After problems with earlier samples, a fuller picture of the outbreak is emerging following another round of testing.
A group of 78 more samples, a variety of types, are on their way to the INRB lab in Kinshasa.
Hepatitis A virus and vaccinia virus showed evidence for sexual transmission but no evidence for detection in the semen.
Of 12 samples, 10 were malaria-positive, but officials continue to investigate other contributing factors.
31 people have died and 406 people have been sickened by the illness, which causes fever, headache, cough, runny nose, and body aches.
As DRC officials await test results, WHO experts are also bringing medicine and test equipment to help local responders.
Children younger than 5 years are the most affected group and account for the largest portion of deaths.
The main symptoms are fever, headache, runny nose, breathing problems, and anemia.
The rise in community transmission is likely due to decreased transmission during the COVID-19 pandemic, leading more people to be vulnerable to B19.
The researchers measured serologic evidence of immunity against varicella, measles, mumps, rubella, hepatitis A, and hepatitis B.
