Survey of indoor cockroaches in some dwellings in Bangkok.

This study aimed to investigate the species distribution of indoor cockroaches in dwellings in Bangkok. Commercial sticky traps were used to catch cockroaches in 128 private residences (40 single houses, 49 townhouses, 39 apartments), 34 offices, and 30 small groceries. The cockroaches were identified as Periplaneta americana, Supella longipalpa, Blattella germanica, Neostylopyga rhombifolia, P. brunnea, P. australasiae, Pycnoscelus surinamensis, and B. lituricallis; two were unidentified species. The most common species were P. americana, S. longipalpa and B. germanica--most of which were nymphal stages. P. americana and S. longipalpa infested all kinds of buildings, especially private residences (50.0% and 17.2%, respectively) and offices (61.8% and 58.8%, respectively); they were also found mostly (15.1%) in mixed infestation and with no predominant species. B. germanica (26.7%) were significantly predominant in groceries. Air conditioners have no influence on cockroach distribution.

A brief survey of free-living amebae in Thailand and Hamamatsu District, Japan.

The aim of this study was to determine the presence of free-living amebae in aquatic habitats of human environments in Thailand and Hamamatsu district, Japan. Genus identification was based on the morphology of cyst and trophozoite forms and a flagellation test for genus Naegleria. The pathogenic potential was tested in mice by nasal instillation for genus Naegleria and Acanthameba. In 14 provinces of Thailand, amebae were isolated in 43 from 95 water samples and 67 from 120 soil swabs. Amebae of 49 isolates from waters were identified as Acanthameba (36.7%), Naegleria (28.6%), Hartmannella (20.4%), Vahlkampfia (12.2%) and Vannella (2%). Soil samples have significantly higher levels of Acanthameba and Hartmannella (p<0.05) but lower for Naegleria (p<0.05) and 7 unidentified amebae were found. In Hamamatsu district, Japan, 62 amebae of the same genera were isolated from 47 of 95 water samples. There were significantly higher levels of Acanthameba (22.6%) (p<0.05) but lower for Naegleria (4.8%) (p<0.05) than those of Thailand which each of them caused death in mice. Three unidentified amebae were isolated. This finding serves as additional evidence for the presence of free-living amebae under natural and the difference in distribution between tropic and subtropic areas.

Angiostrongyliasis: analysis of antigens of Angiostrongylus costaricensis adult worms versus IgG from infected patients with Angiostrongylus cantonensis.

The possibility of cross-reactivity was previously investigated by indirect ELISA with sera from Angiostrongylus cantonensis infections, normal controls and A. costaricensis antigen. 5 microg/ml of crude antigen from both sexes of each species reacted with diluted serum samples (1:800) of each of 20 cases of angiostrongyliasis and normal controls, and further with anti-human IgG conjugate at 1:1,000. The mean absorbance values were evaluated as follows; normal controls showed a value of 0.033 using A. costaricensis antigen lower than (0.085) A. costaricensis antigen. Both mean values of angiostrongyliasis cases were rather close (0.491) using A. costaricensis antigen and the other antigen (0.518). The present study continued with a crude antigen of 13 A. costaricensis females and males. Serum samples were analyzed; 27 sera of angiostrongyliasis, 30 negative controls and 193 cases of other parasitic infections (91 cases of nematodiasis; 45 cases of cestodiasis; 47 cases of trematodiasis and 10 cases of HIV) and 7 cases of other brain infections. This antigen was evaluated for ELISA with a concentration of 5 microg/ml, serum dilution 1:400 and anti-human IgG conjugate at 1:2,000. The test gave sensitivity and specificity at cut-off value 0.261; 92.59% and 73% respectively. The antigen was cross-reactive with 30 cases from 9 out of 10 different kinds of nematodiasis (gnathostomiasis, strongyloidiasis, ascariasis, hookworm infections, trichinosis, toxocariasis, trichuriasis, onchocercosis and Wuchereria bancrofti infections. Five cases from 3 of 6 kinds of cestodiasis (neurocysticercosis, echinococcosis and Hymenolepis nana infections) and 18 cases of 4 out of 5 kinds of trematodiasis (Paragonimus heterotremus infections, opisthorchiasis, schistosomiasis and fascioliasis). One case of other brain infections was observed. The crude antigen of A. costaricensis showed a high percentage sensitivity with serum antibodies of angiostrongyliasis cases. Low specificity of the test was observed by reactions of those serum antibodies with various kinds of antigenic molecules. This study provides baseline data for further immunodiagnosis of human angiostrongyliasis.

A first record from Thailand of human external ophthalmomyiasis due to Oestrus ovis.

A case of external ophthalmomyiasis caused by Oestrus ovis was first reported from Lopburi Province, Central part of Thailand, in January, 1997. A 18-year-old man presented with a several hours history of foreign body sensation in his left eye accompanied by irritation. Eight Oestrus ovis first-instar larvae were removed from lower palpebral conjunctiva. Symptoms and clinical signs resolved in 24 hours after mechanical removal of the larvae. There was no history of contact fly and domestic animals. The larvae were identified by light microscopic examination.

Rapid eradication of trichomonads by single-dosed nimorazole.

Previous in vitro studies demonstrated the rapidity of trichomonacidal action of nimorazole (Naxogin 500) which was twice that of metronidazole and many times that of tinidazole. Since rapid eradication of parasites can lead to a significant decrease in transmission rate, and hence, a lower prevalence of this sexually transmitted disease, a pilot study was designed to investigate the in vivo speed of action of nimorazole. Twenty females with positive wet smears for trichomonas vaginalis were treated with a single 2 gram-dose of nimorazole orally. Without any antiseptics, specimens of vaginal discharge were collected at 0 hour (before treatment), 3, 24 and 72 hours for parasite count and culture. After a single treatment with 2 g of nimorazole the cure rate was 65 per cent at 3 hours and 100 per cent at all points thereafter. The result of this pilot study supports previous in vitro findings that nimorazole rapidly eradicates vaginal parasites.

Detection of antibodies against Opisthorchis viverrini in patients before and after treatment with praziquantel.

Levels of antibody in sera of 78 patients with opisthorchiasis, 30 patients with other liver diseases, 10 patients with schistosomiasis and 30 healthy individuals were compared using three serodiagnostic tests, namely indirect haemagglutination (IHA), enzyme-linked immunosorbent assay (ELISA) and lectin immuno test (LIT). The geometric mean reciprocal titer in sera of opisthorchiasis patients was significantly higher than patients with other diseases, patients with schistosomiasis and healthy individuals (p less than 0.00001). After treatment with praziquantel, the antibody titers were decreased and became lowest 120 days after treatment. A statistically significant decrease from the pre-treatment sample was observed only at 120 days after infection and not earlier and only with ELISA (p = 0.03) and not with IHA and LIT (p greater than 0.05). Even with ELISA, significant decrease in antibody titer was apparent only when the pre-treatment sera had high enough antibody titer. ELISA was therefore better than the other two tests for the assessment of cure provided that the titer of pre-treatment sera was high.

A comparative study of four methods for detecting antibody in asymptomatic giardiasis.

Four immunological methods for diagnosis of giardiasis comprising complement fixation (CF) test, indirect hemagglutination (IHA) test, enzyme-linked immuno sorbent assay (ELISA) and lectin immuno test (LIT) were studied. Fifty sera from asymptomatic giardiasis patients, 40 from patients with other diseases and 50 from healthy controls were evaluated. The seropositive rates in asymptomatic giardiasis were 36% for CF, 58% for LIT, 30% for IHA and 72% for ELISA. The seropositive rates in patients with other diseases were 22.5% for CF, 52.5% for LIT, 12.5% for IHA and 67.5% for ELISA. The results suggest that the test of choice for giardiasis was CF with 88% specificity, nevertheless this test showed low sensitivity (36%). Other two tests, ELISA and LIT were more sensitive than CF with percent sensitivity of 72 and 58 respectively, but these two tests had severe disadvantages in being less specific with percentage specificity of 48 and 60 respectively.