The WHO has issued a new set of recommendations for the control of cholera. And there, hidden in a forest of clauses of the kind more frequently seen in prenuptial agreements than in health recommendations, the careful reader will find the statement ‘… the use of OCV* in certain endemic situations should be recommended…’. Readers unfamiliar with the protracted battle over the use of vaccines for the control of cholera in endemic situations may read this sentence and miss a sea change.
Cholera has a cachet in the lay world similar to tuberculosis or malaria. After all it is hard to imagine that Gabriel Garcia Marquez would have called his novel ‘love in a time of shigellosis’ or any other enteric disease; (Marquez 1988). There remains a justified horror of cholera outbreaks among people in less fortunate conditions. A cholera outbreak in Europe or the US is hard to imagine but so is a malaria outbreak. The reason why we do not have a world cholera day is probably because of the low mortality associated with cholera – if it is treated appropriately. A disease which can be cured within several days with rehydration and oral antibiotics does not register when we assess the impact in disability-adjusted life years (DALYs). And herein lies a major problem. DALYs were a major breakthrough. Bill Gates reportedly called the World Development Report 1993: Investing in Health (World Bank 1993), which brought the concept of DALYs to a wider public, a terrific read. Yet DALYs fail to capture the significance of a disease like cholera.
Having lived through a single cholera outbreak is probably sufficient to fully understand the chain of catastrophic events: initially, curiosity about the first cases of watery diarrhoea admitted; the nosocomical infection of most or all patients on the ward; the closure of the ward; rigorous but belated disease-control measures; hospitals besieged by patients with watery diarrhoea; excess mortality not so much among the cholera patients but among other patients who cannot access the care they require. These are just the direct consequences. Family members have to look after their sick, shops and banks stay closed and the normal functions of a community come to a halt. At which stage the media catch on to the news and draw attention to the catastrophe affecting the community. In due time the government points out the damage caused by these unsubstantiated reports, and where an opposition exists the blame game can begin.
This constitutes another unusual aspect of cholera. Not only can the damage not be assessed in DALYs, cholera remains a highly political issue. No matter where we met with affected communities, invariably the government was considered at least partially responsible and consequently highly sensitive. For example: Thailand does not report cholera cases. Public health experts are aware that ‘acute watery diarrhoea’ cases in Thailand are likely to be thinly disguised cholera cases. But before we single out Thailand, the fact that no cholera case has been reported from the People's Republic of China has less to do with the absence of cholera than with the complete clampdown on reporting of cholera cases. Younger public health professionals early in their training become aware of the individual stigma associated with AIDS. Communities reporting cholera outbreaks are well aware of the stigma associated with cholera outbreaks.
Besides the intangible damage cause by a tarnished reputation (who wants to live in a city thought to be cholera-ridden?) other negative effects should be measurable. The two economic sectors principally affected are seafood exports and tourism. While it is possible that Vibrio are inadvertently allowed to contaminate the water surrounding seafood during packaging, there is no evidence that Vibrio infect shrimp or fish. Yet the export market of small nations can collapse after reports of a cholera outbreak. Similarly, most tourists have no chance of experiencing a cholera episode as long as they follow the most basic rules of hygiene (only drink bottled or boiled water, only eat well-cooked food and fruit you have peeled yourself). It may therefore not come as a surprise that the countries currently reporting cholera outbreaks derive a larger income from humanitarian aid than from seafood exports and tourism: 94% of the 101 383 cholera cases and 99% of the 2345 related deaths registered with the WHO in 2004 occurred in sub-Saharan Africa (Sack et al. 2006).
So what is a government official in charge of preventing the next cholera outbreak in her country supposed to do? If in doubt, turn to WHO for technical advice. This is reason why the new WHO recommendations are important. Many developing countries have a cadre of local experts to advise them on the prevention of malaria, tuberculosis and HIV infections. Expertise on cholera prevention is much harder to come by. The absence of independent experts and the political climate after a cholera outbreak (Why didn't you follow WHO recommendations?) give WHO recommendations on cholera prevention unusual weight. So what did WHO recommend up to now?
There have been no controlled trials but experience and common sense suggest that improvements resulting in safe water supply and sanitation will prevent cholera and not only cholera but also a long list of other enteric infections. Nobody in his right mind would argue that safe water and sanitation are not a good thing. Why therefore distract from such an important public health good by diverting scarce resources to dubious efforts such as vaccines? Vaccines provide only temporary protection and protect against a single disease, while the benefits of safe water and sanitation are long-lasting and infinitely broader – as has been the argument of the safe water and sanitation lobby for several decades. The sense of this argument has guided WHO recommendations over this period.
Attempts by advocates for vaccination programmes to influence recommendations would be routinely cold-shouldered. Until one memorable day a delegate from an African country with annual cholera outbreaks stood up and asked a perplexed audience mostly determined to ignore alternatives to safe water supply and sanitation: ‘What am I going to tell my people when the next cholera outbreak happens?’ Government decision-makers in charge of preventing cholera outbreaks rarely if ever can influence spending on infrastructure, but they can organize funding and implementation of vaccination campaigns. Furthermore, safe, highly protective oral cholera vaccines have replaced the old injectable cholera vaccine with its justifiedly poor reputation. Currently, one internationally licensed oral cholera vaccine can be used for preventive vaccination campaigns (Hill et al. 2006). This vaccine has been deployed in a mass vaccination campaign in a cholera-endemic area of Mozambique and proved in principle that mass cholera vaccine campaigns are feasible, safe and protective (Lucas et al. 2005).
Receipt of one or more doses of OCV was associated with 78 percent protection (95 percent confidence interval, 39 to 92 percent) and assuming a similar performance as OCVs have shown in studies in Asia 50% or more protection can be expected for at least 3 years (Thiem et al. 2006).
Vaccine campaigns in Darfur, Sudan and Aceh, Indonesia have proven that cholera vaccination campaigns are feasible in complex emergencies. Technology to produce oral cholera vaccine is being transferred to India, which should ensure a cheap supply of large amounts of oral cholera vaccine, and the evaluation a new, cheap, single-dose oral cholera vaccine is underway (Qadri et al. 2005).
Don't be fooled by the clauses and complex wording of the new WHO cholera guidelines. The period during which vaccination programmes for the control of cholera could be safely ignored is coming to an end. While the current recommendations still provide government decision-makers with excuses for why they decided against mass vaccination campaigns, those who do want to raise funds for and implement vaccination campaigns can now refer to WHO when arguing for the use of vaccinations to prevent the next cholera outbreak.