Renal function in Sudanese school children with Schistosoma mansoni infection

Profile of T and B lymphocytes in individuals resistant to Schistosoma mansoni infection

The mechanisms involved in the development of resistance to infection/reinfection by Schistosoma mansoni still arouse great interest and controversy. Some authors demonstrate that resistance to infection is attributed to a mixed Th1 and Th2 response and resistance to reinfection after repeated treatments through mechanisms associated with the Th2 response. Through flow cytometry, the phenotypic characterization of B and T lymphocytes in individuals residing in endemic areas with low parasite loads over 10 years was evaluated for the first time in humans. In this study, individuals with low parasite loads for Schistosoma mansoni had a higher proportion of Th1 and Th2 cells. In addition, lymphocytes from these individuals showed a higher degree of expression of costimulatory molecules CD28 and CTLA-4 and regulatory molecules FoxP3 and IL-10, when compared to individuals with high parasite loads. Our data indicate that the control of the parasite load of S. mansoni must be associated with a Th1, Th2, and regulatory response, and that further studies are needed to elucidate the possibility of mechanisms associated with the hyporesponsiveness of lymphocytes from individuals with high parasite loads.

Childhood nephrotic syndrome in tropical Africa: then and now

This descriptive and comparative review examines the changing epidemiology, treatment, renal and patient outcome of childhood nephrotic syndrome (NS) in tropical Africa (TpAfr). In the 1960s to 1980s, corticosteroid-resistant non-minimal change disease (nMCD) including quartan malaria nephropathy (QMN) was the dominant renal histopathology type. The overall incidence of NS was 0.35-1.34% of hospital admissions. Median age at onset of NS ranged between 4.0 and 12.0 years while the mean (SD) age range was 5.8 (3.8) to 10.3 (4.8) years across studies. The male: female ratio was 1.6:1.0. The overall mean (SD) incidence of idiopathic minimal change disease (MCD) [21.6 (18.6%)] compared with idiopathic nMCD [59.1 (25.7%)] demonstrates significant dominance of the latter (p = 0.0001). Post-1989, the following mean (SD) incidences of histopathological types were: MCD 20.4 (17.7%), focal segmental glomerulosclerosis 39.0 (26.3%), membranoproliferative glomerulonephritis 25.4 (16.8%), proliferative glomerulonephritis 16.7 (27.0%) and membranous nephropathy 7.4 (4.5%). While the mean (SD) proportion of steroid resistance (SR) [73.5 (19.2%)] was significantly greater than the mean complete remission (CR) [26.5 (19.2%)] during 1960-1989 (p=0.005), mean (SD) SR [27.4 (25.3%)] was significantly lower than mean (SD) CR [66.1 (28.0%)] post-1989 (p < 0.001). Unlike QMN, hepatitis B virus, HIV infection, sickle cell disease and systemic lupus erythematosus are now increasingly being associated with NS in TpAfr. Mean (SD) renal survival post-1989 was 58.3 (37.0%) while all-cause mortality was 9.8%. Children with NS now survive better than before, reflecting improved access to healthcare and transition to a clinical pattern favouring idiopathic NS and increased sensitivity to corticosteroids.

The influence of HIV and schistosomiasis on renal function: a cross-sectional study among children at a hospital in Tanzania

Background

Schistosomiasis and HIV are both associated with kidney disease. Prevalence and factors associated with abnormal renal function among HIV-infected children in Africa compared to uninfected controls have not been well described in a schistosomiasis endemic area.

Methodology/Principal Findings

This cross-sectional study was conducted at the Sekou Toure Regional Hospital HIV clinic in Mwanza, Tanzania. A total of 122 HIV-infected children and 122 HIV-uninfected siblings were consecutively enrolled. Fresh urine was obtained for measurement of albuminuria and Schistosoma circulating cathodic antigen. Blood was collected for measurement of serum creatinine. Estimated glomerular filtration rate (eGFR) was calculated using the modified Schwartz equation. Renal dysfunction was defined operationally as eGFR<60mL/min/1.73m2 and/or albuminuria>20mg/L in a single sample. Among 122 HIV-infected children, 61/122 (50.0%) met our criteria for renal dysfunction: 54/122 (44.3%) had albuminuria>20mg/L and 9/122 (7.4%) had eGFR<60. Among 122 HIV-uninfected children, 51/122 (41.8%) met our criteria for renal dysfunction: 48/122 (39.3%) had albuminuria>20mg/L and 6/122 (4.9%) had eGFR<60. Schistosomiasis was the only factor significantly associated with renal dysfunction by multivariable logistic regression (OR = 2.51, 95% CI 1.46–4.31, p = 0.001).

Conclusions/Significance

A high prevalence of renal dysfunction exists among both HIV-infected Tanzanian children and their HIV-uninfected siblings. Schistosomiasis was strongly associated with renal dysfunction.

Ninety percent of schistosomiasis occurs in sub-Saharan Africa, where 91% of HIV-infected children reside. Both schistosomiasis and HIV affect the kidney, but their respective effects on kidney disease in children are not well described. Our prior work in HIV-infected adults demonstrated a high prevalence of kidney disease, possibly worsened by schistosomiasis, but adults are less commonly and less heavily infected with schistosomiasis than children. Therefore, we sought to describe the prevalence and factors associated with renal dysfunction (defined operationally as eGFR <60mL/min/1.73m² and/or albuminuria >20mg/L in a single urine test) among HIV-infected children and their uninfected siblings living in a schistosomiasis endemic area. We found that half of HIV-infected children and more than one third of HIV-uninfected children had renal dysfunction. Schistosomiasis was the only factor significantly associated with renal dysfunction, increasing odds of renal dysfunction by 2.5-fold. Nearly 50% of the renal dysfunction we observed in both groups could be explained by schistosomiasis. The strong association between schistosomiasis and renal dysfunction among both HIV-infected and uninfected children should remind clinicians to screen for schistosomiasis. It also ought to spur further prospective research to assess for causality and outcomes in the relationship between S. mansoni and kidney disease in children.

Malaria-induced renal damage: facts and myths

Malaria infections repeatedly have been reported to induce nephrotic syndrome and acute renal failure. Questions have been raised whether the association of a nephrotic syndrome with quartan malaria was only coincidental, and whether the acute renal failure was a specific or unspecific consequence of Plasmodium falciparum infection. This review attempts to answer questions about "chronic quartan malaria nephropathy" and "acute falciparum malaria nephropathy". The literature review was performed on all publications on kidney involvement in human and experimental malarial infections accessible in PubMed or available at the library of the London School of Hygiene and Tropical Medicine. The association of a nephrotic syndrome with quartan malaria was mostly described before 1975 in children and rarely in adult patients living in areas endemic for Plasmodium malariae. The pooled data on malaria-induced acute renal failure included children and adults acquiring falciparum malaria in endemic areas either as natives or as travellers from non-tropical countries. Non-immunes (not living in endemic areas) had a higher risk of developing acute renal failure than semi-immunes (living in endemic areas). Children with cerebral malaria had a higher rate and more severe course of acute renal failure than children with mild malaria. Today, there is no evidence of a dominant role of steroid-resistant and chronic "malarial glomerulopathies" in children with a nephrotic syndrome in Africa. Acute renal failure was a frequent and serious complication of falciparum malaria in non-immune adults. However, recently it has been reported more often in semi-immune African children with associated morbidity and mortality.

Nephrotic syndrome in African children: lack of evidence for ‘tropical nephrotic syndrome’?

BACKGROUND

Infections such as malaria, schistosomiasis, hepatitis B and HIV have been suggested as major causes of the nephrotic syndrome (NS) in African children. We retrospectively analysed the course of the NS in 32 children from Ghana and reviewed the literature on NS from 18 different African countries for the presence of 'the tropical nephrotic syndrome'.

METHODS

Thirty-two children (22 boys, 10 girls, median age 12 years, range 1-18 years) with NS were treated from 2000-2003 at Battor Hospital, Ghana. Thirteen out of 32 children underwent a renal biopsy which was investigated by light, immune and electron microscopy. All 32 patients were initially treated with oral prednisone (PRED) therapy (29 with standard therapy for 8 weeks and three individually tailored), and steroid-resistant children received also intravenous methylprednisolone pulses (three children) or oral cyclophosphamide (two children).

RESULTS

All patients fulfilled the clinical and laboratory criteria of a NS. The initial median serum creatinine was 65 micromol/l (range 44-133 micromol/l). Renal biopsy was performed in 13/32 children and revealed focal and segmental glomerulosclerosis (FSGS) in 10 patients, minimal change disease (MCNs) in two and no conclusive result in one patient. Glomerular immune complex deposition was absent in all biopsies. After treatment with PRED, oedema disappeared in 24/32 patients; however, proteinuria normalized in 16/32 patients only. The NS relapsed in 9/16 steroid-sensitive patients after cessation of PRED therapy, and two children were frequent relapsers. The steroid-resistant NS did not respond to an intensified immunosuppression in 5/16 children receiving methylprednisolone or cyclophosphamide. Five out of 32 children died, all were steroid resistant.

CONCLUSIONS

There was no evidence for a dominating role of steroid-resistant 'tropical glomerulopathies' in children with a NS in Ghana. Similar to South Africa, focal and segmental glomerulosclerosis (FSGS) and minimal change disease were the most frequent findings on histology. Contrary to Nigeria, membrano-proliferative glomerulonephritis was not found in these patients. We conclude from this data and from the literature that the histological pattern of NS may vary between different African countries. Concerning therapy of NS under tropical conditions, we emphasize that despite the limited therapeutic facilities half of these patients may benefit from corticosteroids; however, steroid resistance and FSGS resulted in a high mortality.

Partial and complete de Toni-Debré-Fanconi syndrome after ifosfamide chemotherapy of childhood malignancy

Ten out of 79 patients treated with ifosfamide (IFO) developed a complete (n = 2) or partial (n = 8) de Toni-Debré-Fanconi syndrome (RFS). All but one of these patients had been treated in addition with cisplatinum (CPL) or had undergone radiotherapy to the abdomen or nephrectomy as part of the overall treatment for malignancy. A detailed nephrological work-up of proximal tubular function showed decreased fractional phosphate and percent aminoacid reabsorption in 37.1 and 56.7% of cases, respectively, and the excretion of alpha 1-microglobulin and N-acetyl-beta-D-glucosaminidase was elevated in 44.4 and 23.5%. Glomerular function was well preserved in the majority of patients. Tubular dysfunction was confirmed by silver-stained SDS PAGE of urine which showed mostly low molecular weight proteinuria. CPL has been shown to result in renal magnesium loss and reduced glomerular filtration rate, and its toxicity clearly differs from IFO-mediated tubulopathy. Our data suggest that subclinical impairment of proximal tubular function was significantly increased by additional CPL therapy. We conclude that CPL may enhance IFO-mediated nephrotoxicity and that a substantial number of patients is at risk of developing persistent tubular dysfunction leading to metabolic bone disease.

Renal involvement in prolonged Salmonella bacteremia: the role of schistosomal glomerulopathy

Renal involvement has been well documented in patients with hepatosplenic schistosomiasis and in patients with prolonged Salmonella bacteremia (PSB). Whether there is a specific renal lesion related to PSB or the chronic bacterial infection aggravates a pre-existing schistosomal glomerulopathy has been a matter of controversy. To analyze the clinical manifestations and histopathological findings of the renal involvement, 8 patients with hepatosplenic schistosomiasis and PSB (group I) were compared with 8 patients with schistosomal glomerulopathy (group II) matched by sex and glomerular disease. The mean age in group I was 17.7 years. All patients presented with hematuria, in 4 cases associated with non-nephrotic proteinuria. In group II the mean age was 23 years; nephrotic syndrome was the clinical presentation in 7 of the 8 patients in the group. All patients in group I experienced remission of the clinical and laboratory abnormalities as the salmonella infection was cured; in group II the patients had persistent, steroid-resistant, nephrotic syndrome. On histological examination, no difference was noted between the two groups, except for pronounced glomerular hypercellularity and interstitial mononuclear cell infiltration in group I. These observations strongly suggest that PSB exacerbates a pre-existing sub-clinical schistosomal glomerulopathy by the addition of active lesions directly related to the prolonged bacteremia.

Urine test strips: reliability of semi-quantitative findings under tropical conditions

Semi-quantitative urinalysis with urine reagent strips (URS) for erythrocyturia (EU), leucocyturia (LU) and proteinuria (PU) was performed in Congolese and Sudanese school children with Schistosoma haematobium and/or S. mansoni infection. Quantitative urinalysis was performed on the same specimen using microscopy and a Neubauer counting chamber for EU and LU and the Coomassie blue dye-binding assay for PU. Microscopically detectable EU of more than 10 cells/microliters was found in 63% of all samples and LU of more than 20 cells/microliters was found in 60% of all samples. With the Coomassie blue method, PU of more than 150 mg/l was detected in 51% of all samples. URS gave positive results of grade 1-3 for EU in 69% of all samples, for LU in 63% of all samples and for PU in 66% of all samples. The sensitivity and specificity of URS compared with standard reference methods were as follow: EU 95% and 75%, LU 81% and 81% and PU 90% and 56%. When the results of all three test were combined, URS differentiated abnormal from normal urine specimens with a sensitivity of 94% and a specificity of 70%. Median quantitative results showed a good correlation with semiquantitative URS readings for all parameters, but there was a wide range of URS scores. We concluded that URS sensitivity detect urinary abnormalities and thus may be used as a general screening method under field conditions when more specific methods cannot be performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal transplantation in 22 children with nephropathic cystinosis

In 1989, 22 children (11 boys, 11 girls aged 8-23 years) with nephropathic cystinosis, who had received a total of 28 renal allografts over the previous 14 years, were reviewed. Nineteen were alive, of whom 17 had functioning grafts 5 months to 13 years after transplantation. The mean serum creatinine level in these 17 was 135 mumol/l. Patient and graft survival did not differ from non-cystinotic children. Persistent hypothyroidism was found in 3 patients, transient diabetes mellitus in 1, severely disturbed vision in 1 and brain atrophy in 11. Arterial hypertension was present in 16 patients. Growth retardation was universal, although in 4 patients on cyclosporin A post-transplant catch-up growth occurred. Five patients over 15 years completed puberty. Readjustment in terms of school performance was good but was less good for psychosocial development. None of the patients had ever been treated with cystine-depleting agents; the data will therefore provide a historical control group with which to compare the results from a group treated with these agents.