What is Hantavirus Pulmonary Syndrome?

Hantavirus infection was noted in Japan in the mid-1970s when a series of patients with unknown fever occurred among rat handlers at medical animal experimental facilities in various locations, and the etiology was unknown at that time. (The outbreak continued until 1984, a total of 127 cases, one of which died). Earlier, in the 1960s, an unknown fever was reported in a poorly lived area in Umeda, Osaka (two of 119 cases died). Before the war, there was an epidemic in the Amur River basin that flows along the border between China and the Soviet Union. Was done. Subsequently, during the Korean War, about 3,200 unknown fever cases were reported between UN forces and received considerable attention. Lee et al. Of the Korea Korea University in 1976 first isolated the pathogenic virus from an endemic gerbil (Apodemus) and named it the Hantaan virus after the river where the gerbil was captured. The above-mentioned diseases are caused by a group of Hunan virus and cause hemorrhagic fever with renal symptoms. In Japan, the causative virus was isolated for the first time in Japan in 1982 by the Institute for Infectious Diseases and Hokkaido University School of Veterinary Medicine from rats at Sapporo Medical University. With subsequent progress in research, the fifth new genus of the Bunyaviridae family has named the Hantavirus genus. In the United States, Guide Yusek et al. Showed that the virus was retained among the voles (Microtus). However, although zoologists and others recognized the presence of the antibody, its pathogenicity to humans was unknown, so it was considered a problem. Had not been. However, in 1993, several deaths were reported among Navajo Indians in the southwestern United States due to acute dyspnea with pulmonary edema. The disease manifested as acute respiratory symptoms without renal symptoms and about 50% death, the first occurrence of the problematic Hantavirus Pulmonary Syndrome (HPS). Since 1995, reports of HPS have been reported from South America one after another.

Epidemiology

Many viruses of the Bunyaviridae family are arthropod-borne (Crimean-congo hemorrhagic fever virus, tick-borne), but hantaviruses are characterized by murine transmission. Many are transmitted by inhaling the virus as an aerosol from fresh or dry feces and urine. It can also occur by touching the nose, eyes, or mouth through a rat bite or a mouse touch.

Hantavirus causing HFRS is widely distributed in Eurasia. The major one is a human virus hosting in the Session gerbil (Apodemus agrarius) found on the Korean Peninsula, northern to central China and Far Eastern Russia. There are tens of thousands of cases annually in China, thousands in Russia, and hundreds in South Korea. It is the Seoul virus that is widely held worldwide by rat rats (Rattus norvegicus) and has not been reported in Japan since the 1984 laboratory case. Rats in harbor areas of Japan still carry the virus today. Attention should be paid to the fact that no cases have been reported.

The HPS virus in the southwestern United States at the beginning was the Sin Nombre virus, and the mice carrying it are deer (deer) mice and (Peromyscus maniculatus). The rat is a popular species widely distributed on the North American continent and abundant. A house is easy to enter. It is also found among a number of rat species, including cotton rats (Table 1).
164 Between 1993 and June 1997, 164 US HPS cases were reported in 28 states. Four corners in the southwestern United States (these four states are the only ones in contact) had 29 New Mexico, 22 Arizona, 11 Colorado, and 10 Utah. The average age was 36 years, 99 males, 121 whites, and 38 American Indians. The fatality rate was 47%, which was extremely high. The cumulative total from 1993 to March 2000 was 238, with an average age of 37, 144 males, 183 whites, 49 American Indians, and a 42% fatality rate. A retrospective study suggests that it had already occurred at least in 1959.
In Canada, mainly in Alberta, it occurs frequently in the western part. There were 32 cases between 1994 and 1999, of which 12 (38%) died. The average age is 39 years and 19 males (60%). In 1995, 29 HPS cases were reported in Argentina, South America. In the spring of 1996, 18 cases were reported. The pathogenicity was as strong as the Sin Nombre Virus. There is a virological difference from the Shin Nombre virus, and it has come to be called the Andean virus. The Chilean virus is also an Andean virus. Others have been reported in Brazil, Paraguay, Uruguay, Bolivia, and Central America Panama. At least 191 cases have been reported in Argentina, 15 in Uruguay, 70 in Chile, 34 in Paraguay and 12 in Brazil.
It is thought that there is no human-to-human transmission of hantavirus infection of HFRS or HPS in North America. However, in the case of southern Argentina in September 1996, there were 18 cases of HP’s inhabitants and visitors, and 2 cases of HPS involving patients but not visiting the area, with a mortality rate of 50%. This is an example of human-to-human transmission in a case involving a patient due to inconceivable contact with a mouse. Virological evidence was also presented and became an important issue, but has since ceased and has not recurred, but will continue to require attention.

Pathogen

Depending on the virus of the genus Hantavirus, the Bunyaviridae RNA virus is negative single-stranded and 3 segments. 80-120nm spherical particles with envelope.
The virus has a strong relationship with the host, and the specific virus is retained in the same kind of rat. The HPS virus from deer mice in the southwestern United States was initially called Four Corner Virus or Muerto Canyon Virus but was soon called the Sin Nombre Virus. The HPS virus from Cotton Rat is the Black Creek Canal virus. The HPS virus from Argentine rice rats is called the Andean virus (Table 1).

Clinical symptoms

Characterized by tachypnea, tachycardia, lower back pain, and dyspnea due to bilateral interstitial infiltration of the lungs. The first symptoms are similar to those of a cold, with a cough and a fever of 38 to 40 degrees. Symptoms progress rapidly and dyspnea occurs. Fever, muscle pain, and chills are almost common clinical symptoms observed on admission, and nausea/vomiting, diarrhea and malaise are common, and other short breathing, dizziness, joint pain, back pain, chest pain, abdominal pain, sweating and coughing Yes, with rare rhinorrhea and sore throat. The incubation period is typically two weeks.

Pathogen diagnosis

IgM and IgG antibodies against the HPS virus are measured by the enzyme antibody method and the indirect fluorescent antibody method. Viral antigens present in the tissue are detected using a tissue immunochemical technique. Check the gene sequence of the gene fragment by RT-PCR. Rats should be captured and sampled by implementing aerosol countermeasures. Pathogen handling is at a biosafety level (BSL) of 3 or 4.
When making a diagnosis, be sure to ask if there is any contact with the rat.

Treatment and prevention

Early intensive care is essential for the treatment of HPS patients, and early ventilation is required. Oxygen depletion must be prevented during transportation of the ICU. Oxygen saturation, fluid balance, and blood pressure need to be monitored closely.
Since the natural host of the virus is a mouse, breaking contact with the mouse is a preventive point. Many are transmitted by inhaling fresh or dry feces, urine or saliva. Infection can also occur by touching the nose, eyes or mouth through a rat bite or a mouse touch. Therefore, avoid dust and food contaminated with urine and feces. Cover food for storage. Keep the house and surroundings clean and prevent rat nests. Care should be taken when cleaning huts that have been contaminated with rats without using them for a while. In outdoor activities such as camping, consider rodent control. This virus does not spread through humans, insects, pets or livestock.
? No shrews live in Japan. It is believed that the soul virus, which uses rats as a host, has been brought into Japan from abroad. Similarly, the likelihood of the HPS virus being introduced is undeniable but very low. However, HPS virus infections should be kept in mind. If you are going to the territory of the Americas, you should check local information about HPS and pay particular attention to contact with rats. In the event of an outbreak in Panama, measures were taken to stop the carnival, calling for attention to avoid contact with mice.

About outbreak trend investigation?

Continued outbreaks continue to occur in the reported regions such as the United States and Canada. A new case occurred in Central America in Panama in mid-February this year, killing three out of nine cases. Heading to end but still outbreaks. However, there are still no reports outside the Americas.
In the U.S., the outbreak occurred again this year, and the cumulative total from 1993 to May this year was 31 in 31 states, including 41 in New Mexico, 27 in Arizona, 18 in Colorado, 12 in Utah, 26 in California, and 21 in Washington. There are 250 cases. The situation was almost the same as that described above until June 1997.

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