Image copyright Getty Images Image caption Health officials are investigating how two employees contracted the virus in the West Coast hospital
Two employees who worked at the same Maryland medical centre as a woman who later contracted the disease in Australia have now tested positive for monkeypox.
Officials say the workers are isolated in an isolated area of Walter Reed National Military Medical Centre in Maryland, which diagnoses soldiers returning from the battlefield.
On Friday, Queensland health authorities confirmed the patient was also from the US.
The military hospital has 16 beds for treating patients.
The patient in Australia had travelled to Nigeria.
Read more: How common is monkeypox?
Also on Friday, a Maryland man was diagnosed with the virus after a recently returned soldier had just displayed symptoms, a spokeswoman for the US Centers for Disease Control and Prevention said.
The infectious disease specialist working at Walter Reed is being placed on leave and the hospital is “taking precautions to support the investigation and the soldier’s recovery”, she said.
The patient at Walter Reed “most likely” contracted the monkeypox virus while in Sierra Leone on a relief mission with the aid group, Samaritan’s Purse, last month, said a Reuters news agency reporter.
The unnamed infected soldier was treated at Walter Reed in recent days and taken to hospital on Thursday.
According to the World Health Organization, monkeypox is transmitted by close contact with animals with the virus, including primates, rodents, dogs and wild birds.
The illness develops into a fever, a rash, headache, sore throat, backache, aching muscles and swollen lymph nodes and can be spread via contact with an infected person’s body fluids.