After reading your article (Sep.24) on fears about a cholera outbreak in Cambodia
some comments ought to be clarified. Until 1984 one thought that the cholera bacteria
only produced one toxin (CT). Much research in several countries was done to produce
an oral cholera vaccine, but tests on healthy volunteers gave rather varying results.
Prof. Sanyal at Benaras Hindu University found this probably was due to the new toxin
(NCT) which, in contrast to CT, was resistant to heating. Even before this discovery
there were problems in East Africa caused by the indiscriminate use of tetracycline
in an epidemic in Tanzania in 1977.
During the first six months, 1,788 kg pure substance was consumed and, already after
five months, 76 percent of cholera isolates were resistant. This has spread to neighboring
countries, and more expensive drugs are now needed.
In an outbreak of cholera at a Pediatric Hospital in Thailand, Dr. Echeverria and
co-workers (AFRIMS, Bangkok/San Francisco) found that the strain was resistant to
eight antibiotics, including tetracycline.
The latest-found cholera strain (0139) is now studied at many laboratories. The danger
in this case is that it seemingly is invasive or at least destroys the intestinal
cells and at the same time produces the toxin-/s which cause watery diarrhea. It
is, therefore, recommended that stool samples on suspected cholera cases are sent
to research laboratories in India or Thailand.
To build up a diagnostic laboratory in Cambodia takes time and is expensive. Until
diagnostic facilities are ready here, there are many research laboratories in Asia
and elsewhere that will provide such service for the cause of research. With good
transport, stool samples can be sent for analysis.
As to the question of vaccination, most countries have abandoned this due to the
unreliable results. The most efficient per oral vaccines are expensive, and in small
children the protection lasts only about six months.
It should be pointed out that in the treatment of diarrhea diseases, caused by bacteria-producing
enterotoxins, intravenous rehydration should not be used, unless ORS cannot be given.
The injections have to be supervised by health workers, which is expensive and time
consuming, while spoon or sond feeding with ORS can continuously be supervised by
a family member. ORS is also much cheaper.
My own experience from refugee camps in the Sudan also indicated that neonates given
intravenous rehydration solution and/or nutrients very rapidly develop atrophy of
When they had recovered from the diarrhea disease, the mortality rate was high due
to severe malnutrition caused by malabsorption.
- Stig Larsson, MD, VMD, PhD