80
|
FALL 2011
he hazard of human infection for those exposed
to the sea has been known for a long time, but the
public is becoming more aware of it as new evidence
of the oceans’ rapidly deteriorating health emerges.
Even the most pristine seawaters are inhabited by
large numbers of microbes.
Most of them are harmless to humans, but some, like
the vibrio species, can make people sick or even kill them.
Increased pollution, warming and acidification of the
oceans, all of which cause the death and extinction of fish
and coral species, also promote the growth of indigenous
microbes and increase the concentrations of terrestrial
pathogens. Pollution and microbial hazards are greatest
in coastal waters; unfortunately, this is where most
recreational activities occur.
Routes of infection
Indigenous and introduced microbes may cause illness in humans either by
infection or indirectly by intoxication. The sheer volume of seawater and its
constant movement usually dilute foreign microbes below concentrations
necessary for human infection. But there are many conditions when critical
concentrations may be reached or when the threshold for infection in
an individual is lowered. The greatest risk for human health comes from
consumption of seafood (See “Hazardous Marine Life,” Page 56).
Human potential for contracting diseases from pathogens in the marine
environment depends on exposure time, the virulence of the pathogens
and the susceptibility of the individual. Microbes generally infect humans
through ingestion, inhalation or mucous-membrane exposure (naturally
A t eat to
scu divers?
B y M i c h a e l M i l l e r , P
h
. d . , a n d P e t a r D e n o b l e
Mi robial
Ha ards
In locations where site pollution is present,
cases of gastroenteritis and respiratory illness
may be elevated.
80-85_Bacterial_Hazards_Fall2011.indd 80
9/29/11