The global cholera pandemic

Nevondo TS and Cloete TE

Dept. Microbiology and Plant Pathology, University of Pretoria, Pretoria, SA
Tel. (2712) 420 3265 Fax (2712) 420 3266

History of the disease

Throughout history, populations all over the world have sporadically been affected by devastating outbreaks of cholera. Recorded evidence of cholera epidemics goes back to 1563 in a medical report from India. In the nineteenth century cholera spread from its apparent ancestral site in the Orient to other parts of the world, producing pandemics in Europe. The first pandemic was recorded in 1817, and we are now well into the seventh cholera pandemic, which started in Indonesia in 1961 and spread rapidly in Asia, Europe, and Africa, and reached South America in 1991. The disease spread rapidly in Latin America, causing nearly 400000 reported cases and over 4000 deaths in 16 countries of the Americas that year. Still the seventh pandemic has not receded; on the contrary, cholera has now become endemic in many parts of the world. According to the Pan American Health Organisation (PAHO), a total of 1076372 cases and 10 098 deaths were reported in the region of the Americas by June 1995. In 1999, a total of 254310 cases and 9175 deaths were officially notified to WHO. However, poor surveillance and fear of international stigmatisation and sanctions lead to underreporting of official numbers by affected countries. Estimates indicate numbers closer to 120000 deaths and many more cases per year. This increasing spread of cholera in recent years may reflect a lack of international quarantine enforcement by some countries which also have primitive public water supplies and inadequate sanitary regulations, the international mobility of carriers in the world's population, and the quick transport of contaminated food and water by ships and aircraft.

The disease

Cholera is an infection caused by the bacteria Vibrio cholerae. People become infected by drinking water or eating food contaminated by the bacteria, poor sanitation as well as personal and domestic hygiene practices. The bacteria present in faeces of an infected person are the main source of contamination and the principal site affected is the gastrointestinal tract. Symptoms include acute watery diarrhoea (sudden diarrhoea with profuse, watery stools), vomiting, suppression of urine, rapid (severe) dehydration, fall of blood pressure, cramps in legs and abdomen, subnormal temperature, and complete collapse. Death may occur within 24 hours of onset unless prompt medical treatment is given to the patient. 

Healthy carriers of V. Cholerae may vary from 1.9 to 9.0%. These symptomless carriers excrete vibrios intermittently with the duration of pathogen discharge being relatively short, averaging 6 to 15 days with a maximum period between 30 to 40 days. Chronic convalescent carriers have been observed to shed vibrios intermittently for periods of 4 to 15 months. Survival of vibrios in the aquatic environment relates sharply to various chemical, biological and physical characteristics of a given stream or estuarine water. The viability of V. cholerae in surface waters has been observed to vary from 1h to 13 days. Although cholera vibrios may persist for only a short time in grossly polluted aquatic environment, faecal contamination from victims of epidemics and the carriers may continue to reinforce their population in water. 

A survey of the cholera epidemic in South Africa 

The current cholera epidemic has gripped rural parts of Northern and Southern KwaZulu Natal since August 2000 in what has developed into the most serious epidemic yet experienced in South Africa. With the movement of people from province to province and between southern African countries, the cholera bacterium has now spread to seven of the nine provinces in South Africa. The Department of Water Affairs and Forestry's Community Water Supply and Sanitation Services section has developed a strategy to monitor the cholera outbreak and track the emergency water supply and sanitation intervention that each province is implementing to curb the spread of the disease. 

As of the 27th July 2001, the total number of cases is 106 224 and the total number of fatalities 228. This is a serious situation considering the size of the South African population, which is approximately 40 million. 

See below for the current total number of cholera cases and fatalities per province:

  East Cape Free State Gauteng Kwazulu  Natal Mpum-
North West  Northern Cape Northern Province Western Cape
Total Cases Reported 1 1 63 105247 111 6 0 794 1
Number of fatalities 0 0 4 218 4 0 0 2 0
Last report Date in 2001 2/3 11/1 10/5 27/7 10/4 15/3 27/2 4/5 7/5

KwaZulu Natal, Northern Province, Mpumalanga and Gauteng are the four provinces where the problem of cholera is most severe. The KwaZulu Natal Province has the majority of cases (99% of the total number of cases reported nationally) and the highest number of fatalities (96% of the total number of fatalities reported nationally). 

Statistics suggest that despite the interventions that the government and other stakeholders are implementing, the cholera situation in the province is getting worse. 

Populations at risk

Cholera occurs in epidemic form when there is rapid urbanisation without adequate sanitation and access to clean drinking water. Hence, the focus of epidemics/pandemics has shifted to developing countries over the last century. Other risk factors include poor hygiene, overcrowded living conditions and lack of safe food preparation and handling. Unstable political and environmental conditions such as wars, famines and floods that lead to displaced populations and the breakdown of infrastructure are very important risk factors as far as the cholera disease is concerned. 

Economic and social impact

It is important to highlight that people often underestimate the socio-economic impacts of water and sanitation related diseases and this is one of the root causes of the deplorable state of many water supply and sanitation initiatives. 

Cholera, like other water related diseases, can cost governments billions of rands to eradicate. Absenteeism by the workforce caused by cholera adversely affects industrial output. Cholera outbreaks can adversely affect tourism and affect tax revenues (productivity losses for business and individual due to the illness decrease tax revenues).
Cholera outbreaks may lead to loss of trade.

Cholera prevention

People living in high-risk areas can protect themselves by following a few simple rules of good hygiene and safe food preparation. The safe disposal of human excreta is of the utmost importance in control of infectious and other communicable disease. Because of the importance of the safe disposal of human excreta, the building of appropriate sanitation systems often is considered synonymous with improving sanitation. However, experience has shown that this is not necessarily the case; and that unless there is an effective primary health care education programme, the installation of improved sanitation facilities alone may not result in improved health.

As with sanitation, water supply must be seen as a complex system of interrelated factors. The successful water supply system is therefore to be found in the successful organisation of the factors affecting the health and social organisation of the community. The provision of an adequate supply of potable water must just be seen as a part of this system. Studies seem to suggest that improvement of water quality alone would have little effect on water handling practices and the subsequent contamination of other stored water. Domestic activities related to the storage and use of water may have a more important bearing on faecal-oral disease transmission. The mere material improvement of water supplies would doubtless prove to be less effective than if people were advised by means of health education of the sources of their disease problems and how to avoid them. Primary health care education is a vital component in prevention of cholera.

Treatment of Cholera

The most important treatment is rehydration, which consists of prompt replacement of the water and salts lost through severe diarrhea and vomiting Early rehydration can save the lives of nearly all cholera patients. Most can be rehydrated quickly and easily by drinking large quantities of a solution of oral rehydration salts. In individual cases of severe cholera, an effective antibiotic can help shorten illness, though rehydration remains the mainstay of treatment.

          Adequate water supply and sanitation are basic requirements for life. Access to clean water and improved sanitation facilities is a fundamental human right. Yet, in many developed and developing countries, water source quality shows continued deterioration and in many cases depleted. These effects are a function of increasing population pressure, agricultural misuse and the inability to keep pace with the increasing demands on the resource. Reported numbers underestimate incidence of water supply and sanitation related diseases, particularly the low endemic diseases that are widespread in both developing and developed countries. A better understanding of the socio-economic, environmental and public health consequences of water supply and sanitation related diseases obtainable through better monitoring surveillance systems, may help the public and policy makers understand the value of microbiologically safe water as well as improved sanitation facilities. In developing countries where resources may be inadequate, particularly in rural communities, basic hygiene education and sanitation programs can be used to improve human health. 

Critical needs for future microbiological safety of water include more realistic valuation of water. This requires better education on the value and limitations of the resources for both public and policy makers. The burden of water supply and sanitation related disease is constantly underreported and the surveillance systems are inadequate, thus intervention studies and aggressive surveillance systems are necessary to provide a clearer understanding of disease burden from contaminated water. There is a need for a better understanding of increasingly susceptible populations in transmission of such diseases. Microbiologically safe water cannot be assumed, even in developed countries. The situation will worsen unless measures are immediately taken. The need for safe drinking water as well as adequate sanitation is a need that binds all of humanity into a single, global community.