The types of diseases that are spread and can be spread by using injected syringes are fungal diseases, bacterial diseases, hepatitis B and even Hepatitis C.
HIV can also be possibly spread by using injected syringes, if the syringes are reused on more than one person or to access any vials that are shared between patients.
Blood borne diseases can be spread through sharing the same needles and injected syringes.
So it's important to never share injected syringes or needles with anyone even if you know them or even if they are family.
A new syringe or needle should always be used even if it's on yourself and never share needles with others and always dispose of the used needles and syringes properly and safely to avoid someone else getting pricked up the needles or syringes which can also transmit any disease that way as well.
Always wash your hands after using a syringe or needle and especially when injecting someone else and if injecting someone else with an injected syringe or other needle or giving someone an IV always wear gloves.
Unsafe injection practices may result in serious consequences like the transmission of bloodborne pathogens such as hepatitis C virus (HCV), hepatitis B virus (HBV), and human immunodeficiency virus (HIV).
Viral hepatitis, HIV, and other blood-borne pathogens can easily spread through injection drug use if people use needles, syringes, or other injection materials that were previously used by someone who had one of these infections.