Prolonged fever and exaggerated hypercoagulopathy in malaria vivax relapse and COVID-19 co-infection: a case report

Coronavirus disease 2019 (COVID-19) often causes atypical clinical manifestations similar to other infectious diseases. In malaria-endemic areas, the pandemic situation will very likely result in co-infection of COVID-19 and malaria, although reports to date are still few. Meanwhile, this disease will be challenging to diagnose in areas with low malaria prevalence because the symptoms closely resemble COVID-19. A 23-year-old male patient presented to the hospital with fever, anosmia, headache, and nausea 1 week before. He was diagnosed with COVID-19 and treated for approximately 10 days, then discharged to continue self-quarantine at home. 2 weeks later, he returned to the hospital with a fever raised intermittently every 2 days and marked by a chilling-fever-sweating cycle. A laboratory test for malaria and a nasopharyngeal swab for SARS CoV-2 PCR were conducted, confirming both diagnoses. The laboratory examination showed markedly elevated D-dimer. He was treated with dihydroartemisinin-piperaquine (DHP) 4 tablets per day for 3 days and primaquine 2 tablets per day for 14 days according to Indonesian National Anti-malarial Treatment Guidelines. After 6 days of treatment, the patient had no complaints, and the results of laboratory tests had improved. This report describes the key points in considering the differential diagnosis and prompt treatment of malaria infection during the pandemic of COVID-19 in an endemic country to prevent the worse clinical outcomes. COVID-19 and malaria may also cause a hypercoagulable state, so a co-infection of those diseases may impact the prognosis of the disease. This case report shows that considering the possibility of a co-infection in a COVID-19 patient who presents with fever can prevent delayed treatment that can worsen the disease outcome. Paying more attention to a history of travel to malaria-endemic areas, a history of previous malaria infection, and exploring anamnesis regarding the fever patterns in patients are important points in making a differential diagnosis of malaria infection during the COVID-19 pandemic.

Malaria is an infectious disease caused by protozoa of the genus Plasmodium, which is transmitted through the bite of an Anopheles mosquito. Malaria infections can cause severe clinical manifestations and death if not promptly diagnosed and treated. There are five species of Plasmodium that cause malaria in humans, with the most deaths caused by Plasmodium falciparum. Plasmodium vivax predominates as a cause of morbidity, while Plasmodium ovale and Plasmodium malariae rarely cause severe malaria. Plasmodium knowlesi primarily infects macaques in Southeast Asia, but humans living around these animals can become infected [5].
Malaria remains a serious global health problem, especially in endemic countries. In 2019, an estimated 229 million malaria cases occurred worldwide, with 3% of all cases caused by Plasmodium vivax, which is the predominant parasite responsible for 51.7% of malaria cases in Southeast Asia, including Indonesia [6]. Patients with malaria will usually experience paroxysmal fever, fatigue, malaise, and myalgia [7]. A co-infection between COVID-19 and malaria is rarely reported, and the mechanism is unclear. It is suggested that a co-infection leads to excess proinflammatory responses and pro-coagulant states that might result in more severe manifestations and poor prognosis. Heightened clinical suspicion is needed to diagnose other infections during the COVID-19 pandemic, especially for patients with a travelling history of malaria-endemic areas. In this case report, we found a confirmed COVID-19 patient diagnosed with malaria.

Case presentation
A 23-year-old male patient came to the emergency department at Universitas Airlangga Hospital presenting fever, anosmia, headache, and nausea 5 days before. He was diagnosed with COVID-19, confirmed by the RT-PCR amplification of SARS-CoV-2 virus nucleic acid on a nasopharyngeal swab. The patient had abnormal laboratory findings, such as lymphopenia, neutrophilia, thrombocytopenia, and high CRP, with a normal chest X-ray (Fig. 1). The patient was treated with Favipiravir at 1600 mg per 12 h on day 1, then 600 mg per 12 h on day 2-day 5, intravenous drip of paracetamol 1000 mg every 8 h, oral vitamin C 500 mg per 8 h, and oral vitamin D 1000 IU per day according to Indonesian national COVID-19 treatment guidelines. After 10 days of treatment, the patient was still PCR positive despite no complaints. He was then discharged to continue selfquarantine at home.
He returned to the hospital two weeks later with general weakness and fever. The fever did not resolve during his self-quarantine, was raised intermittently every 2 days, and was marked by a chilling-fever-sweating cycle. The fever temperature measured was around 39.7°-40 °C. The fever improved when the patient took paracetamol, but the fever returned 6 h later. The fever was accompanied by malaise and muscle pain. The next day the patient was fever-free and able to carry out his daily activities. The physical examination revealed a body temperature of 38 °C, a blood pressure of 112/72 mmHg, a heart rate of 93 bpm, a respiratory rate of 20 breaths/ minute, and oxygen saturation of 98% under ambient air. The patient weighs 65 kg with a height of 170 cm (BMI 22.5 kg/m 2 ). Other physical examinations were normal.
The laboratory results reflected a white blood cell count of 8750/µL with 76.3% neutrophils, 13.5% lymphocytes, and 0.6% eosinophils. Haemoglobin level and platelet counts were 12.2 g/dL and 231,000/µL, respectively. CRP and D-dimer levels were 41.51 mg/L and 9.52 mg/L, respectively. Serum electrolytes and renal function tests were normal, with urea and creatinine serum 6 mg/dL and 0.4 mg/dL, respectively. The liver enzymes test was normal, with ALT being 14 IU/L and AST being 25 IU/L. Electrocardiography showed normal sinus rhythm and axis. The chest X-ray was unremarkable (Fig. 2). The RT-PCR amplification of the SARS-CoV-2 virus nucleic acid test from the nasopharyngeal swab was still positive.
From the previous history, he said that he traveled to Timika District, Papua, for office work for the last 2 years. In May 2021, the patient was infected with P vivax, with initial symptoms including fever, dizziness, nausea, and muscle pain. The patient was treated until declared fully cured. A laboratory test for malaria was performed. The rapid malaria test was positive for PAN antigen, and microscopic diagnosis on blood smear revealed Plasmodium vivax on ring form, trophozoite, and gametocyte stage (Figs. 3,4,5). Based on anamnesis, physical examination, and laboratory results, the patient was diagnosed with confirmed COVID-19 with hypercoagulopathy and malaria vivax relapse (Fig. 6). According to Indonesian National Guidelines for Antimalarial Treatment [8], he was treated with dihydroartemisinin-piperaquine (DHP) 4 tablets per day for 3 days and primaquine 2 tablets per day for 14 days. The G6PD status was not tested. The patient was given an intravenous drip of paracetamol 1000 mg every 8 h and a subcutaneous injection of heparin 5000 IU every 12 h during treatment. After six days of treatment, the patient had no complaints, and the results of laboratory tests had improved. The patient was discharged from the hospital, continued self-isolation at home, and followed up with the internal medicine outpatient clinic two weeks later. Furthermore, the patient was called later and reported feeling healthy with no complai nts.

Discussion
Indonesia is one of the tropical countries in the world still facing a high risk of malaria. Approximately 80% of cities or districts in Indonesia are endemic to malaria, one of   which is Papua. Based on the data from Annual Parasite Incidence (API) in 2019, the number of positive cases of malaria in Papua is 64.03% per 1000 population [9]. Plasmodium vivax malaria still causes significant morbidity in endemic areas. Reactivation of the dormant stage of hypnozoite can cause P. vivax relapse [10]. A single inoculation by a female Anopheles mosquito can be followed by multiple relapses [11].
Plasmodium vivax is capable of undergoing early and frequent relapses. In addition to blood-stage parasite replication, P. vivax has a dormant stage of hypnozoites that can persist in the liver and reactivate to cause relapses weeks or even years later [12]. This reactivation may be triggered by the host's inflammatory response to systemic illnesses or parasitic and bacterial infections, but not viral infections [13]. The estimated ratio of P. vivax relapses to total infections is 76-90% in the Papua New Guinea cohort study and 79% in the Thailand cohort study [12]. Based on the study conducted by Chu et al. P. vivax parasitaemia recurrences, mainly relapses, occurred in 377 from 644 (59%) patients treated with artesunate, chloroquine, or chloroquine-primaquine. A history of the previous malaria was more common in patients with recurrences (61%) than without recurrence (39%). About 90% of all P. vivax recurrences occurred by week 16 following treatment. Primaquine, as the radical cure with an estimated efficacy of 92%, would reduce the risk of  relapses and lessen the significant burden of morbidity caused by P. vivax [14].
The pathophysiology behind the co-infection of COVID-19 with P. vivax malaria remains unclear. It is unknown whether SARS-CoV-2 infection reduces the immunity that leads to malaria reactivation or if complications from malaria increase the susceptibility to get COVID-19 [15]. Based on the disease course, this patient was suspected of having reactivation of P. vivax infection due to COVID-19 infection. The mechanism that caused the reactivation is still unclear and may be attributed to the cytokine response to COVID-19. There is still a possibility of natural reactivation or reinfection not related to COVID-19 infection that cannot be completely ruled out [16]. The excessive proinflammatory cytokine response generated in co-infection of COVID-19 and Malaria can worsen the prognosis [17].
The patient was also suspected of having prolonged viral shedding of SARS-CoV-2; the PCR was still positive on day 38 after symptom onset. This phenomenon may be attributable to several risk factors, including male sex, disease severity, delayed hospital admission, underlying comorbidities, and a higher pro-inflammatory cytokine level [18][19][20]. In a large Italian cohort study, Mondi et al. stated that pro-inflammatory marker changes, especially lymphopenia, and elevated D-dimer, were strongly associated with prolonged viral shedding [19]. A higher neutrophil count and CRP were also mentioned in a report by Gao et al. as independent risk factors of prolonged viral shedding found in COVID-19 patients with bacterial co-infection [20]. Rather than bacterial infection, the abnormal proinflammatory cytokine and infection markers related to prolonged SARS-CoV-2 RNA shedding in this case were exaggerated by malaria vivax relapse.
Early symptoms of SARS-CoV-2 infection, such as fever, fatigue, and myalgia, similar to those of malaria, can lead to delayed diagnosis, especially in malariaendemic areas [16]. In contrast to severe malaria, which is often caused by P. falciparum, where neurological symptoms are predominant and more severe symptoms such as loss of consciousness, signs of focal neurological abnormalities, and severe anaemia can further narrow the diagnosis of malaria. The results of blood tests can also be confusing. Therefore, a diagnostic test for both malaria and COVID-19 is crucial. The principal diagnosis of malaria to date is the microscopic examination to detect the presence of Plasmodium at all stages. However, the sensitivity and specificity of this examination are highly dependent on the examiner's subjectivity. If a microscopy test is not available, malaria rapid diagnostic test (RDT) can be an alternative to confirm the diagnosis. Another method using a PCR is more sensitive than microscopy, but the results take too long, so it is rarely used [21]. Plasmodium spp and COVID-19 have incubation periods that are not much different. For COVID-19, the incubation period reaches 14 days from exposure with a median value of 4-5 days, while for malaria, the incubation period varies from 7 to 30 days [21]. Hence, it is essential to gain a thorough anamnesis in differentiating these two diagnoses.
Hypercoagulopathy is common in COVID-19 patients, especially in those with severe disease [22]. SARS-CoV-2 induces tissue factor expression, a primary initiator of the coagulation cascade, by cytokines produced by inflammatory cells. Moreover, SARS-CoV-2 causes endothelial dysfunction through an angiotensin-converting enzyme-2 (ACE-2) receptor expressed on the surface of vascular endothelial cells and induces neutrophil extracellular traps (NETs) release, which activates the coagulation pathways and platelet [23]. Abnormal coagulation parameters such as elevated D-dimer and fibrin degradation product levels and prolonged prothrombin time are related to a poor outcome. The most common manifestations of COVID-19 hypercoagulopathy are venous thromboembolism and arterial thrombotic complications, including pulmonary embolism and stroke [3]. COVID-19 patients are at risk for developing disseminated intravascular coagulation (DIC), pulmonary haemorrhage, and thrombosis. Thrombocytopenia associated with a higher risk of severe COVID-19 is suspected to be caused by platelet consumption in the lungs and infected haematopoietic stem cells and megakaryocytes [24].
Malaria is also strongly associated with a hypercoagulopathy condition through activation of the coagulation cascade triggered by proinflammatory cytokines [e.g., tumour necrosis factor (TNF) and interleukin (IL)-6] [25]. The most common coagulopathy condition is microthrombotic complications, besides thrombosis of large vessels, including cerebral venous thrombosis and pulmonary embolism. Thrombocytopenia is a common finding (60-80%) that may be due to impaired coagulation, splenomegaly, bone marrow disorders, antibodymediated platelet destruction, oxidative stress, and platelet aggregation. DIC and bleeding are related to high mortality, occurring only in severe malaria. Tissue factors released from damaged vascular endothelial cells and the lysis of activated platelets contribute to the development of a pro-coagulant state similar to the underlying mechanism in COVID-19 [26]. Therefore, Plasmodium spp. and SARS-CoV-2 co-infection could lead to severe coagulopathy and worse outcomes than with either infection alone. In this case, the patient had a high risk of mortality due to hypercoagulopathy, characterized by markedly increased D-dimer levels which was also aggravated by malaria vivax relapse. Regarding this condition, thromboprophylaxis has a crucial role in reducing the risk of thrombotic events.
There was also some similar report regarding malaria and COVID-19 co-infection, as shown in Table 1. The first case report was described by Sardar et al. [17] in Qatar as a possible P. vivax reactivation secondary to COVID-19, similar to the case reports presented by Kishore et al. [16] in India and Shahid et al. [11] in Qatar. Ray et al. reported a concomitant infection between malaria vivax and COVID-19 in India without suggesting the possibility of P. vivax re-activation [27]. However, this report is the first case of malaria vivax and COVID-19 co-infection in Indonesia that discussed the possibility of P. vivax relapse related to COVID-19 with symptoms of prolonged fever and exaggerated hypercoagulopathy.
Based on World Health Organization recommendations, in terms of facing challenges caused by the COVID-19 pandemic, such as the disruption of the malaria rapid test kits supply, the shortage of health workers and personal protective equipment, as well as the limited facilities of the Intensive Care Unit (ICU), the diagnosis of malaria must always be considered in all cases of fever in malaria-endemic countries [21]. Considering the differential diagnosis of malaria infection other than SARS-CoV-2 infection can reduce the risk of morbidity and mortality due to delayed and inappropriate treatment.
Various clinical trials to determine the appropriate COVID-19 therapeutic regimen are still ongoing. The massive use of hydroxychloroquine to treat COVID-19 in Malaria endemic areas will further increase the risk of anti-malarial drug resistance [17]. In this case report, the patient was treated with Favipiravir, a nucleoside analogue antiviral efficacious in various clinical trials for treating mild-to-moderate COVID-19 [28]. In a 2021 review study, Zenchenko et al. concluded that nucleoside analogue antivirals could treat a parasitic infection, such as malaria caused by P. falciparum. Meanwhile, studies on the nucleoside analogue antiparasitic effect in vivax malaria are limited [29]. Artemisinin is a very potent anti-malarial drug and can overcome the problem of resistance to quinolones. Artemisinin is also able to inhibit endocytosis more strongly than chloroquine. Artesunate, a semisynthetic derivative of artemisinin, has lately attracted much attention to be tested as a COVID-19 therapy because of its anti-viral and anti-inflammatory effects through inhibition of Nuclear Factor kappa B (NF-kB) downregulation and protein synthesis in the early stages of viral replication [30]. Further research is required to study the role of artemisinin in treating COVID-19 and the prognosis of COVID-19 co-infection with malaria.

Conclusion
This case report shows that considering the possibility of a secondary infection diagnosis other than COVID-19 in a patient who presents with fever can prevent delayed treatment that can worsen the disease outcome. Paying more attention to a history of travel to malaria-endemic areas, a history of previous malaria infection, and exploring anamnesis regarding the fever patterns in patients are important points in making a differential diagnosis of malaria infection during the COVID-19 pandemic. Hypercoagulopathy is another phenomenon that needs further analysis in Malaria and COVID-19 co-infection. Further research is required to study the role of artemisinin in treating COVID-19 and the prognosis of COVID-19 co-infection with malaria.