Cerebral malaria owing to Plasmodium vivax: case report

Optimal balance of benefit versus risk for tafenoquine in the treatment of Plasmodium vivax malaria

A single 300 mg dose of tafenoquine (an 8-aminoquinoline), in combination with a standard 3-day course of chloroquine, is approved in several countries for the radical cure (prevention of relapse) of Plasmodium vivax malaria in patients aged ≥ 16 years. Despite this, questions have arisen on the optimal dose of tafenoquine. Before the availability of tafenoquine, a 3-day course of chloroquine in combination with the 8-aminoquinoline primaquine was the only effective radical cure for vivax malaria. The World Health Organization (WHO)-recommended standard regimen is 14 days of primaquine 0.25 mg/kg/day or 7 days of primaquine 0.5 mg/kg/day in most regions, or 14 days of primaquine 0.5 mg/kg/day in East Asia and Oceania, however the long treatment courses of 7 or 14 days may result in poor adherence and, therefore, low treatment efficacy. A single dose of tafenoquine 300 mg in combination with a 3-day course of chloroquine is an important advancement for the radical cure of vivax malaria in patients without glucose-6-phosphate dehydrogenase (G6PD) deficiency, as the use of a single-dose treatment will improve adherence. Selection of a single 300 mg dose of tafenoquine for the radical cure of P. vivax malaria was based on collective efficacy and safety data from 33 studies involving more than 4000 trial participants who received tafenoquine, including over 800 subjects who received the 300 mg single dose. The safety profile of single-dose tafenoquine 300 mg is similar to that of standard-dosage primaquine 0.25 mg/kg/day for 14 days. Both primaquine and tafenoquine can cause acute haemolytic anaemia in individuals with G6PD deficiency; severe haemolysis can lead to anaemia, kidney damage, and, in some cases, death. Therefore, relapse prevention using an 8-aminoquinoline must be balanced with the need to avoid clinical haemolysis associated with G6PD deficiency. To minimize this risk, the WHO recommends G6PD testing for all individuals before the administration of curative doses of 8-aminoquinolines. In this article, the authors review key efficacy and safety data from the pivotal trials of tafenoquine and argue that the currently approved dose represents a favourable benefit-risk profile.

A Retrospective Analysis of Outcome in Malaria Patients Admitted into a Multidisciplinary Intensive Care Unit of a Tertiary Care Teaching Hospital

Introduction:

Malaria is a significant public health problem with people worldwide at risk for the disease. It is a mosquito-borne disease causing high-grade fever, chills, and flu-like illness. The World Health Organization (WHO) recommends the case with severe malaria should be admitted in the intensive care unit (ICU). Severe malaria is a medical emergency and often managed in ICU with regard to the definition of hyperparasitemia. The WHO amended the criteria for definition of severe malaria in 2006, 2010, and 2015.

Methods:

All patients had a full workup for fever that included three smears for malarial parasites, serology for dengue, leptospirosis, scrub typhus, enteric fever, blood, urine, sputum or endotracheal cultures, and other tests as clinically indicated. A diagnosis was made when a patient is tested positive for malarial antigen with a rapid diagnostic test and other causes of fever excluded. Patients were treated with intravenous Artesunate along with enteral Doxycycline.

Results:

Of total patients, the vasopressor requirements being Dopamine (7.40%), nor adrenaline (7.40%) and vasopressin (3.70%). None received packed red blood cell transfusions, whereas 14.81% had platelet transfusions. 66.66% required Noninvasive ventilation, none required invasive mechanical ventilation (IMV) and both noninvasive and IMV. None of the patients had received hemodialysis. The mean duration of ICU and hospital stay was 4.14 and 6.26 days, respectively. No deaths were observed during the study period.

Conclusion:

In our study, we hereby conclude the incidence of clinical features is in agreement with other studies with no in-hospital mortality.

Neurological complications in patients with Plasmodium vivax malaria from Karachi, Pakistan

BACKGROUND

Malaria remains an endemic disease in Pakistan with an estimated healthcare burden of 1.6 million cases annually, with Plasmodium vivax accounting for 67% of reported cases. P. vivax is the most common species causing malaria outside of Africa, with approximately 13.8 million reported cases worldwide.

METHOD

We report a series of P. vivax cases with cerebral involvement that presented at Aga Khan University Hospital, Karachi, Pakistan.

RESULTS

The majority of the patients presented with high-grade fever accompanied by projectile vomiting and abnormal behaviour, seizures, shock and unconsciousness. Seven of 801 patients with P. vivax monoinfection presented or developed cerebral complications. P. vivax infections were diagnosed based on peripheral smears and rapid diagnostic testing.

CONCLUSION

P. vivax infection can lead to severe complications, although not with the frequency of Plasmodium falciparum infection. Current cases highlight an increasing trend of cerebral complications caused by P. vivax.

Sticking for a Cause: The Falciparum Malaria Parasites Cytoadherence Paradigm

After a successful invasion, malaria parasite Plasmodium falciparum extensively remodels the infected erythrocyte cellular architecture, conferring cytoadhesive properties to the infected erythrocytes. Cytoadherence plays a central role in the parasite's immune-escape mechanism, at the same time contributing to the pathogenesis of severe falciparum malaria. In this review, we discuss the cytoadhesive interactions between P. falciparum infected erythrocytes and various host cell types, and how these events are linked to malaria pathogenesis. We also highlight the limitations faced by studies attempting to correlate diversity in parasite ligands and host receptors with the development of severe malaria.

Minocycline prevents cerebral malaria, confers neuroprotection and increases survivability of mice during Plasmodium berghei ANKA infection

Cerebral malaria (CM) is a neurological complication arising due to Plasmodium falciparum or Plasmodium vivax infection. Minocycline, a semi-synthetic tetracycline, has been earlier reported to have a neuroprotective role in several neurodegenerative diseases. In this study, we investigated the effect of minocycline treatment on the survivability of mice during experimental cerebral malaria (ECM). The currently accepted mouse model, C57BL/6 mice infected with Plasmodium berghei ANKA, was used for the study. Infected mice were treated with an intra-peritoneal dose of minocycline hydrochloride, 45mg/kg daily for ten days that led to parasite clearance in blood, brain, liver and spleen on 7th day post-infection; and the mice survived until experiment ended (90days) without parasite recrudescence. Evans blue extravasation assay showed that blood-brain barrier integrity was maintained by minocycline. The tumor necrosis factor-alpha protein level and caspase activity, which is related to CM pathogenesis, was significantly reduced in the minocycline-treated group. Fluoro-Jade® C and hematoxylin-eosin staining of the brains of minocycline group revealed a decrease in degenerating neurons and absence of hemorrhages respectively. Minocycline treatment led to decrease in gene expressions of inflammatory mediators like interferon-gamma, CXCL10, CCL5, CCL2; receptors CXCR3 and CCR2; and hence decrease in T-cell-mediated cerebral inflammation. We also proved that this reduction in gene expressions is irrespective of the anti-parasitic property of minocycline. The distinct ability of minocycline to modulate gene expressions of CXCL10 and CXCR3 makes it effective than doxycycline, a tetracycline used as chemoprophylaxis. Our study shows that minocycline is highly effective in conferring neuroprotection during ECM.

Acute kidney injury in a shepherd with severe malaria: a case report

Malaria is one of the main reasons for outpatient consultation and hospitalization in Mauritania. Although four Plasmodium species, ie, Plasmodium (P.) falciparum, P. vivax, P. malariae, and P. ovale, cause malaria in Mauritania, recent data on their frequency is lacking. Since infections with P. falciparum generally result in serious disease, their identification is important. We report a case of oliguric renal injury associated with malaria in a 65-year-old shepherd. Clinical manifestations included anemia, oliguria, and elevated creatinine and urea. The rapid diagnostic test for malaria and microscopic examination of blood smears were positive for P. falciparum. On the basis of this, the patient was diagnosed as having acute kidney injury as a complication of severe malaria. The patient was treated for malaria with intravenous quinine for 4 days, followed by 3 days of oral treatment. Volume expansion, antipyretic treatment, and diuretics were administered. He also had two rounds of dialysis after which he partially recovered renal function. This outcome is not always the rule. Prognosis depends much on early diagnosis and appropriate supportive treatment.

Plasmodium vivax Malaria Presenting with Multifocal Hemorrhagic Brain Infarcts in a School-going Child

Cerebral malaria is a well-known complication of Plasmodium falciparum malaria. Over recent years, however, Plasmodium vivax also has been reported to cause cerebral malaria with or without co-infection with P. falciparum Here, we report a boy aged 10 years presenting with acute febrile encephalopathy with raised intracranial pressure to the emergency, who was later diagnosed to have P. vivax malaria. His neurological status improved gradually during 6 weeks of pediatric intensive care unit stay. We report this case to highlight the unusual radiologic findings in the patient, such as multifocal hemorrhagic infarcts in the brainstem, bilateral thalami, frontal cortex and basal ganglia, which have not been reported with P. vivax malaria.

Role of Serum Lactate and Malarial Retinopathy in Prognosis and Outcome of Falciparum and Vivax Cerebral Malaria: A Prospective Cohort Study in Adult Assamese Tribes

Introduction:

There is no comprehensive data or studies relating to clinical presentation and prognosis of cerebral malaria (CM) in the tribal settlements of Assam. High rates of transmission and deaths from complicated malaria guided us to conduct a prospective observational cohort study to evaluate the factors associated with poor outcome and prognosis in patients of CM.

Materials and Methods:

We admitted 112 patients to the Bandarpara and Damodarpur Tribal Health Centers (THCs) between 2011 and 2013 with a strict diagnosis of CM. We assessed the role of clinical, fundoscopy and laboratory findings (mainly lactic acid) in the immediate outcome in terms of death and recovery, duration of hospitalization, neurocognitive impairment, cranial nerve palsies and focal neurological deficit.

Results:

The case fatality rate of CM was 33.03% and the prevalence of residual neurological sequelae at discharge was 16.07%. These are significantly higher than the previous studies. The mortality rate and neurological complications rate in patients with retinal whitening was 38.46% and 23.07%, with vessel changes was 25% and 18.75%, with retinal hemorrhage was 55.55% and 11.11% and with hyperlactatemia was 53.85% and 18.46%, respectively. Three patients of papilledema alone died.

Conclusion:

Our study suggests a strong correlation between hyperlactatemia, retinal changes (whitening, vessel changes and hemorrhage) and depth and duration of coma with longer duration of hospitalization, increased mortality, neurological sequelae and death. Plasmodium vivax mono-infection as a cause of CM has been confirmed. Prognostic evaluation of CM is useful for judicious allocation of resources in the THC.

Clinical Profile and Prognostic Indicators in Adults Hospitalized with Severe Malaria Caused by Different Plasmodium Species

INTRODUCTION

Severe malaria remains a major cause of death and morbidity among adults in the Asiatic tropics. This study was planned to evaluate clinical profile and prognostic indicators of severe malaria in adults so as to improve insight into this highly prevalent disease.

MATERIALS AND METHODS

This prospective observational study was conducted on 60 confirmed cases of malaria. Cases were divided into two groups: (a) study group: suffering from severe malaria and (b) control group: no severe manifestations. All cases were thoroughly studied for clinical features, laboratory evaluation, and outcome. Prognostic evaluation was also done by different score systems.

RESULTS

In all, 40 cases suffer from severe malaria (study group), while 20 cases belong to the control group. The majority of our cases were males of age 21-40 years. The most common species of malaria in the study group was vivax (52.5%), followed by falciparum (25%) and mixed malaria species (22.5%). The clinical predictors for severe malaria were rural habitat, longer duration of fever, marked chills, tiredness, giddiness, nausea, vomiting, decreased urine output, jaundice, and altered sensorium. Extreme weakness (80%), jaundice (55%), renal failure (50%), and severe anemia (27.5%) were the most common presenting features in severe malaria. Two patients died of severe mixed malaria. The mortality rate was significantly associated with lower hemoglobin level (P = 0.002); higher total leukocyte count (P = 0.006), blood urea (P < 0.001), serum creatinine (P < 0.001), SGOT (P = 0.001), SGPT (P < 0.007), serum bilirubin (P = 0.003), and parasite density (P = 0.033); lower platelet count (P = 0.043); and those who had more APACHE II score (P = 0.003), SOFA score (P = 0.04), and Multiple Organ Dysfunction Score (P < 0.001) and lower Glasgow Coma Scale (P < 0.001).

CONCLUSIONS

Manifestations of severe malaria is becoming increasingly more prevalent specifically in vivax and mixed malaria cases. Our study proposes that there are certain clinical predictors and prognostic indicators that should be kept in mind for better management of severe malaria.

Dehydration and malaria augment the risk of developing chronic kidney disease in Sri Lanka

Chronic kidney disease (CKD) of unknown etiology (CKDu) is a serious health issue in Sri Lanka. One-to-one age and sex-matched two sample comparative study was carried out in the Medawachchiya divisional secretariat area of the North Central Province (NCP) of Sri Lanka, by randomly selecting 100 CKDu patients and 100 age and sex-matched subjects from non-CKDu affected families from the same area. An interviewer-administered questionnaire was used for the collection of data pertaining to occupation, medical history and lifestyle. Data were analyzed using a conditional linear logistic model. Working for >6 h in the field per day, exposure to sun, drinking water only from well, consumption of <3 L of water per day, and having a history of malaria were found to be having significant (P < 0.05) likelihood toward the development of CKDu. Treatment of water prior to consumption had a significant protective effect against CKDu. Dehydration, history of malaria and drinking untreated well water from are likely contribute to the development of CKD of unknown etiology among the inhabitants of NCP, Sri Lanka.

Dehydration and malaria augment the risk of developing chronic kidney disease in Sri Lanka

Chronic kidney disease (CKD) of unknown etiology (CKDu) is a serious health issue in Sri Lanka. One-to-one age and sex-matched two sample comparative study was carried out in the Medawachchiya divisional secretariat area of the North Central Province (NCP) of Sri Lanka, by randomly selecting 100 CKDu patients and 100 age and sex-matched subjects from non-CKDu affected families from the same area. An interviewer-administered questionnaire was used for the collection of data pertaining to occupation, medical history and lifestyle. Data were analyzed using a conditional linear logistic model. Working for >6 h in the field per day, exposure to sun, drinking water only from well, consumption of <3 L of water per day, and having a history of malaria were found to be having significant (P < 0.05) likelihood toward the development of CKDu. Treatment of water prior to consumption had a significant protective effect against CKDu. Dehydration, history of malaria and drinking untreated well water from are likely contribute to the development of CKD of unknown etiology among the inhabitants of NCP, Sri Lanka.

Plasmodium vivax malaria complicated by splenic infarct

An 11-year-old girl presented with Plasmodium vivax malaria complicated by shock and acute renal failure. The diagnosis of malaria was based on demonstration of trophozoites of P. vivax in the peripheral blood smear and a positive rapid malarial antigen test for P. vivax but negative for P. falciparum. She responded to parenteral artesunate and supportive care. During the course of her infection, she developed pain in her left hypochondrium. Ultrasonography showed multiple hypo-echoic lesions in the spleen and CT scan revealed multiple splenic infarcts. Management was restricted to close clinical monitoring and analgesia. We consider that this is the first report of splenic infarct complicating the course of childhood P. vivax malaria in the English literature. Physicians should suspect and investigate for this rare complication if a patient with malaria complains of left upper quadrant abdominal pain, pleuritic left lower chest pain and/or enlarging tender splenomegaly during the course of malaria infection.

Vivax malaria presenting with myelitis: a rare complication

Neurological complications may occur with the Plasmodium falciparum infection. However, the association of neurological manifestations with vivax malaria remains doubtful. Of late, there are isolated case reports/studies which have implicated P. vivax in the pathogenesis of severe malaria which is characterized by the features of different organ dysfunctions, which were previously thought to be caused by P. falciparum alone. Though several case studies have mentioned the association of the P. vivax infection with cerebral malaria, a causal correlation has yet to be established. Dorsal cord myelitis (which leads to paraplegia) during the febrile illness, is rarely described in association with vivax malaria, though there are reports on the Post Malaria Neurological Syndrome (PMNS) and acute disseminated encephalomyelitis following vivax malaria. We are reporting a case of P. Vivax malaria which presented with myelitis, which responded well to the antimalarial treatment.

Plasmodium vivax: clinical spectrum, risk factors and pathogenesis

Vivax malaria was historically described as 'benign tertian malaria' because individual clinical episodes were less likely to cause severe illness than Plasmodium falciparum. Despite this, Plasmodium vivax was, and remains, responsible for major morbidity and significant mortality in vivax-endemic areas. Single infections causing febrile illness in otherwise healthy individuals rarely progress to severe disease. Nevertheless, in the presence of co-morbidities, P. vivax can cause severe illness and fatal outcomes. Recurrent or chronic infections in endemic areas can cause severe anaemia and malnutrition, particularly in early childhood. Other severe manifestations include acute lung injury, acute kidney injury and uncommonly, coma. Multiorgan failure and shock are described but further studies are needed to investigate the role of bacterial and other co-infections in these syndromes. In pregnancy, P. vivax infection can cause maternal anaemia, miscarriage, low birth weight and congenital malaria. Compared to P. falciparum, P. vivax has a greater capacity to elicit an inflammatory response, resulting in a lower pyrogenic threshold. Conversely, cytoadherence of P. vivax to endothelial cells is less frequent and parasite sequestration is not thought to be a significant cause of severe illness in vivax malaria. With a predilection for young red cells, P. vivax does not result in the high parasite biomass associated with severe disease in P. falciparum, but a four to fivefold greater removal of uninfected red cells from the circulation relative to P. falciparum is associated with a similar risk of severe anaemia. Mechanisms underlying the pathogenesis of severe vivax syndromes remain incompletely understood.

Evidence and implications of mortality associated with acute Plasmodium vivax malaria

Vivax malaria threatens patients despite relatively low-grade parasitemias in peripheral blood. The tenet of death as a rare outcome, derived from antiquated and flawed clinical classifications, disregarded key clinical evidence, including (i) high rates of mortality in neurosyphilis patients treated with vivax malaria; (ii) significant mortality from zones of endemicity; and (iii) the physiological threat inherent in repeated, very severe paroxysms in any patient, healthy or otherwise. The very well-documented course of this infection, with the exception of parasitemia, carries all of the attributes of "perniciousness" historically linked to falciparum malaria, including severe disease and fatal outcomes. A systematic analysis of the parasite biomass in severely ill patients that includes blood, marrow, and spleen may ultimately explain this historic misunderstanding. Regardless of how this parasite is pernicious, recent data demonstrate that the infection comes with a significant burden of morbidity and associated mortality. The extraordinary burden of malaria is not heavily weighted upon any single continent by a single species of parasite-it is a complex problem for the entire endemic world, and both species are of fundamental importance. Humanity must rally substantial resources, intellect, and energy to counter this daunting but profound threat.

Clinical profile of severe malaria: study from a tertiary care center in north India

One hundred and sixty patients having clinical features of severe malaria reported during monsoon season-August-October 2010 at this tertiary care center of north India. Of these 110 (68.75 %) had Plasmodium vivax infection, 30 (18.75 %) were infected with P. falciparum and 20 (12.5 %) had co-infection due to P. vivax and P. falciparum. The diagnosis was made using Rapid Card Test and was confirmed by peripheral smear examination of thick and thin films. Several complications such as acute kidney injury, jaundice, severe anemia, metabolic acidosis, shock, hyperpyrexia, hypoglycemia, generalized tonic-clonic convulsions etc. were found to be more prevalent in patients with P. vivax infection. These symptoms were until recently known to be associated with falciparum malaria.

Malaria in selected non-Amazonian countries of Latin America

Approximately 170 million inhabitants of the American continent live at risk of malaria transmission. Although the continent's contribution to the global malaria burden is small, at least 1-1.2 million malaria cases are reported annually. Sixty percent of the malaria cases occur in Brazil and the other 40% are distributed in 20 other countries of Central and South America. Plasmodium vivax is the predominant species (74.2%) followed by P. falciparum (25.7%) and P. malariae (0.1%), and no less than 10 Anopheles species have been identified as primary or secondary malaria vectors. Rapid deforestation and agricultural practices are directly related to increases in Anopheles species diversity and abundance, as well as in the number of malaria cases. Additionally, climate changes profoundly affect malaria transmission and are responsible for malaria epidemics in some regions of South America. Parasite drug resistance is increasing, but due to bio-geographic barriers there is extraordinary genetic differentiation of parasites with limited dispersion. Although the clinical spectrum ranges from uncomplicated to severe malaria cases, due to the generally low to middle transmission intensity, features such as severe anemia, cerebral malaria and other complications appear to be less frequent than in other endemic regions and asymptomatic infections are a common feature. Although the National Malaria Control Programs (NMCP) of different countries differ in their control activities these are all directed to reduce morbidity and mortality by using strategies like health promotion, vector control and impregnate bed nets among others. Recently, international initiatives such as the Malaria Control Program in Andean-country Border Regions (PAMAFRO) (implemented by the Andean Organism for Health (ORAS) and sponsored by The Global Fund to Fight AIDS, Tuberculosis and Malaria (GFATM)) and The Amazon Network for the Surveillance of Antimalarial Drug Resistance (RAVREDA) (sponsored by the Pan American Health Organization/World Health Organization (PAHO/WHO) and several other partners), have made great investments for malaria control in the region. We describe here the current status of malaria in a non-Amazonian region comprising several countries of South and Central America participating in the Centro Latino Americano de Investigación en Malaria (CLAIM), an International Center of Excellence for Malaria Research (ICEMR) sponsored by the National Institutes of Health (NIH) National Institute of Allergy and Infectious Diseases (NIAID).

Oxygen therapy for cerebral malaria

Malaria is an important global health issue, killing nearly one million people worldwide each year. There is a disproportionate disease burden, since 89% of cases are of African origin, and 85% of deaths worldwide occur in children under 5 years of age of age.(1) Cerebral malaria (CM) is the most serious complication of infection. Despite prompt anti-malarial treatment, fatalities remain high - mortality rates while undergoing treatment with Artemisinin or quinine-based therapy reach 15% and 22% respectively.(2) There is, therefore, a need to develop an adjunct therapy to preserve neurological function during the treatment period. Recent experimental research has indicated hyperbaric oxygenation (HBO) to be a rational and effective adjunct therapy.(3) This article examines the current understanding of CM, and the possible benefits provided by HBO therapy.

Coma associated with microscopy-diagnosed Plasmodium vivax: a prospective study in Papua, Indonesia

BACKGROUND

Coma complicates Plasmodium falciparum infection but is uncommonly associated with P. vivax. Most series of vivax coma have been retrospective and have not utilized molecular methods to exclude mixed infections with P. falciparum.

METHODS

We prospectively enrolled patients hospitalized in Timika, Indonesia, with a Glasgow Coma Score (GCS) ≤10 and P. vivax monoinfection on initial microscopy over a four year period. Hematological, biochemical, serological, radiological and cerebrospinal fluid (CSF) examinations were performed to identify other causes of coma. Repeat microscopy, antigen detection and polymerase chain reaction (PCR) were performed to exclude infections with other Plasmodium species.

RESULTS

Of 24 patients fulfilling enrolment criteria, 5 had clear evidence for other non-malarial etiologies. PCR demonstrated 10 mixed infections and 3 P. falciparum monoinfections. 6 (25%) patients had vivax monoinfection and no apparent alternative cause, with a median GCS of 9 (range 8-10) and a median coma duration of 42 (range 36-48) hours. CSF leukocyte counts were <10/ul (n=3); 2 of the 3 patients without CSF examination recovered with antimalarial therapy alone. One patient had a tremor on discharge consistent with a post-malarial neurological syndrome. No patient had other organ dysfunction. The only death was associated with pure P. falciparum infection by PCR. Vivax monoinfection-associated risk of coma was estimated at 1 in 29,486 clinical vivax infections with no deaths. In comparison, the risk of falciparum-associated coma was estimated at 1 in 1,276 clinical infections with an 18.5% mortality rate.

CONCLUSIONS

P. vivax-associated coma is rare, occurring 23 times less frequently than that seen with falciparum malaria, and is associated with a high proportion of non-malarial causes and mixed infections using PCR. The pathogenesis of coma associated with vivax malaria, particularly the role of comorbidities, is uncertain and requires further investigation.

Clinical features of children hospitalized with malaria--a study from Bikaner, northwest India

Severe Plasmodium vivax malaria in adults has been reported from Bikaner (northwestern India) but the reports on children are scanty. This prospective study was done on 303 admitted children of malaria. The diagnosis was done by peripheral blood smear and rapid diagnostic test. Further confirmation of severe P. vivax monoinfection was done by polymerase chain reaction (PCR). The proportion of P. falciparum, P. vivax, and mixed (P. falciparum and P. vivax) infection was 61.01%, 33.99%, and 4.95%, respectively. Severe disease was present in 49.5% (150/303) children with malaria, with the risk greatest among P. vivax monoinfection (63.1% [65/103]) compared with P. falciparum, either alone (42.7% [79/185]; odds ratio [OR] = 2.3 [95% confidence interval (CI) = 1.40-3.76], P = 0.001) or mixed infections (40% [6/15]; OR = 2.57 [95% CI = 0.88-7.48]). In children < 5 years of age, the proportion of severe malaria attributable to P. vivax rose to 67.4% (31/46) compared with 30.4% (14/46) of P. falciparum (OR = 4.7 [95% CI = 2.6-8.6], P < 0.0001) and 2.2% (1/46) of mixed infection (OR = 92 [95% CI = 24.6-339.9], P < 0.0001). The proportion of patients having severe manifestations, which included severe anemia, thrombocytopenia, cerebral malaria, acute respiratory distress syndrome, hepatic dysfunction, renal dysfunction, abnormal bleeding was significantly high in association with P. vivax monoinfection in 0-5 year age group, while the same was significantly high in association with P. falciparum monoinfection in 5-10 year age group. Similarly P. vivax monoinfection had greatest propensity to cause multiorgan dysfunction in 0-5 year age group (34.1% [17/41], P < 0.0001) in comparison to P. falciparum monoinfection, which had similar propensity in 5-10 year age group (36.8% [35/95], P = 0.039). Plasmodium vivax monoinfection was almost equally serious to cause significant mortality in comparison to P. falciparum (case fatality rate of severe P. vivax was 3.9% versus 3.2% of severe P. falciparum malaria; P = 1.0). This study reaffirms the evidence of severe P. vivax malaria in children in Bikaner.

Cerebral malaria caused by Plasmodium vivax in adult subjects

Cerebral malaria is a diffuse encephalopathy associated with seizures and status epilepticus which can occur in up to one-third of patients with severe malaria, particularly that caused by Plasmodium falciparum.

In this article, we report three cases of Plasmodium vivax malaria (all adult male patients) complicated by seizures and symptoms of diffuse meningoencephalitis. Two patients had predominantly meningeal signs, while in the third patient the features were purely of encephalitis All cases were treated with artesunate. Usually, cerebral malaria is caused by P. falciparum, and rarely, cerebral malaria is a presenting complication or occurs during the course of P. vivax infection.

Severe Plasmodium vivax malaria exhibits marked inflammatory imbalance

BACKGROUND

Despite clinical descriptions of severe vivax malaria cases having been reported, data regarding immunological and inflammatory patterns are scarce. In this report, the inflammatory and immunological status of both mild and severe vivax malaria cases are compared in order to explore immunopathological events in this disease.

METHODS AND RESULTS

Active and passive malaria case detections were performed during 2007 in Buritis, Rondônia, in the Brazilian Amazon. A total of 219 participants enrolled the study. Study individuals were classified according to the presence of Plasmodium vivax infection within four groups: non-infected (n = 90), asymptomatic (n = 60), mild (n = 50) and severe vivax infection (n = 19). A diagnosis of malaria was made by microscopy and molecular assays. Since at present no clear criteria define severe vivax malaria, this study adapted the consensual criteria from falciparum malaria. Patients with severe P. vivax infection were younger, had lived for shorter time in the endemic area, and recalled having experienced less previous malaria episodes than individuals with no malaria infection and with mild or asymptomatic infection. Strong linear trends were identified regarding increasing plasma levels of C reactive protein (CRP), serum creatinine, bilirubins and the graduation of disease severity. Plasma levels of tumour necrosis factor (TNF), interferon-gamma(IFN-gamma) and also IFN-gamma/interleukin-10 ratios were increased and exhibited a linear trend with gradual augmentation of disease severity. Both laboratory parameters of organ dysfunction and inflammatory cytokines were reduced during anti-parasite therapy in those patients with severe disease.

CONCLUSION

Different clinical presentations of vivax malaria infection present strong association with activation of pro-inflammatory responses and cytokine imbalance. These findings are of utmost importance to improve current knowledge about physiopathological concepts of this serious widespread disease.

[Plasmodium vivax infection: not so benign]

Morbidity and mortality during malaria are mostly due to Plasmodium falciparum infection. However, it becomes clear that Plasmodium vivax is responsible for a dramatic toll in many endemic areas except Africa. Cerebral malaria, severe respiratory distress and severe anaemia were recently reported from different settings, with severe disease peaking at an earlier age than those of Plasmodium falciparum. Since infected red blood cells sequestration was not reported with Plasmodium vivax infection, mechanisms at the origin of these complications are still a mater of debate. The major issue addressed in that paper is to alert clinicians on the -potential severity of this "benign tertian fever".

Advances in the management of cerebral malaria in adults

PURPOSE OF REVIEW

Cerebral malaria continues to be a substantial cause of death and disability worldwide. Although many studies deal with cerebral malaria in children, only very few pertain to adults. Presence of multiorgan failure makes the prognosis poor. Various mechanisms in the pathogenesis of cerebral malaria and the role of adjuvant therapy will be discussed.

RECENT FINDINGS

Artemisinin-based therapies have improved antiparasitic treatment, but in-hospital mortality still remains high, as do neurological sequelae. Several recent studies have given new insights in the pathophysiology of cerebral malaria particularly the role of immune mechanisms in disease progression. Recent findings have identified several potential candidates for adjuvant neuroprotective treatment. Recombinant human erythropoietin has shown beneficial effect in experimental cerebral malaria and will soon enter into large clinical trials.

SUMMARY

Advances have been made in terms of antiparasitic treatment, but the identification of a well tolerated and effective adjuvant treatment to increase survival and reduce brain damage is still pending. The search for new approaches is a major challenge, not least of which is that mechanisms of malaria pathogenesis remain incompletely understood. The paper reviews newer information on pathogenesis and strategies in the management of cerebral malaria in adults.

Resistance to therapies for infection by Plasmodium vivax

The gravity of the threat posed by vivax malaria to public health has been poorly appreciated. The widely held misperception of Plasmodium vivax as being relatively infrequent, benign, and easily treated explains its nearly complete neglect across the range of biological and clinical research. Recent evidence suggests a far higher and more-severe disease burden imposed by increasingly drug-resistant parasites. The two frontline therapies against vivax malaria, chloroquine and primaquine, may be failing. Despite 60 years of nearly continuous use of these drugs, their respective mechanisms of activity, resistance, and toxicity remain unknown. Although standardized means of assessing therapeutic efficacy against blood and liver stages have not been developed, this review examines the provisional in vivo, ex vivo, and animal model systems for doing so. The rationale, design, and interpretation of clinical trials of therapies for vivax malaria are discussed in the context of the nuance and ambiguity imposed by the hypnozoite. Fielding new drug therapies against real-world vivax malaria may require a reworking of the strategic framework of drug development, namely, the conception, testing, and evaluation of sets of drugs designed for the cure of both blood and liver asexual stages as well as the sexual blood stages within a single therapeutic regimen.

Plasmodium vivax: sequence polymorphism and effect of natural selection at apical membrane antigen 1 (PvAMA1) among Indian population

Present study describes the characterization of apical membrane antigen 1 (PvAMA1) polymorphisms among Indian Plasmodium vivax isolates. The partial PvAMA1 gene (covering domain I and domain II regions) sequenced from sixty-one (n=61) isolates in this study resulted into 49 haplotypes. Comparison with the previously available PvAMA1 sequences in the GenBank database revealed that 45 of these were new haplotypes that have never been reported till date. For further analyses, we also included 11 previously reported PvAMA1 sequences from India available in the database. Thus genetic diversity and effect of natural selection were analyzed both at domain I and domain II of this promising malaria vaccine candidate among 72 Indian P. vivax isolates. Non-synonymous mutations were found at 25 codons (16 at domain I and 9 at domain II) where 17 codons were dimorphic while rest of them (8 codons) were trimorphic. Thus codon polymorphisms were observed to be more at domain I as compared to domain II. Although the difference between the rate of non-synonymous (dN) and synonymous (dS) mutations was positive (dN-dS, 0.002+/-0.004SE) at domain II, it was not significantly different from each other (P=0.272), indicating tendency of stronger diversifying selection at this domain. The dN-dS difference for domain I (-0.006+/-0.009SE, P=0.268) and for entire 900 bp region (-0.002+/-0.005E, P=0.320) being negative and statistically insignificant suggests the role of both positive as well as purifying selection. Three-dimensional distributions of all polymorphic residues were mapped on a modeled PvAMA1 structure. Results suggested that almost all of the observed polymorphisms were located at one surface of the antigen. In conclusion, PvAMA1 antigen displays high diversity among Indian isolates with more diversifying selection at domain II. The result has significant value in malaria vaccine development using this antigen.

Neglect of Plasmodium vivax malaria

Plasmodium vivax infects 130-435 million of the 2.6 billion people living at risk of infection. Recent studies suggest that vivax malaria can become lethal in a similar way to severe falciparum malaria. First-line therapies remain unchanged after 50 years. Despite evidence of failing chloroquine efficacy, little work has assessed the problem or explored alternative therapies. Primaquine treatment, the only therapeutic option against relapse, might also be failing. No licensed primary chemoprophylactic agent protects travelers from relapse. Misdiagnosis of species now affects clinical decisions resulting in inadequate therapy for P. falciparum and P. vivax. All of these factors demonstrate the lack of research on P. vivax.