Retinal haemorrhage in vivax malaria

Retinopathy Secondary to Uncomplicated Plasmodium vivax Malaria

To report a case of bilateral malarial retinopathy secondary to uncomplicated Plasmodium vivax malaria. A 45-year-old male patient presented with sudden onset of diminution of vision both eyes and was treated for P. vivax malaria 1 week before the ocular symptoms. Dilated fundus examination revealed multiple intraretinal (dot-blot, flame shaped) hemorrhages, cotton-wool spots, and areas of retinal whitening predominantly involving the posterior pole both eyes, with features being more severe in left eye. Optical coherence tomography revealed bilateral subfoveal neurosensory detachments. Retinopathy is typically rare in the settings of P. vivax malaria, albeit commonly seen in patients with cerebral malaria (Plasmodium falciparum). [Ophthalmic Surg Lasers Imaging Retina. 2021;52:50-51.].

Comparative ophthalmic assessment of patients receiving tafenoquine or chloroquine/primaquine in a randomized clinical trial for Plasmodium vivax malaria radical cure

PURPOSE

Ophthalmic safety observations are reported from a clinical trial comparing tafenoquine (TQ) efficacy and safety versus sequential chloroquine (CQ)/primaquine (PQ) for acute Plasmodium vivax malaria.

METHODS

In an active-control, double-blind study, 70 adult subjects with microscopically confirmed P. vivax malaria were randomized (2:1) to receive 400 mg TQ × 3 days or 1500 mg CQ × 3 days then 15 mg PQ × 14 days.

MAIN OUTCOME MEASURES

clinically relevant changes at Day 28 and Day 90 versus baseline in the ocular examination, color vision evaluation, and corneal and retinal digital photography.

RESULTS

Post-baseline keratopathy occurred in 14/44 (31.8%) patients with TQ and 0/24 with CQ/PQ (P = 0.002). Mild post-baseline retinal findings were reported in 10/44 (22.7%) patients receiving TQ and 2/24 (8.3%) receiving CQ/PQ (P = 0.15; treatment difference 14.4%, 95% CI - 5.7, 30.8). Masked evaluation of retinal photographs identified a retinal hemorrhage in one TQ patient (Day 90) and a slight increase in atrophy from baseline in one TQ and one CQ/PQ patient. Visual field sensitivity (Humphrey™ 10-2 test) was decreased in 7/44 (15.9%) patients receiving TQ and 3/24 (12.5%) receiving CQ/PQ; all cases were < 5 dB. There were no clinically relevant changes in visual acuity or macular function tests.

CONCLUSIONS

There was no evidence of clinically relevant ocular toxicity with either treatment. Mild keratopathy was observed with TQ, without conclusive evidence of early retinal changes. Eye safety monitoring continues in therapeutic studies of low-dose tafenoquine (300 mg single dose).

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT01290601.

Retinopathy of vivax malaria in adults and its relation with severity parameters

Malarial retinopathy is a set of retinal signs in severe malaria due to falciparum malaria. With increased recognition of severe manifestations of vivax malaria, a systematic study to evaluate retinal changes in vivax malaria could elaborate our knowledge about this neglected entity. This observational study included retinal examination of 104 adult patients (>14 years) with varying severity of vivax malaria admitted to a tertiary care center during peak seasons of 2012 and 2013. Thirty-eight percent of severe cases had a retinal sign as compared to 6% of non-severe cases (p < 0.01). No statistically significant effect of residence or age on the presence of retinopathy was noted. Females were found to be more prone to develop a retinal sign (p < 0.01). Presence of retinal signs was significantly associated with anemia and jaundice. No statistical association was noted for retinal signs to be present in either renal dysfunction or altered thrombocytes count. The most common signs were arteriovenous changes, present in eight cases (19%) of severe malaria and three cases (5%) of non-severe malaria. Retinal hemorrhage was present in five cases (12%) of severe malaria and no case of non-severe malaria. Both superficial and deep hemorrhages were seen including white-centered hemorrhages. Other signs included cotton wool spots, hard exudates, blurred disk margins with spontaneous venous pulsations and bilateral disk edema. A correlation between retinal signs and severity parameters was drawn from the study. This is the first systemic study to evaluate the retinal changes in vivax malaria. Larger prospective studies should be done for further knowledge regarding retinal changes in vivax malaria, especially severe disease. Apart from its clinical significance, it might lead to a better understanding of the pathogenesis of the systemic disease of vivax malaria.

Retinal Hemorrhages in Severe Non-cerebral Plasmodium vivax Malaria in an Adult

Malaria is the most important parasitic diseases of humans and one of the leading causes of morbidity and mortality in tropical countries. Earlier Plasmodium vivax was considered as a benign infection, but now it is recognized as a cause of severe malarial disease. It causes severe malarial disease similar to those as Plasmodium falciparum including cerebral malaria, severe anaemia, severe thrombocytopenia, hepatic dysfunction, shock, acute respiratory distress syndrome (ARDS), acute renal failure, and pulmonary oedema. Malarial retinopathy includes retinal whitening, vessel changes, retinal hemorrhages and papilledema. However, retinal hemorrhages are very rare in Plasmodium vivax infestation. Hereby, we report a case of 30-year-old man, who presented with fever with chills and diminution of vision. He was found to have Plasmodium vivax infection with retinal hemorrhages. He was treated successfully with artisunate, primaquine and doxycycline, completely recovered after one month.

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-associated acute kidney injury, India, 2010-2011

Plasmodium vivax is causing increasingly more cases of severe malaria worldwide. Among 25 cases in India during 2010–2011, associated conditions were renal failure, thrombocytopenia, jaundice, severe anemia, acute respiratory distress syndrome, shock, cerebral malaria, hypoglycemia, and death. Further studies are needed to determine why P. vivax malaria is becoming more severe.

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.

Renal cortical necrosis and acute kidney injury associated with Plasmodium vivax: a neglected human malaria parasite

Plasmodium vivax is causing increasingly more cases of severe malaria worldwide. There is an urgent need to reexamine the clinical spectrum and burden of P. vivax so that adequate control measures can be implemented against this emerging but neglected disease. Herein, we report a case of renal acute cortical necrosis and acute kidney injury (AKI) associated with P. vivax monoinfection. Her initial serum creatinine was 7.3 mg/dL on admission. Modification of Diet in Renal Disease (MDRD) Study glomerular filtration rate (GFR) value was 7 mL/min/1.73 m(2) (normal kidney function-GFR above 90 mL/min/1.73 m(2) and no proteinuria). On follow-up, 5 months later, her SCr. was 2.43 mg/dl with no proteinuria. MDRD GFR value was 24 mL/min/1.73 m(2) suggesting severe chronic kidney disease (CKD; GFR less than 60 or kidney damage for at least 3 months), stage 4. Our case report highlights the fact that P. vivax malaria is benign by name but not always by nature. AKI associated with P. vivax malaria can lead to CKD. Further studies are needed to determine why P. vivax infections are becoming more severe.

Population dynamics of a pathogen: the conundrum of vivax malaria

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

Retinal hemorrhage in Plasmodium vivax malaria

Retinal hemorrhage is a frequently observed sign in Plasmodium falciparum infection. In Plasmodium vivax infection, however, retinal hemorrhage is very rare; only five cases have been reported in the literature. In this case report, we review the literature and the case of 52-year-old man who had retinal hemorrhages in P. vivax infection. We analyzed the structural characteristics of the lesions using fluorescein angiography and spectral-domain optical coherence tomography. Physicians should be aware of the possibility of retinal hemorrhage in malaria patients, even those with P. vivax infection, and should consider a diagnosis of malaria in a patient with unexplained retinal hemorrhage and fever.

[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".

A case of myocarditis associated with Plasmodium vivax malaria

Cardiac complications in malaria have been infrequently associated with Plasmodium falciparum infections. However, myocarditis associated with Plasmodium vivax malaria has not been reported in the literature. We observed an unusual case of vivax malaria that was complicated by myocarditis.

Host control of malaria infections: constraints on immune and erythropoeitic response kinetics

The two main agents of human malaria, Plasmodium vivax and Plasmodium falciparum, can induce severe anemia and provoke strong, complex immune reactions. Which dynamical behaviors of host immune and erythropoietic responses would foster control of infection, and which would lead to runaway parasitemia and/or severe anemia? To answer these questions, we developed differential equation models of interacting parasite and red blood cell (RBC) populations modulated by host immune and erythropoietic responses. The model immune responses incorporate both a rapidly responding innate component and a slower-responding, long-term antibody component, with several parasite developmental stages considered as targets for each type of immune response. We found that simulated infections with the highest parasitemia tended to be those with ineffective innate immunity even if antibodies were present. We also compared infections with dyserythropoiesis (reduced RBC production during infection) to those with compensatory erythropoiesis (boosted RBC production) or a fixed basal RBC production rate. Dyserythropoiesis tended to reduce parasitemia slightly but at a cost to the host of aggravating anemia. On the other hand, compensatory erythropoiesis tended to reduce the severity of anemia but with enhanced parasitemia if the innate response was ineffective. For both parasite species, sharp transitions between the schizont and the merozoite stages of development (i.e., with standard deviation in intra-RBC development time <or=2.4 h) were associated with lower parasitemia and less severe anemia. Thus tight synchronization in asexual parasite development might help control parasitemia. Finally, our simulations suggest that P. vivax can induce severe anemia as readily as P. falciparum for the same type of immune response, though P. vivax attacks a much smaller subset of RBCs. Since most P. vivax infections are nonlethal (if debilitating) clinically, this suggests that P. falciparum adaptations for countering or evading immune responses are more effective than those of P. vivax.

Malaria: mechanisms of erythrocytic infection and pathological correlates of severe disease

Malaria is an ancient disease that continues to cause enormous human morbidity and mortality. The life cycle of the causative parasite involves multiple tissues in two distinct host organisms, mosquitoes and humans. However, all the clinical symptoms of malaria are a consequence of infection of human erythrocytes. An understanding of the basic mechanisms that govern parasite invasion, remodeling, growth, and reinvasion of erythrocytes and the complex events leading to tissue pathology may yield new diagnostics and treatments for malaria. This approach is revealing a more complete picture of the most serious syndrome associated with this infection-cerebral malaria. We focus on the most recent understanding of the molecular basis of infection, summarize our finding from an ongoing pediatric cerebral malaria autopsy study in Malawi, and integrate these insights to malarial pathology.

A case of symptomatic splenic infarction in vivax malaria

Splenic infarction is a rare complication in malaria cases, and is caused primarily by Plasmodium falciparum. Recently in South Korea, only P. vivax has prevailed since 1993. Although the probability that symptomatic splenic infarction may occur in vivax malaria cases is considered relatively high, there have never been any case reports describing the occurrence of symptomatic splenic infarction in cases of vivax malaria. A 34-year-old man presented with fever that had persisted for 5 days. P. vivax infection was verified using a peripheral blood smear, and chloroquine was utilized to treat the fever successfully. Six days later, the patient developed pain in the left upper abdomen, which was diagnosed as splenic infarction by computed tomography.

An update on the search for a Plasmodium vivax vaccine

Although Plasmodium falciparum is the leading cause of morbidity and mortality due to malaria worldwide, nearly 2.5 billion people, mostly outside Africa, are also at risk from malaria caused by Plasmodium vivax infection. Currently, almost all efforts to develop a malaria vaccine have focused on P. falciparum. For example, there are 23 P. falciparum vaccine candidates undergoing advanced clinical studies and only two P. vivax vaccine candidates being tested in preliminary (Phase I) clinical trials, with few others being assessed in preclinical studies. More investment and a greater effort toward the development of P. vivax vaccine components for a multi-species vaccine are required. This is mainly because of the wide geographical coexistence of both parasite species but also because of increasing drug resistance, recent observations of severe and lethal P. vivax cases and relapsing parasite behaviour. Availability of the P. vivax genome has contributed to antigen discovery but new means to test vaccines in future trials remain to be designed.

[Is Plasmodium vivax still a paradigm for uncomplicated malaria?]

P. vivax is supposed to be involved in benign tertian fever, responsible for a non-complicated disease that could be easily treated by standard antimalarial drug regimen. This could be considered as a long-standing paradigm of a non-virulent malaria parasite. When a patient exhibits severe malaria with the vivax parasite, the issue is often to find falciparum. However, with the implementation of molecular diagnosis, it has becoming more evident that vivax parasites could be involved in severe disease with probably a different pathogenesis. Mixed infections are frequent in various parts of Southeast Asian endemic areas and it was speculated that drugs used to treat falciparum could be involved in the development of vivax drug resistance. How should primaquine be used today for the treatment and prophylaxis of vivax malaria? Considering the re-emergence of vivax malaria in several areas, improving the treatment for this disease is certainly an important issue to avoid late episodes and transmission potential.