Sexually transmitted infections (STI)
Sexually transmitted infections (STIs) are infections that can pass from one person to another during oral, vaginal or anal sex without a condom, and many cause no symptoms. At Laboratorio Aclimu we run the tests to detect them confidentially and with clear results. Getting tested early lets you take care of yourself and your partner, and start treatment when needed.

What are STIs (sexually transmitted infections)?
STIs (sexually transmitted infections) are transmitted mainly during sex without a condom, through contact with semen, vaginal fluids or blood. Some can also be transmitted through blood (by sharing sharp or piercing objects) or from mother to baby during pregnancy, childbirth or breastfeeding. Having an STI does not make you immune: a person can be infected again, and all STIs can be treated.
The World Health Organization groups these infections into curable ones — such as syphilis, gonorrhea and chlamydia, which are treated with antibiotics — and viral ones, such as HIV, hepatitis B and C, herpes and HPV. Knowing your status is the first step to getting the right treatment.
The infections we test for
In our STI and serology area we cover the most common infections and, for each one, we use the most appropriate laboratory technique. A brief guide:
HIV — 4th-generation test
HIV can only be detected through a lab test: it is the only way to know whether a person has contracted the virus.
Our test is a 4th-generation test: it detects, at the same time, the p24 antigen (a viral protein that appears very early) and antibodies against HIV-1 and HIV-2. Looking for p24 in addition to antibodies makes it possible to identify the infection earlier than tests that only look for antibodies, shortening the so-called window period.
With 4th-generation tests (like the one we use), the detection window is approximately 18 days in most cases. To confirm a negative result, repeating the test at 6 weeks is recommended; 90 days is the conservative window set by the Ministerio de Salud (Argentina's national Ministry of Health) for a definitive rule-out. HIV testing is voluntary and confidential.
Syphilis
Caused by the bacterium Treponema pallidum, it is detected through a blood test that looks for antibodies.
We offer nontreponemal tests (VDRL or RPR), whose results are reported as titers, and confirmatory treponemal tests (FTA-ABS or TPHA), which are highly sensitive and specific.
Hepatitis B
It is transmitted through direct contact with infected blood, semen or vaginal discharge, as well as from mother to baby. There is a vaccine, included in the Calendario Nacional de Vacunación (Argentina's national immunization schedule).
Available tests: HBsAg (surface antigen, the initial test), anti-HBc (IgM suggests recent infection; IgG indicates past or chronic infection), anti-HBs (indicates immunity from vaccination or from a resolved infection) and HBV DNA viral load, which measures the amount of virus present in the blood.
Hepatitis C
It may cause no symptoms for years, which is why getting tested is important, especially when there are known risk factors.
Available tests: anti-HCV, which looks for antibodies produced by the immune system in response to the infection, and HCV RNA, which detects the virus's genetic material and measures the viral load.
Herpes simplex 1 and 2
The virus has an incubation period of 2 to 12 days, although this can vary.
When there is an active lesion, the most sensitive test is PCR of the lesion: it detects the virus's genetic material in a sample of fluid or tissue from the affected area. We also test for antibodies in the blood (IgG and IgM against HSV-1 and HSV-2) to assess previous exposure.
HPV (Human Papillomavirus)
We perform PCR with genotyping, which makes it possible to identify high-risk genotypes, especially 16 and 18, which are linked to the development of cancer of the cervix, anus, oropharynx and other sites. Genotyping is key for follow-up: knowing which genotype the patient has allows the doctor to decide how often check-ups are needed and to assess whether the infection persists or clears over time.
More than 200 HPV genotypes are known; at least 14 are considered high oncogenic (cancer-causing) risk. Our test identifies each of them individually, providing precise information for clinical management.
Gonorrhea, Chlamydia, Mycoplasma and Ureaplasma
These are bacterial infections that we detect by PCR (Neisseria gonorrhoeae, Mycoplasma genitalium, Chlamydia trachomatis) or by culture (Mycoplasma hominis, Ureaplasma urealyticum). All of them are curable with antibiotic treatment prescribed by a healthcare professional.
These tests require 72 hours of prior preparation, and samples are collected Monday through Friday. We'll give you the details when you book your appointment.
Mpox (monkeypox)
Caused by the mpox virus (Monkeypox virus, MPXV — genus Orthopoxvirus, family Poxviridae), it is transmitted through direct contact with skin lesions or rashes, including kissing, intimate contact and sex.
Diagnosis is by qPCR from a vigorous swab of the lesion or of the surface scabs. No blood draw or prior preparation is needed, and results are available within 48 business hours.
Symptoms and when to get tested
Many STIs cause no symptoms, discomfort or visible lesions, so a person can have them and pass them on without knowing it. When signs do appear, the most common are: discharge or secretions that are different from usual, sores or lesions on the genitals, warts, burning when urinating, or pain in the lower abdomen or during sex.
Testing shouldn't wait until there are symptoms. It's a good idea to get tested after sex without a condom, when starting a relationship with a new partner, if a partner has tested positive, or regularly as part of looking after your sexual health.
If you have symptoms such as lesions, sores or discharge, come in and get tested without waiting: in these cases, the tests that directly detect the infectious agent (PCR for herpes, HPV, gonorrhea, chlamydia, Mycoplasma, Ureaplasma or Mpox) are done on a sample taken from the lesion or the affected area.
Window period: when the result is reliable
The window period is the time between when the pathogen (virus or bacterium) enters the body and when the infection can be detected by a test. During that stage, a test can come back negative even though the infection is present.
For HIV with 4th-generation tests (the ones we use), the window is approximately 18 days; it's advisable to repeat the test at 6 weeks to confirm a negative result (90 days for a definitive rule-out, according to the Ministry of Health guidelines). For syphilis, the window is 3 to 6 weeks; for hepatitis B and C, between 4 and 12 weeks. In all cases, after a high-risk exposure, repeating the test at 12 weeks is recommended for a definitive rule-out.
PCR tests (herpes, HPV, gonorrhea, chlamydia, Mycoplasma, Ureaplasma and Mpox) look for the genetic material of the infectious agent (virus or bacterium, depending on the case) in a sample from the affected area, and depend on there being an active infection at the sampling site.
Prevention and timely diagnosis
Using a condom correctly every time you have sex (oral, vaginal and anal) is the most effective way to prevent most STIs. Other tools add to this, such as the hepatitis B vaccine and the HPV vaccine, both included in Argentina's national immunization schedule.
Early diagnosis makes it possible to start treatment in time, avoid complications (such as infertility or transmission to the baby during pregnancy) and break the chain of transmission. Getting tested regularly, without stigma and as part of your routine health care, is the best way to stay protected.
At Aclimu you can get your STI tests done confidentially, with online appointments and no prescription needed for self-pay tests. We support you with professional, clear and stigma-free care.
Frequently asked questions
Do I need a prescription to get STI tests?
Not for self-pay tests: you can book an appointment online and have them done with no prescription needed. HIV testing is voluntary and no one can be forced to take it. If you want your health insurance (obra social or prepaid plan) to cover the test, you will need a prescription from your doctor.
Is it confidential?
Yes. Results are confidential: the healthcare team cannot disclose which test was done or the diagnosis, and you decide who to share them with.
What is a 4th-generation HIV test and why does it matter?
4th-generation tests detect, at the same time, the p24 antigen (a viral protein that appears very early) and antibodies against HIV-1 and HIV-2. Looking for the antigen in addition to antibodies makes it possible to identify the infection earlier than tests that only look for antibodies, which shortens the window period. According to Argentina's Ministry of Health, this period is up to one month in most cases, and repeating the test at 90 days is recommended to confirm.
When should I get tested after an exposure?
For HIV with a 4th-generation test, the detection window is approximately 18 days; repeating the test at 6 weeks is recommended (or at 90 days for a definitive rule-out, according to the Ministry of Health guidelines). For syphilis, 3 to 6 weeks; for hepatitis B and C, 4 to 12 weeks, with retesting at 12 weeks if suspicion is high. If you have symptoms or a lesion, don't wait: come in to get tested and see a healthcare professional.
How long do results take?
It depends on the test. Most serology tests (HIV, syphilis, hepatitis) are ready within a few business days. For Mpox by PCR, results are usually ready within 48 business hours after the sample is collected. When you book your appointment, we'll tell you the turnaround time for each test.
Sources
- Office for the Response to HIV, STIs, Viral Hepatitis and Tuberculosis (in Spanish) — Ministry of Health, Argentina
- Sexually transmitted infections (STIs) (in Spanish) — Ministry of Health, Argentina
- How to find out if you have HIV (in Spanish) — Ministry of Health, Argentina
- Viral hepatitis (in Spanish) — Ministry of Health, Argentina
- HIV and syphilis testing and testing centers (in Spanish) — Buenos Aires City Government
- Sexually transmitted infections (STIs) — World Health Organization (WHO)
- Four curable sexually transmitted infections: all you need to know — World Health Organization (WHO)
- Mpox (monkeypox) — World Health Organization (WHO)
The information on this page is for guidance only and does not replace a consultation with a healthcare professional.
