3.3. Relationship between typhoid fever and
environmental factors
The decrease in the fatality rate was accompanied by
an increase in the percent pharmacy saturation in the
early 1960s. The stationary step then began in 1968, and
there was a 1% fatality rate for the next 8 years. The
second decrease in the fatality rate was accompanied by
an end in the decrease of the incidence rate. The decrease
in the incidence rate was also accompanied by increases
in the percent pharmacy saturation and the water service
coverage from 1971 to 1973 (Figure 1). However, the
water service coverage might be a more influential factor
in the decline of the incidence of typhoid fever, although
the correlation coefficients for water service coverage
(rZ0.84) were similar to that for pharmacy saturation
(r Z 0.85) from 1969 to 1977 (calculated using MS
Excel, Microsoft, Redmond, WA, USA).