Chapter 5 Post-disaster epidemic analysis and prevention-5

The large number of deaths caused by disasters often aggravates people's concerns about disease outbreaks. However, in fact, there is currently no evidence that a large number of dead bodies will lead to post-disaster infectious disease outbreaks.When the death is caused by the natural disaster itself, there is no risk of an infectious disease outbreak for the survivors.The risk of dead bodies causing infectious disease outbreaks is only present in certain conditions requiring special precautions, such as cholera or hemorrhagic fevers. Please refer to Appendix 1 for the handling principles of the dead body.

Regardless of the facts, the likelihood of post-disaster outbreaks is often exaggerated by health authorities and the media.Despite scientists' attempts to dispel these unfounded myths, 'the threat of an imminent epidemic' has always been a recurring theme in media coverage of disaster zones. The risk of post-disaster transmission of infectious diseases is mainly related to the number and characteristics of population migration, including: whether there is drinking water and available toilets nearby, the nutritional status of the displaced population, the proportion of the population that has been immunized against infectious diseases such as measles, And whether there are health care services and so on.Disease outbreaks are at lower risk in people exposed to natural disasters than in people exposed to conflict, where two-thirds of deaths may be caused by disease.Malnutrition, which increases the risk of dying from disease, is more prevalent in conflict, especially as populations migrate as a result of protracted conflict.

Outbreaks of disease following floods are more well documented than conditions following earthquakes, volcanic eruptions, and tsunamis.In general, however, there are few outbreaks of disease following natural disasters (of any type) that do not cause population migration. Historically, large-scale population migrations due to natural disasters have been uncommon, and it is likely that human history This is one of the reasons why large-scale disease outbreaks in the world are not frequent, which also explains why the risk of disease outbreaks after different types of disasters varies. In order to effectively assist the affected population, we need to accurately assess the risk of the epidemic.Based on the risk assessment of the epidemic, we can allocate disaster relief funds in a prioritized and sequential manner.

A systematic and comprehensive assessment of the epidemic risk needs to confirm the following points: ? Common endemic and epidemic diseases in the affected areas; ? The living conditions of the people in the disaster area.Including population size, size, place of residence, and density of settlement; ? The supply of clean water and whether the sanitation facilities are adequate; ? The basic nutritional status and vaccination rate of the population in the disaster area; • Health care and case management status. The following groups of communicable diseases are associated with populations displaced by natural disasters.The following diseases should be treated with caution when conducting post-disaster risk assessments.

? Water-related infectious diseases ? Diseases associated with crowd density ? Vector-borne diseases ? Other diseases associated with natural disasters ? Illness due to catastrophic supply disruptions A safe and clean water source may be destroyed by a natural disaster.Diarrheal disease outbreaks can occur after drinking water is contaminated, and have also been reported following floods and associated displacement.In an outbreak following the Bangladesh floods in 2004, more than 17,000 cases had diarrhea, and Vibrio cholerae (Ogawa and Inaba serotypes) and toxigenic Escherichia coli were detected.

A major outbreak of cholera in West Bengal (serotype Ogawa, more than 16,000 cases) in 1998 was also linked to the previous flood. Floods in Mozambique from January to March 2000 also contributed to an increase in diarrheal cases. In a large-scale study in Indonesia in 1992-1993, flooding was identified as an important risk factor for diarrheal epidemics caused by Salmonella paratyphi A. In another evaluation study on the risk factors of Cryptosporidium parvum infection in Indonesia from 2001 to 2003, compared with the control group, the probability of the patients in the case being exposed to floods was more than 4 times.

The risk of diarrheal outbreaks following natural disasters is higher in developing countries than in developed countries.In the Indonesian province of Aceh, a rapid health assessment in the town of Jalang two weeks after the December 2004 tsunami found that 100 percent of the survivors drank from unprotected wells, compared with 85 percent in the previous fortnight. % of residents reported diarrhea. In Muzaffarabad, Pakistan, severe watery diarrhea broke out among 1,800 people living in an unplanned and poorly equipped camp following a 2005 earthquake.The outbreak has a total of more than 750 cases, most of them adults.After providing adequate drinking water and sanitation facilities, the epidemic was brought under control.

In the United States, diarrheal disease was also documented after hurricanes Allison and Katrina.Norovirus, salmonella, and the toxin-producing cholerae bacterium have been found in people evacuated from Hurricane Katrina. Hepatitis A (A) and E (Hepatitis E), mainly transmitted by the fecal-oral route, are also associated with a lack of safe water and sanitation. Hepatitis A is endemic in most developing countries, and most children are immune because they were infected at an early age.As a result, the chances of a large hepatitis A outbreak are usually lower.In areas with hepatitis E cases, outbreaks of the disease usually follow heavy rains and floods; the disease is usually mild and localized, but the mortality rate in pregnant women can be as high as 25 percent .After the 2005 Pakistan earthquake, sporadic cases of hepatitis E occurred in areas lacking safe water.Among displaced refugees, more than 1200 cases of acute jaundice were identified, many of which were identified as hepatitis E.Aceh, Indonesia, also had clusters of hepatitis A and E cases after the December 2004 tsunami.

Leptospirosis is an endemic bacterial disease transmitted by animals and spread by direct contact with contaminated water.The urine of rodents (rats) contains a large number of Leptospirosis bacteria, and the routes of transmission include contact of skin and mucous membranes with water, contact with moist soil, fruits and vegetables, or contact with mud contaminated by this urine.The dispersal of rodents after the floods, and the close contact between humans and rodents as they shared highlands, exacerbated the spread of the disease. Outbreaks of leptospirosis followed typhoon Nali in Taiwan, China in 2001, floods in Mumbai, India, 2000, floods in Argentina in 1998, and the Krasnodar disaster in the Soviet Union in 1997. Regional analysis following the 1996 flood-associated leptospirosis outbreak in Brazil showed that leptospirosis incidence more than tripled in flooded areas of Rio de Janeiro.

Post-disaster evacuations often lead to dense crowds and contribute to the spread of communicable diseases.Whether diseases such as measles will appear after a disaster, and the risk of disease transmission, depends on the basic situation of the vaccination rate among the infected population, especially the vaccination rate among children under 15 years old.Crowded living conditions encourage the spread of diseases such as measles, requiring higher vaccination rates to avoid outbreaks. After the eruption of Mount Pinatubo in the Philippines in 1991, measles broke out among the evacuees, infecting 18,000 people. After Aceh was hit by the hurricane, 35 small-scale clusters of measles occurred in the Aceh Utara area. Despite the continuous promotion and promotion of vaccination, individual cases or clusters still appeared.In Pakistan, sporadic and clustered measles cases (more than 400 patients within 6 months after the earthquake) also occurred after the 2005 South Asian earthquake.

Prokaryotic meningitis spreads from person to person, especially in crowded settings.Meningitis cases and deaths have been reported among displaced populations in Aceh and Pakistan.When an epidemic occurs in the above two places, timely antibacterial and epidemic prevention measures should be able to prevent the spread of meningitis.There have been no recent reports of large-scale outbreaks among affected populations, but outbreaks have been well documented among populations displaced by regional conflict. Acute respiratory infection (ARI) is an important cause of illness or death among disaster victims, especially for children under 5 years old.Lack of access to medical care and antimicrobials increases mortality due to acute respiratory infections (ARI).Risk factors for disaster victims include crowding, cooking indoors over open fires, and malnutrition.In 1998, 30 days after Hurricane Mitch hit Nicaragua, the number of patients with acute respiratory infection (ARI) increased fourfold; ) and the number of deaths from it is also the highest. Translator's Note: Disease vector, a medical term, refers to the intermediary factor that connects pathogens (bacteria, viruses, protozoa, worms) and infected objects (mostly vertebrates) in the process of disease transmission.Vectors are mostly insects (Diptera, fleas, etc.) but may also be aquatic molluscs. Natural hazards, especially meteorological hazards such as tornadoes, hurricanes and floods, can affect vector breeding sites and the spread of vector-borne diseases.On the one hand, the initial flood washes away existing mosquito breeding sites, but on the other hand, stagnant water caused by heavy rains or overflowing rivers can also create new breeding sites. Such conditions lead (usually after a delay of several weeks) to an increase in vector populations (such as mosquitoes, etc.) and to the spread of the disease.Of course, this also depends on the local media species and their preferred habitat conditions.Concentrations of infected or susceptible populations, weakened public health infrastructure, and disruption of existing disease control systems are all factors that contribute to the spread of vector-borne diseases. The spread of malaria after floods is a well-known phenomenon. In 1991, an earthquake in the Atlantic region of Costa Rica led to environmental changes in mosquito breeding grounds, followed by a sharp rise in malaria cases.In addition, in the dry coastal areas of northern Peru, malaria epidemics are also linked to the El Niño-Southern Oscillation. Air pressure anomalies.)” caused by periodic floods. Dengue transmission is also influenced by climatic conditions, including rainfall and humidity, and often exhibits strong seasonality.However, its spread is not directly related to the flood.The cases of outbreaks in previous floods may have coincided with the high-risk period of disease transmission.In addition, the destruction of basic water supply systems and garbage disposal facilities in natural disasters has also brought more breeding grounds for vectors (mostly water containers), thereby aggravating the epidemic. Outbreak risk may also be affected by other complicating factors, such as changes in human behavior (increased exposure to mosquito bites when outside overnight; population shifts from non-dengue endemic to dengue areas; disease control activities overpopulation), or environmental changes that affect mosquito breeding (such as landslides, deforestation, building dams or water diversions, etc.). Other diseases associated with natural disasters The transmission route of tetanus is not from person to person, but is caused by the toxic substances released by anaerobic tetanus bacilli.In populations with low tetanus vaccination rates, wound infections predispose to tetanus-related illness and death.Two and a half weeks after the Indian Ocean tsunami, there were 106 cases of tetanus in Aceh, Indonesia, including 20 deaths. Cases of tetanus were also reported after the 2005 Pakistan earthquake. Following the Southern California earthquake in January 1994, a rare outbreak of coccidiomycosis (commonly known as valley fever) erupted.Infection with this disease does not spread from person to person, but is caused by the fungus Fungus coccidioides, which is found in soil in some semi-arid regions of the northern and southern United States.Landslides followed the earthquake, which increased the amount of dust floating in the air, causing disease outbreaks. Power outages due to disasters can disrupt drinking water and supplies, increasing the chances of disease transmission through drinking water.Power outages will also affect the normal work of some medical equipment, including vaccine storage and cryogenic transportation. A massive power outage in New York City in 2003 caused a massive increase in local diarrheal illnesses.The accident caused about nine million local residents to lose power supply, and the time ranged from several hours to two days.Large-scale transmission of diarrheal disease was detected by unconventional means of surveillance at the time.A study on disease control found that power outages shut down refrigerators and that diarrhea was caused by people continuing to eat unkept meat and seafood in refrigerators.