st, 2020 and January 31st, 2021. Seroprevalence assessment was performed, and vaccination was offered to those individuals without immunity to hepatitis B, hepatitis A, varicella, measles, mumps, and rubella. RESULTS: A total of 315 migrants were attended during the study period. Immunity protection at arrival was 252/296 (85.1%) for measles, 274/295 (92.9%) for rubella, 257/296 (86.8%) for mumps, 264/295 (89.5%) for varicella, 267/313 (85.3%) for hepatitis A, and 104/300 (34.6%) for hepatitis B. The final immunity protection after full vaccination schedules was 278/296 (93.9%) for measles, 287/295 (97.3%) for rubella, 274/296 (92.6%) for mumps, 276/295 (93.6%) for varicella, 280/313 (89.5%) for hepatitis A, and 139/300 (46.3%) for hepatitis B. CONCLUSIONS: The vaccination intervention has increased immunity rates for the studied diseases in the attended migrants in our center, however, such interventions should be maintained to reach local population immunization levels. Moreover, the collaboration between shelter and reference specialized health centers is fundamental to implement such vaccination programs.

Epidemiological and clinical trends of imported strongyloidiasis in a referral international health unit, Barcelona, Spain: A 12-year period experience.

BACKGROUND: Imported strongyloidiasis in non-endemic countries has increasingly been diagnosed. The aim of the present study is to describe the main epidemiological and clinical characteristics of patients with imported strongyloidiasis attended in a referral International Health Unit and to detect trend changes over a 12-year period. METHODS: This is an observational retrospective study including all imported strongyloidiasis cases seen at the International Health Unit Vall d'Hebron-Drassanes (Barcelona, Spain) from January 2009 to December 2020. Epidemiological and clinical characteristics from included patients were collected. RESULTS: Overall, 865 cases of imported strongyloidiasis were diagnosed, of whom 472 (54.6 %) were men and mean age was 38.7 (SD 13.4) years. Most cases were diagnosed in migrants (830, 96 %). The distribution of the geographic origin was: Latin America (561, 67.6 %), Sub-Saharan Africa (148, 17.8 %), Asia (113, 13.6 %), North Africa (5, 0.6 %), Eastern Europe (2, 0.2 %), and North America (1, 0.1 %). The main reasons for consultation at the Unit were screening of health status (371, 42.9 %), laboratory test alteration (367, 42.4 %), gastrointestinal symptoms (56, 6.5 %), cutaneous symptoms (26, 3 %), and other clinical symptoms (45, 5.2 %). An increase in the number of cases was observed in the last years of the study period. CONCLUSIONS: Imported strongyloidiasis has increasingly been diagnosed in our referral unit, mostly due to screening strategies implementation. Most of the patients were young migrants coming from Latin America, with no symptoms at the time of diagnosis. The optimization of screening strategies will increase the detection and treatment of cases, reducing potential complications.

Unexpected Loa loa Finding in an Asymptomatic Patient From The Gambia: A Case Report.

A 17-year-old asymptomatic male from The Gambia presented for a routine health examination after migration to Spain. Laboratory diagnosis confirmed the presence of Loa loa microfilariae. This unusual finding emphasizes the importance of screening in newly arrived migrants and the need of an extended anamnesis including migratory route and previous travels.

Can haematological changes constitute a surrogate diagnostic parameter to detect schistosomiasis in migrants and travellers? - A retrospective analysis.

Background: Earlier studies found characteristic haematological changes in African patients with active schistosomiasis. If consistently present, full blood counts (FBC) may be helpful to diagnose schistosomiasis also in migrants and returning travellers. Methods: A retrospective patient record review was conducted on data from seven European travel clinics, comparing FBC of Schistosoma egg-positive travellers and migrants to reference values. Sub-analyses were performed for children, returned travellers, migrants and different Schistosoma species. Results: Data analysis included 382 subjects (median age 21.0 years [range 2-73]). In returned travellers, decreases in means of haemoglobin particularly in females (ß = -0.82 g/dL, p = 0.005), MCV (ß = -1.6 fL, p = 0.009), basophils, neutrophils, lymphocytes and monocytes (ß = -0.07, p < 0.001; -0.57, p = 0.012; -0.57, p < 0.001 and -0.13 103/µL, p < 0.001, respectively) were observed. As expected, eosinophils were increased (ß = +0.45 103/µL, p < 0.001). In migrants, a similar FBC profile was observed, yet thrombocytes and leukocytes were significantly lower in migrants (ß = -48 103/µL p < 0.001 and ß = -2.35 103/µL, p < 0.001, respectively). Conclusions: Active egg-producing Schistosoma infections are associated with haematological alterations in returned travellers and migrants. However, these differences are discrete and seem to vary among disease stage and Schistosoma species. Therefore, the FBC is unsuitable as a surrogate diagnostic parameter to detect schistosomiasis.

Post-infectious irritable bowel syndrome following a diagnosis of traveller's diarrhoea: a comprehensive characterization of clinical and laboratory parameters.

BACKGROUND: Prolonged or recurrent gastrointestinal symptoms may persist after acute traveller's diarrhoea (TD), even after adequate treatment of the primary cause. This study aims to describe the epidemiological, clinical and microbiological characteristics of patients with post-infectious irritable bowel syndrome (PI-IBS) after returning from tropical or subtropical areas. METHODS: We conducted a retrospective study of patients presenting between 2009 and 2018 at the International Health referral centre in Barcelona with persistent gastrointestinal symptoms following a diagnosis of TD. PI-IBS was defined as the presence of persistent or recurrent gastrointestinal manifestations for at least 6 months after the diagnosis of TD, a negative stool culture for bacterial pathogens and a negative ova and parasite exam after targeted treatment. Epidemiological, clinical and microbiological variables were collected. RESULTS: We identified 669 travellers with a diagnosis of TD. Sixty-eight (10.2%) of these travellers, mean age 33 years and 36 (52.9%) women, developed PI-IBS. The most frequently visited geographical areas were Latin America (29.4%) and the Middle East (17.6%), with a median trip duration of 30 days (IQR 14-96). A microbiological diagnosis of TD was made in 32 of these 68 (47%) patients, 24 (75%) of whom had a parasitic infection, Giardia duodenalis being the most commonly detected parasite (n = 20, 83.3%). The symptoms persisted for a mean of 15 months after diagnosis and treatment of TD. The multivariate analysis revealed that parasitic infections were independent risk factors for PI-IBS (OR 3.0, 95%CI 1.2-7.8). Pre-travel counselling reduced the risk of PI-IBS (OR 0.4, 95%CI 0.2-0.9). CONCLUSIONS: In our cohort, almost 10% of patients with travellers' diarrhoea developed persistent symptoms compatible with PI-IBS. Parasitic infections, mainly giardiasis, seem to be associated with PI-IBS.

Evaluation of Two Different Strategies for Schistosomiasis Screening in High-Risk Groups in a Non-Endemic Setting.

A consensus on the recommended screening algorithms for schistosomiasis in asymptomatic high-risk subjects in non-endemic areas is lacking. The objective of this study was to evaluate the real-life performance of direct microscopy and ELISA serology for schistosomiasis screening in a high-risk population in a non-endemic setting. A retrospective cohort study was conducted in two out-patient Tropical Medicine units in Barcelona (Spain) from 2014 to 2017. Asymptomatic adults arriving from the Sub-Saharan region were included. Schistosomiasis screening was conducted according to clinical practice following a different strategy in each setting: (A) feces and urine direct examination plus S. mansoni serology if non-explained eosinophilia was present and (B) S. mansoni serology plus uroparasitological examination as the second step in case of a positive serology. Demographic, clinical and laboratory features were collected. Schistosomiasis cases, clinical management and a 24 month follow-up were recorded for each group. Four-hundred forty individuals were included. The patients were mainly from West African countries. Fifty schistosomiasis cases were detected (11.5% group A vs. 4 % group B, p = 0.733). When both microscopic and serological techniques were performed, discordant results were recorded in 18.4% (16/88). Schistosomiasis cases were younger (p < 0.001) and presented eosinophilia and elevated IgE (p < 0.001) more frequently. Schistosomiasis is a frequent diagnosis among high-risk populations. Serology achieves a similar performance to direct diagnosis for the screening of schistosomiasis in a high-risk population.

Imported Strongyloides stercoralis infection and diabetes mellitus and other metabolic diseases: Is there any association?

OBJECTIVES: Strongyloidiasis is a nematode infection caused by Strongyloides stercoralis. Previous studies have addressed the possibility of the parasite to establish a complex relationship with the host that could affect the risk of developing diabetes mellitus or modify its presentation. This study aims to evaluate the potential impact of strongyloidiasis in diabetes mellitus and other metabolic diseases. METHODS: Case-control observational retrospective study that included 95 S. stercoralis-infected patients and 83 non-infected individuals. Epidemiological and clinical variables were retrieved from medical records, and a statistical analysis was carried out to explore any association between strongyloidiasis and diabetes mellitus and other metabolic diseases. RESULTS: Most of the patients were men (99, 55.60%) with a mean age of 42.53 ± SD 14 years. Twelve (6.70%) patients were diabetic; 30 (16.90%) presented arterial hypertension; 28 (15.70%) had dyslipidaemia; and 10 (5.60%) had thyroid pathology. When comparing patients with strongyloidiasis and uninfected patients, no differences were found regarding diabetes mellitus or other metabolic diseases. CONCLUSIONS: The results obtained in the present study do not confirm any type of association between strongyloidiasis and diabetes mellitus or other metabolic diseases.

Association of HLA-B∗35 and moderate or severe cutaneous reactions secondary to benznidazole treatment in chronic chagas disease.

OBJECTIVES: Benznidazole is the first-line treatment for Chagas disease. Adverse events appear in more than 50% of patients, leading to discontinuation in approximately 15%. Cutaneous reactions are one of the most frequent adverse events. Human leucocyte antigen (HLA) genotyping studies identified an association between cutaneous reactions to benznidazole and carrying the specific allele HLA-B∗35:05. We designed the present study to prospectively confirm this association. METHODS: This is a prospective observational study including Chagas disease patients aged 18 years or more who accepted to receive benznidazole treatment following current guidelines. Allele genotyping of HLA-B was determined in all patients. Clinical and analytical follow up was performed at days 0, 7, 14, 30 and 60 of treatment. RESULTS: Two-hundred and seven individuals were included. Seventy per cent were female with a mean age of 45.1 (SD ± 9.86) years mainly from Bolivia (92.8%). In 102 (49.3%) cases a cutaneous reaction was diagnosed. Forty-eight (46.6%) were classified as mild, 37 (35.9%) as moderate and 18 (17.5%) as severe. Thirty-two (15.4%) patients had to definitively interrupt the treatment because of a cutaneous reaction. Female sex (OR 4.49; 95% CI 1.62-12.47), new-onset eosinophilia before cutaneous symptoms (OR 2.55; 95% CI 1.2-5.43) and carrying the HLA-B∗35 allelic group (OR 2.58; 95% CI 1.2-5.51) were all predictors of moderate to severe cutaneous reactions. No statistical significance was found when the specific allele HLA-B∗35:05 was analysed. CONCLUSIONS: Patients carrying the HLA-B∗35 allelic group are at higher risk of moderate to severe reactions when taking benznidazole treatment.

Epidemiological and clinical profile of adult patients with diarrhoea after international travel attended in an International Health referral center.

BACKGROUND: The aim of the study is to describe the epidemiological, clinical, and microbiological characteristics of patients with diarrhoea after their return from a trip to tropical and subtropical areas. METHODS: Retrospective study of patients with travel-related diarrhoea attended International Health referral center. Travel diarrhoea was defined as the presence of three or more liquid stools per day, or liquid stools more often than is normal for the individual, during travel or within two weeks after returning. Epidemiological, clinical and microbiological variables were collected. RESULTS: 669 patients were included, 393 (58.7%) were female, with a mean age of 33 (SD 10.7) years. Abdominal pain was present in 59.6% (n = 399), and fever in 44.7% (n = 299). In 43% (n = 280) cases the etiological agent was found. Giardia duodenalis, Enteropathogenic Escherichia coli, and Enterotoxigenic Escherichia coli were the most frequent identified causative agents. Parasitic cause of the diarrhoea was associated to a longer duration of the travel, longer duration of symptoms, and having received pre-travel counseling. CONCLUSIONS: In our cohort, that represents a group of travellers presenting prolonged symptoms after travel, the most frequent causes of diarrhoea were parasitic infections being the most prevalent Giardia duodenalis. This information could be relevant in order to improve travel-related diarrhoea management protocols in this type of patients.

Treatment of Complex Cutaneous Leishmaniasis with Liposomal Amphotericin B.

BACKGROUND: There is no consensus for the best treatment of complex cutaneous leishmaniasis (CL). We aimed to describe a cohort of CL, focusing on liposomal amphotericin B (L-AmB) treatment outcome. METHODS: We performed a retrospective study in Vall d'Hebron University Hospital (Barcelona, Spain). All patients with parasitologically proven CL diagnosed from 2012 to 2018 were included. RESULTS: The analysis included 41 patients with CL. The median age was 39 years (IQR 12- 66); 12 (29%) were children, and 29 (71%) were men. Regarding treatment, 24 (59%) received local treatment, whereas 17 (41%) had complex CL and were offered intravenous systemic treatment. Sixteen patients received L-AmB; eight (50%) had adverse events, and three (19%) discontinued treatment for safety reasons. All cases were considered cured within the first year post-treatment. CONCLUSIONS: L-AmB for complex CL showed no treatment failures, offering an alternative treatment option for patients with complex CL. Clinicians should pay close attention to the potential adverse events of L-AmB and adopt an active drug safety surveillance scheme to rapidly detect reversible side effects.

Epidemiological and clinical profile of immunosuppressed patients with imported strongyloidiasis: a substudy from a larger cohort of the +REDIVI Spanish Collaborative Network.

The aim of this study was to describe the clinical and epidemiological profile of immunosuppressed patients with imported strongyloidiasis in a non-endemic setting, and to compare these results with non-immunosuppressed patients. This is a case-control substudy from a larger observational retrospective study that included all patients with strongyloidiasis registered in the +REDIVI Spanish Collaborative Network. Overall, 1245 patients with imported strongyloidiasis were included. From these, 80 (6.4%) patients had some kind of immunosuppression. Three (3.8%) patients had a hyperinfection syndrome, and 34 (52.3%) patients had eosinophilia. The percentages of positive results of the formalin-ether technique, the fecal culture and serology were 12.3%, 21.1% and 95.4%, respectively. When comparing the main characteristics, immunosuppressed patients had higher proportion of severe clinical manifestations and lower proportion of eosinophilia. No differences were found regarding yield of microbiological techniques and treatment response. These results stress the importance of strongyloidiasis screening among immunosuppressed patients coming from endemic areas. Serological tests have an acceptable sensitivity to be used as a screening tool.

Zika Virus Infection in Tourists Travelling to Thailand: Case Series Report.

Thailand is a popular tourist destination where Zika virus (ZIKV) transmission is currently active. To our knowledge, there are no reports of ZIKV infection imported from Thailand and affecting children. Here, we describe the clinical and microbiological findings in three cases of vector-borne ZIKV infection: An 11-year-old boy, a 2-year-old girl, and her pregnant mother, this last case leading to the prenatal exposure of her second baby to ZIKV in the second trimester of pregnancy. All patients were diagnosed after traveling to Thailand between September 2019 and January 2020. No complications were detected in any patient at follow-up, and the prenatally exposed fetus showed no abnormalities during intensive antenatal health care monitoring. On postnatal study, there were no clinical signs or microbiological findings of mother-to-child ZIKV transmission. ZIKV IgG was initially positive, but seroreversion occurred at 4 months of life. This report describes the clinical and serological evolution of vector-borne ZIKV infection occurring in dengue-naïve tourists returning from Thailand. The World Health Organization currently recommends that pre-travel advice to prevent arbovirus infection should be maintained in travelers to Southeast Asia.

Imported Arbovirus Infections in Spain, 2009-2018.

To determine the epidemiologic and clinical characteristics of patients in Spain with imported arbovirus infections, we analyzed 22,655 records from a collaborative network for January 2009-December 2018. Among 861 arbovirus infections, 845 were monoinfections (456 [53%] dengue, 280 [32.5%] chikungunya, 109 [12.7%] Zika) and 16 (1.8%) were co-infections. Most patients were travelers (56.3%) or immigrants returning to Spain after visiting friends or relatives (31.3%). Median patient age was 37 years; most (62.3%) were women and some (28.6%) had received pretravel advice. Only 12 patients were immunosuppressed. Six cases (all dengue monoinfections, none in immunosuppressed patients) were severe. Since 2014, nondengue arbovirus infections increased; until 2016, chikungunya and Zika were most common. Imported arbovirus infections (mostly dengue) were frequently diagnosed, although increased chikungunya and Zika virus infections coincided with their introduction and spread in the Americas. A large proportion of cases occurred in women of childbearing age, some despite receipt of pretravel advice.

Usefulness of real-time PCR during follow-up of patients treated with Benznidazole for chronic Chagas disease: Experience in two referral centers in Barcelona.

BACKGROUND: Antitrypanosomal treatment with Benznidazole (BZ) or Nifurtimox may be recommended for patients with chronic Chagas disease (CD) to reduce the onset or progression of symptoms. However, such treatment has limited efficacy and high level of toxic effects. In addition, the current cure biomarker (serology conversion) precludes any treatment assessment unless a prolonged follow-up is arranged. PCR is thus the most useful, alternative surrogate marker for evaluating responses to treatment. The aim of this study is to describe the usefulness of real-time PCR in monitoring BZ treatment within a large cohort of chronic CD cases in Barcelona. METHODOLOGY/PRINCIPAL FINDINGS: A total of 370 chronic CD patients were monitored with real-time PCR post-BZ treatment. The median follow-up was 4 years (IQR 2.2-5.3y), with a median of 3 clinical visits (IQR 2-4). Only 8 patients (2.2%) presented with at least one incident of positive real-time PCR after treatment and were therefore considered as treatment failure. Four of those failure patients had completed full course treatment, whereas the remaining cases had defaulted with a statistical difference between both groups (p = 0.02). Half of the failure patients had undergone less than 4 years of follow-up monitoring all presented with parasitemia before treatment. CONCLUSIONS/SIGNIFICANCE: BZ treatment failure was highly infrequent in our cohort. BZ discontinuation was a risk factor for positive real-time PCR results during clinical follow-up. Regular testing with real-time PCR during follow-up allows for early detection of treatment failure in patients with chronic CD.

Strongyloidiasis screening in migrants living in Spain: systematic review and meta-analysis.

OBJECTIVES: To provide information regarding the prevalence of strongyloidiasis among migrants coming from Strongyloides stercoralis-endemic areas who reside in Spain. METHODS: Systematic review of the literature and meta-analysis of studies showing prevalence of S. stercoralis infection among migrants from Latin America, Africa, Eastern Europe, Asia and Oceania who reside in Spain. We included articles published until 30 April 2019 without language restriction. The keywords used for the search included 'Strongyloides stercoralis', 'strongyloidiasis', 'Spain', 'screening' and 'migrants'. RESULTS: Twenty-four studies were included in the review and meta-analysis, comprising 12 386 screened people. Eleven studies (7020 patients) evaluated the presence of S. stercoralis infection only through investigation of larvae in faeces, showing an overall prevalence of 1% (95%CI 1-1%). Thirteen studies (5366 patients) used a serological test, showing an overall prevalence of 14% (95%CI 11-17%). Strongyloidiasis seroprevalence was 20% (95%CI 15-24%) among migrants from sub-Saharan Africa, 14% (95%CI 10-18%) among those from Latin America and 8% (95%CI 5-11%) among migrants from North Africa. CONCLUSIONS: Migrants coming from strongyloidiasis-endemic areas living in Spain had a high S. stercoralis infection prevalence, particularly those from sub-Saharan Africa and Latin America. This population should be screened using serology as the most sensitive test for S. stercoralis infection. This could be easily implemented at primary care level.

OBJECTIFS: Fournir des informations sur la prévalence de la strongyloïdose parmi les migrants résidant en Espagne et provenant de zones endémiques pour Strongyloides stercoralis. MÉTHODES: Revue systématique de la littérature et méta-analyse des études montrant la prévalence de l'infection à S. stercoralis parmi les migrants d'Amérique latine, d'Afrique, d'Europe de l'Est, d'Asie et d'Océanie qui résident en Espagne. Nous avons inclus des articles publiés jusqu'au 30 avril e 2019 sans restriction de langue. Les mots clés utilisés pour la recherche comprenaient "Strongyloides stercoralis", "strongyloïdose", "Espagne", "dépistage" et "migrants". RÉSULTATS: Vingt-quatre études ont été incluses dans la revue et la méta-analyse, comprenant 12.386 personnes dépistées. Onze études (7.020 patients) ont évalué la présence d'une infection à S. stercoralis uniquement en examinant les larves dans les selles, montrant une prévalence globale de 1% (IC95%: 1-1%). Treize études (5.366 patients) ont utilisé un test sérologique, montrant une prévalence globale de 14% (IC95%: 11-17%). La séroprévalence de la strongyloïdose était de 20% (IC95%: 15-24%) chez les migrants d'Afrique subsaharienne, 14% (IC95%: 10-18%) chez ceux d'Amérique latine et 8% (IC95%: 5-11%) chez ceux d'Afrique du Nord. CONCLUSIONS: Les migrants en provenance de zones d'endémie pour la strongyloïdose vivant en Espagne avaient une prévalence élevée d'infection à S. stercoralis, en particulier ceux d'Afrique subsaharienne et d'Amérique latine. Cette population devrait être dépistée en utilisant la sérologie comme le test le plus sensible pour l' infection à S. stercoralis. Cela pourrait être facilement mis en œuvre au niveau des soins primaires.

Zika virus dynamics in body fluids and risk of sexual transmission in a non-endemic area.

OBJECTIVE: To understand Zika virus (ZIKV) dynamics in fluids of infected individuals and the risk of sexual transmission. METHODS: Prospective study at two centres in Spain. Patients with probable or confirmed diagnosis of ZIKV infection were clinically followed up, and fluid samples were collected from saliva, serum, urine and semen or vaginal secretion following the study protocol. Non-traveller-sexual partners were offered to participate. RESULTS: From January 2016 to December 2016, we included a total of 11 traveller patients and six sexual contacts. Six patients were male, with a median age of 38 years (IQR 30-45). We performed 61 RT-PCR determinations, seven of which were positive. Positive results were retrieved from serum, urine, semen and vaginal tract. One of four women tested positive for ZIKV RNA in vaginal swabs collected during the first 45 days after symptoms onset. Clearance occurred between day 37 and day 69 after symptoms onset. One of five men tested positive for ZIKV RNA in semen collected during the first 45 days after symptoms onset. Clearance occurred between day 23 and 107 after symptoms onset. Six patients had sexual relations during the defined period. All tested patients were negative for ZIKV infection by serological testing. CONCLUSION: ZIKV shedding persistence in genital fluids occurs in a significant number of symptomatic patients after visiting an endemic area. We did not find any ZIKV seroconversion among the three male contacts who were investigated. Diagnostic algorithms may be updated to include genital tract fluid specimens in the diagnostic process.

The Use of Quinacrine in Nitroimidazole-resistant Giardia Duodenalis: An Old Drug for an Emerging Problem.

Background: There is little evidence regarding the management of refractory giardiasis after treatment with nitroimidazoles. This study estimates the proportion of persistent giardiasis in 3 hospitals in Barcelona, describes associated risk factors and genotype, and evaluates the efficacy rate of quinacrine in those with persistent giardiasis. Methods: A clinical, prospective, observational study was conducted in patients with giardiasis treated with nitroimidazoles. Those with persistent giardiasis were provided quinacrine. Molecular characterization of Giardia isolates was performed by polymerase chain reaction amplification of a fragment of tpi and bg genes. Results: Seventy-seven patients were recruited and treated with nitroimidazoles, and in 14 of 71 (20%) of patients followed up, Giardia persisted. Refractory giardiasis was associated with malaise (P = .007) and anorexia (P = .02), with previous giardiasis (P = .03), and with previous antibiotic (P = .02) or antiparasitic(P = .04) use. Quinacrine had an effectiveness rate of 100% in refractory giardiasis (n = 13; 95% confidence interval = 75-100). Molecular characterization showed that 17 (25%) Giardia isolates belonged to assemblage A, and 31 (43%) belonged to assemblage B. In refractory giardiasis, assemblage A and B were found responsible in 4 and 6 cases, respectively. Conclusions: Almost 20% of patients presented persistent giardiasis, belonging to both assemblages A and B, after nitroimidazole. Short course of quinacrine was effective in treating refractory cases. Further controlled studies should evaluate its efficacy and safety.