The first records of the Carrier Virus were on Ilona. The disease caused by the virus was described as a rot, or carie, of the body. A translation error from Illonan to Cosprak (and subsequently to the other languages of the IU member islands) changed the virus’s name to Carrier, and so most medical records will list the virus as the Carrier Virus.
Patients exhibited symptoms of muscular and epithelial necrosis, causing the patient’s tissue to die. Amputation was the most common method of stopping the spread of the virus, but there was a 100% fatality rate in cases where the patient’s bloodstream had been breached. The Carrier Virus’ original host is the bacteria Detorium styphi, a species native to Pleoh. D. styphi are decomposers as well as a cannibalistic species; the cyclic food chain keeps the virus thriving within a population. Humans are a dead-end host to the virus, although human-human transmission is possible through transfer of bodily fluids such as blood.
Hélène Ghermond discovered the Carrier virus while analyzing blood samples taken from the first IU explorers of Pleoh. Many of the crew members had died after their voyage. Nurses at the hospital described the patients as having physical similarities to that of corpses; patches of their skin would darken before it spread to the rest of their arm. The dark spots would appear mummified, and there was a rapid decay in neuromuscular control of the arm. Amputation was the typical treatment, but for some patients, the infection had already spread to other tissues within inside their body that the doctors could not surgically remove. No antibiotics could stop the disease; it was thought that the infection was caused by either a virus or a pan-antibiotic-resistant bacteria.
Ghermond was able to confirm the presence of the virus by injecting the blood samples into cultivated human tissues. The human tissues had been treated with a radioactive molecular marker that bound to human DNA. After the injection, the cells were treated with mitotic inhibitors, lysed, and karyotyped, and it was found that the DNA of the infected cells displayed different banding patterns than that of a normal human karyotype, suggesting that the DNA of the infected cells had been altered. Ghermond’s follow-up experiment involved isolating and sequencing the foreign DNA from the blood samples as well as sequencing the DNA of the infected human cells. Although it is possible for bacteria to transfer genes into the human genome, the fact that a significantly large percent of the foreign DNA had been inserted into the infected cells, along with the fact that the genomic length of the foreign DNA was significantly shorter than that of a typical infectious bacterium, suggested that the infectious agent was a virus.
After expeditions to Pleoh were stopped, there were no more reported cases of the Carrier Virus for many years. However, a widespread epidemic occurred on Nezuma during the War of the Atolls. It was not until after the war when doctors were sent to Nezuma to contain the epidemic that the cause for the epidemic was discovered: viral quantities of the Carrier Virus were found in the polluted Nezuman water. An expedition of biologists went to the source of the pollution on Pleoh and found great quantities of the Carrier Virus within the surviving microfauna that had adapted to the toxic pollution. The wastes that the IU dumped on Pleoh had killed many of the local fauna but resulted in a boom in the population of bacterial decomposers that had served as the Carrier Virus’ natural host. The durability of the decomposers enabled them to survive the transport from Pleoh to Nezuma, keeping the Carrier Viruses safely intact as well.
There were ongoing efforts to stop the spread of the virus on Nezuma at the time of departure. The IU quarantined individuals under martial law so that the virus could not spread to other islands. As there were still anti-IU rebels residing on Nezuma, there were fears that rebels would incubate the virus for usage as a bioweapon.
There is currently no cure for Carrier virus. The best method of prevention is vaccination. During this process, three dosages of Carrier Virus’s antigens are administered to the patient over a course of two weeks. Testing and vaccination for the Carrier Virus were required for passengers on the Ingenuity to prevent possible epidemics, either from an infected passenger or from infected D. styphi that somehow made it onboard the ship.