Clinical Features, Risk Factors, and Treatments of Microsporidial Epithelial Keratitis.

OBJECTIVE: To report the clinical manifestations, risk factors, and treatments of microsporidial epithelial keratitis in Thailand. METHODS: Twenty eyes of 19 patients were diagnosed and the clinical presentations, risk factors, and management were analyzed. RESULTS: Of 19 patients, six patients (32%) had no apparent risk factors. Predisposing factors included soil exposure (6/19, 32%), water contamination (6/19, 32%), and eye liner (1/19, 4%). Twelve cases (63%) were detected in the rainy season. All cases presented with disseminated, punctated, elevated, epithelial keratitis. Corneal scrapings with Gram-chromotrope staining were positive in all patients. Moxifloxacin 0.5% eye drops were given and all 16 patients experienced complete resolution. Three recurrent cases were resolved with only topical moxifloxacin without corneal scraping or swabbing. CONCLUSIONS: Predisposing factors were not found in some patients; thus, corneal scraping with staining should be considered in cases having a high index of suspicion. The incidence is increased during the rainy season; therefore, clinicians should have more awareness during these times. Debridement with topical moxifloxacin eye drops, without any systemic medication, may be an effective treatment. Corneal scraping or swabbing may not be required in recurrences.

Morphological and molecular identification of a lung fluke, Paragonimus macrorchis (Trematoda, Paragonimidae), found in central Lao PDR and its molecular phylogenetic status in the genus Paragonimus.

Paragonimus macrorchis is rather a rare species with sporadic discovery reports. To date, little is known about morphological features and the molecular phylogenetic status of P. macrorchis. Here we provide such information on P. macrorchis, of which metacercariae were collected from freshwater crabs in Khammouane Province, central Lao PDR. After morphological observation, metacercariae were excysted and were injected intra-peritoneally into Mongolian gerbils. Paragonimus adult worms were collected from the lungs of experimental gerbils 45 days after infection. A small piece of body tissue was cut at the posterior part of each adult worm for genomic DNA extraction. Then, the adult worms were stained and mounted for morphological identification. The second internal transcribed spacer region (ITS2) of rDNA and partial cytochrome c oxidase subunit 1 (cox1) gene were amplified using PCR method and sequenced. The results of morphological identification of metacercariae and adult worms together with their DNA sequences of ITS2 and partial cox1 gene clearly show that the specimens we collected in the central Lao PDR were P. macrorchis. Phylogenetic analyses revealed that P. macrorchis forms an independent cluster from other Paragonimus species in Asia.

Effect of dilution of stool soluble component on growth and development of Strongyloides stercoralis.

Dispersion or dilution of stool by water from heavy rainfall may affect Strongyloides stercoralis free-living development producing infective filariform larvae (FL). This study examined effect of water dilution of stool on survival of S. stercoralis free-living development. One g of stool was prepared in water so that its soluble component was diluted sequentially from 1:2 to 1:480. Three dishes were used to compare FL production in three culture conditions: stool suspension, stool sediment deposited in soil, and isolated rhabditiform larvae (RhL) deposited in soil. The fourth dish was for developmental observation of RhL into free-living stages. Numerous FL were generated from undiluted or 1:2 diluted stool and stool sediment placed on soil. However, starting from dilution 1:5, FL production continuously decreased in both stool suspensions and stool sediments placed on soil. RhL isolated from stool dilutions placed on soil gave rise to few FL. Worm mating were seen at 24-30 hours in dilutions 1:20-1:120 only. Highest numbers of FL from indirect free-living cycle were 1/3 of those from control. FL production decreased as stool dilution increased, and reached zero production at 1:160 dilution. Rainfall may disperse or dilute stool so that nutritional supplement for S. stercoralis free-living development is insufficient.

The Opisthorchis viverrini genome provides insights into life in the bile duct.

Opisthorchiasis is a neglected, tropical disease caused by the carcinogenic Asian liver fluke, Opisthorchis viverrini. This hepatobiliary disease is linked to malignant cancer (cholangiocarcinoma, CCA) and affects millions of people in Asia. No vaccine is available, and only one drug (praziquantel) is used against the parasite. Little is known about O. viverrini biology and the diseases that it causes. Here we characterize the draft genome (634.5 Mb) and transcriptomes of O. viverrini, elucidate how this fluke survives in the hostile environment within the bile duct and show that metabolic pathways in the parasite are highly adapted to a lipid-rich diet from bile and/or cholangiocytes. We also provide additional evidence that O. viverrini and other flukes secrete proteins that directly modulate host cell proliferation. Our molecular resources now underpin profound explorations of opisthorchiasis/CCA and the design of new interventions.

MOLECULAR EVIDENCE OF SPIROMETRA ERINACEIEUROPAEI INFECTION IN SNAKES PTYAS KORROS FROM LAO PDR AND THAILAND AND FROGS HOPLOBATRACHUS RUGULOSUS FROM MYANMAR.

Sparganosis is a parasitic disease in humans and animals caused by plerocercoid larvae (spargana) of the genus Spirometra. Spirometra erinaceieuropaei is the major causative agent of the disease in Asian countries. However, molecular evidence of the causative parasite species in animals remains lacking. A total of 19 spargana specimens were obtained from frogs, Hoplobatrachus rugulosus, collected from Myanmar and snakes, Ptyas korros, from Lao PDR and Thailand. A partial sequence of mitochondrial cytochrome c oxidase subunit1 gene (cox1) was amplified, sequenced, and the phylogenetic relationship was constructed using maximum likelihood method. Results revealed that the level of nucleotide variations in the partial cox1 sequence (429 bp) among the spargana ranged 0-3.5%, with 15 variable sites. Phylogenetic analysis indicated that all spargana specimens were S. erinaceieuropaei. This is the first report of S. erinaceieuropaei in P. korros from Lao PDR and Thailand and H. rugulosus from Myanmar. The results emphasize the need for prevention and control of sparganosis in these regions.

Detrimental effect of water submersion of stools on development of Strongyloides stercoralis.

Strongyloidiasis is prevalent in Thailand, yet its prevalence in the south is lower than in other parts of the country. This might be due to the long rainy season in the south resulting in stool submersion in water inhibiting worm development. In this study, the effect of water submersion of fecal samples on development of Strongyloides stercoralis was investigated. Ten ml of a 1 ∶ 5 fecal suspension were placed in 15-ml tubes, 35-mm dishes, and 90-mm dishes producing the depths of 80 mm, 11 mm and 2 mm-suspensions, respectively. The worm development was followed at 1/6, 4, 6, 8, 10, 12, 14, 16, 24, and 36 h, by determining the number of filariform larva (FL) generated from agar-plate cultures (APC). Fecal suspensions kept in tubes and 35-mm dishes showed a decline in FL yield relative to incubation time and reached zero production 14 h after incubation. In contrast, the number of FL generated from the suspension kept in 90-mm dishes remained stable up to 36 h. Cumulatively, all tubes and 35-mm dishes became negative in APC after 14 h while 90-mm dishes remained APC-positive up to 36 h. Adding more water or stool suspension to dishes resulted in a decreased number of FL. Mechanical aeration of the suspensions in tubes restored an almost normal FL yield. It appears that the atmospheric air plays a significant role in growth and development of S. stercoralis in the environment and may be one of factors which contribute to a lower prevalence of human strongyloidiasis in the south of Thailand.

Albendazole stimulates the excretion of strongyloides stercoralis Larvae in stool specimens and enhances sensitivity for diagnosis of strongyloidiasis.

We succeeded in stimulation of excretion of Strongyloides stercoralis larvae in stool by oral administration of a single dose of 400 mg albendazole to strongyloidiasis patients. This result overcame the false-negative results of stool examination due to low larval numbers. Stool samples were collected from 152 asymptomatic strongyloidiasis patients in the morning, prior to eating. After breakfast, they were given a dose of 400 mg albendazole, and stool samples were collected the following morning. Agar plate culture (APC), modified formalin-ether concentration technique (MFECT), and direct-smear (DS) methods were used to examine stool specimens within 3 h after defecation. The results before and after albendazole was taken were compared. All APCs that were positive became negative after albendazole administration, while MFECT showed a 1.4- to 18.0-fold increase in larval numbers in 97.4% (148/152) of the samples. The DSs were positive in 3 out of 3 smears at a larval number of ≥45 larvae per g (lpg) of stool, and in 1or 2 out of 3 smears at a larval number between 35 and 44 lpg. At a larval number of <35 lpg, the DS became negative. Interestingly 90.5% (19/21) of the samples that were negative by all methods before albendazole administration became positive by MFECT after the treatment. Thus, MFECT can be effectively used for diagnosis of strongyloidiasis with prior administration of albendazole to the subject.

Factors affecting recovery of Strongyloides stercoralis larvae: an approach to a newly modified formalin-ether concentration technique for diagnosis of strongyloidiasis.

To improve the diagnosis efficiency of human strongyloidiasis by using formalin-ether concentration technique (FECT), the effects of various factors on the recovery rates of Strongyloides stercoralis larvae were comparatively evaluated. Fresh stool and a short time exposure of larvae to formalin yielded significantly higher numbers of larvae than preserved stool and 10-min exposure. Likewise, straining through wire mesh yielded a significantly higher number of larvae recovered than straining through gauze did. In addition, centrifugation for 5 min for separation of larvae from debris yielded a significantly greater number of larvae recovered than centrifugation for 2 min did. The efficacies of the five versions of FECT with different factors--FECT 1, FECT 2, FECT 3, FECT 4, and FECT 5--were then compared. It was found that FECT 5 was 1.8, 2.0, 1.9, and 1.4 times more effective than FECT 1, FECT 2, FECT 3, and FECT 4, respectively. FECT 5 is a modified FECT method, whose modifications included using fresh stool without a preservative substance; a short-time rather than 10-min formalin exposure; and the use of wire mesh instead of gauze.