Cholera vaccines are considered not commercially viable, with pharmaceutical companies avoiding its production since it does not earn them high returns.
This has attributed to persistent shortage of the vaccines, yet there is an upsurge of cholera in several African countries already suffering from high poverty levels and broken down health systems.
Medecins Sans Frontiers (MSF) – Doctors without Borders, an international, independent medical humanitarian organization has moved swiftly to provide medical assistance to people affected by such epidemics, conflicts, disasters, or exclusion from healthcare.
Dr. Nitya Udayraj, the MSF Medical Coordinator in Kenya told an online Science Media Café organized by the Media for Environment, Science, Health & Agriculture (MESHA) organisation that climate change seems to have triggered the sudden upsurge of cholera in the affected areas.
However, Udayraj reassured the public that the availability of two doses of Shanchol and Euvichol (vaccines) provides protection against cholera for three years, while a single dose provides short term protection against cholera (Vibrio cholera infection).
The World Health Organization (WHO) stated that the two vaccines (Shanchol and Euvichol) are the vaccines currently available for mass vaccination campaigns through the Global OCV stockpile, which is supported by Gavi, the Vaccine Alliance.
Udayraj warned that Cholera knows no borders and as such cautioned the neighboring African countries not to drop their guard but instead build up their surveillance in order to curb further spread of the epidemic not only on the continent but globally.
“This disease thrives under poor sanitation and the use of dirty water for drinking. It causes dehydration which is the main cause of morbidity (deaths) and so the need to move swiftly and supply the much needed oral application (medication),” she explained.
On reports that there were fears that some strain of cholera could be resistant to the two drugs, the medic said antibiotic resistance is a global problem not just for cholera but also for other diseases.
Among the drugs used for treatment of cholera are; Norfloxacin, trimethoprim-sulfamethoxazole (TMP-SMX), and ciprofloxacin which are effective, but doxycycline offers advantages related to ease of administration and comparable or superior effectiveness.
Recently, azithromycin has been shown to be more effective than erythromycin and ciprofloxacin.
Udayraj said Cholera is an acute, highly transmissible, intestinal infection caused by toxigenic bacteria Vibrio cholerae. In its severe form, cholera is characterized by a sudden onset of acute voluminous watery diarrhea that can rapidly lead to dehydration and death if left untreated.
“Vibrio cholerae is a gram-negative non-invasive bacterium, but it produces a toxin responsible for the voluminous diarrhea. The bacteria can survive up to two weeks in water, several days in food at ambient temperature, and longer when the food is refrigerated or frozen,” she explained.
She added that Vibrio cholerae does not tolerate acid or dry conditions so boiling water assures complete killing. At the same time, chlorine is effective against Vibrio cholerae under proper conditions.
Cholera is commonly acquired from drinking water in which Vibrio cholerae is found naturally or that which has been contaminated by faeces of an infected individual. Low temperatures favours the survival of Vibrio cholerae in food.
“Foods including cold rice, raw vegetables, ice cream and fruits, undercooked or uncooked molluscs, shellfish and crustaceans contaminated in their natural environment have been implicated in cholera outbreaks,” she revealed.
The incubation period ranges from a few hours to five days. Patient presents with diarrhea (stools quickly lose their fecal content, taking on a characteristic “rice water” appearance and contain no blood).
Symptoms can range from simple watery diarrhea to massive watery diarrhea with losses of up to 500 to 1000 ml/hour in severe disease (20-30 per cent of all infected develop severe disease). The shedding of bacteria typically ends within seven to 10 days.
Udayraj said people with blood type O often get more severely ill from cholera than people of other blood types. Lower gastric acidity due to the use of H2 receptor blockers or proton pump inhibitors (omeprazole) increases susceptibility to infection.
Food also acts as an acid buffer. Introduction of vibrios into the intestinal tract stimulates immune response, providing natural immunity from six months to several years. Oral cholera vaccine induces immunity in the same manner, stated the medic.
“In endemic areas, children are more affected compared to adults as they have not yet developed the immunity that comes with repeated exposure,” Udayraj pointed out.
She revealed that since 2021, there has been an increase in cholera cases and their geographical distribution globally, with 23 countries reported cholera outbreaks, mainly in the WHO Regions of Africa and the Eastern Mediterranean. The number grew to 29 countries in 2022.
Many of those countries reported higher case numbers and deaths (Case Fatality Ratio- CFR) than in previous years, with an average of 1.9 per cent (2.9 per cent in Africa), well above acceptable.
She attributed the current upsurge of cholera to climate change, natural disasters, drought, cyclones, floods and monsoons among other reasons. People displacement, conflict, political instability as well as multiple ongoing emergencies (Covid-19, measles, monkey pox, Ebola, dengue fever).
Others include; Sub-optimal surveillance (data, alerts, laboratory capacity, heterogeneous case definition), Medical supply chain, Limited healthcare resources and Oral cholera vaccine shortage
Udayraj said the first case of cholera in Kenya was reported on 8th October 2022, following a wedding in Kiambu County. As at 5th February 2023, cumulatively there were 4,527 confirmed cases and 83 deaths (CFR 1.8 per cent).
In terms of Age and Sex Distribution of Cholera Cases and Deaths, she said there were a total of 2,311 (51 per cent) of the cumulative cases of males, while 2,215 (49 per cent) are females. Most cases 1,763 (39 per cent) are in the age group of 0-10 years. Of the 83 cumulative deaths, 65 (78 per cent) are males and 18 (22 per cent) are females.
On Children Under five years the data was; A total of 1352 (30 per cent) of the cumulative 4,527 cases, are children under five years. Of these, 650 (48 per cent) are less than 1-year-old, 727 (54 per cent) males and 625 (46 per cent) females. Of the cumulative deaths, 23 (28.0 per cent) were among the under five years
She added that the Distribution of Cholera Cases and Deaths by County was that of the 4,527 cumulative cases, 1,947 (44 per cent) are from Garissa County, followed by Tana River County with 718 (16 per cent). Nyanza which suffered perennial outbreak of cholera has been spared as only Bilharzia was reported in Seme, Kisumu County.
By Joseph Ouma