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23 Cards in this Set
- Front
- Back
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How can you categorize STDs?
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Excluding HIV, HBV, HPV, we can classify STDs into 2 main groups:
Discharge - Urethral/Vaginal Gonorrhoea, Chlamydia, Candida, Trichomonas vaginalis, Bacterial Vaginosis Genital Ulcer Syphilis, Chancroid, Donovanosis, Herpes simplex and Lymphogranuloma venereum |
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Global incidence of STIs (WHO)
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Syphilis - 12 million
Chlamydia - 92 million Gonorrhea - 62 million Trichomoniasis - 174 million Global total - 340 million *trich has highest incidence, but CT is always listed as highest bc trich is not reportable |
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Why Increasing rates of STDs?
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Difficult to change behavior
Taboo topic in many situations Mobility of populations (migrant groups) No vaccines yet for any of them No durable natural immunity after infection Inadequate treatment & other healthcare Economic aspects |
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STDs - Special Problems
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STDs in women
Antibtiotic resistance -Gono, H. ducreyi Core group concept Even when Ro = <1, an STD can be maintained by the existence of a core group. Mathematical modeling used to predict impact and cost-effectiveness of control strategies Ro- # people who can be infected by one person, want <1 |
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STDs in Women
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STDs may be asymptomatic, esp. in women and these persons can be sources
Sequelae of STDs tend to more severe and frequent in women |
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STDs in Women - what are the Sequelae of STDs
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Sequelae of STDs tend to more severe and frequent in women
Spread (Gonococci, Chlamydia) into the uterus and fallopian tubes can cause PID and may lead to infertility and ectopic pregnancy May be associated with cervical cancer - HPV Vertical transmission from mother to baby - some like gonorrhoea and chlamydia can be treated, but congenital syphilis results in death or deformed babies. |
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SYPHILIS epi
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Caused by Treponema pallidum
Sexual contact, congenital, transfusion, direct inoculation Systemic illness - almost all organs can be involved 12 m; slowly rising in developed countries too |
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Elimination of Syphilis?
How is Syphilis is biologically "vulnerable"? |
Syphilis is biologically "vulnerable":
Long incubation time No non-human host Treatment inexpensive No antibiotic resistance |
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Goals for Syphilis elimination
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In the U.S:
National level: Absence of sustained transmission State level: No new cases locally except within 90 days of imported case When translated to numerical goals: < 1,000 cases in U.S. > 90% of counties syphilis free |
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Gonorrhoea epi
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62 million cases worldwide
Caused by Neisseria gonorrhoeae Can cause severe disease in women Co-infection with Chlamydia Gonococcal ophthalmitis in newborn Diagnosed by bacterial culture Treated with antibiotics; drug resistance is a problem |
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Chlamydial infections epi
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Approx. 90 million cases worldwide
Causes NSU (NGU); Most common notifiable STD Incidence rising in developed nations Can be severe disease in women and children Treated with antibiotics; treat for gonorrhoea also. |
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Chlamydia - Diagnosis
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No gold standard
Combination of tests used as reference Culture is difficult, 100% specific, but not highly sensitive Nucleic acid based tests detect 20-30% more than culture, but false-positives occur Urine and vaginal swabs for field studies - patient self-collected, easy handling, easy shipping, easy processing, less costs |
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Principles of STD Prevention
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Early detection and treatment
High risk group screening Screening for all STDs Counseling Partner notification Education & behavior modification |
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Patient Management – general principles
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Screen for all STDs
Counselling for HIV testing Contact tracing – it “takes two to tango” Prevention of infection – barrier methods Education : Patient education reg. risks of transmitting infection, risks of acquiring other infections Community education esp. in high-risk situations like brothels, truck-drivers etc. |
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What is the WHO Approach to STDs?
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Syndromic management of STDs in developing countries*
Based on history and certain clinical features Useful in places with inadequate diagnostic facilities and expertise Successful approach in many trials (nurses in Zimbabwe; Mwanza, Tanzania HIVdecreasd 42%) |
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Prevention of STDs - basics
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Diseases based purely on behavior should be easier to control than those spread by other means -eg; respiratory
STDs need not be a single infection - always screen for other STDs and HIV STDs affect men and women of all backgrounds and economic levels - common in teens and younger adults Having an STD increases the risk of acquiring HIV infection The main STDs have effective treatment. Therefore, early detection is a priority. |
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* What are the Measures of Potential Efficacy of a Screening Program
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Proportion of infected participants effectively treated
Proportion of sexual contacts effectively treated Proportion of total at-risk population included |
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STD - Education of High Risk Groups
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Regular checkups even in the absence of symptoms, esp. if there is a new partner.
Recognize common symptoms of STDs - use of picture charts Seek medical care at earliest symptoms Avoid practices with increased risk -sex during menstruation, douching, anal intercouse Targeting groups can drive them underground! |
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STD – HIV Interaction
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STDs ↑ HIV transmission
Genital ulcers increase HIV acquisition risk 10 times Non-ulcerative STDs also increase risk at lower levels Having dual STD and HIV infection increases the levels of HIV secreted (eg; HIV secretion 10 times higher in gonorrhea) Increased inflammatory cells – CD4 cells, APCs Having an STD leads to increased acquisition as well as increased transmission |
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HIV prevalence rate and frquency of std episodes
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The more stds episodes you have the greater the risk of HIV
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STD Treatment Trial Mwanza, Tanzania
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Community-level, randomized clinical trial
12 villages in one region with very few medical facilities; 6 intervention & 6 control villages Intervention: "syndromic" STD treatment in village health center Evaluation: STD/HIV tests on 1,000 adults from each village before and 2-years after intervention Result: 42% decrease in HIV incidence |
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Rakai, Uganda study
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Community-level, controlled, randomized trial
Home-based prophylaxis for all treatable STIs Every 10 months – screening and prophylaxis 6605 HIV- in intervention gp; 6124 in control gp Found no difference in HIV incidence between intervention and control villages, although incidence of STDs decreased. |
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Rakai, Uganda study Conclusions
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Lower prevalence of STIs in Rakai - ?strategy works only with high STD prevalence
Symptomatic STIs more important in HIV transmission (treatment vs. prophylaxis) Behavioral interventions should be integral to control programs |
