Renal function in acute falciparum malaria

Acute Kidney Injuries in Children with Severe Malaria: A comparative study of diagnostic criteria based on serum cystatin C and creatinine levels

Objectives

Serum creatinine levels are often used to diagnose acute kidney injury (AKI), but may not necessarily accurately reflect changes in glomerular filtration rate (GFR). This study aimed to compare the prevalence of AKI in children with severe malaria using diagnostic criteria based on creatinine values in contrast to cystatin C.

Methods

This prospective cross-sectional study was performed between June 2016 and May 2017 at the University of Ilorin Teaching Hospital, Ilorin, Nigeria. A total of 170 children aged 0.5–14 years old with severe malaria were included. Serum cystatin C levels were determined using a particle-enhanced immunoturbidmetric assay method, while creatinine levels were measured using the Jaffe reaction. Renal function assessed using cystatin C-derived estimated GFR (eGFR) was compared to that measured using three sets of criteria based on creatinine values including the Kidney Disease: Improved Global Outcomes (KDIGO) and World Health Organization (WHO) criteria as well as an absolute creatinine cut-off value of >1.5 mg/dL.

Results

Mean serum cystatin C and creatinine levels were 1.77 ± 1.37 mg/L and 1.23 ± 1.80 mg/dL, respectively (P = 0.002). According to the KDIGO, WHO and absolute creatinine criteria, the frequency of AKI was 32.4%, 7.6% and 16.5%, respectively. In contrast, the incidence of AKI based on cystatin C-derived eGFR was 51.8%. Overall, the rate of detection of AKI was significantly higher using cystatin C compared to the KDIGO, WHO and absolute creatinine criteria (P = 0.003, <0.001 and <0.001, respectively).

Conclusion

Diagnostic criteria for AKI based on creatinine values may not indicate the actual burden of disease in children with severe malaria.

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.

Urinalysis and Clinical Correlations in Patients with P. vivax or P. falciparum Malaria from Colombia

BACKGROUND

Urinalysis is a poorly reviewed diagnostic tool in malaria patients; its application can show the presence of severe malaria.

METHODS

Urinalysis was performed in a total of 620 patients diagnosed with malaria by thick blood smear; complications were classified according to WHO major criteria for severity and minor criteria according to the Colombian malaria guideline.

RESULTS

Severe or moderate clinical complications were diagnosed in 31.1% of patients, hepatic dysfunctions were diagnosed in 25.8%, anemia was diagnosed in 9.8%, thrombocytopenia was diagnosed in 7.7%, renal dysfunction was diagnosed in 4.8%, neurological and pulmonary complications were diagnosed in 2.1% and 2.4%, hypoglycemia was diagnosed in 1.1% of patients with blood glucose analysis, and acidosis was diagnosed in 10 of 25. Bilirubinuria was found in 24.3%, associated with urobilinuria, proteinuria, and increased specific gravity; urobilinuria was found in 30.6% associated with elevated serum bilirubin and alanine aminotransferase; 39.2% had proteinuria, associated with higher blood urea nitrogen, serum bilirubin, aspartate, alanine-transaminase, hematuria, and increased specific gravity. Severe or moderate liver and renal complications were associated with proteinuria and bilirubinuria. Urobilinuria was associated with thrombocytopenia and neurological and hepatic dysfunction. Ketonuria was associated with neurological dysfunctions.

CONCLUSIONS

The most frequent alterations in the urinalysis were bilirubinuria, proteinuria, urobilinuria, and increased specific gravity, related to thrombocytopenia and liver, kidney, and neurological alterations.

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.

Metabolic perturbations of kidney and spleen in murine cerebral malaria: (1)H NMR-based metabolomic study

A significant fraction of global population is under the threat of malaria. Majority of annual death is due to the more complicated form of the infection i.e. the cerebral form, also known as Cerebral Malaria (CM). Host parasite interaction is known to cause a cascade of events in various tissues like brain, liver, kidney, and spleen. We have employed (1)H NMR based metabolomics to understand the specific perturbations of various tissues in CM. In our previous paper we have delineated the differences between CM vis-a-vis non-cerebral malaria (NCM) mice in serum, liver and brain. In this paper we focus on their differences of metabolic profile in kidney and spleen as kidney dysfunction and splenomegaly are known to be associated to neurological outcome of the disease. Moreover we have also looked into how the biological compartments (kidney, spleen and serum) interact with each other. The various metabolites involved in such interactions and their correlational aspects across the compartments have been studied in CM, NCM and control mice. The idea was to find out the specific pathways that are altered in CM mice. Our results demonstrate that both the kidney as well as spleen metabolism are differentially perturbed in CM with respect to NCM. The results point out that glutamate levels are decreased in CM mice with respect to NCM mice both in case of spleen and kidney while creatine, myo-inositol and betaine levels are increased in kidney of CM mice with respect to NCM mice. From the analysis of Multiway Principal Component Analysis (MPCA) we see that lipid metabolism and TCA cycle is altered in kidney and spleen.

Unusual presentations of malaria in children: an experience from a tertiary care center in North East India

OBJECTIVE

To identify cases of malaria with unusual presentations.

METHODS

The medical record of all the cases of malaria admitted to PICU and pediatric general ward from Oct 2006 to Sep 2009, were reviewed and cases with unusual presentations were identified. The study design was retrospective descriptive study.

RESULTS

Sixteen (10%) out of 162 malaria cases had unusual presentations - three had hemiplegia, two each with viral hepatitis-like presentation, acute abdomen, gastrointestinal bleed, generalized edema and hyperglycemia and one each with ptosis, severe headache and subacute intestinal obstruction-like presentation. Eleven cases had mixed parasitemia and two each with P. vivax and P. falciparum. One case was diagnosed on clinical grounds.

CONCLUSION

Malaria is a common disease, but both typical and atypical presentations deserve attention for early diagnosis and management.

Randomised trial of artemether versus artemether and mefloquine for the treatment of chloroquine/sufadoxine-pyrimethamine-resistant falciparum malaria during pregnancy

The efficacy of artemether and artemether followed by mefloquine was evaluated in 45 pregnant women with drug resistant Plasmodium falciparum malaria during the second and third trimesters. There was prompt clinical response to both treatment regimens. The parasite and fever clearance times and the cure rate were similar in both groups. Except for the correlation between initial parasite density and fever clearance time in the artemether-mefloquine group, there was no correlation between initial parasite density and parasite or fever clearance times in the two groups. Similarly, there was no correlation between parasite and fever clearance. Both treatment regimens were well tolerated. All newborn babies of the participating women were normal at birth. Physical and neurodevelopmental assessment of the newborn babies followed up for a period varying between 6 and 36 months were within normal limits. Artemether alone or with mefloquine are effective and do not produce undue deleterious effects in pregnant patients with drug-resistant falciparum malaria during the second and third trimesters.

Hyponatremia in severe malaria: evidence for an appropriate anti-diuretic hormone response to hypovolemia

Although hyponatremia occurs in most patients with severe malaria, its pathogenesis, prognostic significance, and optimal management have not been established. Clinical and biochemical data were prospectively collected from 171 consecutive Bangladeshi adults with severe malaria. On admission, 57% of patients were hyponatremic. Plasma sodium and Glasgow Coma Score were inversely related (r_s = −0.36, P < 0.0001). Plasma antidiuretic hormone concentrations were similar in hyponatremic and normonatremic patients (median, range: 6.1, 2.3–85.3 versus 32.7, 3.0–56.4 pmol/L; P = 0.19). Mortality was lower in hyponatremic than normonatremic patients (31.6% versus 51.4%; odds ratio [95% confidence interval]: 0.44 [0.23–0.82]; P = 0.01 by univariate analysis). Plasma sodium normalized with crystalloid rehydration from (median, range) 127 (123–140) mmol/L on admission to 136 (128–149) mmol/L at 24 hours (P = 0.01). Hyponatremia in adults with severe malaria is common and associated with preserved consciousness and decreased mortality. It likely reflects continued oral hypotonic fluid intake in the setting of hypovolemia and requires no therapy beyond rehydration.

Mannitol as adjunct therapy for childhood cerebral malaria in Uganda: a randomized clinical trial

Background

Several reports have suggested that raised intracranial pressure (ICP) is a major contributor to death among children with cerebral malaria. Mannitol, an osmotic diuretic, effectively lowers ICP and is used to treat post-traumatic raised ICP. It is not clear whether intravenous mannitol given to children with cerebral malaria improves clinical outcome. The objective of this study was to determine the effect of mannitol as adjunct therapy on the clinical outcome of children with cerebral malaria.

Methods

This randomized double-blind placebo controlled clinical trial was carried out at the Emergency Paediatric ward of Mulago Hospital, Uganda's national referral and teaching hospital. One hundred and fifty six children aged 6 to 60 months with cerebral malaria were randomized to either one dose of mannitol 1 g/kg or placebo, in addition to intravenous quinine. Main outcome measures included coma recovery time; time to sit unsupported, begin oral intake; duration of hospitalization; death and adverse effects.

Results

Time to regain consciousness (p = 0.11), sit unsupported (p = 0.81), time to start oral intake (p = 0.13) and total coma duration (p = 0.07) were similar in both groups. There was no significant difference in the mortality between the placebo (13/80 or 16.3%) and mannitol (10/76 or 13.2%) groups: RR = 1.2 (CI 0.5–2.7). No adverse effects were observed after administration of mannitol.

Conclusion

Mannitol had no significant impact on clinical outcome of cerebral malaria. It is difficult to recommend intravenous mannitol as adjunct therapy for childhood cerebral malaria.

Clinical registration number

ClinicalTrials.gov ID: NCT00113854

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.

The effects of artemether-lumefantrine vs amodiaquine-sulfalene-pyrimethamine on the hepatomegaly associated with Plasmodium falciparum malaria in children

An open randomized controlled study of artemether-lumefantrine (AL) and amodiaquine-sulfalene-pyrimethamine (ASP) for the treatment of uncomplicated Plasmodium falciparum malaria was carried out in 181 children. In 79 children, the hepatomegaly reduction ratios (HRR) and the speed of resolution of hepatomegaly, the hepatomegaly resolution rates (HRSR), were calculated and compared between the two treatment groups. HRR and HRSR were similar in the two treatment groups. HRSR was 71% and 62% in AL- and ASP-treated children, respectively, 14 days after commencing treatment. There was no significant correlation between HRR and parasite reduction ratio in the same patient. In children in whom parasitaemia cleared and hepatomegaly resolved within 14 days, recurrence of parasitaemia was associated with reoccurrence of hepatomegaly, suggesting that the propensity for recurrence of infection drives the malaria-attributable hepatomegaly in children from this endemic area. Combination therapy may provide additional beneficial effects on pathophysiological processes and changes associated with falciparum malaria by rapid clearing of asexual parasitaemia and reducing the propensity for recurrence of infection.

Gametocyte sex ratios in children with asymptomatic, recrudescent, pyrimethamine-sulfadoxine-resistant, Plasmodium falciparum malaria

The clinical features of the primary Plasmodium falciparum infections in 25 children, and of the recrudescent infections that emerged after pyrimethamine-sulfadoxine (PS) treatment of the children had failed, were evaluated. In addition, the gametocyte sex ratios in these children and in age- and gender-matched controls who had PS-sensitive (PS-S) infections were also examined. Compared with the primary infections, the recrudescent infections were accompanied by significantly fewer symptoms and lower levels of parasitaemia but significantly higher gametocytaemia:parasitaemia ratios. Although the mean gametocyte sex ratio was female-biased pre-treatment, in both the PS-resistant (PS-R) and PS-S infections it became male-biased on days 7 and 14 post-treatment. The times taken to attain a sex ratio of 1 were similar in both groups. The predominance of macrogametocytes seen 'early' post-treatment (on day 3) was later replaced by a predominance of microgametocytes (on days 7 and 14). Analysis of the disposition of gametocytaemia, from the time to attain a sex ratio of 1, showed that the area under the curve of the plot of the level of microgametocytaemia upsilon. time and the mean half-life of the microgametocytaemia were significantly greater and microgametocytaemia clearance was significantly slower than the corresponding values for macrogametocytaemia. Although sex ratios in Plasmodium may naturally become more male-biased as the infection progresses, it is possible that PS treatment may have contributed to the male-biased sex ratios observed post-treatment.

The pathophysiology of falciparum malaria

Falciparum malaria is a complex disease with no simple explanation, affecting organs where the parasite is rare as well as those organs where it is more common. We continue to argue that it can best be understood in terms of excessive stimulation of normally useful pathways mediated by inflammatory cytokines, the prototype being tumor necrosis factor (TNF). These pathways involve downstream mediators, such as nitric oxide (NO) that the host normally uses to control parasites, but which, when uncontrolled, have bioenergetic failure of patient tissues as their predictable end point. Falciparum malaria is no different from many other infectious diseases that are clinically confused with it. The sequestration of parasitized red blood cells, prominent in some tissues but absent in others with equal functional loss, exacerbates, but does not change, these overriding principles. Recent opportunities to stain a wide range of tissues from African pediatric cases of falciparum malaria and sepsis for the inducible NO synthase (iNOS) and migration inhibitory factor (MIF) have strengthened these arguments considerably. The recent demonstration of bioenergetic failure in tissue removed from sepsis patients being able to predict a fatal outcome fulfils a prediction of these principles, and it is plausible that this will be demonstrable in severe falciparum malaria. Understanding the disease caused by falciparum malaria at a molecular level requires an appreciation of the universality of poly(ADP-ribose) polymerase-1 (PARP-1) and Na(+)/K(+)-ATPase and the protean effects of activation by inflammation of the former that include inactivation of the latter.

Renal dysfunction in children with uncomplicated, Plasmodium falciparum malaria in Tamale, Ghana

In a study performed in Tamale, in the Northern region of Ghana, cystatin C, a new and sensitive indicator of the glomerular filtration rate (GFR), was used to estimate the frequency of renal dysfunction in 78 children with uncomplicated, Plasmodium falciparum malaria. The excretion in urine of albumin, immunoglobulin G and alpha1-microglobulin was also investigated. Plasma concentrations of cystatin C were found to be elevated in 17% of the children, indicating subclinical impairment of renal function. As most (85%) of the children had glomerular as well as tubular patterns of proteinuria, it appears that both glomerulonephritis and damage to tubular cells often occur in P. falciparum malaria.

Case report: severe acute symptomatic hyponatraemia in falciparum malaria

Hyponatraemia is a common finding in malaria, but rarely appears to be of clinical significance. We describe a case of acute, profound, hyponatraemia with confusion and convulsions developing in the context of seemingly uncomplicated Plasmodium falciparum malaria. We draw attention to this rarely reported and poorly documented life-threatening complication and review the limited literature on the subject.

ICU management of severe malaria

Malaria is very common in India. First step in management of malaria is to establish the diagnosis. It is established by using traditional smear or method like dipstick antigen captures assay which is simpler, accurate and doesn't require expertise. Next step is to look for signs and symptoms, which help cases of severe malaria should be admitted in intensive care unit (ICU) and antimalarial chemotherapy should be started through parenteral route. Complications like coma, anemia, renal failure, pulmonary edema, disseminated intravascular coagulation are not very uncommon. These complications should be anticipated and treated in time. There is no role of corticosteroids, mannitol in the treatment of cerebral edema. Therapeutic monitoring of severe malaria should involve quantitative estimation of parasite load.

Electrolyte derangement in cerebral malaria: a case for a more aggressive approach to the management of hyponatraemia

Although hyponatraemia has been consistently shown to occur in a large proportion of children with cerebral malaria, no statistical relationship has been established between the incidence of hyponatraemia and that of malaria-attributable mortality. However, hyponatraemia is not a benign state in other conditions (such as meningitis) or in surgical patients, and is likely to add to malarial deaths. The high mortality rate seen among cases of cerebral malaria, despite all efforts to curb it, therefore calls for a more aggressive approach to the management of hyponatraemia. Current methods for the administration of hypotonic saline and isotonic glucose solutions need review. In addition, children admitted with cerebral malaria should have their electrolyte status monitored to identify new or ongoing hyponatraemia. When hyponatraemia is discovered, it should be quickly and actively corrected.

Biochemical and haematological variables in Gambian children with cerebral malaria

Biochemical and haematological measurements were made in Gambian children who satisfied the criteria for the diagnosis of cerebral malaria over a 3-year period. Biochemical and haematological values were available for 388 and 624 children, respectively. Biochemical signs of renal and hepatic dysfunction were found and these may have contributed in a cumulative way to the high mortality seen in the study children. Cerebral involvement in children with cerebral malaria is only one, though the most important, manifestation of a multi-organ disease.

Renal involvement in Gambian children with cerebral or mild malaria

Kidney function was studied in 80 Gambian children with cerebral malaria, 73 children with mild malaria, and in 19 children with other febrile illnesses. Serum creatinine was measured, and the excretion in urine of immunoglobulin G, transferrin, albumin and alpha 1 microglobulin was determined. Twenty-five percent of children with cerebral malaria, and 4% of children with mild malaria had an elevated serum creatinine above 62 mumol/l. Increased urinary protein excretion was frequent: 53% of children with cerebral malaria had a glomerulo-tubular pattern of protein excretion, and 46% a tubular pattern. Median albuminuria was 68 mg/l in children with cerebral malaria, 18 mg/l in children with mild malaria, and 9 mg/l in febrile children with other diseases (P < 0.0001). There was no significant association between the proteinuria and height of fever or the degree of parasitaemia, and there was no significant association between death and signs of renal impairment. Renal involvement is common in children with malaria in The Gambia, with prerenal, glomerular, and tubulo-interstitial factors contributing. It is more pronounced in children with cerebral malaria than in those with mild malaria. However, renal dysfunction is relatively mild and does not indicate a worse prognosis.

Prognosis of malaria associated severe acute renal failure in children

Between January and December 1996, we observed 64 children (mean age 8.3 years range 4.2 to 11.2 years) who required dialysis for severe acute renal failure secondary to Falciparum Malaria. All received anti malarial therapy and other supportive therapy as well as peritoneal dialysis. Out of these 28 died (43.8%). The children who died (Group I) compared to those who survived (Group II) differed significantly in age (mean +/- SD) (7.2 +/- 1.3 years vs. 9.2 +/- 2.1 years P < 0.05), plasma creatinine at presentation (645 +/- 104 mumol/L vs. 438 +/- 87 mumol/L P < 0.05), plasma bilirubin (2.1 +/- 0.3 mg/dL vs. 1.2 +/- 0.2 mg/dL P > 0.02) systolic BP (50 +/- 11 mmHg vs. 90 +/- 12 mmHg P0 < 0.01), diastolic BP (20 +/- 4 mmHg vs. 60 +/- 9 mmHg P < .01) .Hb level 5.3 +/- 0.4 g/dL vs. 8 +/- 1.3 gm/dL P < .02), time from diagnosis to referral (5.3 +/- 1.3 days vs. 8.9 +/- 2.1 days P < .05) and urine output (200 +/- 49 mL/24 h vs. 600 mL +/- 131 mL P < .01). There was no significant difference in gender, alanine transaminase (ALT) level, degree of fever, plasma Na or plasma K. Diarrhea was present in 29% of the children who died and in only 11% of those who survived (P > 0.05) and splenomegaly was found in 3% and 18% respectively (PO > .05).

Comparative cardiac effects of halofantrine and chloroquine plus chlorpheniramine in children with acute uncomplicated falciparum malaria

The cardiac effects of halofantrine (HF) and chloroquine plus chlorpheniramine (CQ-CP), a histamine H1 antagonist which reverses chloroquine insensitivity in Plasmodium falciparum in vitro and in vivo, were assessed in 41 children with acute symptomatic uncomplicated P. falciparum malaria by electrocardiographic and clinical monitoring over a period of 14 days. In addition, the cardiac effects of chloroquine (CQ) alone and CQ-CP were compared in 10 age- and sex-matched children. HF produced a significantly higher proportion of abnormally prolonged P-R interval (8 abnormally prolonged out of 132 total P-R events) than CQ-CP (1 of 133 P-R events) (P = 0.03), but a similar proportion of prolonged Q-Tc interval to that of CQ-CP (46 of 149 versus 29 of 134 events, P = 0.07). Compared with pre-treatment Q-Tc, HF significantly prolonged this interval from 6 to 96 h post treatment with a maximum effect at 24 h after commencing HF treatment. CQ-CP by contrast produced significant changes in Q-Tc values from 6 to only 48 h with a maximum effect at 48 h. HF-induced Q-Tc prolongations were significantly higher than those of CQ-CP only at 24 h. The cardiac effects of CQ-CP were similar to those of CQ alone. Despite the electrocardiogram abnormalities, rhythm disturbance was rare and there was no clinical symptom in any of the treatment groups. Compared with HF, CQ-CP produced cardiac effects that were less severe and in fewer children with acute falciparum malaria. The addition of CP to CQ does not significantly amplify the cardiac effects of CQ in children with acute uncomplicated falciparum malaria.

The biological basis of malarial disease

In this review we summarise the arguments that inflammatory cytokines, triggered by material released from the parasite at schizogony (malarial toxin), might induce the illness and pathology seen in malaria. These pro-inflammatory cytokines can generate inducible nitric oxide synthase and cause nitric oxide to be released, as can low concentrations of malarial toxin itself provided interferon-gamma, which has only low activity in the absence of malarial toxin, is present. We suggest here that recently described hypermetabolic functions of these mediators provide a much more plausible explanation for malarial hyperlactataemia and hypoglycaemia, the chief prognostic indicators in falciparum malaria, than does hypoxia secondary to mechanical blockage of vessels by sequestering parasites, which is the dominant current theory. We also review the arguments that rationalise, through these mediators, the reversibility of the coma of cerebral malaria. Although not yet tested at a cellular level, the proposal that nitric oxide generated in cerebral vascular walls contributes to this coma continues to gather indirect support. In addition, new evidence incriminating nitric oxide in the mechanism of tolerance to endotoxin rationalises the raised nitric oxide generation seen in malarial tolerance.