Syphilis Syphilis Epidemiology. Part I

Syphilis Epidemiology Thad Zajdowicz, MD, MPH Medical Director, STD/HIV Program Chicago Dept of Public Health Why a lecture on syphilis? Although syphilis is an eminently treatable disease, its continuing occurrence illustrates that our control efforts still need to be improved. The disease remains elusive clinically even today, and unless thought of and sought for can silently cause disease as it has for centuries. Further, control of syphilis is vital because of its interactions with HIV. This lecture will focus on syphilis epidemiology; following lectures will explore the clinical manifestations of this most protean of diseases. Objectives • To understand the prior and current impact of syphilis • To define current trends of syphilis in the U.S. • To understand how syphilis and HIV interact Etiology and Course Syphilis is a chronic, systemic infection caused by a spirochete, Treponema pallidum. The primary mode of transmission is via sexual contact. Untreated, syphilis progresses through a primary and secondary stage before becoming latent. Up to 1/3 of people with untreated syphilis develop tertiary disease late in life, primarily cardiovascular and neurologic. Syphilis is also transmitted congenitally from an infected mother to her infant. Historical Issues • Emergence of syphilis in Europe in 1490s • ? Imported from the Americas (Columbian theory) or ? Emergence in Europe from other treponematoses • Severe disease (called The Great Pox to distinguish it from smallpox) Pre-Penicillin Era • Highly prevalent in many countries/societies in pre-penicillin era • Estimates of 10% of U.S. population infected in early 20th Century – Higher rates in socially disadvantaged populations, e.g. rural African-Americans in the South • Dramatic drop in incidence/prevalence after introduction of penicillin in mid1940s Syphilis Worldwide • WHO estimates 12 million new cases of syphilis worldwide (http://www.who.int/docstore/hiv/ GRSTI/pdf/figure09.pdf) • Greatest burden in adolescents and young adults • Greatest numbers of new cases in South and Southeast Asia, followed by sub-Saharan Africa Syphilis in the U.S. http://www.cdc.gov/std/stats/2002pdf/Syphilis.pdf Current U.S. Syphilis Epidemiology • Rates of primary and secondary (P&S) syphilis declined every year from 1990-2000 • In 2001, rates of P&S syphilis began rising again – However, rise in new cases is seen in men who have sex with men (MSM) – Male:female ratio of cases rose from ~ 1:1 to ~3.5:1 in past 8 years Primary and Secondary Syphilis --- United States, 2002 P&S Syphilis Cases by Region 3500 3000 2500 2000 1500 1000 500 0 2001 2002 Northeast Midwest South West Primary and Secondary Syphilis --- United States, 2002 Race & Ethnicity • In 2001-2002, P&S syphilis rates increased 71.4% among non-Hispanic white men and 28.6% among Hispanic men – No changes in rates in females of same groups • Among non-Hispanic blacks, P&S syphilis rates decreased 10.9% – 2.2% for men, 22.6% for women • There were significant rate changes in both Asian/Pacific Islanders and American Indians/Alaska Natives – However, very few cases in both groups overall No. Reported Cases 10 15 20 25 30 0 Jan Feb M ar A pr M ay June Jul y A ug Sept Oct Nov De c Jan Feb M ar A pr M ay June Jul y A ug Sept Oct Nov De c Jan Feb M ar A pr M ay June Jul y 5 P&S Syphilis among MSM, Chicago, 2000-2002 by Month of Treatment 2000 Month CP 2001 2002 P&S Syphilis , by Gender and Sexual Orientation, 1998-2003*, Chicago Females 23 109 12 112 MSM Heterosexual Males 15 103 14 64 Male-unk 46 53 9 29 Number Cases 48 282 42 45 178 211 106 158 116 129 61 43 2002 N=353 17 2003 N=161 1998 N=338 1999 N=282 2000 N=292 2001 N=317 Congenital Syphilis • Syphilis is transmissible from mother to infant • Transmission usually occurs during early stages, but may occur at any stage in an untreated mother • Incidence of infection rose in U.S. in late 1980s-early 1990s with rise in heterosexual cases Congenital Syphilis • Rates of congenital syphilis in U.S. continue to decline as new cases of P&S syphilis decline in heterosexuals • http://www.cdc.gov/std/stats/tablessyph. htm • http://www.cdc.gov/epo/mmwr/preview/ mmwrhtml/mm4834a3.htm Epidemiological Synergy • HIV and syphilis co-facilitate transmission of each other • Biological plausible because: – STDs facilitate HIV shedding – Cellular recruitment of HIV susceptible cells occurs – Mucosal barriers are breached – Immunosuppression Behavioral Risk • Behaviors that are risky for transmission of syphilis are also risky for transmission of HIV • This has been demonstrated in studies in various areas of the world • http://www.pubmedcentral.gov/articl erender.fcgi?tool=gateway&pubmedid =14585109 Sources of Information The following sites are useful if more information on syphilis epidemiology is sought: www.cdc.gov Centers for Disease Control www.who.int World Health Organization www.ashastd.org American Social Hygiene Assoc www.vnh.org Virtual Naval Hospital