The Kwazulu-Natal Department of Health has reported 2,175
cases and 22 deaths since the start of the outbreak in mid-August 2000. The outbreak is in northern Kwazulu-Natal, affecting the Lower Umfolozi Districts which include Ngwelezane and Empangeni and Eshowe/Nkandla areas. The WHO Office in South Africa is working with the Department of Health to implement preventive and control measures, including health education, case management and surveillance and monitoring.
Cholera is an acute intestinal infection caused by the bacterium Vibrio cholerae. It has a short incubation period, from less than one
day to five days, and produces an enterotoxin that causes a copious, painless, watery diarrhea that can quickly lead to severe dehydration and death if treatment is not promptly given. Vomiting also occurs in most patients.
Most persons infected with V. cholerae do not become ill,
although the bacterium is present in their faeces for 7-14 days. When illness does occur, more than 90% of episodes are of mild or moderate severity and are difficult to distinguish clinically from other types of acute diarrhoea. Less than 10% of ill persons develop typical cholera with signs of moderate or severe dehydration.
The vibrio responsible for the seventh pandemic, now in progress, is
known as V. cholerae O1, biotype El Tor. The current seventh pandemic began in 1961 when the vibrio first appeared as a cause of epidemic cholera in Celebes (Sulawesi), Indonesia. The disease then spread rapidly to other countries of eastern Asia and reached Bangladesh in 1963, India in 1964, and the USSR, Iran and Iraq in 1965-1966.
In 1970 cholera invaded West Africa, which had not experienced the
disease for more than 100 years. The disease quickly spread to a number of countries and eventually became endemic in most of the continent. In 1991 cholera struck Latin America, where it had also been absent for more than a century. Within the year it spread to 11 countries, and subsequently throughout the continent.
Until 1992, only V. cholerae serogroup O1 caused epidemic
cholera. Some other serogroups could cause sporadic cases of diarrhoea, but not epidemic cholera. Late that year, however, large outbreaks of cholera began in India and Bangladesh that were caused by a previously unrecognized serogroup of V. cholerae, designated O139, synonym Bengal. Isolation of this vibrio has now been reported from 11 countries in South-East Asia. It is still unclear whether V. cholerae O139 will extend to other regions, and careful epidemiological monitoring of the situation is being maintained.
Cholera is spread by contaminated water and food. Sudden large
outbreaks are usually caused by a contaminated water supply. Only rarely is cholera
transmitted by direct person-to-person contact. In highly endemic areas, it is mainly a
disease of young children, although breastfeeding infants are rarely affected.
Vibrio cholerae is often found in the aquatic environment and is
part of the normal flora of brackish water and estuaries. It is often associated with
algal blooms (plankton), which are influenced by the temperature of the water. Human
beings are also one of the reservoirs of the pathogenic form of Vibrio cholerae.
When cholera occurs in an unprepared community, case-fatality rates may
be as high as 50% -- usually because there are no facilities for treatment, or because
treatment is given too late. In contrast, a well-organized response in a country with a
well established diarrhoeal disease control programme can limit the case-fatality rate to
less than 1%.
Most cases of diarrhoea caused by V. cholerae can be treated
adequately by giving a solution of oral rehydration salts (the WHO/UNICEF standard
sachet). During an epidemic, 80-90% of diarrhoea patients can be treated by oral
rehydration alone, but patients who become severely dehydrated must be given intravenous
In severe cases, an effective antibiotic can reduce the volume and
duration of diarrhoea and the period of vibrio excretion. Tetracycline is the usual
antibiotic of choice, but resistance to it is increasing. Other antibiotics that are
effective when V. cholerae are sensitive to them include cotrimoxazole,
erythromycin, doxycycline, chloramphenicol and furazolidone.
Epidemic Control and Preventive Measures
When cholera appears in a community it is essential to ensure three
things: hygienic disposal of human faeces, an adequate supply of safe drinking water, and
good food hygiene. Effective food hygiene measures include cooking food thoroughly and
eating it while still hot; preventing cooked foods from being contaminated by contact with
raw foods, including water and ice, contaminated surfaces or flies; and avoiding raw
fruits or vegetables unless they are first peeled. Washing hands after defecation, and
particularly before contact with food or drinking water, is equally important.
Routine treatment of a community with antibiotics, or "mass
chemoprophylaxis", has no effect on the spread of cholera, nor does restricting
travel and trade between countries or between different regions of a country. Setting up a
cordon sanitaire at frontiers uses personnel and resources that should be devoted
to effective control measures, and hampers collaboration between institutions and
countries that should unite their efforts to combat cholera.
Limited stocks of two oral cholera vaccines that provide high-level
protection for several months against cholera caused by V. cholerae O1 have
recently become available in a few countries. Both are suitable for use by travellers but
they have not yet been used on a large scale for public health purposes. Use of this
vaccine to prevent or control cholera outbreaks is not recommended because it may give a
false sense of security to vaccinated subjects and to health authorities, who may then
neglect more effective measures.
In 1973 the WHO World Health Assembly deleted from the International
Health Regulations the requirement for presentation of a cholera vaccination certificate.
Today, no country requires proof of cholera vaccination as a condition for entry, and the
International Certificate of Vaccination no longer provides a specific space for recording
Trade in Food Products Coming from Cholera-Infected Regions
The publication "Guidelines for Cholera Control", available
through WHO's Distribution and Sales Unit, states the following:
"Vibrio cholerae 01 can survive on a variety of foodstuffs
for up to five days at ambient temperature and up to 10 days at 5-10 degrees Celsius. The
organism can also survive freezing. Low temperatures, however, limit proliferation of the
organism and thus may prevent the level of contamination from reaching an infective dose.
"The cholera vibrio is sensitive to acidity and drying, and
commercially prepared acidic (ph 4.5 or less) or dried foods are therefore without risk.
Gamma irradiation and temperatures above 70 degrees Celsius also destroy the vibrio and
foods processed by these methods, according to the standards of the Codex Alimentarius,
"The foods that cause greatest concern to importing countries are
seafood and vegetables that may be consumed raw. However, only rare cases of cholera have
occurred as a result of eating food, usually seafood, transported across international
borders by individuals.
"...Indeed, although individual cases and clusters of cases have
been reported, WHO has not documented a significant outbreak of cholera resulting from
commercially imported food."
In summary, although there is a theoretical risk of cholera
transmission with international food trade, the weight of evidence suggests that this risk
is very small and can normally be dealt with by means other than an embargo on
WHO believes that the best way to deal with food imports from
cholera-affected areas is for importing countries to agree, with food exporters, on good
hygienic practices which need to be followed during food handling and processing to
prevent, eliminate or minimize the risk of any potential contamination; and to set up
arrangements to obtain assurance that these measures are adequately carried out.
At present, WHO has no information that food commercially imported from
affected countries has been implicated in outbreaks of cholera in importing countries. The
isolated cases of cholera, that have been related to imported food, have been associated
with food which had been in the possession of individual travellers. Therefore, it may be
concluded that food produced under good manufacturing practices poses only a negligible
risk for cholera transmission. Consequently, WHO believes that food import restrictions,
based on the sole fact that cholera is epidemic or endemic in a country, are not