The threat of communicable disease is a hazard in performing first aid. You should follow some standard precautions (called universal precautions) and use personal protection equipment like gloves, a CPR barrier, or eye protection.
Universal precautions protect aid providers from exposure to HIV (the virus that causes AIDS), hepatitis B, and other blood-borne germs when exposed to blood, certain body fluids (including semen and vaginal fluid), and tissue from anyone who is infectious. Universal precautions should also be taken for cerebrospinal (from the lining of the brain and spinal cord), synovial (joint), pleural (lung), peritoneal (abdominal), pericardial (heart), and amniotic (pregnant uterus) fluids.
These guidelines don't apply to other body fluids like saliva, urine, sweat, tears, nasal secretions, sputum, and feces unless they contain blood. Professional universal precautions include:
Wash your hands before and after any medical intervention.
Wear gloves whenever you are in contact with another's blood, body secretions, or tissues even if the person you are helping is a family member.
Wear a facemask or body gown whenever there is a possibility of blood splashing onto the rescuer.
Dispose of contaminated sharp objects in the appropriate puncture-proof container.
Dispose of all contaminated equipment in an appropriate biohazard container.
Universal precautions mean you are to be careful and not take chances; it doesn't mean that you don't provide care!
While you may not have all the equipment necessary, these professional guidelines will steer you in the right direction. As a layperson, you should try and follow these precautions as closely as possible.
Rescuer using gloves as a protective barrier
Practice universal precautions when coming in contact with blood or any body secretions or fluids that may also contain blood to protect your own health and even save lives.
To carry-out universal precautions against infectious disease, you should use a protective barrier when you are providing care to anyone, even if you know the person well. In this day and age, it's just common sense to avoid contact with an unknown potential source of infection.
If you don't have gloves, improvise and use something like plastic wrap and wash your hands thoroughly before and after providing any care.