Molecular analysis of household transmission of Giardia lamblia in a region of high endemicity in Peru.
BACKGROUND
Giardia lamblia is ubiquitous in multiple communities of nonindustrialized nations. Genotypes A1, A2, and B (Nash groups 1, 2, and 3, respectively) are found in humans, whereas genotypes C and D are typically found in dogs. However, genotypes A and B have occasionally been identified in dogs.


METHODS
Fecal Giardia isolates from 22 families and their dogs, living in Pampas de San Juan, were collected over 7 weeks in 2002 and 6 weeks in 2003. Samples were genotyped, followed by sequencing and haplotyping of many of these isolates by using loci on chromosomes 3 and 5.


RESULTS
Human infections were all caused by isolates of genotypes A2 and B. Human coinfections with genotypes A2 and B were common, and the reassortment pattern of different subtypes of A2 isolates supports prior observations that suggested recombination among genotype A2 isolates. All dogs had genotypes C and/or D, with one exception of a dog with a mixed B/D genotype infection.


CONCLUSIONS
In a region of high endemicity where infected dogs and humans constantly commingle, different genotypes of Giardia are almost always found in dogs and humans, suggesting that zoonotic transmission is very uncommon.
Department of Veterinary Science and Microbiology, University of Arizona, Tucson, USA.
Margarethe A
MA
Cooper
Charles R
CR
Sterling
Robert H
RH
Gilman
Vitaliano
V
Cama
Ynes
Y
Ortega
Rodney D
RD
Adam
D000818:Animals; D017931:DNA Primers; D004283:Dog Diseases / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission; D004285:Dogs; D019353:Endemic Diseases; D005243:Feces / Q000469:parasitology; D015698:Genomic Library; D005838:Genotype; D016829:Giardia lamblia / Q000145:classification / Q000235:genetics*; D005873:Giardiasis / Q000453:epidemiology / Q000235:genetics* / Q000635:transmission*; D006801:Humans; D010568:Peru / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D015047:Zoonoses / Q000469:parasitology / Q000635:transmission
D017931:DNA Primers