To compare the efficacy of stool examination for the detection of Strongyloides stercoralis and hookworm, a total of 634 stool samples from the routine laboratory service of the Pharmacia Faculty, Federal University of Bahia, Brazil, were examined by agar plate culture (APC), Baermann-Moraes and spontaneous sedimentation. The sensitivity of agar plate culture, calculated by combining results of all 3 methods, was 95% for S. stercoralis and 77.6% for hookwoorm. Moreover, APC had superior accuracy than Baermann-Moraes and spontaneous sedimentation for S. stercoralis and hookworm diagnosis, respectively. The S. stercoralis and hookworm positive samples from the laboratory routine, obtained after the previous analysis, along with those initially selected, were used to evaluate the concordance between microscopic examination and both the type of furrows left by larvae and the time for culture positivity using the APC method. Of 115 stool samples positive for S. stercoralis and 92 positive for hookworm, 110 (95.7%) and 89 (96.7%), respectively, had concordant results for furrows and morphological characteristics. The cumulative percentage of positivity increased to 94% by the third day of observation; at this time, only 19.6% of hookworm-positive samples had positive culture plates. Analyses of 74 S. stercoralis-positive stool samples stored at 4°C for 24, 48 and 72h showed the presence of larvae in 48.6%, 28.4% and 23% of samples, respectively when re-examined by the APC. As a definitive diagnosis of strongyloidiasis depends on the microscopic demonstration of parasites, increasing the sensitivity of the detection requires the use of different parasitological methods, including APC.

A higher prevalence of Strongyloides stercoralis infections has been reported in alcoholic patients compared to nonalcoholic patients living in the same area. Excessive alcohol consumption increases the levels of endogenous corticosteroids that subsequently enhance the fecundity of S. stercoralis parthenogenetic females. These corticosteroids also enhance the transformation of rhabditiform larvae into infective filariform larvae by mimicking the effect of the ecdysteroid hormones produced by the parasite, thus leading to autoinfection. In addition, alterations in the intestinal barrier and host immune response contribute to the development of hyperinfection and severe strongyloidiasis in alcoholic patients. The aim of this study was to evaluate the frequency of S. stercoralis infections in alcoholic patients and to determine the association between S. stercoralis infection and endogenous cortisol levels. The frequency of infection was evaluated in 332 alcoholic and 92 nonalcoholic patients. The parasitological diagnosis was carried out by agar plate culture, the modified Baermann-Moraes method and spontaneous sedimentation. The immunological diagnosis was performed using an ELISA with anti-S. stercoralis IgG. The cortisol levels were measured in serum samples by ELISA. The frequency of S. stercoralis infection in alcoholic patients was 23.5% (78/332), while in nonalcoholic patients, it was 5.4% (5/92) (p<0.05). The cortisol levels were higher in alcoholic than in nonalcoholic patients (p<0.05). However, among the alcoholic patients, the cortisol levels did not differ between S. stercoralis-infected and uninfected patients (p>0.05). As demonstrated in this work, 81.3% (26/32) of patients with a high parasite load, considered as more than 11 larvae per gram of feces, presented serum cortisol levels above the normal reference value (24 mg/dL). High endogenous cortisol levels in alcoholic patients were not associated to susceptibility to S. stercoralis infection, however once infected, this may lead to a high parasite load.

Strongyloides stercoralis infection is endemic in many tropical and subtropical areas. The parasite has the unusual ability to multiply inside the host due to the transformation of rhabditiform larvae into infective filariforms. Several studies have shown that chronic alcoholism is an important factor that predisposes to strongyloidiasis. The increased susceptibility to S. stercoralis infections seen in alcoholic individuals could be explained by their increased exposure to the parasite, malnutrition, breakdown of local immune responses, and/or alterations in intestinal barriers. Moreover, ethanol intoxication can elevate human endogenous corticosterone, which, in turn, suppresses T cell function and increases the fecundity and survival of the parasite, mimicking the effect of worm ecdysteroides. Although chronic alcoholism is a risk factor for nematode infection, most cases of hyperinfection or dissemination are associated with the presence of hepatic cirrhosis or strongyloidiasis-related symptoms. The present study describes a case of S. stercoralis hyperinfection in a 51-yr-old male patient without gastrointestinal or pulmonary symptoms and with previous anemia and chronic alcoholism. He was not receiving glucocorticoid therapy and tested negative for HTLV and human immunodeficiency virus (HIV), but he had a history of alcohol addiction for more than 20 yr. Laboratory test results showed increased eosinophilia and a high immunoglobulin E (IgE) level, which may have temporarily protected the patient from dissemination of infection, but not prevented proliferation of the parasite, as shown by the large number of S. stercoralis larvae recovered using the Baermann method. Evaluation for strongyloidiasis should occur in alcoholics, especially in endemic areas, to prevent occult asymptomatic infections from progressing to life-threatening cases.

Carbohydrates of pathogen antigens have been disrupted by periodate oxidation, in order to reduce nonspecific bindings and improve serodiagnosis of parasite infections. In the present study, the enzyme-linked immunosorbent assay (ELISA) was carried out with filariform larvae antigen treated, or not treated, with sodium metaperiodate. Groups of sera from patients with Strongyloides stercoralis infection, with other intestinal parasites and a normal control, were used. The oxidation of Strongyloides stercoralis glycosylated epitopes reduced the seroreactivity of sera from patients with S. stercoralis infection as demonstrated by ELISA, with a decrease in sera optical densities. The number of cross-reactions of IgG and IgE-ELISAs increased by 12% and 16%, respectively, after antigen treatment with metaperiodate. This was more often observed in patients infected with Schistosoma mansoni and hookworm. Moreover, the IgG depletion from sera tested by IgE-ELISA led to the detection of previous false-negative samples from S. stercoralis-infected patients.

No abstract

Aim: Strongyloides stercoralis infection is usually chronic and asymptomatic and may persist undiagnosed for decades. However, in immunocompromised individuals, the infection can cause hyperinfection and dissemination. Therefore, early diagnosis is essential to prevent severe forms of strongyloidiasis. The aims of this study were: (i) to evaluate the frequency of S. stercoralis infection in patients with systemic lupus erythematous (SLE) and (ii) to estimate specific immunoglobulins G (IgG) and E (IgE) production using an enzyme-linked immunosorbent assay (ELISA) method.Methods: Seventy-five SLE patients treated with prophylactic anthelmintic therapy were evaluated using the spontaneous sedimentation (SS), Baermann-Moraes (BM) and agar plate culture (APC) methods. Serum anti-S. stercoralis IgG and IgE antibodies were measured by ELISA.Results: Using parasitological methods, the frequency of intestinal parasites was 10.7%, whereas the frequency of S. stercoralis infection was 1.3%. The sensitivity of the ELISA to detect anti-S. stercoralis IgG and IgE was 80% and 76.9%, respectively. Both assays presented the same specificity of 96.7%. The frequency of anti-S. stercoralis IgG and IgE was 16% and 28%, respectively. Six patients were positive for both antibodies.Conclusions: Diagnostic approaches using high-sensitivity parasitological methods and the detection of specific antibodies are essential for the diagnosis of strongyloidiasis in immunocompromised patients. Early detection of infection can alter the course of the disease via appropriate treatment, preventing the occurrence of severe strongyloidiasis.

Introduction:The diagnosis of intestinal parasitic infections depends on the parasite load, the specific gravity density of the parasite eggs, oocysts or cysts, and the density and viscosity of flotation or sedimentation medium where faeces are processed. Objective: To evaluate the concordance between zinc sulphate flotation and centrifugal sedimentation in the recovery of parasites in faecal samples of children. Materials and methods: Faecal samples of 330 children from day care centers were evaluated by zinc sulphate flotation and centrifugal sedimentation techniques. The frequencies of detection of parasites by each method were determined and the agreement between the diagnostic techniques was evaluated using the kappa index, with 95% confidence intervals. Results: The faecal flotation in zinc sulphate diagnosed significantly more cases of Trichuris trichiura infection when compared to centrifugal sedimentation (39/330; 11.8% vs. 13/330; 3.9%, p<0.001), with low diagnostic concordance between methods (kappa=0.264; 95% CI: 0.102-0.427). Moreover, all positive samples for Enterobius vermicularis eggs (n=5) and Strongyloides stercoralis larvae (n=3) were diagnosed only by zinc sulphate. No statistical differences were observed between methods for protozoa identification. Conclusions:The results showed that centrifugal flotation in zinc sulphate solution was significantly more likely to detect light helminths eggs such as those of T. trichiura and E. vermicularis in faeces than the centrifugal sedimentation process.

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:HyphenationZone>21</w:HyphenationZone> <w:PunctuationKerning /> <w:ValidateAgainstSchemas /> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables /> <w:SnapToGridInCell /> <w:WrapTextWithPunct /> <w:UseAsianBreakRules /> <w:DontGrowAutofit /> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--> <p class="MsoNormal" style="margin: 0cm 22.7pt 0.0001pt; text-align: justify;"><span style="font-size: 8pt; color: black;">O diagnóstico definitivo da estrongiloidíase é realizado pela pesquisa de larvas nas fezes, utilizando-se principalmente o método de Baermann-Moraes, apesar da cultura em placa de ágar (CPA) apresentar maior sensibilidade. Além da finalidade diagnóstica, a CPA pode ser utilizada no cultivo das larvas de <em>Strongyloides stercoralis</em> para a produção de antígenos. Entretanto, as fezes têm muito detritos de alimentos e bactérias, o que prejudica a separação das larvas em uma suspensão limpa. O objetivo deste trabalho foi aperfeiçoar o protocolo da recuperação das larvas filarioides de <em>S. stercoralis</em> das culturas em placas de ágar, comparando três métodos: (a) a lavagem das superfícies das placas de ágar com tampão fosfato-salina e (b) o método de Baermann-Moraes de todo o material contido nas placas (fezes e ágar) ou (c) somente com as fezes retiradas das placas, após o período de incubação das culturas. Além disso, foi avaliada a recuperação de larvas filariodes de culturas contendo estreptomicina e anfotericina. O procedimento de lavagem manual das superfícies das placas recuperou um número maior de larvas, quando comparado com os outros dois métodos (<em>P</em> <0,05, <em>Teste t</em>). O tempo ideal de incubação das culturas para a recuperação das larvas foram os três primeiros dias de incubação (<em>P </em><0,05), enquanto que a maior quantidade de vermes adultos foi observada no quarto dia, porém sem significância estatística. A adição de antibiótico e antifúngico ao meio de cultura forneceu uma quantidade de larvas significativamente superior àquela das placas controle (<em>P </em><0,05), sugerindo uma inibição parcial do desenvolvimento <em>in vitro</em> do <em>S. stercoralis</em> por bactérias e/ou fungos. </span></p> <p class="MsoNormal" style="margin: 0cm 22.7pt 0.0001pt;"><span style="font-size: 8pt; color: black;" lang="EN-US"> </span></p> <p class="MsoNormal" style="margin: 0cm 22.7pt 0.0001pt;"><strong><em><span style="font-size: 8pt; color: black;" lang="EN-US">Abstract</span></em></strong></p> <p class="MsoNormal" style="margin: 0cm 22.7pt 0.0001pt; text-align: justify;"><span style="font-size: 8pt; color: black;" lang="EN-US">The definitive diagnosis of strongyloidiasis is performed by searching larvae in the feces, using mainly the method of Baermann-Moraes, despite the higher sensitivity of agar plate culture (APC). In addition to the diagnostic purpose, the APC can be used for cultivation of the <em>Strongyloides stercoralis</em> larvae to produce antigens. However, the stools have many food debris and bacteria, which hamper the separation of larvae in a clean suspension. The objective of this study was to improve the protocol of <em>S. stercoralis</em> infective larvae recovery from APC, by comparing three methods: (a) the washing of the agar plate surfaces with phosphate-buffered saline and (b) the method of Baermann-Moraes of the entire material of the plates (feces and agar) or (c) only with the feces removed from the plates, after the incubation period. Moreover, the recovery of the filarioid larvae from cultures containing streptomycin and amphotericin was evaluated. The procedure for manual washing of the plates surfaces recovered a greater number of larvae compared to the other two methods (<em>P</em> <0.05, t test). The optimal time of cultures incubation for the recovery of larvae was the first three days (<em>P</em> <0.05), while a higher number of adult worms was observed by the fourth day, although not statically significant (<em>P </em>>0.05). The addition of antibiotic and antifungal to the cultures medium provided a significantly higher number of larvae, when compared to the control plates (<em>P</em> <0.05), suggesting a partial inhibition of the <em>in vitro</em> development<em> </em>of <em>S. stercoralis</em> by bacteria and/or fungi.</span></p>