Cellular responses and cytokine profiles in Ascaris lumbricoides and Trichuris trichiura infected patients

The impact of intestinal helminth infection, i.e. Ascaris lumbricoides and Trichuris trichiura, on cellular responsiveness and cytokine production was investigated in young adults. Ascaris-specific cellular responsiveness was higher in parasite-free endemic controls than in patients infected with T. trichiura, or A. lumbricoides, or patients co-infected with both parasites. Also, mitogen-induced tumour necrosis factor (TNF)-alpha, interleukin (IL)-12 and interferon (IFN)-gamma secretion by peripheral blood mononuclear cells (PBMC) was higher in negative endemic controls than in infected individuals. Ascaris antigen-specific production of TNF-alpha, IL-12 and IFN-gamma was low in singly Ascaris as well as in co-infected patients, whereas secretion of IL-10 and IL-13 was elevated and similarly high in all patient groups. The detection of Trichuris-specific and Ascaris-specific IgG4 revealed significantly higher serum antibody levels in Trichuris or Ascaris patients when compared to endemic controls (P < 0.05), whereas parasite-specific IgE antibody levels were similarly high in infected individuals and in endemic controls. In summary, chronically infected Ascaris and Trichuris patients with a high parasite load presented reduced cellular reactivity and lower type 1 TNF-alpha, IFN-gamma and IL-12 responses when compared with endemic controls, whereas type 2 IL-10 and IL-13 productions were similar in all groups from the endemic area. The former may support parasite persistence, whereas substantial type 2 cytokine release may promote protective immunity, suggesting an adaptation of the host to control the parasite burden while minimizing immune-mediated host self-damage.     

Albendazole and infections with Trichuris trichiura and Giardia intestinalis

One hundred and twenty-eight children aged 4 to 11 years old in Dhaka, Bangladesh were treated for infections with Trichuris trichiura and other intestinal parasites using a single dose of 400 mg of albendazole. Only one Trichuris infection was apparently cured although egg counts fell by about 50%. A larger single dosage is recommended to treat Trichuris. Eleven out of 46 infections with Giardia intestinalis were not detected after treatment (p less than 0.001).     

Detection of upper gastrointestinal blood with fecal occult blood tests

OBJECTIVE: Although fecal occult blood (FOB) tests have most often been used to detect occult bleeding from the lower gastrointestinal (GI) tract, their utility in detecting occult blood loss from the upper GI tract is less well understood. The aims of this study were to determine whether small amounts of blood from the upper GI tract can be detected by currently available FOB tests and, if so, to correlate FOB tests with semiquantitative GI blood. METHODS: Groups of 10 healthy volunteers without a history of GI disease drank 5, 10, or 20 ml of their own blood mixed with tomato juice for 5 or 3 consecutive days. Standard dietary and medication restrictions were observed. Consecutive stools were tested for 2 days before, as well as 4 days after, blood ingestion. Each stool was simultaneously tested for FOB with HemoQuant (HQ), Hemoccult II (HO II), Hemoccult II SENSA (SENSA), HemeSelect (HS), and FlexSure OBT (FS). RESULTS: The mean age and hemoglobin concentration of the study population were 29.3+/-0.5 yr and 14.3+/-0.3 g/dl, respectively. No subject noted GI symptoms during blood ingestion. Fecal blood levels (measured by HQ) were elevated within 2 days after initiation of blood ingestion and remained elevated until 2-3 days after cessation of blood ingestion. Mean fecal blood levels peaked at 2.1, 7.9, 8.0, and 13.5 (mg hemoglobin/g stool) in groups ingesting 5 ml/5 days, 10 ml/3 days, 10 ml/5 days, and 20 ml/3 days, respectively. The proportion of positive tests during and immediately after the period of blood ingestion was greatest in the 20 ml/3 day group; 16% of HO II samples were positive as were 64% of SENSA and 67% of HQ samples. SENSA was more sensitive than HO II in all blood ingestion groups. At least one positive SENSA test was present in 50% of subjects ingesting 10 ml of blood (each 3 and 5 day groups) and in all subjects ingesting 20 ml/day. Immunochemical tests did not detect upper GI blood in any blood ingestion group. CONCLUSION: Inasmuch as many upper GI tract lesions have been reported to bleed small quantities of blood such as that studied here, and this amount of blood is readily detected with widely used guaiac-based FOB tests including Hemoccult II SENSA, the data emphasize that caution is warranted before attributing positive guaiac tests only to sites in the lower GI tract. The data raise the possibility that a combination of a highly sensitive guaiac-based FOB test plus an immunochemical could help differentiate occult upper from lower GI bleeding.     

Treatment with a single dose of albendazole improves growth of Kenyan schoolchildren with hookworm, Trichuris trichiura, and Ascaris lumbricoides infections

We studied the growth of primary schoolchildren with hookworm (87%), T. trichiura (97%), and A. lumbricoides (49%) who received a single 400 mg dose of albendazole or an identical placebo. Children were allocated at random to placebo (PL, n = 72) or albendazole (A, n = 78) groups, treated, and re-examined 6 months later. The A group gained significantly more than the PL group in weight (1.3 kg), percent weight for age (4.5% age points), percent height for age (0.5% age points), percent weight for height (4.3% age points), percent arm circumference (2.9% age points), and in triceps and subscapular skinfold thicknesses (1.2 mm). The PL group showed significant decreases between exams in percent weight for age, percent height for age, percent weight for height, percent arm circumference for age, and skinfold thicknesses for age. The A group had highly significant increases (P less than 0.0002) in all of these parameters except height for age. From Exam 1 to 2, the A group exhibited decreases (P less than 0.0002) in geometric means eggs per gram of feces (epg): for hookworm, means = 1,183 epg at Exam 1 vs. 136 epg at Exam 2 (67% egg reduction); for T. trichiura, means = 2,857 epg at Exam 1 vs. 1,061 epg at Exam 2 (28% egg reduction); and for A. lumbricoides, means = 86 epg at Exam 1 vs. 2 epg at Exam 2 (91% egg reduction). The PL group had a borderline increase in geometric means hookworm egg count, no significant change in T. trichiura egg count, and a small but significant decrease in A. lumbricoides egg count. Decreases in intensities of all infections were significant predictors of growth improvement. Hookworm egg count entered the equations for all 6 measurements, and A. lumbricoides and T. trichiura entered 4/6 equations. Single dose treatment with albendazole, despite continual exposure to infection, can permit improved growth rates in areas where intestinal helminths and protein-energy malnutrition are highly prevalent.     

Humoral immune responses in human infection with the whipworm Trichuris trichiura

The humoral immune response to infection with Trichuris trichirua was investigated by ELISA and immunoblotting using human sera from the Caribbean island of St Lucia. Immunoblot analysis of the degree of cross-reactivity with the related trichuroid Trichinella spiralis and with the other commonly co-existent nematodes, Ascaris lumbricoides and Toxocara canis, was carried out using selected sera. The IgM, IgA, IgE, and IgG subclass antibody levels were measured in ELISA using a detergent solubilized extract of adult T. trichiura. The IgG and IgE responses were highly Trichuris specific. Anti-T. trichiura IgM responses were totally cross-reactive with A. lumbricoides and were completely ablated by pre-incubation of sera with Ascaris antigen. The IgG response was predominantly of the IgG1 subclass with a minimal IgG3 response. Only 1 person out of 130 tested had a detectable IgG3 response. The IgG2 response appeared to be directed primarily against carbohydrate or polysaccharide antigens as pre-treatment of the ELISA plates with poly-L-lysine was necessary before a response could be detected. These data are the first demonstration of human isotypic responses to infection with T. trichiura.     

免疫法与化学法粪便潜血试验在结肠癌筛查中价值的荟萃分析

目的系统性评价免疫法粪便潜血试验(immunochemical fecal occult blood tests,iFOBT)与愈创木脂化学法粪便潜血试验(guaiac-based fecal occult blood tests,gFOBT)相比,是否能获得更高的筛检进展期结直肠肿瘤的临床应用价值。方法利用中英文检索词检索相关电子数据库,纳入直接比较iFOBT与gFOBT筛查结直肠肿瘤的随机临床试验,并提取其特征信息。根据QUADAS质量评价标准评价纳入文献的质量,荟萃分析各项研究中不同潜血试验方法对结直肠肿瘤的检出率和患者的依从性,计算相应的OR值和95%可信区间。通过漏斗图肉眼观察是否存在发表偏倚,并做Egger检验进一步验证。结果共5项随机临床试验(共22 709例)符合纳入标准。iFOBT与gFOBT对于结直肠癌及进展期腺瘤的检出率分别为2.23%和1.24%,合并OR值为1.50(95%CI:0.94~2.39)。而这种优越性主要体现在iFOBT与传统的化学法HemoccultⅡ相比时(OR=2.12,95%CI:1.66~2.71)。患者对于iFOBT和gFOBT的依从性分别为52.66%和43.93%,合并OR值为1.40(95%CI:1.16~1.68)。结论与传统gFOBT相比,iFOBT能够提高结直肠肿瘤筛检的准确性及患者的依从性。