Infection with syphilis causes temporary rebound in HIV - case report

Michael Carter
Estimated reading time 2 minutes
This article is more than 21 years old.

Immune activation caused by infection with syphilis can stimulate latent reservoirs of HIV and cause viral load to rebound to low levels, according to a case report published in the September 26th edition of AIDS. Syphilis should be considered as a cause of low-level rebound in patients with previously undetectable viral load, say the investigators.

The case concerned a 28 year old gay men who had had maintained an undetectable viral load for 18 months after starting HAART. However, low level HIV viral load (ranging from 64 copies/mL to 741 copies/mL) was detected on three instances at four weekly intervals in the summer of 2001. Without a change in HIV treatment regimen the man’s viral load then became undetectable again and has remained so for 17 months.

Coinciding with the low rebound in viral load, the patient reported low-grade fevers after several unprotected casual sexual contacts. Syphilis was diagnosed and the man received appropriate antibiotic therapy.

Glossary

syphilis

A sexually transmitted infection caused by the bacterium Treponema pallidum. Transmission can occur by direct contact with a syphilis sore during vaginal, anal, or oral sex. Sores may be found around the penis, vagina, or anus, or in the rectum, on the lips, or in the mouth, but syphilis is often asymptomatic. It can spread from an infected mother to her unborn baby.

deoxyribonucleic acid (DNA)

The material in the nucleus of a cell where genetic information is stored.

viral rebound

When a person on antiretroviral therapy (ART) has persistent, detectable levels of HIV in the blood after a period of undetectable levels. Causes of viral rebound can include drug resistance, poor adherence to an HIV treatment regimen or interrupting treatment.

reverse transcriptase

A retroviral enzyme which converts genetic material from RNA into DNA, an essential step in the lifecycle of HIV. Several classes of anti-HIV drugs interfere with this stage of HIV’s life cycle: nucleoside reverse transcriptase inhibitors and nucleotide reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs). 

proviral DNA

The chemical form in which HIV's genetic information is stored within infected cells.

The patient’s recent sexual history led the investigators to speculate that the man had been superinfected with another strain of HIV, causing his viral load to rebound. However, tests conclusively revealed that the virus the man was initially infected with was the same as that detected during the man’s viral rebound.

Attention then shifted to resistance as a possible cause of the viral rebound. Clonal sequencing of the protease and reverse transcriptase regions were performed, but no resistance-conferring mutations in either region were detected.

Having ruled out these two possibilities, levels of proviral HIV DNA were measured in peripheral blood mononuclear cells. Levels of proviral DNA fell sharply during the period of the patient’s low-level rebound.

The investigators concluded that the man’s short-term, low-level rebound may have originated from activated reservoirs of previously infected cells, with the activation caused by infection with syphilis.

”This observation” conclude the investigators, “suggests that efforts should be made to study apparent causes of virological failure carefully before a particular regimen is abandoned.”

Further information on this website

Syphilis - overview

Syphilis - factsheet

References

Padte N et al. Sustained viremia during highly active antiretroviral therapy with accelerated proviral DNA decay in the setting of infection with syphilis. AIDS 17: 2143 – 2145, 2003.

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