Hookworm infections of schoolchildren in southern Thailand

A study of hookworm infections of schoolchildren was conducted in Nakhon Si Thammarat Province, southern Thailand. Of the 2,940 hookworms that were recovered from the children, almost all (99.9%), were Necator americanus, only three (0.1%) were identified as Ancylostoma duodenale, and all were female worms. An estimation of the worm burden of and the worm expulsion from the schoolchildren indicated there were 17 cases of light intensity hookworm infection. Fifteen cases (88.2%) expelled worms in numbers that corresponded with the worm burden that was estimated from the number of eggs per gram of feces. Two cases (11.8%) expelled more worms than predicted. In 16 moderate intensity cases, five (31.3%) expelled worms in a quantity that corresponding with the estimated worm burden. Eleven cases (68.7%) expelled fewer worms than predicted. All cases of heavy intensity infection expelled fewer worms than predicted.     

Molecular characterization of hemoglobin C in Thailand

We describe hematologic and DNA characterization of 12 hemoglobin C heterozygotes and three compound heterozygotes for hemoglobin C and hemoglobin E found in Thailand. Amplification and DNA analysis of genomic DNA by the polymerase chain reaction procedure permitted the identification of the beta(C) mutation at codon 6 of beta-globin gene (beta 6; GAG-AAG). beta-Globin gene haplotype analysis demonstrated that all beta(C) globin genes detected in these Thai individuals were associated with the haplotype (+ - - - - - +), indicating a non-African origin of this abnormal hemoglobin in Thailand. On routine hemoglobin typing, hemoglobin C is usually mistakenly identified as hemoglobin E because of theirs similar mobilities on cellulose acetate electrophoresis. The simple DNA assay for hemoglobin C based on an allele-specific polymerase chain reaction for accurate diagnosis of hemoglobin C was therefore developed.     

Molecular characterisation of the hepatitis A virus circulating in the 2001-2005 outbreaks in Thailand

In a recent study of hepatitis A virus (HAV) in Thailand, viral isolates recovered during several outbreaks of infection that occurred between 2001 and 2005 were genotyped and subjected to phylogenetic analysis. Anti-HAV IgM was detected, by ELISA, in many of the 283 serum samples that were collected from the provinces of Suphanburi, Songkhla, Chiangrai and Lampang: 40 (48.2% of those investigated), 38 (47.5%), 25 (41.0%) and 32 (54.2%), respectively. The HAV RNA in the positive samples was reverse transcribed and amplified, using a nested PCR focussed on the VP1-2A region, before the nucleotides of the VP1-2A region of each HAV-RNA-positive sample were sequenced. All the isolates investigated clustered in subgenotype IA and, hence, are closely related to the strains previously investigated in Thailand. When the genome of one sample from an outbreak in Lampang (LP014) was fully sequenced, the results of genome comparison and phylogenetic analysis again indicated subgenotype 1A, which appears to be the predominant form of HAV circulating throughout Thailand.     

The prevalence of urethral infections amongst asymptomatic young men in Hat Yai, southern Thailand

The aim of this study was to survey sexual behaviour and estimate the prevalence of urethral infections amongst male vocational college students. A cross-sectional survey was performed among 479 young men attending 2 vocational colleges in Hat Yai, southern Thailand. Polymerase chain reaction (PCR) tests of first-void urine (FVU) samples were used to detect infection with Chlamydia trachomatis, Neisseria gonorrhoeae, Ureaplasma urealyticum, Mycoplasma genitalium and Mycoplasma hominis. Girlfriends were the usual sexual partners for 89% of men with only 11% regularly patronizing sex workers. Condom usage was low. The prevalence of any urethral infection was 15.9% with: C. trachomatis 4%, N. gonorrhoeae 0.2%, U. urealyticum 10.9%, M. genitalium 2.3% and M. hominis 1.3%. Infection with more than one organism was found in 2% of men. While the prevalence of infection with chlamydia or gonorrhoea was relatively low, the prevalence of 'any urethral infection' was moderately high and suggests that unprotected sexual intercourse is commonly occurring. As girlfriends were the most usual sexual partners, they must be at significant risk of pelvic infection. There is a need for programmes targeting this group of people.     

Molecular characterization of haemophilia A in southern Chinese

41 unrelated southern Chinese haemophilia A patients were studied. The 5' promoter region, all 26 exons, their immediate 5' and 3' flanking splice junctions and the 3' untranslated region of the FVIII gene were amplified (including 16 different segments of exon 14) using GC-clamped primers. The GC-clamped PCR products were screened by denaturing gradient gel electrophoresis (DGGE) and fragments showing an abnormal migration pattern were sequenced. 17 mutations were identified, of which four were splicing defects, involving the first 1–6 nucleotide (nt) in the intervening sequences (IVS), six missense mutations, three nonsense mutations and four frameshift mutations. 14 other patients carried the type 1 inversion, affecting the distal copy of the F8A gene at the telomere of the X chromosome and the same gene in intron 22 of the FVIII gene. All the mothers studied (12/14) were carriers of the inversion. Two of these patients with inversion also have a co-existing missense mutation. In most cases the clinical severity of the disease corresponds to the genotype.     

Soil contamination and infections by soil-transmitted helminths in an endemic village in southern Thailand

The aim of this study was to test the association between soil contamination and infection of the household members by soil-transmitted helminths in dry and rainy seasons. A lake-side community in southern Thailand with a population of 2,340 was studied twice, in the dry season and rainy season of 1995. Fifty households were randomly selected. Soil samples near the latrine, in the yard, at the foot-washing area and under the trees were taken and analysed for presence of helminthic eggs. All members of the selected household were interviewed and stool samples obtained. Age-adjusted odds ratios of presence of Ascaris and Trichuris eggs in the household soil for ascariasis and trichuriasis were 10.5 (95% CI 1.5-77.1) and 5.5 (95% CI 2.4-12.7) in dry season and 10.4 (95% CI 2.5-43.8) and 8.3 (95% CI 3.4-20.0) in rainy season. The levels of hookworm eggs detected in the soil were too low to test the association. Soil analysis for eggs of Ascaris and Trichuris may be used to predict infections among the household members but not that for hookworm.     

Foodborne disease outbreaks of chemical etiology in Thailand, 1981-1987

A study was conducted to determine the current situation of chemical foodborne outbreaks in Thailand for the period 1981-1987. Seventy-three outbreaks of chemical poisoning involving 1236 persons of whom 54 died were reported. Twenty outbreaks affecting 722 cases were caused by insecticide poisoning and methomyl was the most commonly recognized insecticide involved. Poisonous plants were responsible for 43 outbreaks with 420 cases. Mushroom poisoning was the most common entity (21 outbreaks, 211 cases), with plant seed poisoning next (9 outbreaks, 179 cases). There were 8 outbreaks following consumption of poisonous seafoods. Mussels were identified to be the vector in the outbreak of PSP. Horseshoe crabs which served as the vehicles for 4 outbreaks were also suspected to be associated with PSP. Puffer fish accounted for the remaining 3 outbreaks involving 6 cases of tetradotoxin poisoning. More complete reporting and more effort in outbreak investigations are needed for appropriate preventive and control measures.     

Pseudomonas pseudomallei in southern Thailand

The distribution of Pseudomonas pseudomallei was studied in soil and water from various sources of Songkla province, Southern Thailand. P. pseudomallei was isolated from the surface soil of rubber plantations (60.9%) and from the bottom sediments of rice fields (78.1%). Farmers and plantation workers will have a greater risk of contracting melioidosis.     

Molecular characterization of hereditary persistence of fetal hemoglobin in the Karen people of Thailand

Hereditary persistence of fetal hemoglobin (HPFH) is the condition whereby a continuously active gamma-globin gene expression leads to elevated fetal hemoglobin (Hb F) levels in adult life [Stamatoyannopoulos G, Grosveld F. Hemoglobin switching. In: Stamatoyannopoulos G, Majerus PW, Perlmutter RM, Varmus H, eds. The Molecular Basis of Blood Diseases. Philadelphia: W.B. Saunders, 2001:135-182; Wood WG. Hereditary persistence of fetal hemoglobin and delta(beta) thalassemia. In: Steinberg MH, Forget BG, Higgs DR, Nagel RL, eds. Disorders of Hemoglobin: Genetics, Pathophysiology, and Clinical Management. Cambridge: Cambridge University Press, 2001:356-388; and Weatherall DJ, Clegg JB. Hereditary persistence of fetal hemoglobin. In: Weatherall DJ, Clegg JB, eds. The Thalassaemia Syndromes. Oxford: Blackwell Scientific Publishers, 1981:450-507]. The condition is caused either by mutation of the beta- and gamma-globin genes, or the gamma-gene controlled region on other chromosomes. Several families with this condition have been reported from Vietnam, Cambodia and China, and the Southeast Asian mutation (or HPFH-6), a 27 kb deletion, was demonstrated. Here we report on a mother and her daughter of the Karen ethnic group with high levels of Hb F, living in the Suan Pueng District on the border of Thailand and Myanmar. Genotyping showed a heterozygosity for the 27 kb deletion of the beta-globin gene. Their conditions have been confirmed by gap polymerase chain reaction (PCR) with three oligonucleotide primers recently developed by Xu et al. [Xu X-M, Li Z-Q, Liu Z-Y, Zhong X-L, Zhao Y-Z, Mo Q-H. Molecular characterization and PCR detection of a deletional HPFH: application to rapid prenatal diagnosis for compound heterozygotes of this defect with beta-thalassemia in a Chinese family. Am J Hematol 2000; 65:183-188.], and a DNA sequencing method. Thus far there has been no official report of the HPFH-6 anomaly from Thailand. The compound heterozygosity of beta-thalassemia (thal) and hereditary persistence of Hb F causes the phenotype of thalassemia intermedia; in contrast, homozygotes for this anomaly show only mild microcytic anemia. Hence, genetic counseling for hereditary persistence of Hb F carriers is needed for family planning.     

Molecular epidemiology of bacterial infections: examples of methodology and of investigations of outbreaks

Plasmid profile analysis, plasmid and chromosomal bacterial restriction endonuclease DNA analysis, and DNA hybridization are increasingly used in clinical microbiology and epidemiology. These techniques have been applied, singly and in combination, to investigations of outbreaks, including those of diarrheal diseases caused by pandemic Vibrio cholerae, enterotoxigenic and enterohemorrhagic Escherichia coli, Salmonella muenchen, and Salmonella typhimurium. The techniques have been critical in the unraveling of outbreaks of disease caused by nosocomial and community-acquired pathogens. Although there are limitations to these methods, their applications have important ramifications for basic science and public health.     

Molecular characterization of Campylobacter isolated from chickens and humans in northern Thailand

A study was conducted in northern Thailand to characterize Campylobacter spp isolated from chickens at farms, slaughterhouse, and chicken meat at fresh markets, and stools from chicken farmers as well as neighboring crop farmers who served as controls. The Campylobacter isolates were collected during the rainy months of the years 2000, 2001, and 2002. Standard methods were used for primary isolation and identification of Camplobacter and the resulting isolates were frozen and stored in 30% glycerol with Mueller-Hinton broth at -70 degrees C until used in 2003. A multiplex PCR assay was used for differentiation of the Campylobacter spp. A total of 415 Campylobacter spp were isolated from 849 (48.9%) samples from chickens at the farm, slaughter house and fresh chicken meat market. Campylobacter spp were isolated from 5 of the 129 (3.9%) chicken farmers but none from the 100 neighboring crop farmers. C. jejuni was the most prevalent (42.5%) at the farm, followed by C. coli (39.1%) and other species (8.0%). In contrast, C. coli was the most prevalent at the slaughter house (72.4%) while C. jejuni was only 17.2% and others 3.4%. Similarly, at the fresh chicken market, C. coli was the most prevalent (54.4%) while C. jejuni was 26.5% and others were 13.2%. Campylobacter spp isolated from the chicken farmers were predominantly (75%) C. coli and the rest (25%) were C. jejuni. The results of the study show that both C. coli and C. jejuni are highly prevalent in chickens, along the chicken production system and in chicken farmers in northern Thailand. Critical control points for exposure and contamination of the chicken meat supply should be identified so that methods can be developed to protect human exposure to Campylobacter spp.     

Brackish-water mollusks of Surat Thani Province, southern Thailand

Brackish-water mollusks inhabiting the mangrove areas along the Gulf of Thailand of Surat Thani Province were investigated for distribution, abundance and natural infections. Nine families and 32 species of brackish-water snails were recovered from 14 sampling stations. Species belonging to the genus Ceritidea of the family Potamididae were mainly examined and Cerithidea (Cerithideopsilla) Cingulata, C. (C.) djadjariensis, and C. (Cerithidea) charbonnieri were naturally infected with 2 types of trematode cercariae, and one which was undetermined. C. (C.) cingulata had the highest infection rate (38.5%). Viewing two snail communities, the first community on the mainland and the second on Samui Island in Surat Thani Province, 28 brackish-water mollusk species were present on the mainland, 15 species were evident on Samui Island, and 11 snail species were common to both the mainland and Samui Island. Measurement of community similarity based on species presence revealed an index of similarity of 0.51. Concerning land use by the local people in the station areas investigated, brackish-water snails in Surat Thani Province are facing habitat degradation by human use.     

Surveillance of food poisoning outbreaks in Thailand 1981-1986

In the period of 1981-1986, eighteen outbreaks of food poisoning following ingestion of insecticide contaminated food were reported to the Division of Epidemiology, Ministry of Public Health. There were 678 individuals experiencing illness, of which 9 cases died. Out of 18 outbreaks, 16 involving 615 cases resulted from carbamate (Methomyl and Propoxur) intoxications. The remaining two outbreaks were caused by organophosphate (Coumaphos) and organochlorine (DDT). The case fatality rate was much higher with Coumaphos than Methomyl; and no death was reported among Propoxur and DDT victims. Desserts and beverages were found to be the main vehicles, and private home was the most common place for the outbreaks of food poisoning caused by ingestion of insecticide contaminated food.     

Malaria and Hepatocystis species in wild macaques, southern Thailand

Southeast Asian macaques are natural hosts for a number of nonhuman primate malaria parasites; some of these can cause diseases in humans. We conducted a cross-sectional survey by collecting 99 blood samples from Macaca fascicularis in southern Thailand. Giemsa-stained blood films showed five (5.1%) positive samples and six (6.1%) isolates had positive test results by polymerase chain reaction. A phylogenetic tree inferred from the A-type sequences of the small subunit ribosomal RNA gene confirmed Plasmodium inui in five macaques; one of these macaques was co-infected with P. coatneyi. Hepatocystis, a hemoprotozoan parasite transmitted by Culicoides, was identified in an isolate that was confirmed by analysis of mitochondrial cytochrome b sequences. All malaria-infected monkeys lived in mangrove forests, but no infected monkeys were found in an urban area. These findings indicate regional differences in malaria distribution among these macaques, as well as differences in potential risk of disease transmission to humans.     

Molecular characterization of Mycobacterium tuberculosis isolated in the State of Parana in southern Brazil

Sequence IS6110 has been successfully used throughout the world for characterizing the Mycobacterium tuberculosis lineages. The aim of this study was to obtain data about circulating strains of M. tuberculosis in patients from the State of Parana in southern Brazil. Sixty-two clinical specimens obtained from sputum, bronchial aspirate, biopsy and urine from 62 patients clinically diagnosed with tuberculosis and admitted to the SUS-Brazil - The Brazilian Centralized Health Service System - were genotyped by the mixed-linker PCR DNA fingerprinting technique. The analysis demonstrated that the number of copies of the IS6110 sequence per isolates varied from four to 13 bands, with an average number of 8.5. From this, 93% of the isolates presented multiple copies. Isolates with no copies of the IS6110 element were not observed. The genetic analysis by UPGMA grouped the 62 isolates by similarity into three different groups: the first group contained two strains, the second was composed of 23, and the third, a more heterogeneous group, contained 37 isolates. Only two isolates (3.2%) formed a cluster; in other words, they presented a pattern of polymorphism with similarity above 95%. Such findings suggest that in the State of Parana, illness predominantly develops through reactivation of the latent infection as opposed to exogenous transmission. The methodology used (mixed-linker PCR DNA fingerprinting) allowed for 93.5% differentiation of the isolates tested, and proved to be a powerful tool for differentiation in the molecular genotyping of M. tuberculosis.     

Case reports of neuro-Chikungunya in southern Thailand

There has been a recent increase in reports of neurologic complications as major causes of morbidity and mortality in chikungunya virus infection. As a part of 2004-2009 global outbreaks, an unprecedented large chikungunya epidemic occurred in Southern Thailand during 2008-2009 in which 49,069 cases were reported. During this period, we encountered two patients with meningoencephalitis and another patient with myeloneuropathy among 1,018 cases diagnosed as chikungunya in our hospital. The clinical pictures are presented and the key points are used to recognize and differentiate chikungunya from Japanese encephalitis virus, dengue virus, and herpesvirus infections, which are more common causes of meningoencephalitis and myelitis in this region.     

Molecular diversity of human parvovirus B19 during two outbreaks of erythema infectiosum in Brazil

This study was conducted to provide information on the genetic diversity of human parvovirus B19 (B19V) circulating in the municipality of Niterói, Rio de Janeiro, Southeast Brazil during 1996–2006, a period with two distinct outbreaks of B19V infection: 1999–2000 and 2004–2005. A total of 27 sera from patients with erythema infectiosum and five sera from HIV-infected patients that tested positive for B19V DNA during the study period were analyzed. To genotype B19V strains, a semi-nested PCR for partial amplification of the capsid gene was performed and sequence analysis revealed that 31 sequences belonged to subgenotype 1a (G1a) of the main genotype 1 and one sequence was characterized as subgenotype 3b (G3b). The phylogenetic tree supported the division of the G1a into two well-defined clades with 1.3% of divergence. The low diversity of the G1a strains may be explained by the fact that all patients had acute B19V infection and 30/32 sera were collected during two distinct outbreaks. The G3b strain was from an HIV-infected patient who seroconverted to anti-B19 IgG antibodies in September/2005. This is the first report of G3b in the state of Rio de Janeiro.