To better understand the epidemiology of bacterial food borne pathogens in children, in relation to pathogens in meats from a market in rural Thailand, we collected 73 cultures samples from raw chicken, pork and fish at a local market where diarrheal disease surveillance was conducted. Standard methods were employed to isolate, identify and serotype enteric pathogens from children and food samples. Antibiotic susceptibility testing was performed. Ninety-seven percent of food samples were contaminated with at least one enteric pathogen. The pathogens most commonly isolated from food were Salmonella spp (84%), Arcobacter butzleri (74%) and Campylobacter spp (51%). The most common serovars of Salmonella obtained from humans with diarrhea were S. Risen, S. Stanley and S. Anatum. Most common serovars of Salmonella isolated from food were S. Anatum, S. Stanley, and S. Corvallis. Fifty-one percent and 25% of children infected with Salmonella and Campylobacter, respectively, infected with the same serotypes isolated from food samples, suggesting these pathogens are widespread in food and humans. Pulsed-field gel analysis of Salmonella spp revealed 65 pulsotypes, but no point-sources of salmonellosis were identified. Joint epidemiologic/laboratory studies are useful to describe the epidemiology of enteric pathogens in rural populations.

A man living in rural western Thailand presented with a well-demarcated pinkish plaque on the dorsal surface of the right hand, extending to several fingers ( Figure 1 ). Mild scale was present. The lesion was not pruritic or tender, and there was no sporotrichoid lymphadenopathy. The differential diagnosis included cutaneous deep fungal and atypical mycobacterial infections. A punch biopsy showed a mononuclear dermal infiltrate with multinucleated giant cells and scattered darkbrown, round sclerotic bodies resembling “copper pennies” ( Figure 2 ), features consistent with chromoblastomycosis, a cutaneous deep fungal infection. Oral terbinafine (anti-fungal sterol inhibitor) was administered at 250 mg two times daily for 2 weeks and then, 250 mg daily for 14 weeks, with progressive resolution. Chromoblastomycosis, caused by a saprophytic pigmented (dematiaceous) fungus, occurs in many tropical areas, including Thailand. 1 It may be acquired by traumatic implantation, such as a wood splinter contaminated with fungal elements. Regional lymphatic damage and malignant transformation may occur. Treatment options include oral anti-fungal medications and physical methods, the former often requiring lengthy courses, and responses vary.

The objective was to assess the association of enteric pathogens in diarrheal disease in a remote rural area in Thailand. Stool specimens were collected from 236 children aged 3 months to 5 years with acute diarrhea (cases) and from 236 asymptomatic controls. Standard microbiologic methods, and enzyme immunoassay for viral pathogens, Giardia, and Cryptosporidium, were used to identify enteric pathogens with susceptibility testing by disk diffusion. Campylobacter, Plesiomonas, Salmonella, and enterotoxigenic Escherichia coli were commonly isolated from cases and controls (22% versus 25%, 10% versus 11%, 6% versus 9%, and 10% versus 6%, respectively). Only Shigella, rotavirus, and adenovirus were identified significantly more frequently in cases than controls (9% versus 0%, 18% versus 3%, and 16% versus 2%, respectively), whereas Giardia lamblia was detected less often in cases than controls. Most pre-school children were infested with enteric pathogens; laboratory-based studies are important to understand the epidemiology of enteric pathogens in remote areas among marginal populations.

A man living in rural western Thailand presented with a well-demarcated pinkish plaque on the dorsal surface of the right hand, extending to several fingers (Figure 1). Mild scale was present. The lesion was not pruritic or tender, and there was no sporotrichoid lymphadenopathy. The differential diagnosis included cutaneous deep fungal and atypical mycobacterial infections. A punch biopsy showed a mononuclear dermal infiltrate with multinucleated giant cells and scattered dark-brown, round sclerotic bodies resembling “copper pennies” (Figure 2), features consistent with chromoblastomycosis, a cutaneous deep fungal infection. Oral terbinafine (anti-fungal sterol inhibitor) was administered at 250 mg two times daily for 2 weeks and then, 250 mg daily for 14 weeks, with progressive resolution. Figure 1. Well-demarcated plaque on the dorsal surface of hand. This figure appears in color at www.ajtmh.org. Figure 2. Histology shows mononuclear cell infiltrate and a dark-brown, round sclerotic body resembling a “copper penny” (arrow), consistent with chromoblastomycosis (hematoxylin-eosin stain; 1,000×). This figure appears in color at www.ajtmh.org ... Chromoblastomycosis, caused by a saprophytic pigmented (dematiaceous) fungus, occurs in many tropical areas, including Thailand.1 It may be acquired by traumatic implantation, such as a wood splinter contaminated with fungal elements. Regional lymphatic damage and malignant transformation may occur. Treatment options include oral anti-fungal medications and physical methods, the former often requiring lengthy courses, and responses vary.1,2 Here, we speculate that terbinafine dosed at 500 mg daily for the first 2 weeks, a less commonly prescribed higher daily dose, may have been beneficial.

This study was conducted to investigate the presence of intestinal parasites among pre-school children (aged 3 months to 5 years) in Sangkhlaburi, a rural district in the west of Thailand along the Thai-Myanmar border. Stool specimens were collected from October 2001 through October 2002. A total of 472 pre-school children, 233 males and 239 females, 236 children with diarrhea and 236 asymptomatic children were recruited for the Study. Each specimen was processed and examined by direct wet smear, modified acid fast stain, formalin-ethylacetate sedimentation concentration technique, and trichrome stain. In detecting Giardia lamblia and Cryptosporidium species ProSpecT Microplate assays (Alexon-Trend, Lenexa, KS) were performed. There were 107 individuals (22.7%), 41 diarrheal and 66 asymptomatic children, infected with intestinal parasites. The most frequent parasites identified in cases and controls were G. lamblia and Cryptosporidium spp. Eighteen specimens (3.8%) showed mixed parasite infections. Highest proportion of intestinal parasites occurred during the rainy season (June-October).

Azithromycin, the most potent antimalarial macrolide antibiotic, is synergistic with quinine against Plasmodium falciparum in vitro. We assessed combinations of azithromycin and quinine against uncomplicated P. falciparum malaria at the Armed Forces Research Institute of Medical Sciences-Kwai River Clinical Center along the Thailand-Myanmar border, an area with a high prevalence of multidrug-resistant P. falciparum. Four regimens were assessed in an open-label dose-ranging design involving 61 volunteers. All received oral quinine (Q; 30 mg/kg/day divided every 8 hours for 3 days) with oral azithromycin (Az; 500 mg twice a day for 3 days, 500 mg twice a day for 5 days, or 500 mg three times a day for 3 days). A comparator group received quinine and doxycycline (Dx; 100 mg twice a day for 7 days). Study observation was 28 days per protocol. Sixty volunteers completed the study. Seven days of QDx cured 100% of the volunteers. One failure occurred in the lowest QAz regimen (on day 28) and none occurred in either of the two higher Az regimens. Cinchonism occurred in nearly all subjects. Overall, the azithromycin regimens were well tolerated, and no volunteers discontinued therapy. Three- and five-day azithromycin-quinine combination therapy appears safe, well tolerated, and effective in curing drug-resistant P. falciparum malaria. Further evaluation, especially in pediatric and obstetric populations, is warranted.

A hospital-based study was conducted along the Thai-Myanmar border to provide greater knowledge of the causes of febrile illness and to determine what zoonotic and vector-borne emerging infectious diseases might be present. A total of 613 adults were enrolled from June 1999 to March 2002. Cases were classified based on clinical findings and laboratory results. An etiologic diagnosis was made for 48% of subjects. Malaria was the most common diagnosis, accounting for 25% of subjects, with two-thirds Plasmodium falciparum. Serologic evidence for leptospirosis was found in 17% of subjects. Other etiologic diagnoses included rickettsial infections, dengue fever, and typhoid. The most frequent clinical diagnoses were nonspecific febrile illness, respiratory infections, and gastroenteritis. Clinical associations were generally not predictive of etiologic diagnosis. Apparent dual diagnoses were common, particularly for malaria and leptospirosis. Findings have been used to modify treatment of unspecified febrile illness in the area.

Molecular markers have been proposed as a method of monitoring malaria drug resistance and could potentially be used to prolong the life span of antimalarial drugs. Single nucleotide polymorphisms (SNPs) in the Plasmodium falciparum gene pfmdr1 and increased gene copy number have been associated with in vitro drug resistance but have not been well studied in vivo. In a prospective cohort study of malaria patients receiving mefloquine treatment on the Thai-Myanmar border, there was no significant association between either pfmdr1 SNPs or in vitro drug sensitivity and mefloquine resistance in vivo. Increased pfmdr1 gene copy number was significantly associated with recrudescence (relative risk 2.30, 95% CI 1.27-4.15). pfmdr1 gene copy number may be a useful surveillance tool for mefloquine-resistant falciparum malaria in Thailand.

We assessed the prophylactic efficacy of azithromycin (250 mg/day) against malaria in 276 adults in western Thailand in a randomized, double-blind, placebo-controlled trial. After antimalarial suppressive treatment, volunteers were randomized in a 2:1 ratio to either the azithromycin or placebo, respectively. Study medication was given for an average of 74 days. The azithromycin group (n = 179) had five endpoint parasitemias (1 Plasmodium vivax and 4 P. falciparum), and the placebo group (n = 97) had 28 endpoint parasitemias (21 P. vivax, 5 P. falciparum, and 2 mixed infections). Adverse events and compliance and withdrawal rates were similar in both groups. The protective efficacy (PE) of azithromycin was 98% for P. vivax (95% confidence interval [CI] = 88-100%). There were too few cases to reliably estimate the efficacy of azithromycin for P. falciparum (PE = 71%, 95% C = -14-94%). We conclude that daily azithromycin was safe, well-tolerated, and had a high efficacy for the prevention of P. vivax malaria.

We have performed a case-control analysis to determine the significance of clinical, laboratory and epidemiological features as predictive factors of rickettsioses among patients in Sangkhla Buri, Thailand (Thai-Myanmar border). Fifteen serologically-confirmed rickettsiosis patients including Spotted Fever Group (SFG) rickettsioses, scrub typhus, and murine typhus were classified as 'cases'; one hundred and sixty-three acutely febrile patients presenting to the same hospital during the same time period, who had no serological evidence of acute rickettsiosis, were classified as 'controls'. Patients' report of rash/arthropod bite [Odds ratio (OR) 22.90, 95% CI (confidence interval) 6.23, 84.13] and history of jungle trips (OR 5.30, 95% CI 1.69-16.62) were significant risk factors. Elevated ALT (OR 3.04, 95% CI 1.04, 8.88) and depressed platelet count (OR 3.38, 95% CI 1.13, 10.10) were also useful differentiating markers of rickettsioses in this population. Definitive diagnosis of rickettsioses is difficult without specialized diagnostic capabilities that are rarely available in remote areas such as Sangkhla Buri, where other acute febrile illnesses with similar presentation are commonly found. The relative importance of predictive factors presented here may provide clinicians with some useful guidance in distinguishing rickettsioses from other acute febrile illnesses. Timely administration of empiric treatment in highly suspicious cases can deter potential morbidity from these arthropod-borne infections.

To investigate the presence of rickettsioses in rural residents of the central Thai-Myanmar border, we tested the blood of 46 patients with fever. Four patients had murine typhus, three patients had scrub typhus, and eight patients had spotted fever group rickettsioses, including the first case of Rickettsia felis infection reported in Asia.

Malaria and leptospirosis are both common in the tropics. Simultaneous infections are possible, although not previously reported. We report two cases of malaria from an area of Thailand on the Thailand-Myanmar border with compelling serologic evidence of simultaneous acute leptospirosis. One was a case of infection with Plasmodium falciparum with acute and convalescent microscopic agglutination test (MAT) titers for Leptospira serovar icterohaemorrhagiae of 1:200 and 1:1,600, respectively. The other was a case of infection with P. vivax that seroconverted to a titer of 1:3,200 for Leptospira serovar bataviae. Additionally, there were five probable cases of leptospirosis with patent malaria parasitemia (three P. falciparum and two P. vivax) detected. Management of dual infections is complicated by their similar clinical presentations, and because the confirmatory diagnosis of malaria is readily available as opposed to that of leptospirosis. Treatment focusing on malaria mono-infections instead of dual infections could result in a delay of specific therapy for leptospirosis and possible consequences of serious complications.

Moody et al (2000) reported a study carried out at the Hospital for Tropical Diseases, London, that showed the correlation between the presence of parasite lactate dehydrogenase enzyme (pLDH) in blood, as indicated by a malaria antigen capture dipstick assay 'OptiMAL', and the viability of falciparum malaria parasites following treatment. They concluded that OptiMAL is useful for the sequential follow-up of patients. Our observation during a clinical trial of quinine combination therapy in semi-immune individuals living in a malaria endemic area on the Thai–Myanmar border supports these findings, but further illustrates the caveat of gametocyte detection by OptiMAL after treatment. Twelve uncomplicated falciparum malaria patients were admitted to the Kwai River Christian Hospital, Sangkhlaburi, Thailand, for 4 weeks and were monitored daily using Giemsa thick-and-thin blood smear and OptiMAL until the Giemsa smears had become negative for asexual parasites for 7 d, and thereafter weekly on d 14, 21 and 28. All cases were OptiMAL positive on admission. Giemsa blood smears became negative (for asexual parasites) on d 3 in two cases, d 4 or 5 in nine cases, and d 6 in one case. Three cases became OptiMAL negative on d2 and nine cases on d3, on average 1·7 d earlier than the Giemsa smears. Furthermore, OptiMAL test line intensity progressively declined, paralleling the levels of parasitaemia. The median parasite density at diagnosis (d 1) was 53 176/μl (range 907–184 032/μl). At the time OptiMAL turned negative, median (asexual) parasite density was 113/μl (range 12–480/μl). For the total of 72 samples that were Giemsa negative for both asexual- and sexual-stage parasites, all were OptiMAL negative, giving a specificity of 100%. The P. falciparum gametocyte is known to secrete pLDH (Oduola et al, 1997). Based on five P. falciparum gametocyte-only cases detected on the initial visit, Moody et al (2000) found OptiMAL sensitivity to be 80% and commented that poorer sensitivity (than that for asexual forms) was probably associated with the generally low-density gametocytaemia. No effect of gametocytaemia after treatment on the OptiMAL test results was mentioned. Interestingly, four of our patients developed gametocytes during follow-up when asexual parasitaemia was cleared or almost cleared. One had < 15 gametocytes/μl on two occasions and OptiMAL tests were negative both times. Two cases were gametocytaemic for over 2 weeks after clearance of asexual parasites and the last case maintained gametocytaemia from d 4 (Giemsa became negative for asexual parasites on d 3) until discharge (d 28). Parallel blood smears and OptiMAL tests were extended to monitor gametocytaemia every other day for these three cases. OptiMAL was also positive throughout for the last case (range of gametocyte densities: 31–634/μl). In all there were 45 gametocyte-only positive samples from these four patients. OptiMAL sensitivity was 88% for gametocyte densities ≥ 100/μl (22 out of 25; maximum 968/μl) and 35% (7 out of 20) for densities < 100/μl. In comparison, for P. falciparum asexual parasitaemia of under 500/μl, the sensitivity of OptiMAL has been documented in combined data from Thailand and Peru at 53% (Gasser et al, 2000). In general, OptiMAL is superior to histidine-rich protein 2 (HRP2)-based tests for sequential treatment follow-up because of the false positivity of the latter in association with persistent HRP2 antigenaemia in the absence of circulating parasites. Our observation suggests that the gametocyte is a potent pLDH producer, perhaps more so than asexual parasites, and is detectable by OptiMAL. Reversion, and possibly persistence as well, of OptiMAL positivity after treatment has to be interpreted with caution in relation to the therapeutic decision as it does not necessarily indicate recrudescence or failure of asexual parasite clearance.

Intrigued by the occurrence of malaria-smear-negative fever at a field site in Sangkhlaburi District, Kanchanaburi Province, Western Thailand on the Thai-Burmese border, we retrospectively tested serum samples collected from 50 healthy volunteers in a malaria prophylaxis study to determine the point prevalence of antibody to Ehrlichia chaffeensis. The Rickettsiaceae recognised as human pathogens in Thailand are Coxiella burnetii Orientia tsutsugamushi, and Rickettsia typhi. Clinical and serological evidence exists for tick-borne rickettsial spotted fever, but isolates have only been made from ticks.