|Community-Based Longitudinal Nutrition and Health Studies : Classical Examples from Guatemala, Haiti and Mexico (International Nutrition Foundation for Developing Countries - INFDC, 1995, 184 pages)|
|2. The Santa María Cauqué study: Health and survival of Mayan Indians under deprivation, Guatemala|
The Human Laboratory
The study consisted of a long-term prospective observation of all cohorts of mothers and infants of the village from 1963 through 1972. Such a "human laboratory" permitted biological and sociological data to be gathered on all child cohorts during the study period, although virtually every other person in the community contributed data at one time or another. Most treatments were prescribed in accordance with Western medical guidelines and ethics. The study favored observation of the natural course of infectious disease with little disturbance, a situation difficult to replicate today.
The Health Clinic
The first year (1963) was devoted to getting acquainted with authorities, leaders, and village folk. The treatment protocol and standard operation procedure for field and laboratory were produced and tested. Virtually every pregnant woman was included in yearly cohorts for studies at the clinic or in their homes when there was illness. Smallpox had been eradicated in Guatemala before the study began. Expanded immunization for bacillus Calmette-Guérin (BCG) and diphtheria-pertussis-tetanus (DPT) was nonexistent. These vaccines were often rejected by villagers, but coverage improved through the study period. Vaccines against measles, rubella, and mumps were nor available. The first one-shot national measles immunization campaign was conducted in 1972, the year the Canqué study ended (Mate et al., 1974). More than 95% of children under five developed significant measles antibody titers according to pre and post vaccination representative samples. Measles mortality fell from the precampaign rate of 59 to 4.7 per 100,000 one year after the campaign. Lives were saved by measures of Western medicine. Penicillin was used to treat complicated respiratory infections and other suspected bacterial diseases. Sulfonamides were given for urinary tract infections and other illnesses. Continued breast-feeding was encouraged during attacks of infectious disease and convalescence. Traditional home beverages and intravenous fluid therapy were used to treat dehydrating infectious diseases. Implementation of Western medicine at the clinic was favored by the absence of an Indian shaman at the time of the study. Two pediatricians (Carlos Beteta, 1963-1965; Juan Urrutia, 1965-1974) contributed importantly to the improved health and reduced mortality attained during the study.
Cohorts of Pregnant Women
Pregnant women were the most assiduous in visiting the clinic. Although speaking the local Cakchiquel, they knew sufficient Spanish to communicate with the staff. Vaginal examinations were excluded from the protocol because they were not culturally acceptable. Blood pressure, urinalysis (including bacterial culture and test for pregnancy hormone), and diagnosis for sexually transmitted diseases were carried out. Dietary studies by recall and direct measurement were conducted each trimester.
Examination for intestinal parasites, bacteria, and viruses were performed during pregnancy on most women.
The date of birth was approximated from the date of the last menstruation and uterine height. contact between women, midwives, Ad staff favored identification of impending deliveries. These were assisted by two experienced folk midwives from the village, who collaborated as if they were members of the study team. Auxiliary nurses, posted at the Health Clinic around the clock, observed most of the deliveries during the study period.
Cohorts of Children
The nurses recorded the characteristics of each birth and newborn baby. Babies were examined by the pediatrician soon after birth, and within 1415 hours if born at night. The physician also examined the mothers. All yearly cohorts of children were studied from 1964 through 1972. All the newborns were measured at birth (weight, length, circumference of head and thorax), then daily (weight) for one week, and weekly (weight, length) for one month. Most clinical, dietary, and anthropometric appraisals and collection of laboratory specimens were conducted in the homes. Onset and duration of breast-feeding and weaning were recorded for all. Colostrum and milk were collected from a series of women to determine concentrations of secretory immunoglobulin A (S-IgA) and antibodies to selected pathogenic agents. Hemoglobin and other limited parameters were studied in only a small group of children, because drawing of blood was not readily accepted by villagers. Most newborns appeared healthy and almost all were quite protected from disease during the first weeks of life.
A cohort of 45 children was retrospectively and randomly selected from the children born in the first two years of the study, when the oldest was 18 months of age. Clinical examination and anthropometry were carried out at birth (as above), fortnightly (weight, length, head and thorax circumference) from one month to one year of age, monthly up to age two years, and thereafter at three-month intervals until termination of the study, when the oldest child was nearly eight years old. Weekly dietary investigations by recall were conducted from birth to age three years. All acute and chronic episodes of infectious diseases were recorded for the first three years of life. Fever was measured by thermometer, and anorexia was deduced from the interview with the mother. Illnesses were diagnosed according to standard criteria. This included number of bowel movements per day, duration, recurrence of episodes, and appearance of blood and mucus in stools. Fecal specimens were obtained daily for the first week of life, and weekly thereafter until the end of the third year of life. Stools were brought to the clinic by nurses and relatives within one hour of evacuation. Cultures and other procedures were performed at the clinic's field laboratory.
Cultures taken at the village were processed in the field laboratory, and aliquots were refrigerated or suspended for processing at INCAP's laboratories. Most enteric viruses, bacteria, and parasites known in that epoch were investigated. The indigenous anaerobic and facultative microflora was quantified at weekly intervals, in the field, for 12 randomly selected infants, from birth to age one year. All epidemics of infectious disease in the village were studied.
The rest of the children were examined and measured with the same technique as the 45 cohort, as follows: at birth, weekly for one month, monthly for one year, and at six-month intervals until termination of the study.
Data were recorded in the field in precoded questionnaires and were edited at the clinic and headquarters for computer processing. Approximately 5 million data points were accumulated for analysis.