The disaster impact of natural disasters

For different types of natural disasters, infectious disease control also has different characteristics. In this sense, disasters can be divided into sudden disasters, including floods, earthquakes, volcanic eruptions, tsunamis, typhoons and other natural disasters that have caused great damage in a short time; Progressive disasters, including drought and famine caused by rare insect disasters. Because the latter disaster did not have a sudden impact on the basic living conditions of human beings, the prevention and control of infectious diseases can be carried out more unorganized. (1) The drinking water supply system is damaged.

Most natural disasters may cause the destruction of drinking water supply system, which will be the first problem after the disaster, and often lead to the outbreak and epidemic of large-scale intestinal infectious diseases in the early stage after the disaster.

When a flood occurs, the original safe drinking water source is flooded, destroyed or blocked, and people are forced to use surface water as the main drinking water source. These waters are often polluted by human and animal excreta, human and animal carcasses and dirt in damaged buildings in the upper reaches, especially in low-lying waterlogged areas, where the victims have been besieged by floods for a long time and even caused the outbreak of water-borne diseases. During the floods in Bangladesh, a large number of people died.

During the earthquake, the destruction of buildings will also involve the water supply system, which will interrupt the normal water supply of residents and have a serious impact on urban residents. The remaining water sources are also easily polluted due to the destruction of pipelines. Tsunamis and windstorms may also cause this situation.

During the disaster, many drinking water sources dried up, leading to the concentration of drinking water sources. In some water-deficient areas prone to disasters, residents often need to go far away to get drinking water. Once these water sources are polluted, it will cause an outbreak of disease. For example, Batang, Sichuan, once had a very serious epidemic of bacillary dysentery due to drought.

In some low-lying saline-alkali areas, floods and droughts will also change the groundwater level, thus affecting the salt content and PH value of drinking water. When the PH value and salt content in water increase, it is beneficial to the reproduction of Vibrio cholerae. Therefore, in some cholera epidemic areas, cholera often recurs due to floods and droughts, and it can last for a long time.

(2) Food shortage

Although transporting food to the disaster area has become the first task of disaster relief, it is still difficult to completely avoid local food when a large-scale natural disaster involving a wide area occurs. Coupled with the destruction of basic living conditions, people are forced to store food under harsh conditions, which can easily lead to food mildew and corruption, food poisoning and the prevalence of food-borne intestinal infectious diseases.

Floods are often accompanied by rainy weather, when food is easy to get moldy. Recently, during the large-scale floods in several southern provinces of China, many incidents of mold poisoning occurred. When disasters occur in hot weather season, food is prone to spoilage. Because pickled food is easy to preserve, it often becomes the only non-staple food for residents when the supply of non-staple food is interrupted in large-scale disasters, which also provides conditions for halophilic bacteria poisoning.

Food shortage will also lead to a general decline in people's physique, thus making various diseases prone to occur and epidemic.

(3) Fuel shortage

In large-scale natural disasters, fuel shortage is also a common phenomenon, especially among victims trapped by floods.

Fuel shortage first forced the victims to drink raw water and eat cold food, which led to the occurrence and spread of intestinal pollution.

When it is difficult to restore fuel supply in a short time after a serious natural disaster, fuel shortage may lead to a decline in the personal hygiene level of residents. Especially in winter, people still live in a crowded state, which may lead to the breeding and spread of parasites on the body surface, which may lead to the resurgence of some infectious diseases that have been controlled, such as epidemic spot and typhoid fever.

(4) Water pollution

Floods often pollute water bodies and cause large-scale epidemics of some water-borne infectious diseases, such as schistosomiasis and leptospirosis. But the impact of flood on water pollution is twofold. In large-scale floods, especially in travel, due to the dilution of floods, the incidence of such diseases shows no obvious signs of rising. However, when the flood began to fall, many small bodies of water were left in the waterlogged area. If these small water bodies are polluted, it will easily lead to the outbreak and epidemic of such diseases.

(5) The living conditions are destroyed.

Floods, earthquakes, volcanic eruptions and tsunamis will all cause large-scale damage to living conditions. At first, people are forced to sleep outdoors, and then they may live in simple shacks for a long time, resulting in concentrated population and crowded living. During the Tangshan earthquake, in Tangshan, Tianjin and other big cities, simple shacks stretched for dozens of miles, and the longest lived for more than a year. Even after moving back to the original residence, due to the destruction of a large number of houses, some residential congestion will continue for a long time.

Sleeping outdoors makes people vulnerable to attack by blood-sucking arthropods. At this stage, the incidence of insect-borne infectious diseases may increase, such as malaria, Japanese encephalitis and epidemic hemorrhagic fever. The crowded population is conducive to the prevalence of some diseases spread through close contact between people, such as hepatitis and pinkeye. If this situation continues into winter, respiratory infectious diseases, such as influenza and epidemic cerebrospinal meningitis, will become a serious problem.

(6) Population migration

Natural disasters often cause large-scale population migration. During the Tangshan earthquake, the wounded were directly transported to Chengdu and Chongqing in the southwest hinterland of China. During the period of urban reconstruction, people evacuated in the form of relatives and friends almost spread all over China. Under today's economic conditions, going out to engage in labor activities has almost become the most important form of self-help activities for residents in disaster areas.

The large-scale migration of population first created conditions for the spread of some endemic diseases, and led to some diseases becoming epidemics, such as the Black Death in the Middle Ages. The latest plague epidemic in the history of China and Yunnan began with population movement.

Population mobility has caused two problems. First, when the population in the disaster area flows out, it may spread the endemic diseases in the disaster area to the disaster-stricken areas. More importantly, when the disaster area begins to rebuild and the population returns home one after another, endemic diseases and infectious diseases will be brought back to the disaster area. If the disaster area has the conditions for epidemic diseases, it may create new epidemic areas.

The second major problem of population mobility is that it interferes with the immune status of some people who mainly rely on immunity to control diseases, resulting in local non-immune people, thus creating conditions for the prevalence of these diseases.

In China, planned immunization has been widely carried out, and great achievements have been made in controlling polio and measles. The incidence of typhoid fever, tuberculosis, hepatitis A and hepatitis B began to decline. Due to the interference of disasters, it is difficult to carry out planned immunization work normally, and some children miss vaccination due to abortion, which may increase the incidence of such diseases.

Some diseases that often occur among children and young people, as well as diseases in the natural immune state of the population, play an important role in the epidemic. No matter the outflow of people from the disaster area or the return of people during the reconstruction of the disaster area, some non-immune people will come into contact with the low-level natural epidemic population, which will lead to an increase in the incidence of these diseases. Many infectious diseases not only spread from person to person, but also have other biological hosts besides people. Some diseases must be transmitted through biological media. Disaster conditions have destroyed the old ecological balance among human beings, host animals, biological media and disease pathogens, and will establish a new ecological balance on a new basis. So the impact of disasters on these diseases will be more lasting.

(1) flies

Flies are important vectors of intestinal infectious diseases, and their breeding and reproduction are mainly determined by the unsanitary living environment of human beings. Major natural disasters will always cause great damage to the sanitary conditions of human living environment, and the breeding of flies is almost inevitable.

After the earthquake, the house collapsed. Buried under the ruins are the bodies of dead people and animals, as well as a lot of things and other organic substances. Under the climatic conditions of temperature, these organic components will rot rapidly, which provides conditions for flies to reproduce easily. Therefore, earthquake damage as large as Tangshan earthquake often causes a surprising number of adult flies in a very short time, posing a serious threat to the residents in the disaster area.

After the flood recedes, drowned animal carcasses and all kinds of organic garbage will be largely silent in the ruins of the old village, and if they are not removed in time, a large number of flies will also breed.

Even in the case of drought, due to lack of water, there will be some unsanitary conditions, which is conducive to the breeding of flies. Therefore, in the early stage of post-disaster reconstruction, eliminating flies will become an important task of infectious disease control.

(2) mosquitoes

Among the blood-sucking arthropods that spread diseases, mosquitoes are the most important and closely related to disasters. Under the common disaster conditions in China, malaria and Japanese encephalitis are the most serious threats to the residents in the disaster areas.

Mosquitoes need a small and still water body to breed. Therefore, in flood water, the increase of mosquito density is often not obvious during flood discharge. However, after the water recedes, a large number of small waterlogged areas often appear in the low-lying areas of waterlogged areas, which are overgrown with weeds and become the best breeding ground for mosquitoes. At this time, if there is a source of infection, the incidence in this area will increase rapidly.

Drought will cut off some rivers and dry up lakes, and the small puddles left in these rivers and lakes will also become good breeding grounds for mosquitoes.

In earthquakes, wind disasters and other disasters that cause a lot of damage to buildings, water storage buildings and pipelines may be damaged at the same time. The overflow of tap water, especially domestic sewage stranded on the ground, will also become an environment for mosquitoes to multiply.

Disasters will not only increase the density of mosquitoes, but also increase the chances of mosquitoes attacking humans. Residents trapped by floods and forced to sleep outdoors due to the destruction of houses often lack effective means to resist mosquito invasion, which is also an important reason for the increase in the incidence of mosquito-borne diseases.

(3) Other blood-sucking arthropods

Under disaster conditions, the chances of blood-sucking arthropods attacking humans are mainly increased, and mosquitoes sometimes mechanically spread some rare infectious diseases, such as anthrax. People who sleep in places rich in weeds and humus are vulnerable to chigger mites and gamasid mites. In areas with tsutsugamushi disease and epidemic hemorrhagic fever, this threat to human beings has greatly increased. Disasters in forest areas, such as forest fires, will increase the chances of tick bites and may lead to a series of diseases such as forest encephalitis, Lyme disease and spotted fever.

(4) Parasites

In China, the distribution of schistosomiasis is mostly in some flood-prone areas, while the distribution of snails is greatly affected by floods.

In normal times, the distribution of Oncomelania hupensis constantly changes with the scouring of water and the formation of shoals. Under flood conditions, it is possible to take snails away from their original breeding grounds and settle down in a new and suitable environment. Therefore, floods often significantly expand the distribution area of schistosomiasis.

(5) Livestock

Domestic animals are important hosts of many infectious diseases. For example, pigs and dogs are hosts of leptospirosis, pigs and horses are hosts of Japanese encephalitis, and cattle are hosts of schistosomiasis. When a flood disaster occurs, a large number of victims and livestock are often trapped in their narrow areas by floods. The natural return to the sea has caused great damage to houses, and it will also lead to an unusually close relationship between people and livestock. This environment will make it easy for people and animals to spread infectious diseases.

(6) Domestic and wild rodents

Domestic and wild rodents are the most important disease hosts, and their distribution and density are obviously affected by natural disasters.

Most rodents related to diseases live in underground caves, and their swimming ability is not very strong. Therefore, when a large-scale flood occurs, the number of rodents will decrease. However, some rodents may use floating objects to escape and concentrate in the higher places where the victims live, thus forming an unusually high density in some areas. In this case, due to the close contact between humans and rodents, it is possible to cause the epidemic of diseases.

Because of the strong reproductive ability of rodents, they usually leave abundant food for rodents in villages and farmland damaged by floods. Therefore, after the flood recedes, the density of rodents may rise rapidly, and a very high population density will appear for a period of time thereafter, thus promoting the epidemic of infectious diseases and endangering human beings.

Drought may dry up some lakes and swamps and turn them into overgrown lowlands. This area provides a superior living environment for wild rodents, which makes their number increase sharply. It is reported that this situation leads to epidemic hemorrhagic fever in the population.

Natural disasters such as earthquakes have caused a large number of houses to be destroyed, and some houses that were not easily invaded by rodents have been destroyed. A large amount of food left in the ruins has enabled domestic rodents to obtain a large number of breeding conditions. When post-disaster reconstruction begins and residents move back to their original houses one after another, rodent infestation may become a major problem, and the incidence of diseases transmitted by rodents may also rise. Due to the influence of natural disasters on the pathogenesis of infectious diseases, after natural disasters, the incidence of infectious diseases may show stage characteristics.

When sudden natural disasters occur, the sources of drinking water and food are destroyed first, so intestinal infectious diseases will be the main threat in the later period. In particular, water pollution and food poisoning tend to accumulate a large number of people, which should be the focus of early disease control after disasters.

The destruction of houses makes a large number of people live in the open air and vulnerable to the invasion of blood-sucking arthropods. But due to the invasion of arthropods. However, because the number of arthropods and infectious sources need to be accumulated, the occurrence of infectious diseases is usually a little late, which may be a gradual process.

Excessive concentration of population has increased the incidence of infectious diseases through close contact. If the scale of the disaster is large, the population in the disaster area needs to live in isolation for a long time, and when the cold season comes, the incidence of respiratory infectious diseases will also increase.

Population migration may cause two peaks. The first peak is caused by the outflow of population, but because the patients are scattered in a large range of non-disaster areas, this peak is often difficult to detect and cannot be paid attention to accordingly. When the reconstruction of the disaster area begins and the displaced people return home, there will be a second peak of incidence, which is often manifested as the incidence rate among children.

Finally, the post-disaster is actually a process of ecological balance reconstruction, which may last for two or three years or even longer. During this period, infectious diseases suffered by humans and animals and infectious diseases spread through biological media may show different characteristics from normal time, and may have higher incidence. In view of the impact of the above-mentioned natural disasters on the incidence of infectious diseases, the prevention and control of infectious diseases after natural disasters should have different characteristics from usual, and the organization and leadership of prevention and control should be related government departments. According to the characteristics of infectious diseases in disaster period, the control of infectious diseases can be divided into four periods.

(1) Pre-disaster period

China is a big country, and some areas are prone to natural disasters. Therefore, preparations should be made before disasters occur, including the prevention and control of infectious diseases.

1. Accumulation of basic data. In order to formulate scientific prevention and control countermeasures in times of disasters, attention should be paid to the accumulation of basic data in peacetime, including population data, health data, incidence data of infectious diseases, distribution data of major endemic diseases and distribution data of major animal hosts and vectors.

2, formulate infectious disease control plan. In some disaster-prone areas, such as earthquake-active areas, low-lying areas in the lower reaches of major rivers and flood diversion areas, there should be emergency plans when disasters occur, including infectious disease control plans. The plan should determine the focus of disease prevention in different periods according to the specific situation of each disaster-prone area. The deployment of mobile teams that can be sent to disaster areas, as well as the storage location and deployment plan of urgently needed disease prevention materials and equipment, should also be considered in prevention.

Due to the sudden occurrence of natural disasters, it is impossible to make a plan for every area that may be affected. In order to facilitate demonstration, we should make a more detailed plan according to some typical areas.

3, mobile epidemic prevention team to prepare. Due to the impact of natural disasters, disaster areas often do not have enough health and epidemic prevention and medical strength to deal with emergencies that have occurred. In the face of sudden disasters, the existing epidemic prevention teams are often in a state of temporary confusion and paralysis. Therefore, when a major natural disaster occurs, it is necessary to send a mobile epidemic prevention team into the disaster area to support disease control.

4. For some disaster-prone areas, the personnel of these mobile teams should be trained regularly to let them know about the health and diseases in the main mobile direction and the problems they may encounter after entering the disaster area. When the personnel changes, the personnel of these mobile teams should also be supplemented and adjusted in time to cope with emergencies at any time.

(2) Disaster shock period

When a large-scale natural disaster strikes suddenly, it is almost impossible to carry out effective disease prevention and control. However, during this period, medical teams sent to disaster areas for the purpose of emergency rescue should be equipped with enough drinking water disinfection places and drugs to prevent and treat intestinal infectious diseases, and pay attention to the signs of large-scale infectious diseases and carry out appropriate treatment to control the initial outbreak of diseases.

(3) Post-disaster period

When residents in disaster areas are out of danger and temporarily live in safe areas, disease prevention and control should be carried out systematically:

1, rebuild the surveillance system of mass diseases.

Due to the impact of major natural disasters, the disaster relief work is heavy and the personnel flow frequently, the disease monitoring and reporting system established at ordinary times is often paralyzed in the early days after the disaster. Therefore, the primary task of the health management department and the mobile epidemic prevention team should be to rectify it and re-establish the epidemic reporting system according to the situation of the victims, so as to find the epidemic situation in time and deal with it correctly. The contents of monitoring should include not only the legally reported infectious diseases, but also the temporary residence and mobility of the population, the occurrence of major diseases, and the number of rodents and vectors in and around the residents' temporary residence.

2. Rebuild the safe drinking water system.

Because the destruction of water diversion system poses the most serious threat to people, all possible measures should be taken to restore and ensure the safe drinking water supply first.

3. Vigorously carry out health campaigns.

Improving the sanitary conditions of temporary shelters after disasters is an important link to reduce the occurrence of diseases. Therefore, when residents are basically out of danger and arrive at a safe place, they should be organized to continuously improve the sanitary conditions at home, remove garbage and dirt, spray pesticides regularly to reduce the density of mosquitoes and flies, and carry out rodent control when necessary.

When reconstruction begins after the disaster, the sanitary conditions of the original residence should be improved before moving back to the original residence.

4. Prevent the invasion of blood-sucking insects.

It is impossible to reduce the density of blood-sucking insects to a safe level when residents are forced to sleep outdoors. Therefore, the main means to prevent insect-borne infectious diseases is to prevent insect bites. You can use all possible methods to protect people from the bites of blood-sucking insects such as mosquitoes. For example, use plants with natural insect repellent function to kill and drive mosquitoes, and try to transfer mosquito nets, mosquito repellent and other materials to the disaster area.

5, timely find and deal with the source of infection.

Under the condition of major natural disasters, it is often difficult to improve the phenomenon of crowded population and mixed living of people and animals in a short time. Therefore, finding patients and timely and correct isolation treatment are the basic means to reduce infectious diseases.

Some diseases, such as hepatitis and malaria, are the only source of infection. Therefore, residents in disaster areas should pay special attention to finding such patients in time and transferring them to medical units with isolation conditions for treatment.

In addition, many diseases can occur not only in humans, but also in animals. Therefore, it is necessary to pay attention to the inspection of domestic animals such as pigs, cattle, horses and dogs in the disaster areas, find the infection of leptospira, schistosomiasis and Japanese encephalitis in time, and deal with the animals that become the source of infection in time.

6, out of the crowd for diagnosis.

After the fire, a large number of people will leave the disaster area in the form of engaging in labor activities or visiting relatives and friends. Therefore, in the surrounding areas of the disaster area, especially in large and medium-sized cities, people from the disaster area should be specially inspected to find the epidemic signs of infectious diseases in time. In some endemic areas, these floating population should also be immunized to avoid the outbreak of some endemic infectious diseases.

(4) after-effect period

When the affected people moved back to their original places of residence and started post-disaster reconstruction, the prevention and control of post-disaster infectious diseases entered the stage of aiming at post-disaster effects.

1. Carry out physical examination and immunization for the returned population.

At this stage, the population flowing out of the disaster area began to return home one after another, and the focus of infectious disease prevention and control work should be shifted to prevent the returning population from having a second peak.

People who go out to engage in labor services may enter some epidemic areas, get infected there, and may bring the host and media of the disease back to their hometown. Therefore, inspection should be strengthened among returnees to find out which endemic areas (such as plague, brucellosis, schistosomiasis, etc.). They have arrived and checked these possible situations. If patients are found, they should be treated immediately.

Babies born in other places often lack immunity to some common diseases in their hometown, so it is necessary to strengthen the examination of infants and young children in order to find and treat their diseases in time.

Because it is difficult for floating population to carry out normal planned immunization work, there is often an immunization gap between these populations. Therefore, timely supplementary immunization is an important measure to prevent the incidence from rising.

2. Reconstruction of disaster areas and re-investigation of diseases.

Natural disasters can often cause the expansion of animal infectious diseases such as schistosomiasis, leptospirosis and epidemic hemorrhagic fever, and lead to changes in the distribution and epidemic intensity of animal diseases. Therefore, in the post-disaster reconstruction period, we should re-investigate the distribution of these diseases and take corresponding preventive measures to prevent them from breaking out during the reconstruction process.

For families and individuals in disaster areas, we should pay attention to the following points:

(1) Pay attention to the cleanliness of drinking water. If possible, listen to the guidance of disaster relief personnel and strictly disinfect with drugs. If there are no conditions, try to boil the water before drinking. Never quote polluted water just because of trouble.

(2) Cooperate with disaster relief personnel to kill flies, mosquitoes and rats and do everything possible to prevent mosquito bites.

(3) found abnormal situation, such as someone around sick, have a fever, suffering from skin diseases, etc. , should immediately report to the disaster relief personnel or relevant departments.

(4) Try to avoid multiple people living in the same room, and try to avoid sleeping with animals, even their own poultry and livestock.

⑤ Unless necessary, don't move at will without the organization and guidance of relevant personnel. People who go out should not rush into the disaster area because they care about the safety of their relatives and friends.

⑥ When the supply of tap water and other water sources is interrupted after the disaster and residents need to drink groundwater, fire water and other water, attention should be paid to ensuring the safety of drinking water. If the tap water supply is interrupted after the disaster, bottled water should be given priority, or boiled in a designated place for drinking.