MyMedR

Fulltext A preliminary survey of Aedes aegypti in Selangor, Peninsular Malaysia

Ho TM, Vythilingam I

Med J Malaysia, 1980 Jun;34(4):409-14.

PMID: 7219273

A preliminary survey of Aedes aegypti was carried out in 6 areas in the state of Selangor, Malaysia. The densities of Ae. aegypti and Ae. albopictus in the areas were discussed. Results indicated that the distribution of larval habitats varied with the housing type. The most ommon indoor larval habitat in urban areas is the bathroom tank. In both urban and rural areas, outdoor preference is for the earthenware jars. Anttraps have decreased in importance as larvae breeding habitats. The accuracy of house searches can be increased by increasing the number of larvae examined per container to 5 or more. Further study is required to determine whether the findings of this survey is peculiar to the areas surveyed or is representative of the whole country, and whether there is a seasonal fluctuation in the types of preferred larval habitats.

A survey of acarine ectoparasites of bats (Chiroptera) in Malaysia

Ahamad M, Ibrahim H, Bujang MK, Sah SA, Mohamad N, Nor SM, et al.

J Med Entomol, 2013 Jan;50(1):140-6.

PMID: 23427663

A comprehensive 8-yr survey of acarine ectoparasites (ticks and mites) of bats was carried out in 18 localities from 2002 to 2009. Most of the surveys were conducted during 14 national biodiversity scientific expeditions throughout Malaysia. The objective was to identify acarines of known public health importance from bats and thus determine whether there is any potential public health risk in Malaysia. Trapping of bats was conducted using Harp traps and Mist nets. In total, 1,579 individuals comprising of 6 families and 52 species of bats were examined alive. In general, 25.6% of the bats were infested with acarines. Infestation rates of ticks, mesostigmatid mites, and chiggers on bats examined were 0.4, 10.4, and 14.7%, respectively. Their prevalence and mean intensity were tabulated. Genera of ticks extracted were Amblyomma, Dermacentor, Ixodes, and Ornithodoros. Of these genera, only two species can be identified to species level and they are Amblyomma cordiferum and Ixodes simplex. In total, 8 genera and 15 species of mesostigmatid mites were found; the species were Ancystropus eonycteris, Ancystropus zeleborii, Echinonysus nasutus, Laelaps aingworthae, Laelaps nuttalli, Laelaps sanguisugus, Laelaps sculpturatus, Longolaelaps longulus, Longolaelaps whartonii, Meristaspis lateralis, Meristaspis macroglossi, Paraperiglischrus rhinolophinus, Spinturnix acuminatus, Spinturnix americanus, and Spinturnix bakeri. Chiggers on bats were represented by 12 genera and 6 species; the species identified were Gahrliepia fletcheri, Riedlinia lipoxena, Trombigastia cadei, Walchiella impar, Walchiella oudemansi, and Whartonia caobangensis. The study produced an up-to-date list of acarine ectoparasites of bats in Malaysia where a total of 38 genera and 47 species of acarines were listed. Findings of the study demonstrated that 5 genera and 1 species of acarines that may pose potential health risks, can be found on bats.

A survey of ectoparasites in Gunung Stong Forest Reserve, Kelantan, Malaysia

Mariana A, Zuraidawati Z, Ho TM, Mohd Kulaimi B, Saleh I, Shukor MN, et al.

Southeast Asian J. Trop. Med. Public Health, 2005 Sep;36(5):1125-31.

PMID: 16438136

A survey of ticks and other ectoparasites was carried out during a national biodiversity scientific expedition at Gunung Stong Forest Reserve, Kelantan, Malaysia from 23-29 May 2003. A total of 272 animals comprised of 12 species of birds, 21 species of bats, 7 species of rodents and 2 species of insects were examined for ticks and other ectoparasites. From these animals, 5 species in 4 genera of ticks; 7 species in 2 families of Mesostigmatid mites and 5 species of chiggers were collected. Among the ectoparasites found were Ixodes granulatus and Leptotrombidium deliense, which are of known medical importance. A tick island consisting of 10 nymphal stages of Dermacentor spp was observed feeding on Rattus tiomanicus.

A titan in our midst - a tribute to Dato' Dr A. W. E. Moreira

Ho TM

Family Practitioner, 1981;4(2):48-49.

Fulltext Acariasis on pet Burmese python, Python molurus bivittatus in Malaysia

Mariana A, Vellayan S, Halimaton I, Ho TM

Asian Pac J Trop Med, 2011 Mar;4(3):227-8.

PMID: 21771459 DOI: 10.1016/S1995-7645(11)60075-8

OBJECTIVE: To identify the acari present on pet Burmese pythons in Malaysia and to determine whether there is any potential public health risk related to handling of the snakes.

METHODS: Two sub-adult Burmese pythons kept as pets for a period of about 6 to 7 months by different owners, were brought to an exotic animal practice for treatment. On a complete medical examination, some ticks and mites (acari) were detected beneath the dorsal and ventral scales along body length of the snakes. Ticks were directly identified and mites were mounted prior to identification.

RESULTS: A total of 12 ticks represented by 3 males, 2 females and 7 nymphal stages of Rhipicephalus sanguineus (R. sanguineus) were extracted from the first python while the other one was with 25 female Ophionyssus natricis (O. natricis) mesostigmatid mites. Only adult female mites were found. These mites are common ectoparasites of Burmese pythons.

CONCLUSIONS: Both the acarine species found on the Burmese pythons are known vectors of pathogens. This is the first record that R. sanguineus has been reported from a pet Burmese python in Malaysia.

Fulltext Acaricidal activity of Cymbopogon citratus and Azadirachta indica against house dust mites

Hanifah AL, Awang SH, Ho TM, Abidin SZ, Omar MH

Asian Pac J Trop Biomed, 2011 Oct;1(5):365-9.

PMID: 23569794 DOI: 10.1016/S2221-1691(11)60081-6

To examine the acaricidal effects of the essential oil of Cymbopogon citratus leaf extract (lemongrass) and ethanolic Azadirachta indica leaf extract (neem) against house dust mites Dermatophagoides farinae (D. farinae) and Dermatophagoides pteronyssinus (D. pteronyssinus).

Fulltext Acarine ectoparasites of Panti Forest Reserve in Johore, Malaysia

Mariana A, Mohd KB, Halimaton I, Suhaili ZA, Shahrul-Anuar MS, Nor ZM, et al.

Asian Pac J Trop Biomed, 2011 Jan;1(1):1-5.

PMID: 23569714 DOI: 10.1016/S2221-1691(11)60057-9

To identify the presence of acarine ectoparasites and determine whether there is any potential public health risk in Panti Forest Reserve, Johore, Malaysia.

Antibodies to Orientia tsutsugamushi, Rickettsia typhi and spotted fever group rickettsiae among febrile patients in rural areas of Malaysia

Tay ST, Ho TM, Rohani MY, Devi S

Trans R Soc Trop Med Hyg, 2000 9 7;94(3):280-4.

PMID: 10974999

A serosurvey was conducted in 1995-97 among 1596 febrile patients from 8 health centres in Malaysia for antibodies against Orientia tsutsugamushi (OT), Rickettsia typhi (RT) and TT118 spotted fever group rickettsiae (SFGR) by using an indirect immunoperoxidase assay. A total of 51.4% patients had antibody against at least 1 of those rickettsiae. Antibody to SFGR was most prevalent (42.5%), followed by RT (28.1%) and OT (24.9%). The seroprevalences of antibodies to SFGR, RT or OT alone were 12.4, 3.6 and 4.3%, respectively. Antibodies against more than 1 species of rickettsiae were presence in 31.1% of the patients, suggesting the possibility of co-infection, previous exposures or serological cross-reactivities. Seroprevalence of the various rickettsiae varied according to locality, with SFGR antibodies being the most prevalent in most areas. There was no significant association of prevalence of rickettsial antibody with gender. The seroprevalence of OT, SFGR and RT increased with patient age but an increase of antibody titre with age was not significant. Those working in the agricultural sectors had significantly higher seroprevalence of OT, SFGR and RT than those not related with agricultural activities. Scrub typhus remains a public health problem with an estimated annual attack rate of 18.5%. Tick typhus and murine typhus as shown in this serosurvey appear much more widespread than scrub typhus in this country.

Fulltext Antigenic profile of Blomia tropicalis, Aleuroglyphus ovatus and Glycycometus malaysiensis

Tang JC, Wong SF, Mak JW, Ho TM

Trop Biomed, 2011 Aug;28(2):223-36.

PMID: 22041741

House dust mites and storage mites are well-known causes for allergenic diseases. The aim of this study was to investigate the immunogenic sites of Blomia tropicalis, Aleurogyphus ovatus and Glycycometus malaysiensis. The mites were maintained in a culture medium at 25ºC and 75% relative humidity. Mites were harvested either with heat escape or floatation method, purified, homogenized, quantified and used for the production of polyclonal antibody and immunostaining. For each species of mites, five male mice and five male rats were randomly selected and immunized intraperitoneally with respective crude mite extract at two-weekly intervals. Blomia tropicalis, A. ovatus or G. malaysiensis whole mites and paraffin-embedded mite sections were immunostained with the respective polyclonal antibody. The faecal pellets of mites were intensely stained for all the three species in the present study. The legs of sectioned A. ovatus were not immunogenic as compared with those of G. malaysiensis and B. tropicalis. The outer layer (cuticle) of whole mites and the eggs for these species were very immunogenic. Hence, the polyclonal antibodies obtained in this study may serve as potential tools in detecting the eggs and immature mites in environmental samples. Future studies should focus on the antigenic components of eggs since they were relatively abundant in dust and highly antigenic as seen in the present study.

Antigenic types of Orientia tsutsugamushi in Malaysia

Tay ST, Rohani MY, Ho TM, Devi S

Southeast Asian J. Trop. Med. Public Health, 2002 Sep;33(3):557-64.

PMID: 12693591

The seroprevalence of various Orientia tsutsugamushi (OT) strains among Malaysian patients with suspected scrub typhus infections was determined using an indirect immunoperoxidase (IIP) assay. IgG against a single OT strain were detected in six sera (3 Karp, 1 Gilliam and 2 TC586), whereas IgM antibodies against a single OT strain (Gilliam) were noted in 3 sera (Gilliam). IgG reactive to all OT strains were present in 33 (47.1%) of the 70 sera and IgM reactive to all OT strains were present in 22 (78.6%) of the 28 sera. The fact that most sera were reactive to multiple OT strains suggests that group-specific antigens are involved in scrub typhus infections, whereas very few were due to strain-specific epitopes present on these strains. Peak IgG and IgM titers were noted more frequently against Gilliam, Karp, and TA763 strains: this suggests that these strains may be the commonest infecting strains among Malaysian patients. Two predominant OT polypeptides consistently reacted with patients' sera were the 70 kDa and 56 kDa proteins.

Development and evaluation of dot-immunobinding assay for detection of scrub typhus infection in Leptotrombidium fletcheri (Acari: Trombiculidae)

Ho TM, Shara S, Koay AS, Cheong YM

J Med Entomol, 1992 Jul;29(4):611-3.

PMID: 1495069

A dot-immunobinding assay (DIBA) was compared with a direct fluorescent antibody technique (DFAT) for the detection of Rickettsia tsutsugamushi infection in Leptotrombidium fletcheri (Womersley & Heaslip). Laboratory colonies of infected and noninfected chiggers were examined. The relative proportions of positive, negative, and indeterminate results were significantly different between DIBA and DFAT for infected but not for noninfected chiggers. DIBA was more sensitive and had a better negative predictive value and a lower false negative percentage than DFAT. It was concluded that DIBA is a suitable alternative to DFAT for detecting scrub typhus infection in chiggers.

Fulltext Development of ELISA for diagnosis of allergy to Dermatophagoides farinae

Ho TM, Radha K, Shahnaz M, Singaram SP

Med J Malaysia, 1993 Sep;48(3):308-12.

PMID: 8183144

An indirect enzyme linked immunosorbent assay (ELISA) was developed for the diagnosis of allergy to a house dust mite, Dermatophagoides farinae. The efficacy of the ELISA was then evaluated against a prick test using a commercial allergen. Eighty five suspected allergic rhinitis patients from the Otorhinolaryngology Department, Kuala Lumpur General Hospital, were tested with the ELISA and prick test. Prick test and ELISA results were positive in 84.7% and 80.0% of the patients respectively. The ELISA was found to have 87.5% sensitivity, 61.5% specificity, 92.6% positive predictive value, 47.1% negative predictive value, 7.4% false positive and 52.9% false negative. There was total agreement between the prick test and ELISA for prick test grades of 3+ and 4+. It is concluded that the ELISA is a useful assay for detection of individuals who are highly sensitive to D. farinae.

Development of an enzyme-linked immunosorbent assay for detection of IgE antibodies specific to Dermatophagoides pteronyssinus

Ho TM, Yit YH, Husain M

Asian Pac J Allergy Immunol, 1988 Dec;6(2):103-6.

PMID: 3146256

Allergy to Dermatophagoides pteronyssinus was determined in 61 rhinitis patients using prick test (PT), enzyme-immunoassay (EIA) and enzyme-linked immunosorbent assay (ELISA). A total of 43 patients tested positive with PT. Forty six patients were positive when tested with EIA and ELISA. With PT as standard test, EIA was found to have 83.7% sensitivity and 44.4% specificity; ELISA had 81.4% sensitivity and 38.9% specificity. There was a linear relationship between absorbance values obtained by EIA and ELISA. The performance time was 8 hours, 24 hours and 30 minutes for ELISA, EIA and PT respectively. The cost per test for ELISA, EIA and PT was US$ 0.20, US$ 5.20 and US$ 0.14 respectively. It was concluded that ELISA was more cost-effective than EIA should be used to supplement PT for a more complete diagnosis of allergy.

Fulltext Dr Wu Lien-teh: modernising post-1911 China's public health service

Lee KH, Wong DT, Ho TM, Ng KH

Singapore Med J, 2014 Feb;55(2):99-102.

PMID: 24570319

Editorial. Educating oneself

Ho TM

Family Practitioner, 1988;11(3):3-4.

Editorial. KL-Singapore ties: 5 years later

Ho TM

Family Practitioner, 1986;9(1):5-6.

Editorial. Launching an international journal

Ho TM

Family Practitioner, 1983;6(3):5-8.

Editorial: A common destiny

Ho TM

Family Practitioner, 1984;7(2):5-8.

Editorial: Allegory and action

Ho TM

Family Practitioner, 1983;6(2):9-10.

Fulltext Effect of a commercial air ionizer on dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae (Acari: Pyroglyphidae) in the laboratory

Abidin SZ, Ho TM

Asian Pac J Trop Biomed, 2012 Feb;2(2):156-8.

PMID: 23569888 DOI: 10.1016/S2221-1691(11)60212-8

To investigate the short and long term efficacy of a commercial air ionizer in killing Dermatophagoides pteronyssinus (D. pteronyssinus) and Dermatophagoides farinae (D. farinae) mites.

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