Animal to human transmission The life cycles of the<unk><unk>  The initial infection is believed to occur after an<unk><unk>  is transmitted to a human by contact with an infected animal's body fluids. Evidence strongly implicates bats as the reservoir hosts for<unk><unk> es (however, despite considerable research, infectious<unk><unk> es have never been recovered from bats). Bats drop partially eaten fruit and pulp, then land mammals such as gorillas and duikers feed on this fallen fruit. This chain of events forms a possible indirect means of transmission from the natural host to animal populations. As primates in the area were not found to be infected and fruit bats do not live near the location of the initial zoonotic transmission event in Meliandou, Guinea, it is suspected that the index case occurred after a child had contact with an insectivorous bat from a colony of Angolan free-tailed bats near the village. On 12 January, the journal Nature reported that the<unk>  emergence could be found by studying how bush-meat hunters interacted with the ecosystem. The continent of<unk> has experienced deforestation in several areas or regions; this may contribute to recent outbreaks, including this epidemic, as initial cases have been in the proximity of deforested lands where fruit-eating bats natural habitat may be affected, though 100% evidence does not as yet exist. Human to human transmission Prior to this outbreak, it was believed that human-to-human transmission occurred only via direct contact with blood or bodily fluids from an infected person who is showing symptoms of infection, by contact with the body of a person who had died of<unk> , or by contact with objects recently contaminated with the body fluids of an actively ill infected person. It is now known that the<unk><unk>  can be transmitted sexually. Over time, studies have suggested that the<unk>  can persist in seminal fluid, with a study released in September 2016 suggesting that the<unk>  may survive more than 530 days after infection. EBOV RNA in semen is not the same situation as perseverance of EBOV in semen, however the "clinical significance of low levels of<unk>  RNA in convalescent" individuals who are healthy is unknown. In September 2014, the WHO had reported: "No formal evidence exists of sexual transmission, but sexual transmission from convalescent patients cannot be ruled out. There is evidence that live<unk><unk>  can be isolated in seminal fluids of convalescent men for 82 days after onset of symptoms. Evidence is not available yet beyond 82 days." In April 2015, following a report that the RNA<unk>  had been detected in a semen sample six months after a man's recovery, the WHO issued a statement: "For greater security and prevention of other sexually transmitted infections,<unk>  survivors should consider correct and consistent use of condoms for all sexual acts beyond three months until more information is available." The WHO based their new recommendations on a March 2015 case, in which a Liberian woman who had no contact with the disease other than having had unprotected sex with a man who had had the disease in October 2014, was diagnosed with<unk> . While no evidence of the<unk>  was found in his blood, his semen revealed<unk><unk>  RNA closely matching the variant that infected the woman. However, "doctors don't know if there was any fully formed (and therefore infectious)<unk>  in the guy's semen." It is known that testes are protected from the body's immune system to protect the developing sperm, and it is thought that this same protection may allow the<unk>  to survive in the testes for an unknown time. On 14 September 2015, the body of a girl who had died in Sierra Leone tested positive for<unk>  and it was suspected that she may have contracted the disease from the semen of an<unk>  survivor who was discharged in March 2015. According to some news reports, a new study to be published in the New England Journal of Medicine indicated that the RNA<unk>  could remain in the semen of survivors for up to six months, and according to other researchers, the RNA<unk>  could continue in semen for 82 days and maybe longer. Furthermore,<unk>  RNA had been found up to 284 days post-onset of viral symptoms. Containment difficulties One of the primary reasons for the spread of the disease is the low-quality, functioning health systems in the parts of<unk> where the disease occurs. The risk of transmission is increased among those caring for people infected. Recommended measures when caring for those who are infected include medical isolation via the proper use of boots, gowns, gloves, masks and goggles, and sterilizing all equipment and surfaces. One of the biggest dangers of infection faced by medical staff requires their learning how to properly suit up and remove personal protective equipment. Full training for wearing protective body clothing can take 10 to 14 days. Even with proper isolation equipment available, working conditions such as lack of running water, climate control, and flooring have made direct care difficult. Two American health workers who contracted the disease and later recovered said that to the best of their knowledge, their team of workers had been following "to the letter all of the protocols for safety that were developed by the CDC and WHO", including a full body coverall, several layers of gloves, and face protection including goggles. One of the two, a physician, had worked with patients, but the other was assisting workers to get in and out of their protective gear while wearing protective gear herself. Difficulties in attempting to halt transmission have also included the multiple disease outbreaks across country borders. Dr Peter Piot, the scientist who co-discovered the<unk><unk> , stated that the outbreak was not following its usual linear patterns as mapped out in earlier outbreaks—this time the<unk>  was "hopping" all over the<unk><unk>  epidemic region. Furthermore, most past epidemics had occurred in remote regions, but this outbreak spread to large urban areas, which had increased the number of contacts an infected person might have and made transmission harder to track and break. On 9 December, a study indicated that a single individual introduced the<unk>  into Liberia, causing the most cases of the disease in that country.
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