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Mpox Sample Submission Updates
Minnesota Infectious Disease Laboratory
November 2022 Update:
The Infectious Disease Laboratory (IDL), a section of the Minnesota Department of Health's Public Health Laboratory (MDH-PHL), continues to offer mpox (formerly known as "monkeypox (MPX)") specimen testing to better understand the emergence and trends circulating in the community. While health care facilities are encouraged to send samples to their regular reference labs, IDL will test samples as needed on a reduced testing schedule: currently M/T/F.
Major commercial labs continue to offer mpox testing; testing in Minnesota is also available at a reduced cadence via the Minnesota Department of Health’s Public Health Laboratory (MDH-PHL).
Regardless of whether testing occurs at commercial labs or MDH-PHL, it remains important to continue reporting suspected cases to MDH so that appropriate public health follow-up actions can be taken.
Specimen collection for mpox is different from many other swab sampling techniques: Please carefully follow the instructions for obtaining a proper sample and use the appropriate swabs and containers. Multiple specimens received at the Infectious Disease Laboratory have resulted in indeterminate results due to poor sampling techniques. Whether health care providers are submitting directly to MDH-PHL or a reference laboratory, it is important to closely follow each laboratory’s collection instructions.
To ensure specimens are not rejected at MDH-PHL or the CDC, please ensure the following guidelines are met:
Each specimen must contain two patient identifiers. Acceptable patient identifiers are:
- patient’s first name and last name, AND
- either date of birth OR sex and age.
Please note that specimen ID and case ID do not count as identifiers per the CDC.
- Patient identifiers should be clearly visible and not covered by other tube labels.
- Ensure the information on the paperwork matches with the specimen(s) submitted. Double-check for misspelled names or transposed numbers on date of birth, etc.
- At the bottom of the Specimen Submission Form (PDF), choose Test Requested: Other and then add mpox.
Acceptable specimen type(s): dry swabs of lesion fluid, lesion surface, and/or lesion crust.
- Submit TWO swabs for each lesion in the same tube.
- Lesion crust must be submitted with a paired lesion swab, in a separate sterile container.
- Vigorously swab or brush the lesion with two separate sterile dry polyester or Dacron swabs.
- Do not place any other material (e.g., foam or other absorbent material) at the bottom of the swab or the specimen will be rejected.
- Break off the applicator of each swab into a 1.5 or 2 mL screw-capped tube with O-ring, or place the entire swab or lesion crust in a separate sterile container: A 15 mL Falcon-type tube is preferred.
Specimen Storage:
- Swabs submitted to IDL must be dry. Do not store in viral or universal transport media (i.e., VTM or UTM)
- Dry swabs should be stored and refrigerated at 4°C within one hour of collection and shipped at refrigeration temperature.
- Refrigerated specimens must be received within 7 days of collection.
- Samples may also be frozen and stored/shipped frozen (-20°C).
| Results text | Interpretation | Notes |
|---|---|---|
| POSITIVE for non-variola orthopoxvirus DNA | Specimen positive for non-variola orthopoxvirus; Mpox positive diagnosis (presumptive) | Specimen will be sent to CDC for further characterization. Treat patient as mpox positive. |
| Negative for non-variola orthopoxvirus DNA | Specimen negative for non-variola orthopoxvirus Mpox negative diagnosis | No mpox virus detected. No further mpox testing performed. |
| EQUIVOCAL for non-variola orthopoxvirus DNA | Result suggestive of low viral particle collection, however, the signal is too low to determine conclusively | Suggest recollection and submission of a new mpox sample, if clinically indicated. No further mpox testing performed. |
| Indeterminate | Specimen failed internal quality controls; result invalid | Recollect and submit new mpox sample. |
| Not tested | Specimen was not tested | Incomplete or unresolvable patient data; incorrectly shipped/packaged; incorrect storage temperature; arrival >7 days post-collection (refrigerated samples); etc. |