Although chlamydia is highly contagious, it does not always transmit to a person’s sexual partners. It is also possible to have a false-negative or false-positive test result.
Having more frequent sex with a partner who has chlamydia may increase a person’s risk of contracting it. Despite this, a person with chlamydia can have frequent sex without the infection passing to their partner.
If a person takes a test too soon after exposure, they may have a false-negative result. They may need to repeat the test at a later date to get an accurate result.
Read on to learn why one partner may test negative for chlamydia when the other tests positive.
If one partner tests positive for chlamydia and the other does not, there are a few possible explanations:
- The positive test result could be incorrect.
- The negative test result could be incorrect.
- The chlamydia might not have transmitted from the person to their partner.
Simply knowing that one partner is positive and the other is negative does not reveal anything about the status of the relationship. Having different test results does not necessarily mean that one partner has been unfaithful.
It also does not mean that the partner who tested negative is immune. They might eventually develop chlamydia or another sexually transmitted infection (STI).
A person will not contract chlamydia every time they have sex with someone with the infection. In a 2020 study, researchers developed a model for estimating how likely a person is to get chlamydia from a partner with the infection. Using two different sets of data, this model gave the following per-partnership transmission rates:
- male to female: 32.1% and 34.9%
- female to male: 21.4% and 4.6%
The study did not look at transmission rates between people of the same sex.
Chlamydia spreads through sexual contact with bodily fluids containing the bacteria. Some types of sexual activities that can spread chlamydia include:
- vaginal intercourse
- anal intercourse
- oral sex
- anal-oral contact
People with chlamydia often
A person with a history of recent exposure to chlamydia should undergo testing. They should act as though they have the infection until a healthcare professional tells them otherwise.
In some cases, a person may also have a false-negative test result. This can happen if they test too soon after exposure. For example, if a person tests the day after sex with a partner who has chlamydia, the bacteria may not have had the chance to grow to detectable levels.
It can take
A 2014 systematic review to update the United States Preventive Services Task Force guidelines for chlamydia screening suggests a false-negative rate in the range of
Across all studies, regardless of study quality, the false-positive rate ranged from 0% to 2.9%.
This means that if one partner tests positive and the other tests negative, it is more likely that the negative partner has an inaccurate test result. In many cases, it makes sense to treat both partners even when just one tests positive.
Talking about STIs can be uncomfortable and embarrassing. If one person tests positive and their partner does not, they may worry about infidelity. It is important to know that having different test results does not definitively mean this is the case.
It can be helpful to discuss chlamydia with a healthcare professional to understand each partner’s risk.
Some topics to talk about with one another include:
- whether both partners are and have been monogamous
- mutual reassurance and support
- a treatment plan
- whether and when to retest
- whether to abstain from sex and for how long
It can be confusing if one partner tests positive for chlamydia or another STI and the other does not. However, this can happen for many reasons, including false positives and false negatives.
Even the most contagious STIs do not transmit from one partner to another every time they have sex. It is important to discuss STI test results with a healthcare professional to develop an appropriate treatment plan.