Fatigue, to some extend, is one of the most common symptoms of diseases in general as well as of parasitic infections. This symptom is characterised by a desire to rest combined with lack of energy to pursue normal activities. It is a usual body reaction when experiencing an infection as energy is derived toward the fight against the intruder. As such, it is known to be a common transient condition during the course of an infection and this symptom usually resolved by itself while the infection is treated.
However, if unexplained fatigue is experienced for more than 6 months, it could also be what is called the chronic fatigue syndrome. However, this infrequent condition is actually not well understood and still not fully explained by scientific research. In fact, the real causes of the chronic fatigue syndrome are still unknown, but many inconclusive hypotheses have been explored so far to explain it. As such, many more research will be required to understand the real causes of the chronic fatigue syndrome. It is also very likely that many different factors might be responsible for this condition, meaning that many type of microorganisms along with other factors might be responsible individually for the chronic fatigue syndrome depending on the patient’s history. As such, parasites could be (or not) a cause of the chronic fatigue syndrome and further research will be needed to validate this hypothesis.
Actually, many viruses and bacteria have been proposed to be involved in the chronic fatigue syndrome, but further research will be needed to prove the link between these pathologies. Hormonal and immunological imbalances have also been suspected to play a role in the development of the chronic fatigue syndrome.
The link between this condition and parasitic infections has not yet been explored extensively. As such, few studies are available in the scientific literature to assess this potential link. However, a recent study linked cases of the chronic fatigue syndrome occurring within 5 years with a major waterborne outbreak of Giardia intestinalis in Norway. Other parasitic suspects, such as roundworms, have been suggested as a cause of the chronic fatigue syndrome, but there is actually no solid scientific proof to back these claims.
It is simply a hypothesis here but, as mentioned earlier, one of the possible causes of the chronic fatigue syndrome is immunological dysfunction. As parasites are known to modulate the host’s immune system, it could be interesting to study this effect as a potential link between parasites and the chronic fatigue syndrome.
Finally, even though fatigue is a known symptom of parasitic diseases, it is likely that parasites have finally nothing to do with the chronic fatigue syndrome. In fact, as no cause for this condition has been discovered so far, it is totally possible that further research will point to a single non-microorganism related cause. However, this possibility seems unlikely and multifactorial causes are now the main hypotheses to explain the chronic fatigue syndrome.
Sources: Merck Manual; Mørch, K. et al. (2013). Chronic fatigue syndrome 5 years after giardiasis: differential diagnoses, characteristics and natural course. BMC gastroenterology, 13(1), 28.