Schistosomiasis: a critical review

Co-infections of Schistosoma spp. and Malaria with Hepatitis Viruses from Endemic Countries: A Systematic Review and Meta-Analysis

BACKGROUND

Co-infection of schistosomiasis and malaria with hepatitis B virus (HBV) and hepatitis C virus (HCV) are common in countries where schistosomiasis and malaria are endemic.

OBJECTIVE

The present systematic review and meta-analysis was conducted to assess the prevalence of malaria/hepatitis viruses and Schistosoma/hepatitis viruses' co-infections.

MATERIALS AND METHODS

Relevant published studies on the co-infection of malaria and Schistosoma spp. with HBV and HCV were retrieved via international databases (PubMed, Scopus, Web of Science, and Google Scholar). Regarding meta-analysis, the random-effect model was employed by forest plot with a 95% of confidence interval (CI).

RESULTS

A total of 22 studies, including 15 studies with malaria/hepatitis viruses' co-infection and 7 studies with Schistosoma/hepatitis viruses' co-infection met the eligibility criteria. The co-infection of malaria/HCV and malaria/HBV in different populations were 15% (95% CI, 0-77%) and 5% (95% CI, 1-10%), respectively. Moreover, Schistosoma/HCV and Schistosoma/HBV co infection were detected in 7% (95% CI, 0-54%) and 2% (95% CI, 0-7%), respectively.

CONCLUSION

The overlaps between Schistosoma spp. and malaria with hepatitis B and C viruses in endemic countries with lower income levels were high, which deserve further attention.

[Urogenital tuberculosis and schistosomiasis (bilharzia) : Urological challenges in displaced persons]

We are observing the largest worldwide wave of migration ever. Displaced persons usually do not have access to general health care and are faced with a lack of hygienic conditions and infection control while fleeing, which leads to an accumulation of "exotic" infectious diseases. The number of patients with tuberculosis (TB) had declined for many years in Germany; however, increasing numbers of cases have recently been observed. For urologists, of course, the manifestations of urogenital TB (UGTB) are of particular interest. Therefore, the basics regarding diagnosis and therapy of UGTB are discussed in this article and explained using case studies. The second important "exotic" infectious disease that urologists are increasingly facing is schistosomiasis. The larvae (found mostly in stagnant water) penetrate through intact human skin, mature and migrate into the liver, from where they immigrate into the venous capillaries of the intestine, the small pelvis, the bladder wall and the distal ureter, and there cause chronic inflammation. All urologists should be familiar with the diagnosis, therapy and prophylaxis of urogenital schistosomiasis and the oncogenesis of schistosomiasis-associated bladder carcinoma.

Therapeutic effect of Arctium lappa in Schistosoma haematobium associated kidney disturbance: biochemical and molecular effects

Schistosoma haematobium (S. haematobium) infection has been found to be strongly associated with bladder cancer, which necessitates for discover of a natural new therapeutic agent. The aim of this study was to evaluate the therapeutic effect of Arctium lappa seed extract in S. haematobium associated kidney disturbance. Forty male albino mice were used and divided into four equal groups; group 1 control includes non-infected healthy mice, groups 2, 3 and 4 subcutaneous infected with S. haematobium cercariae. Groups 3 co-treated daily with oral dose of A. lappa seed extract (300 mg/kg, bwt) for 15 days in the same time of S. haematobium infection. Groups 4 post-treated daily for 15 days with oral dose of A. lappa seed extract (300 mg/kg, bwt) after 15 days of S. haematobium infection. The results obtained revealed that S. haematobium significantly decreased kidney weight and serum sodium, potassium and chloride, but increased urinary volume, urinary excretion of sodium, potassium and chloride, serum urea, creatinine and uric acid. Schistosoma haematobium also significantly decreased kidney superoxide dismutase, glutathione peroxidase and reduced glutathione levels while increased kidney lipid peroxidation level. Co- and post-treatment with A. lappa seed extract restore all the above parameters to approach the normal values. These results were supported with histopathological examinations. In conclusion, A. lappa seed extract has therapeutic effect in kidney disturbance caused by S. haematobium where co-treatment of A. lappa seed extract was more effective than post-treatment of the extract.

Evaluation of sodium fluoride toxicity in Schistosoma infected snails: assessment of antioxidants, antiapoptotic, hypoprotein and hypocholesterol activities

The snails' tissues represents an intermediate or secondary host for Schistosoma sporocysts where, germ cells within the secondary sporocyst begin to divide to produce thousands of cercariae capable of infecting humans. The aim of the study was to evaluate the toxicity of sodium fluoride in Schistosoma snails' tissue homogenates. A total number of 264 different Schistosoma snails were collected from eight drainage water resources and divided into control uninfected and infected snails; where infected snails divided into four group; the first group without any treatment while second, third and fourth groups immersed in 25, 50 and 100 mg sodium fluoride/L during the period of 4 weeks then the snails' hemolymph and tissue homogenates were prepared to evaluate the snail' tissue antioxidants, protein content, lipid profile and apoptosis. The results obtained revealed that superoxide dismutase, glutathione-S-transferase, glutathione peroxidase, catalase, reduced glutathione, glutathione reductase levels were decreased while malondialdehyde, protein carbonyl, total protein, albumin, globulin, cholesterol, low density lipoprotein and triglycerides levels were increased in Schistosoma infected snails' tissues. Schistosoma also induced apoptosis in snails' tissues homogenates. Sodium fluoride restores all the above parameters to approach the control uninfected snails levels. In conclusion, sodium fluoride inhibits oxidative stress and apoptosis produced in Schistosoma infected snails and consequently it is be useful to be used in Schistosoma infection inhibition where sodium fluoride at higher dose was more effective than the lower two doses.

Role of CCR5Δ32 mutation in protecting patients with Schistosoma mansoni infection against hepatitis C viral infection or progression

Schistosomiasis has been incriminated in the significant increase in hepatitis C virus (HCV) infections, although the association has not been adequately explained. We hypothesized that the CCR5Δ32 mutation may be involved in the high prevalence of HCV with schistosomiasis. The aim was to explore the association between the CCR5Δ32 mutation in schistosomiasis patients and protection against HCV infection or progression. We compared 220 schistosomiasis patients (S group) and 190 patients with HCV and schistosomiasis (HCV/S group) for the presence of the CCR5Δ32 mutation. Clinical, biochemical, and radiological assessments were done. HCV infection was diagnosed with anti-HCV antibodies and a recombinant HCV antigen-based rapid immunochromatographic test, and confirmed by HCV reverse transcriptase PCR. HCV genotyping was done by reverse hybridization line probe assay. Schistosomiasis was diagnosed by FAST-ELISA and indirect hemagglutination for Schistosoma mansoni antibodies, and stool analysis for ova. Polymorphisms of the CCR5 receptor gene were assessed by PCR-based genotyping of the 32-bp deletion at the CCR5 locus in whole blood. Of HCV/S patients, 91.6 vs. 91.8 % of S patients had CCR5 WT/WT homozygosity (nonmutants). Heterozygous and homozygous CCR5Δ32 mutation patterns (CCR5Δ32/WT and CCR5Δ32/Δ32) were distributed similarly in the HCV/S and S groups (6.8 vs. 7.2 % and 0.53 vs. 0.90 %, respectively; p > 0.05, OR = 0.97). Genotype 4 was the predominant viral genotype (93 % of cases). No differences were observed in CCR5 gene patterns according to viral genotype, viral RNA count, or ALT level. However, CCR5Δ32 mutants (homozygous and heterozygous) had a lower rate of severe hepatic fibrosis vs. nonmutants (27 vs. 42 %, p = 0.101, OR = 0.51). Moreover, 53.4 % of CCR5Δ32/WT mutants showed spontaneous viral clearance vs. 26.2 % of nonmutants (p = 0.000, OR = 4.1). In conclusion, no association was detected between the CCR5Δ32 mutation and HCV disease susceptibility in schistosomiasis patients. However, patients with the CCR5Δ32 mutation and HCV infection were less prone to severe hepatic fibrosis and more likely to have spontaneous viral clearance than patients with the nonmutant genotype.

Schistosoma haematobium infections among schoolchildren in central Sudan one year after treatment with praziquantel

Background

Chemotherapy with praziquantel (PZQ) is the mainstay of schistosomiasis control. However, there are recent concerns about tolerance or resistance to PZQ, so that monitoring its efficacy in different settings is required.

Methods

A longitudinal study was conducted to evaluate the impact of PZQ for the treatment of Schistosoma haematobium infection among schoolchildren at Al Salamania, Central Sudan. Parasitological examinations for S. haematobium were performed in a cohort of schoolchildren (6–15 years of age) before and 1 year after treatment with a single dose of PZQ 40 mg/kg.

Results

Out of 562 (309 boys and 253 girls) schoolchildren recruited from three elementary schools, 420 completed one longitudinal dataset that comprised of data from two time points; baseline, and follow-up 1 year after treatment with a single dose of PZQ 40 mg/kg for S. haematobium infection. A single dose of PZQ significantly reduced the prevalence of S. haematobium infection by 83.3% (from 51.4% to 8.6%) and the geometric mean intensity of infection of positive individuals by 17.0% (from 87.7 to 72.8 eggs/10 ml of urine) 1 year after treatment. While there was no significant difference in the reduction of the prevalence of S. haematobium infection between the gender or age groups, there was a significantly higher reduction of intensity of S. haematobium infection among girls in comparison with boys.

Conclusion

There was a significant reduction of S. haematobium infection 1 year after PZQ treatment in this setting.

The efficacy of NP11-4-derived immunotoxin scFv-artesunate in reducing hepatic fibrosis induced by Schistosoma japonicum in mice

Schistosomiasis is one of the most prevalent parasitic diseases in China, and hepatic fibrosis caused by schistosome infection is the principal cause of death. The aim of this study was to evaluate the efficacy of NP11-4-derived immunotoxin scFv-artesunate on Schistosoma japonicum-induced hepatic fibrosis. A single-chain variable fragment (scFv) was generated from the murine anti-Schistosoma japonicum (S. japanicum) monoclonal antibody NP11-4. The scFv was expressed as a soluble protein and purified by Ni-affinity chromatography. After conjugation with artesunate, the binding ability with soluble egg antigens (SEA) was determined by an enzyme-linked immunosorbent assay (ELISA). The biological activity of purified scFv, scFv-artesunate (immunotoxin), and artesunate was detected in vivo. Image-Pro Plus software was used to analyze the size of egg granuloma and the extent of liver fibrosis. The recombinant scFv expession vector was constructed and expressed successfully. After purification by a His-trap Ni-affinity column, the scFv yield was approximately 0.8 mg/L of culture medium. ELISA results showed that chemical conjugation did not affect the binding activity of the immunotoxin. Our animal experiments indicated that the immunotoxin could significantly reduce the size of egg granuloma in the liver and inhibit hepatic fibrosis. The immunotoxin could be used as a promising candidate in the targeted therapy of S. japonicum-induced hepatic fibrosis.

Schistosomiasis haematobium prevalence and risk factors in a school-age population of peri-urban Lusaka, Zambia

Given association of the parasite Schistosoma haematobium with coastal and rural/agricultural populations, there is little documentation to date of infection patterns in today's rapidly urbanizing non-coastal regions. We conducted an observational study of 5-17-year-old school children (N = 1583) in peri-urban compounds of Lusaka, Zambia. Demographic information, medical history, physical examination findings and urinalysis results were recorded. Prevalence of schistosomiasis in the population was 20.72%. Significant risk factors for infection were male gender [odds ratio (OR) 2.42], age of 9-12 years or 13-17 years (OR 3.33 and 3.26, respectively, compared with 5-8-year-olds) and single and/or double orphan status (OR 1.43). Clinical officers detected schistosomiasis with a sensitivity of 24.70% and a specificity of 98.17% after history and physical examination. These results reveal that peri-urban populations have a significant but under-recognized vulnerability to infection, and suggest that only history and physical examination are inadequate for identifying a treatment population.

A wake up call for urinary schistosomiasis: reconciling research effort with public health importance

This review considers the current status of urinary schistosomiasis, caused by infection with Schistosoma haematobium, and argues that greater research effort and focus are needed to improve understanding of this neglected tropical disease (NTD). The inappropriateness of relying solely on data concerning the much more extensively studied intestinal form of schistosomiasis caused by S. mansoni is highlighted. The current lack of genome and transcriptome information for S. haematobium is directly hindering further targeted research and must be quickly rectified. Recent molecular phylogenies caution the expectation of similarities between schistosome species and highlight the close relationships of species within the S. haematobium group. Treatment, current and prospective drugs and vaccines, together with diagnosis are considered, highlighting the differences associated with urinary schistosomiasis. This infection has a significant and specific impact on the urino-genital system and has a strong association with bladder cancer, leading to severe and chronic morbidity. There is a clear need for new clinical initiatives in this area to better quantify the disease burden. Furthermore, emerging associations with HIV and other pathogens need to be closely monitored. Research is urgently needed to improve current knowledge in order to develop the next generation of control tools.

Schistosoma mansoni: effect of dietary zinc supplement on egg granuloma in Swiss mice treated with praziqantel

Schistosomiasis is one of the most important parasitic diseases in Egypt and chemotherapy is considered the most effective method of control. This study was conducted to assess the effectiveness of zinc administration against Schistosoma mansoni infection by evaluating the activities of arylesterase and paraoxonase (PON1) enzymes, and the degree of liver damage. One hundred and twenty albino mice were divided into two groups; one was an infected control and the other a treated group which was further subdivided into three according to the praziquantel and zinc supplementation given. Blood and liver samples, collected 10 weeks post-infection, were subjected to parasitological, histopathological, and enzyme assays, and immunological studies. The results showed that dietary zinc supplementation led to marked reduction in worm load, and egg deposition in the liver and intestine. Histopathological examination showed marked reduction in the number and diameter of hepatic granulomas in the treated groups. The activity of arylesterase and PON1 enzymes were partially restored in infected animals receiving zinc. IL-10 mRNA expression was higher in the treated groups than in the infection control group. In conclusion, zinc administration could be a promising adjuvant therapy for S. mansoni infection.

[Is the seric eosinophil cationic protein level a valuable tool of diagnosis in clinical practice?]

SCOPE

The eosinophil cationic protein (ECP) is one of the mediators released during eosinophil activation. These cells are effector cells taking part into the Th2-lymphocyte dependent allergic inflammation. Assaying ECP concentrations in blood and sputum may be useful in evaluating allergic inflammation (asthma and rhinitis). This summary considers the value of measuring ECP levels for the diagnosis of various diseases where an eosinophil-mediated tissue inflammation plays a role.

CURRENT SITUATION AND SALIENT POINTS

Levels of eosinophil cationic protein have been determined in nasal secretions, sputum, gastric secretions, feces and serum. They are increased during seasonal allergic rhinitis and perennial rhinitis, allergic asthma and atopic dermatitis. They are also increased in various gastro-intestinal disorders, some of which are associated with IgE: eosinophil intestinal diseases (esophagitis, gastro-enteritis and colitis), gastro-intestinal food allergy and intestinal parasitoses. Finally, they are increased in non IgE-dependent disorders: non allergic asthma with aspirin intolerance, respiratory infections, sinonasal polyposis, Churg-Strauss disease and idiopathic hyper-eosinophilia (HES) syndrome.

PERSPECTIVES

Assaying serum ECP could help in the diagnosis of several diseases. With parasitic disease the pathogenic progression may be accurately assessed, when serological tests are less indicative. ECP assay may point to non allergic asthma, either Fernand-Widal syndrome or Churg-Strauss disease. As for gastro-intestinal disorders, it indicates an eosinophilic tissue reaction. In the event of isolated hypereosinophilia, ECP assay may clarify whether it is benign or tending towards idiopathic HES. The assay of peroxidase and eosinophil-derived neurotoxin (EDN) should be also considered.

EAU guidelines for the management of urogenital schistosomiasis

More than 100 million people worldwide are affected by bilharziasis, caused by Schistosoma haematobium. For travellers precaution is most important. For the population in endemic areas, an integrated approach including health education is necessary. Effective pharmacologic treatment is available.

Imported schistosomiasis in Europe: sentinel surveillance data from TropNetEurop

BACKGROUND

Schistosomiasis is a major parasitic disease, increasingly imported into temperate climates by immigrants from and travelers to endemic areas.

METHOD

To generate valid data on imported infectious diseases to Europe and to recognize trends over time, the European Network on Imported Infectious Diseases Surveillance (TropNetEurop) was founded in 1999. Three hundred and thirty-three reports of schistosomiasis were analyzed for epidemiologic and clinical features.

RESULTS

Male patients accounted for 64% of all cases. The average age of all patients was 29.5 years. The majority of patients were of European origin (53%). Europeans traveled predominantly for tourism (52%). Main reasons for travel for people from endemic areas were immigration and refuge (51%) and visits to relatives and friends (28%). The majority of infections were acquired in Africa; 92 infections were clearly attributable to Schistosoma haematobium, 130 to Schistosoma mansoni, and 4 to Schistosoma intercalatum. Praziquantel was the only treatment used. No deaths were recorded.

CONCLUSION

TropNetEurop sentinel provides valuable epidemiologic and clinical data on imported schistosomiasis to Europe.