Human herpesvirus 6
Human herpesvirus 6 (HHV-6) is a set of two closely related herpesviruses, HHV6-A and HHV6-B. Infection is extremely common and usually occurs at an early age. 64-83% of infants are infected by age 13 months. HHV-6 has an affinity for leukocytes and nervous tissue, especially the olfactory bulb tissues, from which it is thought to disseminate to other parts of the brain. After infection the virus remains latent but can reactivate asymptomatically even in healthy individuals.
In human disease
Antivirals may have some therapeutic benefit. A randomized, placebo-controlled double-blind study found that acyclovir reduced the exacerbation rate in relapsing-remitting MS patients.. Valacyclovir reduced new lesions in patients with high disease activity.
Chronic fatigue syndrome
One study found a higher prevalence of past HHV-6 infection in chronic fatigue syndrome patients but with a low viral load that did not suggest reactivation. Several studies have found that active infection is more common in CFS patients than healthy controls.
- 2016, Human herpesvirus 6 and 7 are biomarkers for fatigue, which distinguish between physiological fatigue and pathological fatigue
- 1994, Prevalence of Human Herpesvirus 6 Variants A and B in Patients with Chronic Fatigue Syndrome
- Pietiläinen-Nicklén J, Virtanen JO, Uotila L, Salonen O, Färkkilä M, Koskiniemi M. (2014). HHV-6-positivity in diseases with demyelination. Journal of Clinical Virology, 61 (2):216-9. doi: 10.1016/j.jcv.2014.07.006. Epub 2014 Jul 21. Rerieved from http://www.ncbi.nlm.nih.gov/pubmed/25088617
- Aoki, R; Kobayashi, N; Suzuki, G; Kuratsune, H; Shimada, K; Oka, N; Takahashi, M; Yamadera, W; Iwashita, M; Tokuno, S; Nibuya, M; Tanichi, M; Mukai, Y; Mitani, K; Kondo, K; Ito, H; Nakayama, K (2016), "Human herpesvirus 6 and 7 are biomarkers for fatigue, which distinguish between physiological fatigue and pathological fatigue", Biochemical and Biophysical Research Communications, 478 (1): 424-30, PMID 27396623, doi:10.1016/j.bbrc.2016.07.010