||Chapman JS & Dyerly MD
||Social and other factors in intrafamilial transmission
||AME REV RESPIR DIS 1964, 90, 48-59.
A prospective study of infection with TB among
680 contacts of 187 families in which there was at least one adult
with active TB was carried out by the Dept. of Internal Medicine
and Medical School of Texas. The family unit was defined as the
one which occupied the same domicile (nuclear and extended). Three
distinct groups: 1) Spanish-speaking Americans (SSA), 2) English-speaking
whites (ESW), and, 3) English-speaking Negroes (ESN) appeared in
the study population. The six characteristics chosen for study were,
intimacy with source, severity of disease, age of contact, income,
crowding and mode of living. The first three factors were independent
of social factors. The analysis was done by scoring method. The
findings of the study revealed a gross rate of 47% infection. A
wide range of tubercular infection existed; 26.7%, 17.6% and 11.9%
of all the contacts of the families of ESW, ESN and SSA were infected
respectively. Similarly, no contacts of 27% of the families were
infected. Infection in less than 6 years of age was nearly the same.
For the three population groups, the rate of infection of 53% was
highest among the SSW and lowest among the ESN, with a rate of 42.5%.
It was found that the ESW had the stronger family structure and
ESN the most unstable structure. The social factors of overcrowding
and an impoverished mode of living has an important effect. Rates
of infection are about 2-3 times higher when sputum is infectious
and is positive on microscopy examination. The non-radiological
factor being associated with higher infection rate is the outstanding
feature of all studies and findings of this study are consistent
with the other studies. Social characteristics seem to operate only
as they contribute to the environmental factor in the transmission
of tubercular infection
|.KEYWORDS: SOCIO-ECONOMICS; SOCIAL ASPECTS; USA.