Genomic-based discovery and validation of novel anti-filarial drugs.

Background: Lymphatic filariasis is a mosquito-transmitted disease, while onchocerciasis is transmitted by blackflies. There is no vaccine for these infections. New drugs are required for improvement of current therapies. Objective: This article reviews recent advances in filarial parasite genomics and opportunities for new antifilarial drug research. Methods and results: Genomic approach to filarial parasites provides new prospects for target validation. Comparative genomics filters enable us to select filarial parasite-specific gene products of interest. Functional genomics filters allow the selection of gene products essential for pathogen survival. The validated targets could be prioritized and categorized by informatics methods and manual curation. Conclusion: Lymphatic filariasis and onchocerciasis can be eliminated by either sterilizing or killing adult worms. It is most advantageous to target Wolbachia species for developing new drugs. Functional genomic approaches using microarrays, proteomics, and model organisms, have significantly expanded options for researchers. The genomic-based approach is promising for anti-filarial drug discovery in the future.

Prevalence of intestinal parasitic infections among school children in the central region of Thailand.

OBJECTIVE: Survey the prevalence of intestinal parasitic infections in 14 primary schools of Central Thailand. MATERIAL AND METHOD: A cross sectional survey of the prevalence of intestinal parasitic infections in 14 primary schools of Central Thailand that included Ang Thong, Ayudthaya, and Suphanburi provinces was conducted One thousand and thirty seven children with age ranging from 3-12 years (540 males and 497 females) were examined for intestinal parasites by the formalin-ether concentration technique. RESULT: The overall prevalence was 4.24%. The pathogenic parasites found were Giardia lamblia (1.25%), Enterobius vermicularis (0.19%), Trichuris trichiura and Hookworm (0.19% each), respectively. The common non-pathogenic protozoa found were Entamoeba coli (1.64%) and Endolimax nana (0.48%). The infection rate of Blastocystis hominis was 0.19%. CONCLUSION: Interestingly, the area studied which is low and flat and contains rice and water chestnut fields and small rivers, did not demonstrate Fasciolopsis buski as highly found in the past five decades. However, Parasittic infections are still public health problems in Thailand Close monitoring and control of parasitic infections is needed

Decrease of mosquito salivary gland proteins after a blood meal: an implication for pathogenesis of mosquito bite allergy.

Salivary gland protein profiles ofAedes aegypti (L.) and Culex quinquefasciatus (Say) pre- and post-blood feeding were analyzed. SDS-PAGE studies before blood feeding of Ae. aegypti demonstrated 8 major polypeptide bands of 20, 35, 37, 42, 45, 47, 70 kDa and a high molecular weight band >118 kDa, whereas those of Cx. quinquefasciatus demonstrated 9 major polypeptide bands of 20, 26, 36, 38, 45, 47, 49 kDa and 2 high molecular weight bands >118 kDa. After a blood feeding, salivary gland polypeptides of Ae. aegypti at 35, 37, 45, 47, 70 kDa and high molecular weight band >118 kDa were depleted, while the polypeptide bands of 20, 26, 36, 38 kDa were depleted in Cx. quinquefasciatus. The presented study suggests that these major polypeptides were introduced into vertebrate hosts when a mosquito took a blood meal. Further investigation in molecular, biochemical and immunological aspects of these salivary gland polypeptides may provide information for better understanding in the role of these proteins in mosquito bite allergy.

Resolution of eosinophilia after treatment of cutaneous gnathostomiasis.

The present study was to investigate the dynamics of eosinophil in peripheral blood of patients with cutaneous gnathostomiasis before and after worm removal. The total of 28 proven cases of cutaneous gnathostomiasis treated by albendazole were included in the present study. The absolute eosinophil count (AEC) was higher than 500/ul during infestation in almost all the patients, the positive rate was 89%, and significantly decreased to normal level after receiving albendazole and worm removal within 3 months in 96%. In conclusion, an increas of AEC is another important hallmarks of cutaneous gnathostomiasis and this parameter could be the earlier indicator for responsiveness to treatment.

Pneumocystis jiroveci in HIV/AIDS patients: detection by FTA filter paper together with PCR in noninvasive induced sputum specimens.

OBJECTIVES: To detect P. jiroveci (previously named P. carinii) by PCR using FTA filter paper to extract the DNA, from noninvasive induced sputum samples of HIV/AIDS patients. MATERIAL AND METHOD: Fifty two HIV/AIDS patients suspected of Pneumocystis jiroveci pneumonia (PJP) in King Chulalongkorn Memorial Hospital were recruited. Both cytological method and PCR with FTA filter paper technique were performed to detect P jiroveci from each specimen. RESULTS: The detectability rate of P. jiroveci infection was 21%. The PCR with FTA filter paper method was 4 folds much more sensitive than Giemsa staining technique. P. jiroveci was detected in 18% of the HIV/AIDS patients in spite of receiving standard PJP prophylaxis. CONCLUSION: Detection of P. jiroveci by using FTA filter paper together with PCR in induced sputum samples could detect more cases of P. jiroveci infection than by using cytological method. DNA extraction using the FTA filter paper was more rapid and convenient than other extraction methods. The causes of failure of PJP prophylaxis should be evaluated.

Computer-assisted instruction in parasitology: a cross-over design.

We report here the results of the study using CAI compared to the hard copy for study of lessons in parasitology. We evaluated the CAI compared to hard copy lessons in 60 students, attending the third-year parasitology course at Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. The students were randomly divided into two groups (30 each). The lessons tested were Ascaris lumbricoides and Enterobius vermicularis, which were prepared as CAI and hard copy form. Using a cross-over design, the first group was provided CAI form on the topic of A. lumbricoides, then switched to hard copy form on the topic of E. vermicularis. The second group was provided hard copy form on the topic of A. lumbricoides, then switched to CAI form on the topic of E. vermicularis. After 30 minute reading, the 10-multiple choice question test was provided for each topic. There was no significant difference of the scores between 2 groups. The most students (91.67%) had more satisfaction when using CAI compared to hard copy in terms of easy to use, convenient to use, less time consuming, more understandable, more attractive to read, and less stress for study. There were 32.8% students complaining that reading hard copy was boring. Other comments were stress when reading (2%), more difficult (17.2%) and more time needed to search specific information (17.2%), and wasting papers (17.2%). However 58.6% still complained problems when using CAL. About 25% had physical discomfort (e.g. Headache, eye pain), and 25% had difficulty to access to use CAI (e.g. no computers available, problems with computer or network error). We suggested that instructors should create and improve CAI lessons in biomedical sciences both in quantity and quality (e.g. content with details, pictures, narrations).

Annual laboratory checkup: early signs of health problems in young and middle-age adults.

The objective of this descriptive study was to review the usefulness and relevance of the present parameters provided in an annual laboratory health checkup program. Three hundred sixty-four volunteers were randomly selected, composed of 141 males and 223 females age 15 to 81 years old. Samples from all the volunteers were analyzed for CBC, FBG, BUN, Cr, uric acid, Chol, HDLc, Tg, AST, ALT, ALP, UA and stool examination. More than half the young adults (67.7%, 63 of 93) had abnormal laboratory results. This was higher than in the middle-age group (56.8%, 154 of 271).

Prevalence of parasitism among students of the Karen hill-tribe in Mae Chame district, Chiang Mai province, Thailand.

Infection caused by intestinal parasites is still a common health problem in a poor-hygiene population especially for children in developing countries. A cross-sectional study was conducted among 781 Karen students (age: 3 to 19, males: 325, females: 456) to determine the current status of intestinal parasitic infections in a mountainous area in the North of Thailand. The study was drawn from three schools in the Doi Inthanon region, in Mae Chame district of Chiang Mai province, from December 2002 to June 2003. The techniques used for the diagnosis were: stool concentration by using the 'formalin-ether' technique and perianal region examination by using the 'Scotch-tape' technique. The average rate of intestinal parasites for the group tested using the stool concentration technique was 42.06% (male: 46.87%, females: 38.82%); and 22.66% (males: 28.92%, females: 18.20%) when using the Scotch-tape technique.Among helminth-infected individuals, enterobiasis was found at the highest prevalence (15.49%). Other common infections were ascariasis (9.78%), trichuriasis (5.90%) and hookworm infection (2.20%). Strongyloildiasis was found only in 0.92%. For protozoa infection, the major cause is the non-pathogenic species "Entamoeba coli" (27.68%). The other non-pathogenic protozoa (Endolimax nana, Chilomastix meslini and Iodamoeba butschlii) had a low prevalence from ranged 0.18%-4.79%. The prevalence of pathogenic Giardia lamblia infection was 2.21%. Entamoeba histolytica infection was found in only one case. Based on the two techniques used, the results from the Scotch-tape provided a higher sensitivity for the detection of Taenia spp. and Enterobius vermicularis eggs. Drug treatment was given to all the infected students. School-based health education should be implemented in order to prevent and control the infections.

Pneumocystis pneumonia: an update.

Pneumocystis pneumonia is a major cause of illness and death in immunocompromised hosts. The numbers of pneumocystis pneumonia cases in Thailand have increased each year from 1992 to 2000 and peaked in 2000 at 6,255 cases. The microbe that causes pneumocystis pneumonia in humans is called Pneumocystis jirovecii. Pneumocystis sp. was discovered nearly a century ago, but the knowledge of Pneumocystis sp. remained poorly understood, until the molecular biology techniques help scientists verify it fungus nature. In the past, Pneumocystis sp. was misclassified as protozoan due to its morphologic features. Later, it was reclassified as fungus due to DNA analysis. Cotrimaxazole, the combination of trimethoprim-sulfamethoxazole, is the drug of choice for treatment and prophylaxis of pneumocystis pneumonia. However, increasing evidence of mutations in the enzyme dihydropteroate synthase (DHPS), the target of sulfa drugs represent emergence of sulfa resistance.

Comparative assessment of an Og4C3 ELISA and an ICT filariasis test: a study of Myanmar migrants in Thailand.

Detection of circulating filarial antigen has now emerged as an alternative method for the diagnosis of bancroftian filariasis. We compared two antigen detection assays, an Og4C3 ELISA and an ICT (immunochromatography) Filariasis test, for the diagnosis of Wuchereria bancrofti infections in migrant Myanmar workers in Tak province, Western Thailand. A total of 337 Myanmars participated in this study. The microfilarial rate was 3.3%. The Og4C3 ELISA could detect 19.1% of bancroftian filariasis while the ICT test detected 12.7%. Both antigen assays could detect all microfilaremics. The Og4C3 ELISA detected 14.8% of amicrofilaremics while the ICT test identified 8.1%. Those who were positive for the ICT test were also positive by the Og4C3 ELISA. Those Og4C3 positive cases, that were ICT negative (ICT-ve/Og4C3+ve) had statistically significant (p < 0.05, unpaired t-test) lower Og4C3 antigen levels (409.5 units, range 117-2,389) than those that were ICT positive (ICT+ve/Og4C3+ve) (5,252.0 units, range 130-28,062). Our results emphasize the problem of bancroftian filariasis in Myanmar migrants working in Thailand. Close monitoring and control of this disease in Myanmar migrants are of public health importance. Antigen detection systems are promising tools for the surveillance of bancroftian filariasis.

Prevalence of bancroftian filariasis on the Thai-Myanmar border.

To achieve the goal of eliminating lymphatic filariasis by the year 2020, close monitoring systems and effective control strategies need to be implemented and the real disease burden needs to be assessed. Bancroftian filariasis is endemic at the Thai-Myanmar border. However, there are only limited data on the prevalence of this disease in Thailand available. We employed microscopic examination, together with ELISA kits to detect W. bancrofti-specific Og4C3 circulating antigen and specific anti-filarial IgG4 antibodies to determine the burden of bancroftian filariasis in an endemic area at the Thai-Myanmar border in Umphang District, Tak province, Thailand. A total of 433 Thai-Karen blood samples were analyzed. The microfilarial rate determined by microscope was 6% and the W. bancrofti-specific Og4C3 antigenemia rate was 22%, while the specific anti-filarial IgG4 antibody rate was 54%. There were statistically significant higher levels of W. bancrofti-specific Og4C3 antigen in the microfilaremic-antigenemic group than in the amicrofilaremic-antigenemic group (unpaired Student's t-test; p < 0.001), similar to the specific anti-filarial IgG4 antibody results (unpaired Student's t-test; p < 0.001). A statistically significant correlation of moderate degree between the presence of W. bancrofti-specific Og4C3 antigen and of specific anti-filarial IgG4 antibody was found in the amicrofilaremic group (r = 0.474, p < 0.001), but not in the microfilaremic group (r = 0.291, p > 0.05). Our study revealed a very high prevalence of bancroftian filariasis in this endemic area and thus emphasized the importance of using highly sensitive and specific diagnostic tools to evaluate the true prevalence of the disease.

Efficacy of albendazole against early and late stage of Trichinella spiralis infection in mice.

Efficacy of albendazole against early and late stage of Trichinella spiralis infection in mice was determined. To determine the efficacy of albendazole against the early stage (enteral phase) of trichinosis, mice experimentally infected with T. spiralis were treated with albendazole 20 mg/kg at 7 days post infection for 15 days. Larvae were recovered from the infected mice 7 days after the treatment. The reduction rate of the larvae was 100 per cent. Efficacy of albendazole against the late stage (parenteral phase) of infection was determined at 30 days post infection. Mice were treated with albendazole at 20 mg/kg for 30 days. Larvae were recovered from the infected mice 7 days after the treatment. The reduction rate of the larvae was 71 per cent compared to the control group. In conclusion, albendazole was more effective in the early stage of infection than the late stage, the reduction was 100 per cent and 71 per cent with respect to the control group respectively.

Intestinal parasitic infestations among children in an orphanage in Pathum Thani province.

Infection caused by intestinal parasites is still a common health problem especially in children from developing countries. Orphans are a group of underprivileged population in society. To evaluate the intestinal parasitic infections in children in an orphanage in Pathum Thani province, Thailand, stool samples were collected during a cross-sectional study in April 2001. Examination for intestinal parasites were performed by using simple smear, formalin-ether concentration, Boeck and Drbohlav's Locke-Egg-Serum (LES) medium culture and special staining (modified acid-fast and modified trichrome) techniques. A total of 106 pre-school orphans (60 males and 46 females), aged 10.0-82.0 months, were recruited for the study. There were 86 individuals (81.1%), 45 males and 41 females, infected with at least one parasite. Interestingly, most of the parasites identified were protozoa. Blastocystis hominis was found at the highest prevalence (45.2%). The infections caused by Giardia lamblia was 37.7 per cent and Entamoeba histolytica was 3.7 per cent. Other non-pathogenic protozoa found were Trichomonas hominis (39.6%), Entamoeba coli (18.8%), and Endolimax nana (3.7%). The only one case of helminth parasite detected was Strongyloides stercoralis (0.9%). The sensitivity for detection of B. hominis and T. hominis was increased by the LES culture technique. No history of diarrhea symptoms were recorded among these orphans. However, during the investigation, stools of all infected cases were noted for six characteristics including formed, soft, loose, mucous, loose-watery and watery. The present study emphasized the problems of protozoan infections among these orphans. Health educations as well as routine surveillance is necessary in order to control the infections.

Prevalence of parasitic infections among Thai patients at the King Chulalongkorn Memorial Hospital, Bangkok, Thailand.

Parasitic diseases are still considered to be a major public health problem. Most patients with parasitic infections are asymptomatic and therefore remain undetected. Asymptomatic parasitic infections are usually discovered by routine parasite examination. To determine the result of parasite examination at the Parasitology Unit, Out Patient Department, King Chulalongkorn Memorial Hospital, Bangkok, Thailand, the authors collected the data of individuals examined for parasite infections from June to December 1997. A total of 6,231 Thais provided the data for analysis. Evidence of parasitic infections was found in 557 (8.94%) cases. The disease was most prevalent in males (57.3%), and in the age group >15-30 years old (11.13%). The population from the Northeast of Thailand was found to harbor parasites with the highest prevalence rate (17.03%), while it was 11.90 per cent in the northern group. The parasitic prevalence rates in the West, East, South and Central regions were 10.60 per cent, 8.90 per cent, 7.74 per cent, and 4.92 per cent, respectively. The parasite most commonly identified was Strongyloides stercoralis (33.39%), while giardiasis was the most common protozoan infection (14.36%). The highest infection rates of S. stercoralis, hookworms, Opisthorchis viverrini, and Gnathostoma spinigerum were found in northeasterners. People from the North of Thailand were infected mostly with G. lamblia. People of working-age from northeastern as well as northern regions harbored pathogenic parasites with high prevalence rates. To prevent parasitic infections, health education for these high risk groups should be provided.

Prevalence and intensity of third stage Gnathostoma spinigerum larvae in swamp eels sold in three large markets in Bangkok, Thailand.

Gnathostoma spinigerum is a common human tissue parasite in Thailand. The swamp eel is the major intermediate or paratenic host for this parasite. The high prevalence of the infective third stage larvae (L3) of this parasite in the rainy season has been noted in previous studies. During June 1999 (rainy season), we performed a cross-sectional survey of the prevalence and the intensity of G. spinigerum L3s in the livers of swamp eels that were obtained from three large Bangkok markets (Klong Toey, Pran Nok, and Tevej). Of a total of 785 livers, G. spinigerum L3s were found in 97: an infection rate of 12%. The prevalence rates in Klong Toey, Pran Nok, and Tevej markets were 13%, 10% and 14% respectively. There was no significant difference in the proportion of infected eels between the markets (p > 0.05). The intensity of L3 burden in the livers ranged from 1-17 larvae, with an average of 2.60 +/- 0.24 larvae (mean +/- SE). In this study a high prevalence of G. spinigerum L3s was found; there was no significant difference in the intensity of larvae in swamp eels between markets. These findings emphasize the importance of public health education: people need to be aware of the dangers of consuming raw or undercooked food.

Parasitic infections in Thai workers that pursue overseas employment: the need for a screening program.

Stool examination is a requirement of the screening program for Thai workers seeking overseas employment. We report on the prevalence of intestinal parasitic infections among these workers; the stool examination results of 2,213 Thai workers who visited the Out-patients Department of the King Chulalongkorn Memorial Hospital between September 2000 and January 2001 were analysed. One hundred and thirty-five (6.1%) were found to be infected with 1 or 2 species of parasite. There were 54 (40%), 47 (34.8%), and 25 (18.5%) cases infected with nematodes, platyhelminths and protozoa, respectively. The commonest parasite was Opisthorchis viverrini (28.9%). Most nematode infections were due to Strongyloides stercoralis (19.2%); most protozoal infections were due to Giardia lamblia (17.0%). Mixed infections were found in 9 cases. Not unexpectedly, the rate of intestinal parasitic infection among Thai workers remains high. Screening for the parasitic infections among these workers can help to decrease their rate of rejection by the countries in which overseas employment is sought.