Disease detectives

There are many diseases we know about and understand the causes of. However, sometimes there are outbreaks of a disease that are unexpected and nobody understands why so many people are getting sick.

Today, I’m going to discuss two case studies, one in Senegal, in West Africa, and the other in Guam关岛, an island in the Pacific Ocean. In both places, there were epidemics affecting many people. Researchers had to investigate the causes of these epidemics.

The first situation, in Senegal, concerns a disease called schistosomiasis血吸虫病. Schistosomiasis is caused by a parasite released into rivers by freshwater snails. When anyone comes into contact with the river, the parasite is transmitted to their skin, causing fevers, coughs, stomach pains, and general sickness全身不适.

Although schistosomiasis is one of the most common diseases from a parasite in the world, no one in this part of Senegal had had it before 1986 – the year the Diama Dam was built on the Senegal River. Soon after the dam was built, people started to become ill. In fact, by 1988, 90% of the population had come down with the disease. Finding a solution to this health crisis became critical. After a lot of research, scientists traced the problem back to the dam. This is what they found.

Before the dam was built, there were a lot of prawns in the Senegal River. The prawns ate the freshwater snails that lived in the river, and there was no disease. However, the construction of the dam caused the water in the river to flow differently. This, in turn, changed the prawns’ natural habitat, and eventually led to their extinction. With no natural predators捕食者 left in the river, the snail population increased rapidly. More snails led to more parasites in the river water, and suddenly many people started to become very ill.

A group of researchers called “Project Crevette青虾” decided that the best way to eliminate the disease was to restore the environmental conditions of the river so the prawns would be able to live there again. If the prawns returned to the river, they would eat the snails. This would mean fewer parasites in the river and ultimately less disease. This approach to solving a health problem is significant because it focuses on the main cause of the disease rather than simply giving people medicine to treat the disease.

Now, let’s look at a case study in Guam – a small island in the Pacific Ocean. In the late 1940s, the local people – known as the Chamorro查莫罗人 – contracted感染 a neurological神经系统的 disease called lytico-bodig溶解体病（肌萎缩侧索硬化-帕金森-痴呆）. As the disease only seemed to affect the Chamorro, scientists argued that something in their diet must be the cause.

Every day, the Chamorro made bread using the seeds of the cycad苏铁 plant. These seeds were known to contain a toxin, so researchers initially thought that the flour must be the cause of the epidemic. However, the seeds were washed several times before they were used and this removed most of the toxins, meaning that the flour couldn’t have caused the disease.

At this point, the researchers discovered two interesting facts – more men had the disease than women, and men ate more meat than women. The most commonly eaten meat in the area was the flying fox, and the flying fox regularly ate the seeds of the cycad plant. This meant that there was a high concentration of toxins in the meat of the flying fox, and this fact led researchers to suspect that the meat may have been the cause of the epidemic. Later, they learned that when the flying fox population declined due to overhunting, the incidence of lytico-bodig also started to decrease, and this confirmed that flying fox meat was the cause of the epidemic.

So these are just two examples of the various factors that need to be taken into account when investigating an unusual incidence of a disease. Personally, I think they are quite interesting case studies because they demonstrate that while researching diseases can be challenging, it’s also incredibly rewarding.

Traditional Chinese Medicine

During its long history, Traditional Chinese Medicine (TCM) developed unique views on life, on fitness, and on the prevention and treatment of diseases. The famous TCM practitioner Bian Que, who treated people during the Spring and Autumn, and Warring States Periods, was once asked to compare his medical skills with those of his two elder brothers. Bian Que readily admitted he was the least skilled. His eldest brother could treat a disease before it broke out, Bian Que said, because this brother taught people to adjust their diet, exercise, and balance work and rest so that diseases would be nipped in the bud(将…扼杀在萌芽状态；防患于未然). His second brother could heal a disease when its symptoms were mild whereas Bian Que could only treat patients when their conditions became life-threatening. Because people saw Bian Que using acupuncture(针灸), applying strong medicine to wounds and sometimes performing major surgeries, they assumed he was the best among the three brothers. However, a great doctor is one who is not only skilled in treating diseases but, more importantly, good at preventing them. As Bian Que’s story tells us, “Great physicians treat before illness occurs.” (上工治未病。) This is what TCM has always emphasized. Then, how can we prevent diseases from happening?

Balance between yin and yang

According to TCM, the way to prevent a disease is to follow nature and maintain an inner yin-yang balance. Yin and yang are philosophical concepts dating back to ancient China. Yin is characterized as an inward energy that is feminine, inactive, dark and negative, while yang is characterized as an outward energy that is masculine, active, bright and positive. The whole universe, including human bodies, is in a dynamic balance between these two opposing yet mutually waxing and waning forces（相互对立又相互消长的力量）. When a person is afraid of coldness, for instance, the yin state may dominate in the body; when a person tends to feel hot, yang might be dominant. In an ideal state, yin and yang are perfectly balanced inside the human body. However, external factors such as heat or humidity and internal factors like sorrow or anxiety can disturb this balance, leading to different kinds of discomfort and disease. TCM diagnosis and treatment involve identifying factors that cause imbalance and attempting to bring the human body back into harmony.

Application of TCM treatment

TCM treatment involves a broad range of practices including herbal medicine（草药）, acupuncture（针灸）, tuina (massage推拿), cupping（拔罐）, and dietary therapies（饮食疗法）. Nowadays TCM treatment is not only popular among Chinese but has also gained international recognition. In 2015, Tu Youyou, a Chinese female scientist, was awarded the Nobel Prize in Physiology or Medicine for her discovery of artemisinin（青蒿素）. As an antimalarial drug（抗疟药）, artemisinin subsequently saved millions of lives, especially in developing countries. It is extracted from the medicinal herb（药用植物） called qinghao used by Chinese doctors for a long time to treat fever and diarrhea（腹泻）. Other TCM methods are also going global and have been extensively used to alleviate（缓解） pain and cure chronic diseases（慢性病）. For instance, at the 2016 Summer Olympics, some foreign athletes were seen with purple spots on their skin from cupping. Acupuncture has gained global popularity for its remarkable effects in treating back and joint pain. TCM has spread to over a hundred countries and regions. We can expect that as more is understood about this ancient branch of medicine, TCM will have more to offer to the well-being of mankind.