Manus Island detainees are being placed in medical isolation at a rate of nearly one a day, and almost a quarter have required quarantine, hospitalisation or other medical treatment over the past eight months, official statistics show.

And the asylum seekers themselves said their care is getting worse. Detainees beaten in February’s unrest said they were still suffering with their injuries, and others said they have had medication taken from them, been given expired drugs, or waited months for treatment.

“It hurts all the time,” one detainee suffering a long-term infection said. “I know I will die here.”

Official logs from the detention centre showed detainees were being put in medical isolation for contagious illnesses – such as fever, gastroenteritis or skin infections – at a rate of nearly one person a day.

Photograph: supplied

And nearly a quarter of all asylum seekers held in the Manus Island detention centre have needed medical isolation or hospitalisation in the past eight months.

Management data from the detention centre showed that during 212 days between late April and late November, 138 detainees were medically isolated a total of 194 times.

Several detainees were placed in isolation more than once. One man was isolated seven times.

Photograph: supplied

Thirty-four detainees were held at the International Health and Medical Services (IHMS) medical centre within the detention centre, while 103 men were sent to Port Moresby hospital and 18 were urgently evacuated – “medivacced” – to Australia with a life-threatening illness or injury.

During the time the logs cover, there were 1,028 detainees held on Manus Island, all men. In total 244 detainees, or 24%, required isolation or hospitalisation.

IHMS, which is contracted to provide healthcare to asylum seekers, declined to comment.

Two asylum seekers detained on Manus Island have died this year: Reza Barati, who was beaten with a wooden pole and had a rock dropped on his head during riots in February, and Hamid Kehazaei, who died in Brisbane in September when a skin infection turned septic, and his transport to hospital was delayed by a visa hold-up.

But a series of Guardian Australia interviews with staff and detainees from the island have revealed a litany of further healthcare complaints:

• One man, who had medication for burns to his face taken from him on Christmas Island before he reached Manus, wrote a letter of complaint about his lack of medical treatment in January. He received a reply three months later, which stated: “if a referral had been made on your behalf then due process will be followed, this may be timely which should have been explained to you at the time of your consult. The length of time is unfortunately outside of the control of IHMS staff. We apologise for any distress which the length of your wait may have occurred.” IHMS’s contract requires that a detainee must have a consultation with a healthcare practitioner within 72 hours of a request for a medical consultation. The man was emergency medivacced to Australia in July.

• On several occasions, detainees have been given medication that has expired. A letter from IHMS to one detainee read: “IHMS apologises that you were given eye drops that had expired … please be assured that the doctor concerned has been made aware of the issue and is also apologetic. Thank you for bringing this issue to our attention, and as IHMS is committed to providing quality care, appropriate measures have been taken to ensure that this incident is not repeated.” The letter was signed by the IHMS health services manager. The patient saw another doctor and received current medicine.

IHMS apologises for the administration of out-of-date eye drops. Photograph: supplied

• Another man was first taken to the IHMS medical centre with an ear infection in June. By December, the infection had worsened. The man’s ear was bleeding every day and he had lost all hearing in it. “I have suffering for pain. Every day I lose weight. Now I’m so thin. I have pain. I near to die,” he said.

• One man is still suffering a serious limb injury sustained when he was beaten during the disturbances in the Manus detention centre in February (in which Barati died). He complained, too, of severe headaches: “I go to the doctor, but nothing happens. I get given 10 pills a day, but they have no effect on my sickness. I don’t know what the pills are called. I am in a very bad situation at the moment, I can’t continue my life this way.” A letter he received from the IHMS health services manager read: “I acknowledge it is not an ideal environment, however I assure you we strive to provide the best care available.”

IHMS seeks to reassure a detainee still suffering after being injured in February’s unrest. Photograph: supplied

• Another man is in pain after his teeth were smashed when hit across the face with a wooden object during the same unrest in February. It is painful for him to eat, and he has lost a substantial amount of weight. He also has unresolved leg injuries, sustained during the riots, and said he has developed an addiction to painkillers. A dentist arrived on the island in mid-November and is working through the backlog.

• Several detainees taken to Port Moresby hospital have refused treatment there, reportedly because of unhygienic conditions in the hospital.

Dr Richard Kidd, Queensland representative for the Australian Medical Association and co-founder of Doctors for Refugees, said there were “huge question marks” over the standard of healthcare being provided to detainees on Manus.

“If you look at the examples of the recent death of Hamid Kehazaei, who came from Manus Island and died in Brisbane, there are very, very serious questions around clinical governance, around access to effective and appropriate medical care, and the timeliness to enact an emergency evacuation,” he said.

He said leaked patient notes showed the Manus health facility did not have the right antibiotics, recommended in the PNG medical guidelines.

Kidd said many of the detainees were survivors of torture and trauma in their home countries, and were arriving in Australia’s care weakened, often dehydrated and malnourished, from their boat journey.

“On a place like Manus Island, I would expect high rates of typhoid and hepatitis. Gastroenteritis is going to be rife, particularly if there is limited access to clean latrines, and certainly if you have trouble removing sewage cleanly and safely,” he said.

He described providing proper healthcare on Manus as almost impossible, and condemned the government’s offshore processing policy.

“It’s really an evil policy, they are saying publicly they want to crush these people so others don’t come. To deliberately harm another human being, that is completely unacceptable, it is morally wrong and just indefensible,” he said.

IHMS declined to answer any questions from Guardian Australia on the medical care provided to detainees on Manus, instead referring inquiries to the immigration department’s communications office. The department did not respond.

Australian government staff told the United Nations committee against torture in November that healthcare in the immigration detention centres was comparable to that available in Australia.

Mark Cormack, from the Department of Immigration and Border Protection, told the committee in Geneva: “Healthcare services are not denied to asylum seekers.”

“International Health and Medical Services are required to deliver healthcare that is the best available in the circumstances and broadly comparable with the health services within the Australian community,” he said.

A parliamentary committee found Australia had “effective control” of the Manus Island detention centre and was responsible for the care of the people held there.