Researchers have found that cases of ocular syphilis have been increasing in North Carolina and that the prevalence of ocular syphilis was almost twice as high among HIV-positive patients as among those who were HIV negative or HIV unknown.
The number of patients with ocular syphilis (OS) is increasing, and OS may be more common in syphilis patients who have concurrent HIV than in those who don't, recent research from North Carolina suggests.
"Reports of primary, secondary, and early latent syphilis have increased in North Carolina in recent years. Between 2014 and 2015, early syphilis increased from 1137 cases to almost 1900 cases, representing a 64% increase in reported cases... We found ocular syphilis in all stages of syphilis," lead author Anna Barry Cope, PhD, MPH, said in her late-breaker presentation September 22, 2016 at the Centers for Disease Control and Prevention (CDC) 2016 STD Prevention Conference in Atlanta, Georgia.
"Nearly half of all syphilis cases in North Carolina are co-infected with HIV. They were infected with HIV either prior to their syphilis diagnosis or within 30 days after," added Dr. Cope, an epidemiologist at CDC in Atlanta.
"Clinicians need to look for ocular syphilis in their at-risk patients. Patients need to know whether they have ocular syphilis, and that if they have it, they need to get treated quickly to prevent complications, including possible blindness," Thomas Peterman, MD, MSc, chief of the Field Epidemiology Unit for the Epidemiology and Surveillance Branch of the Division of STD Prevention at CDC in Atlanta, who moderated the late-breaker session, told Contagion®.
Dr. Cope and her colleagues compared OS prevalence by HIV status and timing of HIV diagnosis among all syphilis patients in North Carolina. They reviewed all syphilis cases reported in the North Carolina Electronic Disease Surveillance System (NC EDSS) in 2014 and 2015.
The researchers identified potential ocular syphilis cases in NC EDSS and matched ocular and non-ocular syphilis cases with the Enhanced HIV/AIDS Reporting System (eHARS) to obtain HIV diagnosis date.
They grouped all syphilis cases with HIV co-infection into previously diagnosed (HIV diagnosed more than 30 days before syphilis diagnosis) and concurrently diagnosed (HIV diagnosed within 30 days before or after syphilis diagnosis) cases. Cases with HIV diagnosed more than 30 days after syphilis diagnosis were considered HIV-uninfected. Prevalence ratios were used to match OS prevalence with HIV status.
Of 4232 confirmed syphilis cases, 63 (1.5%) had ocular syphilis; of these 63 cases, 35 (56%) were co-infected with HIV; and of the 35, the diagnosis was concurrent in 11 cases (31%).
Of the 4169 confirmed syphilis cases without OS, 1659 (40%) were co-infected with HIV; of the 1,659, the diagnosis was concurrent in 253 (15%).
The prevalence of ocular syphilis was almost twice as high among HIV-positive patients as among those who were HIV negative or HIV unknown (prevalence ratio 1.9; 95% confidence interval, 1.1 to 3.1).
Of the 1694 HIV-infected syphilis cases, 264 were diagnosed with HIV at the same time as their syphilis diagnosis, and 4.2% of the 264 cases were classified as ocular syphilis cases (prevalence ratio 2.5; 1.2 to 5.0).
Among syphilis patients with a previous HIV infection, those with OS were older than those without OS (median age 42 years vs 33 years; P=.008), and they had a lower CD4 cell count (median 384 cells vs 521 cells/mL; P=.03). The viral load was roughly equal between OS and non-OS patients (median 40 copies vs 20 copies/ml, P=.4).
Syphilis patients concurrently diagnosed with HIV who had OS were also older than those without OS (median age 48 years versus 27 years; P=.0004) and had a lower CD4 cell count (260 cells vs 382 cells/mL; P=.04). Patients with OS had a higher viral load (median 65,780 copies versus 44,024 copies/ml, P=.08)
In March 2016, the CDC issued a clinical advisory to US clinicians urging them to be aware of ocular syphilis, screen for visual complaints in patients at risk for syphilis, and test all patients with syphilis for HIV if their status is unknown or has been negative.
"The associations we found between older age, lower CD4 counts, and the prevalence of ocular syphilis suggests that OS development may be affected by immune status," Dr. Cope said in an interview.
"All syphilis patients, especially those with ocular syphilis, should be screened for HIV," she noted.
Drs. Cope and Peterman called for further related research.
Lorraine L. Janeczko, MPH, is a medical science writer who creates news, continuing medical education and feature content in a wide range of specialties for clinicians, researchers and other readers. She has completed a Master of Public Health degree through the Department of Epidemiology of the Johns Hopkins Bloomberg School of Public Health and a Dana Postdoctoral Fellowship in Preventive Public Health Ophthalmology from the Wilmer Eye Institute, the Johns Hopkins University School of Medicine and the Bloomberg School.
DISCLOSURES: The authors of both studies and Dr. Peterman did not report any conflicts of interest with the studies.