Mosquitoes, flies, rats and cockroaches often haunt parklands, residential courtyards, farmers' markets, garbage dumps and other places. The monitoring cycle of different vector organisms depends on their characteristics, flies and mosquitoes are more frequent in the summer every year, starting from April and May, once a month, while rats and cockroaches are active almost all year round, so normal monitoring is required. These trivial and important tasks, known as vector biological surveillance, are an important systemic foundation for disease prevention and control.
April this year is the 33rd patriotic health month, the reporter followed the staff of the Beijing Miyun District Center for Disease Control and Prevention into the farmers' market and other key monitoring sites to record this group of people who deal with the "four harms".
01 "Commuting" with rats and flies
"In addition to the difference in active months, the active time of the vector organism is also different during the day. Flies are monitored at 9 a.m., while mice and cockroaches are monitored by night and collected early the next morning. Yang Yusong, head of the Disease Control Department of the Center for Disease Control and Prevention of Miyun District, Beijing, and Zhang Jisong, deputy chief of the section, have already adjusted their working hours to the same channel as the active time of vector organisms, "going to work" together, and "going off work" together. "Working hours should be in line with their habits. These organisms have their own laws of dissipation, which are related to factors such as environmental temperature and precipitation. ”
↑ At 9:00 a.m., the crew loaded the flycatcher into the car and prepared to leave.
Huayuan Market is the largest wholesale market in Miyun District, selling grain and oil, aquatic products, vegetables and fruits, etc., is the source of food and beverage canteen procurement, food safety issues are of paramount importance, and is an important point for vector biological monitoring.
At 9:00 a.m., in the huayuan market dry vegetables and spices tobacco and wine hall, the taste of pepper and pepper noodles mixed together came to the nose. "Hello customers, for your safety, please consciously wear a mask." Loudspeakers looped the slogan of epidemic prevention. Because it was past the purchase time, the vendors were counting and sorting out the goods, and only a few customers stopped in front of the store to bargain.
↑In a shop full of goods, the staff sprinkles cockroach bait on sticky cockroach boards,
And place in a place where there is food scraps and protected from light.
"Cockroaches prefer warm, humid, food debris environments, and are protected from light." Zhang Jisong shuttled between the goods filled in each storefront, where it was dark and dirty, he drilled wherever he went, holding a flashlight to carefully search for cockroach corpses and remnants of egg shells. In a place where flour was spilled, Zhang Jisong sprinkled cockroach bait on a sticky cockroach board and placed it there. "Pay attention to cleaning, prepare some sticky cockroach plates for you, and just put them in a place where food is often left as I just did." Once found, use boiling water or burn off the sticky cockroach board, if you throw it away, cockroach eggs have a suitable environment and will breed. Zhang Jisong did not forget to guide the merchants after finishing the sticky cockroach board.
↑ In the kitchen of a resident's home, the staff placed sticky cockroach boards where cockroaches might appear.
At a fish stall in the aquatic area of Huayuan Market, carp, crucian carp, etc. spit bubbles in the tank. Fresh crayfish crawl around in large red pots. The shopkeeper was scraping the scales with his tools, and soon the garbage bin was piled up with garbage. "The mercerized green fly, which is what we call the green bean fly, loves to fly here."
Zhang Jisong took out the pre-prepared bait for trapping flies, poured it into a vessel, and placed it under the flycatcher cage. Zhang Jisong told reporters that the bait is now a mixture of 50 grams of brown sugar, 50 grams of aged vinegar and 50 ml of water, replacing the previous stinky tofu soup. "Stinky tofu is very tempting and can attract a large number of flies, but the specificity is strong, only attracting rotten flies, and the number of other types of flies is less, which will affect the population ratio of flies." Sweet and sour water, although caught in small quantities, is relatively average. Both approaches have pros and cons, but from the long-term monitoring curve, the overall fading trend is roughly the same. ”
After a while, Zhang Jisong's clothes printed with "Chinese health" could be described as "full of color and fragrance". Dealing with mosquitoes, flies, rats and cockroaches for many years, you need to endure all kinds of pungent strange smells, in the face of such a drudgery, Yang Yusong worked for 20 years, Zhang Jisong dried for 10 years. "Are you tired of looking at these bugs every day?" In the face of reporters' questions, Yang Yusong said, "What is this annoying, the work is important." ”
At three or four o'clock in the afternoon, it was the time for Zhang Jisong to collect the fly catcher cage, and the reporter followed him to various points to collect the net. "I only caught one fly!" Seeing the reporter's regret and loss, Zhang Jisong said with a smile, "Catching flies is a probabilistic event, and sometimes flies just don't fly into the cage, and it is possible to catch them with a certain density." Moreover, April is the time when the fly has just emerged, and its fading trend is a parabolic trend, with a trough of density in early April and the end of October, and a peak in July and August. ”
02 Small majors throughout the university asked
What is the use of monitoring such a humble mosquito fly rat cockroach?
Wang Huayong, deputy director of the Beijing Miyun District Center for Disease Control and Prevention, said that although there are not many vector biological infectious diseases in Beijing, they are mainly Japanese encephalitis and hemorrhagic fever. However, from a preventive point of view, these infectious diseases will pose a serious threat to the health of residents, and the harassment of mosquitoes, flies, cockroaches and rats has attracted widespread attention. Routine vector biological surveillance, if problems are identified, require research and control measures. For example, if the monitoring finds that the data of mosquitoes and flies and cockroaches is abnormal, it is necessary to study what kind of methods to use, what kind of drugs to use to kill, and then some tests and product tests will be done. "On the one hand, it is to carry out prevention and control work to reduce the occurrence of diseases; on the other hand, through the average accumulated over several years, it provides the government with adjusted disease prevention strategies." For example, in the summer, the density of these vector organisms increases, prompting a focus on food safety and intestinal disease prevention. ”
"You see the fly stop at the food and fly away leaving a small dot, which is actually what the fly spits out." Yang Yusong said that mosquitoes, flies and cockroaches, which are actually porters of bacteria, are mechanically transmitted, and in most cases can cause intestinal diseases. For example, mosquitoes by sucking the blood of the bacterium, flying to the next object to spit out and then re-suck blood, at this time the formation of bacterial plugs, in fact, already has a high concentration of bacteria. Different kinds of organisms, the radius of activity, the activity environment is different. For example, around the fish stalls, there are many mercerized green flies, there are more houseflies in residents' homes, and rot flies in toilets. "Only by firmly grasping their living habits and studying them thoroughly can we find more focused prevention and control measures."
↑According to years of experience, the staff put mouse clips on the side of the dark and damp wall.
It is not an easy task to master the skills of catching mosquitoes, flies, rats and cockroaches. Wang Huayong gave an example of once taking a newly hired colleague to the scene to catch rats, and the new colleague put the mouse clip on the open ground. "It certainly doesn't catch rats." The mouse has a bad look, relies on its beard to perceive the direction, and walks against the wall. This is both a science and an accumulation of experience. "Wang Huayong said that the new colleague put the mouse clip at the root of the wall according to what he said in the next action, and was stopped by Wang Huayong." There are many spider webs at the root of this wall, indicating that there have been no animals passing by for at least a few days, and it will not work when released. Ineffective under the clip, on the one hand, affects the statistics, on the other hand, wastes manpower and material resources. ”
↑ Inside the warehouse where the feed is stored, the staff holds mouse clips and prepares to lay traps.
"It looks like a small major, but the actual knowledge is great." In Zhang Jisong's notepad, the content is densely written, prompting the gap between the characteristics of some bugs in the book and reality, and remembering which expert to consult if you encounter professional problems. "There is still a gap between the knowledge learned in the books and the actual operation, and we must 'learn to do, do to learn'."
03 Someone has to do the work
In addition to identifying species and summarizing quantities, some vector organisms have been made into specimens to retain information. In the specimen room on the first floor of the CdC in Miyun District, there are several large cabinets of specimen boxes displaying specimens of mosquitoes, flies, rats and cockroaches from the 1980s to the present. Zhang Jisong carefully took out one of the specimen boxes for the reporter to see, that is, the fly specimen stretched its wings. Each row belongs to the same category, and under each specimen is a label that says who collected it, where and when it was collected.
"This is our 'treasure' handed down from generation to generation, condensing the evolution of local vector organisms in Miyun." Wang Huayong said that the main role of specimens is to retain data, and also provide information for scientific research. "Pale Culex, Hemp fly, the morphology of different periods is slightly different, which is related to the living environment and ecological changes, the reasons for the change are worth studying and exploring."
"This five-browed chipmunk is a precious specimen because it's clever and difficult to catch." "You see this Bruce's vole, which we borrowed from other places when we visited and studied, is not a native rat species." "In the 1980s, we also caught flies that looked like bees." Although the specimen is sealed in a box, the story behind it is still talked about by the disease controller.
Watching these rats all lie there in the same posture, it is impossible to reflect their real posture in the wild, and how to show their original appearance has become Wang Huayong's heart. "Haddock rats can transmit haemorrhagic fever virus, and if you want to know the population proportion in this area, if you don't even know what it looks like, what is the catch?" Once, when Wang Huayong went to a foreign country to visit and study, he had the idea of making dynamic specimens. Dynamic specimens are to restore the form of animals in the wild, some standing, some squatting, different forms, giving people a more intuitive and vivid feeling. But the work was stranded, and the reason was still human problems. Yang Yusong and Zhang Jisong's department is responsible for vector monitoring and disinfection, in addition to the monitoring of medical institutions, schools and other places, and the new technology needs to go out to learn, in their words, "really lack of skills." Zhang Jisong calls himself a "newcomer", and after him, the center has no newcomers who have inherited the craft of making specimens.
"Over the years, although some people have left because of the hard work of disease control, there are also new forces to supplement them. It is believed that with the continuous deepening of reform, the disease control system will be more perfect. Wang Huayong looked out the window and said.
Text: Health Daily reporter Yang Jinwei special reporter Zhang Linlin
Photo: Zhang Dan, a reporter from The Health Newspaper
Editor: Zhang Fangfei
Review: Bingnan Xu