A 29-year-old man is brought to the emergency department by concerned friends because of altered mental status for the past day. The friends report that they recently returned from a two-week vacation. Over the past few days, the patient began to complain of headaches, fever and a stiff neck. Over the last day, he started to lose his balance and become very confused. The patient's toxicology screen comes back negative for opioids, ethanol, barbiturates, benzodiazepines and marijuana. Despite adequate care in the emergency department, the patient expires 5 hours later.
A) Swimming in fresh water; Naegleria fowleri
This question describes a rapid decline due to the “brain eating amoeba,” Naegleria fowleri. This organism, which lives in fresh water can, invade the central nervous system via the cribriform plate if freshwater is exposed to human nostrils such as in swimming or using a neti pot. Symptoms can include those that are common in meningitis such as headache, fever, neck stiffness, and nausea. It progresses to encephalitis-like symptoms of altered mental status. Due to the destruction of brain tissue, this disease is rapidly fatal.
Answer choice B: Travel to East Asia; Toxoplasma gondii, is incorrect. Toxoplasma gondii can cause encephalitis that presents similarly to the patient in the vignette. However, it is more likely in a patient with AIDS whose CD4 count is below 100 cells/mm3. A cause of meningoencephalitis that could have been linked to travel to East Asia is Japanese encephalitis virus.
Answer choice C: Travel to Latin America; Trypanosoma cruzi, is incorrect. Trypanosoma cruzi is the cause of Chagas disease, which is characterized by an acute and chronic phase. During the acute phase, which lasts 8-12 weeks, patients have nonspecific symptoms such as malaise, fever, and anorexia or are asymptomatic. Severe acute disease occurs in <1% of patients and includes acute myocarditis, pericardial effusion, and meningoencephalitis.
Answer choice D: Travel to Latin America; Zika virus, is incorrect. Zika is endemic to Latin America, but most young healthy individuals who become infected are asymptomatic. Spread of Zika to a pregnant mother can lead to birth defects such as microcephaly.
Key Learning Point
Naegleria fowleri lives in fresh water and may invade the central nervous system through the nostrils and cribriform plate, resulting in high fever, nausea, and headache with progression to behavioral abnormalities, seizures, and altered mental status. The mortality rate is very high.
