Preventive Medicine in Humanitarian Emergencies

Why is Preventive Medicine and Public Health Important after a Disaster?

In a post-disaster scenario, health workers are faced with many challenges. For example, they may be concerned for the safety and well-being of their own families as well as the health and well-being of their patients. Most will have an innate desire to help their community. Depending on the specific scenario, pediatricians may have to use skills that are beyond those of everyday practice, such as trauma care in the immediate aftermath of an earthquake. However, in any disaster situation, preventive medicine and public health techniques are likely to be most useful aspects for overall community recovery.

Preventive Medicine: A Public Health Mindset

In clinical practice, physicians spend most of their time diagnosing and treating patients one at a time. Most health care is focused on caring for the patient. Preventive medicine, rather than trying to help the individual patient, focuses on the underlying causes of illness in society and employs public health techniques to address these problems at the population level (Box 1).

The preventive medicine “patient” is considered a group of people, a population, or an entire community with sub-groups within that community. The first step the transition from clinical practice to preventi­ve medicine is to understand your patient. In clinical practice, patients come for consultation with the clinician one by one. Vital signs are determined, and the history, physical examination, and perhaps laboratory tests are used to arrive at a diagnosis and rational treatment plan.

Rates facilitate the comparison between the reality of one community and that of others. They also help assess through time the success of interventions in a given population.

Population Health Evaluations Including Emergency Needs Assessments

Population Evaluation

Pediatricians can facilitate post-disaster recovery in their communities by helping to assess local population conditions. It is important to obtain as much hard data as possible – do not depend on speculation. Too often, disaster relief efforts are hindered and resources squandered by well intentioned people acting without the background of sound epidemiological data. Box 6 describes the components of a population evaluation.

Demographic Data

In a disaster, collecting data on population characteristics (number, age groups, ethnicity, gender) is critical. The crudest form of counting people is by air. This is by far the least accurate way of assessing the scope of a disaster, but it may be all that is possible in some situations. Visual estimates from the ground may be used as well to get a quick count of the affected population.

More accurate method to assess the affected population and its structure is by using standard sampling techniques, such as systematic household sampling. The most accurate way to gather demographic information is to count all individuals and list them by age group and sex. Vulnerable groups (such as children under 5 years and/or without a family, breastfeeding mothers, pregnant women, the elderly, and the injured) need particular attention and must be identified. 

Although counting people and rate demographic data, it will be difficult to determine the true nature of what is happening in a community, and scarce resources may be wasted.

Pre-disaster Health Conditions groups may be tedious, this is a top priority (Box 7). Humanitarian agencies such as UNHCR, WFP, OCHA register beneficiaries so consider obtaining population denominators from such agencies. 

Baseline Health Data and Preparedness

Pediatricians can maximize their disaster preparedness by being active in preparing community health plans and taking the lead in helping with community disaster drills. The ideal situation would be for all public and private health care workers to meet periodically to discuss community health problems and practice disaster drills. This would increase their knowledge of the community and its health problems, and would allow for relationships to be built between the public and private sector before a disaster strikes.

Emergency Needs Assessment

A needs assessment looks at what a community lacks as well as what resources and capacities it can use to address problems. The objective of a needs assessment is to identify gaps between current community needs and resources.

Emergency needs assessments (also called rapid needs assessments) are focused on those needs that can ameliorate the greatest amount of morbidity in the community (Box 8).

Security, transportation, and communication are also key elements of an emergency community needs assessment; however, these components may fall outside the traditional healthcare realm. They will be covered in greater detail under “Conditions of other community resources” at the end of this section.

Water

Water is critical to survival and must always be a top priority. The quantity of water is a higher priority than quality in the immediate post-disaster scenario. Providing clean water will do more to prevent the spread of disease than any other preventive medicine intervention. An estimates of water quantity needs only for drinking varies from 3 to 4 liters/person/day. However, the water needs will increase to 15 to 20 liters/person/day when cooking, cleaning, laundry, and personal hygiene are taken into account. The immediate identification of water sources, ways to protect these resources and methods to improve water quality are top priorities. Water purification systems may eventually be provided by relief agencies. If there are immediate concerns about the safety of the water, then it can be chlorinated by adding 2 drops of bleach (sodium hypochlorite solution) per liter of water.

Nutritional status

Nutritional assessments take into account community needs as well as local resources. Again data, not speculation, is needed. The recommendation for caloric needs in a displaced population is 2,100 Kcal/person per day. Other elements of the nutritional needs assessment include food availability, nutrition quality including availability of adequate micro-nutrients, food security, distribution throughout the community, and cultural factors that affect nutrition.

Common sampling techniques for surveying children’s nutritional status (or other health condition) include random selection (simple or systematic) or cluster sampling. Simple random selection can be done if all the children can be identified, such as by immunization records or a camp census. They are assigned a number and then a random number table is used to select those who will be evaluated for nutritional status.

Systematic random sampling is done by checking every nth household to get enough children for a representative sample. This is useful if the households are reasonably neatly ordered, such as ordered in rows of tents. The interval between each household that is sampled (n) is determined by the total number of households in the community divided by the number of households you wish to sample. For example, to check the nutritional status of children in 450 households out of a total of 2,800 households, you would check every sixth household (2,800 divided by 450). The first household to be sampled would be determined by randomly selecting a number between 1 and 6. Survey teams would then check the nutritional status of children in every sixth household, beginning with the randomly selected one.

Cluster sampling is a statistical sampling technique that is used for large numbers of people and is beyond the scope of this discussion. A public health professional with training in epidemiology or a standard text on this subject could be used to design a survey using cluster technique.

If random selection (simple or systematic) is used, a sample size of about 450 children is needed. If cluster sampling is used, the sample size should be of about 900 children for an accurate population estimate. If the community size is small enough, it is more accurate to simply check all the children who are in the sentinel population age range.

It is important to bear in mind that the sample size will depend not only on the population size but also on the frequency of the phenomenon being investigated; i.e., the prevalence of this phenomenon in the community.

Shelter

For shelter, the WHO recommends 3.5 to 4 squared meters (m2) per person as the absolute minimal amount of floor space for a displaced population. A rapid assessment of available remaining space will identify any disparity between needs and capacity. Predisaster planning should emphasize the use of community spaces such as schools, churches, and assembly halls for emergency shelter.

Basic sanitation

Basic sanitation is aimed at preventing spread of communicable diseases from indiscriminant defecation. Feces are a concentrated source of human pathogens and can lead to explosive outbreaks of diarrheal diseases. In a post-disaster scenario, effective control of human waste is a top priority. One person can contaminate water used by thousands, and flies can spread fecal material to food supplies, rapidly creating hundreds or thousands of cases of food and waterborne illness.

Local environmental conditions

Conditions that affect community health, such as smoke, chemical spills, floods, landslides, collapsed buildings, terrain slopes, drainages, and insect vectors, are all important to assess during disaster situations.

Health needs

The emergency assessment of health needs is focused on mortality rates and the chief causes of morbidity. Death is the most severe negative health outcome and it must be tracked carefully to understand what is happening in a community. To provide the most accurate information, mortality data should be reported by age, sex, and cause of death.

This data is captured by using patient logbooks or records that record age, sex and chief diagnosis of the patient. This data can be rapidly analyzed to gain an understanding of the chief health threats to the community and used to plan the use of resources accordingly.

Evaluation of Health-Care Resources

Evaluation of the health-care system requires pre-disaster knowledge of community resources. By joining with public health officials and disaster planning committees, pediatricians and other local physicians can be included in community health-care worker rosters and will learn where emergency medical supplies are stored. Organized plans for signaling an emergency and identifying a specific location to convene as a group would lead to rapid mobilization of all health-care workers in case of an emergency. Identifying additional areas for handling surge capacity and the staffing of these additional treatment areas is important. For example, with a pandemic influenza outbreak, current healthcare facilities can become overwhelmed. Identifying alternate care facilities in each community and regionally may be needed to meet demands. Predisaster planning by delegating responsibilities for assessing the condition of local hospitals and clinics and determining available medical supplies will avoid confusion and wasted efforts.

Disease Recording and Reporting

After a disaster, it is critical that all health-care workers, both private and public, join together to form an integrated and coordinated system that records and reports diseases. This is one of the most important roles of health workers who are engaged in a traditional clinical consulting mode. To the clinician who is working long hours trying to treat as many patients as possible, gathering data may seem like a waste of time, but it is crucial for planning disaster response.

Transportation and Communication Resources

Security

Epidemic preparedness and outbreak response

Modes of Disease Transmission

Post-disaster living conditions frequently enhance the transmission of infectious diseases. Understanding how these conditions pose health threats will help set priorities for public health interventions. The most common modes of transmission after a disaster are fecal-oral, respiratory, and vector borne. Fecal-oral transmission can occur by having human waste enter into the water supply by indiscriminant defecation or by flooding, by flies carrying feces on their feet to food sources, or from unwashed hands.

The respiratory route is enhanced by the crowded conditions that frequently follow a disaster. Also, respiratory irritants such as smoke from open cooking fires may increase predisposition towards the spread of respiratory pathogens. Vector-borne illnesses such as malaria and dengue frequently increase following disasters, particularly floods or hurricanes because standing water increases mosquito breeding.

Infections are usually referred to when the notion of transmission is being discussed, because infection transmission is easier to prove objectively. In contrast, the epidemiologic evidence of causality in the transmission of noninfectious ­diseases is more difficult to demonstrate. An example is lung cancer associated with cigarette smoking.

There are four modes of transmission of infectious diseases: contact, common source, airway transmission, and transmission by vectors.

Contact

This necessitates a connection between the host and the infectious agent that causes the disease. The contact can be direct, indirect or through droplets. Direct contact involves person-to-person contact, as in the case of the fecal-oral route, in which the microorganism contained in the feces of an infected person is transmitted, due to defective hygiene conditions, to another person, usually another household member. Examples: hepatitis A, Salmonella, Shigella. An additional example is the contact with a Staphylococcus aureus infected wound. Indirect contact is through an inanimate object. Example: hepatitis B, due to the shared utilization by family members of objects such as tooth brushes. Finally, the contact through droplets is the person-to-person transmission through droplets emitted by the mouth or nostrils. The longest distance that droplets travel in the air is approximately 3 yards. Examples: measles, chickenpox, streptococcal disease.

Common Source

A microorganism or a toxin can cause disease in one or several persons from a common source that contains the infective agent. Example: gastroenteritis outbreaks resulting from contaminated food (ice cream, mushroom sauce) (Box 9).

Transmission through the Air

Microorganisms can travel more than 3 yards in the air from the source of infection. Traveling microparticles usually result from the evaporation of drops emitted by the source of the disease. Examples: tuberculosis (through the cough of a diseased person), psittacosis (from a diseased fowl to a person), Q fever (from contaminated products; can travel several miles), and Legionella (through air-conditioning systems).

Transmission by Vectors

Transmission by vectors can be external or internal. In the external transmission, the vector carries the unmodified infective agent on its body. Example: flies carry Salmonella acquired from contaminated feces and deposit the bacteria on food that is later ingested by the host (human being or animal). In the internal transmission, the microorganism travels inside the body of the vector, where it may remain unaltered (Yersinia pestis is ingested and then eliminated unchanged) or may be modified, as in Plasmodium falciparum transmission by the mosquito.

Recognize that transmission can occur by one or several modes (Table 1).

Select to expand to see each transmission type. For printing, expand all sections before printing.

Post-Disaster Health Interventions

The objective of post-disaster health interventions is to minimize death and prevent excess disease. Another public health priority is to facilitate community preparation for future disasters. Ideally, all interventions are guided by a thorough emergency needs assessment and ongoing evaluation of the team’s effectiveness during a disaster situation.

Immediate public health interventions include the following priorities:

Provide Safe Drinking Water

Providing sufficient quantities of clean drinking water is usually the highest priority of all disaster relief efforts. Effective water purification programs will likely have a greater impact on community death and disease rates than any other single intervention. To be effective, drinking water programs must be accepted by the community, so factors such as taste and convenient access to the purified water source must be taken into account. For long-term planning, water purification programs must be sustainable by the community once the disaster is under control.

Simple field treatment of water may improve quality and decrease waterborne infections. Covering and allowing sediments to settle will improve the quality and decrease amount of chlorination needed to purify water. Sand filtration by allowing water to percolate through stones and sand contained in a 55 gallon barrel will also improve quality of water. Bulk chlorination, when available, is another way to provide clean water to large numbers of people. Reverse osmosis units, such as those used by military, can provide thousands of gallons of pure water but are expensive, require expertise to operate, and take many days to deliver to a community, costing valuable time.

Boiling takes time and effort. Cleaning water by adding bleach or chlorine at the household level relies upon motivation, efficient distribution of cleansing products, and most important, a fair amount of education to do it correctly.

Utilizing an effective distribution system is equally important as having clean water. No matter the quality of water at the source, it must arrive to the end users in some fashion. Clean, covered storage tanks are a top priority as well as a means to transport the water to community members.

Control Human Waste

Take into account the special needs of children when planning for community sanitation programs. Children are more likely to defecate indiscriminately and may not use a portable lavatory that is inconveniently located, frightening, or does not meet their physical needs. Soap and water for personal hygiene are a lower priority when compared with drinking water supply and the elimination of feces. However, after drinking water requirements have been covered, it will be important to provide soap and water for personal hygiene to prevent the spread of infectious diseases. A minimum of 7 liters of water per person daily is needed for covering hygiene requirements.

Protect Food Supply

Developing a plan for protecting the food supply should occur in disaster preparedness. Securing community resources and safely storing and protecting emergency rations are important details to work out in advance and should include all key agencies involved with disaster planning. Protecting food preparation from contamination is a high priority. Basic measures for preventing food-borne illness include:

Additionally, providing health ­education information may be necessary to help community members prepare and use food resources safely.

Provide Adequate Shelter

WHO recommends at least 4 square meters of floor space for each person in an emergency shelter. Shelters are more effective if they keep families and other traditional community groups together and are close to resources such as food, water, lavatories, medical care, and transportation. When homes are destroyed, it is far better to locate shelters as close to or within the pre-existing community whenever possible.

The Use of the Surveillance Cycle to Guide Use of Resources

Surveillance Cycle: A Powerful Public Health Tool

After the emergency assessment is completed and disaster recovery operations have started, ongoing surveillance will evaluate emerging population needs. Surveillance is defined by the U.S. Centers for Disease Control and Prevention (CDC) as “...the ongoing, systematic collection, analysis and interpretation of public health data essential to the planning, implementation and evaluation of public health practice, closely integrated with the timely dissemination of these data to those who need to know. The final link is the application of these data to prevention and control. A surveillance system includes a functional capacity for data collection, analysis and dissemination linked to public health programs.”

The surveillance cycle essentially consists of gathering data that are critical for monitoring ongoing health needs, analyzing and interpreting that data in a timely fashion, providing feedback to those who need to know, and taking actions based on these data (Box 10). After an action is taken, the cycle is repeated to re-evaluate the effectiveness of this action (Figure 1).

Pediatricians’ Role in Preventive Medicine

Pediatricians, whether in public or ­private service, can assist disaster recovery in their communities in many ways. These need not be limited to simply seeing children in consultation; with adequate preparation, pediatricians and other physicians and nurses can fill many important roles, from assisting with search and rescue efforts to conducting population surveys. Their effectiveness will largely depend on personal preparation and their integration into community pre-disaster planning strategies (Box 11).

Children form a large proportion of the population and because children are one of the most vulnerable groups during a disaster, it makes sense to have pediatricians serve as leaders in disaster response and preparedness programs. Drills should involve children as mock victims, and should represent the ages and numbers representative of the population at large. Advance planning for meeting children’s special nutritional, psychological, and developmental needs will likely happen only if pediatricians are involved in every aspect of disaster planning. By teaching other health workers, such as nurses, general practice doctors, and lay community health workers, pediatricians can disseminate their knowledge of children’s special needs throughout the disaster response community.

Pediatricians in private practice may need to go out of their way to meet with public health, military, and other governmental officials to offer their services in pre-disaster planning. Waiting to act “ad hoc” after a disaster strikes is a recipe for wasted effort and represents an inability to make a meaningful impact on community recovery.

Pediatricians and the Surveillance Cycle

Even if pediatricians work primarily in their traditional capacity of clinical consultation, they may still have a significant role to play in preventive medicine by making sure that a functioning surveillance cycle is in place. Crucial points of the cycle would include establishing an adequate patient logbook or record that captures important disease data and stratifies data to specific age and sex groups. This is where the surveillance cycle begins, with clinicians seeing individual patients. If they do not capture this data, public health decisions will be based on speculation, not facts.

Conclusion

References

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