The transmission of a new bird flu virus, known as H7N9, to humans in China is generally seen to have begun as early as mid-February. As of April 30, 24 of the 128 people who were infected were reported to have died, but few people, including experts, believe the numbers released by the Chinese government reflect the real situation.

　　　The Chinese government, severely criticized by the international community in 2002 for hiding pertinent information on the spread of SARS (severe acute respiratory syndrome), obviously has not learned much from their earlier mistakes. Although initially willing to release information this time, the National Health and Family Planning Commission of China’s State Council, which oversees prevention and treatment of infectious diseases among other things, drastically restricted the dissemination of information. Daily press briefings were suddenly reduced to once a week effective April 24.

　　　Masato Tashiro, director of the Influenza Virus Center of the National Institute of Infectious Diseases, points out that it is highly desirable to release information pertaining to an unknown virus every hour of the day. The number of deaths in China attributable to the virus reportedly increased by four in the week during which Beijing withheld information, raising the total to 26 by May 2. However, this is “just the tip of the iceberg,” points out Tashiro, explaining:

　　　“On March 31, the Chinese government released full information on the base sequence of the genes of the bird influenza virus, including RNA (ribonucleic acid). Judging the nature of the virus on the basis of its genes, I feel it is not likely that we would be seeing a high fatality rate at this point. I wouldn’t be surprised, however, if there were a number of Chinese suffering from only mild symptoms, or showing no symptoms at all. In fact, there is a good possibility that the actual number of those in China infected with this specific virus is far larger than has been reported – perhaps to the tune of tens of thousands.”

　　　Medical services in provincial China are grossly inferior to those found in metropolitan areas. People in these regions are poor across the board, many of them economically too hard pressed to visit a hospital even if there is one nearby.  Presumably, there are those who die of bird flu in isolated regions, but statistics do not reflect the deaths of those unable to avail themselves of medical care. This explains why the government announcements can barely be considered to reflect the total picture truthfully.

Jumping the Species Barrier

　　　Despite this, it still is possible to speculate about the specific characteristics of the virus based on the conditions of the patients that we are aware of. Tashiro comments:

　　　“One notable characteristic of H7N9 is that the patients are predominantly the aged, with more than 95% of them over 60 years of age, and men outnumbering women 2 to 1.”

　　　The average life expectancy in China is 71.6 for men and 75.0 for women. Therefore, the “above 60” age bracket actually involves citizens who are “more senior” compared with Japan, where the average life span is 76.6 for men and 83.0 for women.

　　　Why younger people develop only minor symptoms when infected with the H7N9 virus has yet to be sufficiently studied. In the case of infections attributable to H5N1 which spread across the world starting in the second half of 2003, most of the patients were young adults under 40 as well as children. Obviously, these two types of virus contrast sharply with each other.

　　　Some intriguing facts have emerged through the RNA of the H7N9 virus. Explains Tashiro: “The first thing that became evident was that this virus came into being through the cross-breeding of the genes of three different types of bird flu. It further became evident that this virus somehow met several conditions mandatory to enabling it to transmit itself to humans and cause widespread epidemics.”

　　　It was through a mutation that H7N9 became easily transmittable to humans. In other words, it has jumped the species barrier – from birds to human beings. However, in order for the virus to survive, birds and humans offer greatly different host environments. The ideal temperature for the virus to survive and continue multiplication is the bird’s body temperature. At between 40 and 42 degrees Celsius, it is much higher than human body temperature. Meanwhile, human body temperature specifically in the upper respiratory tract, including the nose and the throat, to which the virus can easily be transmitted, is only about 35 degrees Celsius.

　　　Previously, it was thought that the virus could not multiply in a temperature this low. However, H7N9 does multiply even at this temperature. It has managed to survive the obstacle of low temperature through mutation.

　　　Even though the virus has jumped the barriers of species and temperature, it still will be unable to attain human-to-human transmission unless it mutates further. The third condition for the survival of the virus is that it must acquire a sufficient and stable robust character.

　　　“The danger of infection grows dramatically if one inhales a large amount of the virus at close range,” continues Tashiro. “However, the virus is still fragile at this point, and it significantly loses its infectious power beyond a certain distance from the human body.”

　　　Tashiro stresses N7N9 has yet to obtain this necessary “robust character.” And yet he notes this does not mean human-to-human transmission has not taken place.

　　　On April 24, a Taiwanese businessman just back from China was found to be infected. Because he had not come in contact with live birds while in China, it was a case which indicated the possibility of infection as a result of human-to-human transmission.

　　　In addition, there are several cases in which more than one patient has been found in the same family, raising the possibility of human-to-human infection. While admitting that the possibility of human-to-human infection cannot be denied on the basis of such cases, Tashiro still remains cautious about declaring that human-to-human infection has already happened. Even so, he continues, the statistics available of the recent epidemic are puzzling, explaining:

Possibility of Another Host to H7N9 ?

　　　“There are an estimated 600 billion birds across China. According to the latest information from China, the authorities have examined only 70,000 of those birds. Only 40 of them have been found to be infected with H7N9 – a surprisingly small number. If these birds actually were the cause of the infection this time, it certainly is hard to understand how the disease could have spread in  such a short span of time, resulting in 100 patients found across such an expansive area – including Beijing and Shanghai as well as eight provinces: Zhejiang, Jiangsu, Jiangxi, Anhui, Henan, Shandong, Fujian, and Hunan.

　　　In other words, Tashiro suspects birds may not be the only source of the infection, pointing out the possibility of another host having played a part as the virus was transmitted from birds to humans. Specifically, he warns of the possible danger of other mammals – for instance pigs, or small animals such as  dogs, cats, and mice – constituting additional sources of infection. Tashiro feels strongly that the current method of paying exclusive attention to birds must by all means be modified.

　　　In addition to H7N9, Tashiro identifies H5N1, a virus that spread globally in 2003, as another deadly enemy mankind must prepare itself to face.

　　　“While H5N1 has remained totally unreported in Japan, I wish to emphasize that it is truly a very serious problem. What will happen if these viruses go on multiplying among birds, eventually spreading to humans as they have in the past? We will have no choice but wage a two-front war – against H7N9, which primarily affects seniors, and against H5N1, which harms those under 40. If such a situation develops all at the same time, we will really be at the end of our tether.”

　　　The first vital step towards efficient crisis management is to imagine the worst case scenario. If we adopt resolute measures on top of that, it is highly possible to avoid a crisis. In the case of bird flu, it obviously is impossible to try and prevent it from coming to Japan. So we must act on the assumption that it already is here. That is why Tashiro stresses that early treatment is the main pillar of crisis management. Tamiflu and Relenza – drugs considered reasonably effective in combating these types of virus – must be administered at an early stage.

　　　For now, Japan appears to be fairly well equipped to combat the virus, with a sufficient supply of these drugs in the country. Urgently needed, however, is creation of a new system under which swift action can be taken, making possible the speedy distribution of these drugs the minute the symptoms of a possible epidemic are discerned.

(Translated from “Renaissance Japan” column no. 557 in the May 16, 2013 issue of The Weekly Shincho)