The Guantánamo prison this summer suddenly offered voluntary HIV tests to its long-held war-on-terror captives, including former CIA prisoners kept in seclusion, after a detainee came down with shingles and gave chickenpox to a fellow captive in a communal prison block, the Miami Herald has learned.

None of those who were tested were found to be HIV positive, but prison medical staff concluded that at least 23 captives needed chickenpox vaccinations. All but one of the prisoners agreed to get it.

At the prison, a Navy spokesman refused to discuss the medical testing program. Navy Capt. Christopher Scholl said by email from the base that no civilian, guard or detainee “has or had HIV” at the detention center of 116 captives with a staff of 2,000 troops and Pentagon contractors.

However, at the U.S. Southern Command, which has oversight of the prison, Army Col. Lisa Garcia said the program was basic “preventive care” that emerged from an episode in May when one captive came down with shingles, and another caught chickenpox from him. The prison quarantined 16 captives who had shared communal prayer, dining and recreation space with the two sick men, Garcia said, and all agreed to be voluntarily vaccinated — twice.

“Prior to offering the vaccine, it is preferable to know the immune status of individuals,” Garcia said. So prison staff “conducted voluntary blood draws to assess prior immunity to varicella and HIV status.” Varicella is the virus that causes chickenpox and shingles.

“The quarantined detainees remained under medical observation until the virus incubation period expired,” she said of the May episode. “And there were no new cases of chickenpox or shingles among this group.”

​But reporting by the Miami Herald found the Navy did far more sweeping testing, this time voluntary — a decade after the Pentagon drew blood from the captives without their consent to determine there was no HIV in the then-larger Guantánamo detention center population.

Captive Ammar al Baluchi, an alleged 9/11 conspirator who has been held by the CIA or U.S. military since 2003, was offered a chickenpox vaccination earlier this year, without explanation, and asked his defense team to research the wisdom of getting one. Baluchi’s attorney, Jay Connell, said he was unsure whether Baluchi, 38, got vaccinated.

As a former CIA prisoner who was subjected to the spy agency’s “enhanced interrogation techniques,” Baluchi has no contact with the communal captives. He is kept in segregation in a secret prison of just 15 captives, Camp 7, with a separate medical staff and guard force.

Then in June, medical staff invited captive Ramzi bin al Shibh, 43, another alleged 9/11 conspirator, in custody since 2002, to give blood for an HIV/shingles/chickenpox test, according to his attorney, Jim Harrington. “This was something that just came out of the blue,” Harrington said. “They asked everybody.”

Bin al Shibh refused and, according to Harrington, said other Camp 7 detainees were likewise offered and refused.

So did 74-pound hunger striker Tariq Ba Odah, in his 30s, who is kept in a detention setting separate from the former CIA prisoners and the 16 quarantined men.

Harrington said bin al Shibh asked medical staff why they were doing it, and asked if they had spoken with the detainees’ lawyers. They did not. Harrington said defense teams first learned about it in an inquiry from the Herald, and were formally asking the detention center for an explanation.

The Herald first learned of the testing program in a sworn July 30 affidavit by the prison’s chief medical officer in the federal court case of Ba Odah — a 5-foot-3-inch Yemeni who has been tube fed since 2007 for refusing to eat to protest his continued detention.

Ba Odah, cleared since 2010 for release to a country willing to safely resettle him, refused a June 9 blood draw “to conduct labs to test for chickenpox, shingles and HIV,” according to the doctor, a Navy commander whose name was blacked out.

As a hunger striker, Ba Odah is denied communal captivity under a prison policy adopted in 2013, at the height of the ongoing hunger strike. Troops keep each hunger striker in a solitary cell to make it easier for guards to watch if he eats and strap him to a restraint chair for naso-gastric feeding.

Garcia said figures provided by the prison showed 95 detainees agreed to be tested — none was HIV positive. The test found that 23 detainees needed chickenpox vaccinations, and all but one agreed to get it.

That leaves 18 detainees who refused HIV/chickenpox/shingles testing and 19 who refused the test or vaccination. If a detainee comes down with shingles and lives in the same block as a detainee who refused the test or vaccination, the untested or unvaccinated detainee will be quarantined.

Disclosure of the episode comes at a time when the Department of Defense has been surveying U.S. locations that would serve as a suitable lockup for about 64 of the captives, those considered eligible for trial or too dangerous to release. Part of the effort to transfer the men to the United States would be to give an inevitably aging population access to better, immediate healthcare than a revolving team of Navy medical staff can provide at remote Guantánamo.

Most of the captives are in their 30s and 40s, although two are over 60.

Garcia declined to identify the captive who came down with shingles, which is a reemergence of the virus that causes chickenpox and typically appears in older adults in particularly stressful situations. Medical staff and attorneys have described this year as a particularly stressful one for the 69 Yemeni detainees at Guantánamo, 52 of whom are cleared for release with security assurances, because of growing internecine violence in their homeland that has cut off communications through the International Red Cross.

Doctors contacted by the Herald were particularly puzzled by the HIV testing program because, as the military has acknowledged, Guantánamo medical records show all captives were screened for HIV in the first years of their captivity. The last detainee got to Guantánamo in 2008.

Retired Navy Capt. Albert J. Shimkus Jr., who had oversight of Guantánamo detainee healthcare as command surgeon when the Pentagon set up the detention center in 2002, said that as the detainees arrived each was HIV tested in “a wide screening” to get “a baseline to understand who these people were physiologically.”

The goal, he said, was “do a broad spectrum of finding out if they were healthy or not and to intervene appropriately ... with the best possible treatment for these people.”

Now, many years later, Shimkus said, a detainee “certainly has a right to refuse” such a blood test.

At Guantánamo, spokesman Scholl said by email that detainees “receive the same level of on-station medical care as our service men and women” including “preventative health screening, comprehensive evaluation, and medication management.”

“Screening is voluntary unless it represents a true public health/communicable disease threat,” he added, “which up to this point has not happened.”