Digenea Carus, 1863 represent a highly diverse group of parasitic platyhelminths that infect all major vertebrate groups as definitive hosts. Morphology is the cornerstone of digenean systematics, but molecular markers have been instrumental in searching for a stable classification system of the subclass and in establishing more accurate species limits. The first comprehensive molecular phylogenetic tree of Digenea published in 2003 used two nuclear rRNA genes (ssrDNA = 18S rDNA and lsrDNA = 28S rDNA) and was based on 163 taxa representing 77 nominal families, resulting in a widely accepted phylogenetic classification. The genetic library for the 28S rRNA gene has increased steadily over the last 15 years because this marker possesses a strong phylogenetic signal to resolve sister-group relationships among species and to infer phylogenetic relationships at higher levels of the taxonomic hierarchy. Here, we have updated the database of 18S and 28S rRNA genes until December 2017, we have added newly generated 28S rDNA sequences and we have reassessed phylogenetic relationships to test the current higher-level classification of digeneans (at the subordinal and subfamilial levels). The new dataset consisted of 1077 digenean taxa allocated to 106 nominal families for 28S and 419 taxa in 98 families for 18S. Overall, the results were consistent with previous higher-level classification schemes, and most superfamilies and suborders were recovered as monophyletic assemblages. With the advancement of next-generation sequencing (NGS) technologies, new phylogenetic hypotheses from complete mitochondrial genomes have been proposed, although their power to resolve deep levels of trees remains controversial. Since data from NGS methods are replacing other widely used markers for phylogenetic analyses, it is timely to reassess the phylogenetic relationships of digeneans with conventional nuclear rRNA genes, and to use the new analysis to test the performance of genomic information gathered from NGS, e.g. mitogenomes, to infer higher-level relationships of this group of parasitic platyhelminths.

Cystic echinococcosis (CE) caused by Echinococcus granulosus sensu lato (s.l.) is a significant zoonosis, especially in developing countries of the Middle East, with many studies focusing on CE genotypes in Iran. We performed a systematic review to determine the exact status of E. granulosus genotypes in the country. We explored English (Pubmed, Scopus, ISI Web of Science and Science Direct) and Persian (Magiran, Iran Medex and Scientific Information Database) databases along with Google Scholar. Our review included 73 studies published prior to the end of 2015. In total, 2952 animal (intermediate and definitive) hosts were examined, and the prevalent genotypes comprised G1 (92.75%) and G6 (4.53%) in sheep, cattle, camels, goats and buffaloes; G3 (2.43%) in five herbivore hosts and dogs; G7 (0.2%) in sheep and goats; and G2 (0.06%) in dogs. G1 was mostly dominant in West Azerbaijan, whereas G3 and G6 were identified most frequently in the provinces of Isfahan and Fars, respectively. Regarding human CE infection, 340 cases were reported from Iran, with the identified genotypes G1 (n = 320), G6 (n = 13) and G3 (n = 7). Most CE-infected humans originated from Isfahan province (168 cases), whereas the lowest number of infected persons was noted in Kerman province (two cases). The information obtained from this systematic review is central to better understanding the biological and epidemiological characteristics of E. granulosus s.l. genotypes in Iran, leading to more comprehensive control strategies.

Marine mammals are long-lived top predators with vagile lifestyles, which often inhabit remote environments. This is especially relevant in the oceanic waters around New Zealand and Australia where cetaceans and pinnipeds are considered as vulnerable and often endangered due to anthropogenic impacts on their habitat. Parasitism is ubiquitous in wildlife, and prevalence of parasitic infections as well as emerging diseases can be valuable bioindicators of the ecology and health of marine mammals. Collecting information about parasite diversity in marine mammals will provide a crucial baseline for assessing their impact on host and ecosystem ecology. New studies on marine mammals in New Zealand and Australian waters have recently added to our knowledge of parasite prevalence, life cycles and taxonomic relationships in the Australasian region, and justify a first host–parasite checklist encompassing all available data. The present checklist comprises 36 species of marine mammals, and 114 species of parasites (helminths, arthropods and protozoans). Mammal species occurring in New Zealand and Australian waters but not included in the checklist represent gaps in our knowledge. The checklist thus serves both as a guide for what information is lacking, as well as a practical resource for scientists working on the ecology and conservation of marine mammals.

Parasites are often overlooked in the construction of food webs, despite their ubiquitous presence in almost every type of ecosystem. Researchers who do recognize their importance often struggle to include parasites using classical food-web theory, mainly due to the parasites' multiple hosts and life stages. A novel approach using compound-specific stable-isotope analysis promises to provide considerable insight into the energetic exchanges of parasite and host, which may solve some of the issues inherent in incorporating parasites using a classical approach. Understanding the role of parasites within food webs, and tracing the associated biomass transfers, are crucial to constructing new models that will expand our knowledge of food webs. This mini-review focuses on stable-isotope studies published in the past decade, and introduces compound-specific stable-isotope analysis as a powerful, but underutilized, newly developed tool that may answer many unresolved questions regarding the role of parasites in food webs.

This catalogue is concerned with the closely related angiostrongylid genera Angiostrongylus, Gallegostrongylus, Rodentocaulus and Stefanskostrongylus. Three species, Angiostrongylus cantonensis, A. costaricensis and A. vasorum, have attracted most attention because of their importance in human and domestic animal disease. Many of the remaining species are poorly known and the number of valid taxa is unclear. The catalogue lists all nomenclaturally available and unavailable genus-group and species-group names that have been applied to the above genera and the species included in them, indicating their current nomenclatural status and providing the rigorous nomenclatural basis for future work. The catalogue lists 14 published and nomenclaturally available genus-group names, with the above four treated as valid, the other ten being junior synonyms. There are 42 published species-group names: 36 are valid, two are junior synonyms, four are nomenclaturally unavailable. One additional species, described in Chabaudistrongylus (synonym of Angiostrongylus), is listed as incertae sedis in Angiostrongylidae. Also listed are two unpublished collection names. The catalogue provides bibliographic details for all published names, and for available names provides locations of type material, details of type localities, geographic distributions and details of type and other hosts, both definitive and intermediate, to the extent known. The catalogue is a work of nomenclature, not a revisionary taxonomic work. No new names or new combinations are proposed. The apparently new family-group synonymy of Cardionematinae with Angiostrongylidae is introduced, as are four genus-group synonymies, three with Angiostrongylus and one with Stefaskostrongylus.

Efficacious therapeutic strategies against lymphatic filariasis are always sought after. However, natural products are a promising resource for developing effective antifilarial agents. Azadirachtin, a significant tetranortriterpenoid phytocompound found in Azadirachta indica, was evaluated in vitro for antifilarial potential against the filarial parasite Setaria cervi. Dye exclusion and MTT assay confirmed the antifilarial potential of azadirachtin against S. cervi with a median lethal dose (LC50) of 6.28 μg/ml for microfilariae (mf), and 9.55 μg/ml for adult parasites. Morphological aberrations were prominent in the histological sections of the azadirachtin-exposed parasites. Moreover, alterations in the reactive oxygen species (ROS) parameters in treated parasites were evident. Induction of apoptosis in treated parasites was confirmed by DNA laddering, acridine orange (AO)/ethidium bromide (EtBr) double staining and in situ DNA fragmentation. The downregulation of anti-apoptotic CED-9 and upregulation of proapoptotic EGL-1, CED-4 and CED-3 at both the transcription and translation levels confirmed apoptosis execution at the molecular level. Changes in the gene expressions of nuc-1, cps-6 and crn-1 further clarified the molecular cause of DNA degradation. Furthermore, azadirachtin was found to be non-toxic in both in vitro and in vivo toxicity analyses. Therefore, the experimental evidence detailed the pharmacological effectiveness of azadirachtin as a possible therapeutic agent against filariasis.

Toxocariasis is an important neglected tropical disease that has been suggested as a possible etiologic agent of asthma. The objective of the present study was to investigate possible significant association between Toxocara seroprevalence and asthma in a clinic-based case-control study. Blood samples were collected from human subjects aged 5–70 years, 50 of whom had signs of asthma and 50 of whom had no signs of asthma. Risk factors for asthma and Toxocara spp. infection were assessed by a questionnaire given to each patient. Blood samples were analysed to measure levels of anti-Toxocara spp. immunoglobulin G (IgG). Patients with bronchial asthma were observed to have higher Toxocara spp. seropositivity than that of the non-asthmatic controls (6 vs 2%, P = 0.47). The mean anti-Toxocara spp. antibody titre was not significantly higher in patients with bronchial asthma than in individuals without asthma (P = 0.395, 95% CI = 0.579–1.45). There was no significant difference in the mean age, sex, social class, exposure to smoking and presence of domestic dog or cat at home between the two groups (P ≥ 0.05). The presence of anti-Toxocara spp. IgG was statistically associated with higher blood eosinophils, but it was not associated with asthma (P ≥ 0.05). The observed relationship between exposure to Toxocara spp. infection and bronchial asthma in Iranian patients warrants further evaluation. An understanding of any potential influence on the pathogenesis of human asthma provides a potential avenue for prevention.

In recent decades, parasite community ecology has produced hundreds of studies on an ever-growing number of host species, and developed into an active sub-discipline of parasitology. However, this growth has been characterized by a lack of standards in the practices used by researchers, with many common approaches being flawed, unjustified or misleading. Here, in the hope of promoting advances in the study of parasite community ecology, I identify some of the most common errors or weaknesses in past studies, and propose ten simple rules for best practice in the field. They cover issues including, among others, taxonomic resolution, proper and justifiable analytical methods, higher-level replication, controlling for sampling effort or species richness, accounting for spatial distances, using experimental approaches, and placing raw data in the public domain. While knowledge of parasite communities has expanded in breadth, with more and more host species being studied, true progress has been very limited with respect to our understanding of fundamental general processes shaping these communities. It is hoped that the guidelines presented here can direct researchers away from the entrenched use of certain approaches flawed in design, analysis or interpretation, by offering a more rigorous and standardized set of practices, and, hopefully, a way forward.

Schistosomiasis is a chronic debilitating parasitic disease that causes hepatic damage and is known to be endemic in developing countries. Recent control strategies for schistosomiasis depend exclusively on chemotherapeutic agents, specifically praziquantel. Unfortunately, praziquantel has low efficacy in the early phase of infection, and resistance to treatment is increasingly reported. The aim of this work was to find an alternative treatment by assessing the in vivo activity of aqueous extract of Callistemon citrinus against Schistosoma mansoni in both prepatent and patent phases in experimentally infected mice. The study was conducted on 80 male BALB/c albino mice divided into eight groups. Callistemon was administered at a dose of 200 mg/kg on days 14 and 45 post infection as a single therapy and in combination with praziquantel. Porto-mesenteric worm burden, hepatic and intestinal egg counts, hepatic granuloma number and diameter, and oogram pattern were assessed to evaluate the anti-schistosomal properties of C. citrinus. Liver enzymes and total bilirubin were tested to assess hepatoprotective effects. Results revealed that the use of C. citrinus was associated with a significant decrease in worm burden and tissue egg load together with an increased percentage of dead eggs. In addition, there was a significant reduction in granuloma formation. Callistemon also led to a significant improvement in liver function. The best results were obtained when C. citrinus was given in the prepatent phase of infection and when combined with praziquantel. Although the effects of C. citrinus are considered to be promising, further studies using different extracts, active ingredients and doses are needed.

The aim of this study was to evaluate the pattern of local immune cell infiltration in human cystic echinococcosis (CE) by identifying the subtypes of immune cells using immunohistochemistry (IHC). Fifty surgically removed hydatid cyst samples and surrounding tissues were collected from patients referred to Al-Zahra Hospital, Isfahan, Iran. IHC was performed on the surrounding host tissue of hydatid cysts using anti-human CD3, CD19, CD8, CD4, CD68, CD56, Ki-67 and Foxp3 (forkhead box P3) antibodies. The results were then compared to hepatocellular carcinoma and chronic hepatitis. In the host-tissue reaction site of liver hydatid cysts, a distinct pattern of local immune cell response, which outwardly consisted of a pack of the fibrous elements, a layer of palisading macrophages, an eosinophil-containing layer and a layer of accumulated lymphocytes, was observed. However, in some cases there were no positive cells for CD56+ natural killer cells and Foxp3+ regulatory T cells. The CD3+ T cells were the predominant inflammatory cells in all groups, followed by CD19+ B cells. It can be concluded that different immune cells are involved in the local response to human hydatid cysts.

With the growing incidence of closed schistosomiasis and uncommon presentations, there is a risk of the infection rate being underestimated. A study in Japan reported an unexplained case of endocarditis that was finally diagnosed as a complex Schistosoma japonicum infection; in the absence of advanced techniques, the diagnosis was delayed. We therefore set out to explore the incidence of Schistosoma mansoni in endocarditis patients coming from areas of Egypt where S. mansoni is endemic. We also investigated histopathological changes in the cardiac valves and the presence of cell-free parasite DNA (CFPD) in cardiac tissues of laboratory mice infected with S. mansoni. The study included 186 patients with the manifestations of infective endocarditis. Eggs were detected in the stool samples of 5.91% of patients. Seropositivity was reported in 23.66% of patients and antigen was detected in the urine samples of 10.21%. Using real-time polymerase chain reaction (PCR), CFPD was detected in the blood of 6.98% of the endocarditis patients and 95% of the infected mice, while the cardiac samples of 45% of the mice tested positive for CFPD (means ± SD = 1390.2 ± 283.65, 2158.72 ± 1103.1 and 5.71 ± 2.91, respectively). Histopathological examination revealed abnormal collagen deposition, inflammatory cells and haemorrhagic pigmentation in the heart sections. Despite the low incidence of S. mansoni infection in the studied cohort, the presence of CFPD in the cardiac tissue of infected mice makes it necessary to: (1) investigate the hazards of CFPD deposition in endothelium-rich organs; and (2) test the potential of CFPD to trigger tissue inflammation, abnormal proliferation or genome integration.

This study assessed the efficacy of closantel vis-à-vis herbal extracts with known anti-parasitic properties, against fenbendazole-resistant nematodes in goats maintained under a semi-intensive system of management at the University goat farm, Jabalpur. Fifty goats were randomly assigned to five groups, each comprising 10 animals, irrespective of their breed, age and sex. Each animal in Group I, II and III was orally administered with aqueous leaf extracts of neem (Azadirachta indica) at 1 g/kg body weight, sitaphal (Annona squamosa) at 1.5 g/kg body weight and tobacco (Nicotiana tabacum) at 1 g/kg body weight, respectively, whereas Group IV was an untreated control group. Each animal in Group V was orally treated with closantel at 10 mg/kg body weight. During the course of the study, all animals were maintained under an identical semi-intensive system of management. Compared to the untreated control group (Group IV), there was no conspicuous reduction in post-treatment (day 10) faecal egg counts (FEC) in animals administered with the herbal extracts (Groups I, II and III), which is suggestive of poor anti-parasitic activity. However, using the faecal egg count reduction test (FECRT), the overall efficacy of closantel was recorded as 95.64%. This supports the rotational use of closantel as a preferred choice over the benzimidazole group of anthelmintics and/or herbal extracts to meet the acute challenge of in situ development of drug-resistant gastrointestinal nematodes, especially Haemonchus contortus.

Trichostrongylus spp. are primarily parasites of ruminants, but humans can become infected as accidental hosts. Information about the clinical aspects of human trichostrongyliasis is limited. This study investigated the clinical and haematological characteristics of a large number of trichostrongyliasis patients. In the Fouman district of Guilan Province in northern Iran, during 2015–2016, 60 patients were identified as positive for Trichostrongylus spp., using stool examination methods. The clinical manifestations and demographic data of all patients were recorded and further analysed. Twenty-three patients (38.3%) were male and 37 (61.7%) were female. Among the individuals infected only with Trichostrongylus, only nine patients (16.4%) were asymptomatic. Forty-six patients (83.6%) presented with gastrointestinal (76.3%), pulmonary (30.9%) and cutaneous (12.7%) symptoms. No statistically significant relationship was found between clinical manifestations and sex or age groups. Ten patients (18.1%) revealed eosinophilia and five (9.1%) presented with hypochromic microcytic anaemia. The relationship between eosinophilia and age group, sex and clinical manifestations showed no statistical significance. Our study indicated that trichostrongyliasis may be a major parasitic aetiology for gastrointestinal symptoms and eosinophilia in rural residents of endemic areas.

In this study, we evaluated the in vivo comparative efficacy of ivermectin and Nigella sativa extract against helminths in Aseel chickens, and the effects of helminths on blood parameters before and after treatment in Aseel chickens. Forty naturally infected adult Aseel chickens were randomly divided into four groups (n = 10 each): group A (ivermectin at 300 μg/kg); group B (N. sativa extract at 200 mg/kg); group C (ivermectin at 300 μg/kg + N. sativa extract at 200 mg/kg); group D was kept as a positive control to monitor time-related changes. On day 28 post treatment, the mean percentages of faecal egg-count reduction (FECR %) in groups A, B and C were recorded as 93.58, 88.09 and 100.00%, respectively. Further data analysis showed significantly higher efficacy in group C (100 ± 0.00%) than in groups A and B (P < 0.001). Highly significant (P < 0.001) improvements in mean percentage values of packed cell volume (PCV %) were recorded in groups A and C on days 14 and 28 post treatment. Meanwhile, the improvements in mean values of haemoglobin (Hb) concentration in groups A, B and C were highly significant (P < 0.001) when compared to that of group D on day 28 post treatment. The synergistic combination of ivermectin and N. sativa extract possessed greater efficacy than either ivermectin or N. sativa extract used alone. Furthermore, both PCV % and Hb concentration values gradually increased in the treated groups compared to the control group, in which PCV % and Hb concentration gradually decreased throughout the trial.

The transmembrane protein, ARV1, plays a key role in intracellular sterol homeostasis by controlling sterol distribution and cellular uptake. To date, only the ARV1s from yeast and humans have been characterized to some extent. In this study, the ARV1 of an animal filarial parasite, Setaria digitata (SdARV1), was characterized; its cDNA was 761 bp and encoded a protein of 217 amino acids, with a predicted molecular weight of 25 kDa, containing a highly conserved ARV1 homology domain and three transmembrane domains in the bioinformatic analyses. Information required to cluster members belonging to a particular taxon has been revealed in phylogenetic analyses of ARV1 sequences derived from different organisms. Reverse transcription-polymerase chain reaction (RT-PCR) analyses indicated that SdARV1 was expressed in different developmental stages – microfilariae and adult male and female worms. Experiments carried out with a single copy of the SdARV1 under the control of the PMA-1 promoter in a temperature-sensitive Saccharomyces cerevisiae mutant strain indicated full complementation of the mutant phenotype, with growth at a non-permissive temperature (37°C). Microscopic observations of cellular morphology with Gram staining revealed alteration of the shape from shrunken to oval, in mutant and complemented strains, respectively. Assessment of free sterol levels extracted from mutant yeast and complemented strains indicated that the level of sterol was significantly higher in the former compared to the latter, which had sterol levels similar to those of the wild type. Thus, the results of the current study suggest that SdARV1 is ubiquitously expressed in different developmental stages of S. digitata, and that it is a true functional homologue of mammalian and yeast ARV1s, which have crucial phylogenetic information that follows classical evolutionary trends. Finally, this is the first study to report the biological function of nematode ARV1.

As part of the international joint projects working towards the control of taeniosis/cysticercosis in Asia Pacific, epidemiological studies on Taenia solium cysticercosis have been carried out in high-incidence populations, such as minority groups in Thailand. To assess the epidemiology of cysticercotic infections in pigs in the hill-tribe minority villages (Karen) in Tak province, Thailand, we conducted serological screening and necropsies. The patterns of antibody response to T. solium antigens were then investigated using immunoblot assays. Of the 188 pig serum samples tested for antibody responses to partially purified low-molecular-weight antigens of T. solium cyst fluid, positive responses were detected in 37 samples (19.7%). Based on these results, 16 pigs (10 seropositive and 6 seronegative) were necropsied for investigation of cysticerci and intestinal parasites. All seropositive pigs were coinfected with both T. solium and Taenia hydatigena cysticerci, except one, which was infected with T. hydatigena alone. Three of the six seronegative pigs were confirmed to be infected with T. hydatigena. Pigs infected with T. solium showed much stronger antibody responses than those infected with T. hydatigena. Our results demonstrate the co-occurrence of two swine cysticercoses due to T. solium and T. hydatigena in the studied areas. This study also reveals the importance of direct confirmation of the presence of cysticerci by necropsy after serological screening. In addition to the prevalence of swine cysticercosis in these endemic areas, our findings also reveal potential implications for the development of serological diagnostic assays for swine cysticercosis.

Despite the seriousness of schistosomiasis, its treatment depends only on praziquantel (PZQ), which has begun to lose its efficacy against the emergent Schistosoma mansoni-resistant strains. Therefore, the discovery of a novel schistosomicidal drug is an urgent priority. This study was designed to evaluate treatment with Cucurbita pepo L. (pumpkin) seed oil (PSO) alone and combined with PZQ against S. mansoni in experimentally infected mice. The study involved five groups: GI was the normal control; GII was the infected control; GIII was treated with an oral dose of PZQ of 500 mg/kg/day for two successive days, starting in the sixth week post infection; GIV was treated with an oral dose of PSO of 50 mg/kg/day for four weeks, starting in the fourth week post infection; and GV was treated with combined PSO–PZQ. Worm burden, tissue egg load and oogram pattern were estimated, and the ultrastructure alterations were examined. Histopathological examination of granuloma diameters, collagen deposition (Picro Sirius red stain), and angiogenesis (immunohistochemical expression of CD34+) was conducted and serum liver enzymes were measured to assess the liver condition. Moreover, the oxidative stress was evaluated by determining the amounts of malondialdehyde and superoxide dismutase in liver homogenates. The results revealed significant changes in all the assessed parameters with PSO administration. However, PZQ was significantly more effective as an antiparasitic agent, whereas PSO was better in terms of fibrosis and oxidative stress. The most significant results were obtained in group V, which may be attributed to a synergy between PZQ and PSO, with antiparasitic, antioxidant and antifibrotic properties.

The in vitro nematicidal effect of Chenopodium ambrosioides and Castela tortuosa n-hexane extracts (E-Cham and E-Cato, respectively) on Haemonchus contortus infective larvae (L3) and the anthelmintic effect of these extracts against the pre-adult stage of the parasite in gerbils were evaluated using both individual and combined extracts. The in vitro confrontation between larvae and extracts was performed in 24-well micro-titration plates. The results were considered 24 and 72 h post confrontation. The in vivo nematicidal effect was examined using gerbils as a study model. The extracts from the two assessed plants were obtained through maceration using n-hexane as an organic agent. Gerbils artificially infected with H. contortus L3 were treated intraperitoneally with the corresponding extract either individually or in combination. The results showed that the highest individual lethal in vitro effect (96.3%) was obtained with the E-Cham extract at 72 h post confrontation at 40 mg/ml, followed by E-Cato (78.9%) at 20 mg/ml after 72 h. The highest combined effect (98.7%) was obtained after 72 h at 40 mg/ml. The in vivo assay showed that the individual administration of the E-Cato and E-Cham extracts reduced the parasitic burden in gerbils by 27.1% and 45.8%, respectively. Furthermore, the anthelmintic efficacy increased to 57.3% when both extracts were administered in combination. The results of the present study show an important combined nematicidal effect of the two plant extracts assessed against L3 in gerbils.

Ascaris sp. is a soil-transmitted helminth (STH) significantly affecting the health of human and swine populations. Health inequities and poverty, with resulting deficiencies in water, sanitation and hygiene, are directly associated with Ascaris lumbricoides prevalence in humans. Resource constraints also lead to small-scale livestock production under unsanitary conditions. Free-ranging pigs, for instance, are exposed to a number of infectious agents, among which Ascaris suum is one of the most common. Under these conditions, close proximity between people and pigs can result in cross-contamination; that is, pigs harbouring human Ascaris and vice versa. Moreover, the potential interbreeding between these two Ascaris species has been demonstrated. The present study analysed Ascaris worms obtained from children and pigs in Honduras. Adult worms were collected from stool samples of children after pharmacological treatment, and from pigs’ intestines after slaughter for commercial purposes at a local abattoir. A nuclear ribosomal internal transcribed spacer (ITS) region was amplified by polymerase chain reaction (PCR) and digested with a restriction enzyme in order to separate putative human- and pig-derived Ascaris isolates. PCR products were also sequenced, and cladograms were constructed. All parasites isolated from children showed the typical human-derived genotype of Ascaris, whereas 91% of parasites from pigs showed the expected pig-derived genotype. Cross-infections between hosts were not demonstrated in this study. Nine per cent of pig-derived worms showed a restriction band pattern highly suggestive of a hybrid human–pig Ascaris genotype. These results contribute to the understanding of ascariasis epidemiology and its zoonotic potential in a highly endemic region.

Alcoholic patients are more susceptible to Strongyloides stercoralis infection. The chronic use of alcohol raises the levels of endogenous corticosteroids, which regulates the development of larvae and stimulates the differentiation of rhabditiform into infective filariform larvae, thus inducing internal autoinfection. Therefore, early diagnosis is important to prevent severe strongyloidiasis. The aim of this study was to evaluate the efficacy of parasitological methods, according to the parasite load and the number of stool samples, for diagnosis of S. stercoralis infection, as well the peripheral blood eosinophil count in alcoholic patients. A total of 330 patients were included in this study. The diagnosis was established using three parasitological methods: agar plate culture, Baermann–Moraes method and spontaneous sedimentation. Peripheral eosinophilia was considered when the level was >600 eosinophils/mm3. The agar plate culture (APC) had the highest sensitivity (97.3%). However, the analysis of multiple samples increased the sensitivity of all parasitological methods. The sensitivities of the methods were influenced by the parasite load. When the larval number was above 10, the sensitivity of APC was 100%, while in spontaneous sedimentation the sensitivity reached 100% when the larval number was above 50. In the present study, 15.4% of alcoholic patients infected with S. stercoralis (12/78) had increased peripheral blood eosinophil count (above 600 eosinophils/mm3). For an efficient parasitological diagnosis of S. stercoralis infection in alcoholic patients, repeated examination by two parasitological methods must be recommended, including agar plate culture due to its higher sensitivity. Moreover, S. stercoralis infection was associated with eosinophilia, mostly in patients excreting up to 10 larvae/g faeces.