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  1. Poon SK, Chew WK
    Folia Parasitol., 1991;38(3):201-7.
    PMID: 1808029
    Faecal samples of 56 common house crows (Corvus splendens Vieillot) were collected from the Petaling Jaya and Kelang districts of Selangor, peninsular Malaysia, and examined for coccidia. Intestinal tracts of 8 of the above crows wee histologically examined under light microscopy to determine the site of coccidial infection and the endogenous stages present. Fifty three (94.6%) crows had coccidial oocysts morphologically conforming to only one species of Isospora in their faeces at the time they were examined. The sporulated oocysts were found to be Isospora corviae (Ray et al. 1952) which has been emended to I. corvi. These oocysts are redescribed in greater detail. Corvus splendens is a new host record for I. corvi. Coccidial infection was observed in all the intestinal tracts and generally confined to the anterior two thirds of the intestine. The parasites occurred within intestinal epithelial cells, located usually above the host cell nucleus. Developmental stages of both the asexual and sexual phases were found in the epithelium, and are deemed to be the endogenous stages of I. corvi on the basis of the oocysts recovered from the same crows used for histological study. These stages are described here for the first time. The prevalence of I. corvi, its relationship with the host C. splendens, and its probable transmission from C. macrorhynchus are discussed.
  2. 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.
  3. 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.
  4. Chew WK, Kurahashi H, Nazni WA, Heo CC, Heah SK, Jeffery J, et al.
    Trop Biomed, 2012 Sep;29(3):489-92.
    PMID: 23018512
    Lispe orientalis Wiedemann, 1824 is recorded for the first time in peninsular Malaysia. Specimens were collected from a mushroom cultivation farm in Genting Highlands, Pahang (3°25'18"N 101°47'48"E). Previously, this species had been recorded from Azerbaijin, India, Russia, Tajikistan, Thailand, Turkey and South Korea. The male of Lispe orientalis can be determined by the following characteristics: body non-metallic, ashy gray, third antennal segment black, R5 cell not narrow apically, hind metatarsus normal, legs entirely black, femora with long bristle-like hairs on av and pv surfaces, hind tibia without av and pv seta and the palpi orangish in colour.
  5. Nazni WA, Jeffery J, Lee HL, Lailatul AM, Chew WK, Heo CC, et al.
    Malays J Pathol, 2011 Jun;33(1):53-6.
    PMID: 21874753 MyJurnal
    A 73-year-old Chinese man was admitted to the Accident and Emergency Premorbid Ward of a local hospital in Malaysia. The patient complained of shortness of breath with cough and was in a semi-conscious state. He was later admitted to an intensive care unit (ICU) of the hospital. Six days after admission 5-6 maggots were recoverd from the nasal cavity. The maggots were identified as the third-instar larvae of Lucilia cuprina Wiedmann (Diptera: Calliphoridae) based on the morphological characteristics. This patient was classified as having nosocomial myiasis. The presence of the third instar larvae indicated that the infestation was not more than three to four days. An adult sarcophagid identified as Parasarcophaga ruficornis (Fabricius) caught in the ICU where the patient was warded provided further evidence of the potential for the nosocomial infestation.
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