Trichomoniasis, commonly known as “trich,” is a widespread sexually transmitted infection. People often wonder if one partner can test positive while their sexual partner tests negative. This discrepancy can occur, and understanding trichomoniasis testing and influencing factors helps clarify why. This article explores the reasons for differing test outcomes between partners and outlines recommended steps.
Understanding Trichomoniasis Testing
Diagnosing trichomoniasis relies on various laboratory methods for detecting the parasite Trichomonas vaginalis. Nucleic Acid Amplification Tests (NAATs) are the most sensitive and specific diagnostic tools. These tests identify the parasite’s genetic material, even in small amounts. NAATs can be performed on urine samples, vaginal swabs, or endocervical swabs, offering flexible collection methods.
Other diagnostic approaches include wet mount microscopy, examining a fresh sample for motile trichomonads. While quick and inexpensive, its sensitivity is significantly lower, detecting only about 50-70% of infections. Rapid antigen detection tests and culture methods are also available but are used less frequently than NAATs due to lower sensitivities or longer turnaround times. The chosen testing method can influence detection, especially with low parasite concentration.
Reasons for Differing Test Results
Several factors can contribute to one partner testing positive for trichomoniasis while another tests negative. One primary reason relates to the diagnostic test’s sensitivity. For instance, if one partner undergoes a highly sensitive NAAT (95-99% sensitive) and the other receives a less sensitive wet mount (as low as 25% sensitive), the latter might receive a false negative result.
The timing of testing relative to exposure plays a role. Testing too early, before the parasite load is sufficient for detection (e.g., within the 5-28 day incubation period), can lead to a false-negative result. Trichomoniasis can also exhibit intermittent shedding, where the parasite is not consistently present or detectable. This can lead to a negative result even in an infected individual, making detection challenging.
Re-infection is another consideration. If one partner was previously treated but re-exposed by an untreated or new partner, a re-infected individual could test positive while another partner tests negative. Approximately 1 in 5 people treated for trichomoniasis become infected again within three months, often due to an untreated partner. Biological variations, like immune response or sample collection, might also influence detectability. While rare, a false positive result for one partner could also explain a discrepancy.
Guidance Following Discrepant Results
When partners receive conflicting trichomoniasis test results, both individuals should receive treatment. This prevents re-infection of the positive partner and treats the potentially infected but undiagnosed partner, interrupting the transmission cycle. Treatment typically involves a single dose of metronidazole or tinidazole. Even if one partner tests negative, concurrent treatment for both is standard practice to ensure parasite eradication and prevent ping-pong infections.
Following treatment, retesting may be advised, especially for women, to confirm infection clearance and identify re-infection. This retesting typically occurs within three months after treatment; testing too soon (e.g., within 3-4 weeks) can lead to false positive results from non-viable organisms. Open communication about test results and treatment plans is important for effective management.
Engaging in safe sex practices, like consistent condom use, can reduce the risk of future sexually transmitted infections. Both partners should abstain from sexual intercourse until treatment is completed and symptoms resolve, typically about a week after finishing medication. Consulting a healthcare provider is important for personalized guidance. They can interpret test results, discuss individual circumstances, and recommend the appropriate course of action.