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.

The Thai expanded programme on immunization: role of immunization sessions and their cost-effectiveness.

A cost-effectiveness study of the Thai expanded programme on immunization was carried out in district hospitals and health centres in Thailand during early 1987. The total annual spending on immunization was US $3852 in hospitals and US $813 in health centres. The percentage distribution of annual costs was similar in both facilities. Salaries were the largest component, followed by building and vaccine costs. The frequency of immunization sessions was the most important factor in determining total costs--immunization costs increasing with the frequency of sessions. In hospitals the average number of fully immunized children was 184, compared with 49 in health centres. The cost per fully immunized child varied widely from US $5.30 to US $33.20, and the most cost-effective facilities were those that immunized the greatest number of children. With the present number of health facilities in all areas of the country, which correspond to saturation levels, the most likely way for the Thai programme to reduce costs would be to make better use of staff time by decreasing the frequency of the services offered, thereby increasing the efficiency of each session. Hospitals should adjust the frequency of their immunization sessions according to the number of children being served, but health centres should offer sessions only monthly or once every two months.

PIP: A cost-effectiveness study of the extended immunization program in Thailand surveyed data from 4 provinces for the fiscal year of 1986. The study's objective was to better use scarce health resources especially in difficult economic times. The survey assessed the total annual spending for hospitals and health centers in U.S. dollars: $3,582 in hospitals and $813 in health centers. In relation to the number of 1 year old children in their respective area, hospitals showed 100% coverage of immunization and not more than that. The vaccine was administered in predetermined clinics that also continued with supplementary outreach activities. The immunization costs for each child was $13.80 in hospitals and $11.80 in health centers and $8.90 and $10.30, respectively for pregnant women. Higher administrative and construction expenses caused hospitals to have higher immunization costs than health centers. Salary was identified as the major factor in both operating and total costs. The output and coverage in hospitals was better than that of centers. Higher hospital costs could be justified by the frequency of immunization and the service load. The hospital immunization sessions should be organized according to service load with the frequency increasing with the number of children. Potential factors such as a decrease in birth rate and the change-over of users to local care should be considered in future studies of immunization coverage and effective health facility use.

Public health aspects of opisthorchiasis in Thailand.

Opisthorchiasis is one of the diseases of public health importance in Thailand. It has been estimated that approximately 7 million of the population harbour this liver fluke. Although the mortality rate is not high, the morbidity causes increased loss of man power (work days lost) and economic problems to the people. The infection is common among the rural population of Northeast Thailand, which has increased from 3.5 million in 1965 to 5.4 million in 1981. This high prevalence is due to the population explosion and adverse effects of development of reservoirs and large scale irrigation systems in the area, thereby increasing the fisheries of intermediate hosts. The increased prevalence is also attributed to lack of proper sanitation facilities and people's customary habit of eating raw fish. In spite of control measures to reduce the prevalence rate through improved sanitation and health education, success could not be achieved. It is, however, hoped that through extended primary health care, intensified health education and mass treatment with the drug of choice, the campaign to control opisthorchiasis will finally meet with success.

A pilot project for controlling O. viverrini infection in Nong Wai, Northeast Thailand, by applying praziquantel and other measures.

In a pilot control project of Opisthorchis viverrini in the village of Nong Wai Irrigation Area, Khon Kaen, Northeast Thailand, selected population based chemotherapy with a single dose of 40 mg/kg of praziquantel (2 - cyclohexylcarbonyl-1,2,3,6,7,11 b-hexahydro-4H-pyrazino [2,1-a]isoquinolin-4-one,EMBAY8440,Biltricide) was given to the stool positive cases once a year for a period of 3 years commencing May 1981. Two villages (pop 942) with a prevalence of 58.3% were used as tests villages and another one (pop. 442) with a prevalence of 55.1% served as control. The project programme integrated chemotherapy, sanitation improvement and health education, whilst only chemotherapy was applied in the control village. Among the 736 cases of all villages, 666 were treated in the first year and the parasitological cure rate after one month was 95.9%. Side effects of praziquantel were minor and were minimized by changing the time of drug intake from morning to after dinner. After one year the prevalence of opisthorchiasis was 36.8% in the test villages and 54.8% in the control village. The study on re-infection rate revealed that the average monthly incidence rate among the population in the test villages was 2.0% per month (range 1.1-5.0%) whereas it was 5.0% per month (range 1.9-10.3%) in the control village. In May 1982, second treatment was given again to the positive cases in the three villages with the same dose. The second year evaluation is in progress.

Mass treatment of opisthorchiasis in Northeast Thailand.

In an attempt to control opisthorchiasis, a single dose of 40 mg/kg of Praziquantel was given to 666 people in the three villages of Nam Pong Water Resource Development Project, Khon Kaen, Northeast Thailand. The results showed a cure rate after 1 month was 95.9%. The side effect was minimized by alternation of the time of treatment from after breakfast to after dinner. The use of Praziquantel for the mass treatment in control of opisthorchiasis is possible. However, to achieve the objective of control programme other measures such as environmental sanitation improvement, health education and change in eating habits must be integrated into the programme.