Lyme Disease, Malaria and Covid Long: A Possible Histamine Link?

Histamine, Lyme Disease and Malaria: An Underestimated Immune Link

Lyme disease and malaria, although very different in appearance, share a crucial point in common: histamine, a key player in the body's immune and inflammatory response. Histamine plays a central role in both diseases, modulating the body's immune response to infections, often with significant side effects. But what is this link, and how can it help us to better understand these diseases?

Histamine and malaria

Malaria, particularly neuromalaria, is a severe form of the disease caused by Plasmodium falciparum in humans. The severe neurological manifestations associated with neuromalaria are still difficult to explain, but they appear to be linked to disruption of the blood-brain barrier (BBB) and inflammation of the brain. One of the underlying causes is the release of histamine. During parasite invasion, this release causes neuronal inflammation and adhesion of infected red blood cells to vascular walls, increasing brain damage.

The effects of histamine vary according to the receptors activated (H1, H2, H3, H4) and the cell types involved, whether immune cells or nerve fibers. Histamine can have both pro- and anti-inflammatory effects. For example, activation of the H3 receptor in the central nervous system inhibits the release of histamine and other neurotransmitters such as dopamine and serotonin. This explains the neurological symptoms of malaria, such as cognitive impairment, sleep disorders and mood swings.

Histamine and Lyme disease

Lyme disease, caused by the bacterium Borrelia burgdorferi, is also marked by histamine release, although its link is less studied than that with malaria. Ticks, the vectors of this disease, cause an accumulation of basophils at sites of infection, promoting localized histamine release. This may explain some of the allergic and inflammatory symptoms observed in Lyme patients.

Lyme patients often develop specific IgE antibodies against the bacterium, which could promote an excessive histamine-mediated inflammatory response, particularly in cases of reinfestation or chronic infection that is not promptly treated. Symptoms of Lyme disease, including joint pain, neurological disorders and arthritis, are similar to the inflammatory effects of histamine, suggesting that this molecule may play a central role in the pathogenesis of the disease.

A possible link with Covid Long?

Interestingly, the results of studies on Lyme disease and malaria show similarities with observations made in patients with long Covid. Covid-19 also appears to activate mast cells and histamine release, notably via interleukin-1. This suggests that histamine may be a key factor in the excessive immune response observed in some Covid patients, particularly those with persistent symptoms.

Conclusion

Histamine, often relegated to the background in the treatment of infectious diseases, deserves particular attention. It appears to play a central role in diseases such as malaria, Lyme disease, and perhaps even Covid longus. Understanding its effects on the immune and inflammatory systems could open up new avenues of treatment for these diseases. Instead of focusing solely on the pathogenic response, it could be beneficial to better target histamine regulation to improve patient outcomes.