Development and Health
"Has the World Health Organisation’s Diarrhoeal Diseases Control Programme been effective, specifically in controlling cholera?"
Brendan S. Howard
The World Health Organisation (WHO) - the UN specialist agency for health - together with UNICEF, UNDP, and the World Bank launched the Diarrhoeal Diseases Control Programme (CDD Programme) in 1980. The prime objective of the Programme was to significantly reduce child mortality rates across the globe. This seemed justified: at least 5 million children died of diarrhoeal diseases in 1980 from well over 500 million cases. The WHO Director General Dr. Halfden Mahler aimed for a programme that would be:
"…training health workers at different levels; (and) to accord high priority to research activities for the further development of simple, effective and inexpensive methods of treatment, prevention and control…"
Cholera has undoubtedly been one of the greatest challenges facing the CDD Programme and will be looked at in greatest detail in this essay. However, it is not the deadliest diarrhoeal disease, with Shigella causing approximately 33 times as many deaths annually. 80% of diarrhoeal dieseases are bacterial and the other 20% amoebic (causing a type of gastoenteritis from the Entamoeba histolytica, which infects the bowel). Mass ORT implementation pre-dates the CDD Programme by nine years – ORT being the most significant combattant method against diarrhoeal diseases today. However, the CDD Programme provided $332 million for ORT during 1985-93 and their research covers infant and child feeding, vaccines, water supply, sanitation and hygiene among other things. This essay looks at how effective various CDD Programme methods have been in controlling cholera with specific reference to case studies in Orissa and Kolkata (formerly Calcutta) in India, and in Bangladesh.
Fig. 1 shows how equatorial regions, particularly East-Africa have seen recurring and even worsening incidence of cholera in recent years. On the other hand, some areas such as Indonesia, NW Africa, and Sudan have had no cases of cholera. The map also shows there has been little change with continuing low numbers of cases (mostly imported) in westernised countries and steady yet more numerous levels in countries such as India, Brazil, and Argentina. Some countries, although not eradicating the disease, have had notable drops in incidence levels, most notably Peru with a decrease from 322,562 cases in 1991 to 41,717 cases in 1998.
With many cholera pandemics the spread of cholera follows the routes of travellers and merchants. The CDD Programme devised International Sanitary Regulations (later renamed International Health Regulations – IHR) and these were adopted by the 22nd WHA on 25 July 1969. This was however, only a step in the path to eradicating cholera. It was also recognised that cholera vaccinations had not helped to control cholera and so in 1973 the WHA amended the IHR so that cholera vaccination should no longer be required of any traveller.
In 2004 UNICEF published a list of the top 10 countries "that have failed to make a dent in child mortality." These were Cambodia, Iraq, Botswana, Zimbabwe, Swaziland, Kenya, Cameroon, Ivory Coast, Kazakhstan and Uzbekistan. Of these 10 counties, 7 have recently reported cases of cholera including Kenya which reported 4,957 cases from 1 January to 19 March 1999 and Cameroon which reported 2,924 cases from 1 January to 15 June 2004. In the following graph you can see how six of the ten countries have had a significant number of cholera cases since 1997:
Despite this, the total number of cholera cases reported has fallen in recent years. However, the overall case-fatality rate has remained stable at 3.6%.
Recent cholera epidemics have been of the Vibrio cholerae O1 serogroup El Tor bacterium (distinguised from classic biotypes by the production of hemolysins), the cause of, and prevelent bacterium of the seventh (and current) cholera pandemic which broke out in 1961. The O1 biotype is treatable with high success rate (see below) and undernutrition has been found to have no effect on risk of colonising the bacterium. However, undernutrition is the result of poverty and goes hand in hand with poor sanitation and overcrowding, some of the greatest problems facing the CDD Programme in preventing the spread of diarrhoeal disease – undeniable factors in the cause of epidemics. Only in Bangladesh has a classic biotype (serogroup O139) re-emerged (in 1982) to produce a more severe strain of cholera, although it tended to affect older populations most.
The Vibrio cholerae bacterium produces enterotoxins which are the direct cause of diarrhoea and vomiting and it is such symptoms that cause fatalities. Fig. 4 on the following page shows the pathophysiology of cholera including diarrhoea and vomiting.
If a patient is not treated, mortality rates can be as high as 50-60%, more than 10 times greater than those who are treated. With some victims not receiving any treatment the current CDD policy concentrates on providing basic ORS as soon as symptoms develop. ORS is cheap to provide and its active ingredients are sodium and glucose. In 2002 a new, more effective ORS formula was introduced following CDD research and resulted in reduced severity of diarrhoea and vomiting, reduction in the period of illness, the number of hospitalisations, and the need for costly intravenous (IV) treatment. Since ORS was introduced in 1978 the annual number of child deaths from acute diarrhoea has reduced from 5 million to 1.3 million. This statistic should be significantly accurate as the WHO is a widely respected international body and cholera strains can be identified easily in the laboratory. However, many victims will not have had tests done. It would not be in the interests of the WHO to lie about statistics as overestimates of deaths would damage their reputation and underestimates could harm their funding.
CDD research is concentrated on infant and child feeding (identifying infant feeding practices and their relationship with diarrhoeal illness and death), vaccines, water supply, sanitation and hygiene. CDD studies also found that exclusively breastfed infants have less incidence of diarrhoea and another source even indicates breastfeeding is protective against cholera - this source has limited credibility however, with its "sole business" the publicising of its website rather than conducting its own independent research. It is simply a publicist of studies from credible external sources. Tetra cycline (an antimicrobial) is also used but there have been reports of its misuse in Kenya (see map below).
Tetracycline is readily available in Kenya but Vibrio cholerae was found to be resistant to the drug and it was not effective in rehydrating the patients. However, tetracycline can be affective against Vibrio cholerae, as was found in Kolkata in 2001. The CDD has recently published "The Rational Use of Drugs in the Management of Acute Diarrhoea in Children" which does not outlaw the use of tetracycline and similar drugs but includes "specific guidance on when to use [them]".
Research recently published by the NAS has found this is because the El Tor bacterium multiplies when the number of bacteriophages die (the phages live off the bacterium) from drowning. This is why cholera is known as a water-borne disease. The BBC also covered the breakthrough and commented that in the weeks and months following the Asian Tsunami of 26 December 2004 there was a serious scare over potential cholera epidemics.
"The most important strategies are to attempt to prevent cholera transmission by providing emergency clean water supplies, and a disease surveillance system." - Dr Paul Shears, Liverpool School of Tropic Medicine.
In the 1980s the CDD Programme commissioned the London School of Hygiene and Tropical Medicine to "conduct in-depth reviews of the potential effectiveness, feasibility and cost of 18 interventions to prevent diarrhoea." The most favourable actions included improvements in water supply, sanitation and hygiene behaviours, and development of rotavirus and cholera vaccines, but there was no mention of emergency clean water supplies. Another study was done in the 1990s with similar findings and the WHO reported "The conclusions of these reviews significantly influenced future CDD and ARI Programme activites." With funding limited and the extent of conditions across the globe suitable for cholera epidemics the CDD Programme has not been able to tackle every problem and the sheer scale of world poverty means preventitive measures everywhere are unfeasable.
Sewage fisheries provide 10-20% of the fish consumed in Kolkata (see map at bottom of page) and the vibrio parahaemolyticus bacterium (the second most common cause of cholera) have been found in the intestines of the fish from the sewage fed ponds. No epidemiological studies have been carried out by the CDD Programme to assess the risk attributable to the use of sewage in the aquaculture ponds and little microbiological data is available. In another Kolkata cholera epidemic between 4th and 18th April 2000 it was found that furazolidone – the drug previously recommended for treating children - was resistant to the strains of Vibrio cholerae O1. Findings such as this will improve future treatment for patients but question the extent of research previously done for the CDD Programme.
The progress of the CDD Programme in combatting cholera is undermined by the fact there were 137,071 cases of cholera in 2000 and only 42,614 in 1980. However, the variance in the number of cases annually is huge with 294,094 cases in 1998 – the worst ever year for cholera case numbers and also a slightly higher CFR at 6%. Other than 1997/98 (largely due to a huge pandemic of cholera across tropical East-Africa) there has been a steady decrease in the global CFR since 1984 for which the CDD Programme should be commended. This is shown by the graph on the following page.
WHO stated in 1998: "Countries with strong CDD programmes, trained health workers and health facilities supplied with essential drugs and equipment have been able to maintain case fatality rates below 1%." However, although WHO are an independent body the CDD Programme is a WHO programme and therefore WHO are likely to be selective in what they say and be more inclined to promote the more successful aspects of their programmes. On the other hand, countries such as Sudan have developed CDD Programmes and cholera has been eradicated.
It is clear that the CDD Programme has helped control the spread of cholera. However, the number of cases has remained steady and some regions have seen new epidemics of cholera – particularly equatorial East-Africa. The CDD Programme is well funded but the task of controlling cholera is epic. The CDD Programme has done well to combat specific outbreaks of cholera such as the South African epidemic in August 2000 which had the lowest CFR ever documented (<0.5%) for an epidemic of its magnitude.
The CDD Programme must continue to improve health care around the world and educate people about the dangers of cholera and the diarrhoeal diseases. Areas most as risk such as equatorial East-Africa must be given much greater support with health policies such as PHC implemented so when future epidemics occur they can be better controlled.
Fig. 1. Levels of Cholera in 1998 in Comparison with 1991 (template only), Houghton Milfflin Company – statistics from WHO.
Fig. 2. Cholera Epidemics Since 1997, n/a – statistics from WHO.
Fig. 3. Bangladesh, Nationmaster.com.
Fig. 4. Pathophysiology of Cholera, The University of Texas Medical Branch.
Fig. 5. Kenya, Familia Matioli.
Fig. 6. Orissa, Nationmaster.com.
Fig. 7. Aerial View of Sewage Fisheries in Kolkata, SANDEC.
Fig. 8. Kolkata, Changemakers.net.
Fig. 9. Cholera, reported number of cases and case fatality rates, per continent, The World Health Organisation.
Fig. 10. South Africa, Elephant Coast.
Child Mortality Rising
Fast in Parts of Asia-U.N.
Cholera in Cameroon
Cholera Understanding "Improved"
Dialogue on Diarrhoea Online: Issue no. 52: March-May 1993
Disease outbreaks reported
Explosive Outbreak of El Tor Cholera Amongst Migrant Labourers of a Brick Field Near Calcutta
Health Status of Primitive Tribes of Orissa
Global Rehydration Therapy
Immunization Rates of India
Most Deadly Infections
Oral Rehydration Salts (ORS)
Reemergence of Epidemic Vibrio Cholerae O139, Bangladesh
Section II: Study the Retail System and Choose a Target Audience
The Evolution Of Diarrhoeal And Acute Respiratory Disease Control At WHO http://www.who.int/child-adolescent-health/New_Publications/CHILD_HEALTH/WHO_CHS_CAH_99.12.pdf (12/12/04)
Vibrio Cholerae and Asiatic Cholera
Wastewater Use in Aquaculture
Weekly Epidemiological Record
WHO Report on Global Surveillance of Epidemic-prone Infectious Diseases