Quartan malarial nephrotic syndrome in children

Immunogenic and diagnostic potential of recombinant apical membrane antigen-1 from Plasmodium malariae

The apical membrane antigen-1 (AMA-1) is a crucial target for malaria management and prevention strategies. While the immunogenicity of AMA-1 has been extensively studied for Plasmodium falciparum and Plasmodium vivax, there is a notable scarcity of information for Plasmodium malariae. In this study, recombinant PmAMA-1 was expressed in Escherichia coli, and its integrity was confirmed via western blotting and indirect immunofluorescence assays. Immunization of BALB/c mice with rPmAMA-1 emulsified in Freund's adjuvant resulted in significantly elevated specific IgG antibodies, predominantly IgG1. The immune response exhibited Th1, Th2, and Th17 phenotypes, with a notable Th1 bias. Antisera from immunized mice effectively recognized native PmAMA-1 on P. malariae. These results suggest that PmAMA-1 is a promising target for both vaccine development and diagnostic applications for P. malariae infections, offering dual preventive and diagnostic benefits in malaria control.

Structural organization and sequence diversity of the complete nucleotide sequence encoding the Plasmodium malariae merozoite surface protein-1

The merozoite surface protein-1 (MSP1) is a prime candidate for an asexual blood stage vaccine against malaria. However, polymorphism in this antigen could compromise the vaccine’s efficacy. Although the extent of sequence variation in MSP1 has been analyzed from various Plasmodium species, little is known about structural organization and diversity of this locus in Plasmodium malariae (PmMSP1). Herein, we have shown that PmMSP1 contained five conserved and four variable blocks based on analysis of the complete coding sequences. Variable blocks were characterized by short insertion and deletion variants (block II), polymorphic nonrepeat sequences (block IV), complex repeat structure with size variation (block VI) and degenerate octapeptide repeats (block VIII). Like other malarial MSP1s, evidences of intragenic recombination have been found in PmMSP1. The rate of nonsynonymous nucleotide substitutions significantly exceeded that of synonymous nucleotide substitutions in block IV, suggesting positive selection in this region. Codon-based analysis of deviation from neutrality has identified a codon under purifying selection located in close proximity to the homologous region of the 38 kDa/42 kDa cleavage site of P. falciparum MSP1. A number of predicted linear B-cell epitopes were identified across both conserved and variable blocks of the protein. However, polymorphism in repeat-containing blocks resulted in alteration of the predicted linear B-cell epitope scores across variants. Although a number of predicted HLA-class II-binding peptides were identified in PmMSP1, all variants of block IV seemed not to be recognized by common HLA-class II alleles among Thai population, suggesting that diversity in this positive selection region could probably affect host immune recognition. The data on structural diversity in PmMSP1 could be useful for further studies such as vaccine development and strain characterization of this neglected malaria parasite.

Global prevalence and mortality of severe Plasmodium malariae infection: a systematic review and meta-analysis

Background

Severe complications among patients with Plasmodium malariae infection are rare. This is the first systematic review and meta-analysis demonstrating the global prevalence and mortality of severe P. malariae infection in humans.

Methods

The systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. All research articles published on the severity and mortality of P. malariae infection cases in humans were retrieved from three public databases: PubMed, Scopus, and ISI Web of Science. The pooled prevalence estimate and 95% confidence interval (CI) of complications in patients with P. malariae malaria was analysed using the random-effects model provided in Stata software. The pooled odds ratio (OR) and 95% CI of severe malaria for P. malariae infection and Plasmodium falciparum infection were analysed using Review Manager software.

Results

Six studies were used to estimate the pooled prevalence of severe P. malariae malaria. Out of 10,520 patients infected with P. malariae, the pooled prevalence estimate of severe P. malariae infection was 3% (95% CI 2–5%), with high heterogeneity (I²: 90.7%). Severe anaemia (3.32%), pulmonary complications (0.46%), and renal impairments (0.24%) were the most common severe complications found in patients with P. malariae infection. The pooled proportion of severe anaemia for P. malariae infection and P. falciparum infection was comparable among the four included studies (OR: 0.74, 95% CI 0.22–2.45, I² = 98%). The pooled proportion of pulmonary complications was comparable between patients with P. malariae infection and those with P. falciparum infection among the four included studies (OR: 1.44; 95% CI 0.17–12.31, I²: 92%). For renal complications, the funnel plot showed that the pooled proportion of renal complications for P. malariae infection and P. falciparum infection was comparable among the four included studies (OR: 0.94, 95% CI 0.18–4.93, I²: 91%). The mortality rate of patients with P. malariae infection was 0.17% (18/10,502 cases).

Conclusions

This systematic review demonstrated that approximately two percent of patients with P. malariae infection developed severe complications, with a low mortality rate. Severe anaemia, pulmonary involvement, and renal impairment were the most common complications found in patients with P. malariae infection. Although a low prevalence and low mortality of P. malariae infection have been reported, patients with P. malariae infection need to be investigated for severe anaemia and, if present, treated aggressively to prevent anaemia-related death.

Selective whole genome amplification of Plasmodium malariae DNA from clinical samples reveals insights into population structure

The genomic diversity of Plasmodium malariae malaria parasites is understudied, partly because infected individuals tend to present with low parasite densities, leading to difficulties in obtaining sufficient parasite DNA for genome analysis. Selective whole genome amplification (SWGA) increases the relative levels of pathogen DNA in a clinical sample, but has not been adapted for P. malariae parasites. Here we design customized SWGA primers which successfully amplify P. malariae DNA extracted directly from unprocessed clinical blood samples obtained from patients with P. malariae-mono-infections from six countries, and further test the efficacy of SWGA on mixed infections with other Plasmodium spp. SWGA enables the successful whole genome sequencing of samples with low parasite density (i.e. one sample with a parasitaemia of 0.0064% resulted in 44% of the genome covered by ≥ 5 reads), leading to an average 14-fold increase in genome coverage when compared to unamplified samples. We identify a total of 868,476 genome-wide SNPs, of which 194,709 are unique across 18 high-quality isolates. After exclusion of the hypervariable subtelomeric regions, a high-quality core subset of 29,899 unique SNPs is defined. Population genetic analysis suggests that P. malariae parasites display clear geographical separation by continent. Further, SWGA successfully amplifies genetic regions of interest such as orthologs of P. falciparum drug resistance-associated loci (Pfdhfr, Pfdhps, Pfcrt, Pfk13 and Pfmdr1), and several non-synonymous SNPs were detected in these genes. In conclusion, we have established a robust SWGA approach that can assist whole genome sequencing of P. malariae, and thereby facilitate the implementation of much-needed large-scale multi-population genomic studies of this neglected malaria parasite. As demonstrated in other Plasmodia, such genetic diversity studies can provide insights into the biology underlying the disease and inform malaria surveillance and control measures.

Mouse NC/Jic strain provides novel insights into host genetic factors for malaria research

Malaria is caused by Plasmodium parasites and is one of the most life-threatening infectious diseases in humans. Infection can result in severe complications such as cerebral malaria, acute lung injury/acute respiratory distress syndrome, and acute renal injury. These complications are mainly caused by P. falciparum infection and are major causes of death associated with malaria. There are a few species of rodent-infective malaria parasites, and mice infected with such parasites are now widely used for screening candidate drugs and vaccines and for studying host immune responses and pathogenesis associated with disease-related complications. We found that mice of the NC/Jic strain infected with rodent malarial parasites exhibit distinctive disease-related complications such as cerebral malaria and nephrotic syndrome, in addition to a rapid increase in parasitemia. Here, we focus on the analysis of host genetic factors that affect malarial pathogenesis and describe the characteristic features, utility, and future prospects for exploitation of the NC/Jic strain as a novel mouse model for malaria research.

Infections and the kidney: a tale from the tropics

Tropical infections are caused by a variety of bacteria, viruses and parasitic organisms across varying geographical regions and are more often reported in adults than in children. Most of the infections are acute, presenting as a febrile illness with involvement of multiple organ systems, including the kidney. The gamut of renal manifestations extends from asymptomatic urinary abnormalities to acute kidney injury and-albeit rarely-chronic kidney disease. Tropical infections can involve the glomerular, tubulointerstitial and vascular compartments of the kidney. Leptospirosis, malaria, dengue, rickettsial fever and schistosomiasis are the most prevalent tropical infections which affect the kidneys of children living in the tropics. In this review we discuss renal involvement in these most prevalent tropical infections.

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.

Glomerular Detection of Schistosomal Antigen by Immunoelectron Microscopy in Human Mansonian Schistosomiasis

Schistosomal antigens (S. mansoni) were detected in glomeruli of nine patients with nephropathy and nephrotic syndrome by immunoelectron microscopy. The criteria for patients' selection were presence of intestinal schistosomiasis and absence of any surgical or other medical diseases, particularly lupus erythematosus, syphilis, and hepatitis B and C, which could explain the renal disease. When examined by light microscopy, kidney biopsies showed type I membranoproliferative glomerulonephritis in four patients, focal segmental glomerulosclerosis in two, and mesangioproliferative glomerulonephritis, membranous glomerulonephritis, and minimal change disease in one each of the remaining three patients. Immunofluorescence showed mainly immunoglobulin G (IgG), IgM, and different complement components (C3, Clq) deposits, particularly in the mesangial area, in eight patients. All patients had gold-labeled schistosomal antigen deposits in their glomeruli, chiefly in mesangial cells and matrix, along the glomerular membrane, and occasionally in the cytoplasm of epithelial cells. Although membranous glomerulonephritis has been rarely described in association with schistosomiasis and minimal change disease may be occasionally caused by an infectious disease like syphilis, the absence of definite experimental models and epidemiologic data suggests that coincidental pathologies without causal relationship with schistosomiasis cannot be ruled out to explain these findings.

Plasmodium malariae Infection Associated with a High Burden of Anemia: A Hospital-Based Surveillance Study

Background

Plasmodium malariae is a slow-growing parasite with a wide geographic distribution. Although generally regarded as a benign cause of malaria, it has been associated with nephrotic syndrome, particularly in young children, and can persist in the host for years. Morbidity associated with P. malariae infection has received relatively little attention, and the risk of P. malariae-associated nephrotic syndrome is unknown.

Methodology/Principal Findings

We used data from a very large hospital-based surveillance system incorporating information on clinical diagnoses, blood cell parameters and treatment to describe the demographic distribution, morbidity and mortality associated with P. malariae infection in southern Papua, Indonesia. Between April 2004 and December 2013 there were 1,054,674 patient presentations to Mitra Masyarakat Hospital of which 196,380 (18.6%) were associated with malaria and 5,097 were with P. malariae infection (constituting 2.6% of all malaria cases). The proportion of malaria cases attributable to P. malariae increased with age from 0.9% for patients under one year old to 3.1% for patients older than 15 years. Overall, 8.5% of patients with P. malariae infection required admission to hospital and the median length of stay for these patients was 2.5 days (Interquartile Range: 2.0–4.0 days). Patients with P. malariae infection had a lower mean hemoglobin concentration (9.0g/dL) than patients with P. falciparum (9.5g/dL), P. vivax (9.6g/dL) and mixed species infections (9.3g/dL). There were four cases of nephrotic syndrome recorded in patients with P. malariae infection, three of which were in children younger than 5 years old, giving a risk in this age group of 0.47% (95% Confidence Interval; 0.10% to 1.4%). Overall, 2.4% (n = 16) of patients hospitalized with P. malariae infection subsequently died in hospital, similar to the proportions for the other endemic Plasmodium species (range: 0% for P. ovale to 1.6% for P. falciparum).

Conclusions/Significance

Plasmodium malariae infection is relatively uncommon in Papua, Indonesia but is associated with significant morbidity from anemia and a similar risk of mortality to patients hospitalized with P. falciparum and P. vivax infection. In our large hospital database, one in 200 children under the age of 5 years with P. malariae infection were recorded as having nephrotic syndrome.

Plasmodium malariae is a relatively rare, but widely distributed, cause of malaria. It can persist in the human host for years, often without causing significant symptoms. As a result, P. malariae will be a very difficult species to eradicate. Our study used data from a routine hospital-based surveillance system in southern Papua, Indonesia to describe the clinical epidemiology of P. malariae infections. Over a 10-year period there were 5,097 patient presentations to Mitra Masyarakat Hospital associated with P. malariae infection constituting 2.6% of all malaria cases. Patients with P. malariae malaria had a significantly older age distribution than those with P. vivax infections. They also had lower mean hemoglobin concentrations than patients infected with P. falciparum, P. vivax or mixed Plasmodium species. We speculate that this may be due to chronic hemolysis of parasitized and non-parasitized red cells as a result of persistent infection. One in 200 children under the age of 5 years with P. malariae infection were recorded as having nephrotic syndrome, a well-known but to date unquantified complication. Overall, 0.3% of patients with P. malariae malaria died. These findings emphasize the need to consider this parasite when designing comprehensive malaria elimination strategies.

Glomerulonephropathies in Plasmodium inui-infected rhesus monkey: a primate model and possible applications for human quartan malaria

SUMMARY None of the few animal models proposed for the study of human quartan malaria nephritic syndrome have shown complete pathological findings that are similar to those seen in humans. This study investigated the histopathological changes in kidneys in 10 Plasmodium inui infected Macaca mulatta monkeys by light and electron microscopy in order to develop a suitable animal model for human quartan malaria. Ten healthy adult rhesus monkeys were infected with P. inui and clinical chemistry and haematologic tests were done before and after infection. A renal biopsy sample was collected before infection as a baseline control and another biopsy was collected after infection. Histopathological changes examined by light and transmission electron microscopy (TEM) revealed abnormalities in all infected monkeys to variable degrees. Several electron-dense discrete or diffused mesangial deposits, and increase in mesangial cells and matrix were associated with the morphological changes observed by light microscope. This pattern is consistent with membranoproliferative glomerulonephritis type reported in humans infected with Plasmodium malariae. Results strongly support that the P. inui-infected rhesus monkey develop an immune-complex-mediated glomerulonephritis in the course of the infection. Therefore, this experimental model represents a useful tool to better understand the different parameters and the consequences of quartan malaria infections comparable to situations in humans.

Acute kidney injury associated with Plasmodium malariae infection

According to current estimates, Plasmodium malariae is not very common in Senegal, as more than 98% of malaria cases are suspected to be due to Plasmodium falciparum. However, it is possible that other malarial species are being under-reported or misdiagnosed. This is a report of a case of P. malariae in a 30-year-old man previously hospitalized with acute kidney injury after treatment with quinine and re-hospitalized three months later. He was diagnosed with renal cortical necrosis post malaria treatment. Plasmodium malariae was identified with light microscope and confirmed using species-specific small-subunit rRNA (ssrRNA) amplification.The patient was treated for malaria with intravenous quinine for seven days, followed by three days of oral treatment; the bacterial infection was treated using ceftriaxone during the first hospitalization and ciprofloxacin associated with ceftriaxone the second time. He also had four rounds of dialysis after which he partially recovered the renal function. Given the complications that can be caused by P. malariae infection, it should be systematically looked for, even if the predominant species is P. falciparum in Senegal.

Quartan malaria-associated childhood nephrotic syndrome: now a rare clinical entity in malaria endemic Nigeria

BACKGROUND

The study determined (i) whether or not quartan malaria nephropathy (QMN) is still a major cause of childhood nephrotic syndrome (CNS) in Nigeria, (ii) secondary causes other than QMN and their associated glomerular pathology and (iii) renal and patient outcome.

METHODS

The study was a prospective non-randomized study of consecutive cases of secondary CNS. Patients with idiopathic CNS were excluded.

RESULTS

Twenty-four of 78 (30.8%) CNS cases were of secondary aetiology. Overall mean ages at onset of secondary CNS aetiology and CNS onset were 8.97 +/- 3.59 (1-15.3) and 9.95 +/- 3.15 (5-15.3) years, respectively. Male (14)/female (10) ratio was 1.4. Secondary causes comprised systemic lupus erythematosus (SLE, 37.5%), sickle cell anaemia (SCA, 16.7%), hepatitis B virus (HBV, 16.7%) infection, Churg-Strauss syndrome (12.6%), SLE/human immunodeficiency virus infection (4.2%), rhabdomyosarcoma (4.2%), bee stings (4.2%) and Addison's disease (4.2%). The overall cumulative complete remission (CR) rate was 88.0%. Remission was sustained in 11 of 16 (68.8%) CR patients, while one patient (6.25%) relapsed; the remaining four patients (24.95%) were yet to attain sustained remission. Median relapse-free period was 10.5 (0.75-25) months. Cumulative renal survival was 75.2% at 3 years. Three patients were lost to follow-up, while two died. Overall cumulative patient survival probability at 36 months was 90.8%. All patients were followed for a median period of 12.5 (0.11-36.0) months.

CONCLUSION

Overall outcome of CNS has improved significantly compared to the 1960s and 1970s when the poor outcome of QMN was the predominant glomerular lesion in Nigeria. While quartan malaria-associated nephrotic syndrome has become a rare clinical entity, SLE, SCA and HBV infection have become the major secondary aetiologies of CNS in Nigeria.

Plasmodium malariae: parasite and disease

A review of the life history of Plasmodium malariae, the quartan malaria parasite of humans, is presented. Much of the information is based on data obtained from induced infections in humans who were given malaria therapy for the treatment of neurosyphilis between 1940 and 1963. Prepatent periods (i.e., the time until the first day of parasite detection) fever episodes, and maximum parasitemias as a result of infection with P. malariae were obtained and are presented. Experimental and known vectors of the parasite are also discussed. Splenectomized chimpanzees and New World monkeys are readily infected and serve as sources of parasites and antigens for diagnostic and molecular studies. South American monkeys are naturally infected with a parasite known as Plasmodium brasilianum. This parasite appears to be P. malariae that has adapted from humans to grow in monkeys, probably within the last 500 years. Infection with P. malariae is associated with the production of immune complexes in the kidneys and the associated nephrotic syndrome. The essential lesions are a thickening of the glomerular basement membrane and endocapillary cell proliferation. Studies of monkeys infected with P. malariae indicate the same pathology as that demonstrated in humans.

Epidemiology, pathophysiology, management and outcome of renal dysfunction associated with plasmodia infection

Malaria remains a serious health problem in many parts of the world. It causes high morbidity and claims many lives in developing countries each year. Humans are generally infected by four species of malaria parasites. However, malaria infection caused by Plasmodium malariae or P. falciparum is recognized as an important cause of acute renal failure (ARF) and other renal-related disorders (nephropathy) in infected patients. The increasing incidence of malarial ARF (MARF) and the emergence of clinical malarial infection after renal transplantation represent a serious challenge. Additionally, the impact of immunosuppressive therapies on malarial infection is intricate, complex, and not yet well defined. Pathogenesis of MARF is most likely to be due to immune complex-mediated glomerulonephritis caused by immune-complex deposition and endothelial damage, which may lead to fatal forms of quartan malarial nephropathies. Effects of mechanical, immunologic, cytokine, humoral, acute phase response, and hemodynamics factors in inducing malarial nephropathy have also been postulated. Development of preventive strategies aimed at combating MARF and other renal disorders associated with malaria infection requires (1) prevention of malarial infection, (2) early diagnosis, and (3) early referral to well-equipped centers to provide renal replacement therapy, if necessary, along with antimalarial therapy and support. These measures could significantly reduce mortality and enhance recovery of renal function.

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.

Eosinophilic glomerulonephritis in children in Southwestern Uganda

Acute renal disease is common in sub-Saharan Africa, with high mortality. Its etiology is poorly understood; quartan malaria owing to Plasmodium malariae was implicated in previous series. Few previous studies have included histological data; furthermore, much of the literature pre-dates the human immunodeficiency virus (HIV) epidemic. We report prospective analysis of acute proteinuric renal disease in children in rural Uganda. Clinical and laboratory data are presented on 65 patients (aged 2-14 years, mean 8.4; 35 male, 30 female) in 41 of whom histological diagnosis was obtained by renal biopsy. The most frequent histological finding was endocapillary proliferative glomerulonephritis (GN) in 27/41 cases, in 20 of which eosinophils were very prominent. No cases showed features of HIV nephropathy. Malarial films were positive in 11 cases: all owing to Plasmodium falciparum. Patients were treated with diuretics, antihypertensives, and supportive measures. Corticosteroids were rarely used, being reserved for patients with minimal changes on renal biopsy. Clinical outcomes were fair: 91% of patients survived to discharge. We conclude that acute GN is common in children in Uganda, that an unusual eosinophilic proliferative GN is the most frequent histological finding, that HIV is not implicated as an important factor in this age group, and that good outcomes can be achieved using simple clinical and laboratory diagnostic methods. Renal biopsy in selected cases is feasible and helpful, especially in allowing rational use of corticosteroids and other potentially toxic treatments. Symptomatic treatments and careful supportive care will allow the majority of children to recover.

Pediatric malaria in the developing world

Hundreds of millions of people suffer from malaria, and more than a million children die of malaria each year. Malaria typically presents with fever and headache, but the presentation often is nonspecific. The diagnosis should be based on blood tests, and thick and thin smears are the standard means of identifying parasites. In some areas, chloroquine still is effective as treatment, but other medications are needed in most parts of the world. Patients with severe disease (altered consciousness, marked anemia, and/or respiratory distress) should begin therapy parenterally. Control measures depend on the use of insecticide-treated bednets, early identification and treatment of symptomatic individuals, and intermittent preventive therapy. Progress continues toward the development of a useful vaccine.

Pathology of renal diseases in the tropics

Renal diseases unique to the tropics are those that occur in association with infectious diseases including dengue hemorrhagic fever, typhoid fever, shigellosis, leptospirosis, lepromatous leprosy, malaria, opisthorchiasis, and schistosomiasis. These renal complications can be classified on the basis of their clinical and pathologic characteristics into acute transient reversible glomerulonephritis, chronic progressive irreversible glomerulonephritis, amyloidosis, and acute renal failure (ARF) resulting from acute tubular necrosis, acute tubulointerstitial nephritis, and thrombotic microangiopathy. Certain primary glomerular diseases including immunoglobulin (Ig) M nephropathy and focal segmental and global glomerulosclerosis are prevalent in some tropical countries. Renal complications of venomous snakebites also are common in the tropics. This article discusses and summarizes important works in the literature in respect to the clinical syndromes, pathologic features, and pathogenesis of tropical renal diseases both in humans and experimental animal models.

Nephrotic syndrome associated with Toxocara canis infection

This case report describes nephrotic syndrome in a 7-year-old boy coincident with Toxocara canis infection. This rare association was confirmed by elevated Toxocara-specific IgM titres. Treatment with corticosteroids resulted in remission of renal symptoms as well as abatement of the T. canis infection. The relationship between T. canis infection and glomerular disease is still unclear; nephrotic syndrome may be another manifestation of T. canis infection.

[Occurrence of tertian malaria in a male patient who has never been abroad]

Malaria is estimated to have a worldwide incidence of more than 100 million clinical cases and approximately 1 million deaths per year. Korea, although previously known as an endemic area of tertian malaria (Plasmodium vivax), has been considered free from malaria as there had been no report on indigenous cases since 1984. Recently, however, we experienced an indigenous case of P. vivax infection in a young man who had never been abroad. The patient was a 23-year-old Korean soldier with 18-day history of recurrent fever and chill lasting 4 to 8 hours on alternative days since mid-July 1993. He had lived in Changwon, Kyongsangnam-do, before entering barracks located in Paju-gun, Kyonggi-do on June 1992, and had never been out of Korea. He had no history of blood transfusion nor parenteral use of drugs. The peripheral blood smears showed typical ring forms, trophozoites, and gametocytes of P. vivax, in addition to mild anemia and thrombocytopenia. After confirmation of the diagnosis, he was treated with hydroxychloroquine and primaquine. Follow-up blood smears no more revealed malaria parasites. It is not certain whether the present case is due to a resurgence of indigenous malaria or a secondary infection from introduced malaria. Whichever the source of infection the domestic occurrence of malaria cycle in Korea should be a warning sign in public health point of view.

T cells and macrophages in Trypanosoma brucei-related glomerulopathy

In a previous study, susceptibility for Trypanosoma brucei-related glomerulopathy in mice was shown to be dependent on non-major histocompatibility complex genes. Glomerular disease in this model could not be explained by the production of autoantibodies alone. In order to analyze which part of the defense system, in addition to the B-cell compartment, is involved in the development of this infection-related glomerular disease, groups of athymic (BALB/c rnu/rnu), splenectomized, or macrophage-depleted BALB/c mice were inoculated with T. brucei parasites. Polyclonal B-cell activation, invariably observed in infected BALB/c mice, was absent in BALB/c rnu/rnu mice. Glomerular disease in athymic mice, however, as defined by albuminuria and deposition of immune complexes, was not different from that seen in euthymic infected BALB/c mice. Splenectomy prior to inoculation of parasites led to a decreased incidence of albuminuria in 40% of the animals, whereas splenectomy 21 days after inoculation reduced albuminuria significantly, suggesting a role for spleen cells in the induction of glomerular disease. After macrophage depletion with liposome-encapsulated dichlorodimethylene-diphosphonate, infected BALB/c mice developed significantly higher albuminuria levels for a period up to 2 weeks after depletion. Therefore, it was concluded that the development of T. brucei-related glomerular disease is independent of thymus-matured T cells, while the involvement of macrophages in the development of proteinuria is inhibitory rather than disease inducing. Spleen cells other than thymus-dependent T cells, B cells, and macrophages should be investigated for their role in the pathogenesis of this glomerulopathy.

Cell-mediated pathology during murine malaria-associated nephritis

We have studied the cellular mechanisms involved in the development of nephritis during acute and chronic murine malaria infections induced by Plasmodium vinckei petteri and P. berghei respectively. Albuminuria and uraemia were observed during the early stages of both types of infection, and were associated with glomerular and interstitial hypercellularity. There was a gradual increase in numbers of CD45+ cells from the early stages of both infections onwards. These infiltrates contained CD4+ and CD8+ cells and mononuclear phagocytes. The interstitial and glomerular hypercellularity was due to an influx of inflammatory cells rather than an increase in renal cell division. These findings indicate the importance of cell-mediated immune mechanisms in the development of nephritis during murine malaria and illustrate an example of naturally occurring infection-induced nephritis.

Childhood renal disorders in Nigeria

The common childhood renal disorders in Nigeria are post-infectious acute glomerulonephritis (PIAGN), nephrotic syndrome, hypertension, congenital anomalies and urinary tract infection. Children with PIAGN often present with hypertension, circulatory overload and hypoalbuminaemia. Nephrotic syndrome is characterized by a paucity of minimal change and a poor prognosis. Posterior urethral valves and hydronephrosis are the most frequent congenital anomalies. Children with congenital anomalies present late with advanced disease. The commonest malignancy is nephroblastoma, but Burkitt's lymphoma of the kidney also occurs. Both acute and chronic renal failure present depressing and distressing clinical problems, with an aggressive course and a high morbidity and mortality. Poor socio-economy has adverse effects on the presentation, management and follow-up of Nigerian children with renal disorders.

Schistosoma mansoni: induction of severe glomerulonephritis in female BXSB mice following chronic infection

C57BL/6 (B6) and female BXSB mice were infected with 10 cercariae of Schistosoma mansoni per head in order to examine whether chronic parasite infection induced glomerulonephritis (GN) with polyclonal B-cell activation. Six months after the infection, mice were sacrificed and various immunological and histopathological examinations were performed. The following results were obtained. (1) Severe GN was induced in parasite-infected female BXSB mice. The renal changes were similar to those of male BXSB mice which spontaneously develop lupus-like GN. No substantial renal changes were observed in infected B6 mice. (2) Massive IgG and C3 deposits were found in capillary loops and also at the mesangial area of infected BXSB mice. No significant IC deposits were found in the kidney of infected B6 mice. (3) A high level of IC was detected in sera of some parasite-infected female BXSB mice, though no significant difference in the level of IC was found between infected and control mice. (4) Numbers of spleen IgG-producing cells were significantly increased in infected B6 mice. Infected female BXSB mice with splenomegaly showed higher numbers of IgGPC than uninfected mice, but there was no difference between the groups. These results suggest that genetic backgrounds played an important role in the development of lupus-like GN following the chronic infection of parasite-causing polyclonal B-cell activation.

Schistosomal specific nephropathy leading to end-stage renal failure

In this study 17 patients, 11 with end-stage renal failure and six with nephrotic syndrome were selected. The selection criteria were presence of active intestinal schistosomiasis and absence of any surgical or other medical disease which could explain the renal disease. When examined by light microscopy, kidney biopsies showed membranoproliferative glomerulonephritis in nine, membranous in four, focal segmental glomerulosclerosis in two, sclerosing glomerulonephritis in one case, and no changes in another case. Direct immunofluorescence showed IgG deposits in 13 cases, IgM in 10 and different complement components (C3, C1q) in eight cases. Eluates from the kidney biopsies of the 17 schistosomal as well as six control cases were examined by ELISA against schistosoma mansoni adult worm antigen (AWA). This test showed the presence of antibodies against the AWA in 12 out of 17 of the schistosomal cases, and zero out of six of the controls. When examined by direct IFA using sheep anti-circulating anodic antigen/FITC and by indirect IFA using monoclonal antischistosomal CAA IgG3, kidney biopsies of the ELISA positive cases showed granular deposits of circulating anodic antigen (CAA). We conclude that schistosomal specific nephropathy does exist in the clinical settings and can lead to end-stage renal disease, with CAA probably being a major responsible antigen.

Immune complex glomerulopathy in a child with food hypersensitivity

This report describes the occurrence of immune complex glomerulonephritis in a patient with eosinophilic gastroenteritis and food hypersensitivity. A coincident allergen injection may have been a contributing factor in the sudden development of the nephrotic syndrome. Markedly elevated levels of circulating immune complexes (greater than 6400 mg/dl) were found containing kappa-casein and bovine serum albumin (BSA), the latter predominating. Markedly elevated serum BSA hemagglutinating titers were also present (1:40,960). Cross-reacting precipitating antibodies to BSA, beef, and pork were demonstrated, but not to flounder or ovalbumin. Renal biopsy revealed immune complex glomerulonephritis with BSA, immunoglobulins M and G and complement deposited focally in the glomerular basement membrane. With strict dietary limitation of identified causative antigens and prednisone therapy, CIC levels decreased to 16,000 micrograms/dl and serum BSA antibody hemagglutinating titer fell 32-fold over a period of 15 months. There was prompt symptomatic relief and amelioration of signs of nephritis. The patient was able to consume a diet normal in protein and caloric content, and statural catch-up growth occurred. Recognition of food antigens to which the patient was hypersensitive provided a rationale for the relief of the gastrointestinal disturbance, growth stunting, and renal disease.

The role of infectious agents in the aetiology and pathogenesis of childhood nephrotic syndrome in Africa

Childhood nephrotic syndrome is common in Africa where infectious agents are prevalent. This paper reviews the possible aetiological role of infectious agents in childhood nephrotic syndrome in Africa. There is a strong association, possibly causal, between childhood nephrotic syndrome on the one hand and Plasmodium malariae, Schistosoma mansoni and hepatitis B antigens on the other. Beta-haemolytic streptococci are less strongly associated with nephrotic syndrome, and a few other organisms are suspect. The many ubiquitous infectious agents and the prevalence of multiple infections make it difficult to define the role of any single infectious agent or to determine the interaction between the various agents. Control or eradication of infectious diseases should lower the incidence of childhood nephrotic syndrome in Africa.

Biochemical hypothyroidism in Nigerian children with nephrotic syndrome

The nephrotic syndrome in Nigerian children is known to be largely associated with the endemicity of quartan malaria. Routine thyroid function studies were carried out on 24 children with clinical and biochemical evidence of the nephrotic syndrome. The children, aged four to 14 years, were all in the active phase of their disease, presenting with facial and pedal oedema and ascites. There was severe hypoalbuninaemia [mean (S.E.); 19.2 (1.1) g/l], hypercholesterolaemia; 10.5 (1.0) mmol/l and severe albuminuria ranging from 1 to 10 g/l. There was no clinical evidence of thyroid disease. The results of thyroid function tests in these children were compared with those of 181 apparently healthy children of the same age range. The mean total serum thyroxine levels (S.E.) were 118.3 (2.6) and 50.0 (6.4) nmol/l in controls and patients, respectively; T3 resin uptake values were 29.8 (0.2)% and 33.1 (1.2)%; the free thyroxine index (FTI) was 34.7 (0.8) and 16.7 (1.9) while thyrotropin (TSH) levels were 4.8 (0.2) and 10.6 (1.0) mU/l (IRP. MRC 68/38), respectively. The findings of low levels of thyroxine and FTI in association with high levels of TSH suggest that a state of primary hypothyroidism exists in these nephrotic children.

The role of hepatitis B surface antigen in Nigerian children with nephrotic syndrome

Hepatitis B surface antigen was detected by radioimmunoassay in the sera of 18 out of 50 (36%) children with nephrotic syndrome and in 28 of 61 (45.9%) controls. Immunofluorescent studies of kidney biopsies showed HBsAg, IgG, IgM and C3 deposits in a granular pattern in the biopsies of 12 children with nephrotic syndrome and in none of the control kidney biopsies, even though there was no significant difference between the frequencies of HBsAg in the sera of these two groups. We conclude that these findings are indicative of an aetiologic role for HBsAg in these patients.