Risks of Sharing Needles: HIV and Syphilis Concerns

Sharing needles

Hello Doctor, I recently shared a needle for intravenous injection with an HIV patient.
What is the likelihood of infection? I used the needle at least an hour after he did.
I've seen various claims online about the virus survival time, ranging from 3 minutes to several hours; which one is correct? Additionally, how long after contracting syphilis will a rash appear on the arm? If someone contracts HIV, will a rash also appear on the arm, or is it only on the front of the body? Will the appearance of the rash be similar to that of syphilis?

Xiao Kai, 20~29 year old female. Ask Date: 2022/12/21

Dr. Hong Yuanbin reply Internal Medicine

Hello, sharing needles can lead to infection regardless of how long they have been used; even if it’s just for one minute, there is still a risk of infection.
Therefore, never use needles that have been used by someone else.
The so-called rash is associated with the secondary stage of syphilis, which typically occurs approximately six weeks to six months after infection.
HIV infection may present symptoms similar to those of the flu, and a rash is not always present.
The appearance of the rash may not necessarily resemble that of syphilis.
It is advisable to get tested for HIV as soon as possible if you have shared needles and are feeling unwell.
Thank you for your question.

Reply Date: 2022/12/21

More Info

When it comes to understanding the risks associated with sharing needles, particularly in the context of HIV and syphilis, it is crucial to have accurate information about transmission routes and the behavior of these viruses outside the human body.

Firstly, sharing needles with an HIV-positive individual poses a significant risk for transmission. HIV is primarily transmitted through blood, and sharing needles or other injection equipment can lead to direct exposure to the virus. The risk of infection is particularly high if the needle has recently been used, as HIV can survive in a used needle for a period of time. While various sources may suggest different survival times for HIV outside the body, research indicates that HIV can remain viable in a syringe for several hours, depending on environmental conditions. Therefore, using a needle that was previously used by someone else—even after an hour—still carries a risk of infection.

Regarding syphilis, it is important to note that this sexually transmitted infection (STI) is primarily spread through direct contact with syphilis sores during sexual activity. While syphilis can also be present in blood, it is less commonly transmitted through needle sharing compared to HIV. If you are concerned about syphilis, it is essential to monitor for symptoms, which may include a rash, sores, or other signs of infection. The timeline for the appearance of a rash after syphilis infection can vary, but it typically occurs within a few weeks to a few months after exposure.

If you are infected with HIV, the symptoms can vary widely. Some individuals may experience acute retroviral syndrome (ARS) within 2 to 4 weeks after infection, which can include flu-like symptoms such as fever, fatigue, and rash. The rash associated with HIV can appear on various parts of the body, including the arms, torso, and face, and may not necessarily resemble the rash associated with syphilis. The appearance of the rash can differ significantly between individuals and may not be the same as the rash seen in syphilis.

In summary, sharing needles with an HIV-positive person carries a high risk of transmission, and the viability of HIV in used needles can last for several hours. If you have shared needles, it is advisable to get tested for both HIV and syphilis as soon as possible. Early detection and treatment are crucial for managing these infections effectively. If you notice any unusual symptoms, such as rashes or sores, seek medical attention promptly. Regular testing and practicing safe injection techniques are essential for reducing the risk of HIV and other STIs.

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