Elevated levels of immunoglobulin A to Giardia lamblia during a waterborne outbreak of gastroenteritis.
During an outbreak of diarrheal illness among residents of a trailer park in rural Vermont, 37 (30%) of 122 residents met the case definition of outbreak-related giardiasis. Convalescent-phase sera from 24 residents and 20 nonresident control subjects were tested by enzyme-linked immunosorbent assay for immunoglobulin G (IgG), IgM, and IgA antibodies to Giardia lamblia. Residents showed higher levels of parasite-specific antibody than did nonresident controls for IgG and IgA but not IgM. Nine residents with giardiasis had a higher median level of G. lamblia-specific IgA but not IgG or IgM than 15 healthy residents (0.61 versus 0.16 optical density units; P = 0.004). Moreover, parasite-specific IgA levels were higher in those consuming tap water than in those who did not (0.31 versus 0.08 optical density units; P = 0.03) and increased with increasing water consumption. Levels of serum antibody to G. lamblia, particularly IgA, may be useful in determining exposure to G. lamblia-contaminated water and illness from G. lamblia during waterborne outbreaks of diarrheal illness.
Epidemiology Division, Vermont Department of Health, Burlington 05402.
G
G
Birkhead
E N
EN
Janoff
R L
RL
Vogt
P D
PD
Smith
D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis; D004196:Disease Outbreaks; D005260:Female; D005759:Gastroenteritis / Q000453:epidemiology / Q000276:immunology; D005872:Giardia / Q000276:immunology*; D005873:Giardiasis / Q000453:epidemiology / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis*; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007411:Intestinal Diseases, Parasitic / Q000453:epidemiology / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012424:Rural Population; D014707:Vermont; D014881:Water Supply
D000913:Antibodies, Protozoan; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M