Probable Toxic Cause for Suspected Lychee-Linked Viral Encephalitis

To the Editor: Paireau et al. (1) reported a spatiotemporal association between unexplained outbreaks of suspected acute encephalitis in children in northern Vietnam and the harvesting of lychee (litchi) fruit. The clinical, biologic, and immunologic characteristics of the patients suggested a viral etiology (1). However, the lychee-associated acute brain disorder, which has also been reported in Bangladesh and India (Bihar and West Bengal), could also result from ingestion of phytotoxins present in lychee fruit, specifically α-(methylenecyclopropyl)glycine (2), the lower homologue of the neurotoxic L-amino acid hypoglycine (3,4).


Probable Toxic Cause for
To the Editor: Paireau et al. (1) reported a spatiotemporal association between unexplained outbreaks of suspected acute encephalitis in children in northern Vietnam and the harvesting of lychee (litchi) fruit. The clinical, biologic, and immunologic characteristics of the patients suggested a viral etiology (1). However, the lychee-associated acute brain disorder, which has also been reported in Bangladesh and India (Bihar and West Bengal), could also result from ingestion of phytotoxins present in lychee fruit, specifically a-(methylenecyclopropyl)glycine (2), the lower homologue of the neurotoxic L-amino acid hypoglycine (3,4).
As previously described (5), ingestion of the hypoglycine-rich fruit of ackee, a relative of lychee, can induce a dose-dependent toxic hypoglycemic encephalopathy in poorly nourished children. The syndrome is best known from Jamaica, where ackee is widely eaten, and occurs most frequently in 2-to 10-year-old children, who develop severe hypoglycemia and metabolic acidosis. Clinical manifestations of Jamaican vomiting sickness include headache, thirst, sweating, vomiting, lethargy, seizures, coma, and death over a span of hours to days. Patients may be mildly to moderately febrile, and emesis may not be present in all cases. Heavy ingestion of the immature aril (fruit) of ackee (Blighia sapida) or other members of the soapberry family (Sapindaceae), including lychee (Litchi sinensis), rambutan (Nephelium lappaceum), and longan (Dimocarpus longan), by an undernourished child with low glycogen/glucose stores probably has the potential to result in toxic hypoglycemic syndrome.
Assessment of finger-prick blood glucose levels, which may be markedly depressed in children with severe Sapindaceae fruit poisoning, provides a rapid and convenient screening tool to identify suspected cases. Intravenous administration of glucose is the first line of treatment, along with serial monitoring of glucose, serum aminotransferase, and serum creatinine levels. Restoration of body fluid, electrolytes, glucose, and pH balance is the goal of supportive treatment.
Note added in proof. Subsequent to the submission of this letter, a description was published of recent outbreaks of unexplained acute hypoglycemic encephalopathy in young children in Muzaffarpur, Bihar, coinciding with local lychee harvests (6). To the Editor: Myiasis is the infestation of humans or animals with dipterous insect larvae (1). The term pinsite myiasis was recently adopted for a rare and emerging parasitic infection after treatment of open fractures with external metal fixators (pins). Myiasis can also occur as a result of invasion of larvae deposited by flies in wounds adjacent to these fixators (1,2). We describe a patient with pin-site myiasis caused by the Cochliomyia hominivorax screwworm fly associated with external fixators used for treatment of an open fracture of the femur.
In September 2014, a 26-year-old male soldier from the Department of Meta in central Colombia was admitted to a primary medical unit for treatment of an open fracture of the right femur after a traffic accident. The patient had no relevant medical history. After multiple surgical interventions and external fixation of the fracture, he was discharged. Two weeks later, he returned to the medical unit with edema, redness, and warmth in the area surrounding the metallic fixators. At this time, 50 larvae were observed in the surgical wound ( Figure, panel A).
The patient was referred to Hospital Militar Central in Bogota, Colombia, where surgical cleansing of the wound was performed and 30 additional larvae were obtained (Figure, panel B). Extracted larvae were sent to the Parasitology Laboratory of the Universidad Nacional de Colombia in Bogota, Colombia for identification. The larvae were taxonomically classified as those of the C. hominivorax screwworm fly.
Treatment with oral ivermectin and intravenous ampicillin/sulbactam was initiated. The next day, surgical cleansing showed signs of osteomyelitis. A culture of bone tissue was positive for multidrug-susceptible Pseudomonas aeruginosa and Stenotrophomonas maltophilia susceptible to trimethoprim/sulfamethoxazole (TMP/SMX). At this time, antimicrobial drug therapy was changed to intravenous ciprofloxacin (400 mg every 12 h) and oral TMP/ SMX (160/800 mg every 12 h). The patient completed 2 weeks of treatment in the hospital and showed no signs or symptoms of infection or infestation by larvae. He was discharged, prescribed oral TMP/SMX, and followed up by