In the wake of natural and human-made disasters, displaced populations, often living in overcrowded shelters with disrupted access to clean drinking water, proper sanitation systems, and adequate medical services, face conditions conducive to the rapid spread of infectious diseases. In some instances, morbidity and mortality from infectious disease in disaster zones may be even greater than that caused by the direct impact of the disaster itself. Recognizing, controlling, and treating infectious disease outbreaks in these settings has challenged the ingenuity of many health care workers since the beginning of human civilization and will continue to do so in the future. The purpose of this chapter is to provide a framework that physicians involved in disaster relief may use to aid the prevention, identification, and control of infectious disease in disaster zones.
The World Health Organization (WHO) defines a disaster as a catastrophic situation or event that overwhelms a community’s local capacity, necessitating external assistance. Some examples of human-made and natural disasters include war, industrial accidents, hurricanes, tsunamis, floods, and earthquakes. Floods are the most common natural disaster worldwide, accounting for 40% of all natural disasters. Populations affected by floods are at a particularly high risk for infectious diseases because of the difficulty in obtaining clean, potable water as well as the increased prevalence of vector-borne diseases that thrive in damp, crowded conditions. With increasing globalization, victims of a disaster may turn up in emergency departments hundreds of miles from the original site.
Infectious disease outbreaks may occur days, weeks, or even months after the initial disaster. It is important to realize that the conditions experienced in disaster zones are generally not new diseases but preexisting endemic diseases that become uncontrolled after disruption in community structures, including the following :
Disruption in water supply and sewage disposal: diarrheal illnesses (e.g., cholera, shigella, and Escherichia coli infections)
Displaced populations and overcrowding: respiratory infections (e.g., measles, influenza, pneumonia)
Disruption in ecological systems: vector-borne diseases (e.g., malaria, dengue fever, typhoid fever)
Disesases from trauma and reconstruction activities: skin and soft tissue infections (e.g., tetanus, methicillin-resistant Staphylococcus aureus [MRSA])
The capability of a health system to tackle a potential disaster can be defined by its vulnerability, which reflects its level of exposure to risk, shock, and stress. A community may be more vulnerable because of poverty, gender, age, ethnicity, comorbid conditions such as HIV/AIDS and malnutrition, or religious identity. Exposure to warfare, destruction of property, and direct attempts to undermine care to the afflicted may also make a system less functional. The ability to handle such factors may be referred to as resilience, or the ability to recover from adversity. Resilience can be increased, and vulnerability lessened, with disaster preparedness planning and appropriate external support.
History provides numerous examples of war and natural disasters resulting in widespread infection and mortality. In 31 bc , Marc Antony stationed his army, estimated at 30,000 men, on the hills above the marsh-bound city of Actium, Greece, in preparation for his invasion of Italy. Octavian, his rival, quickly encircled the city and camp on both land and sea, preventing supply wagons from entering and diverting the city’s supply of freshwater. Such tactics sent the soldiers and the people of Actium into the mosquito-infested swamps to find nourishment. Within 30 days, Antony had lost more than one third of his army to disease and malnutrition, and Octavian soon became Augustus Caesar. As recently as the twentieth century, army commanders expected to lose more soldiers from infectious diseases than from combat. Although widespread infectious diseases may have been simply part of life in the preindustrialized world, we now have the knowledge and capability to prevent such epidemics. Nevertheless, hundreds of thousands still die annually because of lack of appropriate planning and sufficient resources during and after major disasters.
On January 12, 2010, Haiti, the poorest country of the Western hemisphere, experienced one of the most devastating natural disasters in recent history. A 7.0 Richter-scale earthquake whose epicenter was located in close proximity to the densly populated capital and economic center of Port-au-Prince caused over 200,000 deaths and left over 1 million people homeless. Approximately 30,000 of the postquake deaths were due to infectious diseases from infected wounds, pneumonia, and diarrheal illnesses such as cholera. Examples such as this are evidence of the havoc that disasters can still inflict on humanity.
Diarrheal illnesses are widespread in disaster settlements and can cause significant mortality. After the 2010 earthquake in Haiti, a cholera epidemic developed in the Artibonite department with over 100,000 cases reported and more than 1100 deaths. Cholera had been virtually nonexistent in Haiti before the quake, but became epidemic 9 months afterward because of inadequate water supplies and sewage disposal. The initial case fatality rate from patients during the epidemic was strikingly high at 6.4% but improved to less than 1% with subsequent increases in cholera treatment centers, oral rehydration points, and preventive education messages. , Studies of refugee settlements have estimated that up to 40% of deaths are attributable to diarrheal illnesses and account for more than 80% of deaths in children less than 2 years old. In Bangladesh, a country that experiences frequent flooding, a study analyzing water samples from taps, ponds, and wells after a storm found that 33% of samples were contamined with Vibrio cholerae . Reports of outbreaks of viral hepatitis A and E were also reported in communities in Banda Aceh, Indonesia, after the 2004 Indian Ocean tsunami and were attributed to inadequate sewage and sanitation systems.
Acute respiratory infections (ARIs) such as viral upper respiratory infections (URIs), influenza, tuberculosis, and pneumonia also rapidly spread in enclosed, poorly ventilated, overcrowded refugee shelters after disasters. After the 2004 Indian Ocean tsunami, respiratory infections were the most common infectious disease found in refugee settlements, with 27.8% of people receiving medical care for respiratory problems during the first 2 weeks after the tsunami. The high incidence of respiratory illnesses was thought to be due to dusty living conditions and overcrowding.
Skin and soft tissue infections are common, often due to contamination of traumatic wounds sustained in the immediate postdisaster period. Tetanus emerged as a serious problem after the 2004 Indian Ocean tsunami among the largely unvaccinated population in Banda Aceh, with 106 patients admitted to hospitals between December 2004 and January 2005 and an 18% case fatality rate. Vibrio and MRSA infections were also reported among victims of Hurricane Katrina.
Increased prevalence of vector-borne diseases after disasters has been well described in the literature. Vectors such as mosquitos, flies, lice, mites, and rodents quickly multiply in crowded settlements. In 1997, a prolonged drought struck the Australasian region of Indonesia; a retrospective investigation revealed that increased standing water and food shortages resulted in a substantial movement of highland populations with low immunity to Plasmodium falciparum to low-lying coastal regions, which led to numerous deaths due to malaria. Subsequent evaporation of stream beds and mass antimalarial drug distribution resulted in a sharp decline in mortality. Moreover, during massive flooding in Brazil in 2008, 57,010 cases of dengue fever were reported, thought to be due to disruption in water supplies and solid waste management services.
A study in 2012 reviewing the major natural disasters during the years 2000-2011 found that the key risk factors for communicable diseases were population displacement from nonendemic to endemic areas, overcrowding, stagnant water, insufficient or contaminated water and poor sanitation, high exposure to disease vectors, insufficient nutrient intake, low vaccination coverage, and injuries.
Even industrialized nations are not impervious to infectious disease outbreaks. Hurricane Katrina hit the Gulf Coast of the United States on August 29, 2005, forcing the displacement of over 1 million people. Federal, state, and local health departments deployed medical teams and implemented infectious disease surveillance in evacuation shelters. Despite these efforts, more than 1000 cases of norovirus emerged over a period of 11 days in the Reliant Park Complex mega-shelter housing more than 27,000 people in Houston, Texas. Although the norovirus outbreak was the only communicable disease outbreak reported in the aftermath of Hurricane Katrina, the outbreak serves a reminder of the difficulty of containing infectious diseases even in settings with advanced medical resources.
Today’s disaster response encompasses a large scope of actions to prevent and control the spread of infectious diseases. Described below are some of the key practices that must be followed to prevent and control infectious diseases in any disaster response effort. A widely used resource for relief workers is the Sphere Handbook, Humanitarian Charter and Minimum Standards in Humanitarian Response , which details necessary interventions in living conditions to reduce the spread of diseases caused by crowding, unsafe water, and inadequate sewage. These interventions include the following:
Identification and maintenance of clean and adequate water supply. Providing continuous, adequate amounts of clean water is essential to the prevention of the spread of pathogens via the fecal-oral route, such as noroviruses and V. cholerae . Sources of water vary, depending on the geography and resources of the region, but generally come from surface water (lakes, ponds, rivers) or groundwater (wells, springs). Early involvement of sanitation and water supply engineers is essential for identification of water sources of acceptable quality and proximity to dwellings to ensure adequate water for cooking, drinking, and basic personal hygiene. Sanitary inspection of the water source is done to assess water quality (optimally, 0 to 10 fecal coliforms per 100 mL of water) using a field test kit or a local laboratory. Most commonly, water is distributed to large groups via a handpump or piped distribution method. If water treatment is needed, chlorination is the most effective method of disinfection, and water safety can be measured by determining the level of chlorination at the point of water collection or even in the bucket used for water collection (adequate levels are > 1.0 mg/L of chlorine). Relief efforts often dispense water collection containers to households to encourage safe water usage and storage.
Proper sanitation and sewage disposal. Usage of containment facilities for excreta, such as latrines, has been shown to offer the greatest protection from diarrheal illness over any other form of intervention. In the immediate phase (hours to days) after a disaster, trenches or open-defecation fields located downhill from settlements and away from water sources may be used until latrines have been constructed. Latrine construction is undertaken by sanitation engineers, aid workers, and community members to ensure they will be used by all members of the community. Failure to involve community members in the development of sanitation facilities will often result in people using alternative areas for fecal and solid waste disposal. increasing the risk of contamination of food and water supplies. Special consideration should be given to the needs of women and girls as they face risk of assault if facilities are not placed in safe locations. Per Sphere guidelines, latrines should be shared by no more than 20 people, located conveniently near dwellings (so they may be used at any time of day), and comfortable and culturally appropriate (designed by community, segregated by gender or family). Pit latrines—the most commonly used type of latrine in disaster relief—must be located > 30 m from any groundwater source. Education is essential for the community to accept usage of latrines as well as to ensure handwashing afterward.
Overcrowding prevention. Overcrowding and poor ventilation lead to spread of respiratory-borne illnesses such as measles and influenza. Housing construction and settlement planning should ensure that every person has at least 3.5 m 2 of living space. Dwellings should be constructed in a way that reduces the amount of smoke exposure from cooking fires.
Vector control. Assessment of populations’ underlying immunity and possible exposure to vector-borne diseases should be carried out with the help of local governments and aid organizations to identify risk factors that may be mitigated. Vector control includes reduction of vector breeding environments as well as personal protection for individuals. Mosquito breeding sites such as standing pools of water can be eliminated by draining or filling. Water storage containers may become vector breeding sites, so containers with lids should be provided. Populations at high risk for malaria and mosquito-borne diseases may receive mosquito nets and mosquito repellants to limit exposure. Chemical insecticides are only used when environmental controls are insufficient. Options include larvicides (destruction of eggs and larvae) applied to breeding sites, indoor residual spraying (spraying of long-lasting insecticide to walls of dwelling), insecticide-treated mosquito nets, and outdoor space spraying (reserved for situations in which large numbers of vectors must be eliminated quickly). Proper disposal of solid waste and sewage (see above) will also reduce possible breeding sites of insects and rodents. Controlling rodent-borne diseases includes storing food in rodent-proof containers and containing solid waste so these areas do not become breeding grounds. Usage of traps and rodenticide is less effective and can be dangerous, especially in settlements with many children. Control of lice and mites includes laundering the entire household’s bedding in hot water, delousing with insecticides, and regularly airing bedding. , The appropriate vector control measures are undertaken with the assistance of national and international vector control experts.
Personal hygiene. Education is the most important step in ensuring personal hygiene. Community members are enlisted to assist with culturally appropriate hygiene promotion, as well as educating the public on disease transmission and prevention. Handwashing facilities with soap and water should be readily available and usage encouraged after using latrines, before cooking, and for prevention of the spread of respiratory illnesses. Basic hygiene provisions include at least 250 g of bathing soap and 250 g of laundry soap per person per month, as well as sanitary materials for women to use during menstruation.
Wound care. Wounds from injuries due to the disaster itself (lacerations, amputations) as well as those sustained during reconstruction and cleanup efforts should be addressed by trained health workers familiar with proper cleaning and dressing of wounds. Basic first aid should be readily available at easily accessible local health units. Tetanus vaccines should be administered to anyone with dirty wounds or those at high risk from working in rescue or cleanup activities.
Disaster preparedness and response to infectious disease outbreaks generally occur at multiple levels—local, state, federal, and international. Local and state agencies play the main role in the response to disasters by performing situation assessment, organizing emergency medical services, obtaining fire department and law enforcement involvement, assigning and deploying resources, collecting data, and contacting federal and other agencies when assistance is needed. The Federal Emergency Management Agency (FEMA) works only at the request of a state government to assist with large disasters. The Centers for Disease Control and Prevention (CDC) also serves as the lead federal agency for disease surveillance and epidemic response. Several departments within the CDC work together to quickly assess an outbreak and prevent its spread. The Health Alert Network (HAN) is the primary method of quickly conveying information regarding urgent public health incidents among federal, state, and local health practitioners as well as public health laboratories. A rapid response team is sent to investigate, confirm the presence of infectious disease, and assist in the control of the outbreak. The Laboratory Response Network (LRN) provides laboratory testing, identification, and creation of effective treatment protocols. The National Electronic Disease Surveillance System (NEDSS) enters, updates, and electronically transmits demographic disease data to allow rapid reporting of disease trends in an effort to prevent outbreaks.
The Strategic National Stockpile (SNS) program is a repository of antibiotics, antidotes, antitoxins, life support medications, and other medical and surgical supplies that may supplement and supply state and local health agencies in the event of an infectious disease outbreak. The SNS may be deployed once the affected state has requested assistance from the CDC. Initial deployment consists of “push packages,” which are caches of pharmaceuticals, antidotes, and medical supplies designed to address a variety of agents and ready for delivery anywhere in the continental United States within 12 hours; however, the actual delivery time of these essential supplies may be delayed considerably by disruptions in transportation systems. Although not a first-response tool, the National Pharmaceutical Stockpile (NPS) may be needed to augment state and local agency supplies. If additional resources are needed, followup vendor-managed inventory supplies can be provided within 24 to 36 hours and can be tailored to the specific needs of the state.
As an operational organization of the United Nations, WHO acts as the directing and coordinating authority on all international health activity. WHO provides immediate care anywhere in the world when disaster and infectious disease have overrun the local resources of a country. In 2003 a devastating earthquake shook the city of Bam in Iran, killing as many as 30,000 people. With most hospital and health centers destroyed and approximately 80% of all buildings damaged, local and neighboring health facilities were overwhelmed by the needs of the 100,000 residents of the Bam area. WHO completed a rapid health assessment and immediately became involved in the provision of food, clothing, sanitation, and medical supplies. Their surveillance systems have also documented infectious diseases and further morbidity and mortality in the area. Weekly assessments available to the public on the WHO website allowed for identification of potential outbreaks and better allocation of resources to areas of need. Three weeks after the earthquake, there were no new outbreaks of disease and the incidence of diarrhea and other infectious diseases returned to predisaster levels.
Numerous international humanitarian organizations exist to provide rapid assistance in preventing and controlling infectious disease outbreaks in disaster zones. Well-established humanitarian organizations that respond to disasters worldwide include the International Committee of the Red Cross (ICRC) and Médecins Sans Frontières (MSF). National Red Cross societies exist in 178 countries, providing local care and international aid if requested by the ICRC. The mission of the ICRC is to “protect the lives and dignity of victims of war and internal violence and to provide them with assistance.” MSF was established to provide international emergency medical care, with its volunteers often being deployed to the most remote and unstable parts of the world to provide care to victims of both human-made and natural disasters. They can provide medical or surgical care, nutrition, sanitation, and local health training quickly and efficiently throughout the world. MSF was awarded the Nobel Peace Prize in 1999 for its efforts in emergency medical care. These and many other organizations often work together with the United Nations and WHO to provide care in complex humanitarian emergencies.
Countries with proper disaster management strategies in place are likely to be the most resilient when faced with a disaster, both during and immediately after. The Great East Japan (Tohoku) earthquake of March 2011 was one of the strongest recorded earthquakes in the history of Japan. Whereas the tremors themselves created relatively little damage, the subsequent massive tsunamis, as well as the infamous Fukushima nuclear power plant malfunction, created havoc, displacing more than 400,000 people from the northwest region of Japan. There were no significant infectious disease outbreaks recorded despite this huge population displacement. This result is attributable to the timely and planned response of well-trained medical and public health personnel, rapid distribution of supplies to the victims of the disaster, and an advanced disease surveillance system that enabled daily surveillance for outbreak detection in 40 large evacuation centers, as well as education on basic hygiene.
Disease surveillance and the investigation of early signs of disease are essential to preventing infectious disease outbreaks from becoming epidemics. Large-scale monitoring systems must be instituted at the initiation of a disaster response to recognize infectious diseases and to identify sources of diseases. After the 2010 Haiti earthquake, MSF conducted public health surveillance through data collection on patient visits at MSF-run outpatient sentinel sites. Acute respiratory infections and diarrheal illnesses were among the most common causes for visits, but the surveillance system also was designed to generate alerts for suspicious clusters of diseases. This alert system allowed MSF to identify a cluster of acute jaundice cases as being caused by an outbreak of hepatitis A.
Vaccination in disaster settings has also been used with promising results in several situations. Measles vaccinations have been shown to be a cost-effective intervention in refugee settings. A 2013 trial of distribution of a cholera vaccine in the Mae La refugee camp in Thailand housing ethnic Karen refugees from Burma showed some early success—as of 2014, no additional cases of cholera had been reported. Further research into the efficacy of vaccine campaigns in other disaster zones is required to evaluate for possible roles for influenza, hepatitis, and tetanus.
The importance of informing and mobilizing the public cannot be overemphasized. Television, radio, cell phones, and the Internet can disseminate vital information from local, state, and federal agencies to large numbers of people in a short amount of time. Public health campaigns to educate people on the importance of hygiene, clean water, and routes of transmission of infections can decrease the spread of diarrheal illnesses as well as sexually transmitted infections.
Infectious diseases in disaster zones are a preventable cause of significant morbidity and mortality in communities already facing devastating losses. Natural disasters may be unavoidable, but we can reduce further calamity by improving epidemic preparedness. By installing effective surveillance systems to track infectious disease incidence; ensuring basic standards of water safety, sanitation, and living conditions; and providing multidisciplinary rapid response personnel including public health workers, medical professionals, and sanitation engineers, we have shown we can effectively tackle even overwhelming challenges. As evidenced by the overwhelming worldwide humanitarian responses to the 2004 Indian Ocean tsunami and the 2010 Haiti earthquake, steady progress is being made toward controlling disease in areas where this was once considered an impossibility.