Hello!
Based on your personal experience, what do you think is CFS contagious? And I am referring to CFS not to EBV (mononucleosis) which we know it is transmissible through saliva.
If you think is transmissible, how can it be transmitted? Through saliva, sexually, by air, water, food, etc?
In case you think is transmissible sexually what is the sexual life of the CFS patient? Can she/he still make sex, and thus put the partner on risk? Even using condoms, that is not 100% safe, and if just saliva is enough to transmit the disease, that is very bad.
Gingergrrl is correct to mention blood transfusion ban, such as in the UK. This also includes umbilical cord material from women. Post Viral Fatigue Syndrome (PVFS) a diagnosis that was made in the past before 'CFS' was created, these patients also cannot donate bone marrow, even when dead. So I'd take that on board in terms of potential risk.
However, there is no real safety information relayed to the public, so it's hard to say. CFS doesn't exist as one entity, it's a collection of symptoms, so in short answer, no CFS isn't contagious or an STD because you can't pass something the CDC created based on an individual meeting criteria of unexplained chronic fatigue.
However, within CFS are often misdiagnosed organic conditions, some of an ifection based nature, such as Lyme disease (which does have some evidence of transmission). In addition we don't know if ME (trapped within CFS, via 'CFS/ME' that the British created) is involved with pathogens no one has discovered yet. These could be anything from prions, bacterias, viruses and retroviruses. Retroviruses are passed on in DNA to the baby, but this is very controversial issue in 'CFS', as the research is never performed by government scientists, only independent scientists, who then have their careers ruined and their science discredited of any chance of an exogenous retrovirus being associated to CFS. (See Elaine De Freitas, Judy Mikovits). Times may change, and we might in the future see evidence of pathogenic HERV's (Human endogenous retroviruses), being associated to multiple autoimmune illnesses, and also CFS.
Without the correct cohorts of patients with signs of disease researched in repeat large scale studies (Using Fukuda criteria CFS is insufficient to gather meaningful data on any pathogen found), we can only speculate as to how 'it' is transmitted in CFS (if at all), but this doesn't get us any closer to the facts, because 'it' will never be the same for everyone with a CFS diagnosis because of the heterogeneous nature of the illness.
In very basic terms if an individual had a diagnosis of CFS, and this person was immune suppressed in a manner science currently didn't understand and was unaware they were harbouring intracellular bacterial infections, then they could pass anything onto others people from Borrelia, it's co infections, and/or viruses such as EBV from kissing for example. CFS patients don't appear to respond correctly to EBV, and EBV is highly contagious as is Chlamydia Pneumoniae, also found in CFS and Lyme sufferers.
Even today, it was in the press that an estimated 1% of the UK population is estimated to have Mycoplasma Genitalium, which is thought of an an STD. If 'CFS' patients have this infection at a higher rate than the average person, no one knows.
So anything is possible in 'CFS' in terms of future pathogen discovery, but we should remember that 'CFS' doesn't exist as a single evidence based diagnosed condition, so there will always have multiple reasons behind 'Fatigue' in CFS that may or may not be transmittable.
As for your question:
In case you think is transmissible sexually what is the sexual life of the CFS patient?
Can she/he still make sex, and thus put the partner on risk
No one knows the answer to that question, until we find out if previously undiscovered infections exist in CFS, and how they work in the human body, it cannot be answered with any accuracy.
The only evidence I would say exists for this 'risk' in CFS, is quite a lot of folk with CFS diagnosis find out they actually have Lyme disease (Borrelia infection), and on that basis, yes, it may be transmissible, and thus whenever possible, use contraception anyway when engaging in sexual activity, as simple common sense rule whether someone is sleeping with an individual with CFS, or a healthy individual.
When it comes to sex, I would be careful rather than careless, but also mindful there is no evidence that CFS or ME for some sufferers, is a disease which may carry an additional new to science STD, or an infection passed on to others by airborne contagion such as sneezing. This doesn't mean the science won't change though in the future.
But as it stands, there is no evidence, so I wouldn't worry. Use contraception and wherever possible, enjoy your life.