Human infection with Ascaris lumbricoides is associated with suppression of the interleukin-2 response to recombinant cholera toxin B subunit following vaccination with the live oral cholera vaccine CVD 103-HgR.
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To investigate the potential immunomodulatory effects of concurrent ascariasis on the cytokine response to a live oral vaccine, we measured cytokine responses to cholera toxin B subunit (CT-B) following vaccination with the live oral cholera vaccine CVD 103-HgR in Ascaris lumbricoides-infected subjects randomized in a double-blind study to receive two doses of either albendazole or placebo prior to vaccination and in a group of healthy U.S. controls. Postvaccination cytokine responses to CT-B were characterized by transient increases in the production of interleukin-2 (IL-2; P = 0.02) and gamma interferon (IFN-gamma; P = 0.001) in the three study groups combined; however, postvaccination increases in IFN-gamma were significant only in the albendazole-treated A. lumbricoides infection group (P = 0.008). Postvaccination levels of IL-2 were significantly greater in the albendazole-treated group compared with the placebo group (P = 0.03). No changes in levels of Th1 and Th2 cytokines in response to control ascaris antigens were observed over the same period. These findings indicate that vaccination with CVD 103-HgR is associated with a Th1 cytokine response (IL-2 and IFN-gamma) to CT-B, that infection with A. lumbricoides diminishes the magnitude of this response, and that albendazole treatment prior to vaccination was able to partially reverse the deficit in IL-2. The potential modulation of the immune response to oral vaccines by geohelminth parasites has important implications for the design of vaccination campaigns in geohelminth-endemic areas. (+info)
Estimating the number of helminthic infections in the Republic of Cameroon from data on infection prevalence in schoolchildren.
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INTRODUCTION: The prevalence of infection with helminths is markedly dependent on age, yet estimates of the total number of infections are typically based on data only from school-aged children. Such estimates, although useful for advocacy, provide inadequate information for planning control programmes and for quantifying the burden of disease. Using readily available data on the prevalence of infection in schoolchildren, the relation between the prevalence of infection in school-aged children and prevalence in the wider community can be adequately described using species-specific models. This paper explores the reliability of this approach to predict the prevalence infection in the community and provides a model for estimating the total number of people infected in the Republic of Cameroon. METHODS: Using data on the prevalence of helminthic infection in school-aged children in Cameroon, the prevalence of infection in pre-school children and adults was estimated from species-specific linear and logistic regression models developed previously. The model predictions were then used to estimate the number of people infected in each district in each age group in Cameroon. RESULTS: For Cameroon, if only the prevalence of infection in schoolchildren is used, the number of people infected with each helminthic species will be overestimated by up to 32% when compared with the estimates provided by the species-specific models. The calculation of confidence intervals supports the statistical reliability of the model since a narrow range of parameter estimates is evident. Furthermore, this work suggests that estimation of national prevalence of infection and the number infected will be enhanced if data are stratified by age; this model represents a useful planning tool for obtaining more accurate estimates. Estimates based on data aggregated from three geographical levels (district, regional, and national) show that summarizing prevalence data at the national level will result in biases of up to 19%. Such biases reflect differences in the geographical distribution for the prevalence of each species. DISCUSSION: Developing more accurate estimates requires a better understanding of the differences in the spatial heterogeneity of each species and also better methods of incorporating this information when making estimates. (+info)
Ultrasonographic appearance of Ascaris lumbricoides in the small bowel.
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Roundworm infestation, one of the most common helminthic diseases worldwide, is caused by Ascaris lumbricoides, one of the largest parasites that infests the human bowel. A lumbricoides is virtually universal at some stage of childhood in semitropical and tropical regions. This study describes our experience with the ultrasonographic appearance of intestinal ascariasis in 84 patients, 2.5 to 42 years of age, examined over 2 years beginning October 1997. The patients' conditions ranged from acute intestinal obstruction to no clinical features pertaining to obstruction. Ultrasonographic examination was performed with an Echocee power Doppler real-time unit with a variable-frequency 3.7-MHz convex, 7.5-MHz linear probe. In longitudinal section the Ascaris worm presented as a linear intraluminal mass with 3 or 4 linear echogenic interfaces; in the cross section, it was round, sometimes appearing as a "target" sign. Some worms also showed serpentine movements. Sonographic examination of the patients in the left lateral decubitus position after ingestion of water improved detection and visualization of the worms in some cases. It is concluded that A lumbricoides in the small bowel has a sonographic appearance that can be recognized by the wary observer. (+info)
Ascaris lumbricoides in the lacrimal passage.
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Ascariasis is caused by the roundworm, Ascaris lumbricoides. We report an additional case of live Ascaris lumbricoides removed from the lacrimal puncta of a 10-year-old boy. (+info)
Non-invasive management of Ascaris lumbricoides biliary tact migration: a prospective study in 69 patients from Ecuador.
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Ascariasis is one of the most common helminthic diseases. Its most feared complication is migration into the biliary tree. Some authors recommend immediate duodenoscopy in all cases of biliary migration, with sphincterotomy for the extraction of the parasites, and surgical extraction in case of intrahepatic ascariasis. We followed prospectively 69 patients with ultrasonographical evidence of migration. Initial treatment consisted of intravenous analgesics and antispasmodics, and albendazole 800 mg by mouth. Only patients with persisting symptoms or with high amylasaemia underwent duodenoscopy, with extraction in case of a visible worm. Surgery was limited to cases with persistent or progressive complications. In 97% of our cases the worms disappeared with noninvasive therapy alone. A duodenoscopy was done in 30 (42%) cases; in 10 (14%) a worm was found in the ampulla of Vater and extracted without sphincterotomy. In none of the 6 cases with A. lumbricoides in the intrahepatic biliary tree did the parasite persist. Only one patient required surgical intervention. Treatment of A. lumbricoides migration to the biliary tract should be principally medical. Duodenoscopy with extraction of a visible worm should be limited to cases with persisting pain and/or hyperamylasaemia. Invasive methods like sphincterotomy and surgery should be restricted to patients who do not respond to conservative treatment. (+info)
Prevalence and intensity of infections of Ascaris lumbricoides and Trichuris trichiura and associated socio-demographic variables in four rural Honduran communities.
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Between January and March 1998, a cross-sectional survey was carried out in four rural communities in Honduras, Central America. We examined the prevalence and intensity of Ascaris lumbricoides and Trichuris trichiura infections among 240 fecal specimens, and the association between selected socio-demographic variables and infection for 62 households. The overall prevalence of A. lumbricoides and T. trichiura was 45% (95% CI 39.0-51.9) and 38% (95% CI 31.8-44.4) respectively. The most intense infections for Ascaris and Trichuris were found in children aged 2-12 years old. By univariate analysis variables associated with infections of A. lumbricoides were: number of children 2-5 years old (p=0.001), level of formal education of respondents (p=0.01), reported site of defecation of children in households (p=0.02), households with children who had a recent history of diarrhea (p=0.002), and the location of households (p=0.03). Variables associated with both A. lumbricoides and T. trichiura infection included: number of children 6-14 years old (p=0.01, p=0.04, respectively), ownership of a latrine (p=0.04, p=0.03, respectively) and coinfection with either helminth (p=0.001, p=0.001, respectively). By multivariate analysis the number of children 2-5 years living in the household, (p=0.01, odds ratio (OR)=22.2), children with a recent history of diarrhea (p=0.0, OR=39.8), and infection of household members with T. trichiura (p=0.02, OR=16.0) were associated with A. lumbricoides infection. The number of children 6-14 years old in the household was associated with both A. lumbricoides and T. trichiura infection (p=0.04, p=0.01, OR=19.2, OR=5.2, respectively). (+info)
Clinical trial of mebendazole, a broad-spectrum anthelminthic.
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Eighty-five children aged 5-14 years who were infested with worms were treated with mebendazole 100 mg twice daily for three days. The percentage cure rates were ascaris 100%, trichuris 94%, hookworm 82%, and hymenolepis 39%. The drug was well tolerated and with its broad activity should be very useful in treating those with multiple infestations. (+info)
Reorganization of a nutrition unit in Papua New Guinea.
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Adequate nutrition is a medical priority. It has been estimated that more than half the children in the Chimbu District of Papua New Guinea are malnourished. A practical scheme combat poor nutrition there was based on emphasizing the value of breast-feeding and of locally grown foods. The daily menu given was the same, with three meals each day. The scheme's underlying principles can be adapted for any developing country or for migrant and other minority groups in a developed country. (+info)