222
Stout
et al
. (1986), observed that the rise in the temperature in order to
eliminate
Legionella
from pipes requires the water heated at 70 °C and flowing
through the interior of the pipe per 30 minutes. On the other hand, the AWT
(2003) recommends that the temperature of water should be above 60 °C
(preferably above 66 °C) and maintained in circulation for a period superior to
30 minutes. On their turn, Muraca
et al
. (1987) show in their work that water in
the range between 50 and 60 °C can reduce 7 log cycles from the interior of the
pipes in a time interval inferior to 3 hours. Sabria and Yu (2002) and the World
HealthOrganization (WHO, 2002) state that the thermal processmust be thefirst
measure to be adopted in case of detection of an outbreak caused by
Legionella
.
A similar recommendation, with relation to the time-temperature binomial
presented byWHO, is also given by Chen
et al
. (2005) who state that the rinsing
with hot water must be the first choice as a disinfection method for
Legionella
when an outbreak caused by this microorganism occur in a hospital, specially
because the thermal disinfectiondoes not require special equipment tobe applied
and can be promptly conducted.
Chen
et al
. (2005), Sabria and Yu (2002) and Lin
et al
. (1998) indicate as
an advantage of the thermal process, the fact that it requires no acquisition of
specific devices, which reduces the initial investment, and that there is no need
of specialized personnel to conduct this disinfection process. However, the main
disadvantage is that it requires longer time of operation, which increases the costs,
both from an economic and a personnel point of view, in case of hospitals with
manybeds.Thus, the authors recommend that oncefinalized the shock treatment
of the pipes with hot water, another form of disinfection should be employed,
such as copper/silver ionization.
Despite of the many advantages presented by the thermal treatment for
the control of
Legionella
, some inconveniences, besides of the cost that can be
