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Navigating the tropical disease's mysteries

Dengue returned to Japan in 2014 after a 70-year absence. Kouichi Morita—who has educated Japan’s populace in basic dengue prevention—describes key turning points in his unique career, the persistent mysteries of the disease, and the scientific and social complexities in the quest to prevent and treat it.

Unexpectedly Large-Scale Outbreak in Japan in Summer 2014

Dengue, which has been expanding globally, drew attention in Japan in August 2014 when an outbreak originating in Yoyogi Park in Tokyo resulted in the infection of more than 150 people in just a few weeks. Morita describes the global upsurge in the disease: “In the past few years, over 200 people had been infected annually while traveling abroad, and two years ago a German woman was thought to have been infected in Japan. We were concerned about a potential outbreak in Japan?but in fact, it was larger than we expected.”

As dengue rose in public attention, so did the call for Morita’s expertise. He became a public spokesperson and advocate for protection against the disease, especially during summer, when the Asian bush mosquitoes that transmit the virus are most active: “We should be careful not to be bitten by mosquitoes, especially in crowded places, in order to protect ourselves and others.” His voice has been essential in educating Japan’s populace in basic preventive measures.

Scenes of Field Hospitals from His Time as a Young Researcher in Thailand

The Nagasaki University School of Medicine has a long history. The School was established during the end of the Edo Period in 1857 as a “medical learning center” that helped spread knowledge of modern Western medicine to Japan. The Institute of Tropical Medicine, or “Nekken,” in which Morita serves as dean, is the only research facility in Japan that specializes in tropical diseases. In the 73 years since the founding of its predecessor, the East Asia Research Institute of Endemics, Nekken has contributed to eliminating filariasis and schistosomiasis in Japan and combating infectious diseases in tropical areas. The institute also enthusiastically participates in international medical support activities and was featured in The Lion Standing in the Wind, a film about a dedicated Japanese medical doctor in Africa.

Morita, who always wanted to be a researcher, “just so happened” to enroll in a lab led by Akira Igarashi (professor emeritus) at Nekken when he was a graduate student. Igarashi was a leader in dengue research who successfully cultivated the dengue virus by using mosquito cells in his laboratory. While conducting research in Thailand as Igarashi’s assistant, Morita saw something he would never forget: “Dengue was rampant all over Thailand at the time. I went to a rural hospital, and there were 30 beds lined up with children suffering from dengue hemorrhagic fever. There were two or three children in each bed, with nurses rushing busily between them... It was just like a field hospital.”

What Causes a Condition to Become Serious? Theories, But No Answers

Isolating the dengue virus with local staff at the Busia branch of the Kenya Medical Research Institute (on the border of Kenya and Uganda)

Today, Morita leads a research team of 20 people and travels between Nagasaki, Kenya, and Vietnam. Through Nekken, he collaborates with private corporations and research agencies, both domestically and abroad, researching a broad array of mosquito-borne viruses, including the chikungunya virus, the West Nile virus, and yellow fever.

But dengue, “the most dangerous to humans of them all,” remains a special concern. In many cases, the first infection simply leads to a minor illness that can be overcome with rest, but if a person becomes re-infected, the disease can become serious and lead to death. What are the virulence factors? Why does the condition become so serious? Despite many hypotheses, there are no definitive answers. Strains of the virus, notes Morita, can differ widely; “Some are transmitted easily to human cells, while others multiply easily within mosquito cells. We think that this difference may have something to do with the illness becoming more severe, but we do not know what contributes to what.” And finding the answer is difficult, in part because experiments cannot be conducted on animals. “Dengue can only be transmitted among humans. Scientists have tried using monkeys and rats, to no avail.” That is why he has begun working with other researchers to create an experimental animal model.

Scientific Barriers in the Lab, Social Barriers on the Ground

Barriers to progress can be both scientific and social. “Sometimes the bacterial expression system to make a diagnostic drug doesn’t function properly, or we have to wait because of unsafe conditions in the field, or we can’t go to Kenya’s border with Somalia because there are guerilla insurgents there. If you come from a different country or religion, some people won’t let you take even a small blood sample.” When asked how he overcomes this, Morita gives a friendly smile: “The only choice is to talk with local people and do our best to find a solution. There is no silver bullet. If you find one, let me know.”

As a leader, he focuses on “not getting in the way of the younger generation.” He listens to the ideas of young people who are studying hard and tries to foster positivity. He encourages experimentation and is careful not to undermine his mentees’ personal drive and motivation, wanting them to experience “the joy of solving science’s mysteries.” His eyes crinkle as he smiles, saying, “Some [of my students] have even found posts for themselves abroad. I’m happy to see them grow into self-reliant researchers.”

Microbes in the Jungle, and a Path toward Coexistence with Man

He describes the ultimate goal of his research as “symbiosis with nature.” “Many tropical diseases lie dormant in jungles. These unknown microbes are like extraterrestrials to humans when we come in contact with them by entering the abundant ecosystems of tropical forests. They don’t intend to do us any harm, and some, such as Bacillus subtillis natto, aid humans. But others?like the Ebola virus?cause sickness. If we can discover the virulence factors or develop a drug for treatment, then they become more manageable. However, we can never get rid of them, as long as there are hosts in the natural world.”

Currently, Morita is engaged in creating rapid diagnostic methods and early warning systems for yellow fever and Rift Valley fever. In addition to developing a kit to detect infectious diseases early on, he is working on ways to use cell phones to share information in real-time between field sites, medical centers, and the Ministry of Health, allowing quick disease intervention. “Instead of fighting infectious diseases, we need to first contain them and make sure that they don’t spread. If this turns out to be successful, we can apply it to other illnesses as well.”

Passing on Lessons That Every Researcher Should Remember

Neglected tropical diseases were included in the official documentation of the G7 Summit in 2015, so we can expect accelerated efforts to address them. Field studies are also needed for the new communicable diseases that continue to emerge every few years. There was a severe acute respiratory syndrome (SARS) outbreak in 2003, when Morita was traveling through Southeast Asia as a World Health Organization (WHO) expert, and in recent years, new pathogens?such as those that cause severe fever with thrombocytopenia Syndrome (SFTS), Middle East respiratory syndrome (MERS), and pandemic influenza?have been discovered. “These diseases will always be a problem in this natural world as long as we are living on this planet; they are not going to go away any time soon.” Morita is prepared for a long journey.

There is a saying at Nekken: “The bench is in the bush.” The bench refers to the laboratory, and the bush refers to the field. As Morita says, “It is important to go to the area where the disease has broken out, instead of staying locked up in a lab all the time. There are some things you only notice in the field. I hope everyone here at Nekken remembers that.”

Research on Dengue Fever and Other Tropical Diseases

Kouichi Morita

Born in Ehime Prefecture in 1956, Morita received a PhD from the Nagasaki University School of Medicine. He specializes in viruses. He served as an assistant instructor at the New Jersey Medical School (USA), head of the Division of Combating Communicable Diseases at the Western Pacific Region office of the WHO, and professor at the Institute of Tropical Diseases at Nagasaki University. He began in his current position as dean in 2013, the same year he received an award from the Japanese Society of Tropical Medicine. His specialty is finding ways to control infectious diseases, such as dengue, that affect large areas, mainly in Asia and Africa.

Image of Kouichi Morita

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