Possible false negatives

[Anonimus]

Hello Terri,

I am a male. I began to date a female.

We had unprotected sex for three days continued (from dec. 16th to dec. 18th). We agreed to get tested on everything before we engage in more sexual activity.

We got tested the same day. 17 days after our last sexual encounter (Jan. 4th). We got tested in different labs since we are from different cities.

Her HSV-2 results were the following:
IGG: 1.78
IGM: 0.30

My results were:
IGG: 0.83
IGM: 0.74

The relationship stopped there.

I wasn’t managing well the anxiety, so I couldn’t wait the 3 months and got tested again 11ish weeks after the last sexual encounter (March 2nd). Muy results:

IGG: 6.646 (This one, the range values are different). It says
<16 negative
16-22 Indeterminate
>22 Positive

IGM: 1.92 (This one is like the others)
< 0.9 Negative
0.9-1.1 Indeterminate
> 1.1 Positive

For some reason that I don’t know, they performed another kind of test for the IGG.

My IGM is positive, and negative IGG.

I talked with her. I was pretty confident I was going to be negative because, with the information she gave me, I was sure she was a false negative. She told me she had sex 5 months before she had sex with me, so that gave me confidence for being a false positive. I assumed 5 months was time enough to be a solid positive. She told me she never had symptoms and me neither since the last encounter.

The tests were done in Ecuador. I know you don’t recommend getting the IGM, but they always make you get it. But here they don’t test for HSV-1. They assume everybody has it. I know I have oral HSV-1. She also has oral HSV-1.

My questions are:

What are her % chances of her being false positive?
Can she test again and get an indeterminate value again?
Should I wait 16 weeks to get tested again on IGG?
What are my % chances, according to you, of me being a false negative IGM?
Should I get worried about my IGM value?

Regards,

[Terri Warren]

What are her % chances of her being false positive?
Probably around 75%
Can she test again and get an indeterminate value again?
Sure
Should I wait 16 weeks to get tested again on IGG?
No, 12 weeks is adequate – probably 10 weeks for IgG is enough

What are my % chances, according to you, of me being a false negative IGM?
I don’t deal with IgM as they have such poor performance

Should I get worried about my IGM value?
They are most often wrong. You’ll know more when you repeat the IgG

Terri

• This reply was modified 2 weeks, 1 day ago by Terri Warren.

[Anonimus]

Thanks for your answer.

I asked the lab why they used different tests on my IGM and IGG.
They said that they used Euroimmun in both. It came back positive for IGM, so they decided to confirm with the Elisa.

My questions are:

1. Since they used Euroimmun for IGG. Is this test as reliable as the ELIsA with the same window periods of 12 weeks?

2. What are my % chances of being a false positive?

3. There is no western blot here. What should can we do if her results come back again with a same range 1.1-3.5? Is there another kind of confirmatory test?

4. Why is 10 weeks probably enough?

5. If she gets a negative IGG? That’s all. No need for me test again?

[Anonimus]

2. My second question was wrong.
It is: “what are my % chances of testing negative on IGG in 12 weeks? (Considering I tested negative at 10 weeks).

6. I looked at my prior tests. With Euroimmun. My IGG tests for hsv-2 have been 13, 10, 14, in three different years as I get tested regularly. This one came as 6.646. Does this result means something compared to the other results?

7. What % of people seroconvert to IGG at 74 days (10/11ish weeks) after exposure?

[Anonimus]

Do I have to pay? Or do my follow up questions have to be a new post?

[Terri Warren]

1. Since they used Euroimmun for IGG. Is this test as reliable as the ELIsA with the same window periods of 12 weeks?
I am not as familiar with that test so I can’t provide an answer that I would have any confidence in.

2. What are my % chances of being a false positive?
The answer to number one is also true here I just don’t know.

3. There is no western blot here. What should can we do if her results come back again with a same range 1.1-3.5? Is there another kind of confirmatory test?
The western blot can be sent to the University of Washington from many places across the countries if you wish to do that. We have, for example, a person in London who processes western blot’s for us after they have had a telehealth visit with me.

4. Why is 10 weeks probably enough?
Few people seroconvert after 10 weeks

5. If she gets a negative IGG? That’s all. No need for me test again?
I would say that is likely true but because I don’t know enough about this test and its accuracy I can’t give you the answers that you seek about this.
Your index value appears to reflect a negative result but I don’t know enough about the sensitivity and specificity of this test to be more certain

Terri

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