80 



INSTITUTE OF SOCIAL ANTHROPOLOGY — PUBLICATION NO. 1 1 



tively few deaths tend to have the greatest de- 

 parture from the norms in the monthly distribution 

 of deaths. This would indicate that the seasonal 

 incidence of the more lethal diseases determines 

 the norms of distribution. The mortalities can 

 be distributed along a fairly smooth curve which 

 begins with December, January, and February (the 

 season with fewest deaths), swings up slightly in 

 March and yet more in April, runs strongly up- 

 ward through May and June to a climax in July, 

 falls off somewhat in August and September, and 

 continues downward in October, although there is 

 a slight upward movement in November before 

 completing the cycle into December. 



The gastrointestinal diseases (including dysen- 

 tery) are most common from April to August, 

 with a peak in June-July and a minor peak in 

 November. Typhoid and paratyphoid fevers are 

 most prevalent in July, August, and September. 

 The e.xplanation of this coincidence with the 

 summer period is that the heavy rains commonly 

 begin toward the end of June, and for 2 or 3 

 months the sources of potable water are strongly 

 polluted. As the filth that has accumulated 

 during the dry season is leached out and evacuated 

 from the soils the waters in the springs, wells, 

 and streams become cleaner and the incidence of 

 water-borne infections decreases. Diseases of the 

 respiratory tract are most manifest during the 

 relatively cool and dry season, or winter, from 

 November to May, with a peak in April. Although 

 modern incidence of smallpox, whooping cough, 

 and typhus, tends to be low and scattered, the 

 records over the longer period show the strongest 

 concentrations of deaths from these diseases in 

 the November to May period. Malarial deaths 

 are most common December to June. It formerly 

 was assumed that after the uinter and spring 

 attacks of smallpox would come the scourge of 

 measles, and there is still a tendency toward 

 concentration of measles between April and 

 September. Perhaps because of the general 

 debihtating effect of the water-borne infections 

 more than half of other deaths (such as senile 

 exhaustion, cachexia, and deaths of unknown 

 cause) occur in the May to August period. 



AGE AND DEATH 



Throughout the medical history of Mexico and 

 of Michoacdn the infant (less than 1 year of age) 



mortality has been exceedingly high. This con- 

 dition obtains in Quiroga, where usually at least 

 one-third of the deaths in any year are of infants 

 under 1 year of age, and where in more than half 

 of the years children under 4 constitute more than 

 half of the deaths. Some changes in age distri- 

 bution of deaths are indicated by table 17, which 

 shows the raw figures for the 1867-77 and 1937-45 

 periods. 



Table 17. — Deaths by age groups for 1867-77 and 1937-46 



The principal change between the 1860-70's 

 and the 1930-40's has been a lowering of the 

 proportion of children's deaths (from 62.78 percent 

 to 52.97 percent), which has been accomphshed 

 chiefly in the 13-month to 3-year group since the 

 proportion of infant deaths has increased. Our 

 data conform fairly closely with the national per- 

 centage of 47.4 and that for Michoacdn of 46.7 

 (computed for 1937-39) comprising children under 

 5 years of age. For the period 1940-45 there 

 were 150 infant deaths per thousand infants less 

 than 1 year of age, which can be compared with 

 the Mexican rate of 116.6 in 1943. It is evident 

 that the critical period is from birth until the 

 fourth year of age. Other than those who die at 

 birth or without diagnosis, the majority of children 

 under 15 in Quu'oga die from diarrhea and enteritis, 

 bronchitis and pneumonia, iniluenza, measles, 

 whooping cough, and dysentery — in that order. 

 Probably the diseases of the digestive and respira- 

 tory organs account for more than half of the 

 deaths of children. In recent years smallpox, 



