Progress and achievement of rabies control in Thailand.

The breakthrough in production of highly efficacious human and animal rabies vaccines has led to successful rabies control in developed countries, but rabies is still a major health problem in many developing countries. In Thailand, the new cell culture vaccines-purified chick embryo cell (PCEC), purified Vero cell (PVRV), purified duck embryo (PDEV) and human diploid cell (HDCV) are available, and since 1993 have completely replaced the nervous tissue vaccines. The impact of these cell culture vaccines has been considerable, with the number of human rabies deaths decreasing from 200-300 in the early 1980s to 74 in 1995. Rabies prevention has also focused on the vaccination of dogs, and since 1992, the year the Rabies Prevention Act was announced, every owned dog has to be vaccinated at 2-4 months of age annually thereafter. However, only about 20% of dogs have been vaccinated. In 1995, the Ministry of Agriculture and Cooperation collaborated with the Ministry of Public Health to set up a target of no human rabies deaths in 1996, and a rabies-free Thailand by the year 2000. An extensive educational campaign is underway.

A simplified and economical intradermal regimen of purified chick embryo cell rabies vaccine for postexposure prophylaxis.

Healthy volunteers were randomized to receive either intradermal purified chick embryo cell rabies vaccine (PCEC) alone (0.1 ml at each of two sites on days 0, 3 and 7, and at one site on days 28 and 90) (n = 81), or intradermal PCEC with one dose of human rabies immunoglobulin (HRIG) intramuscularly at 20 IU kg-1 on day 0 (n = 52). Neutralizing antibody (NAB) was detectable in every volunteer, in both groups, from day 14 up to day 365. The peak NAB occurred on day 28 in both groups. No significant suppressive effects of HRIG on NAB response were observed. Side-effects were mild and self-limiting. These preliminary results suggest that this simplified low-dose intradermal regimen could be an alternative schedule in rabies postexposure prophylaxis, resulting in lower overall costs.

The abbreviated 2-1-1 schedule of purified chick embryo cell rabies vaccination for rabies postexposure treatment.

During August 1988 to January 1990, the immunogenicity and safety of purified chick embryo cell rabies vaccine (PCEC) given by the conventional and abbreviated regimens in 82 vaccinees moderately to severely exposed to laboratory proven rabid animals were studied. The 16 vaccinees received PCEC six doses as conventional schedule on days 0, 3, 7, 14, 28 and 90, the 11 vaccinees received six doses of PCEC plus human rabies immune globulin (HRIG) on day 0. The 29 vaccinees received an abbreviated schedule of PCEC as two doses on day 0, one dose each on days 7 and 21 and the 26 cases received PCEC abbreviated schedule plus HRIG on day 0. The kinetics of the neutralizing antibodies on days 0, 7, 14, 28, 56, 180 and 365 were studied for comparative purpose. All vaccinees had high antibody levels from day 14 which last longer than a year and were safe after one year follow up. The adverse reactions of the vaccine were mild and self-limited.

Follow-up of protective antibody level after post-exposure vaccination with purified tissue culture rabies vaccine (PCEC) small doses intradermally.

Twenty-nine vaccinees, 18 males, 11 females, aged 2-61 years (median 12 years) received PCEC intradermally for post-exposure prophylaxis during February to May 1989. Twenty-one cases received 4 sites of 0.1 ml ID on days 0, 3, 7 and 1 site ID on days 28 and 90. Four cases received 4 sites ID on days 0, 3, 7 and 1 site on days 14 and 28. The other 4 cases got the different schedules of ID by the poor compliance. Blood specimens were taken from these vaccinees at 2, 6 or 7, 9, 12 and 16 months after the initial dose. Neutralizing antibodies were measured by standard mouse neutralization test used WHO rabies antiserum as reference. All 65 tested sera showed positive neutralizing antibody. The GMT of antibodies at months 2, 6 or 7, 9, 12 and 16 were 17.68, 2.01, 1.56, 0.88 and 0.56 IU/ml respectively. Mild itching at injection sites was reported in 3 cases and low fever with malaise in 1 case.

Pre-exposure vaccination with purified chick embryo cell rabies vaccines in children.

Children who have close contact with rabid dogs, with a history of neither being bitten nor scratched nor licked on broken skin or on mucous membranes were given purified chick embryo rabies vaccine as pre-exposure prophylaxis. Thirteen children received 0.5 ml of the vaccine, while 12 children received 1 ml of the vaccine intramuscularly on days 0, 7 and 28. The rabies antibody level was measured by a standard mouse neutralization test. Before vaccination, all vaccinees had no detectable level of antibody to rabies. On day 14, all children had antibody levels higher than 0.5 IU/ml; the titer peaked from day 28 to day 56 and then was lower on day 90. Children of the 1 ml group had antibody levels higher than the 0.5 ml group, but there was no statistically significant difference. No serious reaction occurred. At 2-3 years of follow up, all children were doing well.

Rabies and post-exposure prophylaxis in Thai children.

Thailand is an endemic area for rabies, with approximately 300 human deaths reported annually. More than half of the rabies patients are children under 14 years of age. This paper reports clinical data of paediatric rabies cases occurring from 1980 to 1986, and the protective efficacies of human diploid cell rabies vaccine (HDCV) and purified Vero cell rabies vaccine (PVRV) in children exposed to rabid animals. The analysis of 120 medical records revealed that rabies in children had incubation periods which ranged from less than fifteen days to more than three months, but generally between one to three months. The most frequent symptoms observed in the patients were hydrophobia, restlessness, fever, vomiting and aerophobia. Most of the rabid children admitted to hospital died within 24 hours. HDCV was administered to 50 children exposed to rabies with the cumulative dosages of 327 ml. All patients survived without serious adverse effects during a-two year follow-up. Mild reactions were seen in 1.5 percent (5/327 doses). Unfortunately, levels of rabies antibody in these vaccinees were not determined. Among another series of children exposed to rabid animals, comprising 27 individuals who received a total of 168 doses of PVRV, only mild local reactions were seen in 6 subjects. No rabies deaths were reported in 2 years of follow-up. The children who received PVRV either with or without human rabies immune globulin developed similar levels of rabies neutralizing (NT) antibody, which reached the high titers on day 30. At one year after the first dose of vaccination, all vaccinees still had NT antibody at titers higher than 0.5 IU/ml.(ABSTRACT TRUNCATED AT 250 WORDS)