General Statistics about STD/STIs in the United States
Ages
All ages
US Population
308,827,000
.Under 5 years
20,110,000
.5 to 9 years
20,416,000
.10 to 14 years
20,605,000
.15 to 19 years
21,239,000
.20 to 24 years
21,878,000
.25 to 29 years
20,893,000
.30 to 34 years
20,326,000
.35 to 39 years
19,140,000
.40 to 44 years
20,787,000
.45 to 49 years
21,583,000
.50 to 54 years
22,372,000
.55 to 59 years
20,470,000
.60 to 64 years
17,501,000
.65 to 69 years
13,599,000
.70 to 74 years
9,784,000
.75 to 79 years
7,331,000
.80 to 84 years
5,786,000
.85 years and
over
5,006,000
(Top picture) Roughly 20 million new STIs occur each year in the US, half of which are for young
people (ages 15-24).
(Bottom picture) Roughly 110 million STIs currently exist in the US.
Sources: http://www.cdc.gov/std/stats/STI-Estimates-Fact-Sheet-Feb-2013.pdf
Important note about male condoms: Condoms can be expected to provide different levels of
protection for various STDs, depending on differences in how the diseases or infections are transmitted.
Male condoms may not cover all infected areas or areas that could become infected. Thus, they are
likely to provide greater protection against STDs that are transmitted only by genital fluids (STDs such as
gonorrhea, chlamydia, trichomoniasis, and HIV infection) than against infections that are transmitted
primarily by skin-to-skin contact, which may or may not infect areas covered by a condom (STDs such as
genital herpes, human papillomavirus [HPV] infection, syphilis, and chancroid).
http://www.cdc.gov/condomeffectiveness/brief.html
Clarification between STD vs. STI:
“STD and STI are two terms that often mean the same thing — but the ‘D’ stands for ‘disease,’ while the
‘I’ stands for ‘infection.’ Medically, infections are only called diseases when they cause symptoms, and
many STIs don’t have any symptoms. So that’s why you may hear people say STIs – it’s technically more
accurate, and also reminds people that there are often no symptoms so it’s important to get tested.”
http://plannedparenthood.tumblr.com/post/33600737905/std-vs-sti
“Sexually transmitted infection (STI) is another name for sexually transmitted disease (STD). The name
STI is often preferred because there are a few STDs, such as chlamydia, that can infect a person without
causing any actual disease (i.e. unpleasant symptoms). Someone without symptoms may not think of
themselves as having a disease, but they may still have an infection that needs treating.”
http://www.avert.org/stis-stds.htm
Scenario #1: Engaging in sexual activity without any type of protection
Materials:
[clear] cups (8-12oz works well)
Water
Paper confetti —acts as a distractor
Sodium Hydroxide pellets—acts as the virus
Phenolphthalein—acts as a “revealer” by making water turn pink if the virus is present
Note: Sodium Hydroxide (NaOH) pellets and Phenolphthalein are cheap and readily available to
chemistry lab instructors.
Preparation
Before the day of the activity: Prepare the virus (and “distractor”)
*In a separate quart-sized container, dissolve the Sodium Hydroxide (NaOH) pellets into a quart of water
*Fill a zip lock bag with paper confetti (or the holes from hole-punched paper)
On the day of the activity: Prepare the [clear] cups
*For this example, assume that a) the class has 30 students and b) 4 students have an STD
*Fill 26 cups below half full with plain water
*Fill 4 cups below half full with the Sodium Hydroxide solution
*If you want to use “distractors”, place a tablespoon of paper confetti in 4 cups (A. The confetti could go
only in cups with plain water, or some confetti could go into both cups with clean water and cups with
Sodium Hydroxide—you choose!)
General Sequence of the Activity
1) Ask students to come get their cup of liquid
2) Ask students to pick a partner and then…
a) Student A pours all of the contents of his/her cup into student B’s cup
b) Student B pours half of the contents back into Student A’s cup
c) This completes the first “cycle”
3) Repeat step 2 as many times as you (the teacher) desire
Recommendations:
*Have two cups with liquid set aside before the activity so that you can model for the students exactly
how to pour the liquids during the activity.
*Write down any questions you want to ask before, during, and after the activity. A lot is going on
during this activity and it is easy to reach information/logistical overload.
4) Once students have completed the required number of mixing cycles, put a drop of Phenolphthalein
in each student’s cup. A student’s cup will turn PINK if it has the virus.
Note: You can tailor the setup according to 1) the number of students you have, 2) whether or not you
want to use “distractors”
Questions you can ask:
1) Before the mixing…
How many of you think you have the virus right now?
How many of you think you will get the virus after, say, 3 cycles of interactions?
If I were to randomly select someone, what would be the probability he/she would have the
virus?
2) After the mixing, but before students find out who has the virus…
Who were the original carriers of the virus? (Exploit perception bias)
How many of you think you have the virus now?
Did you use any strategies to minimize the chance that you would get the virus?
3) After students find out who had the virus…
Why do you think we used “distractors” in this activity?
Can you figure out who were the original carriers of the virus?
If I were to randomly select someone now, what would be the probability that he/she would
have the virus?
How many cycles do you think we would need to have before everyone got the virus?
Scenario #2: Engaging in sexual activity with protection (male condom)
Background
In the preceding scenario, students carried out an activity that simulated the effects of engaging in
sexual activities without any type of contractive protection. The students could see how quickly a virus
could spread if no protection is used. The response to this phenomenon is to use contraceptives.
However, contraceptives are not immune to failures. The following activity is designed to help students
simulate contraceptive failures in the context of male condoms and take into account both STD
transmissions as well as pregnancies upon contraceptive failures.
Materials
2 dice per student
Worksheet (see attached)
Preparation
Before the day of the activity: Prepare the virus
*On the back of [20%?] of the handouts that students will receive, lightly write in pencil in the top left
corner the first letter of an STD. (For example, “H” could represent herpes.)
*Decide which days in the activity pregnancy can occur
*Prepare the handouts you plan to use for the activity (for example, the “contraceptive success/failure
handout” and any handouts containing relevant studies or summaries of studies)
On the day of the activity:
*Establish with your class what the probability of contraceptive failure will be for the activity
*Once the probability of contraceptive failure is established, identify the roll that students will need to
make in order for the contraceptive to “fail”. For example, if the class decides that the contraceptive will
fail 5% of the time, then the class could decide that a roll of two six-sided dice resulting in “1,1” or “2,2”
would be indicative of a contraceptive failure.
General Sequence of the Activity
1) Distribute to each student the “contraceptive success/failure handout”
2) Ask students to pick a partner and then…
a) Student A rolls both of his dice
i) If the dice do NOT produce a “1,1” or “2,2”, then the contraceptive did not fail. Thus,
both students circle “NO” for the question “Did the contraceptive fail?” for that
encounter and then proceed with the next cycle
ii) If the dice DO produce a “1,1” or “2,2”, then the contraceptive DID fail. Thus, both
students circle “YES” for the question “Did the contraceptive fail?” for that encounter.
Then, both students discreetly show each other the back of their handouts.
*If neither student has the STD, then the students proceed with the next cycle.
*If one student has the STD, then the other student write on his/her handout
the letter of the STD he/she just contracted.
b) The students then decide to stay with their current partner or pick another partner. This cycle
repeats until the worksheet is complete.
3) After the students have completed all 50 cycles, the teacher will announce to the students which
encounters in which pregnancy was possible. (Pregnancies are possible roughly 2-3 out of every 28 days,
so the teacher may choose 3-4 encounters for which pregnancies were possible—say, encounters # 10,
#20, #30, and #40.)
i) Students will look at their handout to see if their contraceptive failed on the dates that the
teacher mentioned. If their contraceptive failed on the mentioned dates, then the student got
pregnant or got someone else pregnant on those dates.
Questions you can ask:
*In this simulation, how many failures occurred? Pregnancies? New STDs?
*Based on this activity, discuss the validity of the claim “Using condoms will keep you safe.”
*Are there any ways to minimize/eliminate getting pregnant or getting an STD?
*See worksheet
The activity for Scenario #2 and corresponding worksheets were created by Luke Smith, Auburn
University Montgomery.
Instructions for “With Protection” Scenario:
1. For each encounter, roll the dice. If you get a sum of 3, then your contraceptive failed.
2. If your contraceptive failed, discretely look on the BACK of your partner’s paper to see if he/she has a
disease (denoted by a letter). If yes, then you now have that disease and must write the same letter on
the back of your paper.
3. Each time you contract an STD, record on the back of your sheet the encounter on which it occurred.
Encounter #
Did the contraceptive fail?
Encounter #
Did the contraceptive fail?
1
YES
NO
26
YES
NO
2
YES
NO
27
YES
NO
3
YES
NO
28
YES
NO
4
YES
NO
29
YES
NO
5
YES
NO
30
YES
NO
6
YES
NO
31
YES
NO
7
YES
NO
32
YES
NO
8
YES
NO
33
YES
NO
9
YES
NO
34
YES
NO
10
YES
NO
35
YES
NO
11
YES
NO
36
YES
NO
12
YES
NO
37
YES
NO
13
YES
NO
38
YES
NO
14
YES
NO
39
YES
NO
15
YES
NO
40
YES
NO
16
YES
NO
41
YES
NO
17
YES
NO
42
YES
NO
18
YES
NO
43
YES
NO
19
YES
NO
44
YES
NO
20
YES
NO
45
YES
NO
21
YES
NO
46
YES
NO
22
YES
NO
47
YES
NO
23
YES
NO
48
YES
NO
24
YES
NO
49
YES
NO
25
YES
NO
50
YES
NO
Facts for this activity:
Condoms have a failure rate of approximately 5%.
At least 1 in 5 people have an STD.
A woman can get pregnant 2 days every month (28 day period)
Name: _________________________
Related Worksheet
Part 1: Without Protection
There are 10 people in a room and two of them have a virus.
Before anyone does anything, what is the probability of selecting someone who has the virus?
__________
Let’s assume that each of the 10 people have one encounter.
What is the probability now of selecting someone who has the virus? _____________
Let’s assume that each of the 10 people have a second encounter.
What is the probability now of selecting someone who has the virus? _____________
Let’s assume that each of the 10 people have yet another encounter (their 3rd encounter).
What is the probability of selecting someone who has the virus? ____________
Part 2: With Protection
Assuming that condoms have a failure rate of 5%, 1 out of 5 people have an STD, and women can get
pregnant 2 days out of every 28 day period…
What is the probability that on a given day, a girl is fertile? __________
What is the probability that on a given use, the condom fails? __________
What is the probability that in a single encounter, both the condom fails and the girl is fertile?
____________
If we assume that the condom fails, what is the probability that a person will get an STD? __________
If we assume that the condom fails, what is the probability that a woman could get pregnant?
_________
If we assume that a woman has an encounter while she is fertile, what is the probability that the
condom will fail (and therefore the man could get her pregnant)? _____________
If someone engaged in 50 encounters and used a condom, how many times on average would the
condom fail? ___________
What is the probability that someone could have 50 encounters and the condom work every time?
_________
Name: _________________________
Answer Key for Related Worksheet
Part 1: Without Protection
There are 10 people in a room and two of them have a virus.
Before anyone does anything, what is the probability of selecting someone who has the virus?
_____2/10
Let’s assume that each of the 10 people have one encounter.
What is the probability now of selecting someone who has the virus? __between 2/10 and 4/10
Let’s assume that each of the 10 people have a second encounter.
What is the probability now of selecting someone who has the virus? ___between 2/10 and 8/10
Let’s assume that each of the 10 people have yet another encounter (their 3rd encounter).
What is the probability of selecting someone who has the virus? ____between 2/10 and 10/10
Part 2: With Protection
Assuming that condoms have a failure rate of 5%, 1 out of 5 people have an STD, and women can get
pregnant 2 days out of every 28 day period…
What is the probability that on a given day, a girl is fertile? __________2/28
What is the probability that on a given use, the condom fails? __________5/100
What is the probability that in a single encounter, both the condom fails and the girl is fertile?
______________ 5/100* 2/28
If we assume that the condom fails, what is the probability that a person will get an STD? ______1/5
If we assume that the condom fails, what is the probability that a woman could get pregnant? _____
2/28
If we assume that a woman has an encounter while she is fertile, what is the probability that the
condom will fail (and therefore the man could get her pregnant)? _____________5/100
If someone engaged in 50 encounters and used a condom, how many times on average would the
condom fail? ___________ 50*.05
What is the probability that someone could have 50 encounters and the condom work every time?
________________
(.95)^50
This article came out within the last year. A statement on page 114 caught my attention.