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close this bookEmergency Vector Control after Natural Disaster (PAHO, 1982, 112 p.)
close this folderPart I: An Overview
close this folderChapter 3: Postdisaster action
View the documentImmediate Action
View the documentSurveillance and Control

Immediate Action

One of the first actions of the subcommittee should be to assess the potential of vector and rodent related problems, and to gather adequate baseline information. Vector and rodent control personnel should be consulted about the locations of temporary living quarters, so that human contact with these organisms is minimized. Vector and rodent control personnel, and sanitarians, c an also provide advice about mosquito and rodent proofing of temporary structures. It is also necessary at this time to determine if the available staff members, insecticide resources and equipment are adequate. If not, appropriate measures should be taken.

Assessment of Situation

A significant problem that administrators of vector control face after natural disasters is accurately assessing the potential of vector and rodent related problems, and determining what resources are required. A considerable amount of unreliable information concerning the vector problem may be generated from other than official sources. In most cases, it will be exaggerated and panic may result in the population. Accurate and updated information collected before a disaster facilitates the proper evaluation of the postdisaster situation and it aids in the process of making logical decisions concerning a plan of action. Such information also helps in providing international relief agencies a clear picture of the problems a disaster can pose. It permits them to reach a clearer definition of their role in relieving shortages of insecticides, rodenticides and equipment. Adequate information from the predisaster period also improves the accuracy of the information that is given to government information services and the local population.

Each of the different types of natural disasters causes specific kinds of vector and rodent related problems, and the periods of time in which they remain problematic varies. This is particularly true of water related disasters that create breeding habitats. Certain types of' information, which may be broken down according to type of disaster, are generally required in the postdisaster period. After all disasters, it is necessary to do the following:

(1) Determine the geographical area and the size and distribution of the population affected, and the political and medical zones involved

(2) Assess the extent of' damage to transportation and communication systems

(3) Determine the availability of staff', the availability and condition of equipment and supplies in the affected area, and the availability of' additional resources in unaffected areas

(4) Review the current information on the vector and rodent situation, including population densities in the affected area and the prevalence of vector and rodent related diseases in affected and adjacent areas.

After the specific occurrence of wafer related disasters, such as hurricanes, cyclones and floods, the following steps need to be taken:

(1) Determine all migrations and redistributions of human populations within and adjacent to the affected area

(2) Assess the extent of damage to the water supply system and sanitary facilities, and estimate the time required to restore these services

(3) Appraise the crowding and exposure to mosquitoes and other vectors in postdisaster living situations, and the rodent-ectoparasite contact and fly breeding as they relate to the living situations

(4) Determine the status of established mosquito breeding habitats and the extent to which new ones are created

(5) Work with epidemiologists and other health officials to reestablish the disease surveillance network and the role of the vector control programs within the network.

When earthquakes and volcanic eruptions occur, these steps should be followed:

(1) Determine population movements and the need for shelter, water and sanitation
(2) Assess the risk of vector and rodent-borne diseases
(3) Determine the need for vector control when there is emergency provision of' water and sanitation in the area.

Aerial observation, where available, is one of the easiest methods of obtaining information on the geographical extent of damage to population centers and communication and transportation systems. It is useful, as well, for assessing vector breeding potential and human population movements. Light, single and multi-engine aircraft and helicopters may be available from the military and private sectors or from commercial agricultural aerial spray companies. Funds for aerial surveillance should be allocated in any budget. Maps and, if available, recent aerial photographs can be used for comparative purposes when the situation is assessed.

Additional information may be obtained from on-site reports from vector control staff members who live or work in the area and from local public health inspectors, physicians, administrators and teachers. Some caution should prevail, however, when interpreting information from these sources.

Determining Priorities of Action

Knowledge of the biology and ecology of pest organisms and their relevance to the current conditions is required when the effect that natural disaster damage has on vector and rodent problems is assessed. For example, flooding usually flushes out or destroys mosquito breeding sites. It subsequently creates additional habitats that can eventually produce even greater mosquito densities. When water and sewage systems are damaged, increased storage of' potable water can provide additional breeding sites for Aedes aegypti while temporary pit latrines can provide habitats for synanthropic flies and Culex quinquefasciatus. Inadequate food storage, poor sanitation, and contamination by debris, animal carcasses and excreta may produce filth flies and increase the visibility of the rodent populations.

Problems related to vectors and rodents may not be confined to the affected region. Human movement away from the region may contribute to crowding in peripheral areas and, as a result, provide opportunity for proliferation of diseases associated with vectors and rodents. Following water related disasters, the peripheral areas may harbor potential mosquito breeding habitats that are more conductive as immediate oviposition sites than in the actual disaster area.

When setting priorities, types of vector-borne diseases in the area and density of the human population are factors to consider. When these are known, action should be immediately directed toward the areas of' high population density, especially slum areas and camps where migrant populations are received. Every attempt should be made to restore and strengthen routine vector control operations within the area.

Under certain circumstances, the Ministry of Defense may be called upon to render aid in the wake of a natural disaster. Probably no other organization is so uniquely endowed with the necessary resources such as manpower and transportation, and possesses the necessary capability of quick reaction.

Urban, suburban, and rural areas of high priority for receiving control efforts should be determined from the following criteria:

(1) Population at risk
(2) Number of confirmed or suspected disease outbreaks
(3) Recent history or disease transmission
(4) Relative density of potential disease vectors
(5) Significant increases in new breeding sites
(6) Significant wind damage resulting in destruction of sprayed houses and increased exposure of displaced or homeless persons to mosquitoes
(7) Presence of potential disease reservoirs
(8) Seasonal accessibility by ground transport
(9) Number and types of complaint calls regarding mosquito activity.

Surveillance and Control

The major activities in vector and rodent control occur during the postdisaster period. If the immediate surveys and other sources of information indicate a potential problem, the sot>ner that postdisaster programs arc implemented to reduce the disease potential, the less is the chance that epidemics will occur and the Iess is the overall expense to the government. Delaying action until an epidemic is at its height can be medically and economically disastrous.

Reestablishing and upgrading routine control operations,, surveillance activities and training of' staff members will go far in lessening the chance and/or impact of' en arthropod-borne epidemic. Operational manuals for control of malaria and Aedes aegypti caused diseases prepared by the World Health Organization and the Pan American Health Organization can assist in planning these activities.

Emergency Action in the Event of a Vector-Borne Disease Outbreak

Should the immediate action to bring vector populations under control prove insufficient, and a vector-borne disease outbreak result, all efforts should be made to reduce infective adult mosquito populations as soon as possible, by such space spray methods as aerial ultra-low volume (ULV) applications, vehicle-mounted and portable thermal foggers, aerosol generators or portable mist ultra-low volume blowers, Details about these methods art given in Part II. under "Specific Vector Problems."