Innovative approaches to improve serodiagnosis of Strongyloides stercoralis infection

Strongyloidiasis is a helminthiasis of neglected condition that has no gold standard parasitological diagnosis due to the intermittent release of larvae in feces. This study aimed to use an scFv (single chain variable fragment) obtained by Phage Display, previously validated to detect immune complexes in serum samples from individuals infected with Strongyloides stercoralis by enzyme-linked immunosorbent assay (ELISA). Now the ability of scFv to detect the immune complexes was verified by immunofluorescence, flow cytometry using magnetic beads and surface plasmon resonance (SPR). As ELISA, the SPR, immunofluorescence and flow cytometry demonstrated the ability of scFv to detect immune complexes in sera from individuals with strongyloidiasis and discriminate them from sera of individuals with other parasitic diseases and healthy individuals. Besides de conventional ELISA, the novel approaches can also be promptly applied as auxiliary diagnostic tools to the existing parasitological method for accurate diagnosis of human strongyloidiasis.     

Strongyloides stercoralis infection as a cause of acute granulomatous appendicitis in an HIV-positive patient in Athens,Greece

A case of acute granulomatous appendicitis due to Strongyloides stercoralis infection in an HIV-positive patient is described. To our knowledge this is the first case presented in the literature.     

A case of Strongyloides stercoralis and mesenteric tuberculous infection with acute abdominal pain in an HIV-positive patient

We describe an HIV-positive female patient who had acute abdominal pain as the initial presentation of Strongyloides stercoralis infection. The diagnosis was established by identifying rhabditiform larvae in stool. She also had intra-abdominal tuberculosis without intestinal perforation. To our knowledge, this is the first reported case of such a presentation.     

Epidemiological aspects of Strongyloides stercoralis infection in Okinawa, Japan.

The epidemiology of Strongyloides stercoralis infection was compared among three localities with various prevalences of human T lymphotropic virus type 1 (HTLV-1) infection in Okinawa Prefecture, Japan, using agar-plate culture of faeces. The prevalence of S. stercoralis infection is much higher in Gusukube, where HTLV-1 infection is rare, than in Yomitan, where this viral infection is common. In all localities the parasite prevalence is significantly higher in males than in females, whereas the prevalence of HTLV-1 infection is much higher in females. These epidemiological facts suggest that infection by S. stercoralis occurs independently of that by HTLV-1.     

Strongyloides stercoralis infection in an HIV positive patient--a case report from RIMS, Imphal, Manipur

Strongyloides stercoralis, a nematode parasite in human with free living and autoinfective cycles, is often an asymptomatic infection of the upper small intestine. If the host becomes immunocompromised, autoinfection may increase the intestinal worm burden and lead to disseminated strongyloidiasis. We report a case of a 33 year old male HIV positive patient admitted on 2/6/08 in male medical ward, Regional Institute of Medical Sciences, Imphal, Manipur with complaints of loose stools, pain abdomen, nausea, vomiting, generalized weakness, loss of appetite and loss of weight for past one month with fever off and on. Stool examination reveals larvae of Strongyloides stercoralis. The patient was successfully treated with Ivermectin 200 microgm/kg daily for 2 days.     

Biliary obstruction resulting from Strongyloides stercoralis infection. Report of a case.

Hepatobiliary manifestations of strongyloidiasis are rare. A case is described of biliary obstruction associated with the presence of Strongyloides stercoralis in the duodenal mucosa and 250 microns rhabditiform larvae in bile. Biliary obstruction resulted from papillary stenosis, which resolved after treatment with thiabendazole. It is proposed that papillary stenosis may be responsible for obstructive jaundice associated with Strongyloides stercoralis infection, and that strongyloidiasis should be added to the causes of papillary stenosis.     

Prominence of IgG4 antibodies in the human responses to Strongyloides stercoralis infection

The participation of the four subclasses of IgG in the humoral response to Strongyloides stercoralis was assessed by analyzing total and parasite-specific responses of each IgG subclass in 20 patients with uncomplicated strongyloidiasis and 21 immunocompromised patients with extraintestinal disease. The total component of each subclass was normal in most patients. IgG4 antibodies (measured by ELISA) were the most prominent parasite-specific response in both groups. Specific IgG2 and IgG4 responses were significantly more elevated in immunocompetent than in immunosuppressed patients. When the reactivity of each IgG subclass was analyzed by immunoblotting on SDS-PAGE-separated larval antigens, IgG4 recognized more antigens than did any other subclass. No parasite antigens were selectively recognized by either clinical group. Thus the continuous antigenic stimulation of chronic strongyloidiasis may result in an enhanced IgG4 subclass response. However, no presence or absence of humoral responses specific for filariform larval antigens was associated with the extraintestinal dissemination of the parasite.     

Immunity to a challenge infection of Strongyloides stercoralis third-stage larvae in the jird

Jirds support the entire life-cycle of Strongyloides stercoralis. We therefore used this host as a model to define the mechanism of the immune response to a challenge infection, as well as the parasite stage effected by the response. Jirds given a primary infection of S. stercoralis are resistant to re-infection. The use of implanted diffusion chambers containing larvae showed that the immune response killed the third-stage larvae, and this was confirmed by subcutaneous infections. The larvae of a challenge infection are killed within 48 h, a time period too short to allow for the development of L4 and adult worms. The immune response is dependent on both a serum factor and cells, suggestive of an ADCC type response.     

Prevalence of HPV infection among Greek women attending a gynecological outpatient clinic

Background  

Human papillomavirus (HPV) infection is a causative factor for cervical cancer. Early detection of high risk HPV types might help to identify women at high risk of cervical cancer. The aim of the present study was to examine the HPV prevalence and distribution in cervical smears in a sample of Greek women attending a gynecological outpatient clinic and to explore the determinants of the infection.     

Prevalence and epidemiological significance ofTrypanosoma cruzi infection among latin american immigrants in Berlin, Germany

Summary A survey was conducted among Latin American immigrants living in Berlin to investigate the presence ofTrypanosoma cruzi infection and to evaluate possible risk factors. One hundred persons were interviewed about risk factors (rural origin, contact with the reduviid bug) and evaluated serologically. The sera were tested with indirect immunofluorescence (IIF). All samples seroreactive with IIF were additionally evaluated with an ELISA forT. cruzi antibodies. To rule out cross-reactivity all seroreactive sera were tested with IIF forLeishmania infantum antibodies. Two persons were seroreactive in IIF and ELISA and three were seroreactive in the IIF only. The overall seroprevalence according to WHO criteria was therefore 2% (2/100). All samples were negative forLeishmania antibodies. Only one of the seropositive persons showed a risk factor forT. cruzi infection in their medical history. These findings suggest that routine serologic testing of Latin Americans is indicated to reduce the risk of transmission by blood transfusion and congenital transmission.     

Host-finding behavior of Strongyloides stercoralis infective larvae to sodium cation, human serum, and sweat

The host-finding behavior of Strongyloides stercoralis infective larvae was examined by in vitro agarose assay method. As human body fluid contains 0.85% (ca 0.15 molar) NaCl, various concentrations of sodium chloride, from 0.5M to 0.01M (7 steps), were examined. Many larvae were attracted at concentrations between 0.5 and 0.05M of sodium chloride. The concentration of 0.05M attracted the most larvae. The concentration of 0.02M of sodium chloride showed greatly reduced larval attraction compared with 0.05M. Therefore, the threshold concentration was determined as 0.05M. Then, 0.05M of chemicals were examined in a further experiment. Chloride compounds (NaCl, KCl, CaCl2, MgCl2) were investigated. These chemicals are components of human body fluids. Distilled water was used as the control in all experiments. Only sodium chloride attracted the larvae. Next, alkaline compounds were examined [NaOH, KOH, Ca(OH)2, and Mg(OH)2]. Larvae accumulated only at the NaOH site. The results suggested that the Na cation is important for larval attraction. A high pH value did not influence attraction at all. Next, human serum was tested. The human serum used was from normal serum to 1:32 diluted sera by distilled water (7 steps). Hierarchical attraction was seen according to serum concentration. Next, human sweat was collected from a limited zone of chest skin where only eccrine glands were distributed. Non-diluted sweat attracted the most larvae. Sweat might act as one of the most probable factors for infection by this skin-penetrating nematode.     

Prevalence of human immunodeficiency virus infection among patients attending tuberculosis clinics in the United States.

In 1988-1989, surveillance for human immunodeficiency virus (HIV) infection was conducted in 20 clinics providing medical care for patients with suspected and confirmed tuberculosis (TB) in 14 cities. A total of 3077 specimens from consecutive patients were tested for HIV after patient identifiers were removed. The median clinic seroprevalence rate was 3.4%, (range, 0-46.3%). The highest rates were found in the Northeast and Atlantic coastal areas. Rates by clinic were highest for persons born in the United States (median, 11.2%) and in the Caribbean region (Haitians, 36%-40%, and Cubans, 16%). Most HIV-infected patients had pulmonary TB, but HIV infections were more frequent in patients with extrapulmonary TB than in pulmonary TB patients (19.8% vs. 10.2%, P less than .0002). For US-born patients, rates did not differ by race or sex. These serosurveillance data indicate widespread HIV infection among TB patients and have important implications for clinical management of TB patients and for TB and AIDS prevention programs. Testing all HIV-infected persons and all TB patients for dual infection is essential to control the interrelated epidemics of AIDS and TB.     

High prevalence of Strongyloides stercoralis among farm workers on the Mediterranean coast of Spain: analysis of the predictive factors of infection in developed countries

Strongyloidiasis is a parasitosis characterized by persistent infection before dissemination and the development of potentially fatal disease. Since diagnosis is difficult, knowledge of the prevalence and geographic distribution of the disease is of practical importance. A study was made of Strongyloides stercoralis infection in a random and representative sample of farm workers in a tourist region in Spain based on the detection of larvae of triple stool samples. The prevalence of infection was 12.4% (95% confidence interval [CI] = 8.4-16.4). None of the 26 clinical or epidemiologic variables analyzed were found to be predictive of infection. Only eosinophilia (> 400 eosinophils/mm3) was significantly greater among the infected individuals (odds ratio = 73.4, 95% CI = 16.3-327.0), with a sensitivity of 93.5% and a specificity of 93.1%. A screening program is proposed to detect eosinophilia, to provide treatment without stool examinations, and thus afford a cost-effective policy for preventing the development of severe forms of the disease among specific risk groups where the prevalence of other parasitoses is low.     

The sociodemographic profile, risk categories and prevalence of HIV infection among people attending a London same-day testing clinic, 2000-2001

The objectives were to determine the sociodemographic profile, risk category, and prevalence of HIV infection amongst people attending a confidential clinic providing counselling, medical advice and results of HIV antibody testing on the same day of consultation. Data were collected on all 1749 individuals attending the same-day HIV testing clinic at the Royal Free Hospital, London and proceeding to HIV testing between June 2000 and May 2001. One thousand, one hundred and forty-eight men and 601 women (mean age 33.3 years) were tested for HIV antibodies. The primary risk for HIV infection was heterosexual contact (69.9%; 1224/1749) and homosexual contact (27.7%; 485/1749). Fifty individuals tested HIV-positive (42 men and eight women). HIV seroprevalence was 2.8% (50/1749) and was highest among men who reported risk through homosexual contact (6.2%; 30/485). The rates for heterosexual men and women were 1.8% (12/648) and 1.4% (8/576), respectively, though they were highest among Black Caribbean (12%; 3/25) and Black African attendees from sub-Saharan African countries (11.2%; 18/160). Of the total number attending the clinic, more than half (56%; 981/1749) had previously been tested and received a negative test result. Of the fifty HIV antibody-positive individuals, 26%, (13) had previously received a negative result and had all reported risk through homosexual contact. Thirty of the HIV antibody-positive individuals were asymptomatic, 14 were symptomatic and three were diagnosed with an AIDS-defining condition. Half of all HIV-positive attendees (51.2%; 22/43) presented at the time of testing with CD4 cell counts below the normal range (>400x10(6)/l). The high HIV seroprevalence among homosexual men, some of whom had previously tested negative, suggests that HIV prevention strategies used within this group may need to be reassessed. The continuing high HIV seroprevalence among individuals from African countries suggests that this population require specific targeting for HIV risk reduction and information on the advantages of early diagnosis and treatment.     

Prevalence of malaria among patients attending public health facilities in Maputo City, Mozambique

We conducted a health facility-based survey to estimate the prevalence of malaria among febrile patients at health facilities (HFs) in Maputo City. Patients answered a questionnaire on malaria risk factors and underwent malaria testing. A malaria case was defined as a positive result for malaria by microscopy in a patient with fever or history of fever in the previous 24 hours. Among 706 patients with complete information, 111 (15.7%) cases were identified: 105 were positive for Plasmodium falciparum only, two for Plasmodium ovale only, and four for both P. falciparum and P. ovale. Fever documented at study enrollment, age ≥ 5 years, rural HF, and travel outside Maputo City were statistically significantly associated with malaria by multivariate analysis. We found a high prevalence of laboratory-confirmed malaria among febrile patients in Maputo City. Further studies are needed to relate these findings with mosquito density to better support malaria prevention and control.