Screening for Monkeypox by PCR (MPXV)

Friday, 22 July 2022

Monkeypox is caused by infection with monkeypox virus (MPXV). Although monkeypox is being transmitted through sexual contact, the virus can infect anyone who comes into direct contact with the lesions or scabs, body fluids, respiratory droplets or contaminated linens or towels.

The incubation period from the time of contact to the time of first symptoms is between 5–21 days. An individual is contagious until all the scabs have fallen off and there is intact skin underneath.

Clinical diagnosis of monkeypox may be complicated by the possibility of other conditions (chickenpox, HSV, molluscum contagiosum and syphilis, for example). Samples being investigated for other infections, including sexually transmitted infection, should be collected and packaged separately with separate request forms and instruction for other tests.

A definite diagnosis of monkeypox requires specialist testing in the laboratory. This is now being undertaken by TDL.

Monkeypox is diagnosed by PCR testing from a viral swab taken from one single vesicle or ulcer/lesion. UKCA marked swab lesion kits (kit reference KT405) can be ordered through UKCAkits@tdlpathology.com. Samples taken using the swabs provided in these kits (KT405) ensure that the virus is inactivated during transit.

Inactivated samples can be handled safely with other practice samples, and standard laboratory precautions.

Collecting the MPXV swab sample

Instructions are provided in each UKCA kit (KT405).

  1. Label the tube with the patient’s name, date of birth, date of sample collection and site of the sample collection. Unlabelled tubes, or samples without request forms, may result in the swab being delayed or discarded.
  2. Use the dry cotton end of the swab to collect the sample from a single open lesion/sore, or from the surface of the vesicle. Ensure that the swab tip is taken from the suspected vesicle, ulcer or crusted lesion.
  3. Unscrew the tube cap taking care not to touch or pierce the foil top.
  4. Place the swab into the tube containing the transport medium and snap at the black line break point and discard the stick end leaving the swab in the tube.
  5. Replace the lid.