Enteroaggregative Escherichia coli - Escherichia coli: Pathotypes and Principles of Pathogenesis - page 242

Austria ( Presterl et al., 1999 ), which emphasizes the role of EAEC in developed
countries.
EAEC as a cause of diarrhea in AIDS patients
The role of EAEC as an important pathogen in AIDS patients continues to
develop, and EAEC now ranks among the most important enteric pathogens
in this sub-population ( Wanke et al., 1998a , b ). EAEC was reported as the pre-
dominant cause of diarrhea among HIV-infected patients in the Central African
Republic ( Germani et al., 1998 ). The importance of EAEC in persistent diar-
rhea among African AIDS patients was re-emphasized during a study in Senegal
( Gassame-Sow et al., 2004 ). The finding that HIV replication is enhanced by
inflammation and activation of NF-κB raises the concern that EAEC-induced
inflammation may add to the rapid downward decline of millions of African
AIDS patients ( Klein et al., 2000 ).
EAEC in travelers
As outbreaks suggest, EAEC is capable of causing diarrhea in adults. In a recent
review of all published studies of traveler's diarrhea, EAEC was in aggregate
second only to ETEC as the most common pathogen among patients with trav-
eler's diarrhea ( Shah et al., 2009 ). EAEC was a major cause of diarrhea among
Spanish travelers going to the developing world, with an incidence identical to
that of ETEC ( Gascon et al., 1998 ). Studies in Mexico have shown that in con-
trast with ETEC, in which travelers are most susceptible during the first weeks
of exposure, travelers remain susceptible to EAEC infection throughout their
stay ( Adachi et al., 2002 ), likely reflecting the particular ability of EAEC to
evade the immune system and cause persistent diarrhea ( Okhuysen et al., 2010 ).
Travelers in Mexico showed that the rate of EAEC colonization increased pro-
portionally with the length of the stay ( Adachi et al., 2002 ).
EAEC and malnutrition
Investigators working in Fortaleza, Brazil, have repeatedly implicated EAEC
as the predominant agent of persistent diarrhea ( Wanke et al., 1991 ; Fang et al.,
1995 ), which is associated with growth retardation. Interestingly, in this study
population even asymptomatic patients infected with EAEC exhibit growth
retardation ( Steiner et al., 1998 ) compared with uninfected controls. In longitu-
dinal studies of an infant cohort in Guinea-Bissau, EAEC infection was highly
prevalent and was accompanied by growth retardation, although a direct link
could not be established ( Valentiner-Branth et al., 2001 ). Given the high rate of
asymptomatic excretion of EAEC in much of the developing world ( Fang et al.,
1995 ), understanding its potential role in malnutrition and growth retardation is
a high priority.