Malaria mortality in Venezuela: focus on deaths due to Plasmodium vivax in children

Plasmodium vivax in Children: Hidden Burden and Conspicuous Challenges, a Narrative Review

There has been progress towards decreasing malaria prevalence globally; however, Plasmodium vivax has been less responsive to elimination efforts compared with Plasmodium falciparum. P. vivax malaria remains a serious public health concern in regions where it is the dominant species (South and South-East Asia, the Eastern Mediterranean region, and South America) and is increasingly recognized for its contribution to overall morbidity and mortality worldwide. The incidence of P. vivax decreases with increasing age owing to rapidly acquired clinical immunity and there is a disproportionate burden of P. vivax in infants and children, who remain highly vulnerable to severe disease, recurrence, and anemia with associated developmental impacts. Diagnosis is sometimes difficult owing to the sensitivity of diagnostic tests to detect low levels of parasitemia. Additionally, the propensity of P. vivax to relapse following reactivation of dormant hypnozoites in the liver contributes to disease recurrence in infants and children, and potentiates morbidity and transmission. The 8-aminoquinolines, primaquine and tafenoquine, provide radical cure (relapse prevention). However, the risk of hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency necessitates testing prior to administration of 8-aminoquinolines, which has limited their uptake. Additional challenges include lack of availability of pediatric dose formulations and problems with adherence to primaquine owing to the length of treatment recommended. A paucity of data and studies specific to pediatric P. vivax malaria impacts the ability to deliver targeted interventions. It is imperative that P. vivax in infants and children be the focus of future research, control initiatives, and anti-malarial drug development.

Efficacy Study of Chloroquine to Plasmodium vivax Malaria in Darimu and Bure Districts, Southwest Ethiopia

Background

Chloroquine (CQ) is the first line treatment for vivax malaria in Ethiopia. However, the therapeutic efficacy of the drug is now declining. Several reports from different areas of the country showed CQ-vivax treatment failure increasing. This study therefore aimed to provide additional data on the therapeutic efficacy of CQ against Plasmodium vivax malaria from two districts of Southwestern Ethiopia.

Methods

An observational prospective study among P. vivax malaria infected individuals was conducted in two districts of Southwest Ethiopia for a period of 28 follow-up days. Study participants were treated with 25 mg/kg of standard CQ for 3 consecutive days according to the procedure. Microscopic blood film examinations and other clinical assessments were measured within the follow-up period on a weekly basis.

Results

A total of 115 patients were enrolled in the study. Sixty-five were from Darimu and 50 were from Bure districts. The majority (67%) of study participants were male and 86.1% (99/115) were below 35 years old. The study revealed that CQ treatment was able to clear vivax malaria parasites and febrile within a week. During the follow-up study period, recurrence of vivax parasitemia was not recorded. However, there was a marked heterogeneity with respect to fever clearance time, parasitemia load, and carriage of parasite gametocyte within 72 hours of post-treatment between the two study areas.

Conclusion

The present study revealed that CQ has good clinical and parasitological response to vivax malaria in the study areas. Thus, it can be continued as the first line P. vivax malaria treatment. However, further monitoring and evaluation of the drug should be considered.

Genomic Analysis Reveals a Common Breakpoint in Amplifications of the Plasmodium vivax Multidrug Resistance 1 Locus in Thailand

In regions of coendemicity for Plasmodium falciparum and Plasmodium vivax where mefloquine is used to treat P. falciparum infection, drug pressure mediated by increased copy numbers of the multidrug resistance 1 gene (pvmdr1) may select for mefloquine-resistant P. vivax Surveillance is not undertaken routinely owing in part to methodological challenges in detection of gene amplification. Using genomic data on 88 P. vivax samples from western Thailand, we identified pvmdr1 amplification in 17 isolates, all exhibiting tandem copies of a 37.6-kilobase pair region with identical breakpoints. A novel breakpoint-specific polymerase chain reaction assay was designed to detect the amplification. The assay demonstrated high sensitivity, identifying amplifications in 13 additional, polyclonal infections. Application to 132 further samples identified the common breakpoint in all years tested (2003-2015), with a decline in prevalence after 2012 corresponding to local discontinuation of mefloquine regimens. Assessment of the structure of pvmdr1 amplification in other geographic regions will yield information about the population-specificity of the breakpoints and underlying amplification mechanisms.

Plasmodium vivax infection: a major determinant of severe anaemia in infancy

BACKGROUND

Most malarious countries outside of Africa are co-endemic for Plasmodium falciparum and Plasmodium vivax. The comparative burden of anaemia in the community caused by these two species is incompletely characterized.

METHODS

A three-stage, cross-sectional, community survey was used to determine the proportion of moderate or severe anaemia (haemoglobin <7 g/dL) attributable to patent P. vivax, P. falciparum and mixed parasitaemia in Papua, Indonesia. Adjusted population-attributable fractions were calculated from multivariable logistic regression models. Eight hundred and twenty-five households were surveyed with a total of 5255 occupants, 3890 (74 %) of whom were present and provided a blood sample. Plasmodium falciparum parasitaemia was present in 8.1 % (n = 315) of participants, P. vivax in 6.4 % (n = 250) and mixed infections in 1.9 % (n = 72). Overall, P. falciparum was associated with a mean reduction in haemoglobin of 1.16 g/dL compared to those without patent parasitaemia [95 % confidence interval (95 % CI) 0.91, 1.41 g/dL]. The corresponding values for P. vivax and mixed infections were 0.66 g/dL (95 % CI 0.35, 0.96) and 1.25 g/dL (0.71, 1.80), respectively. Overall, 16.7 % (95 % CI 8.52, 24.2 %) of haemoglobin concentrations <7 g/dL in the community were estimated to be attributable to patent parasitaemia. The fractions for infants and 1-5 years old were 34.4 % (95 % CI -3.30, 58.3 %) and 23.2 % (95 % CI 3.34, 39.0 %), respectively. Plasmodium vivax was associated with a greater than threefold higher attributable fraction of anaemia in infants compared with P. falciparum [27.6 % (95 % CI -3.20, 49.2 %) versus 7.94 % (-5.87, 20.0 %)].

CONCLUSION

Despite comparatively low-level endemicity, malaria is associated with a significant proportion of all cases of community anaemia in southern Papua. Contrary to its benign reputation, P. vivax is an important and preventable risk factor for anaemia during infancy-a probable consequence of relapsing disease prior to the development of immunity.

Clinical and epidemiological aspects of complicated malaria in Colombia, 2007-2013

BACKGROUND

During the last decade, Colombia presented a significant decrease in malaria clinical cases and associated mortality. However, there is a lack of reliable information about the prevalence and characteristics of complicated malaria cases as well as its association with different Plasmodium species. A description of the epidemiological and clinical aspects of complicated malaria in Colombia is presented here.

METHODS

A descriptive study was conducted using data collected between 2007 and 2013 by the Public Health Surveillance System (SIVIGILA). Demographic and clinical features were described. Frequency of complicated malaria cases, annual parasite index (API) and annual percent change (APC) for trend modelling by gender and age were also calculated.

RESULTS

A total of 547,542 malaria cases were recorded by SIVIGILA during the study period, of which 2553 (0.47 %) corresponded to complicated cases with similar distribution by Plasmodium vivax and Plasmodium falciparum species. Mixed infections were found in 153 cases (6.0 %). Trend modelling of the API for complicated malaria for all parasite species showed a non-significant increase throughout the years (APC 14.4 %; 95 % CI -4.3 to 36.6 %). Complicated malaria individuals were mostly males (62.2 %) and young adults (median age of 23 years). Notably, 72.4 % of the patients attended for malaria diagnosis >72 h after symptoms onset and 17 % reported malaria episodes in the last 30 days. All patients received anti-malarial treatment, but only 40 % received the first-line as recommended by the Colombian guidelines. Overall, hepatic and renal complications were the most common severe manifestations (63.6 %). Whereas hepatic and pulmonary complications were more common in P. vivax infections, renal and cerebral complications were significantly more frequent in patients with P. falciparum. In contrast with mono-infected patients, severe anaemia and shock were more frequent in patients with mixed infection.

CONCLUSION

In contrast with the malaria-decreasing trend over the last years, the complicated malaria trend showed a non-significant annual increase. Therefore, in addition to existing national policies on early diagnosis and prompt anti-malarial treatment, more efforts have to be committed addressing the delayed diagnosis and inadequate treatment found in this study. Improving malaria notification forms, medical assistance skills, and capacity should be prioritized.

Epidemiology of Malaria in Latin America and the Caribbean from 1990 to 2009: Systematic Review and Meta-Analysis

OBJECTIVE

The objective of this study was to evaluate the burden of malaria in Latin America and the Caribbean countries through a systematic review and meta-analysis of published literature, gray literature, and information from countries' public health authorities for the period 1990 to 2009.

METHODS

The random-effects meta-analysis of the prospective studies, carried out in very highly endemic areas, showed an annual incidence rate of 409.0 malaria episodes/1000 person-years (95% confidence interval [CI] 263.1-554.9), considering all ages, which was 40-fold the one estimated from areas with passive surveillance only.

RESULTS

Overall, the most prevalent species was Plasmodium vivax (77.5%; 95% CI 75.6-79.4) followed by Plasmodium falciparum (20.8%; 95% CI 19.0-22.6) and Plasmodium malariae (0.08%; 95% CI 0.07-0.010). Data from regional ministries of health yielded an estimated pooled crude annual mortality rate of 6 deaths/100,000 people, mainly associated with P. falciparum.

CONCLUSION

This study represents the first systematic review of the burden of malaria in Latin America and the Caribbean, with data from 21 countries.

Mortality attributable to Plasmodium vivax malaria: a clinical audit from Papua, Indonesia

BACKGROUND

Plasmodium vivax causes almost half of all malaria cases in Asia and is recognised as a significant cause of morbidity. In recent years it has been associated with severe and fatal disease. The extent to which P. vivax contributes to death is not known.

METHODS

To define the epidemiology of mortality attributable to vivax malaria in southern Papua, Indonesia, a retrospective clinical records-based audit was conducted of all deaths in patients with vivax malaria at a tertiary referral hospital.

RESULTS

Between January 2004 and September 2009, hospital surveillance identified 3,495 inpatients with P. vivax monoinfection and 65 (1.9%) patients who subsequently died. Charts for 54 of these 65 patients could be reviewed, 40 (74%) of whom had pure P. vivax infections on cross-checking. Using pre-defined conservative criteria, vivax malaria was the primary cause of death in 6 cases, a major contributor in 17 cases and a minor contributor in a further 13 cases. Extreme anaemia was the most common primary cause of death. Malnutrition, sepsis with respiratory and gastrointestinal manifestations, and chronic diseases were the commonest attributed causes of death for patients in the latter two categories. There were an estimated 293,763 cases of pure P. vivax infection in the community during the study period giving an overall minimum case fatality of 0.12 per 1,000 infections. The corresponding case fatality in hospitalised patients was 10.3 per 1,000 infections.

CONCLUSIONS

Although uncommonly directly fatal, vivax malaria is an important indirect cause of death in southern Papua in patients with malnutrition, sepsis syndrome and chronic diseases, including HIV infection.

Global extent of chloroquine-resistant Plasmodium vivax: a systematic review and meta-analysis

BACKGROUND

Chloroquine is the first-line treatment for Plasmodium vivax malaria in most endemic countries, but resistance is increasing. Monitoring of antimalarial efficacy is essential, but in P. vivax infections the assessment of treatment efficacy is confounded by relapse from the dormant liver stages. We systematically reviewed P. vivax malaria treatment efficacy studies to establish the global extent of chloroquine resistance.

METHODS

We searched Medline, Web of Science, Embase, and the Cochrane Database of Systematic Reviews to identify studies published in English between Jan 1, 1960, and April 30, 2014, which investigated antimalarial treatment efficacy in P. vivax malaria. We excluded studies that did not include supervised schizonticidal treatment without primaquine. We determined rates of chloroquine resistance according to P. vivax malaria recurrence rates by day 28 whole-blood chloroquine concentrations at the time of recurrence and study enrolment criteria.

FINDINGS

We identified 129 eligible clinical trials involving 21,694 patients at 179 study sites and 26 case reports describing 54 patients. Chloroquine resistance was present in 58 (53%) of 113 assessable study sites, spread across most countries that are endemic for P. vivax. Clearance of parasitaemia assessed by microscopy in 95% of patients by day 2, or all patients by day 3, was 100% predictive of chloroquine sensitivity.

INTERPRETATION

Heterogeneity of study design and analysis has confounded global surveillance of chloroquine-resistant P. vivax, which is now present across most countries endemic for P. vivax. Improved methods for monitoring of drug resistance are needed to inform antimalarial policy in these regions.

FUNDING

Wellcome Trust (UK).

Congenital malaria in a neonate: case report with a comprehensive review on differential diagnosis, treatment and prevention in Indian perspective

Although malaria in pregnancy, lactation and congenital malaria can be a disease burden in the endemic zones of Africa and Indian sub-continent, it is still epidemiologically less investigated in India. As it may lead to considerable maternal and perinatal morbidity and mortality, awareness and timely intervention is necessary for desirable outcome and prevention of the condition. Very few reports of congenital malaria are available in the literature from an endemic country like India. Herein we describe a case of congenital malaria from north India in a 21-day neonate. Clinical presentation of this condition in the neonate may offer a considerable diagnostic challenge, and differentiation from vector borne malaria in infants may be important from the management point of view. Hence a review of the differential diagnosis, management and prevention of congenital malaria has been attempted in the Indian perspective.

Spatial patterns of malaria reported deaths in Yunnan Province, China

Malaria has been a heavy social and health burden in the remote and poor areas in southern China. Analyses of malaria epidemic patterns can uncover important features of malaria transmission. This study identified spatial clusters, seasonal patterns, and geographic variations of malaria deaths at a county level in Yunnan, China, during 1991-2010. A discrete Poisson model was used to identify purely spatial clusters of malaria deaths. Logistic regression analysis was performed to detect changes in geographic patterns. The results show that malaria mortality had declined in Yunnan over the study period and the most likely spatial clusters (relative risk [RR] = 23.03-32.06, P < 0.001) of malaria deaths were identified in western Yunnan along the China-Myanmar border. The highest risk of malaria deaths occurred in autumn (RR = 58.91, P < 0.001) and summer (RR = 31.91, P < 0.001). The results suggested that the geographic distribution of malaria deaths was significantly changed with longitude, which indicated there was decreased mortality of malaria in eastern areas over the last two decades, although there was no significant change in latitude during the same period. Public health interventions should target populations in western Yunnan along border areas, especially focusing on floating populations crossing international borders.

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.

Plasmodium vivax malaria admissions and risk of mortality in a tertiary-care children's hospital in North India

BACKGROUND

In 2010, there was an increase in the severity of malaria admissions to Kalawati Saran Children's Hospital, New Delhi and this report describes the morbidity and mortality profile.

METHOD

A retrospective chart review of patients admitted with parasitologically confirmed malaria between January and December 2010.

RESULTS

There were 156 cases: P. vivax 105 (67.3%), P. falciparum 39 (25%) and mixed infections 12 (7.7%). Thrombocytopenia (platelet count <150×10(9)/L) was present in 90 (85.7%) patients with P. vivax mono-infection. There were 91 (58.3%) patients with severe malaria: P. vivax mono-infection 46 (50.5%), P. falciparum mono-infection 35 (38.5%) and mixed 10 (11%). Severe anaemia and severe thrombocytopenia (platelet count <20×10(9)/L) were detected significantly more often in P. falciparum and P. vivax mono-infection, respectively. Complications including cerebral malaria, acute renal failure, shock, acute respiratory distress syndrome (ARDS) and multiple-organ dysfunction syndrome (MODS) were similar in both groups. The mortality rate of around 20% was similar in severe P. vivax and P. falciparum mono-infection. Risk of mortality in vivax malaria was highest in patients with ARDS followed by MODS and shock.

CONCLUSION

Increased morbidity owing to P. vivax malaria was observed and risk of mortality was highest in patients with ARDS and MODS.

Clinical aspects of uncomplicated and severe malaria

The first symptoms of malaria, common to all the different malaria species, are nonspecific and mimic a flu-like syndrome. Although fever represents the cardinal feature, clinical findings in malaria are extremely diverse and may range in severity from mild headache to serious complications leading to death, particularly in falciparum malaria. As the progression to these complications can be rapid, any malaria patient must be assessed and treated rapidly, and frequent observations are needed to look for early signs of systemic complications.

In fact, severe malaria is a life threatening but treatable disease. The protean and nonspecific clinical findings occurring in malaria (fever, malaise, headache, myalgias, jaundice and sometimes gastrointestinal symptoms of nausea, vomiting and diarrhoea) may lead physicians who see malaria infrequently to a wrong diagnosis, such as influenza (particularly during the seasonal epidemic flu), dengue, gastroenteritis, typhoid fever, viral hepatitis, encephalitis. Physicians should be aware that malaria is not a clinical diagnosis but must be diagnosed, or excluded, by performing microscopic examination of blood films. Prompt diagnosis and appropriate treatment are then crucial to prevent morbidity and fatal outcomes. Although Plasmodium falciparum malaria is the major cause of severe malaria and death, increasing evidence has recently emerged that Plasmodium vivax and Plasmodium knowlesi can also be severe and even fatal.

The anaemia of Plasmodium vivax malaria

Plasmodium vivax threatens nearly half the world's population and is a significant impediment to achievement of the millennium development goals. It is an important, but incompletely understood, cause of anaemia. This review synthesizes current evidence on the epidemiology, pathogenesis, treatment and consequences of vivax-associated anaemia. Young children are at high risk of clinically significant and potentially severe vivax-associated anaemia, particularly in countries where transmission is intense and relapses are frequent. Despite reaching lower densities than Plasmodium falciparum, Plasmodium vivax causes similar absolute reduction in red blood cell mass because it results in proportionately greater removal of uninfected red blood cells. Severe vivax anaemia is associated with substantial indirect mortality and morbidity through impaired resilience to co-morbidities, obstetric complications and requirement for blood transfusion. Anaemia can be averted by early and effective anti-malarial treatment.

Review: Malaria chemoprophylaxis for travelers to Latin America

Because of recent declining malaria transmission in Latin America, some authorities have recommended against chemoprophylaxis for most travelers to this region. However, the predominant parasite species in Latin America, Plasmodium vivax, can form hypnozoites sequestered in the liver, causing malaria relapses. Additionally, new evidence shows the potential severity of vivax infections, warranting continued consideration of prophylaxis for travel to Latin America. Individualized travel risk assessments are recommended and should consider travel locations, type, length, and season, as well as probability of itinerary changes. Travel recommendations might include no precautions, mosquito avoidance only, or mosquito avoidance and chemoprophylaxis. There are a range of good options for chemoprophylaxis in Latin America, including atovaquone-proguanil, doxycycline, mefloquine, and--in selected areas--chloroquine. Primaquine should be strongly considered for nonpregnant, G6PD-nondeficient patients traveling to vivax-endemic areas of Latin America, and it has the added benefit of being the only drug to protect against malaria relapses.

Plasmodium vivax treatments: what are we looking for?

PURPOSE OF REVIEW

For over 50 years, the treatment of Plasmodium vivax has relied on a combination of chloroquine and primaquine, but this strategy is under threat. Chloroquine efficacy is now compromised across much of the vivax endemic world and there are significant operational difficulties in deploying primaquine. We review the recent advances in P. vivax chemotherapy that may influence the future management of this neglected pathogen.

RECENT FINDINGS

New-generation artemisinin combination therapies (ACTs) have shown potent efficacy against the erythrocytic stages of both drug-resistant P. vivax and Plasmodium falciparum. Antimalarial regimens containing slowly eliminated drugs provide a measure of protection against the first, and possibly second, relapse of tropical strains of P. vivax, but reliable radical cure is needed to prevent future relapses. Primaquine is currently the only licensed hypnozoitocidal treatment, but requires long treatment courses and its effectiveness in different endemic settings remains largely unknown.

SUMMARY

In regions coendemic for P. vivax and P. falciparum, a unified treatment policy for malaria of any parasitological cause is likely to confer the greatest individual and public health benefit. Optimizing the safety and effectiveness of primaquine through the development of rapid diagnostic tests for glucose-6-phosphate dehydrogenase deficiency and improving drug adherence will be crucial endeavors in the fight against vivax malaria.

In vitro anti-malarial drug susceptibility of temperate Plasmodium vivax from central China

In the face of recent increase of Plasmodium vivax malaria in central China, we conducted a study to evaluate in vitro susceptibility of temperate-zone P. vivax parasites to antimalarial drugs. During 2005-2006, in vitro drug susceptibility was measured for 42 clinical P. vivax isolates by using a schizont maturation inhibition technique. Geometric means of 50% inhibitory concentrations (IC(50)s) and 95% confidence intervals (CIs) were 10.87 (4.50-26.26) ng/mL for chloroquine, 4.21 (1.88-9.42-8) ng/mL for mefloquine, 11.82 (6.20-22.56) ng/mL for quinine, 0.13 (0.09-0.20) ng/mL for artesunate, 18.32 (8.08-41.50) ng/mL for pyrimethamine, and 17.73 (10.29-30.57) ng/mL for piperaquine. The IC(50) for chloroquine was lower than those obtained from isolates from Thailand and South Korea, suggesting that chloroquine remained effective against P. vivax malaria in central China. The results further indicated that temperate-zone P. vivax isolates from China were more susceptible to chloroquine, quinine, and mefloquine than isolates from Thailand.

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.

Transfusion-related Plasmodium ovale malaria complicated by acute respiratory distress syndrome (ARDS) in a non-endemic country

46year old female presented with a one week history of high grade fever, chills, cough, and severe nausea. The patient had been admitted a month earlier with severe lower gastrointestinal bleeding from hemorrhoids necessitating transfusion of 7 units of packed red blood cells. Initial work-up was unremarkable. Because of persistent symptoms, the patient was admitted 2 days later. Malaria smear was positive. Due to the severity of her symptoms, she was managed as falciparum malaria and was started on intravenous quinine and oral doxycycline. On the second day of treatment the patient developed respiratory failure, requiring intubation and ventilatory support with new bilateral pulmonary infiltrates. Antimalarial treatment was continued for a total of 7 days followed by primaquine for 14 days once the blood smear results revealed Plasmodium ovale infection. The patient remained intubated in the intensive care unit (ICU) for 16 days, and was later extubated successfully with a clear chest x-ray after a total of one month hospitalization. To our knowledge, this is the first case of acute respiratory distress syndrome (ARDS) secondary to blood transfusion related P. ovale malaria infection in a non-endemic country.

Artemisinin combination therapy for vivax malaria

Early parasitological diagnosis and treatment with artemisinin-based combination therapies (ACTs) are key components of worldwide malaria elimination programmes. In general, use of ACTs has been limited to patients with falciparum malaria whereas blood-stage infections with Plasmodium vivax are mostly still treated with chloroquine. We review the evidence for the relative benefits and disadvantages of the existing separate treatment approach versus a unified ACT-based strategy for treating Plasmodium falciparum and P vivax infections in regions where both species are endemic (co-endemic). The separate treatment scenario is justifiable if P vivax remains sensitive to chloroquine and diagnostic tests reliably distinguish P vivax from P falciparum. However, with the high number of misdiagnoses in routine practice and the rise and spread of chloroquine-resistant P vivax, there might be a compelling rationale for a unified ACT-based strategy for vivax and falciparum malaria in all co-endemic regions. Analyses of the cost-effectiveness of ACTs for both Plasmodium species are needed to assess the role of these drugs in the control and elimination of vivax malaria.

Limited global diversity of the Plasmodium vivax merozoite surface protein 4 gene

Merozoite surface proteins (MSPs) of the malaria parasites are major candidates for vaccine development targeting asexual blood stages. However, the diverse antigenic repertoire of these antigens that induce strain-specific protective immunity in human is a major challenge for vaccine design and often determines the efficacy of a vaccine. Here we further assessed the genetic diversity of Plasmodium vivax MSP4 (PvMSP4) protein using 195 parasite samples collected mostly from Thailand, Indonesia and Brazil. Overall, PvMSP4 is highly conserved with only eight amino acid substitutions. The majority of the haplotype diversity was restricted to the two short tetrapeptide repeat arrays in exon 1 and 2, respectively. Selection and neutrality tests indicated that exon 1 and the entire coding region of PvMSP4 were under purifying selection. Despite the limited nucleotide polymorphism of PvMSP4, significant genetic differentiation among the three major parasite populations was detected. Moreover, microgeographical heterogeneity was also evident in the parasite populations from different endemic areas of Thailand.

Polymorphism in the Plasmodium vivax msp 3: gene in field samples from Tierralta, Colombia

We evaluated the Plasmodium vivax polymorphism by studying the Pvmsp-3alpha gene's polymorphic region by PCR-RFLP in 55 samples from patients living in Tierralta, Colombia. Three different sizes of the Pvmsp-3 alpha gene were found, type A (1,900 bp), type B (1,500 bp) and type C (1,100 bp); most of the samples were type A (96.4 %). The Pvmsp-3alpha gene exhibited high polymorphism. Seven restriction patterns were found when using Alu I, and nine were found with Hha I; 12 different alleles were obtained when these patterns were combined. The findings suggest that this gene could be used in Colombia as a molecular epidemiologic marker for genotyping P. vivax.

Multidrug-resistant Plasmodium vivax associated with severe and fatal malaria: a prospective study in Papua, Indonesia

BACKGROUND

Multidrug-resistant Plasmodium vivax (Pv) is widespread in eastern Indonesia, and emerging elsewhere in Asia-Pacific and South America, but is generally regarded as a benign disease. The aim of the study was to review the spectrum of disease associated with malaria due to Pv and P. falciparum (Pf) in patients presenting to a hospital in Timika, southern Papua, Indonesia.

METHODS AND FINDINGS

Data were prospectively collected from all patients attending the outpatient and inpatient departments of the only hospital in the region using systematic data forms and hospital computerised records. Between January 2004 and December 2007, clinical malaria was present in 16% (60,226/373,450) of hospital outpatients and 32% (12,171/37,800) of inpatients. Among patients admitted with slide-confirmed malaria, 64% of patients had Pf, 24% Pv, and 10.5% mixed infections. The proportion of malarial admissions attributable to Pv rose to 47% (415/887) in children under 1 y of age. Severe disease was present in 2,634 (22%) inpatients with malaria, with the risk greater among Pv (23% [675/2,937]) infections compared to Pf (20% [1,570/7,817]; odds ratio [OR] = 1.19 [95% confidence interval (CI) 1.08-1.32], p = 0.001), and greatest in patients with mixed infections (31% [389/1,273]); overall p < 0.0001. Severe anaemia (haemoglobin < 5 g/dl) was the major complication associated with Pv, accounting for 87% (589/675) of severe disease compared to 73% (1,144/1,570) of severe manifestations with Pf (p < 0.001). Pure Pv infection was also present in 78 patients with respiratory distress and 42 patients with coma. In total 242 (2.0%) patients with malaria died during admission: 2.2% (167/7,722) with Pf, 1.6% (46/2,916) with Pv, and 2.3% (29/1260) with mixed infections (p = 0.126).

CONCLUSIONS

In this region with established high-grade chloroquine resistance to both Pv and Pf, Pv is associated with severe and fatal malaria particularly in young children. The epidemiology of P. vivax needs to be re-examined elsewhere where chloroquine resistance is increasing.