Thailand Expanded Program on Immunization: a ten-years review of coverage and impact on EPI target diseases.

The national immunization coverage in Thailand for all types of vaccine has been steadily increasing since 1978, when the EPI was formally launched. The coverage in 1987 was 96% for BCG, 75% for DPT, 74% for OPV, and 60% for TT. Measles vaccine, which started only in late 1984, had the lowest coverage, 51%, in 1987. During the period 1982-1987, the drop-out rates between the first and third dose of DPT and OPV decreased dramatically from 69% to 13% and from 42% to 13% respectively. Sampling surveys of immunization coverage showed higher coverage for DPT and OPV than those from reporting in all regions, especially in the capital city which has a high concentration of the private health sector. Only the northeastern region had less coverage from surveys than from reporting. Following the launch of EPI, the disease incidence demonstrated a clearly downward trend for diphtheria, poliomyelitis, and measles, while in the case of pertussis and neonatal tetanus, slower of still fluctuating declines were observed. The reported age-specific incidences per 100,000 population in 1986 for children 0-4 years were as follows: 4 for diphtheria, 0.9 for poliomyelities, 180 for measles, 14 for pertussis, and 10 for tetanus.

Measles-associated diarrhoea in northeastern Thailand.

A significant proportion of the illness and death of diarrhoeal diseases in the developing world is estimated to be due to the diarrhoea associated with measles. During February 1983-January 1984 a prospective study of measles in a hospital in Northeastern Thailand was conducted. A total of 550 cases of measles were studied. Diarrhoea was the most frequent complication of measles, occurring in 233 cases (42.4%). The largest proportion (46.2%) of cases with diarrhoea occurred in May-July. Children with measles aged 6-11 months had the highest frequency of diarrhoea (65.7%). Cases aged 1 year and 0-5 months had diarrhoea rates of 60% and 57% respectively. The proportion of measles cases with diarrhoea decreased with increasing age. Only 9.1% (9/99) of stools sent for bacteriological culture were positive. In three of these Shigella spp. were isolated. The rest were non-typhoid Salmonella (2), enteropathogenic Escherichia coli (2), Vibrio cholera (1), and Vibrio parahaemolyticus (1). Other complications among measles cases were pneumonia in 168 (30.5%), otitis media in 28 (5.1%), convulsion in 13 (2.4%), croup in 9 (1.6%), encephalitis in 4 (0.7%), and sepsis in 1 (0.2%). Seven cases (1.3%) died, 4 from pneumonia, 2 from encephalitis, and 1 from sepsis.