Evaluation of Intussusception Following Pentavalent Rotavirus Vaccine (RotaTeq) Administration in 5 African Countries

BACKGROUND

A low-level risk of intussusception following rotavirus vaccination has been observed in some settings and may vary by vaccine type. We examined the association between RotaTeq vaccination and intussusception in low-income settings in a pooled analysis from 5 African countries that introduced RotaTeq into their national immunization program.

METHODS

Active surveillance was conducted at 20 hospitals to identify intussusception cases. A standard case report form was completed for each enrolled child, and vaccination status was determined by review of the child's vaccination card. The pseudo-likelihood adaptation of self-controlled case-series method was used to assess the association between RotaTeq administration and intussusception in the 1-7, 8-21, and 1-21 day periods after each vaccine dose in infants aged 28-245 days.

RESULTS

Data from 318 infants with confirmed rotavirus vaccination status were analyzed. No clustering of cases occurred in any of the risk windows after any of the vaccine doses. Compared with the background risk of naturally occurring intussusception, no increased risk was observed after dose 1 in the 1-7 day (relative incidence = 2.71; 95% confidence interval [CI] = 0.47-8.03) or the 8-21 day window (relative incidence = 0.77; 95%CI = 0.0-2.69). Similarly, no increased risk of intussusception was observed in any risk window after dose 2 or 3.

CONCLUSIONS

RotaTeq vaccination was not associated with increased risk of intussusception in this analysis from 5 African countries. This finding mirrors results from similar analyses with other rotavirus vaccines in low-income settings and highlights the need for vaccine-specific and setting-specific risk monitoring.

Acute intestinal intussusception among children under five years of age admitted in an Ouagadougou hospital, Burkina Faso, 2008-2013: epidemiological, clinical and therapeutic aspects

Introduction

acute intestinal intussusception is a life-threatening surgical condition. In some settings, rotavirus vaccines have been associated with a low-level increased risk of intussusception. We describe the epidemiology, clinical manifestations and management of intussusception in a tertiary referral hospital in Burkina Faso prior to the introduction of rotavirus vaccine in October 2013.

Methods

we retrospectively reviewed medical records of all children under 5 years of age treated at the Charles de Gaulle Pediatric Hospital for intussusception meeting the Brighton level 1 diagnostic criteria, from October 31st, 2008 to October 30th, 2013. We report the incidence of intussusception as well as descriptive characteristics of these cases.

Results

a total of 107 Brighton level 1 intussusception cases were identified, representing a hospital incidence of 21.4 cases / year. There were 69 males and 38 females (sex ratio of 1.8), with a median age of 8 months (range 2 months to 4 years). Sixty-two percent of intussusception cases occurred among infants (n = 67 cases). The average time from symptom onset to seeking medical consultation was 3.8 days +/- 2.7 (range 0 to 14 days). Treatment was mainly surgical (105 patients, 98.1%) with 35 patients (32.7%) undergoing intestinal resection. Thirty-seven patients (35.5%) experienced post-operative complications. The mortality rate was 9.3%. Intestinal resection was a risk factor for death from intussusception.

Conclusion

in this review of intussusception hospitalizations prior to rotavirus vaccine introduction in Burkina Faso, delays in seeking care were common and were associated with mortality.

[Tropical otitis]

A 68-year-old patient presents with chronic right-sided otorrhea associated with hypoacousis and chronic cough. Otoscopy showed multiple perforations of the right eardrum. The search of acid-fast bacilli was positive for direct examination of sputum and negative for the examination of ear pus. A antituberculosis treatment has been initiated.

[Members lymphedema in CNHU-HKM of Cotonou: Results of the rehabilitation treatment]

AIM

To report results of patients followed in physical medicine and rehabilitation (PMR) in CNHU-HKM of Cotonou.

PATIENTS AND METHODS

Retrospective, transversal study, aimed to be descriptive and analytical type. Were enrolled, 39 files of patients treated in PMR / CNHU-HKM, from 1st January 2014 to 31st December 2018, for unilateral lymphedema, who had done beginning and ending evaluations. Were excluded, venous, systemic or lipid edema. The severity and the result of the sessions were assessed taking into account the reports of perimeters of the member segments. Factors associated with the result were sought, by the Mann-Whitney test.

RESULTS

The localization of lymphedema was in thoracic and pelvic limbs, respectively in 64.1 and 35.9%. Were associated with the oedema functional difficulties (61.54%), muscle paresis (33.33%) and joint stiffness (30.77%). Patients benefited from 5 to 20 physiotherapy sessions. Has been associated with physiotherapy, the use of compression stockings (58.97%). The results have been satisfactory, mainly influenced by the development time.

CONCLUSION

Satisfactory results in the physiotherapy management of lymphedema have been noted in our context, especially in patients seen early.

Cost of pediatric hospitalizations in Burkina Faso: A cross-sectional study of children aged <5 years enrolled through an acute gastroenteritis surveillance program

INTRODUCTION

Diarrheal illness is a leading cause of hospitalizations among children <5 years. We estimated the costs of inpatient care for rotavirus and all-cause acute gastroenteritis (AGE) in two Burkina Faso hospitals.

METHODS

We conducted a cross-sectional study among children <5 years from December 2017 to June 2018 in one urban and one rural pediatric hospital. Costs were ascertained through caregiver interview and chart abstraction. Direct medical, non-medical, and indirect costs per child incurred are reported. Costs were stratified by rotavirus results.

RESULTS

211 children <5 years were included. AGE hospitalizations cost 161USD (IQR 117-239); 180USD (IQR 121-242) at the urban and 154USD (IQR 116-235) at the rural site. Direct medical costs were higher in the urban compared to the rural site (140USD (IQR 102-182) vs. 90USD (IQR 71-108), respectively). Direct non-medical costs were higher at the rural versus urban site (15USD (IQR 10, 15) vs. 11USD (IQR 5-20), respectively). Indirect costs were higher at the rural versus urban site (35USD (IQR 8-91) vs. 0USD (IQR 0-26), respectively). Rotavirus hospitalizations incurred less direct medical costs as compared to non-rotavirus hospitalizations at the rural site (79USD (IQR 64-103) vs. 95USD (IQR 80-118)). No other differences by rotavirus testing status were observed. The total median cost of a hospitalization incurred by households was 24USD (IQR 12-49) compared to 75USD for government (IQR 59-97). Direct medical costs for households were higher in the urban site (median 49USD (IQR 31-81) versus rural (median 14USD (IQR 8-25)). Households in the lowest wealth quintiles at the urban site expended 149% of their monthly income on the child's hospitalization, compared to 96% at the rural site.

CONCLUSIONS

AGE hospitalization costs differed between the urban and rural hospitals and were most burdensome to the lowest income households. Rotavirus positivity was not associated with greater household costs.

Impact and effectiveness of pentavalent rotavirus vaccine in children <5 years of age in Burkina Faso

BACKGROUND

Burkina Faso was one of the first African nations to introduce pentavalent rotavirus vaccine (RV5, RotaTeq) into its national immunization program in October 2013. We describe the impact and effectiveness of rotavirus vaccine on acute gastroenteritis (AGE) hospitalizations among Burkinabe children.

METHODS

Sentinel hospital-based surveillance for AGE was conducted at four hospitals during December 2013 - February 2017. Demographic, clinical, and vaccination information was collected and stool specimens were tested by EIA. Trends in rotavirus AGE hospitalizations and changes in the proportion of AGE hospitalizations due to rotavirus were examined at two sentinel sites from January 2014 - December 2016. Unconditional logistic regression models using data from all 4 surveillance sites were used to calculate vaccine effectiveness (VE, defined as 1-odds ratio) by comparing the odds of vaccination among rotavirus AGE (cases) and non-rotavirus AGE (controls) patients, controlling for age, season, hospital site and socioeconomic factors.

RESULTS

The proportion of AGE hospitalizations that tested positive for rotavirus declined significantly among children <5 years of age, from 36% (154/422) in 2014 to 22% (71/323, 40% reduction, p < .01) in 2015 and 20% (61/298, 44% reduction, p < .01) in 2016. Among infants, the percentage of AGE admissions due to rotavirus fell significantly from 38% (94/250) in 2014 to 21% (32/153, 44% reduction, p < .01) in 2015 and 17% (26/149, 54% reduction, p < .01) in 2016. The adjusted VE for full 3-dose series of RV5 against rotavirus hospitalization was 58% (95% [CI], 10%, 81%) in children 6-11 months of age and 19% (-78%, 63%) in children ≥12 months.

CONCLUSION

Rotavirus hospitalizations declined after introduction of pentavalent rotavirus vaccine in children, particularly among infants. RV5 significantly protected against severe rotavirus gastroenteritis in infants, but effectiveness decreased in older children.

Epidemiological and Clinical Aspects and Therapy of Chronic Otitis Media in the "ENT" and Cervicofacial Surgery Ward in the University Hospital of Ouagadougou

Objectives. The aim of this study was to analyze the epidemiological and clinical aspects of chronic otitis media and its therapeutic processes in our context. Patients and Methods. In a prospective study over a period of 1 year (March 2009-February 2010), 79 patients with chronic otitis media have been cared for in the otolaryngology ward of the University Hospital of Ouagadougou. Results. Chronic otitis media (COM) commonly occurs in the age group from 0 to 15 years (40.50%). Otorrhea was the main reason for consultation in 53 cases (67.10%); the most frequently encountered clinicopathological forms were simple COM (71%) followed by otitis media with effusion (24.30%). Intra-auricular instillations of traditional products (46.09%) were the dominant favoring factor. Treatment was essentially through medication in 59 cases with a stabilization of lesions. Endotemporal complications were noticed in 6 cases. Conclusion. The fight against chronic otitis media is carried out through preventive measures of education the of people.

Experience with head and neck missile injuries at the yalgado university teaching hospital, ouagadougou, burkina faso

BACKGROUND

To report the diagnostic and therapeutic options of missile head and neck injuries.

AIM AND OBJECTIVES

To present our experience in the management of head and neck missile injuries as seen in our centre.

METHODOLOGY

All the patients with head and neck missile injuries who were managed in the ENT and Dental services of Yalgado University Teaching Hospital, in Ouagadougou, the capital of Burkina Faso between January 2003 and December 2012 were reviewed. The data obtained from medical records included demographic data, history, physical findings, and site of injury, diagnosis, type of treatment/surgery, complications and outcome.

RESULTS

Out of a total of 32 patients in this study, there were 26 males and 6 females with a sex ratio of 4.3:1. Their ages ranged from 18 to 63 years with a mean of 32 years ± 5.2. The age range of 20-40 accounted for 68.7% of the patients. The injury was accidental in 37.5%, assault in 56.3 and self inflicted/suicide in 6.3%. Most (59.4%) of the patients had multiple injuries while in 50 % of the cases, the injuries affected the face. Surgical intervention was done in 59.4% of the patients and conservative treatment in 40.6 % of the patients. Complications were noted in 52% of the patients. Seven patients died given a mortality rate of 21.9%.

CONCLUSION

The head and neck missile injuries are not uncommon in our environment with a high mortality and morbidity rates.

Prognostic impact of weight loss in 1-year survivors after transthoracic esophagectomy for cancer

Malnutrition is common 1 year after esophageal cancer surgery. However, the prognostic impact of this malnutrition on long-term outcome has been poorly reported. This study aims at determining the potential effect on disease-free survival (DFS) of weight loss observed at 1 year in disease-free survivors after curative esophageal resection. From a prospective single-institution database, 304 patients having undergone a transthoracic esophagectomy with two-field lymphadenectomy and gastric reconstruction between 1996 to 2008 were identified. Patients who died during the postoperative course (n= 24), patients who died within the first postoperative year (n= 12), patients who presented with an early recurrence within the first postoperative year (n= 20), and those who were lost to follow-up (n= 22) were excluded from the study, as well as those for whom the follow-up was shorter than 1 year (n= 21). The remaining 205 patients constituted a homogeneous group of 1-year disease-free survivors after full postoperative work-up and formed the material of the present study. Body weight (BW) values were collected before any treatment at the onset of symptoms (initial BW) and 1 year after esophagectomy. A 1-year weight loss (1-YWL) exceeding 10% of the initial BW defined an important malnutrition. Impact of the 1-YWL ≥ or <10% of the initial BW on DFS was investigated. Logistic regression was performed to identify factors affecting DFS. The mean initial BW was 69.1 ± 12 kg, corresponding to a mean body mass index (BMI) of 23.8 ± 3 kg/m(2) . Preoperatively, 32 (15%) patients were in the underweight category (BMI < 20 kg/m2), 110 (54%) were in normal (BMI = 20-24 kg/m2), and 63 (31%) were in the overweight category (BMI ≥ 25 kg/m2). Mean 1-year BW was 63.5 ± 12 kg. 1-YWL was <10% of the initial BW in 92 patients (45%) and ≥ 10% in 113 patients (55%). Accordingly, 5-year DFS rates were 66% (median: 80 months) and 48% (median: 51 months), respectively (P= 0.005). On multivariate analysis, only three independent variables affected the DFS significantly: clinical N stage (cN) status (P= 0.007; odds ratio: 1.99, 1.2-3.3), incomplete resection (P= 0.008, OR: 3.6, 1.3-9.3), and 1-YWL ≥ 10% (P= 0.004, OR: 2.1: 1.2-3.4). 1-YWL of or exceeding 10% of the initial BW in 1-year disease-free survivors has a negative prognostic impact on DFS after esophagectomy for cancer. This information offers another view on the objectives of the perioperative nutritional care of these patients. Special vigilance program on the nutritional status in post-esophagectomy patients should be the rule.

[Prise en charge chirurgicale des goitres hyperthyroïdiens a Bamako]

GOAL

To assess the surgical therapy in goiter with hyperthyroidism in a surgical unit of CHU du Point-G.

PATIENTS AND METHODS

A retrospective study was conducted, concerning 131 patients having undergone a thyroidectomy for goiter with hyperthyroidism from January 1st 1998 to December 31st 2007.

RESULTS

The files of 131 patients were analysed. The average age of patients was 39.74 years, with 114 women and 17 men. The goiter in Basedow disease was the first indication for surgery in hyperthyroidism (48 cases; 36.6%) followed by toxic adenoma (39; 29.8% of the cases) and toxic multinodular goiter (38; 29% of cases). Ninety patients had a subtotal thyroidectomy (68.7% of cases). One total thyroidectomy (0.8%), 39 isthmolobectomies (29.7%) and one isthmectomy (0.8%) were carried out. Anatomohistology showed 67.1% of colloid benign tumours, and 8 cases of cancers (6.2% of the cases). Early postoperative follow ups were due to hemorrhage (2 cases; 1.5%) and 3 cases of dysphonia (2.5%). One patient died (0.8%). After six months, 3 cases of wound cheloide (2.5%), one case of dysphonia, and one case of hypothyroidism were noted. For 86 patients (71.1%) the postoperative follow up was simple.

CONCLUSION

Surgery remains a treatment of choice for hyperthyroidism goiter. Other options are too expensive or not available.

[Cervicofacial cellulitis in Ouagadougou, Burkina Faso: report of 26 cases]

Cervicofacial cellulitis is still observed in Burkina Faso and can be severe. The aim of this study was to review diagnostic and therapeutic challenges associated with management of cericofacial cellulitis in our region where medical facilities are poor. A retrospective study of patients treated between January 1999 and December 2008 was performed. A total of 26 cases of cervicofacial cellulites were compiled. All patients underwent broad spectrum antibiotherapy associated imidazols. Surgical treatment was performed in 60% of the cases. Early diagnosis and treatment is essential for favorable outcome.

[Bilharziasis and urinary lithiasis: a study of 23 cases at the Gabriel Toure Hospital]

AIMS

Describe the clinical and therapeutic aspects of urinary stone on bilharziosis in the teaching hospital Gabriel Toure.

METHOD

It was about a prospective study done from January 1st to December 31, 2007 on all patients presenting a urinary stone with history of bilharziosis treated in the service of urology at the teaching hospital Gabriel Toure. Lost patients during the study were not included.

RESULTS

We brought together 23 cases of urinary stone on history of urinary bilharziosis. The mean age of our patients was 31 years with extreme of 10 and 64 years. Sex-ratio was 22 for men. Renal colic was the most frequent motive of consultation (30.4%). Fiver has been detected in 56.5% of cases.Stone has a renal localisation in 10 patients (43.5%), ureteral in 9 patients (39.1%) and vesical in 4(17.4%). Urine analysis has found following germs: Schistosoma haematobium (4 cases), positive cocci gram (3 cases), Enterococcus faecalis (1 case) and negative cocci gram (1 case). Moderate renal insufficiency has been detected in 4 patients (17.4%). Treatment has been surgical in 21 patients(91.3%). Nephrolithotomy was done in 7 patients (33.3%), ureterolithotomy in 7 others, cystolithotomyin 3 patients (14.3%), nephrectomy in 2 patients (9.5%), uretero-vesical reimplantation in 2 others.

CONCLUSION

The assessment of bilharziosis may decrease the frequency and prevent numerous and disastrous complications of urinary bilharziosis.

[Epidemiology of anguillulosis among public school children in Abidjan, Cote d'Ivoire]

PURPOSE

Strongyloides stercoralis is a neglected soil-transmitted helminth species. In Cote d'Ivoire, as elsewhere, there is a lack of parasitologic and epidemiologic data pertaining to this parasite. The purpose of this study was to evaluate the prevalence and impact of sociodemographic factors on anguillulosis among public school children in Abidjan, Cote d'Ivoire.

METHODS

Testing for Strongyloides stercoralis was performed in a random sample of 411 children from 10 public primary schools in Abidjan. Detection methods included direct examination of stool smears, the Baermann test and helminth coproculture study.

RESULTS

The overall prevalence of anguillulosis was 2.7% (N=411) (IC95% = 1.34-4.73). The M/F sex-ratio was 1. No correlation was found between prevalence and sex (p = 0.12). Prevalence was higher among children who reported contact with swamps and rivers (respectively 80% and 7.9%) than those who did not report such contact (respectively 1.7% and 1.5%) (p <0.01).

CONCLUSION

Contact with swamps and rivers is correlated with an increase in anguillulosis prevalence. Avoiding these areas and proper sanitation could help to reduce the prevalence of anguillulosis in Abidjan.

Erythrocyte polymorphisms in five ethnic groups of Northern Côte d'Ivoire

Distribution of some erythrocyte polymorphisms was investigated in five Northern Côte d'Ivoire ethnic groups. For the ABO blood group system, the frequencies of alleles p, q and r were 0.119, 0.150 and 0.731, respectively, while the frequencies of alleles D and d of the Rh blood group system were 0.726 and 0.274, respectively. These values are consistent with published data, while the high incidence of HbAS genotype could result from microevolutionay trends acting on this relatively small population. No 27-bp Southeast Asian ovalocytosis gene deletion was found in the sample.

[Major sickle cell anaemia and hypoacusia: about 112 cases in Yopougon, Côte d'Ivoire]

The objective of this study is to evaluate the impact of major sickle cell anaemia on the auditory function of the patients. It was a prospective survey conducted in the university hospital of Yopougon (Republic of Côte d'Ivoire). The auditory function of 112 major sickle cell anaemia patients 5- to 40-five-years-old, was compared with 112 healthy controls. 17% (19/112) of major sickle cell anaemia patients presented hearing loss from 30 dB to 65 dB versus 4% of controls. The average age of deaf patients was 26-years-old (7 years to 40-years-old). The sex-ratio was 0,73. The SC form with 47% (9/19) of deafness was the form the most frequently found followed by form SS, 37% (7/19) and form S beta+ thalassaemia 16% (3/19). The form S beta 0 thalassaemia did not record deafness patients. However the form having shown the highest rate of attack was the form S beta+ thalassaemia with 25% (3/12) followed by form SC 21% (9/43) and form SS 14% (7/51) of deafness. Deafness was generally light 73, 7% of the cases and often bilateral (52.6% of the cases). The audiometric loss affected both extremes of the hearing range, but was more significant in lower tones (58% of cases). Higher tones represented 5% of the cases. It was often sensorineural hearing loss 58% of the cases. Mixed hearing loss represented 42% of the cases.

COL1A2 gene deletion polymorphism in an Italian and an Ivorian populations

The COL1A2 gene is one of the two genes encoding for the polypeptides of type I collagen, that represent the major constituent of skin, bone, tendons, ligaments, blood vessels, dentin, and many interstitial tissues. The COL1A2 gene deletion polymorphism has been considered as an informative anthropological marker for describing geographically distinct human populations. Aim of the present study was to investigate the genetic variability at COL1A2 locus in two populations, one belonging to Ouangolodougou (N = 133), a village placed in Northern Ivory Coast, and one belonging to Lecco (N = 70), a village placed in a Northern Italy region called Lombardy. For each sampled population no data are available in literature. We reported, for the first time, the presence of the deleted allele among Ivorians (0.06), confirming the low deletion frequency of this polymorphism found in Sub Saharan Africa by other authors. For Italians, frequency analysis of this gene polymorphism (0.28 for the deleted allele) did not show any significant level of differentiation with respect to other Italian and European populations.

[Recklinghausen disease and surgery: clinical case]

To bring it back a clinical case of neurofibromatosis of the type 1 (NF1) in service of general surgery complicated of bulky invalidating royal tumours. The 35 year old patient presented on all the body multiples small tumefactions but also of bulky heavy cervico-thoracic royal tumours, invalidating, deteriorating the body and psychic image. A surgical ablation and a cutaneous closing in a time were necessary. The results of this esthetic palliative surgery were very satisfactory. The surgery can be of a great contribution during the evolution of the NF1 especially when the lesions become invalidating.

[Epidemiologic study of bluetongue in sheep, cattle and different species of wild animals in the Ivory Coast]

Between 1992 and 1993, a serological survey was conducted in Côte d'Ivoire on 623 sera from sheep, 215 sera from cattle and 211 sera from wild herbivores. These sera were tested for bluetongue virus (BTV) antibodies using an agar gel immunodiffusion test. The purpose of this survey was twofold: to establish the incidence of bluetongue in the country, and to analyse the putative role of BTV in the reproductive pathology of sheep. Seroprevalence was 52 +/- 4% in sheep, 95 +/- 3% in cattle, and 56 +/- 7% in wild herbivores. The authors found antibodies against BTV in kob (Kobus kob Erxleben, 1777), common waterbuck (Kobus ellipsiprymnus Ogilby, 1833), roan antelope (Hippotragus equinus Desmarest, 1804), buffalo (Syncerus caffer Sparrman, 1779), hartebeest (Alcelaphus buselaphus Pallas, 1766) and elephant (Loxodonta africana Blumenbach, 1797). A significant difference was found in seroprevalence in sheep between the three areas covered by the survey. Antibody prevalence increased significantly with age in sheep and wild herbivores, and seroprevalence was higher in dams with a history of abortion. It can therefore be concluded that bluetongue is enzootic in Côte d'Ivoire.

Resistance to Schistosoma mansoni in humans: influence of the IgE/IgG4 balance and IgG2 in immunity to reinfection after chemotherapy

The hypothesis of an association between human resistance to reinfection by the parasite Schistosoma mansoni and anti-larval immunoglobulin isotypes was tested by logistic regression in the presence of the explicative variables water contact, age, and sex. Of the seven isotypes tested (IgM, IgG1, IgG2, IgG3, IgG4, IgA, and IgE), only IgE, IgG4, and IgG2 showed an association (positive for IgE and negative for IgG2 and IgG4) with resistance to reinfection after chemotherapy. The opposite effects of IgE and IgG4 were undissociable in the analysis, indicating that these isotypes probably antagonize each other in protection. The negative association of IgG2 with resistance is consistent with the view that anti-carbohydrate antibodies may facilitate reinfection. Finally, epidemiologic and immunologic studies support the view that there is a progressive but slow development of acquired immunity in children and adolescents.

Environmental, genetic and immunological factors in human resistance to Schistosoma mansoni

The design of programs for the control of endemies requires the knowledge of the principal factors that determine parasite transmission and infection levels in exposed populations. In the studies summarized in this article, the role of environmental and host specific factors in the infection by S. mansoni have been evaluated. It is shown that a limited number of factors actually influences infection intensity: water contacts, age, and sex were shown to account for 20 to 25% of infection variance, while 35 to 40% of it was accounted for by the effect of a major codominant gene. A remarkable fact is the important weighting (around 55% of the variance) of factors (the major gene and age) that influence human capacities of resistance. This observation strongly supports control measures aimed at increasing human resistance, such as vaccination. The effect of age on the development of resistance has now been observed in several studies on S. mansoni or S. haematobium. It is, therefore, a constant finding in schistosomiasis infections that resistance develops extremely slowly requiring a long period of exposure to the parasite and repeated infections. These studies provide strong incentives to increase efforts in the evaluation of the immune response of subjects living in endemic areas. Such evaluations are necessary to define vaccine and vaccination programs, and they are also urgently needed to evaluate the effects of chemotherapy on the development of immunity in children and adolescents, as well as on the persistence of protective immunity in adults. Immunological studies begin to provide a clearer picture of the role of acquired immunity in human protection against S. mansoni. It is increasingly clear that the slow development of resistance in children, as well as its alteration in certain age groups, are related to the maturation of parasite specific immunity and its alteration by specific immune factors. Thus, the development of resistance is associated with the maturation of IgE-dependent immunity, whereas blocking Ab may interfere in children and adolescents with the expression of full resistance. This finding raises the question as to whether a vaccine could include major allergens without triggering the well-known deleterious side effects associated with hypersensitivity reactions. The absence of such reactions in subjects with high parasite-specific IgE levels who are exposed to daily infections suggests that this may be feasible.