title: Paralytic shellfish poisonings resulting from an algal bloom in Nicaragua.
abstract: BACKGROUND
  During an October 2005 algal bloom (i.e., a rapid increase or accumulation in the population of algae) off the coast of Nicaragua, 45 people developed symptoms of paralytic shellfish poisoning (PSP) and one person died. PSP in humans is caused by ingestion of saxitoxin, which is a neurotoxin often associated with shellfish contaminated by algal blooms. To explore the relationship between the algal bloom and human illnesses, we performed a case-control study of residents living in a coastal island. We administered a standardized clinical questionnaire, sampled locally harvested seafood and algae, and obtained urine samples for saxitoxin testing from symptomatic and asymptomatic persons. PSP case-patients were defined as island residents who developed at least one neurological symptom during the November 4-16 intoxication period. Seafood and algal samples were analyzed for saxitoxins using the receptor-binding assay and high-performance liquid chromatography. Two urine samples were analyzed for saxitoxins using a newly developed immunoassay.
  
  
  RESULTS
  Three shellfish and two algal samples tested positive for saxitoxins. Ten (9%) of 107 participants developed neurological symptoms during the specified time period and five required hospitalization. While 6 (67%) of 9 possible case-patients and 21 (21%) of 98 controls had eaten fish (p=0.008), all case-patients and 17 (17%) of controls had eaten clams (P<0.0001). The saxitoxin concentration in the urine of a hospitalized case-patient was 21 ng saxitoxin/g creatinine compared to 0.16 ng saxitoxin/g creatinine in the single control patient's urine.
  
  
  CONCLUSIONS
  These findings suggest that a bloom of saxitoxin-producing algae resulted in saxitoxin accumulation in local clams and was responsible for the PSP intoxication.
authors.affiliation: Field Epidemiology Training Program, Managua, Nicaragua, USA. lcallejas@asamblea.gob.ni.
authors.forename: Luis
authors.initials: L
authors.lastname: Callejas
authors.affiliation: Field Epidemiology Training Program, Managua, Nicaragua, USA. dra.melendez@yahoo.com.
authors.forename: Ana Cristian Melendez
authors.initials: AC
authors.lastname: Darce
authors.affiliation: Nicaragua Ministry of Health, Managua, Nicaragua, USA. amadorjuan2430@yahoo.com.
authors.forename: Juan Jose
authors.initials: JJ
authors.lastname: Amador
authors.affiliation: U.S. Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, MS A32, Atlanta, GA, 30333, USA. dvj3@cdc.gov.
authors.forename: Laura
authors.initials: L
authors.lastname: Conklin
authors.affiliation: U.S. Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, MS A32, Atlanta, GA, 30333, USA. NGaffga@cdc.gov.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Gaffga
authors.affiliation: U.S. Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, MS A32, Atlanta, GA, 30333, USA. hhs0@cdc.gov.
authors.forename: Helen
authors.initials: H
authors.lastname: Schurz Rogers
authors.affiliation: U.S. Food and Drug Administration, College Park, Maryland, USA. Stacey.Degrasse@fda.hhs.gov.
authors.forename: Stacey
authors.initials: S
authors.lastname: DeGrasse
authors.affiliation: U.S. Food and Drug Administration, College Park, Maryland, USA. sherwood.hall@fda.hhs.gov.
authors.forename: Sherwood
authors.initials: S
authors.lastname: Hall
authors.affiliation: U.S. Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, MS A32, Atlanta, GA, 30333, USA. mee9@cdc.gov.
authors.forename: Marie
authors.initials: M
authors.lastname: Earley
authors.affiliation: U.S. Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, MS A32, Atlanta, GA, 30333, USA. JMei@cdc.gov.
authors.forename: Joanne
authors.initials: J
authors.lastname: Mei
authors.affiliation: U.S. Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, MS A32, Atlanta, GA, 30333, USA. chr1@cdc.gov.
authors.forename: Carol
authors.initials: C
authors.lastname: Rubin
authors.affiliation: Pan American Health Organization, Managua, NI, USA. aldighsy@paho.org.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Aldighieri
authors.affiliation: U.S. Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, MS A32, Atlanta, GA, 30333, USA. lfb9@cdc.gov.
authors.forename: Lorraine C
authors.initials: LC
authors.lastname: Backer
authors.affiliation: U.S. Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, MS A32, Atlanta, GA, 30333, USA. Eha9@cdc.gov.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Azziz-Baumgartner
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks; D005260:Female; D057097:Harmful Algal Bloom; D006801:Humans; D008297:Male; D009527:Nicaragua / Q000453:epidemiology; D017747:Seafood; D057096:Shellfish Poisoning / Q000453:epidemiology* / Q000209:etiology; D055815:Young Adult