Delayed diagnosis of severe falciparum malaria in a patient presenting with acute gastroenteritis in West Texas

Abstract

Falciparum malaria is a life-threatening infection that affects both people in endemic areas and people who travel to endemic areas. Malaria in exceedingly rare in West Texas, but the initial recognition and prompt initiation of antimalarial treatment are crucial in managing malaria. Here we present a case of a 31-year-old woman who was initially diagnosed with acute gastroenteritis and was later found to have cerebral malaria.

Malaria is an acute illness caused by the parasite Plasmodium carried by Anopheles mosquitoes. According to the World Health Organization, there were approximately 241 million cases of malaria worldwide in 2020. Symptoms include fever, headache, and chills. Malaria can cause additional severe symptoms, including altered mental status, respiratory distress, shock, acute kidney injury, and death.¹

CASE DESCRIPTION

A healthy 31-year-old woman of African descent presented to the hospital with fever, nausea, vomiting, and diarrhea for 1 week. The patient was diagnosed with food poisoning and was admitted to the hospital due to severe diarrhea and hypotension. She was discharged after 24 hours following the resolution of her symptoms.

She presented to the emergency department again later that day with high-grade fever, hypotension, and new-onset worsening headache. Further history revealed that 2 weeks before the onset of symptoms she had traveled to Cameroon to visit family; she did not take any chemoprophylaxis against malaria and had sustained mosquito bites. She was tachycardic and had slight neck stiffness, but was oriented to person, place, and time. Laboratory tests on admission showed hemolytic anemia and thrombocytopenia (white blood cell count 4.9 k/µL, hemoglobin 6.7 g/dL, hematocrit 20.9%, reticulocyte count 3.5%, and platelet count 43 k/µL) with mild transaminitis.

The patient was started on ceftriaxone and ampicillin for empiric meningitis coverage and atovaquone-proguanil for empiric malaria therapy while a malaria smear was pending. Within 12 hours of admission, her mental status declined; she was delirious and demonstrated worsening neck stiffness. A computed tomography scan of the head without contrast showed no intracranial pathology. Lumbar puncture was performed, and the cerebrospinal fluid analysis was unremarkable. A malarial blood smear was positive for Plasmodium falciparum with >60% parasite burden (Figure 1). The Centers for Disease Control and Prevention was contacted and artesunate was requested. The patient’s mental status improved after two doses of artesunate. However, she developed a fever of 101.2°F, as well as hypoxemia (oxygen saturation 95% on nonrebreather 10 L/min), tachycardia (heart rate 115 beats/min), and pulmonary edema with bilateral pleural effusion and required intubation despite a decrease in her malarial parasitemia. She was successfully extubated after 24 hours, was switched to an oral artemisinin course which she completed, and was discharged on oral primaquine to take for 14 days to avoid relapsing in case she had co-infection with P. vivax or P. ovale.

Figure 1.

High parasite burden with >60% of P. falciparum malaria. Note the multiply-infected red blood cells, some appliqué forms, and some classic “head phone” forms.

DISCUSSION

Texas Health and Human Services noted 1144 reported cases of malaria in the state from 2009 to 2018 (trending up every year), with P. falciparum being the most common species in 61% of Plasmodium cases.² Malaria is a frequent cause of fever in a returning traveler and can have variable symptoms, including just gastrointestinal symptoms, as initially occurred in our patient. Our case illustrates the importance of obtaining travel history from a patient with fever, as malaria can have an incubation period of up to 30 days.³ Acute pulmonary edema leading to acute respiratory distress is a well-known complication of severe malaria, occurring in up to 25% of adult cases, and is observed in 4% to 18% of patients with uncomplicated malaria.^3,4

Cerebral malaria is a rare complication of malaria occurring in approximately 1200 per 100,000 persons per year in endemic areas of Africa.⁵ The underlying pathophysiology remains poorly understood. However, previous studies have hypothesized that mature Plasmodium in infected erythrocytes bind to the vascular endothelium in many organs.⁶ This leads to inflammation and endothelial dysfunction in the small vessels, including the lung and central nervous system.⁷ Brain autopsy studies have shown cerebral edema with congested vessels containing numerous parasitized red blood cells with malarial pigment filling in the vascular lumen.

In summary, malaria must always be suspected in people who have a history of recent travel to endemic areas. Falciparum malaria is a virulent malaria subtype that can present as an uncomplicated or severe infection. Prompt antimalarial therapy is an important step in preventing morbidity and mortality in severe malaria. Although artesunate has been widely used and is approved by the Food and Drug Administration, it is available only through the Centers for Disease Control and Prevention, and this can result in delay of optimal treatment due to logistical issues, especially in more rural areas. Hence, clinicians should consider interim treatment with oral antimalarial drugs while waiting for artesunate.