To be used in conjunction with
Pan American Health Organization
Scientific Publication No. 420

PAN AMERICAN HEALTH ORGANIZATION
Pan American Sanitary Bureau, Regional Office of the
WORLD HEALTH ORGANIZATION
525 Twenty-third Street, N.W.
Washington, D.C. 20037, U.S.A.

Disaster
Management Center
UNIVERSITY OF WISCONSIN-EXTENSION
Engineering and Applied Science
432 North Lake Street
Madison, Wisconsin 53706

608-262-2061 Telex No: 265452

Answer Key - Epidemiologic Surveillance

Disaster Development Problem - Flood

Note:Page numbers cited refer to Pan American Health Organization Scientific Publication No. 420, Epidemiologic Surveillance after Natural Disaster.

(A-1) Any three of the following answers are acceptable:

1. Changes in preexistent levels of disease

Usually the risk is proportional to the endemic level prior to the disaster. There is generally no risk of a given disease when the organism which causes it is not present beforehand, unless it is introduced by relief workers or supplies.

2. Ecological changes caused by the disaster

Vector-borne and water-borne diseases are the most significantly affected.

3. Population displacement

Movement of populations may affect the relative risk in three ways: (1) facilities and services of the receiving community are strained (2) the displaced population will encounter diseases not prevalent in their community and (3) displaced populations may bring agents or vectors with them.

4. Population density

This is a critical factor in the transmission of diseases spread by the respiratory route and through person-to-person contact.

5. Disruption of public utilities

Electricity, water, sewage disposal, etc. may be interrupted after a disaster. There is greater potential risk of water- and food-borne disease outbreaks in developed areas which are more dependent on these services than in less developed ones which are less dependent and probably have a higher level of natural immunity.

6. Interruption of basic public health services

Basic services such as vaccination, vector control, etc. are interrupted and for financial or other reasons may not be reestablished at sufficient levels. An outbreak may occur months after the disaster.

(A-2) Any two of the following answers are acceptable:

1. Migration of rural populations to congested areas

The present pattern of reaction to many disasters is one in which people congregate for food, safety, and medical attention. The more rural and isolated migrants usually have a greater susceptibility to common communicable diseases and are less likely to have received childhood immunizations.

2. Migration of urban populations to rural areas

This occurs more rarely than the situation above, but involves the risk of greater exposure to vector-borne diseases, particularly malaria.

3. Immigration of susceptibles to affected areas

Poorly briefed, underprovisioned international relief workers entering the disaster area are at risk. Established relief agencies are aware of this, but ad hoc voluntary groups may not be.

(A-3) Correct Answers:

I - inappropriate

The need for coordination of efforts after disaster with the normal surveillance activities in the health sector must be emphasized. The usual impulse after disaster is, however, for relief authorities to set up a separate postdisaster surveillance/assessment system.

I - inappropriate

Any attempt to establish a traditional surveillance system in an affected area during the immediate postdisaster period is fruitless.

I - inappropriate

Since unofficial reporting systems may still be operational, they should be exploited to the fullest extent possible. Intelligence (albeit frequently in the form of rumors) spreads from affected areas extremely rapidly via the media, survivors, and relief officers returning from the field.

A - appropriate

Surveillance information from ad hoc relief sources is critical in disaster-struck areas which lack a preexisting mechanism of surveillance.

I - inappropriate

Under some circumstances, the decision to institute a symptom or symptom complex reporting system for common conditions may be taken, rather than attempting etiologic diagnoses. Use of case definitions and symptom complexes must be standardized throughout the relief effort.

(A-4)Any three of the following answers are acceptable:

1. The slope of the land and nature of the soil should favor easy drainage.
2. There should be protection from adverse weather conditions
3. Sites should be away from mosquito breeding places.
4. Sites should be away from refuse dumps.
5. Sites should be away from commercial and industrial areas.

(A-5) Correct Answers:

I - inappropriate

A potentially more serious operational problem exists when local or national authorities deny rumors which have not been investigated.

A - appropriate

To confirm and/or quantify the magnitude of a problem indicated by rumor, the epidemiology staff should try to canvass reporting units in the area by radio.

A - appropriate

Immediately dispatching a team to look into the report is the quickest and most visible and effective response available.

I - inappropriate

Neither gamma globulin nor influenza vaccine is recommended for mass immunization after disaster. Efforts to achieve mass vaccination in the relief phase also drain whatever limited manpower, communication facilities, and transportation exist.

I - inappropriate

Not all notifiable communicable diseases can be diagnosed with confidence on the basis of clinical criteria alone.