Displaying publications 1 - 20 of 29 in total

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  1. Kavana, N.J., Lim, L.H.S., Ambu, S.
    MyJurnal
    Background: The present study describes the morphology of sparganum (larva) of the Malaysian Spirometra spp. collected from naturally infected frogs (Rana cancrivora) from rice fields in Tanjung Karang, Malaysia.

    Materials and Methods: Spargana of Spirometra spp. collected from naturally infected frogs (Rana cancrivora) were used for the morphological studies. Stretched on a metal ruler, measurements of the worm were recorded. Specimens were stained in Alum-carmine.

    Results: The length of the body ranged from 11-50 mm and the width ranged from 0.5-1.5 mm. Specimens stained with Alum-carmine showed ridges (formation of segments) on the surface of the body, and no sexual organs in the body.

    Conclusion: The Malaysian Spirometra spp. are similar in measurement and morphology to Spirometra erinacei but further studies are required for confirmation.
  2. Inder Singh K, Krishnasamy M, Ambu S, Rasul R, Chong NL
    PMID: 9444010
    Surveillance studies on cercarial dermatitis were carried out in paddy growing areas in Peninsular Malaysia. It was observed that dermatitis in paddy planters occurred in paddy fields which were cultivated using animals such as bafflos or fields where domestic animals were allowed to graze during the off planting season as these animals harbored the parasite. The causative agent of cercarial dermatitis was Schistosoma spindale. A total of 215 small mammals trapped from Alor Setar and 126 trapped from Labu were examined for the schistosome. In Alor Setar Bandicota indica, Rattus argentiventer and Rattus rattus diardii were the only wild mammals found to be infected with the parasite, while in the Labu areas only Rattus tiomanicus jalorensis was positive for the schistosome. The occurrence of S. spindale in R. argentiventer and R.r. diardii in Alor Setar and in R.t. jalorensis in Labu constitute new host and geographic distribution records of the schistosome.
  3. Mastura AB, Ambu S, Hasnah O, Rosli R
    PMID: 9031400
    Frogs caught from two States (Selangor and Langkawi) in Malaysia were examined for spargana of Spirometra sp. Infected frogs usually show no marks of infection but some had swelling and bleeding at the infection site. The size and weight of the infected frogs did not correlate with the infection status. The infection status in relation to human health is discussed.
  4. Ambu S, Mak JW, Ng CS
    J. Helminthol., 1992 Dec;66(4):293-6.
    PMID: 1293196
    The efficacy of ivermectin on experimental infections of P. malaysiensis in rats was determined. Ivermectin was 99.4% and 97.9% effective at a dosage of 400 meg and 800 meg respectively at seven days post-infection. The same two dosages of ivermectin when given at 14 days post infection had an efficacy of 100%. However, as an adulticide it had only 40.7% efficacy. Ivermectin may therefore be useful for the treatment of parastrongyliasis due to the larval stages of the worm which can cause significant pathology in man and animals.
  5. Kavana NJ, Lim L HS, Ambu S
    Trop Biomed, 2014 Sep;31(3):487-95.
    PMID: 25382475 MyJurnal
    The life-cycle of Malaysian Spirometra spp. was studied under experimental conditions in the laboratory. The Cyclops were reared as the first intermediate host, the hamster as the experimental second intermediate host and cat as the definitive host. Maturation and hatching of eggs took 6 to 12 days by incubation at temperature 30 ºC. The hatched coracidium measured 46 x 34 μm. The Cyclops used were susceptible to the coracidial infection. The procercoid older than 5 days in the Cyclop body cavity had minute spines at the anterior end, calcium corpuscles in the body parenchyma and the cercomer at the posterior end. Procercoids 10 to 14 days old were infective to hamster. The plerocercoids from the hamster after 30 days were long and slender and were infective to cats. The plerocercoids experimentally inoculated to cats developed to adult worms and began to produce eggs between 10 to 60 days. Based on the results that have been obtained, a complete life-cycle was successfully elucidated in the laboratory and hamster was identified to be a good laboratory model for a second intermediate host of Spirometra sp.
  6. Krishnasamy M, Singh KI, Ambu S, Ramachandran P
    Folia Parasitol., 1980;27(3):231-5.
    PMID: 7419126
    A helminthological examination of 367 wood rats, Rattus tiomanicus, in an oil-palm. estate 24 miles north of Kuala Lumpur conducted during 1973 revealed 8 species of helminths: 5 nematodes. Angiostrongylus malaysiensis (54.2% of the rats infected), Hepatojarakus malayae (48.5%), Nippostrongylus braziliensis (48.0%), Gongylonema neoplasticum (0.3%), Syphacia muris (17.7%); 3 cestodes, Hymenolepis diminuta (6.0%), Hymenolepis nana (7.6%), Hydatigera taeniaeformis (cysticercus) (12.0%) and 1 pentastomid, Armillifer sp. (nymph) (0.8%). Overall helminthic infection rates seemed to be higher than those previously reported in this host species.
  7. Ambikabothy J, Ibrahim H, Ambu S, Chakravarthi S, Awang K, Vejayan J
    J Ethnopharmacol, 2011 Sep 1;137(1):257-62.
    PMID: 21640180 DOI: 10.1016/j.jep.2011.05.013
    Evaluations of the anti-snake venom efficacy of Mimosa pudica tannin isolate (MPT) obtained from root of the plant.
  8. Chew WK, Wah MJ, Ambu S, Segarra I
    Exp Parasitol, 2012 Jan;130(1):22-5.
    PMID: 22027550 DOI: 10.1016/j.exppara.2011.10.004
    Toxoplasma gondii is an intra-cellular parasite that infects humans through vertical and horizontal transmission. The cysts remain dormant in the brain of infected humans and can reactivate in immunocompromised hosts resulting in acute toxoplasmic encephalitis which may be fatal. We determined the onset and progression of brain cysts generation in a mouse model following acute toxoplasmosis as well as the ability of brain cysts to reactivate in vitro. Male Balb/c mice, (uninfected control group, n = 10) were infected orally (study group, n = 50) with 1000 tachyzoites of T. gondii (ME49 strain) and euthanized at 1, 2, 4, 8 and 16 weeks post infection. Brain tissue was harvested, homogenized, stained and the number of brain cysts counted. Aliquots of brain homogenate with cysts were cultured in vitro with confluent Vero cells and the number of cysts and tachyzoites counted after 1 week. Brain cysts but not tachyzoites were detected at week 2 post infection and reached a plateau by week 4. In vitro Vero cells culture showed similar pattern for cysts and tachyzoites and reactivation of cyst in vitro was not influenced by the age of the brain cysts.
  9. Lord AT, Mohandas K, Somanath S, Ambu S
    PMID: 20307325 DOI: 10.1186/1476-0711-9-11
    The aim of this study was to investigate the presence of multidrug resistant yeasts in the faeces of synanthropic wild birds from the Bangsar suburb of Kuala Lumpur.
  10. Ambu S, Rain AN, Mak JW, Maslah D, Maidah S
    PMID: 9656366
    Three MAbs 1C4.2D8, 1C4.2C4 and 1C4.1F5 were produced using sonicated adult worm antigens of Angiostrongylus malaysiensis and they were found to be secreters of IgG1. The MAbs 1C4.2C4 and 1C4.2D8 were found to react with antigens of A. malaysiensis and cross-react with the closely related A. cantonensis but not with other helminths. A total of 108 human sera collected from Orang Asli (aborigenes) from Grik, in the State of Perak were tested for A. malaysiensis infection using the MAb-ELISA. MAb 1C4.1F5 and 25 (23%) were positive. Twenty of these positive samples were tested with the MAb 1C4.2D8 and none was found to be positive.
  11. Kamis AB, Ahmad RA, Chang JS, Ambu S
    Parasitol Res, 1994;80(1):87-8.
    PMID: 8153134
    Daily intramuscular injection with thyroxine (T4) at a dose of 2.5 micrograms/100 g body weight decreased the larvae and adult worm burden of Parastrongylus malaysiensis in the brain and pulmonary arteries of male Sprague-Dawley albino rats. In contrast, rats treated with propyl thiouracil (PTU), an antithyroid drug, at a dose of 3.75 mg/100 g body weight retained greater numbers of larvae and adult worms. The results may reflect the contrasting immunomodulatory effects of T4 and PTU that influence the susceptibility of the host.
  12. Mak JW, Navaratnam V, Grewel JS, Mansor SM, Ambu S
    Am J Trop Med Hyg, 1993 Apr;48(4):591-6.
    PMID: 8480868
    A clinical trial on the efficacy of a single oral dose of ivermectin at 20, 50, 100, and 200 micrograms/kg was carried out in 40 subjects with subperiodic Brugia malayi microfilaremia. There was no significant difference in the clearance of microfilaremia in the four treatment groups, and the lowest geometric mean microfilarial count (GMC) achieved in the 40 subjects was 8.8/ml or 8.3% of the initial count (106.1/ml), at two weeks post-treatment. The GMC started to increase at one month post-treatment and by six months was 22.2% of the initial GMC. Only 27.5%, 23.1%, 15.0%, and 18.9% of subjects were amicrofilaremic at two, four, 12, and 24 weeks post-treatment, respectively. Mild fever in 35% of the subjects was the primary side reaction and was more common in those with microfilarial counts > or = 500/ml (85.7%) than in those with counts < 500/ml (32%). The clearance of B. malayi microfilaremia by ivermectin was less rapid than that reported for Wuchereria bancrofti. The smaller number of side reactions encountered in the present study compared with those reported for bancroftian filariasis is probably related to the lower microfilarial density in the present subjects. Since ivermectin at a single oral dose of 20-200 micrograms/kg can reduce the GMC to less than 10% at two weeks and maintain it below 25% of the initial level even at six months post-treatment, it is recommended that the drug be seriously evaluated for use in the control of brugian filariasis.
  13. Chew WK, Segarra I, Ambu S, Mak JW
    Antimicrob Agents Chemother, 2012 Apr;56(4):1762-8.
    PMID: 22271863 DOI: 10.1128/AAC.05183-11
    Toxoplasma gondii is a parasite that generates latent cysts in the brain; reactivation of these cysts may lead to fatal toxoplasmic encephalitis, for which treatment remains unsuccessful. We assessed spiramycin pharmacokinetics coadministered with metronidazole, the eradication of brain cysts and the in vitro reactivation. Male BALB/c mice were fed 1,000 tachyzoites orally to develop chronic toxoplasmosis. Four weeks later, infected mice underwent different treatments: (i) infected untreated mice (n = 9), which received vehicle only; (ii) a spiramycin-only group (n = 9), 400 mg/kg daily for 7 days; (iii) a metronidazole-only group (n = 9), 500 mg/kg daily for 7 days; and (iv) a combination group (n = 9), which received both spiramycin (400 mg/kg) and metronidazole (500 mg/kg) daily for 7 days. An uninfected control group (n = 10) was administered vehicle only. After treatment, the brain cysts were counted, brain homogenates were cultured in confluent Vero cells, and cysts and tachyzoites were counted after 1 week. Separately, pharmacokinetic profiles (plasma and brain) were assessed after a single dose of spiramycin (400 mg/kg), metronidazole (500 mg/kg), or both. Metronidazole treatment increased the brain spiramycin area under the concentration-time curve from 0 h to ∞ (AUC(0-∞)) by 67% without affecting its plasma disposition. Metronidazole plasma and brain AUC(0-∞) values were reduced 9 and 62%, respectively, after spiramycin coadministration. Enhanced spiramycin brain exposure after coadministration reduced brain cysts 15-fold (79 ± 23 for the combination treatment versus 1,198 ± 153 for the untreated control group [P < 0.05]) and 10-fold versus the spiramycin-only group (768 ± 125). Metronidazole alone showed no effect (1,028 ± 149). Tachyzoites were absent in the brain. Spiramycin reduced in vitro reactivation. Metronidazole increased spiramycin brain penetration, causing a significant reduction of T. gondii brain cysts, with potential clinical translatability for chronic toxoplasmosis treatment.
  14. Ooi SS, Mak JW, Chen DK, Ambu S
    Ind Health, 2017 Feb 07;55(1):35-45.
    PMID: 27476379 DOI: 10.2486/indhealth.2015-0218
    The free-living protozoan Acanthamoeba is an opportunistic pathogen that is ubiquitous in our environment. However, its role in affecting indoor air quality and ill-health of indoor occupants is relatively unknown. The present study investigated the presence of Acanthamoeba from the ventilation system and its correlation with other indoor air quality parameters, used in the industry code of practice and its potential as an indicator for indoor air quality. Indoor air quality assessments were carried out in nine commercial buildings with approval from the building management, and the parameters assessed were as recommended by the Department of Occupational Safety and Health. The presence of Acanthamoeba was determined through dust swabs from the ventilation system and indoor furniture. Logistic regression was performed to study the correlation between assessed parameters and occupants' complaints. A total of 107 sampling points were assessed and 40.2% of the supplying air diffuser and blowing fan and 15% of the furniture were positive for cysts. There was a significant correlation between Acanthamoeba detected from the ventilation system with ambient total fungus count (r=0.327; p=0.01) and respirable particulates (r=0.276; p=0.01). Occupants' sick building syndrome experience also correlated with the presence of Acanthamoeba in the ventilation system (r=0.361; p=0.01) and those detected on the furniture (r=0.290; p=0.01). Logistic regression showed that there was a five-fold probability of sick building syndrome among occupants when Acanthamoeba was detected in the ventilation system.
  15. Chan LL, Mak JW, Ambu S, Chong PY
    PLoS One, 2018;13(10):e0204732.
    PMID: 30356282 DOI: 10.1371/journal.pone.0204732
    The detection and identification of two endocytobiotic bacterial strains, one affiliated to the "Candidatus Caedibacter acanthamoebae"/"Ca. Paracaedimonas acanthamoeba", and another to the endosymbiont of Acanthamoeba UWC8 and "Ca. Jidaibacter acanthamoeba" are described. For endocytobiont screening, we developed a PCR method with a set of broad-range bacterial 16S rRNA primers to substitute the commonly used but technically demanding fluorescent in situ hybridization technique. Our PCR test alone without sequencing failed to discriminate the endocytobiont-containing and endocytobiont-free Acanthamoeba sp. due to the presence of mismatched primers to host mitochondrial DNA. We highlighted the need to perform bacterial primer checking against the Acanthamoeba genome to avoid false positive detection in PCR. Although the genetic aspect of "Ca. Caedibacter acanthamoebae"/"Ca. Paracaedimonas acanthamoeba" and the endosymbiont of Acanthamoeba UWC8/"Ca. Jidaibacter acanthamoeba" are well studied, knowledge pertaining to their morphologies are quite vague. Hence, we used transmission electron microscopy to examine our endocytobionts which are affiliated to previously described intracellular bacteria of Acanthamoeba sp. We used good-quality TEM images for the localization and the fate of the current endocytobionts inside different life stages of the hosts. Furthermore, to the best of our knowledge, our TEM findings are the first to provide morphological evidence for the clearance of defective Acanthamoeba endocytobionts via an autophagic-like process.
  16. Quah JX, Ambu S, Lim YA, Mahdy MA, Mak JW
    Parasitology, 2011 Apr;138(5):573-7.
    PMID: 21232175 DOI: 10.1017/S0031182010001691
    Cryptosporidium species are protozoan parasites that infect humans and a wide variety of animals. This study was aimed at identifying Cryptosporidium species and genotypes isolated from avian hosts. A total of 90 samples from 37 different species of birds were collected throughout a 3-month period from April 2008 to June 2008 in the National Zoo of Kuala Lumpur, Malaysia. Prior to molecular characterization, all samples were screened for Cryptosporidium using a modified Ziehl-Neelsen staining technique. Subsequently samples were analysed with nested-PCR targeting the partial SSU rRNA gene. Amplicons were sequenced in both directions and used for phylogenetic analysis using Neighbour-Joining and Maximum Parsimony methods. Although 9 (10%) samples were positive for Cryptosporidium via microscopy, 8 (8.9%) produced amplicons using nested PCR. Phylogenetic trees identified all the isolates as Cryptosporidium parvum. Although C. parvum has not been reported to cause infection in birds, and the role of birds in this study was postulated mainly as mechanical transporters, these present findings highlight the significant public health risk posed by birds that harbour the zoonotic species of Cryptosporidium.
  17. Lim PK, Yamasaki H, Mak JW, Wong SF, Chong CW, Yap IK, et al.
    Acta Trop, 2015 Aug;148:32-7.
    PMID: 25910623 DOI: 10.1016/j.actatropica.2015.04.011
    Human toxocariasis which is caused mainly by the larvae of Toxocara canis and Toxocara cati, is a worldwide zoonotic disease that can be a potentially serious human infection. The enzyme-linked immunosorbent assay (ELISA) using T. canis excretory-secretory (TES) antigens harvested from T. canis larvae is currently the serological test for confirming toxocariasis. An alternative to producing large amounts of Toxocara TES and improved diagnosis for toxocariasis is through the development of highly specific recombinant antigens such as the T. canis second stage larva excretory-secretory 30 kDa protein (recTES-30). The aim of this study was to evaluate the sensitivity and specificity of a rapid diagnostic kit (RDT, named as iToxocara kit) in comparison to recTES-30 ELISA in Serendah Orang Asli village in Selangor, Malaysia. A total of 133 subjects were included in the study. The overall prevalence rates by ELISA and RDT were 29.3% and 33.1%, respectively, with more positive cases detected in males than females. However, no association was found between toxocariasis and gender or age. The percentage sensitivity, specificity, positive predictive value and negative predictive value of RDT were 85.7%, 90.1%, 80% and 93.2%, respectively. The prevalence for toxocariasis in this population using both ELISA and RDT was 27.1% (36/133) and the K-concordance test suggested good agreement of the two tests with a Cohen's kappa of 0.722, P<0.01. In addition, the followed-up Spearman rank correlation showed a moderately high correlation at R=0.704 and P<0.01. In conclusion, the RDT kit was faster and easier to use than an ELISA and is useful for the laboratory diagnosis of hospitalized cases of toxocariasis.
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