One of the factors in the loss against the current outbreak of Ebola virus (EBOV) is cultural disparity. In the ancient days of Japan, when knowledge of modern medicine was lacking, people would pray to the gods against infectious disease, and many historical shrine activities arose from such diseases. Historical descriptions of smallpox eradication may help to overcome differences in civilization.
The history of smallpox vaccination dates to 1796, when Edward Jenner demonstrated the resistance of inoculated individuals to smallpox. Description of smallpox was found from AD 735 at Kyushu in Japan, and even the emperor suffered from the disease. Masamune Date Tohoku Shogun (1567-1634) also suffered from smallpox and lost his left eye. Japan closed the door to the rest of the world from 1639 and prohibited trading with any foreign countries except China and Holland. The isolation brought peace for 300 years, except that syphilis had already entered Japan around 1520 and was endemic in large cities. The national isolation, however, delayed nationwide Jennerian vaccination until 1849 when a German doctor, Dr. Otto Mohnike, successfully vaccinated one child in Nagasaki, Japan.Reference Matsuki1 In 1854 Japan concluded a commercial treaty with the United States, and modern civilization including knowledge of medical science proceeded as a result of the Meiji revolution. The Compulsory Vaccination Act was passed in 1886 in Japan.
The first compulsory mass vaccination was performed in 1857 among the Ainu people in Hokkaido, who are regarded as descendants of the pre-agriculture native population of northern Japan, because they had suffered periodically from serious epidemics of smallpox. More than 6000 Ainu people were successfully vaccinated, and the ongoing population decrease of the Ainu was terminated.Reference Takashita2, Reference Ogata and Sen3 This event was painted as a memorial representing successful vaccination and was given to the local government 150 years ago. The description attached reads that the Ainu people feared vaccination and some fled into the mountains. Therefore, the government gave rice, clothes, and money to encourage acceptance of the vaccination, as shown in the picture (Figure 1). The picture also shows two doctors performing vaccinations by using lancets. This picture also implies that any intervention against microorganisms should be conducted carefully for human security, even though great beneficial effects can be anticipated for society.Reference Matsuki1
Vaccination of Ainos. Painted by Byozan Hirasawa (1822-1876)
Through similar such efforts, the World Health Organization declared the eradication of smallpox worldwide in 1980, 1 year before the human immunodeficiency virus (HIV) endemic started.Reference Hedstrom4 Coincidentally, the Ainu people’s infection with human T cell leukemia virus (HTLV)-1 was also known.Reference Ishida, Yamamoto and Omoto5 This extraordinary achievement was accomplished through the collaboration of countries around the world. The success is partly because smallpox infection is not a zoonosis. EBOV is a zoonotic pathogen carried by various species of fruit bats and monkeys that are present throughout central and sub-Saharan Africa. We should also prevent the infection of EBOV to animals in our country from imported cases.
PATHOGENESIS OF EBOV AND OTHER HEMORRHAGIC VIRUSES
Because disease containment during outbreaks is the first priority, it has been difficult to study the pathogenesis of human EBOV infection. In a study of EBOV-infected monkeys, an increase in D-dimer was observed after 24 hours and 2 days later, while activation of protein C was decreased. This phenomenon is due to a reduction in coagulation proteins associated with liver failure caused by viral infection. The platelets did not decrease until 3 to 4 days.Reference Bray6 To quickly determine a patient’s disease state, it is important to monitor changes in the coagulation system. Such reactions can also occur in other infections. However, the severe symptoms of Ebola virus disease (EVD) are presumably due to the specific mechanism of the infection. According to a study by Takada et al in Hokkaido University,Reference Takada, Feldmann, Ksiazek and Kawaoka7 the mechanism in many organs of the body is the presence of antibodies to EBOV surface glycoprotein, which enhances the infectivity of the virus by crosslinking cells and glycoproteins via the Fc receptor or the complement component C1q/C1q receptor complex on the cell surface. This mechanism is a new concept of an antibody-dependent infection enhancement.
A few studies using Luminex have been reported, and the first report showed a “cytokine storm,” with hypersecretion of numerous pro-inflammatory cytokines, chemokines, and growth factors and the noteworthy absence of antiviral interferon (IFN)-α2. Immunosuppression was characterized by very low levels of circulating cytokines produced by T lymphocytes and by massive loss of peripheral CD4 and CD8 lymphocytes, probably through Fas/FasL-mediated apoptosis.Reference Wauquier, Becquart and Padilla8 In contrast, another study showed low levels of pro-inflammatory cytokines and high levels of immunosuppressive cytokines like interleukin (IL)-10.Reference Gupta, MacNeil and Reed9
Molecular pathogenesis in similar symptoms caused by other viruses could give a clue to the pathogenesis of EVD. In the infection of dengue virus (DENV), another hemorrhagic virus, IL-10 followed by IFNγ-induced protein-10 (IP-10), IL-18, and Galectin-9 (Gal-9), a matricellular protein (MCP) were remarkably enhanced.Reference Chagan-Yasutan, Ndhlovu and Lacuesta10 Gal-9 is reported to be produced by both T and endothelial cells and is recognized as a bidirectional immunoregulator. We also reported a marked elevation of Gal-9 in acute HIV infection and a rapid decrease after anti-retroviral therapy. Gal-9 could be a potential danger signal biomarker of acute virus infection.Reference Saitoh, Ashino and Chagan-Yasutan11 In an animal model of EBOV infection, immunosuppression, increased vascular permeability, and impaired coagulation have been identified as hallmarks of the disease. Gal-9 is also known to induce apoptosis of Th1 cells and may contribute to the apoptosis of T cells in EVD.
We believe MCPs may play a primary recovery function of virus infection because all infection and inflammation are associated with edema, in which the accumulated fluid is rich in MCPs. In addition to Gal-9, we have examined if another MCP, osteopontin (OPN), is involved in acute virus infection. Proteolytic cleavage of OPN by thrombin (between Arg168 and Ser169) generates a functional fragment of N-terminal OPN (trOPN). In DENV infection, plasma leakage associated with mild thrombocytopenia is frequently observed in dengue shock syndrome under fatal conditions. The levels of OPN, trOPN, d-dimer, thrombin-antithrombin complex (TAT) protein, and thrombomodulin (TM) are significantly elevated in the critical phase in both dengue fever (DF) and dengue hemorrhagic fever (DHF) patients as compared to healthy individuals. During the recovery phase, OPN levels declined whereas trOPN levels further increased dramatically in both DF and DHF. The OPN level was found to directly correlate with d-dimer and ferritin levels, whereas the generation of trOPN was positively associated with the TAT level, platelet count, and viral RNA load.Reference Chagan-Yasutan, Lacuesta and Ndhlovu12 These findings indicate that OPN and trOPN could reflect immuno-coagulation cross talk and high trOPN levels could reflect recovery. Studies of the roles of MCPs in inflammation and coagulation abnormalities in DENV or HIV infection would help to elucidate the pathogenesis of EVD.
INFECTION PREVENTION AND INFECTION ROUTE
The source of infection of EBOV is direct contact with blood, saliva, sweat, secretions, or excretions from patients with symptoms. Patients with symptoms that have disappeared and patients who have died can still transmit infection. Because EBOV is only transmitted by contact with body fluids, further infection is suppressed by thorough precautions such as wearing gloves and gowns when touching the infected person. For infection control, the following are important in preventing transmission:13 1) hand hygiene, 2) use of personal protective equipment (PPE; e.g., gloves, gowns, masks), 3) safe injection practices, 4) safe handling of potentially contaminated equipment or surfaces in the patient environment, and 5) respiratory hygiene/cough etiquette.
HANDLING OF PATIENTS IN JAPAN
There has been time to carefully consider the response in Japan, which lies 14,000 kilometers from West Africa and has no direct flights from the affected area and no EBOV generation in neighboring countries. However, in this era of global transportation, we must establish a system that can handle suspicious travelers with fever from endemic countries who passed the first check at the international port or airports. In the Japanese Act Regarding Infectious Disease, EBOV is classified as a type I infectious disease (http://www.mhlw.go.jp/english/wp/wp-hw3/dl/2-083.pdf). As of April 2014, there are 44 hospitals (84 beds) throughout Japan that have designated beds for class I infectious diseases.
Correct diagnostic processes and appropriate precaution and isolation to prevent outbreak are vital. Interviews with patients with fevers >38 °C are critical. We first ask immigrants and returnees whether more than 21 days have passed since they left the countries where EVD is prevalent (Guinea, Liberia, Sierra Leone, Nigeria, Democratic Republic of the Congo, Uganda, Sudan, Gabon, Cote d'Ivoire, Republic of Congo, and Senegal). If only fever is present, they are observed as an inpatient or outpatient. The differential diagnosis includes malaria, typhoid fever, shigellosis, cholera, leptospirosis, plague, rickettsial disease, relapsing fever, meningitis, hepatitis, and other viral hemorrhagic fevers. In the case of continued fever, intense weakness, muscle pain, headache, sore throat, vomiting, diarrhea, rash, kidney failure, liver dysfunction, external or internal bleeding with a decrease in white blood cells and platelets, or an elevation of liver enzymes, we proceed to the next step.
Patients are transported to medical institutions designated for class I or class II infectious diseases as suspect cases designated EVD. Class I and class II infectious diseases are defined in the Prevention of Infectious Diseases and Medical Care for Infectious Patients Act. Class I corresponds to Centers for Disease Control and Prevention category A and includes pathogens that have a “very serious” influence on the health and life of people (matching). Class II includes pathogens that have a “serious” impact on the health and life of people. Samples of blood or tissue from patients should be sent to the National Institute of Infectious Diseases for a definitive diagnosis. Samples are an extreme biohazard risk; laboratory testing on non-inactivated samples should be conducted under maximum biological containment conditions. Similar measures are taken with a person who is in contact with the body fluids of a person or animal diagnosed with EVD or suspected to have EVD.
After in-hospital diagnosis of temporarily suspected cases, sending the patient to the medical institution designated for class I is virtually impossible because transportation of the patient increases the probability of spread of the infection. Patients will be placed in isolation and medically treated at the hospital that performed the first medical examination even if it is not a designated hospital. Thus, in all hospitals, it is always necessary to conduct measures to control communicable diseases. It is necessary to determine the hospital policy for handling patients suspected of having class I or class II infectious diseases. For proper medical treatment, the instruments for biochemical and coagulation tests are required in the patient’s room, which must properly handle drainage for class I infection, and a designated X-ray machine in the hospital ward is also necessary. Standard and contact precautions and appropriate sterilization of the instruments will sufficiently prevent nosocomial infection and outbreak.
TREATMENT
Patients are given only symptomatic treatment without antiviral agents, because we do not have any effective antiviral medicine at present. The three classifications of disseminated intravascular coagulation (DIC) that must be attended to in EVD are fibrinolytic system suppression, fibrinolysis balance, and hyperfibrinolysis. EVD is presumed to target the hyperfibrinolysis type. For coagulation therapy, the serine protease inhibitor and antithrombin III is preferred over other forms of anticoagulant therapy. If necessary, a transfusion of platelet concentrate or fresh frozen plasma may be considered. Recombinant thrombomodulin (TM) forms a thrombin-TM complex and suppresses thrombin. Protein C (APC) is activated by a thrombin-TM complex and inhibits thrombin generation under protein S.Reference Ito and Maruyama14 APC also promotes the activation of thrombin-activatable fibrinolysis inhibitor (TAFI) and exerts anti-fibrolytic activity. APC exerts anti-inflammatory effects by binding to protease-activated receptor (PAR)-1. A thrombin-TM complex suppresses inflammation directly by adsorbing high mobility group box (HMBG)-1 released from necrotic cells, activated by macrophages.Reference Moll, Lindley and Pescatore15 It is important to know that bleeding and DIC in EVD can be controlled by using these medicines.
The product ZMapp is a combination of three different monoclonal antibodies that bind to the protein of EBOV. It is too early to conclude whether ZMapp is safe and effective because it is still in the experimental stage and has not yet been tested in humans as a clinical trial.16 The establishment of careful outcome-based evidence is required.
Acknowledgment
We are grateful to Hokkaido University Library for permission of publication of the picture of vaccination of Ainos.
