Naegleria fowleri is a free-living ameba parasite. It is designated free-living because it can survive and replicate without requiring a host. This organism is found worldwide usually in bodies of water with relatively high temperatures. In endemic areas the organism can rarely be isolated from healthy individuals and such individuals often have antibodies to the organism (1). Occasionally (about 100 cases in the United States) a devastating rapidly fatal primary amebic meningoencephalitis occurs in children and young adults with a history of diving into lakes, ponds or swimming pools that have not been adequately chlorinated. The organism presumably gains access to the central nervous system via the olfactory epithelium, migrates to the cribiform plate then entering the brain. The incubation period between exposure and clinical manifestation varies from 1 day to 1 week. The patient presents with headache, fever, stiff neck and nausea and vomiting. Progressive neurological deterioration, coma and death occur within a few days in 95% of cases. The cause of death is brain herniation usually due to increased intra-cranial pressure (2). There are no reports of extra-CNS infections with this agent.
In the past few years, increased numbers of cases have been reported from Florida, Texas and Arizona. Because of the infectious nature of the death, organs have been thought to be unusable for transplantation. There is one prior case of such organs being used prior to knowing the Naegleria diagnosis (3).
We report a case of a 12-year-old male donor in Texas who had confirmed N. fowleri infection. The pre-mortem diagnosis was made based on motile amoebae in cerebrospinal fluid and confirmed by the Texas State Parasitology Laboratory. The organs were offered to multiple local and national transplant centers. Because of the perceived risk of infection for potential recipients, the offers were declined. Based on the epidemiology of N. fowleri infection as an exclusively central nervous system infection without systemic manifestations, we accepted both kidneys at our center. After informed consent by the transplant physicians from both patients, the kidneys were transplanted into a 29-year-old male with severe malignant hypertension and a 46-year-old male with IgA nephropathy. Despite cold ischemia times of 36 and 39 h, the kidneys functioned promptly and at 180 days posttransplant had serum creatinines of 1.2 and 1.4, respectively, with no evidence of meningoencephalitis. Thymoglobulin induction followed by mycophenolate mofetil, tacrolimus and prednisone were used in both patients. At other centers: The pancreas was transplanted into a 38-year-old male. The graft failed due to thrombosis without evidence of infection. The liver was used in an 18-year-old male who is doing well at 180 days posttransplant with no evidence of infection or complications. The right lung was used in a 63-year-old male with no complications and no evidence of infection. No attempt to perform serologies pre- and/or posttransplant was made in any recipient.
Although this anecdote cannot be generalized, this unusual cause of brain death does not absolutely preclude successful organ transplantation. Absence of infection outside the CNS at 6 months follow-up posttransplant is reassuring. A better indicator of whether organs are free of ameba is needed. Use of pretransplant rapid PCR test of donor tissues or CSF may prove useful (4). Questions remain about why this infection is not more common given the number of people who swim in potentially infected water and why children and young adults seem to be preferentially affected. It may be due to the fact that the organism needs to be introduced into the brain at high pressures and activities such as cliff diving and water skiing are generally undertaken by the young. These unanswered questions do not absolutely preclude using organs from donors with confirmed Naegleria infections with proper consents in light of the known brain localization of this devastating infection. With global warming this source of donor organs could increase.