Associations of IL13 gene polymorphisms and immune factors with Schistosoma haematobium infection in schoolchildren in four schistosomiasis-endemic communities in Ghana

BACKGROUND

Schistosomiasis remains a major public health issue with over 90% of the prevalence rates recorded in Sub-Saharan Africa. In this study, the relationships between different interleukin gene polymorphisms (IL-13-591A/G, IL-13-1055C/T, IL-13-1258A/G) and Schistosoma haematobium infection levels were evaluated; as well as the host plasma antibodies and cytokine profiles associated with schistosomiasis infection.

METHODOLOGY

A total of 469 school children aged 6 to 19 years from four schistosomiasis-endemic communities in Ghana were involved. Single urine and stool samples were obtained from each pupil, processed via sedimentation and Kato-Katz, and examined via microscopy for Schistosoma and soil-transmitted helminth (STH) eggs. Next, venous blood samples were drawn from 350 healthy pupils, and used to measure antibody and plasma cytokine levels by ELISA. Single nucleotide polymorphisms in the IL-13 gene were genotyped on 71 selected blood samples using the Mass Array technique.

PRINCIPAL FINDINGS AND CONCLUSION

The overall prevalence of urinary schistosomiasis was 21.11%. Community-level prevalences were 17.12%, 32.11%, 20.80%, and 15.32% for Asempaneye, Barikumah, Eyan Akotoguah, and Apewosika respectively. Generally, higher S. haematobium infection prevalence and intensity were recorded for participants with genotypes bearing the IL13-1055C allele, the IL13-591A, and the IL13-1258A alleles. Also, higher S. haematobium infection prevalence was observed among participants in the 12-14-year age group with the IL13-1055C, IL13-591A, and IL13-1258A alleles. Interestingly, higher STH prevalence was also observed among participants with the IL13-1055C, IL13-591A, and IL13-1258A alleles. Furthermore, the age-associated trends of measured antibodies and cytokines of S. haematobium-infected school-children depicted a more pro-inflammatory immune profile for pupils aged up to 1l years, and an increasingly anti-inflammatory profile for pupils aged 12 years and above. This work provides insight into the influence of IL-13 gene polymorphisms on S. haematobium, and STH infections, in school-aged children (SAC).

Pathogenetic factors of acute schistosomiasis mansoni: correlation of worm burden, IgE, blood eosinophilia and intensity of clinical manifestations

A clinical study of 34 previously healthy young patients simultaneously infected in an endemic area of schistosomiasis mansoni is presented, emphasizing the initial phase of the infection. Its intensity was established according to the occurrence, intensity, and duration of the signs and symptoms in order to investigate the possible correlations between the worm burden (estimated by the number of eggs in faeces), the blood eosinophilia and specific levels of IgE (estimated by the area of immediate intradermal reaction), with the clinical manifestations. A significant but low-level association was found between the worm burden and morbidity, suggesting that multiple factors, besides worm burden itself, may contribute to the pathogenesis of the disease.

Secondary cutaneous manifestations of acute schistosomiasis mansoni

The secondary cutaneous manifestations of the initial phase of schistosomiasis mansoni were studied in 34 patients who had been infected simultaneously in the same location. Sixteen of the patients developed angioedema and/or urticaria, generally of short duration and of mild intensity and usually about 30 days post-infection. There was no apparent association between the occurrence of these skin manifestations and the patients' worm burdens, blood eosinophilias or areas of immediate reaction to an intradermal inoculation with worm antigen. Other factors, particularly host immunological reactivity, are thought to be important elements in the genesis of the manifestations.

Pulmonary manifestations in the initial phase of schistosomiasis mansoni

The clinical and radiological pulmonary manifestations in the initial phase of schistosomiasis mansoni were studied in thirty previously healthy individuals who were simultaneously infected. The findings were compared with those concerning a control group and related to possible pathogenetic factors. The respiratory manifestations were of light or of moderate intensity, the dry cough being the most common symptom. The significant radiological alterations were: thickening of bronchial walls and beaded micronodulation, predominantly localized in the lower pulmonary fields. It was observed significant association between wheezing and IgE levels, estimated by the area of immediate intradermal reaction, as well as between the number of blood eosinophils and the occurrence of radiological changes. Moreover, there was correlation between the worm burden and the presence of wheezing, thoracic pain and beaded micronodulation. Thus, the clinical and radiological pulmonary manifestations described are significant part of the initial phase of schistosomiasis mansoni and present the worm burden, eosinophilia and levels of IgE as probable pathogenetic factors.

Egg excretion in the initial phase of experimental murine schistosomiasis mansoni: stability and association with worm burden

Stability of faecal egg excretion and correlation with results related to worm burden at the initial phase of schistosomiasis mansoni were observed in two groups of mice infected with different Schistosoma mansoni cercarial burdens, by means of analysis of quantitative parasitological studies and schistosome counts after perfusion. Thus, it may be stated that few quantitative parasitological stool examinations could be sufficient to express the infection intensity at the initial phase, on the same grounds that it was already demonstrated at the chronic phase. Furthermore, it is confirmed that the use of the number of eggs passed in the faeces as a tool to estimate the worm burden at the initial phase of schistosome infection is adequate.

Gastro-intestinal manifestations of the initial phase of schistosomiasis mansoni

Clinical gastro-intestinal manifestations were studied in 34 patients in the initial phase of schistosomiasis mansoni. The patients, all men, were of similar age and in similar nutritional condition and had been infected simultaneously at the same transmission site. Most (85%) showed some gastro-intestinal sign or symptom, generally of light or moderate intensity; 56% had liquid or pasty diarrhoea, 41% abdominal pain, 29% hepatomegaly, 21% dysentery, 15% anorexia, 12% pain on colon palpation and 9% nausea and/or vomiting. High worm burden was associated with blood in faeces but apparently not with any other clinical manifestation. There was no apparent association between any clinical manifestation and peripheral-blood eosinophil counts or titres of IgE specific for Schistosoma mansoni (evaluated by the area of immediate intradermal reaction to injected adult worm antigen). The absence of association between worm burden and nearly all the clinical gastro-intestinal manifestations strengthens the concept that factors other than worm burden, such as host reactivity, constitute important pathogenetic elements in the initial phase of schistosomiasis mansoni.

Characterization of the non-apparent clinical form in the initial phase of schistosomiasis mansoni

In this paper the history of 115 recruits that had bathed simultaneously in streams contaminated with Schistosoma mansoni, during military maneuvers, is reported. Thirty four of the infected patients presented the initial phase of the infection diagnosed through epidemiologic, clinical and laboratory parameters. Three out of the 34 patients did not reveal the clinical picture of the infection, thus being considered representatives of the non-apparent form of the disease. Differences between the intensity of blood eosinophilia, the area of immediate cutaneous reaction and the number of Schistosoma eggs eliminated in the stools proved not to be statistically significant (p > 0.05) when the non-apparent and acute cases of schistosomiasis were compared. These cases actually may be considered evidences of the non-apparent form hitherto merely taken for granted in the literature.

Effect of surgical removal of hydatid cyst on echinococcus-specific and polyclonal IgE antibodies: An aid for postoperative follow-up studies

To evaluate the significance of IgE antibodies in postoperative follow-up studies of patients with primary hydatidosis, 24 patients with detectable levels of Enchinococcus granulosus-specific IgE as determined by radioallergosorbent test (RAST) were re-examined one month and four months after surgical resection of the cyst. Serum levels of polyclonl IgE as determined by paper radiommunosorbent test (PRIST) were also determined before and after surgery. Anti-Enchinococcus IgE was undetected in 75% and 89% of patients with hepatic or pulmonary hydatidosis, respectively, four months after surgery. In addition, significant decline was observed in the serum polyclonal IgE four months after surgical removal of the cyst in both hepatic and pulmonary hydatidosis. However, surgical removal of pulmoary cyst alone showed no such effect on either polyclonal or Enchinococcus-specific IgE in hepatopulmonary hydatidosis. The results suggest that determination of specific an polyclonal IgE antibodies provide useful serological tests for prognosis and early detection of persistence and recurrence of hydatid disease postoperatively.

Antibody responses in schistosomiasis haematobium in Somalia. Relation to age and infection intensity

Antibody responses in schistosomiasis haematobium were studied in relation to age and infection intensity in Somalia. The area is highly endemic for Schistosoma haematobium but free of S. mansoni. Antibodies of the IgG class against particulate antigens of S. mansoni adult worms were investigated by immunofluorescence (gut and somatic associated antigens) and against soluble egg and adult worm antigens by ELISA. Total IgE levels were examined by Pharmacia IgE RIA, and specific IgE against soluble adult worm antigen by enzyme immunoassay. The IgG antibody response showed a characteristic pattern with highest reactivity against both gut associated and soluble egg antigens in the age group 10-14 years, when both prevalence and intensity of the infection were highest. Reactivity against somatic associated antigen was also high in this age group, but it increased slightly and remained at high level in the older ages. It is thought that such antigen is exposed mainly after the death of the parasite and that the antigenic stimulation may remain throughout most of the life of infected individuals. On the other hand, the IgG antibody reactivity against soluble adult worm antigen was low during childhood, but it increased significantly with age. It is suggested that repeated booster effects are needed for more potent response against these antigenic components. The finding of high levels of total IgE already in the youngest age groups, together with low specific IgE response, indicates that mainly other antigens are involved in the IgE production. The specific IgE response against soluble adult worm antigen was low but increased significantly with age.

Reactivity of IgE in human Schistosoma mansoni sera to S. mansoni antigens

Sera from Schistosoma mansoni-infected human patients were tested for total IgE levels and specific IgE and IgG antibodies to S. mansoni adult worm, cercaria, and egg antigen by ELISA. Of 50 sera, 28 were investigated by enzyme-linked crossed immunoelectrophoresis (ELCIE) to detect IgE reactivity to individual adult worm extract components. All sera showed increased total IgE levels. Specific IgE antibody levels to the different antigens varied; they were significantly correlated with each other but independent from total IgE. No correlation was found between specific IgG and any of the IgE antibody levels. Testing of the 28 individual sera by ELCIE revealed heterogeneous patterns. Seven sera were found to be nonreactive: three reacted with one precipitate, and the others reacted with between two and nine precipitates. However, in no case were identical patterns recognized, although four antigens reacted with about 80% of the sera. The number of bands detected by the individual sera depended neither on the levels of total IgE nor on those of specific IgE.

Antibodies of the IgE and IgG isotype, serum IgE and circulating immune complexes in schistosomiasis intercalatum

Individuals in an advanced phase of infection by Schistosoma intercalatum in whom viable ova are still present in the rectal mucosa but not excreted in detectable quantity, can be distinguished clinically from a younger group of individuals excreting S. intercalatum ova in their faeces. This clear-cut distinction is underlined by findings in parameters of humoral response. The ratio of anticercarial to anti-adult worm antibodies was higher in the group excreting eggs with probably more recent infection. Levels of total serum immunoglobulin were higher in this group, with the exception of serum IgA, which was lower as long as eggs were being excreted. In a later stage of the disease, relatively more IgG seems to be bound in circulating immune complexes. It is postulated that these stage specific patterns of humoral immune response represent the evolution of the host-parasite relationship during the infection.