Predictive diagnostic value of the tourniquet test for the diagnosis of dengue infection in adults.

OBJECTIVE: To examine the accuracy of the admission tourniquet test in the diagnosis of dengue infection among Lao adults. METHODS: Prospective assessment of the predictive diagnostic value of the tourniquet test for the diagnosis of dengue infection, as defined by IgM, IgG and NS1 ELISAs (Panbio Ltd, Australia), among Lao adult inpatients with clinically suspected dengue infection. RESULTS: Of 234 patients with clinically suspected dengue infection on admission, 73% were serologically confirmed to have dengue, while 64 patients with negative dengue serology were diagnosed as having scrub typhus (39%), murine typhus (11%), undetermined typhus (12%), Japanese encephalitis virus (5%), undetermined flavivirus (5%) and typhoid fever (3%); 25% had no identifiable aetiology. The tourniquet test was positive in 29.1% (95% CI = 23.2-34.9%) of all patients and in 34.1% (95% CI = 27.0-41.2%) of dengue-seropositive patients, in 32.7% (95% CI = 23.5-41.8) of those with dengue fever and in 36.4% (95% CI = 24.7-48.0) of those with dengue haemorrhagic fever. Interobserver agreement for the tourniquet test was 90.2% (95% CI = 86.4-94.0) (Kappa = 0.76). Using ELISAs as the diagnostic gold standard, the sensitivity of the tourniquet test was 33.5-34%; its specificity was 84-91%. The positive and negative predictive values were 85-90% and 32.5-34%, respectively. CONCLUSIONS: The admission tourniquet test has low sensitivity and adds relatively little value to the diagnosis of dengue among Lao adult inpatients with suspected dengue. Although a positive tourniquet test suggests dengue and that treatment of alternative diagnoses may not be needed, a negative test result does not exclude dengue.

Causes of community-acquired bacteremia and patterns of antimicrobial resistance in Vientiane, Laos.

There is no published information on the causes of bacteremia in the Lao PDR (Laos). Between 2000 and 2004, 4512 blood culture pairs were taken from patients admitted to Mahosot Hospital, Vientiane, Laos, with suspected community-acquired bacteremia; 483 (10.7%) cultures grew a clinically significant community-acquired organism, most commonly Salmonella enterica serovar typhi (50.9%), Staphylococcus aureus (19.0%), and Escherichia coli (12.4%). S. aureus bacteremia was common among infants (69.2%), while children 1-5 years had a high frequency of typhoid (44%). Multi-drug-resistant S. Typhi was rare (6%). On multiple logistic regression analysis, typhoid was associated with younger age, longer illness, diarrhea, higher admission temperature, and lower peripheral white blood cell count than non-typhoidal bacteremia. Empirical parenteral ampicillin and gentamicin would have some activity against approximately 88% of clinically significant isolates at a cost of US $1.4/day, an important exception being B. pseudomallei. Bacteremic infants in this setting require an anti-staphylococcal antibiotic.

A randomized comparison of oral chloramphenicol versus ofloxacin in the treatment of uncomplicated typhoid fever in Laos.

We conducted a randomized open trial of oral chloramphenicol (50mg/kg/day in four divided doses for 14 days) versus ofloxacin (15 mg/kg/day in two divided doses for 3 days) in 50 adults with culture-confirmed uncomplicated typhoid fever in Vientiane, Laos. Patients had been ill for a median (range) of 8 (2-30) days. All Salmonella enterica serotype typhi isolates were nalidixic acid-sensitive, four (8%) were chloramphenicol-resistant and three (6%) were multidrug-resistant. Median (range) fever clearance times were 90 (24-224) hours in the chloramphenicol group and 54 (6-93) hours in the ofloxacin group (P<0.001). One patient in the chloramphenicol group developed an ileal perforation. Three days ofloxacin was more effective than 14 days chloramphenicol for the in-patient treatment of typhoid fever, irrespective of antibiotic susceptibility, and was of similar cost.

The infective causes of hepatitis and jaundice amongst hospitalised patients in Vientiane, Laos.

There is little information on the diverse infectious causes of jaundice and hepatitis in the Asiatic tropics. Serology (hepatitis A, B, C and E, leptospirosis, dengue, rickettsia), antigen tests (dengue), PCR assays (hepatitis A, C and E) and blood cultures (septicaemia) were performed on samples from 392 patients admitted with jaundice or raised transaminases (> or =x3) to Mahosot Hospital, Vientiane, Laos over 3 years. Conservative definitions suggested diagnoses of dengue (8.4%), rickettsioses (7.3%), leptospirosis (6.8%), hepatitis B (4.9%), hepatitis C (4.9%), community-acquired septicaemia (3.3%) and hepatitis E (1.6%). Although anti-hepatitis A virus (HAV) IgM antibody results suggested that 35.8% of patients had acute HAV infections, anti-HAV IgG antibody avidity and HAV PCR suggested that 82% had polyclonal activation and not acute HAV infections. Scrub typhus, murine typhus or leptospirosis were present in 12.8% of patients and were associated with meningism and relatively low AST and ALT elevation. These patients would be expected to respond to empirical doxycycline therapy which, in the absence of virological diagnosis and treatment, may be an appropriate cost-effective intervention in Lao patients with jaundice/hepatitis.

Three cases of intestinal capillariasis in Lao People's Democratic Republic.

Capillaria philippinensis is a rare zoonotic intestinal parasite that emerged in the 1960s. The outcome of intestinal capillariasis may be fatal if untreated in due time. We report three cases of intestinal capillariasis in Lao People's Democratic Republic (Lao PDR). The three patients were unrelated previously healthy young men (24, 26, and 27 years of age) with no underlying disease or immune depression. They had chronic diarrhea, abdominal pain, edema, and severe weight loss. Two of them acquired the infection in Thailand; the other patient had no travel history outside Lao PDR. All patients were seen several times in different hospitals before the diagnosis was made. All had concurrent parasite infections: Giardia lamblia, Entamoeba histolytica, Strongyloides stercoralis, Opisthorchis viverrini, and hookworm. The patients frequently consumed uncooked fish. After treatment with albendazole (400 mg/day for 21-30 days) all patients recovered. In Lao PDR, consumption of raw small freshwater fish is common. Therefore, the possibility of a capillariasis outbreak should be considered.

Limited diagnostic capacities of two commercial assays for the detection of Leptospira immunoglobulin M antibodies in Laos.

The diagnostic utility of immunochromatographic (Leptotek) and enzyme-linked immunosorbent assay (ELISA; Panbio) tests for the detection of Leptospira immunoglobulin M antibodies was assessed in febrile adults admitted in Vientiane, Laos. Both tests demonstrated poor diagnostic accuracy using admission serum (Leptotek sensitivity of 47.3% and specificity of 75.5%: ELISA sensitivity of 60.9% and specificity of 65.6%) compared to the Leptospira "gold standard" microscopic agglutination test.