Within the HEAS, a serious discussion has ensued regarding the current and future status of cholera in Haiti, which began with a question from an outside agency:
- [From a major NGO seeking to implement major prevention efforts in Haiti] We know these predictions can be somewhat uncertain, but we would be grateful to hear your opinion as a medical actor on the ground. Your first-hand knowledge about the infection patterns and the current pace of health and water sanitation interventions makes you well poised to help us see a few years ahead into the cholera epidemic.
- [From me to HEAS partners internationally recognized as cholera experts] Guys, I could use your input and advice regarding the [above question] and would like to form a consensus opinion, if possible.
- The usual cholera epidemic attack rate (AR) among immunological susceptible populations is 2%. This estimated attack rate considers only severe and some moderate cholera cases requiring hospitalization. Most of the total cases (95%) are mild or asymptomatic and may not be detected by the surveillance system
- [My reply] Is this AR what you guys observed in Peru in '91? Reason why I'm asking is we are dealing with a totally naive environment (albeit we are in a time period subsequent to first introduction [i.e. first wave]).
- Yes, this is what it was observed in the 1919 Latin America epidemic as well as previous descriptions of cholera epidemics in Asia and Africa. I think that once cholera is established in the environment , all population is affected sooner or later if the water and sanitation conditions are not adequate. That is the case of Southeast Asia, over there the only susceptible population is small children with no antibodies against cholera.
- [My reply] This is a very important observation- we are still seeing a high percentage of adults affected versus kids- at least in the case of Pestel if I'm not mistaken. So, the situation may be endemic in Port au Prince but still epidemic in the rural areas?
- There may be a few pockets of susceptible populations. Nevertheless, after cholera strikes, we have to be very careful with the diagnosis. During the last waves of the 1991epidemic, I went to investigate diarrheal diseases outbreaks that were wrongly diagnosed as cholera. Many of these outbreaks were disenteric amebiasis, E coli, salmonella, cryptosporidium, etc. It is time to start to invest some resources in confirming the outbreak agents.
- [My response] Right, copy. That seems to have been the problem with the Pestel situation [i.e. public health officials delaying 72 hrs to respond because the situation in Pestel was not laboratory-confirmed cholera]- a bias that it was not due to cholera until lab confirmation proves otherwise. If we had not intervened, people would have needlessly died.
- I just checked the number of cases accumulated in Haiti until January 2012:
The Ministry of Health has reported 524,861 cumulative cholera cases, 282,989 hospitalizations and 7,018 deaths, as of 8th january 2012. The overall fatality rate is 1.3 percent nationwide. The general trend is towards a decrease in the number of new cases and fatality
*Source: Last report of MSPP as of 8 january 2012
If we have a total population of 10 million inhabitants it looks like the 282,989 hospitalized cases (~2.8%) shows that the population is exhausted and the cholera epidemic may have entered into a endemic patter of transmission. If somebody comes to deliver the vaccine or establishes any control strategy it will look as a very effective intervention, just by being temporally associated with the development of immunity among the population.
- [My response] What if these numbers are an underestimate given the 2/3 rural mountainous / unreached / poorly reported areas of Haiti? Are we able to consider this? Thank you for the discourse.
- I agree. Indeed, there must be an underestimation of the number of cases. The 2% attack rate is based on similar or even less sensitive surveillance systems. If the number of cholera cases is greater, again , this means that most of the Haitian population is immune. The sadness of this history is that we did not concentrated all our efforts in saving the lives. To achieve this level of natural immunity with more than 7,000 deaths is a failure. At this point water interventions will be strongly associated with no cholera cases, latrines will be strongly associated with no cholera cases, voodoo bone powders will be strongly associated with no cholera cases. The colloquium of this disaster is the return of UN "experts" to say that their presence has been the key factor in stopping the epidemic.