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close this bookDisasters: Preparedness and Mitigation - Issue No. 019 - April, 1984 (PAHO; 1984; 8 pages) [ES]
View the documentEmergency medical supply management
View the documentLessons learned - Health effects of El Niño in Peru
View the documentMember countries
View the documentUpcoming meetings
View the documentReview of publications
View the documentNews from PAHO/WHO and other agencies
View the documentSelected bibliography

Lessons learned - Health effects of El Niño in Peru

Dr. Al. Gueri, PAHO

At the end of each year a weak warm sea current develops along the coasts of Peru and Ecuador, causing the surface temperature of the water to rise. When the temperature increases considerably more than normal, it causes significant changes in the distribution of atmospheric pressure. When the cold water that normally rises from the depths disappears, the event called El Niño occurs (thus called by local fishermen because it happens around Christmas-the coming of the Child). As a result, atmospheric abnormalities occur along the Eastern and Western Pacific.


From late 1982 until mid 1983 this atmospheric phenomenon caused the worst flooding that Peru has known in 50 years. Table I shows the average rainfall for the months of January-June from 1973 to 1982, compared to 1983.

The departments that suffered the greatest damage were Piura and Tumbes, in the northern part of the country. Both departments are divided into two geographic zones: a wide coastal belt with a desert climate, and a mountainous zone formed by the western extension of the Andes.

Inhabitants of Trinidad, Bolivia, paddled through town in canoes after floods made normal transportation impossible. Photo: J. Muñoz Pazmiño/LICROSS

Because the coastal area where most of the people live is usually dry, neither roads nor cities nor buildings are constructed to resist intense rain. The main highways were cut off at several points while other roads were turned into mud or submerged in recently formed ponds. Streets had become small rivers. Adobe constructions fell apart in the rain and even those houses made of more resistant material were severely damaged.

Table 1: Average rainfall at 18 meteorological stations in Piura and Tumbes*






















* Data provided by the National Meteorology and Hydrology Service (Peru).

The distribution of food, medical supplies and fuel was sharply curtailed. The fuel shortage was critical and transportation was effectively paralyzed in both departments. The isolation of the populations was even more intense in the agricultural mountain areas, from which food could not be transported to the markets.

Effect on health services

Health services also were affected strongly, especially the delivery: the population could not reach the health posts and groups of physicians and paramedics often could not get to the communities in need of help because of the disruption of transportation and lack of fuel.

The destruction of housing caused population shifts in the larger urban areas, giving rise to temporary settlements. The temporary housing was made of typical materials like wood planks and zinc, mixed with tents distributed by the Red Cross and Civil Defense. Some of these were erected near garbage dumps and mosquito breeding sites. The sewerage system, where there had been one, had been destroyed and the water supply system was damaged.

The population was unaccustomed to facing conditions of this kind. Every day residents had to bail the water out of their houses before starting the walk through mud to their jobs, paying high prices to speculators selling food and other basic necessities, and returning to their homes where there was no running drinking water, drainage or sewerage system.

Thus, starting in December 1982, the factors that tend to increase the risk of disease transmission after disasters gradually accumulated: ecological shifts that cause changes in the density of vectors, population displacements (within limited areas), and the disruption of public services and of some of the basic health and environmental hygiene services.

Surveys of health impact

In general, WHO's experience has demonstrated that serious epidemic outbreaks do not tend to occur after natural disasters. According to the information that could be obtained at the time, the first assessment of damage to the health sector in both departments carried out by the author with representatives of the health ministry in early February 1983, showed no evidence of marked changes in the health status of the population.

However, the rumors that always arise after disasters increased, and some of the data that were received by the Ministry seemed to indicate that the incidence of selected diseases had gone up. This was confirmed during a second assessment visit that was made in April 1983.

Preliminary data from a retrospective study carried out by the Ministry and PAHO show that there was an increase in demand for medical care. What is even more significant is the reported proportional increase in demand for specific diseases and among specific age groups at the expense of others. The proportion of children with diarrhea, dehydration and respiratory ailments rose, while admissions for chronic diseases, cardiovascular problems and routine "programs" (well-baby visits, prenatal care and family planning) all declined. We still do not know whether this selection process was "natural" or whether the health centers instituted a triage system when they were overwhelmed by the increase in demand for care.

Table 2 shows the preliminary results of the study regarding the number of cases attended in four health centers. Table 3 illustrates the frequency distribution of cases according to diagnostic group.

Table 2: Medical care, January-June 1982 and 1983*


Age groups



Under 5 years of age

Over 5


























* Preliminary data from the health centers of Castilla, Catacaos, Talara and Santa Julia.

Table 3: Frequency of cases



































(1) UNDRO: "The Major Pacific Warm", UNDRO News Sept. Oct. 1983. Pg 10-14.

(2) Western, K. "Epidemiologic Surveillance after Natural Disaster." PAHO Scientific Publication 420, 1982.

In the four health centers analyzed to date the total increase of admissions in the first six months of 1983 was 100% over the same period in 1982. In the group of children under 5 years of age, however, the increase was 126.4%, while in the group over 5 years old it was 82.3%. Similarly, in 1982 gastrointestinal, respiratory and dermatological disorders represented 49.2% of admissions, while in 1983 they accounted for 65.5% of all cases attended.

These results are preliminary. The final report on the data and conclusions that may be drawn from them will be published comprehensively when the analysis has been completed.

Deployment of medical assistance

Other institutions made an effort to cover the demand that could not be handled by the health ministry. The Social Security Institute, for example, sent a total of 38 doctors, 29 nurses, 10 obstetricians and 28 technicians from Lima to rural areas of Piura and Tumbes for a period of 4 to 13 days from March 3 to July 11. This was the equivalent of 249 doctor/days in which 10,874 patients were treated.

The Navy sent three teams of six physicians during the period of May 3 to August 8 (representing 198 doctor/days); 22,000 patients were attended in shantytowns and isolated rural areas.

The Red Cross set up a medical care station at its offices in Piura, where 20 doctors offered volunteer services for varying amounts of time; 7,761 patients were seen between January and June (an average of around 60 patients per working day). The 249 doctor/days given by the Social Security Institute averaged 44 cases per doctor/day while the 198 doctor/days of the Navy averaged 111 patients per day.

The variation in the number of patients seen daily by the different services can be explained by the geographical location in which they operated. The Navy concentrated on highly populated areas (shantytowns) and isolated highland villages, because they had the logistical support of the armed forces (especially helicopters). The Red Cross was limited to an area in the center of the city of Piura, which was relatively near the regional hospital. The Social Security Institute, meanwhile, concentrated on partially isolated rural areas in which the population density was low.

To what extent the special effort made to mobilize health teams to care for the population affected the increase in reported diseases has not yet been determined. Clearly, the fact that medical personnel were there actively looking for cases, could partially explain the marked increase in the reporting of the diseases listed in tables 2 and 3.

In Bolivia, as in Peru, severe floods disrupted the routine delivery of health care, especially in outlying rural areas. Photo. J. Muñoz Pazmiño/LICROSS

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