Beating an ancient illness
China defeats deadly waterborne disease that once took a toll on the rural population living along the Yangtze River
Many people enjoy running or strolling along the picturesque banks of the Yangtze River in Nanjing’s Pukou district, drawn by spacious areas, greenery, countless willow trees and fresh breeze.
However, those who want to swim or wade in the river will be stopped by Yang Wenrong and his colleagues.
A member of the district’s control center for schistosomiasis, a disease caused by parasitic worms, Yang’s daily work involves patrolling the river banks to prevent people becoming infected.
Known in China as “blood-sucking” worms, these parasites can penetrate the skin within 10 seconds.
Yang said: “Many people like to play in the water, but this is not safe on many stretches of the Yangtze. Contact with the water should be avoided, especially on warm and hot days. Even those who have to work in the river, such as flood control employees, must wear protective clothing and rubber gloves.”
Schistosomiasis, which infects humans and animals, can cause fever, diarrhea and enlarged livers, among other conditions. Without proper treatment, it may result in death.
The worms lay eggs inside the body, which are later excreted. Those that come into contact with water hatch into larvae known as miracidia, which later invade its sole intermediate hosts, oncomelania — freshwater snails — before developing into cercariae, a free-swimming larva.
Upon contact with water containing cercariae, humans and animals are infected with schistosomiasis. The parasites will continue to produce numerous eggs, harming the liver and spleen.
Patients with the disease experience distended stomachs, as they accumulate fluid in the peritoneal cavity, the fluid-filled gap between the walls of the abdomen and internal organs. In advanced cases, infected women become infertile and children experience dwarfism — short stature resulting from a genetic or medical condition.
Chinese have been battling the disease for more than 2,000 years. In 1971, in Changsha, Hunan province, the body of a female was unearthed at a tomb from the Western Han Dynasty (206 BC-AD 24). Scientists later found the eggs of a parasitic flatworm known as a schistosome in the body.
In 1905, schistosome eggs were found in the feces of a farmer in Changde county, Hunan province — the first confirmed case of schistosomiasis in China.
Before the 1950s, the disease was prevalent in 350 counties across 12 provinces and municipalities in China, including Shanghai, Jiangsu and Zhejiang. More than 10 million were infected and over 100 million were exposed to it.
The People’s Republic of China first battled the disease in 1949, the year it was founded.
In May that year, after the PLA liberated Shanghai, the ninth corps of the Third Field Army stationed in Shanghai’s Songjiang and Jiading suburbs were training for the battle to liberate Taiwan.
However, after training in water, many of the 100,000 troops became sick and developed rashes, fever and diarrhea from schistosomiasis infection.
Aided by a researcher from the United Kingdom, a schistosomiasis control committee was quickly established in suburban Shanghai. In December 1949, more than 2,000 medical workers and students from the city’s hospitals and medical colleges joined the committee to treat the soldiers.
According to the Jiangsu Institute of Parasitic Diseases, in the 1950s, the province had more than 2.53 million schistosomiasis patients. Five of 10 counties with the most serious infections nationwide were in Jiangsu.
Back then, the disease wiped out entire populations of several villages in Kunshan, a county in Suzhou. In 1955, 85.5 percent of young men undergoing medical checkups for military conscription were found to be infected with schistosomiasis. In 1956, the county was exempted from military duty for seven consecutive years.
In Xinming village, Gaoyou county, Jiangsu, in 1950, a total of 4,019 of its 5,257 residents were infected, with 1,335 dying in less than six months.
For two decades from 1950, Rentun village in Shanghai was known as a “ghost village” — half the population had died from the disease. It claimed all the members of 121 families and infected 97 percent of 461 previously healthy people. No babies were born there for more than seven years.
In 1953, Shen Junru, the first president of the Supreme People’s Court, wrote to Chairman Mao Zedong about the prevalence of schistosomiasis in provinces on the lower reaches of the Yangtze River. A systematic and effective national battle was then launched against the disease.
A central prevention and control team, led by Ke Qingshi, the Shanghai Party secretary, was formed in 1955. Numerous teams were later established in counties, cities and provinces
to treat patients and control the disease.
In Wuxi, Jiangsu province, many medical workers have devoted their lives to preventing and controlling schistosomiasis, said Li Wei, a director at the Jiangsu Institute of Parasitic Diseases.
“This work has not been easy. The workers have been sent to remote areas, educating the locals and working with them to eliminate schistosome. In the 1960s, some 60 percent of researchers from the institute were sent to Kunshan. They spent at least six months there every year,” Li said.
“In the 1970s, researchers were sent to cities along the Yangtze to work with farmers to eliminate oncomelania on the river beaches. Inevitably, after many hours in the water, they became infected with schistosomiasis, but they went back into the water after receiving treatment.”
Medical workers initially focused on saving critically ill patients. However, the medicine used back then, although effective for treating schistosomiasis, could also affect heart function.
With researchers’ efforts, more effective and safer drugs were developed, allowing surgeons to tend to patients in critical condition.
The disease now can be cured in three days with the synthetic drug praziquantel.
Preventing feces containing schistosome eggs from entering the water was central to preventing the disease. Back then, many toilets in rural areas were not hygienic and feces were used to fertilize crops. The eggs could easily spread and pollute soil and water.
Medical workers spoke with farmers, asking them not to wash in rivers or use feces as fertilizers. They set up hygienic toilets, told them not to drink unpurified water and built special ponds to provide livestock with safe water supplies.
For farmers who had to grow rice or use river water for washing, the researchers made protective coverings to prevent cercariae from penetrating the skin.
Eliminating oncomelania was also crucial, but the freshwater snails quickly multiplied in provinces and municipalities in East and South China.
Medical workers in infected areas combed through all the rivers, ponds and lakes to detect oncomelania — a seemingly impossible task.
They drugged the snails, built stone and cement river banks to prevent them from entering the water and buried them in dry soil. After being buried for three months, the number of snails had fallen nearly 75 percent.
After decades of hard work, remarkable progress was made in many areas. In 1985, Shanghai announced that schistosomiasis had been eradicated in the city. The number of patients nationwide fell from more than 11 million in the 1950s to 840,000 in 2004.
In Jiangsu, the last two cows with schistosomiasis were discovered in 2007, the final acute case was reported in 2008, and the last positive case resulting from a stool examination was reported in 2012, according to the Jiangsu Institute of Parasitic Diseases.
In 2018, data from the national schistosomiasis prevention and control system and 453 national surveillance sites for the disease showed significant progress in five of 12 vulnerable provinces and municipalities. Six provinces had controlled transmission of the disease, and the transmission chain was successfully broken in Sichuan.
That year, no cases of acute schistosomiasis cases were reported in China.
With their experience in preventing and controlling the disease, Chinese
medical workers have contacted other countries troubled by infections.
Schistosomiasis is prevalent in 78 countries and regions worldwide, with 85 percent of these in sub-Saharan Africa.
Zhu Guoding, a director of the Jiangsu Institute of Parasitic Diseases, said it has held 59 courses to train 1,718 medical professionals from 71 developing countries in Asia, Africa and Latin America.
“In 2017, we participated in the China-Zanzibar schistosomiasis control and elimination project to help local people fight the disease. This was China’s first public health program overseas,” he said.
In 2013 and 2014, experts from the World Health Organization and China visited Zanzibar several times to assess the project’s feasibility.
A memorandum of understanding on jointly controlling the disease was signed by the three sides in 2014. Two years later, the Jiangsu institute undertook the mission.
“During the following three years, six groups of Chinese experts worked in Zanzibar, sharing their experience with local doctors and residents,” Zhu said.
“We held lectures for local medical workers, provided medicine and worked with many government organizations to improve awareness of schistosomiasis prevention.”
In three years, the schistosomiasis infection rate on Pemba Island, Zanzibar, fell from 8.92 percent to 0.64 percent, Zhu said.
“Our work was highly praised by the WHO, and the president of Zanzibar asked us for further cooperation in controlling the disease,” he added.
“We also offer medical services to some countries taking part in the Belt and Road Initiative to help local people and Chinese working in these nations.”