UNDER THE MICROSCOPE
It’s summer, and we are going to see outbreaks of food – and water-borne diseases, one of which is cholera. Cholera is an acute gastroenteritis caused by Vibrio cholerae, which causes profuse watery diarrhea. Without adequate fluid replacement, acute and severe dehydration can result in circulatory collapse and death.
The Philippines is no stranger to cholera, having had cholera epidemics/pandemics of which the most significant was in 1902, when there were 166,252 cases reported with 109,461 deaths. The death rate was 65.84 percent, which was due to the lack of intravenous rehydration then.
Even with the availability of intravenous rehydration, an acute influx of cholera cases can overwhelm the health system, causing high mortality rates again (it is less than one percent if treated but rises to 25-50 percent without treatment). We also have to contend with the sad state of clean water availability, since many rural areas and even towns and cities have poor or no access to clean water and sanitation. Breakdown of water infrastructure and non-chlorination also play a role in cholera outbreaks even in urban settings.
Sad to say, cholera has been endemic in the Philippines, where 87 percent of provinces reported cholera cases in a survey from 2008 to 2013. In 2023, the Philippines was one of 30 countries reporting cholera cases worldwide, the only country in the Western Pacific to do so. The data shows a significant increase in cholera cases worldwide from 2022. Thus, the stage is being set for another cholera pandemic, especially in this era with violent conflicts, widespread poverty, population crowding, and mass displacements caused by natural disasters brought about by the effects of climate change.
Early diagnosis is very important, both for treatment and public health purposes. There are rapid diagnostic tests (RDT) for cholera but these tests may suffer from poor sensitivity, since they were developed during epidemics and outbreaks. A negative RDT does not rule out cholera and it should be followed up by polymerase chain reaction (PCR) testing, which is now regarded as the gold standard for the diagnosis of cholera. The rapid set up and deployment of PCR testing laboratories during the Covid-19 pandemic gives us the opportunity to deploy PCR testing in case there are cholera outbreaks. Hopefully, these PCR labs are re-oriented to perform communicable disease testing to monitor for possible outbreaks like cholera, pertussis, measles, polio and other diseases with epidemic potential.
The good news is that oral cholera vaccines (OCV) are now available. There are at least four oral cholera vaccines endorsed by the WHO via its vaccines prequalification program. These can be given to people over the age of two and require two doses that give full protection for up to three years. These OCVs are very safe and have virtually no side effects. There are other OCVs in the pipeline that are equally efficacious and safe.
So far, cholera vaccines are not part of the Expanded Program of Immunization of the DOH. This is due in part to the low existing manufacturing capacity that is exceeded by the global demand for OCV, forecasted to be 1.5 billion doses based on estimates of the Global Alliance for Vaccines and Immunization (GAVI). But we should have OCV stockpiled locally that can be used in response to localized outbreaks like what we sporadically experience even in the present.
Should we be concerned enough to avail of OCV? It all depends on personal circumstances like living in an endemic area, presence of an outbreak, perception of lack of water safety and sanitation, travel to an endemic area, etc. Currently, cholera vaccines are recommended for travel to the Philippines. One can argue that since we live in a cholera-endemic country, we should have cholera vaccination for protection.
Personally, I would prefer to get the OCV, as it offers protection for myself and my family. It is efficacious and very safe, per vaccine trials. If enough people are vaccinated for cholera, it can serve to break the chain of transmission in the community, thus preventing further spread of the disease.
Whether we dine at home or in restaurants, we can never be sure of the cleanliness of food or drinks that we partake of. That was the case of a friend whose 12-year-old son had to be hospitalized due to diarrhea. Eventually, the whole household came down with gastroenteritis.
The cholera vaccine can prevent undue illness and hospitalization in case we ingest cholera-tainted food or drinks. The small investment in oral cholera vaccination can yield huge savings in unforeseen hospital confinements, which can result in a huge medical bill.
Unfortunately, we cannot yet vaccinate for other prevalent food – and water-borne diseases. But I have faith in medical science that we will come up with vaccines for many of the more important diarrheal diseases.
Vaccines save lives.