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

Factors Associated with Acute Kidney Injury among Children with Severe Malaria at Kiryandongo General Hospital, Uganda

Background

Malaria remains one of the leading health problems of the developing world, and acute kidney injury (AKI) is a well-recognized complication of severe malaria in adults; but the clinical importance of AKI in paediatric severe malaria is not well documented. Knowledge of the prevalence and factors associated with AKI among children with severe malaria is among the key strategies, which can help to reduce the burden of AKI among this vulnerable group. Methodology. A hospital-based prospective cross-sectional descriptive and analytic study of children with severe malaria was carried out at Kiryandongo General Hospital. The study involved 350 children with severe malaria attending the study site from August to October 2021. Questionnaires were administered to caretakers to obtain sociodemographic characteristics. Medical data were obtained through physical examination followed by laboratory tests. Blood samples were tested for creatinine and blood smear for malaria. Data were analyzed using binary logistic regression (bivariate and multivariate) to assess for the factors associated with AKI. A p value < 0.05 was considered statistically significant.

Results

The mean age of children with severe malaria was 7.0 ± 3.8 years, and 54.3% of them were male. Of the 350 children enrolled, 167 had AKI, giving an overall AKI prevalence of 47.7% (95% CI: 42.5-53.0). The factors that were significantly associated with AKI among children with severe malaria included caretaker with no formal education (aOR = 21.0, 95% CI: 1.68-261.18, p = 0.018), caretaker with primary education level (aOR = 4.5, 95% CI: 1.41-14.12, p = 0.011), age of child < 5 years (aOR = 1.8, 95% CI: 1.07-2.88, p = 0.025), history of receiving NSAIDs (aOR = 5.6, 95% CI: 2.34-13.22, p < 0.001), moderate anemia (aOR = 3.1, 95% CI: 1.39-6.94, p = 0.006), and severe anemia (aOR = 3.8, 95% CI: 1.66-8.55, p = 0.002).

Conclusion

The prevalence of AKI was high among children with severe malaria in Kiryandongo General Hospital. Acute kidney injury among children with severe malaria was associated with low level of education of caretakers, age of children less than 5 years, history of receiving NSAIDs, and anemia. The management of severe malaria should include screening for AKI especially in children under five years of age, anemic, and those who have received NSAIDs.

Exploring the Role of Antioxidants to Combat Oxidative Stress in Malaria Parasites

BACKGROUND

Malaria, a global challenge, is a parasitic disease caused by Plasmodium species. Approximately 229 million cases of malaria were reported in 2019. Major incidences occur in various continents, including African and Eastern Mediterranean Continents and South-East Asia.

INTRODUCTION

Despite the overall decline in global incidence from 2010 to 2018, the rate of decline has been almost constant since 2014. The morbidity and mortality have been accelerated due to reactive oxygen species (ROS) caused by oxidative stress generated by the parasite responsible for the destruction of host metabolism and cell nutrients.

METHODS

The excessive release of free radicals is associated with the infection in the animal or human body by the parasites. This may be related to a reduction in nutrients required for the generation of antioxidants and the destruction of cells by parasite activity. Therefore, an intensive literature search has been carried out to find the natural antioxidants used to neutralize the free radicals generated during malarial infection.

RESULTS

The natural antioxidants may be useful as an adjuvant treatment along with the antimalarial chemotherapeutics to reduce the death rate and enhance the success rate of malaria treatment.

CONCLUSION

In this manuscript, an attempt has been made to provide significant insight into the antioxidant activities of herbal extracts against malaria parasites.

A systematic analysis of ultrastructural lesions in the Plasmodium coatneyi splenectomized rhesus macaque model of severe malaria

Plasmodium falciparum remains one of the world’s deadliest diseases and with ongoing concerns of evolving drug resistance, there is a need for continued refinement of the Plasmodium coatneyi infection model in macaques to study severe malaria. As such, the systemic ultrastructural lesions associated with P. coatneyi infection in splenectomized rhesus macaques was evaluated in 6 animals. Autopsy samples from multiple areas of the central nervous system (CNS), kidneys, heart, liver, and lungs of all 6 animals were processed for electron microscopy. A systematic analysis of the ultrastructural changes associated with the plasmodium was undertaken by multiple pathologists to ensure consensus. All tissues exhibited marked sequestration of infected red blood cells comprised either of cytoadherence to endothelium or rosette formation, associated with variable degrees of host cell damage in a range of tissues that in severe cases resulted in necrosis. This is the first complete systemic evaluation of ultrastructural tissue lesions in P. coatneyi–infected rhesus macaques, and the findings have important implications evaluating of the use of this model for the study of severe malaria caused by P. falciparum in humans.

Evaluation of Antimalarial Potential of Extracts from Alstonia boonei and Carica papaya in Plasmodium berghei-Infected Mice

Extracts of Alstonia boonei and Carica papaya are used in herbal medicine for the treatment of malaria. This work investigated the phytochemical, antioxidant, and antimalarial effects of hydromethanolic extracts of Alstonia boonei and Carica papaya. A four-day chemosuppressive test was conducted to assess the ability of the extracts to prevent establishment of infection. Three doses of the extracts were administered—100, 200, and 400 mg/kg bw—prior to Plasmodium berghei challenge. Change in body weight, parasitemia, packed cell volume (PCV), and mean survival time was determined. A three-day curative test was also carried out on Plasmodium berghei-infected mice to determine the effects of the plant extracts (200 mg/kg bw) on parasitemia and biochemical indices of liver and kidney functions, lipid metabolism, and oxidative stress. The study revealed that the extracts possessed phenolic compounds (34.13 ± 1.90 mg GAE/g for Alstonia boonei and 27.99 ± 1.46 mg GAE/g for Carica papaya) and flavonoids (19.47 ± 1.89 mg QE/g for Alstonia boonei and 18.24 ± 1.36 mg QE/g for Carica papaya). In vitro antioxidant activity measured as total antioxidant power, total reducing power, and DPPH radical scavenging activity showed that the extracts possessed higher antioxidant activity than the reference compounds. The outcome of the chemosuppressive test revealed that whereas Plasmodium berghei-infected mice had high parasitemia, decreased mean survival time, exhibited loss of weight, and had low PCV, treatment with the extracts reversed the effects in a concentration-dependent manner. Similarly, the curative test revealed that the extracts significantly suppressed parasitemia compared with the malaria negative control group. This was mirrored by reversal of indices of hepatic toxicity (AST, ALT, and ALP levels), nephropathy (urea and creatinine levels), oxidative stress (SOD, CAT, GPx, GSH, and lipid peroxides), and dyslipidemia (TC, HDL, and TG levels and HMG-CoA reductase activity) in infected but treated mice compared with negative control. Put together, the results of this study demonstrate that the extracts of Alstonia boonei and Carica papaya possess antimalarial properties and are able to ameliorate metabolic dysregulations that characterize Plasmodium berghei infection. The phytoconstituents in these extracts are believed to be responsible for the pharmacological activity reported in this study.

Predictors of outcome in childhood Plasmodium falciparum malaria

Plasmodium falciparum malaria is classified as either uncomplicated or severe, determining clinical management and providing a framework for understanding pathogenesis. Severe malaria in children is defined by the presence of one or more features associated with adverse outcome, but there is wide variation in the predictive value of these features. Here we review the evidence for the usefulness of these features, alone and in combination, to predict death and other adverse outcomes, and we consider the role that molecular biomarkers may play in augmenting this prediction. We also examine whether a more personalized approach to predicting outcome for specific presenting syndromes of severe malaria, particularly cerebral malaria, has the potential to be more accurate. We note a general need for better external validation in studies of outcome predictors and for the demonstration that predictors can be used to guide clinical management in a way that improves survival and long-term health.

Evaluating the potential of using urine and saliva specimens for malaria diagnosis in suspected patients in Ghana

BACKGROUND

This study aimed at detecting PfHRP2 and pLDH malaria antigens in urine and salivary specimens of suspected malaria patients using RDT kits, and identifying factors influencing the detection of these antigens.

METHODS

Malaria rapid test kit (SD Bioline RDT kit) was used to detect malaria antigens, PfHRP2 and pLDH, in blood, urine and saliva samples received from patients suspected of malaria. Subsequently, malaria parasitaemia was determined. From the same patients, body temperature readings and haemoglobin concentrations were recorded. Also, micro-haematuria and saliva occult blood were determined. Relative to blood, the sensitivities and the performance of urine and saliva as alternative samples were evaluated.

RESULTS

A total of 706 suspected malaria patients provided all three specimens. Prevalence of malaria by microscopy and RDT was 44.2% and 53.9%, respectively. Compared to blood, the sensitivities of urine and saliva were 35.2% and 57.0% respectively. Haemoglobin concentration < 9.9 g/dL, body temperature > 38.7 °C and occult blood influenced the detection of malaria antigens in both urine and saliva. Furthermore, the antigens were not detected in urine and saliva when parasitaemia was < 60,000 parasites/µL and < 40,000 parasites/µL, respectively.

CONCLUSION

Saliva, with or without blood contamination, was found to be more efficient that urine samples. Therefore these non-blood specimens have the potential to be used as non-invasive samples for malaria diagnosis. However, this approach is useful in severe to moderate anaemia, hyperthermia, parasitaemia > 60,000 parasites/µL and samples contaminated with blood.

Kidney biomarkers in tropical infections: an update

Neglected tropical diseases affect over 1 billion people, and cause 170,000 deaths each year. They result in disability, stigma and disfigurement, and also push families into poverty. Tropical infections can involve the kidney, presenting as a wide variety of ways, varying from transient urinary abnormalities to severe acute kidney injury (AKI). It is important to assess renal function in patients with tropical infections for earlier detection of AKI, appropriate treatment and prevention of Chronic Kidney Disease (CKD) outcome in some of them. There was an exponential increase in research on new kidney biomarkers that were earlier and specific for renal damage but few in the scope of tropical infections. In this review, we focus on kidney biomarkers that are being studied in some of the most prevalent tropical infections such as visceral leishmaniasis, leptospirosis, malaria, schistosomiasis and leprosy. Further studies are needed to evaluate the usefulness of renal biomarkers in the early diagnosis of renal diseases associated with tropical infections.

Autoantibodies and Malaria: Where We Stand? Insights Into Pathogenesis and Protection

Autoantibodies are frequently reported in patients with malaria, but whether they contribute to protection or to pathology is an issue of debate. A large body of evidence indicates that antibodies against host-self components are associated to malaria clinical outcomes such as cerebral malaria, renal dysfunction and anemia. Nonetheless, self-reactive immunoglobulins induced during an infection can also mediate protection. In light of these controversies, we summarize here the latest findings in our understanding of autoimmune responses in malaria, focusing on Plasmodium falciparum and Plasmodium vivax. We review the main targets of self-antibody responses in malaria as well as the current, but still limited, knowledge of their role in disease pathogenesis or protection.

Malaria, Collapsing Glomerulopathy, and Focal and Segmental Glomerulosclerosis

BACKGROUND AND OBJECTIVES

Malaria, a potentially life-threatening disease, is the most prevalent endemic infectious disease worldwide. In the modern era, the spectrum of glomerular involvement observed in patients after malarial infections remains poorly described.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We therefore performed a retrospective multicenter study to assess the clinical, biologic, pathologic, and therapeutic characteristics of patients with glomerular disease demonstrated by kidney biopsy in France within 3 months of an acute malaria episode.

RESULTS

We identified 23 patients (12 men), all but 1 of African ancestry and including 10 patients with concomitant HIV infection. All of the imported cases were in French citizens living in France who had recently traveled back to France from an endemic area and developed malaria after their return to France. Eleven patients had to be admitted to an intensive care unit at presentation. Plasmodium falciparum was detected in 22 patients, and Plasmodium malariae was detected in 1 patient. Kidney biopsy was performed after the successful treatment of malaria, a mean of 24 days after initial presentation. At this time, all patients displayed AKI, requiring KRT in 12 patients. Nephrotic syndrome was diagnosed in 17 patients. Pathologic findings included FSGS in 21 patients and minimal change nephrotic syndrome in 2 patients. Among patients with FSGS, 18 had collapsing glomerulopathy (including 9 patients with HIV-associated nephropathy). In four patients, immunohistochemistry with an antibody targeting P. falciparum histidine-rich protein-2 demonstrated the presence of the malaria antigen in tubular cells but not in podocytes or parietal epithelial cells. An analysis of the apoL1 risk genotype showed that high-risk variants were present in all seven patients tested. After a mean follow-up of 23 months, eight patients required KRT (kidney transplantation in two patients), and mean eGFR for the other patients was 51 ml/min per 1.73 m².

CONCLUSIONS

In patients of African ancestry, imported Plasmodium infection may be a new causal factor for secondary FSGS, particularly for collapsing glomerulopathy variants in an APOL1 high-risk variant background.

Novel kidney injury biomarkers in tropical infections: a review of the literature

Tropical diseases are mainly found in the tropical regions of Asia, Africa and Latin America. They are a major Public Health problem in these regions, most of them are considered neglected diseases and remain as important contributors to the development of AKI (Acute Kidney Injury), which is associated with increased patients' morbidity and mortality. In most countries, kidney disease associated to tropical diseases is attended at health services with poor infrastructure and inadequate preventive measures. The long-term impacts of these infections on kidney tissue may be a main cause of future kidney disease in these patients. Therefore, the investigation of novel kidney injury biomarkers in these tropical diseases is of utmost importance to explain the mechanisms of kidney injury, to improve their diagnosis and prognosis, as well as the assessment to health systems by these patients. Since 2011, our group has been studying renal biomarkers in visceral and cutaneous leishmaniasis, schistosomiasis, leptospirosis and leprosy. This study has increased the knowledge on the pathophysiology of kidney disease in the presence of these infections and has contributed to the early diagnosis of kidney injury, pointing to glomerular, endothelial and inflammatory involvement as the main causes of the mechanisms leading to nephropathy and clinical complications. Future perspectives comprise establishing long-term cohort groups to assess the development of kidney disease and the patients' survival, as well as the use of new biomarkers such as urinary exosomes to detect risk groups and to understand the progression of kidney injuries.

Malarial Hepatopathy in Children Visiting a Tertiary Healthcare Hospital in Karachi

Objective To determine the frequency of malarial hepatopathy in children that are visiting Lyari General Hospital in Karachi, Pakistan. Study design Cross sectional descriptive study. Material and methods Patients with age between two months and 15 years, who had positive blood film for Plasmodium falciparum or P. vivax, were included in the study. All patients were monitored for malarial hepatopathy. Result A total of 241 cases were included in the study. Mean age at admission was 4.1 ± 1.3 years and male to female ratio was 1.2:1. There were 133 (55.2%) cases of P. vivax, while 108 (44.8%) were of P. falciparum. Malarial hepatopathy was observed in 37 patients (15.4%). Malaria hepatopathy was present in 24.1% and 8.3% children having P. falciparum and P. vivax, respectively. Malaria hepatopathy was present in 24%, 18% and 6% in age groups two months to five years, >5 years to 10 years and >10 years, respectively. Conclusion Malarial hepatopathy was observed in about one-sixth of study population and it was more common between two months and five years age group.

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.

Kidney involvement in malaria: an update

Malaria is an infectious disease of great importance for Public Health, as it is the most prevalent endemic disease in the world, affecting millions of people living in tropical areas of the globe. Kidney involvement is relatively frequent in infections by P. falciparum and P. malariae, but has also been described in the infection by P. vivax. Kidney complications in malaria mainly occur due to hemodynamic dysfunction and immune response. Liver complications leading to hepatomegaly, jaundice and hepatic dysfunction can also contribute to the occurrence of acute kidney injury. Histologic studies in malaria also evidence glomerulonephritis, acute tubular necrosis and acute interstitial nephritis. It is also possible to find chronic kidney disease associated with malaria, mainly in those patients suffering from repeated episodes of infection. Plasmodium antigens have already been detected in the glomeruli, suggesting a direct effect of the parasite in the kidney, which can trigger an inflammatory process leading to different types of glomerulonephritis. Clinical manifestations of kidney involvement in malaria include proteinuria, microalbuminuria and urinary casts, reported in 20 to 50% of cases. Nephrotic syndrome has also been described in the infection by P. falciparum, but it is rare. This paper highlights the main aspects of kidney involvement in malaria and important findings of the most recent research addressing this issue.

The clinical and biochemical features of complicated falciparum malarial nephropathy

Objective

This study aimed to explore renal involvement in complicated falciparum malaria as observed in hospitalized children.

Methods

This prospective study was conducted for four consecutive years with children 6 months to 14 years old who were affected by malarial nephropathy. Malaria was confirmed by microscopic examination of a blood smear. Detailed clinical evaluation and investigations were carried out to determine multi-organ involvement with special emphasis on renal functions. The staging for Acute Kidney Injury (AKI) was carried out as per Acute Kidney Injury Network Staging, which provided three groups of patients who were further modified by Risk, Injury, Failure, Loss, End stage renal disease (RIFLE) staging.

Results

Out of 350 cases with malaria, 56 (16%) cases had nephropathy. One-hundred-forty cases (40%) were aged between 5 and 10 years. Serious renal involvement was observed in 14 (25%) children who were 10-14 years old. Oligo-anuria was found in 40 (71.4%) cases, and generalized oedema was found in 33 (58.9%) children from the onset of malaria. Approximately 47 cases showed associated multi-organ dysfunction, and 9 cases had isolated renal failure. Malaria-induced hepatopathy and nephropathy had a higher risk of death than nephropathy alone.

Conclusion

The spectrum of malarial nephropathy in children is highly variable, ranging from asymptomatic proteinuria to advanced stages of AKI. Renal involvement is more common and severe in P. falciparum. Children aged between 5 and 14 years and those with oligo-anuria, symptomatic azotaemia, electrolyte abnormalities and hepatopathy are more likely to develop advanced stage AKI and subsequently have an increased risk of mortality.

Delayed Diagnosis of Falciparum Malaria with Acute Kidney Injury

Prompt malaria diagnosis is crucial so antimalarial drugs and supportive care can then be rapidly initiated. A 15-year-old boy who had traveled to Africa (South Africa, Kenya, and Nigeria between January 3 and 25, 2011) presented with fever persisting over 5 days, headache, diarrhea, and dysuria, approximately 17 days after his return from the journey. Urinalysis showed pyuria and hematuria. Blood examination showed hemolytic anemia, thrombocytopenia, disseminated intravascular coagulation, and hyperbilirubinemia. Plasmapheresis and hemodialysis were performed for 19 hospital days. Falciparum malaria was then confirmed by peripheral blood smear, and antimalarial medications were initiated. The patient's condition and laboratory results were quickly normalized. We report a case of severe acute renal failure associated with delayed diagnosis of falciparum malaria, and primary use of supportive treatment rather than antimalarial medicine. The present case suggests that early diagnosis and treatment is important because untreated tropical malaria can be associated with severe acute renal failure and fatality. Physicians must be alert for correct diagnosis and proper management of imported tropical malaria when patients have travel history of endemic areas.

Depletion of Phagocytic Cells during Nonlethal Plasmodium yoelii Infection Causes Severe Malaria Characterized by Acute Renal Failure in Mice

In the current study, we examined the effects of depletion of phagocytes on the progression of Plasmodium yoelii 17XNL infection in mice. Strikingly, the depletion of phagocytic cells, including macrophages, with clodronate in the acute phase of infection significantly reduced peripheral parasitemia but increased mortality. Moribund mice displayed severe pathological damage, including coagulative necrosis in liver and thrombi in the glomeruli, fibrin deposition, and tubular necrosis in kidney. The severity of infection was coincident with the increased sequestration of parasitized erythrocytes, the systematic upregulation of inflammation and coagulation, and the disruption of endothelial integrity in the liver and kidney. Aspirin was administered to the mice to minimize the risk of excessive activation of the coagulation response and fibrin deposition in the renal tissue. Interestingly, treatment with aspirin reduced the parasite burden and pathological lesions in the renal tissue and improved survival of phagocyte-depleted mice. Our data imply that the depletion of phagocytic cells, including macrophages, in the acute phase of infection increases the severity of malarial infection, typified by multiorgan failure and high mortality.

Infectious Diseases and the Kidney in Children

The kidney is involved in a wide range of bacterial, viral, fungal, and parasitic diseases. In most systemic infections, renal involvement is a minor component of the illness, but in some, renal failure may be the presenting feature and the major problem in management. Although individual infectious processes may have a predilection to involve the renal vasculature, glomeruli, interstitium, or collecting systems, a purely anatomic approach to the classification of infectious diseases affecting the kidney is rarely helpful because most infections may involve several different aspects of renal function. In this chapter, a microbiological classification of the organisms affecting the kidney is adopted. Although they are important causes of renal dysfunction in infectious diseases, urinary tract infections and hemolytic uremic syndrome (HUS) are not discussed in detail because they are considered separately in chapters XX and XX, respectively.

Why the communicable/non-communicable disease dichotomy is problematic for public health control strategies: implications of multimorbidity for health systems in an era of health transition

In today's globalized world, rapid urbanization, mechanization of the rural economy, and the activities of trans-national food, drink and tobacco corporations are associated with behavioral changes that increase the risk of chronic non-communicable diseases (NCDs). These changes include less healthy diet, lower physical activity, tobacco smoking and increased alcohol consumption. As a result, population health profiles are rapidly changing. For example, the global burden of type 2 diabetes mellitus is expected to double by 2030, with 80% of adult cases occurring in low and middle-income countries (LMIC). Many LMIC are undergoing rapid changes associated with developing high rates of NCD while concomitantly battling high levels of certain communicable diseases, including HIV, TB and malaria. This has population health, health systems and economic implications for these countries. This critical review synthesizes evidence on the overlap and interactions between established communicable and emerging NCD epidemics in LMIC. The review focuses on HIV, TB and malaria and explores the disease-specific interactions with prevalent NCDs in LMIC including diabetes, cardiovascular disease, chronic obstructive pulmonary disease, chronic renal disease, epilepsy and neurocognitive diseases. We highlight the complexity, bi-directionality and heterogeneity of these interactions and discuss the implications for health systems.

Protective Effect of Aqueous Crude Extract of Neem (Azadirachta indica) Leaves on Plasmodium berghei-Induced Renal Damage in Mice

Malaria is a major public health problem in the world because it can cause of death in patients. Malaria-associated renal injury is associated with 45% of mortality in adult patients hospitalized with severe form of the disease. Therefore, new plant extracts to protect against renal injury induced by malaria infection are urgently needed. In this study, we investigated the protective effect of aqueous crude extract of Azadirachta indica (neem) leaves on renal injury induced by Plasmodium berghei ANKA infection in mice. ICR mice were injected intraperitoneally with 1 × 10⁷ parasitized erythrocytes of PbANKA, and neem extracts (500, 1,000, and 2,000 mg/kg) were given orally for 4 consecutive days. Plasma blood urea nitrogen (BUN) and creatinine levels were subsequently measured. Malaria-induced renal injury was evidenced as marked increases of BUN and creatinine levels. However, the oral administration of neem leaf extract to PbANKA infected mice for 4 days brought back BUN and creatinine levels to near normalcy, and the highest activity was observed at doses of 1,000 and 2,000 mg/kg. Additionally, no toxic effects were found in normal mice treated with this extract. Hence, neem leaf extract can be considered a potential candidate for protection against renal injury induced by malaria.

Genome-wide identification and functional annotation of Plasmodium falciparum long noncoding RNAs from RNA-seq data

The life cycle of Plasmodium falciparum is very complex, with an erythrocytic stage that involves the invasion of red blood cells and the survival and growth of the parasite within the host. Over the past several decades, numbers of studies have shown that proteins exported by P. falciparum to the surface of infected red blood cells play a critical role in recognition and interaction with host receptors and are thus essential for the completion of the life cycle of P. falciparum. However, little is known about long noncoding RNAs (lncRNAs). In this study, we designed a computational pipeline to identify new lncRNAs of P. falciparum from published RNA-seq data and analyzed their sequences and expression features. As a result, 164 novel lncRNAs were found. The sequences and expression features of P. falciparum lncRNAs were similar to those of humans and mice: there was a lack of sequence conservation, low expression levels, and high expression coefficient of variance and co-expression with nearby coding sequences in the genome. Next, a coding/noncoding gene co-expression network for P. falciparum was constructed to further annotate the functions of novel and known lncRNAs. In total, the functions of 69 lncRNAs, including 44 novel lncRNAs, were annotated. The main functions of the lncRNAs included metabolic processes, biosynthetic processes, regulation of biological processes, establishment of localization, catabolic processes, cellular component organization, and interspecies interactions between organisms. Our results will provide clues to further the investigation of interactions between human hosts and parasites and the mechanisms of P. falciparum infection.

Plasmodium vivax malaria associated with acute post infectious glomerulonephritis

Malaria remains a major health problem in many parts of the world leading to high morbidity and mortality related to renal dysfunction and relapsing nature of Plasmodium vivax malaria. Acute renal failure occurs commonly in Plasmodium falciparum malaria, although its rare occurrences have been reported in P. vivax malaria also. We reported a rare case of P. vivax malaria monoinfection associated with acute post infectious glomerulonephritis.

Malaria inhibits surface expression of complement receptor 1 in monocytes/macrophages, causing decreased immune complex internalization

Complement receptor 1 (CR1) expressed on the surface of phagocytic cells binds complement-bound immune complexes (IC), playing an important role in the clearance of circulating IC. This receptor is critical to prevent accumulation of IC, which can contribute to inflammatory pathology. Accumulation of circulating IC is frequently observed during malaria, although the factors contributing to this accumulation are not clearly understood. We have observed that the surface expression of CR1 on monocytes/macrophages and B cells is strongly reduced in mice infected with Plasmodium yoelii, a rodent malaria model. Monocytes/macrophages from these infected mice present a specific inhibition of complement-mediated internalization of IC caused by the decreased CR1 expression. Accordingly, mice show accumulation of circulating IC and deposition of IC in the kidneys that inversely correlate with the decrease in CR1 surface expression. Our results indicate that malaria induces a significant decrease on surface CR1 expression in the monocyte/macrophage population that results in deficient internalization of IC by monocytes/macrophages. To determine whether this phenomenon is found in human malaria patients, we have analyzed 92 patients infected with either P. falciparum (22 patients) or P. vivax (70 patients) , the most prevalent human malaria parasites. The levels of surface CR1 on peripheral monocytes/macrophages and B cells of these patients show a significant decrease compared with uninfected control individuals in the same area. We propose that this decrease in CR1 plays an essential role in impaired IC clearance during malaria.

Blackwater fever like in murine malaria

Blackwater fever (BWF) is the term used to designate the occurrence of hemoglobin pigments in the urine of patients infected with malaria parasites. BWF is more often associated with Plasmodium falciparum infection in man. The pathogenesis of BWF has not been explained satisfactorily. In the present study, the clinical and pathological observations made upon CD1 mice infected with Plasmodium yoelii yoelii lethal strain with clinical signs of hemoglobinuria and acute renal failure were evaluated. From the 40 P. yoelii yoelii-infected mice, 14 presented hemoglobinuria. In the observations, it was emphasized that hemoglobinuria occurred in the animals 1-2 days before they die. At 6 days post-infection, infected hemoglobinuric mice (HM) exhibited clinical signs such as dark red urine, apnea, and evident oliguria and hematuria; urine microscopical examination showed very few red blood cells. The entire non hemoglobinuric infected mice had a high parasitemia preceding the time of death, while the HM parasitemia was just detectable. In HM, marked hepatosplenomegaly, anemia, and renal and hepatic dysfunction were observed with the blood chemistry analysis at 6 days post-infection. Severe renal lesions were demonstrated in histopathological and scanning electron microscopy samples. Occlusion and necrosis of convoluted tubules were the main lesions found. The conditions required for the experimental production of hemoglobinuria in CD1 mouse infected by P. yoelii yoelii is still unknown. The clinical picture of a BWF, like in our rodents, was produced exclusively by the interaction between the parasite and its host. Results showed that hemoglobinuria in CD1 mice infected with P. yoelii yoelii and BWF in man infected with P. falciparum are similar in their pathogenesis.

Postrenal transplant Plasmodium vivax malaria: neglected and not benign

Plasmodium vivax is causing increasingly more cases of severe malaria worldwide. We reported a case of postrenal transplantation acute kidney injury (AKI) associated with P. vivax, a neglected human malaria parasite. The diagnosis of P. vivax monoinfection was confirmed by direct visualization of the parasite in blood smear and rapid diagnostic test. On admission, serum creatinine (SCr.) increased from 1.45 to 3.7 mg/dl. The other etiologies of fever and AKI were ruled out. He responded to prompt therapy with antimalarial drugs. There was no change in tacrolimus trough level before and after antimalarial drugs. Two weeks after discharge, his SCr. was 1.43 mg/dl. Our patient lived in an endemic malarial area and the transplant took place in December 2010. The patient subsequently presented with clinical malaria in June 2012, so we thought that posttransplantation transmission by the mosquito was a possibility and very less likely that other dormant form of the parasite had been the source of the clinical infection. P. vivax can lead to as AKI in renal transplant recipient. P. vivax should be considered in the differential diagnosis of fever in transplant recipients who had received organs or blood products from malaria-endemic area to facilitate a prompt diagnosis and adequate treatment.

Pathogenesis of malaria in tissues and blood

The clinical manifestations of severe malaria are several and occur in different anatomical sites. Both parasite- and host-related factors contribute to the pathogenicity of the severe forms of the disease. Cytoadherence of infected red blood cells to the vascular endothelium of different organs and rosetting are unique features of malaria parasites which are likely to contribute to the vascular damage and the consequent excessive inflammatory/immune response of the host. In addition to cerebral malaria or severe anaemia, which are quite common manifestation of severe malaria, clinical evidences of thrombocytopenia, acute respiratory distress syndrome (ARDS), liver and kidney disease, are reported. In primigravidae from endemic areas, life threatening placental malaria may also be present.

In the following pages, some of the pathogenetic aspects will be briefly reviewed and then data on selected and less frequent manifestation of severe malaria, such as liver or renal failure or ARDS will be discussed.

Collapsing glomerulopathy and hemolytic uremic syndrome associated with falciparum malaria: completely reversible acute kidney injury

Acute kidney injury (AKI) is one of the most dreaded complications of severe malaria. Herein, we report a case of spontaneous resolution of AKI due to collapsing glomerulopathy (CG) and hemolytic-uremic syndrome (HUS) associated with P. falciparum malaria. Our case report highlights the fact that early intervention on the triggering cause of CG without a long course of steroids may obtain a remission of this severe subset of CG and may obtain a remission of HUS without therapeutic plasmapheresis The etiologic treatment of CG and HUS may avoid progression to end-stage renal disease.

Redox-active antiparasitic drugs

SIGNIFICANCE

Parasitic diseases affect hundreds of millions of people worldwide and represent major health problems. Treatment is becoming extremely difficult due to the emergence of drug resistance, the absence of effective vaccines, and the spread of insecticide-resistant vectors. Thus, identification of affordable and readily available drugs against resistant parasites is of global demand.

RECENT ADVANCES

Susceptibility of many parasites to oxidative stress is a well-known phenomenon. Therefore, generation of reactive oxygen species (ROS) or inhibition of endogenous antioxidant enzymes would be a novel therapeutic approach to develop antiparasitic drugs. This article highlights the unique metabolic pathways along with redox enzymes of unicellular (Plasmodium falciparum, Trypanosoma cruzi, Trypanosoma brucei, Leishmania donovani, Entamoeba histolytica, and Trichomonas vaginalis) and multicellular parasites (Schistosoma mansoni), which could be utilized to promote ROS-mediated toxicity.

CRITICAL ISSUES

Enzymes involved in various vital redox reactions could be potential targets for drug development.

FUTURE DIRECTIONS

The identification of redox-active antiparasitic drugs along with their mode of action will help researchers around the world in designing novel drugs in the future.

Monoclonal auto-antibodies and sera of autoimmune patients react with Plasmodium falciparum and inhibit its in vitro growth

The relationship between autoimmunity and malaria is not well understood. To determine whether autoimmune responses have a protective role during malaria, we studied the pattern of reactivity to plasmodial antigens of sera from 93 patients with 14 different autoimmune diseases (AID) who were not previously exposed to malaria. Sera from patients with 13 different AID reacted against Plasmodium falciparum by indirect fluorescent antibody test with frequencies varying from 33-100%. In addition, sera from 37 AID patients were tested for reactivity against Plasmodium yoelii 17XNL and the asexual blood stage forms of three different P. falciparum strains. In general, the frequency of reactive sera was higher against young trophozoites than schizonts (p < 0.05 for 2 strains), indicating that the antigenic determinants targeted by the tested AID sera might be more highly expressed by the former stage. The ability of monoclonal auto-antibodies (auto-Ab) to inhibit P. falciparum growth in vitro was also tested. Thirteen of the 18 monoclonal auto-Ab tested (72%), but none of the control monoclonal antibodies, inhibited parasite growth, in some cases by greater than 40%. We conclude that autoimmune responses mediated by auto-Ab may present anti-plasmodial activity.

Population dynamics of a pathogen: the conundrum of vivax malaria

Building a mathematical model of population dynamics of pathogens within their host involves considerations of factors similar to those in ecology, as pathogens can prey on cells in the host. But within the multicellular host, attacked cell types are integrated with other cellular systems, which in turn intervene in the infection. For example, immune responses attempt to sense and then eliminate or contain pathogens, and homeostatic mechanisms try to compensate for cell loss. This review focuses on modeling applied to malarias, diseases caused by single-cell eukaryote parasites that infect red blood cells, with special concern given to vivax malaria, a disease often thought to be benign (if sometimes incapacitating) because the parasite only attacks a small proportion of red blood cells, the very youngest ones. However, I will use mathematical modeling to argue that depletion of this pool of red blood cells can be disastrous to the host if growth of the parasite is not vigorously check by host immune responses. Also, modeling can elucidate aspects of new field observations that indicate that vivax malaria is more dangerous than previously thought.

A lethal case of Plasmodium falciparum infection in a young patient with end-stage renal failure who underwent regular hemodialysis

Acute renal failure associated with Plasmodium falciparum infection is already well recognized. Nevertheless, end-stage chronic renal failure and falciparum malaria comorbidity is a rare condition. We report a case of Plasmodium falciparum infection in a young male Javanese patient with end-stage chronic renal failure who underwent regular hemodialysis. This rare comorbidity led to rapid deterioration of consciousness and metabolic disturbances which had already existed in end-stage renal failure. Because of the immunosuppressive condition due to organ failure, the patient did not survive despite anti-malarial chemotherapy.

Clinical and laboratory features of human Plasmodium knowlesi infection

BACKGROUND

Plasmodium knowlesi is increasingly recognized as a cause of human malaria in Southeast Asia but there are no detailed prospective clinical studies of naturally acquired infections.

METHODS

In a systematic study of the presentation and course of patients with acute P. knowlesi infection, clinical and laboratory data were collected from previously untreated, nonpregnant adults admitted to the hospital with polymerase chain reaction-confirmed acute malaria at Kapit Hospital (Sarawak, Malaysia) from July 2006 through February 2008.

RESULTS

Of 152 patients recruited, 107 (70%) had P. knowlesi infection, 24 (16%) had Plasmodium falciparum infection, and 21 (14%) had Plasmodium vivax. Patients with P. knowlesi infection presented with a nonspecific febrile illness, had a baseline median parasitemia value at hospital admission of 1387 parasites/microL (interquartile range, 6-222,570 parasites/microL), and all were thrombocytopenic at hospital admission or on the following day. Most (93.5%) of the patients with P. knowlesi infection had uncomplicated malaria that responded to chloroquine and primaquine treatment. Based on World Health Organization criteria for falciparum malaria, 7 patients with P. knowlesi infection (6.5%) had severe infections at hospital admission. The most frequent complication was respiratory distress, which was present at hospital admission in 4 patients and developed after admission in an additional 3 patients. P. knowlesi parasitemia at hospital admission was an independent determinant of respiratory distress, as were serum creatinine level, serum bilirubin, and platelet count at admission (p < .002 for each). Two patients with knowlesi malaria died, representing a case fatality rate of 1.8% (95% confidence interval, 0.2%-6.6%).

CONCLUSIONS

Knowlesi malaria causes a wide spectrum of disease. Most cases are uncomplicated and respond promptly to treatment, but approximately 1 in 10 patients develop potentially fatal complications.

[Recommendations before travelling for renal transplant patients]

Travel is now a reasonable objective of CKD patients after renal transplantation. However, immunosuppressive treatment makes them particularly susceptible to infections and may interfere with vaccinations and other drugs. Travel in countries with low health level should be strongly discouraged in the first six months after transplantation or following an acute event. Otherwise, specific consultations should be arranged to prepare the patient as soon as possible. Vaccinations should be started early before departure. Specific immunisations include vaccines against hepatitis A, typhoid, meningococcus and rabies in some cases. Living vaccines are formally contra-indicated. Particular attention should be paid for protection against insects because this is the only effective measure against diseases. In the case of malaria, it should be complemented by adapted chemoprophylaxis that should be started 15 days before the departure date. Advice on hygiene measures should be clarified because this can prevent numerous infections, especially of the digestive tract. Advice on the management of diarrhoea is essential, especially in terms of preventing dehydration. Finally, advice about transport and physical risks, especially those related to sun exposure, should also be addressed.

Malarial infection develops mitochondrial pathology and mitochondrial oxidative stress to promote hepatocyte apoptosis

Activation of the mitochondrial apoptosis pathway by oxidative stress has been implicated in hepatocyte apoptosis during malaria. Because mitochondria are the source and target of reactive oxygen species (ROS), we have investigated whether hepatocyte apoptosis is linked to mitochondrial pathology and mitochondrial ROS generation during malaria. Malarial infection induces mitochondrial pathology by inhibiting mitochondrial respiration, dehydrogenases, and transmembrane potential and damaging the ultrastructure as evident from transmission electron microscopic studies. Mitochondrial GSH depletion and formation of protein carbonyl indicate that mitochondrial pathology is associated with mitochondrial oxidative stress. Fluorescence imaging of hepatocytes documents intramitochondrial superoxide anion (O(2)(-)) generation during malaria. O(2)(-) inactivates mitochondrial aconitase to release iron from iron-sulfur clusters, which forms the hydroxyl radical ((.)OH) interacting with H(2)O(2) produced concurrently. Malarial infection inactivates mitochondrial aconitase, and carbonylation of aconitase is evident from Western immunoblotting. The release of iron has been documented by fluorescence imaging of hepatocytes using Phen Green SK, and mitochondrial (.)OH generation has been confirmed. During malaria, the depletion of cardiolipin and formation of the mitochondrial permeability transition pore favor cytochrome c release to activate caspase-9. Interestingly, mitochondrial (.)OH generation correlates with the activation of both caspase-9 and caspase-3 with the progress of malarial infection, indicating the critical role of (.)OH.