Abstract
Background
Rates of syphilis in the U.S. have more than doubled over the last several decades, largely among men who have sex with men (MSM). Our study characterizes a cluster of neurosyphilis cases among HIV-1-infected individuals in Vermont in 2017-2018.
Methods
Vermont Department of Health disease intervention specialists conduct interviews with all newly diagnosed HIV-1 cases and pursued sexual networking analyses. Phylogenetic and network analyses of available Vermont HIV-1 polymerase (pol) sequences identified clusters of infection. Fishers-exact and independent t-tests were used to compare HIV-1-infected individuals within or outside an identified cluster.
Results
Between January 1, 2017 and December 31, 2018, 38 Vermont residents were newly diagnosed with HIV-1 infection. The mean age was 35.5 years, 79% were male and 82% were white. Risk factors for HIV-1 acquisition included MSM status (79%) and methamphetamine use (21%). Eighteen cases (49%) had HIV-1 viral loads (VLs) >100,000 copies/mL and 47% had CD4 cell counts <200/mm 3. Eleven of the 38 (29%) cases had positive syphilis serology, including four (36%) with neurosyphilis. Sexual networking analysis revealed a ten-person cluster with higher VLs at diagnosis (90% with VLs > 100,000 copies/mL vs. 33%, p=0.015). Phylogenetic analysis of pol sequences showed a cluster of 14 cases with sequences that shared 98-100% HIV-1 nucleotide identity.
Conclusions
This investigation of newly infected HIV-1 cases in Vermont led to identification of a cluster that appeared more likely to have advanced HIV-1 disease and neurosyphilis. Identification of a cluster was strongly supported by both phylogenetic and network analyses of HIV-1 pol sequences.
The Relationship of Preventable Opportunistic Infections, HIV-1 RNA, and CD4 Cell Counts to Chronic Mortality
