Early syphilis affects markers of HIV infection

Abstract

The objective of this study was to investigate if early syphilis infection affects markers of HIV infection; CD4 T cells and viral load (VL). A retrospective study was performed on 160 HIV-positive patients (111 receiving antiretroviral therapy [ART] and 49 without ART). Early syphilis diagnosis was made in HIV patients during their follow-up at the HIV/AIDS Unit at a Greek Dermatology and Venereology Unit. The patients’ blood tests were available at the time of diagnosis, as well as before and 12 weeks after early syphilis diagnosis. CD4 T cell counts and VL levels were measured. It was found that syphilis infection had a negative impact on the CD4 T cell counts in both groups, with reduced CD4 T cell counts observed in 84.6% (99/111) and 79.5% (39/49) of patients receiving and not receiving ART, respectively. After treatment for syphilis, CD4 T cell counts returned to pre-treatment levels in most patients, especially those receiving ART. There was a slight and transient VL increase. Patients receiving ART had a 27% increase in VL, compared to 71.4% among patients not receiving ART. Although the VL increase was slight (41–14,000 copies/ml) in the group under treatment, 4–5% (5/111) patients did not return to pre-treatment levels. Moreover, viral mutations associated with treatment resistance were identified in these patients. Early syphilis accelerates and complicates the progression of HIV infection. Early diagnosis and treatment of syphilis may prevent infection-associated complications in most instances. Consequently, prevention of syphilis and other sexually transmitted infections is of great importance for patients infected with HIV.

Keywords

Early syphilis HIV AIDS sexually transmitted infection men who have sex with men MSM CD4 T cells viral load antiretroviral therapy

Introduction

The prevalence of HIV and syphilis is increasing in similar patient populations (men who have sex with men, MSM), and coinfection is common.¹ The interaction of these infections is a complex and important issue and remains a research challenge. The genital ulcers caused by syphilis can bleed easily, and when they come into contact with oral and rectal mucosa during sex, increase the infectiousness of and susceptibility to HIV (immunological impairment and infection susceptibility).² The effects of syphilis infection on markers of HIV infection have not yet been sufficiently clarified; the few studies on this issue in the medical literature have been contradictory about the severity of the impact of early syphilis on markers of HIV infection.^1,2

Our study aims to establish the effect of early syphilis on CD4 T cell count and HIV viral load (VL) in HIV-infected patients for the following reasons: first, because early syphilis presents with severe immune disorders; second, because it is easy to determine the time of occurrence of early syphilis.^1,2 On the other hand, latent syphilis does not present the above characteristics. This study focuses on a homogenous sample of HIV-infected MSM for whom we have detailed clinical information on their antiretroviral therapy (ART), which enabled us to determine if there is a differential effect between those who are taking ART and those who are not.

Increased syphilis incidence in many industrialised countries in the last decade is in marked contrast to the low levels that prevailed in previous years.³ This increase is a consequence of a resurgence of high-risk behaviours, mostly among MSM many of whom are HIV-positive.^3–6 High rates of HIV coinfection among men with syphilis suggest HIV transmission is due to biological and behavioural risk synergy. The long survival of the infected patients, due to modern and improved treatment options offered by highly active antiretroviral treatment (HAART), has also contributed to this resurgence.

Objectives

This study investigated the impact of early syphilis on standard laboratory parameters that determine the course of HIV infection; namely CD4 T cell lymphocyte levels and VL in the blood of patients with HIV. These indicators were analysed before, during and after treatment of early syphilis.

Patients and methods

This retrospective study investigated and analysed the laboratory results of all patients with HIV infection coinfected with early syphilis supervised by the department of special infections at HIV/AIDS Unit of ‘A. Syngros’ Hospital of Dermatology and Venereology, Athens, Greece, over a period of 12 years from early 2002 to the end of 2013. A total of 160 patients were coinfected with HIV and early syphilis. Of these patients, 111 were receiving ART, whilst the remaining 49 did not. All the patients who were receiving ART had a consistently non-detectable VL for more than 12 months. The HIV patients who were not receiving treatment were under surveillance in the department for more than 12 months. All the participants of our study were established, long-standing HIV-infected patients.

Early syphilis in patients with HIV was diagnosed by the following methods, approved and recommended by the Centers for Disease Control and Prevention (CDC) and the International Union against Sexually Transmitted Infections (IUSTI)^7,8:

Syphilis diagnoses were confirmed in patients presenting with primary syphilitic chancre (40 patients) by dark field microscopy and serological tests (venereal disease research laboratory test [VDRL], enzyme immunoassay for immunoglobulin G and immunoglobulin M reactivity [EIA IgG and IgM], and T. pallidum particle agglutination test [TPPA]).

Cases with clinical suspicion of secondary syphilis (104 patients) were confirmed by serological tests (VDRL, EIA [IgG and IgM] reactivity and TPPA).

Early latent syphilis cases, defined as asymptomatic for syphilis were included in this study (16 patients) and were confirmed by positive EIA and TPPA, with or without positive VDRL, and previous negative serology test for syphilis in the previous year. Those tests were part of the regular sexually transmitted infection (STI) screening in patients with HIV infection. These patients underwent additional serological tests for syphilis due to reported high-risk sexual contact.

After confirmation of the early syphilis diagnosis ± CD4 T cell counts and VL were evaluated prior to syphilis coinfection (12 weeks) and after infection; i.e., up to 12 weeks after administration of appropriate treatment (with a standard deviation ± 4 weeks). All patients included in this study were treated with a single dose of benzathine penicillin G, 2.4 million units intramuscularly.⁹ Patients who were treated with doxycycline or those who developed neurological symptoms were excluded from the study.

All analyses were performed using Friedman’s non-parametric test. P values < 0.05 were considered significant. The comparison of the two groups was performed using the Wilcoxon signed-rank test. The statistical programme used for the analysis of our study was IBM SPSS Statistics 22 for Windows.

The study was performed in compliance with ‘A. Syngros’ Hospital’s Institutional Review Board appropriate policies related to the use of animal and/or human subjects and human-derived material.

Results

Patient characteristics

All patients included in this study were MSM. None of these patients were injecting drug users or had a history of mental illness. All patients on ART were compliant. The compliance was determined by patient’s blood test results (stable VL), monthly report from hospital’s pharmacy, pill count, provider documentation and monthly interviews with our patients. The duration of HIV of patients on ART was 10.9 ± 5.6 years, with a median of 11 years. On the other hand, the duration of HIV of patients not receiving ART was 6.9 ± 4.9 years, with a median of six years. The difference was statistically different between groups. The mean age of the 160 patients with HIV and early syphilis coinfections was 38.6 ± 7.5 years (median: 37 years); the mean age of all HIV patients monitored by the HIV/AIDS Unit at ‘A. Syngros’ Hospital of Dermatology and Venereology during the same period was slightly higher, at 39.5 ± 11.4 years (median: 39 years). A total of 61.8% (99/160) were ‘disease repeaters’ with a history of previous syphilis infection episodes.

The time of evaluation of CD4 T cells and VL prior to coinfection with syphilis was 9.3 ± 1.9 weeks, with a median value of 10 weeks (5–12 weeks). The mean duration between the diagnosis of syphilis and the measurement of CD4 cell and HIV VL was 1.9 ± 1 weeks with a median of two weeks. After coinfection, the mean time since the diagnosis of early syphilis was 10.1 ± 1.4 weeks, with a median of 10 weeks (7–12 weeks). Patients who did not have blood tests for CD4 T cells and VL in the last 12 weeks before early syphilis infection were excluded from the study.

Comparison of CD4 lymphocyte levels during early syphilis according to HIV treatment

During early syphilis, CD4 T cell lymphocyte counts decreased in 94 of 111 patients treated with ART (84.6%) and in 39 patients not receiving ART (79.5%). Early syphilis tended towards a negative impact on CD4 T cell levels, but the difference between groups was not statistically significant (P = 0.49).

Comparison of VL during early syphilis following HIV treatment

Syphilis had a statistically significant effect on VL (P = <0.0001) among patients receiving ART compared to those who were not. Specifically, 27% (30/111) of patients receiving ART and 71.4% (35/49) of patients without showed increased VL.

Comparison of CD4 T cells levels before, during and after early syphilis diagnosis

Patients receiving ART had substantially reduced CD4 T cell levels at the time of early syphilis diagnosis compared to pre-coinfection levels. Among patients receiving ART, the median CD4 T cell count was 637 ± 484 (interquartile range) before syphilis infection, decreased to 534 ± 343 during infection, and returned to 680 ± 394 after treatment. Friedman’s test showed a statistically significant difference in CD4 T cell count (P < 0.001). Post hoc analysis showed statistically significant differences between the CD4 T cell count before and during syphilis (P < 0.001) and between the CD4 T cell count during syphilis and after treatment (P < 0.001).

The same phenomenon was observed in patients not receiving ART. In patients not receiving ART, the median CD4 T cells count was 604 ± 235 before coinfection, 451 ± 222 during early syphilis and 495 ± 260 after treatment. Friedman’s test showed a statistically significant difference in CD4 T cell count (P < 0.001). Post hoc analysis showed statistically significant differences between the CD4 T cell count during syphilis and after treatment (P < 0.001) and between the CD4 T cell count before syphilis and after treatment (P < 0.001), suggesting poor immune recovery after resolution of syphilis infections (Figure 1 and Table 1). CD4 T cells levels among patients without ART did not return to pre-coinfection levels, but instead of that we noticed a slight increase after early syphilis treatment. In addition, six patients not receiving ART presented with further CD4 T cell reduction during the scheduled follow-up 12 weeks after syphilis treatment, which led to initiation of ART (due to CD4 T cell levels < 350).

Figure 1.

Median CD4 cell counts (blue line: people with ART, blue diamond: IQR for people with ART, red line: people without ART, red circles: IQR for people with ART).

Table 1.

Comparison of CD4 T cell levels before, during and after early syphilis diagnosis.

	CD4 T cells before syphilis	CD4 T cells during syphilis	CD4 T cells after treatment of syphilis	Overall comparison	Before versus during syphilis	During versus after syphilis	Before versus after syphilis
Patients under ART	637 ± 484	534 ± 343	680 ± 394	P < 0.001	P < 0.001	P < 0.001	Ns
Patients without ART	604 ± 235	451 ± 222	495 ± 260	P < 0.001	Ns	P < 0.001	P < 0.001

Comparison of VL before, during and after early syphilis diagnosis

VL in patients receiving HIV treatment increased above the detection limit (20 copies/ml) during the course of syphilis infection in 30 of 111 patients. This increase was generally small. There was also a slight increase in VL during early syphilis among patients not receiving ART, which subsided after syphilis treatment. Increased VL was observed in 35 of 49 patients. However, when this increase was expressed in copies/ml, there were no statistically significant differences before, during and after treatment for early syphilis. In summary, among patients receiving ART, the median VL was 0 ± 0 (0 means undetectable VL, i.e. VL < 20 copies/ml) before syphilis infection, it decreased to 0 ± 74 during infection and retuned to 0 ± 0 after treatment. Friedman’s test showed a statistically significant difference in VL (P < 0.001). Post hoc analysis showed statistically significant differences between the VL before and during syphilis (P = 0.015). In patients not receiving ART, the median VL was 7500 ± 25,150 before coinfection, 17,000 ± 39,750 during early syphilis and 11,500 ± 20,675 after treatment. Friedman’s test showed no statistically significant difference in VL (Table 2).

Table 2.

Comparison of VL before, during and after early syphilis diagnosis.

	VL before syphilis	VL during syphilis	VL after treatment of syphilis	Overall comparison	Before versus during syphilis	During versus after syphilis	Before versus after syphilis
Patients under ART	0 ± 0	0 ± 74	0 ± 0	P < 0.001	P = 0.015	Ns	Ns
Patients without ART	7400 ± 22,900	17,000 ± 39,300	11,000 ± 20,000	Ns	Ns	Ns	Ns

Note: VL, viral load.

After syphilis treatment, VL fell below detectable levels in all but five patients undergoing ART (4.5%). Genotypic testing of viruses from these five patients showed development of resistance mutations that required changes in ART regimens (Table 3). The average VL difference among patients on ART was −7 ± 25 (P = 0.79, 95% confidence interval [CI] = −43.7–57.3) before and after coinfection and 295 ± 152 (P = 0.05, 95% CI = −593.5–3.3) during and after coinfection.

Table 3.

VL, HAART and resistance mutations after syphilis coinfection.

	VL before syphilis	VL during syphilis	VL after treatment of syphilis	Treatment before syphilis	Mutations
Patient 1	<20	2640	1100	FTC/TDF/NVP	K103N
Patient 2	<20	14,000	2100	AZT/3TC/NVP	M184V, T215Y, M41L
Patient 3	<20	7600	1300	AZT/3TC/NVP	Μ184 V, V75T, V118I
Patient 4	<20	3200	1700	AZT/3TC/FPV/r	M184V
Patient 5	<20	950	700	3TC/ddI/EFV	M184V, E138A

Note: VL, viral load; HAART, highly active antiretroviral therapy; FTC, emtricitabine; TDF, tenofovir; NVP, nevirapine; AZT, zidovudine; 3TC, lamivudine; FPV, fosamprenavir; r, ritonavir; ddI, didanosine; EFV, efavirenz.

Discussion

In the last decade, patients with HIV infection have had an increased incidence of not only early syphilis but also other STIs, primarily due to a resurgence of high-risk sexual behaviours.^10–12 A long-term study conducted among US military personnel found that 5.8% of 4239 newly diagnosed HIV infections also had serological evidence of syphilis infection.¹³ Increased prevalence of syphilis–HIV coinfections in young MSM was also reported in other regions of the world.^14–17

Whilst HIV is known to affect the course of syphilis, early syphilis also affects markers of HIV infection.^18–20 Many studies suggest that diseases that cause genital ulcers, such as syphilis, may be responsible for ‘gateway’ entry of HIV.^15–24 The general characteristics of the patients of this study confirm the current data in the medical literature, as all HIV patients included in this study were young, male, MSM, with continued high-risk sexual behaviours. All our patients complied with ART, as indicated above. The findings of our study may be attributed to biological or immunological effects of syphilitic infection on HIV disease. Maybe there are some more explanations for our results such as unmeasured variables, race, behavioural characteristics, stage of syphilis, etc. All these factors were not measured and may be important to conduct a more comprehensive conclusion. The high percentage (68%) of patients in the study who were reinfected with syphilis (disease repeaters) confirms that these patients undertook risky sexual practices.^2,10–13,25 The occurrence of early syphilis in patients with HIV is an indicator of high-risk sexual behaviours, which can increase the probability of HIV transmission.

There is a controversy about the effect of syphilis on HIV infection; some studies consider this effect as great, whilst others as of minor importance.^6,13,14 Previous studies have revealed that the diagnosis of early syphilis in HIV patients does not affect the progression of HIV disease, in terms of AIDS and death as end points.²⁶ These inconsistent findings may be due to the small numbers of patients presenting with coinfections, short-term patient monitoring and lack of evaluation between the stage of syphilis and levels of CD4 T cells and VL. The findings of the present study showed that the number of CD4 T cells was negatively affected during early syphilis in the majority of HIV patients, regardless of drug treatment. After syphilis treatment, the number of CD4 T cells in patients on ART increased again. In most cases, CD4 T cell counts returned to values similar to those presented before coinfection with syphilis. CD4 T cell levels after early syphilis treatment improved slightly compared to levels at diagnosis in patients who were not receiving ART, but did not return to previous levels; the difference before and after syphilis treatment remained statistically significant. In addition, six patients not receiving ART presented with further CD4 T cell reduction during the scheduled follow-up 12 weeks after syphilis treatment, which led to initiation of ART (due to CD4 T cell levels < 350). These findings are concordant with other reports.^6,27,28

Patients in this study had a slight and transient increase in VL. However, there was a significant difference in the proportion of VL increase among patients under ART compared with those not receiving ART. Specifically, 27% of patients receiving ART and 71.4% of patients without ART presented with increased VL. ART was obviously protective for most patients and prevented resurgence of viral replication during syphilitic infection. Patients under ART returned to their pre-coinfection immunological levels. Patients not receiving ART also showed slightly increased VL during the course of syphilis infection that subsided after successful treatment. The few studies in the medical literature that analyse the effect of syphilis treatment on VL report contradictory findings. Kofoed et al.²⁹ had similar results to our study, concluding that indicators of HIV infection usually resolve after syphilis treatment, whilst Palacios et al.³⁰ found increased VL in the majority of patients with HIV not receiving ART. Conversely, Sadiq et al.³¹ found no correlation between VL or CD4 T cell count or ART status and early syphilis. In addition, in our study among the group of young men coinfected with HIV and early syphilis, many had detectable VLs collected near the time of syphilis diagnosis, suggesting the risk of HIV transmission. The same applies to the study of Centers for Disease Control and Prevention¹⁵ and Taylor et al.³² Some researchers suggest the immediate initiation of ART in seropositive MSM with syphilis coinfection and high VL, in order to reduce the chances of HIV transmission.³³

Genotypic testing of samples from the five patients receiving ART and who experienced increased VL after syphilis treatment in this study revealed development of viral mutations that conferred resistance to antiretroviral drugs. Those five patients who developed resistance were compliant to the treatment and they never had identifiable VL previous to syphilis infection. The VL was increased during early syphilis infection and it did not decrease to pre-infection levels. Treatment failures required changes in antiretroviral regimens in about 4.5% (5/111) of patients in our study.

The limitations of this study include the absence of a control arm, the study performance in a single site and the lack of a multivariate model and long-term follow-up. There were also factors (immune mechanisms, social factors, types and methods of suspected sexual intercourses etc.) that were not measured and may be important. Moreover, the analysis of the study was not based on a stratification model as it is not always possible to identify the stages of early syphilis (primary, secondary, early latent). In many cases, the clinical manifestations of primary syphilis (chancre) may coexist with those in the secondary stage (papulopustular rash).

In conclusion, the effect of early syphilis on CD4 lymphocyte levels and VL is usually mild, transient and reversible with treatment.^34,35 However, (a) early diagnosis and treatment of syphilis is important. The substantial risk of syphilis and HIV infection in men diagnosed with one of these STIs indicates a high frequency of unsafe sex in the MSM population of Greece and other countries.³³ The long-term effects of untreated syphilis during HIV infection are unknown, but patients with HIV may develop severe syphilitic lesions and more often develop neurosyphilis.^36,37 (b) Treatment of early syphilis did not lead to CD4 T cell recovery in all cases. Five patients receiving ART developed resistance that required changes in ART, whilst a significant CD4 T cell reduction in six untreated patients led to initiation of ART. Therefore, avoiding syphilis exposure may be essential for patients with HIV, in addition to early referral for suspicious symptoms or risky sexual contacts. Finally, it is important to underline the need for frequent, routine screening for syphilis in those infected with HIV or at risk of HIV in order to avoid coinfection and resultant complications. Thus, routine screening for syphilis in asymptomatic HIV-infected patients should be performed not only at the time of HIV diagnosis but also during follow-up for these patients.³⁸

Footnotes

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

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