Hip
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Human herpes virus 7 (HHV-7) infection is rarely considered by ME/CFS patients or their doctors, yet active infection with this member of the herpesvirus family has been linked to ME/CFS in several studies.
Just like the other main viruses liked to ME/CFS (namely EBV, HHV-6, CMV, enteroviruses and parvovirus B19), studies have shown that ME/CFS patients more frequently have high titers to HHV-7 compared to healthy controls. These high titers suggest active infection, and thus implicate HHV-7 in the pathophysiology of ME/CFS.
For example, this study found that HHV-7 was active in 53% of ME/CFS patients, either as single infection, or in combination with other active viruses like HHV-6. Whereas only 11% of the health controls were found to have active HHV-7 (see Table 1).
What's more, dual active infections with both HHV-6 and HHV-7 were only detected in ME/CFS patients in that study; none of the healthy controls had dual active infections. This finding of dual active HHV-6 and HHV-7 only in ME/CFS patients but not in healthy controls was also observed in this study.
Yet to my knowledge, none of the ME/CFS specialist doctors regularly test for HHV-7 in their ME/CFS patients. Certainly there is very little discussion of HHV-7 on this forum. In the past, HHV-7 tests were not commercially available, possibly explaining why this virus has been ignored; but an IgG and IgM antibody test for HHV-7 is now available from Quest.
Furthermore, from some pharmacokinetic calculations I did, it appears that neither Valtrex nor Valcyte has any antiviral activity against HHV-7 in vivo. Famvir does not work for HHV-7 either.
This study says: "oral ganciclovir and treatment with IV ganciclovir had no effect on the prevalence of HHV-7 viremia ... these results indicate that HHV-7 is resistant to ganciclovir".
This study says: "ganciclovir is unlikely to be effective against HHV-7-related CNS disease, foscarnet may be useful but prospective trials are needed".
So if your ME/CFS doctor tests you for the usual ME/CFS viruses, and if your test results show, for example, an active infection with EBV, HHV-6 and/or CMV, the doctor may prescribe you Valtrex or Valcyte to treat these active viral infections.
Valtrex or Valcyte often lead to major improvements in ME/CFS patients who have one or more of these herpesviruses as active infections (after around 1 year or so of antiviral therapy). But other patients don't seem to benefit much.
The reason some patients don't benefit could be because they also have an active HHV-7 infection, which these two antivirals don't target. But your doctor will not know whether you have active HHV-7, because he will not have tested for it, and thus may never suspect HHV-7 as a reason why Valtrex or Valcyte were unable to improve your ME/CFS.
So an active HHV-7 infection could be a hidden factor behind the failure of some patients to properly respond to Valtrex or Valcyte, because even though these antiviral may bring other herpesviruses under control, they don't work for HHV-7, and so your HHV-7 infection may remain active, and continue to cause ME/CFS symptoms.
The good news though is that the intravenous antivirals cidofovir (Vistide) and foscarnet (Foscavir) are potent antivirals for HHV-7, especially foscarnet (at least that's what my pharmacokinetic calculations showed, assuming these calculations are correct — I will be posting these calculations on the forum soon).
So if you did have an active HHV-7 infection, along with some other concurrent active herpesvirus infections, then cidofovir or foscarnet could target all your herpesviruses; these two antiviral are potent for EBV, HHV-6, cytomegalovirus, HSV-1, HSV-2 and HHV-7. Dr Daniel Peterson has experience using cidofovir for ME/CFS (some info here).
But I guess my question is: why are the ME/CFS specialist doctors often neglecting to test for HHV-7, when studies have implicated this virus in ME/CFS?
Just like the other main viruses liked to ME/CFS (namely EBV, HHV-6, CMV, enteroviruses and parvovirus B19), studies have shown that ME/CFS patients more frequently have high titers to HHV-7 compared to healthy controls. These high titers suggest active infection, and thus implicate HHV-7 in the pathophysiology of ME/CFS.
For example, this study found that HHV-7 was active in 53% of ME/CFS patients, either as single infection, or in combination with other active viruses like HHV-6. Whereas only 11% of the health controls were found to have active HHV-7 (see Table 1).
What's more, dual active infections with both HHV-6 and HHV-7 were only detected in ME/CFS patients in that study; none of the healthy controls had dual active infections. This finding of dual active HHV-6 and HHV-7 only in ME/CFS patients but not in healthy controls was also observed in this study.
Yet to my knowledge, none of the ME/CFS specialist doctors regularly test for HHV-7 in their ME/CFS patients. Certainly there is very little discussion of HHV-7 on this forum. In the past, HHV-7 tests were not commercially available, possibly explaining why this virus has been ignored; but an IgG and IgM antibody test for HHV-7 is now available from Quest.
Furthermore, from some pharmacokinetic calculations I did, it appears that neither Valtrex nor Valcyte has any antiviral activity against HHV-7 in vivo. Famvir does not work for HHV-7 either.
This study says: "oral ganciclovir and treatment with IV ganciclovir had no effect on the prevalence of HHV-7 viremia ... these results indicate that HHV-7 is resistant to ganciclovir".
This study says: "ganciclovir is unlikely to be effective against HHV-7-related CNS disease, foscarnet may be useful but prospective trials are needed".
So if your ME/CFS doctor tests you for the usual ME/CFS viruses, and if your test results show, for example, an active infection with EBV, HHV-6 and/or CMV, the doctor may prescribe you Valtrex or Valcyte to treat these active viral infections.
Valtrex or Valcyte often lead to major improvements in ME/CFS patients who have one or more of these herpesviruses as active infections (after around 1 year or so of antiviral therapy). But other patients don't seem to benefit much.
The reason some patients don't benefit could be because they also have an active HHV-7 infection, which these two antivirals don't target. But your doctor will not know whether you have active HHV-7, because he will not have tested for it, and thus may never suspect HHV-7 as a reason why Valtrex or Valcyte were unable to improve your ME/CFS.
So an active HHV-7 infection could be a hidden factor behind the failure of some patients to properly respond to Valtrex or Valcyte, because even though these antiviral may bring other herpesviruses under control, they don't work for HHV-7, and so your HHV-7 infection may remain active, and continue to cause ME/CFS symptoms.
The good news though is that the intravenous antivirals cidofovir (Vistide) and foscarnet (Foscavir) are potent antivirals for HHV-7, especially foscarnet (at least that's what my pharmacokinetic calculations showed, assuming these calculations are correct — I will be posting these calculations on the forum soon).
So if you did have an active HHV-7 infection, along with some other concurrent active herpesvirus infections, then cidofovir or foscarnet could target all your herpesviruses; these two antiviral are potent for EBV, HHV-6, cytomegalovirus, HSV-1, HSV-2 and HHV-7. Dr Daniel Peterson has experience using cidofovir for ME/CFS (some info here).
But I guess my question is: why are the ME/CFS specialist doctors often neglecting to test for HHV-7, when studies have implicated this virus in ME/CFS?
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