Marijuana against mosquito borne disease: Malaria

Malaria is an infection caused by protozoan organisms of the Plasmodium genus and transmitted by Anopheles mosquito species. Malaria can be fatal, although not all strains of the disease are equally lethal. The disease is said to have killed half of all humans to ever live, and continues to claim over a million lives annually.

Cannabis has a long history of use against diseases that cause symptoms of fever, such as cholera, rabies and tetanus. There are documented instances of use by ancient cultures including those of China and India; anthropologists have also documented traditional use which persists to this day among some African and Southeast Asian populations.

The early Chinese literature makes reference to cannabis being used as a treatment for malaria. Summarising its therapeutic properties, the Pen T’sao Ching states that cannabis ‘clears blood and cools temperature’, a reference to cannabis’ ability to reduce fever.

In Cambodia, individuals infected with malaria were traditionally treated with cannabis; such use may persist to this day, in some regions. Reportedly, the smoke from one kilogram of male and female plants is inhaled twice daily until the fever has passed. Occasionally, an alternative method is employed, whereby a preparation of cannabis and water is administered orally in two-milliliter doses prior to each meal. However, this method is held to be less effective.

In Africa, cannabis is reported to have been used by Zimbabwean traditional healers as a remedy for malaria, as well as for blackwater fever, a potentially-fatal complication of the disease. It is believed that traditional cannabis-based medicines continue to be in use among rural populations both in Africa and in Southeast Asia.

Use in traditional Indian medicine

In 1893-1894, the Indian Hemp Drugs Commission Report made reference to cannabis being used as a prophylaxis against malaria, administered in the form of ‘a cool refreshing drink’. At the time, cannabis was widely used in both the Ayurvedic (Hindu) and Tibbi (Islamic) branches of medicine as a hypnotic, analgesic and antispasmodic. The diaphoretic (perspiration-inducing) and diuretic properties of cannabis were considered effective in reducing fever.

In 1957, Indian doctors I. C. Chopra and R. N. Chopra published an in-depth report on the uses of cannabis in traditional Indian medicine. According to the report, cannabis was in common use ‘as a smoke and as a drink’ in malarial regions, where it was believed to be effective as a prophylactic. The submontane and Terai (savannah and grassland areas of northern India and Nepal) regions of Uttar Pradesh state, where wild cannabis is abundant, are specifically noted for their extensive use of bhang (a cannabis-based drink) as a treatment for malaria.

Bhang is believed to be more effective than ganja (herbal cannabis) in allaying the ‘general feeling of restlessness’ brought on by malarial fever. For medicinal purposes, it appears that cannabis was more commonly administered orally, and rarely by smoking. However, in some regions, hashish (colloquially known as nasha or charas) was smoked to both treat and prevent malarial headache.

Cannabidiol may prevent damage from cerebral malaria

Cerebral malaria is a severe and potentially-devastating complication of  P. falciparum infection, which can causes permanent neurological and behavioural deficits, even after infection resolution by antimalarial drugs. Cannabidiol (CBD), the major non-psychoactive cannabinoid found in C. sativa, has been repeatedly demonstrated to exert a neuroprotective effect, and has been shown to slow the rate of neurodegenerative diseases such as multiple sclerosis and Alzheimer’s disease.

A study published in 2013 aimed to investigate whether CBD could prevent behavioural changes in mice infected with P. berghei-ANKA—a species of Plasmodium that does not affect humans but will cause symptoms in many mammal species, and is a widely-used model organism for research purposes. Commencing three days subsequent to infection, some mice were injected with 30mg/kg doses of CBD.

Five days subsequent to infection, the infected mice were treated with artesunate, an established malaria treatment that works by reducing parasitemia (parasite load in the blood). After artesunate treatment and full reduction of parasitemia, the mice were subjected to memory and cognitive tasks. Mice that were solely administered with P. berghei-ANKA displayed memory deficits and increased anxiety, whereas mice treated with CBD did not display these effects. Although not replicated in humans, these results indicate that CBD could prove useful as an adjunctive therapy to reduce or entirely prevent brain damage caused by cerebral malaria.

The decline of traditional cannabis treatments for malaria

By the end of the 19th century, cannabis and hashish-based medications were in widespread use in the USA and Europe. Such treatments were in use for malaria, but their application for this purpose was apparently limited compared to their use in other areas of medicine. Of course, prohibition of cannabis dealt a fatal blow to its use in medicine, at least in the Western world.

The UN Single Convention on Narcotic Drugs (1961) was strongly protested by India and other sympathetic nations; indeed, in recognition of cannabis’ cultural significance, India was given twenty-five years to enact specific legislation. Despite this, the Chopra & Chopra report of 1957 stated that use of cannabis in Indian folk medicine had already begun to rapidly decline in the preceding decades.

However, at the time of the report it was observed that practitioners of indigenous medicine still made extensive use of cannabis in the rural areas of India, and that cannabis-based preparations remained popular household remedies for many minor ailments. Roving mendicants, still common throughout India, often carry and use bhang, and may still on occasion supply it to villagers in rural locations.