The International Association for Medical Assistance to Travellers (IAMAT) states on its website that users of cannabis are “more susceptible to cholera infection”. However, cannabis has been used throughout history to both treat and prevent cholera. Does IAMAT have its facts wrong, or is there a deeper relationship at work?
Cholera is a bacterial illness that primarily affects the small intestine, causing watery diarrhoea and vomiting. If left untreated, it can lead to extreme dehydration and can be fatal. Cholera is caused by the Vibrio cholerae bacterium, and is transmitted by ingesting contaminated water or food.
Diarrhoea and vomiting occur due to the action of a toxic protein (known as the cholera toxin, or CT) secreted by the bacterium. It stimulates the cells of the small intestine and causes them to exude a clear, watery liquid in huge quantities.
How is cholera transmitted?
An infected person may produce 10-20 litres of diarrhoea per day, leading to severe dehydration. The diarrhoea acts as a reproductive vehicle. It contains new generations of the bacterium, which in areas with poor sanitation, may end up in the water supply where they can infect a new host.
Although cholera has been all but eradicated in the developed world, cases still occasionally occur. In the developing world, where sewerage and clean drinking water are beyond reach of large sections of the population, cholera remains a deadly threat.
According to the World Health Organization, cholera has an estimated incidence of 1.3 – 4 million people worldwide. Anywhere between 21,000 and 143,000 people die worldwide as a result of cholera.
Cannabis and susceptibility to cholera
The basis of IAMAT’s claim is that smoking cannabis “reduces acid secretion of the stomach”, which in turn lessens the body’s defence against V. cholerae bacteria. Existing research supports cannabis’ ability to inhibit gastric acid secretions, although there are few studies that specifically assess the relationship between cannabis use and susceptibility to cholera itself.
A relationship between low gastric acid levels (hypoacidity) and susceptibility to cholera has also been demonstrated. If stomach acid is too low, the bacteria are more easily able to pass through into the small intestine, and will do so in greater numbers. Indeed, stomach acid is seen as the first line of defence against cholera.
Cannabis, hypochlorhydria and cholera
This study, published in the Lancet in 1978, does attempt to describe a relationship between cannabis, gastric secretions and cholera. The study subjected 92 volunteers to E. coli and V. cholerae bacteria. During preliminary testing, the researchers discovered that the heavy cannabis users among the group had lower levels of gastric acid, and that heavy beer drinkers had the highest levels.
The study also found that individuals with low gastric acid experienced more severe diarrhoea once infected with V. cholerae. The study concluded that heavy cannabis use was associated with increased volume of diarrhoea, and that cannabis use “may be an important factor predisposing to severe diarrhoea”.
Cannabis as a cure for cholera
Throughout history, there have been documented cases of physicians and traditional doctors prescribing cannabis to alleviate the symptoms of cholera. Considering historical and modern sources, there has been persuasive evidence that suggests that the endocannabinoid system can be used for pharmacological intervention of cholera.
In India, the physician William B. O’Shaughnessy reported in 1839 that cholera could be treated with cannabis. In 1893, the India Hemp Commission reported that cannabis was used to treat cholera by traditional folk healers, as well as to act as a protection against infection by the bacterium.
The 1868 edition of the U.S. Dispensatory, a highly influential pharmacopoeia of the time, also specifically recommends cannabis as a treatment for cholera.
Dr Willemin’s cannabis tincture cure
One paper presented to the Académie de Médecine in Paris outlines one doctor’s use of cannabis to treat cholera. The man in question was Dr Willemin, a German physician living and practising in Cairo around 1848. During a bout of cholera, he used cannabis to treat himself and others who had fallen extremely ill to the disease.
Willemin’s theory was that cannabis ‘stimulated’ the nervous system, reversing the ‘paralysing’ effect of cholera—typified by a weakened pulse, cold, numb limbs, and blueish-hued skin from extreme dehydration. He also suggested that the effect could be dose-dependent, as earlier patients had been administered a lower dose and had died, despite their symptoms being less severe.
While he was unable to fully describe the mechanism, modern research has borne out the idea that cannabis ‘stimulates’ the cannabinoid receptors of the enteric nervous system. This may indeed assist in reversing the extreme signs of dehydration by reducing excess fluid secretion in the small intestine.
Modern research on cannabis and cholera
Only a few studies specifically analysed the effect of cannabinoids on the symptoms of cholera. However, a 2003 study on cholera-related fluid secretions in mice demonstrates the complexity of the relationship. Researchers found that mice orally administered with cholera toxin (CT) exhibited increased CB1-receptor activity and increased levels of the endocannabinoid anandamide.
It was also demonstrated that two synthetic CB-receptor agonists worked to decrease CT-induced fluid secretions in the small intestine: the THC analogue CP55,940 (a non-selective agonist) and arachidonoyl-chloro-ethanolamide or ACEA (a selective CB1-receptor agonist).
A selective CB2-receptor agonist, JWH-015, was found to have no inhibitory effect on fluid secretions. Furthermore, mice treated solely with the antagonist SR141716A exhibited increased fluid secretions.
CB1-receptor agonists decrease fluid secretions
The researchers also discovered that the effects of both CP55,940 and ACEA were counteracted by a CB1-receptor antagonist, but not by a CB2-receptor antagonist. From this, the researchers were able to conclude that the inhibitory effect on cholera-related fluid secretions is mediated solely by the CB1-receptor.
The researchers concluded that, in cases of cholera infection that also involved excess fluid accumulation, the CB1-receptor is overstimulated, causing an increase in levels of the endogenous agonist anandamide. The result is an inhibitory effect on fluid secretions, thereby reducing diarrhoea.
While this would appear to contradict the idea that cannabis use predisposes an individual to more severe diarrhoea, these results have not yet been replicated in humans, so a firm conclusion cannot be drawn.
Cannabis extracts may kill cholera bacteria
Another study, published in 2012, demonstrated that acetone and aqueous extracts of cannabis were effective in killing V. cholerae bacteria in vitro. Sterile Petri dishes of agar jelly were infected with the bacteria, and paper discs soaked in cannabis extract were then introduced into the Petri dish.
After being stored for some time at human body temperature, the inhibition zone (the area in which bacteria had been killed) around the extract-soaked discs was measured. The researchers found that the acetone extract exhibited the strongest antibacterial effect, and that the zone of inhibition surrounding both extracts increased as concentration increased (from 5µg/ml to 10µg/ml).
Implications for healthcare
Recent research demonstrating that hemp textiles are effective in killing Klebsiella pneumonia and staphylococcus aureus bacteria supports the research presented in this article. Together, they may prove crucial in the future development of approaches to managing these highly contagious and potentially devastating diseases.
Furthermore, perhaps this property is the basis for the traditional use of cannabis as a prophylactic against cholera infection. If a tea or tincture contains cannabinoids in sufficient concentration, regular consumption could potentially play a role in controlling any V. cholerae bacteria ingested.
However, our knowledge of the antibacterial effects of cannabinoids is in its infancy, and more research will need to be done before this question can be answered.
Is cannabis a treatment or a risk factor?
In the 1978 study mentioned earlier in this article, cannabis and alcohol were prohibited from the study ward. This means that any potential curative effect of cannabis on individuals already infected with V. cholerae was not measured. It may even prove to be the case that abrupt cessation of cannabis use worsened the symptoms of diarrhoea experienced by regular heavy smokers.
There may also be a dose-related explanation for the seemingly opposite results of the various existing studies. Cannabis has been shown to have very different effects when administered at high or low doses; this seems to hold particularly true for gastrointestinal function.
In small doses, some of Dr Willemin’s earlier patients died, but in higher doses, even those in more advanced stages of the disease survived. The research into the antibacterial effect of cannabinoids demonstrates again that cannabis extracts are more effective at higher doses.
Certainly, cannabis has a complex effect on the gastrointestinal system. Our understanding of the separate and synergistic effects of the various different cannabinoids is still in its infancy, and until we achieve deeper insight, many questions will remain incompletely answered or unanswered entirely.
As many of those still at risk of cholera reside in countries that also have a well-established culture of cannabis use, it would be highly advantageous to gain full understanding of the complex relationship at work here. In this way, we may be able to benefit from its potentially protective and curative effects.
- Disclaimer:This article is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with your doctor or other licensed medical professional. Do not delay seeking medical advice or disregard medical advice due to something you have read on this website.