[Source: Health News Channel]
The eggs or larvae of soil-transmitted nematodes develop in the external environment such as soil and do not require an intermediate host to infect humans directly. Parasitic diseases caused by soil-transmitted nematodes parasitizing the human body are collectively referred to as soil-transmitted nematode diseases.
The National Implementation Plan for the Comprehensive Control of Key Parasitic Diseases such as Hydatid Disease (2024-2030) proposes that by 2025 and 2030, the infection rate of soil-transmitted nematodes in key endemic provinces will be reduced by more than 10% and 30%, respectively. Over the course of many years of comprehensive prevention and control, some localities have made explorations and formed experiences. In Chongqing, due to the climate and special geographical environment, soil-transmitted nematode disease was once epidemic and affected the health of the public. Recently, the reporter came to the Chongqing Municipal Center for Disease Control and Prevention and Yunyang County, Chongqing City, and saw that the prevention and control measures to control the epidemic of soil-transmitted nematode disease here are achieving practical results.
Look for eggs under the microscope
The eggs of fertilized roundworms are short oval or nearly round, the egg shell is thick, double-linear, and covered with a thick and papillary protruding protein membrane, brownish-yellow; Pinworm eggs are semi-oval, asymmetrical, flattened on one side, slightly convex on one side, and persimmon core-shaped...... In the microscopic examination room of the laboratory of the Chongqing Municipal Center for Disease Control and Prevention, the reporter saw the eggs of different soil-transmitted nematodes through a microscope.
There is no need for an intermediate host, and the developmental stage before entering the human body is carried out in the external environment (mainly referring to the soil), and the parasite body morphology is linear...... These are typical features of soil-transmitted nematodes. "Everyone is more familiar with roundworms, hookworms, whipworms, etc. Although pinworms do not develop in soil, they are parasites with a direct life history and can be called soil-transmitted nematodes in epidemiology. Luo Fei, deputy director of the Institute of Endemic and Parasitic Disease Prevention and Control of the Chongqing Municipal Center for Disease Control and Prevention, explained.
Accurately judging whether these parasite eggs are present under the microscope is an important part of laboratory testing, and it is also an important means to investigate the infection rate of soil-transmitted nematode patients. Under the microscope, microscopists mainly rely on the naked eye to find eggs and distinguish the shape, number, and size of parasite eggs - not only to check for soil-transmitted nematodes and other intestinal worm eggs to count the infection rate, but also to determine the degree of infection according to the number of eggs in the specimen.
"Every year, we will select a certain number of districts and counties to carry out population infection surveys." Luo Fei introduced that every time the infection rate survey is carried out, sampling and collection of fecal specimens are carried out within the specified time and range, and the staff of each monitoring point will bring the feces back to the laboratories (laboratory departments) of each township health center, and carry out parasite egg detection under the guidance of technical personnel of CDC at all levels, and the district, county, and municipal CDC laboratories are responsible for reviewing the specimens proportionally.
"Based on the test results, the staff at the surveillance site will direct the infected person who tests positive for further testing or medication." Luo Fei said that for this reason, the team building, training and guarantee of grassroots microscopic inspectors and qualified inspectors are very important.
Strengthen the grassroots prevention and control team
The sky is slightly bright, and the distant mountains and the near river are integrated. In the hazy mountain fog, the microscopic inspectors and parasitic disease prevention and control personnel from the township health centers in Yunyang County went to the Yunyang County Health Commission to participate in the 2024 endemic and parasitic disease training meeting held recently. The training will be organized by the Yunyang County Center for Disease Control and Prevention, and the training content includes parasitic disease prevention and control requirements, parasitic disease diagnosis and treatment techniques, parasite microscopic examination, etc.
At the end of the training, pictures of various parasite eggs under the microscope were played on the big screen, and the microscopic examiners who participated in the training answered questions on the spot to identify what kind of parasitic infection the picture showed.
"The test results have a 100% pass rate." Li Shiqi, a staff member of the Department of Endemic and Chronic Disease Prevention and Control of the Yunyang County Center for Disease Control and Prevention, who is responsible for on-site coordination and training, said that such training covers all relevant staff of township health centers in the county and is carried out regularly every year to better improve the professional capabilities of front-line prevention and control personnel, especially microscopic inspection capabilities.
Improving the monitoring system is an important part of the prevention and control of soil-transmitted nematode diseases. Luo Fei introduced that in order to ensure the stability of the prevention and control teams in various districts and counties, the Chongqing Municipal Center for Disease Control and Prevention has strengthened training for relevant personnel of the district and county disease control centers and medical institutions by holding training courses and parasitic disease prevention and control skills competitions.
Municipal disease control training districts and county-level disease control, district and county-level disease control training in various streets and townships, layer by layer training weaves a net, and the grassroots prevention and control team continues to expand. "There are many impurities in the specimens, and in the past, the microscopic examiners in many township health centers could not distinguish whether there were eggs or what kind of parasite eggs they were, so they could not judge whether they were infected or not. Nowadays, there are more people at the grassroots level who can microscopic examination, see and identify, and the accuracy is constantly improving. Luo Fei introduced that taking Yunyang County as an example, the county's qualified inspection staffing rate has increased from 40% in 2019 to 98% in 2023.
The reporter learned that from 2019 to 2023, the central government transferred local major infectious disease prevention and control projects to carry out prevention and control work in 23 counties (cities and districts) in 13 key provinces (autonomous regions and municipalities) where soil-borne foodborne parasitic diseases are prevalent, and Yunyang County participated in the project as a pilot county in Chongqing. In addition to the continuous increase in the staffing rate of qualified inspections, through the implementation of the five-year prevention and control project, compared with the baseline of 2019, the infection rate of soil-transmitted nematode disease in Yunyang County has decreased by more than 70%, the health education coverage rate has increased from 50% to 98%, and the awareness rate of prevention and control knowledge has increased from 70% to 98%.
"Relying on medical institutions at all levels, we carry out health education, patient investigation and treatment, and deworming of key groups throughout the county." Li Shiqi said that the county's soil-transmitted nematode disease prevention and control team is composed of public health physicians, clinicians, microscopic examiners and village doctors, and the number of personnel has increased from 137 in 2019 to 1,042 in 2023.
"What's more, the pilot in Yunyang County has accumulated a lot of practical experience, which can be further promoted and applied in other parts of Chongqing." Luo Fei said with a smile.
Focus on key populations
To a certain extent, the comprehensive control effect of soil-transmitted nematode disease is related to the health literacy, hygiene habits and socio-economic level of the population. "At present, soil-transmitted nematode disease mainly adopts a comprehensive prevention and control strategy of 'taking health science popularization as the guide and controlling the source of infection'." Luo Fei, who has been engaged in the prevention and control of parasitic diseases such as soil-transmitted nematode disease for nearly 18 years, shared.
Soil-transmitted nematode eggs or larvae enter the human body and become parasitic and multiply in the intestine. Soil-transmitted nematode disease can occur by eating unclean food with eggs, drinking unclean water, and having direct skin contact with larvae. "After humans are infected with soil-transmitted nematodes, the eggs are often excreted through feces, and these eggs enter the human body through fecal-contaminated soil, vegetables, fruits and other ways for various reasons, re-infect, and complete its life cycle cycle." Luo Fei introduced.
Chongqing has many mountains and fields, and many elderly people in rural areas do not like to wear rubber shoes or boots, and are accustomed to doing farm work directly with bare feet, which is easy to get infected. "The surveillance results show that at present, hookworm infection is still the main epidemic in Chongqing, and the main infected people are the elderly who work in the fields in rural areas." Luo Fei introduced that in order to control the source of infection, the five-year prevention and control project in Yunyang County summarized and refined the multi-level classification and deworming measures for key groups that combine active screening and deworming and health guidance and voluntary deworming.
Due to the large differences in urban and rural environmental sanitation, population awareness, and hygiene habits, and the relatively small number of infections of soil-transmitted nematode disease in urban areas, children aged 3~14 years old in urban areas are mainly publicized by schools. Li Shiqi introduced that the primary medical and health institutions in the jurisdiction of the city within the city area enter the campus at the beginning of the spring and autumn school every year to issue a proposal to each student, and adopt the principle of "informed, voluntary, and self-paying" to deworm, and a total of more than 60,000 proposals have been distributed.
"For key groups in rural areas, the strategy of first finding out and sorting and deworming for free is adopted." Li Shiqi introduced, rural areas 3 ~ 14 years old children in the school centralized deworming, over 50 years old agricultural people by the primary medical and health institutions checks, village doctors are responsible for specific one-to-one notification of deworming, each person per year free of charge 2 tablets of deworming drugs, deworming before signing the informed consent notice.
Every school season, health education classes related to soil-transmitted nematode disease are held in schools in Yunyang County, and many children in rural areas take what they have learned home and teach them to the elderly at home. Yunyang County also regularly carries out free health examinations for the elderly, and village doctors come to homes to carry out health education; Consultation points are set up in village clinics throughout the county, health education materials are provided, and health lectures are held...... Years of health knowledge have enabled the people of Yunyang County to gradually develop better hygiene habits.
"At the same time, we combined with the rural revitalization strategy to promote the improvement of the rural living environment, guide farmers to carry out indoor toilet renovation in rural areas of the city, strengthen the construction and maintenance of rural public toilets, and improve environmental sanitation." Luo Fei introduced.
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Text/photo: Duan Menglan, reporter of this newspaper, special reporter Ouyang Fangyi, Yu Fang
Editor: Liu Jiyue
Review: Gao Yankun, Pan Huahong, Yan Yan
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