Severe Plasmodium vivax malaria: fact or fiction?

Severe Plasmodium vivax infection in Korea

Background

Although severe malaria by Plasmodium vivax has been increasingly reported, there are marked variations in the type and rate of the complications by geographic area. This is possibly because of the presence of concurrent falciparum malaria or bacteraemia, and of differences in underlying immune status among the infected subjects. Furthermore, published studies on P. vivax in temperate regions are limited. The present study investigated severe vivax malaria in Korea, where only vivax malaria occurs. Hence, other compounding factors are rare. Additionally, most of the patients are possibly non-immune to this malarial disease.

Methods

Adults with vivax malaria observed in one 860-bed university hospital from January 2006 to December 2012 were retrospectively evaluated. Seventeen patients who had travelled overseas within 6 months before the presentation of malaria were excluded. Severe vivax malaria was diagnosed according to World Health Organization criteria. Other complications were also investigated.

Results

Two-hundred and ten patients were enrolled, of which 88 (41.9%) were treated as inpatients and the remainder as outpatients. Eleven patients were treated in an intensive care unit; among them, five patients received mechanical ventilation, and one needed extracorporeal membrane oxygenation therapy (ECMO) additionally. Severe vivax malaria was identified in 44 patients (21.0%), and the most common severe complication was pulmonary manifestation (40/188, 21.9%), which was followed by cerebral malaria (5/210, 2.4%), shock (4/210, 1.9%), spontaneous bleeding (3/210, 1.4%), metabolic acidosis (3/210, 3.5%) and acute kidney injury (2/210, 1.0%). Unusual complications, such as splenic infarction (ten patients) and retinal haemorrhage (two patients) were sometimes observed. There were no deaths, but the case involving ECMO was potentially fatal.

Conclusions

Plasmodium vivax infection can be severe to be fatal and is frequently associated with various complications in non-immune adults. The frequency of each complication seems to differ from other countries. Hence, further investigation is needed to elucidate the causes and mechanisms responsible for these differences.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-1684-4) contains supplementary material, which is available to authorized users.

Imported Plasmodium vivax malaria with severe thrombocytopaenia: can it be severe malaria or not?

Background

Thrombocytopaenia is the most frequent malaria-associated haematologic alteration observed with all five Plasmodium parasites causing disease in humans. Although not included in the World Health Organization criteria for severe Plasmodium falciparum malaria, severe thrombocytopaenia has been increasingly mentioned as an indicator of P. vivax malaria severity.

Case

Here, it is described a case of imported P. vivax malaria in a 37-year old man from Pakistan who presented with severe thrombocytopaenia (5 × 10⁹/L). He was admitted to the intensive care unit and initially treated with a 1-day course of intravenous quinine followed by oral chloroquine and primaquine. The patient’s platelet count increased as early as 4 hours after treatment inception and the clinical course was favourable and uneventful.

Discussion

This case report, along with a review of published cases focusing on the relationship between thrombocytopaenia and severe P. vivax malaria, suggests that the prognostic role of severe thrombocytopaenia is ambiguous in absence of severe haemorraghic complications and its use as diagnostic criterion of malaria severity may lead to overestimation of severe P. vivax malaria cases.

Conclusion

Due to the lack of high quality studies it is at present unclear if severe thrombocytopaenia in the setting of P. vivax malaria should be considered indicative of severe malaria.

The prognostic utility of bedside assessment of adults hospitalized with malaria in Myanmar: a retrospective analysis

Background

Data collected in clinical trials have been used to develop scoring systems that identify adults with malaria at greatest risk of death. One of these, the RCAM score, can be simply determined by measuring a patient’s Glasgow Coma Score and respiratory rate on admission to hospital. However the safety of using the RCAM score to define high-risk patients has not been assessed outside of the clinical trial setting.

Methods

A retrospective audit of medical records of all adults admitted with a diagnosis of malaria to two tertiary referral hospitals in Lower Myanmar in 2013 was undertaken. An RCAM score was calculated in all patients and related to their subsequent clinical course.

Results

The recent decline in malaria hospitalizations at both sites continued in 2013. During the year 90 adults were hospitalized with malaria; 62 (69%) had Plasmodium falciparum mono-infection, 11 (12%) had Plasmodium vivax mono-infection, 17 (19%) had mixed infection. All seven (7.7%) deaths occurred in patients infected with P. falciparum. An admission RCAM score <2 identified all the patients that would survive to discharge (positive predictive value (95% confidence interval (CI)) 100% (94.9-100%) and also predicted a requirement for less supportive care: 9/70 (13%) patients with an admission RCAM score <2 required supportive care (blood transfusion, vasopressor support or oxygen supplementation) during their hospitalization compared with 12/20 (60%) patients with an admission RCAM score ≥2 (p < 0.0001). No patient with P. vivax mono-infection required supportive care during their hospitalization. Patients with an oxygen saturation ≤95% on room air on admission were more likely to die before discharge (odds ratio 17.3 (95% CI: 2.9-101.2) than patients with a higher oxygen saturation (p = 0.002).

Conclusions

Even outside a clinical trial setting the RCAM score reliably identifies adults with malaria who are at greatest risk of death and can be safely used in the initial triage and management of these patients.

A descriptive study of 16 severe Plasmodium vivax cases from three municipalities of Colombia between 2009 and 2013

BACKGROUND

Plasmodium vivax, the most geographically distributed cause of malaria, accounts for more than 70% of cases in the Americas. In Colombia, P. vivax was responsible for 67.3% of cases in the last five years. Despite vivax malaria impact worldwide, historically it has been neglected and considered to be a benign disease. In the last decade medical literature reports have emerged countering this benign outlook. This study pretends to describe the clinical and paraclinical profile of severe vivax malaria cases hospitalized in Tumaco, Cali, Buenaventura between 2009 and 2013, to contribute to the knowledge regarding the behaviour and clinical expression of this disease.

METHODS

This is a descriptive, retrospective case-series study of 16 severe malaria vivax cases, hospitalized between 2009 and 2013, in Colombian municipalities of Tumaco, Buenaventura and Cali. Severe malaria vivax cases were defined using criteria adapted from the national guidelines. Descriptive analyses of reason for consultation, signs and symptoms, diagnosis, treatment, paraclinical characteristics, complications, and time hospitalized, were conducted.

RESULTS

Sixteen cases of severe P. vivax were analysed. Fever, chills and headache were shown to be the main admission symptoms. Elevation of total bilirubin levels in 18.75%, and severe thrombocytopaenia in 25% of cases were the main complications presented during hospitalization. All cases responded to treatment, there were no deaths.

CONCLUSIONS

The following questions derived from this study could be the basis for future research: 1) Does the time to consultation have an impact on the number of days hospitalized and how cases progress during hospitalization, 2) Are the severity criteria in WHO guidelines sensitive enough to be used in clinical practice compared to national guidelines, and 3) How does malnutrition contribute to anaemia in malaria-endemic regions.

Pediatric cerebral malaria: a scourge of Africa

Cerebral malaria, defined as an otherwise unexplained coma in a patient with Plasmodium falciparum parasitemia, affects up to 1 million people per year, the vast majority of them being children living in sub-Saharan Africa. Despite optimal treatment, this condition kills 15% of those affected and leaves 30% of survivors with neurologic sequelae. The clinical diagnosis is hampered by its poor specificity, but the presence or absence of a malarial retinopathy in cerebral malaria has proven to be important in the differentiation of underlying coma etiology. Both antimalarials and intense supportive care are necessary for optimal treatment. As of yet, clinical trials of adjunctive therapies have not improved the high rates of mortality and morbidity. Survivors are at high risk of neurologic sequelae including epilepsy, neurodisabilities and cognitive–behavioral problems. The neuroanatomic and functional bases of these sequelae are being elucidated. Although adjunctive therapy trials continue, the best hope for African children may lie in disease prevention. Strategies include bednets, chemoprophylaxis and vaccine development.