Toxocara and Gnathostoma among stray canines in Bangkok.

Stomachs and intestines of 88 adult and 112 young stray dogs were obtained from the Rabies Control Subdivision, Bangkok, and examined especially for the presence of Gnathostoma spinigerum and Toxocara canis. Forty-five dogs were found positive for T. canis (overall prevalence 22.5%) but none were found infected with G. spinigerum. The prevalence of T. canis in young dogs was 37.5% (42 of 112) whereas in adult dogs was only 3.4% (3 of 88). The total number of T. canis recovered from the 45 positive dogs was 272 (averaging 6.0 worms/dog). This includes 268 worms from 42 young dogs (averaging 6.4 worms/dog) and four worms from three adult dogs (averaging 1.3 worms/dog). The average number of worms, according to sex and stage, per young dog were as follows: male worms 2.4 +/- 3.5 (range 0-15), female worms 2.8 +/- 3.5 (0-16), immature worms 1.2 +/- 2.5 (0-9), and all worms 6.4 +/- 8.2 (1-34). The maximum number of worms per young dog was 34 while the minimum was one, and 35.7% (15/42) of these young dogs harbored only one worm. The body length of the recovered T. canis were as follows: males measuring 3.0-12.0 cm (averaging 7.1 +/- 2.1 cm), females 4.1-18.2 cm (11.0 +/- 4.1 cm), and immature worms 0.7-3.7 cm (2.1 +/- 0.8 cm).

The impact of primary health care intervention on reinfection of soil-transmitted helminths in the community.

A study to evaluate the impact of primary healthy (PCH)care practices on the prevention of reinfection of soil-transmitted helminths (STH) was carried out in Nakhon Si Thammarat Province, southern Thailand. Fecal samples from the inhabitants of Ban Paruhas, the implementing village, and Ban Pungsing, the control village, were examined following mass treatment with a three-day regimen of albendazole (400 mg). Training of health volunteers, implementation of a health education program through village broadcasting system and improvements in sanitation including increasing the number of latrines were carried out at Ban Paruhas village. After one year of implementation, prevalence and intensity of STH in both villages were determined using Kato-Katz's method. Pre- and post intervention stool examination results were compared. The overall prevalence of STH at post-intervention decreased significantly in both villages, with a greater degree of reduction appearing in ascariosis and hookworm infections in the village where PHC was implemented.

Effect of albendazole and mebendazole on soil-transmitted helminth eggs.

Primary school children from Nakhon Si Thammarat Province, Thailand, on endemic area of soil-transmitted helminths, were selected for study. The infected children were divided into two groups and pair-matched according to intensity of infections: group I were given albendazole (400mg) single dose and group II were given mebendazole (100mg) twice daily for 3 days. On the day following treatment, the number of Trichuris eggs in the stool markedly increased and the egg shape was also altered. These phenomena did not occur in Ascaris infections since 100% cure rate were obtained using both drugs. Incomplete ovicidal effect of the drugs to Trichuris and Ascaris eggs were demonstrated, embryos were observed to develop within the treated eggs and they hatched after feeding them to experimental animals. In hookworm infection, albendazole stimulated the females to release more eggs after medication, but both drugs showed complete ovicidal effect upon examining the eggs from the second bowel movement.

Minimum effective doses of mebendazole in treatment of soil-transmitted helminths.

Three hundred and fifteen primary school children infected with soil-transmitted helminths were divided into 5 groups. Three groups were treated with 25, 50 and 75 mg mebendazole (MBZ) single dose. One group was given MBZ conventional dose of 100 mg twice daily for 3 days and another group was given albendazole (ABZ) standard dose of 400 mg single dose. Every trial lower MBZ dose 75 mg, 50 mg and 25 mg regimen were highly effective against Ascaris lumbricoides but only moderately effective against Trichuris trichiura and Necator americanus.

Practicable IFAT slide antigen preparations for detection of Gnathostoma spinigerum antibodies in rabbits.

This study was designed to determine which stage of Gnathostoma spinigerum and which method of the preparation of test antigens are the most suitable for the detection of antibodies in serum of rabbits infected with advanced third stage larvae (AL3) of G. spinigerum by the indirect fluorescent antibody test (IFAT). Antigens from parasite ova and first stage larvae (L1) were obtained from freshly preserved specimens and affixed to glass slides with egg albumin. AL3 antigens consisted of paraffin sections, cryostat sections and pellets of crude worm soluble extract. Slides of adult male and female worms were prepared in cryostat sections. Pellets of crude worm soluble extract (AL3) smeared onto slides gave the best positive reaction followed by AL3 cryostat sections and L1.

Comparative study of different doses of mebendazole in hookworm infection.

Sixty six children (40 males, 26 females) aged from 4 to 14 years with hookworm infection were treated with mebendazole. Thirty one and 35 children were treated with mebendazole 300 mg single dose and 600 mg conventional regimen respectively. Stool examination by Kato-Katz technique were done for 3 consecutive days before treatment and on day 14-16, 21-23 after treatment. The cure rate with 300 mg mebendazole was 16.1% with 90.9% egg reduction while 600 mg mebendazole gave 91.4% cure rate with 99.5% egg reduction. No side effects were observed in all children. Four hundred and six adult worms were identified, 99% were Necator Americanus, 0.5% Ancylostoma duodenale and 0.5% Ancylostoma ceylanicum.