Abstract. Scrub typhus is endemic in Thailand. Of the 495 patients with acute undifferentiated fever studied in Maharat Nakhon Ratchasima Hospital, Nakhon Ratchasima, Thailand, from June 1, 2011, to December 31, 2012, 146 patients (29.5%) had confirmed scrub typhus. The majority of cases were male, farmers, with the mean (±standard deviation) age of 54.1 ± 15.2 years. A total of 59 patients (40.4%) had eschar lesion. The commonest sites for an eschar in male patients were the perineum, inguinal, and buttock area; whereas in females, it was the head and neck area. Abnormal electrocardiogram was found in 39 of 79 patients (49.4%) with sinus tachycardia being the most frequent finding (17, 21.5%). A total of 73 patients (50%) had at least one complication. Myocarditis was the cause of complete heart block in a scrub typhus patient, and he fully recovered after receiving intravenous chloramphenicol treatment. The case fatality rate was 6.2% (nine deaths).The independent predictors for fatal outcome were age over 65 years (odds ratio [OR] = 14.49, 95% confidence interval [CI] = 1.26-166.44, P = 0.03), acute kidney injury (OR = 12.75, 95% CI = 1.77-92.07, P = 0.01), and hyperbilirubinemia (OR = 24.82, 95% CI = 2.12-286.61, P = 0.01). Early diagnosis and prompt appropriate treatment can improve the patient's outcome.

The objective of this study was to determine the changing trend of leptospirosis over time in Thailand using two prospective hospital-based studies conducted amongst adult patients with acute undifferentiated fever (AUFI) admitted to Maharat Nakhon Ratchasima Hospital, Nakhon Ratchasima Province, Thailand between July 2001 to December 2002 and between July 2011 to December 2012. During the first period, leptospirosis (98 patients, 40%) and scrub typhus (59 patients, 24.1%) were the two major causes of AUFI. In the second period, scrub typhus (137 patients, 28.3%) was found to be more common than leptospirosis (61 patients, 12.7%). Amongst patients with leptospirosis, the proportion of male patients and the median age were similar. Leptospira interrogans serogroup Autumnalis was the major infecting serogroup in both study periods. The case fatality rate of leptospirosis was significantly higher in 2011–2012 as compared with the case fatality rate in 2001–2002 (19.7% vs. 6.3%, p < 0.001). In summary, we found that number of leptospirosis cases had decreased over time. This trend is similar to reportable data for leptospirosis complied from passive surveillance by the Ministry of Public Health, Thailand. However, the case fatality rate of severe leptospirosis has increased. Severe lung hemorrhage associated with leptospirosis remained the major cause of death.

Scrub typhus, caused by Orientia tsutsugamushi, is a common cause of acute undifferentiated febrile illness in the Asia-Pacific region. However, its nonspecific clinical manifestation often prevents early diagnosis. We propose the use of PCR and serologic tests as diagnostic tools. Here, we developed a multiplex real-time PCR assay using hydrolysis (TaqMan) probes targeting O. tsutsugamushi 47-kDa, groEL, and human interferon beta (IFN-␤ gene) genes to improve early diagnosis of scrub typhus. The amplification efficiency was higher than 94%, and the lower detection limit was 10 copies per reaction. We used a human gene as an internal DNA quality and quantity control. To determine the sensitivity of this PCR assay, we selected patients with confirmed scrub typhus who exhibited a clear 4-fold increase in the level of IgG and/or IgM. The PCR assay result was positive in 45 of 52 patients, indicating a sensitivity of 86.5% (95% confidence interval [CI]: 74.2 to 94.4). The PCR assessment was negative for all 136 non-scrub typhus patients, indicating a specificity of 100% (95% CI: 97.3 to 100). In addition, this test helped diagnose patients with inconclusive immunofluorescence assay (IFA) results and using single blood samples. In conclusion, the real-time PCR assay proposed here is sensitive and specific in diagnosing scrub typhus. Combining PCR and serologic tests will improve the diagnosis of scrub typhus among patients presenting with acute febrile illness.KEYWORDS Orientia tsutsugamushi, real-time PCR, scrub typhus S crub typhus is a mite-borne infectious disease caused by the obligate intracellular bacterium Orientia tsutsugamushi. A characteristic feature of the disease is patients presenting nonspecific symptoms, including fever, headache, myalgia, cough, and abdominal pain, which cannot be differentiated from symptoms of other systemic infections. The presence of eschar can help diagnose this illness; however, it is found only in some patients (1). Although the clinical course of scrub typhus is usually mild and self-limiting, delaying the treatment in severe cases can lead to complications such as renal failure, myocarditis, meningoencephalitis, and death (2). Since scrub typhus is one of the most common causes of acute undifferentiated febrile illness (AUFI) in areas of endemicity (3, 4), an early, definite diagnosis is essential for providing appropriate treatment and gathering accurate epidemiological data.Scrub typhus diagnosis mainly relies on serologic tests, particularly the indirect immunofluorescence assay (IFA), whereby the illness is identified by a 4-fold increase in antibody titers in paired sera (5, 6) and/or a positive IgM titer in a single serum sample (7,8). However, these serologic tests require paired serum samples and good technician expertise, and even then they often return false negatives during the early phase of disease. In addition, reinfection by different O. tsutsugamushi strains is not uncommon in areas of endemicity and reinfected patients may sometimes

BackgroundScrub typhus (ST) is a disease caused by an obligate intracellular bacterium, Orientia tsutsugamushi, an organism that requires a BSL3 laboratory for propagation. The disease is hallmarked by an eschar at the site of the chigger bite, followed by the development of fever, malaise, myalgia, anorexia, and papulomacular rash. Indirect immunofluorescent assay (IFA) is the gold standard for scrub typhus diagnosis, however, the subjectivity of the assay, the need for a specialized laboratory and instruments has limited the wide use of the test in resource limited areas.MethodsA recombinant-protein based enzyme linked immunosorbent assay (ELISA) using the most abundant and immunodominant protein for the detection of Orientia specific antibodies in serum has been developed. The performance of the assay was evaluated using prospectively collected acute sera from 248 randomly selected patients in Thailand. The ELISA assay was evaluated using two different cutoff values.ResultsThe receiver operating characteristic (ROC) curve generated cutoff values gave slightly better consistency with diagnosis of ST than those cutoff values established by averaging ELISA optical density of known negatives at 99% confidence interval. Both cutoff values provided similar statistical parameters when compared with the diagnosis of ST, indicating the validity of both calculations to derive cutoff values. These results suggest that both IgG and IgM ELISA performed well to accurately diagnose scrub typhus cases in endemic areas using only acute serum samples.ConclusionsWe have successfully developed an ELISA assay for the detection of Orientia-specific antibodies in serum that could provide effective screening of acute sera under clinical setup and it is also a useful assay to estimate seroprevalence in various endemic areas.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-017-2512-8) contains supplementary material, which is available to authorized users.

BackgroundHIV drug resistance (HIVDR) is the major cause of treatment failure after scaling up of antiretroviral therapy (ART). HIVDR testing prior to ART initiation is not routinely performed in resource-limited settings. We aimed to assess the prevalence of primary HIVDR by short reverse transcriptase (RT) genotypic resistance assay and evaluate of the impact of the mutations on the treatment outcomes.MethodsA prospective cohort study was conducted in treatment-naïve HIV-infected patients. Fourteen major mutations of codon 99–191 on the RT gene were selected (K103N, V106A/M, V108I, Q151M, Y181C/I, M184V/I, Y188C/L/H, and G190S/A) at a cost of testing of 35 USD. The association between the presence of primary HIVDR and undetectable HIV RNA (<50 copies/mL) after 6 months of ART was determined.ResultsA total of 265 HIV-infected patients were included, with a median age of 35.2 (range, 16.8–75.2) years; 62.6% were males. The median (interquartile range) CD4 cell count at ART initiation was 216 (77–381) cells/mm3. The overall prevalence of primary HIVDR was 7.9%. The prevalence of each HIVDR mutation were K103N 6.0%, V106I 1.1%, V108I 0.4%, Y181C 2.3%, Y181I 0.7%, Y181V 0.4%, M184V 3.0%, M184I 1.5%, and G190A 2.3%. No associated factor of having primary HIVDR was determined. By multiple stepwise logistic regression, factors associated with undetectable HIV RNA after 6 months of ART were: having M184V/I (odds ratio [OR] 0.11; 95% confidence interval [CI] 0.02–0.62, p = 0.013), condom use (OR 2.38; 95% CI 1.12–5.06, p = 0.024), and adherence per 5% increase (OR 1.16; 95% CI 1.00–1.35, p = 0.044).ConclusionsThe prevalence of primary HIVDR is approximately 8%; it is associated with detectable HIV RNA at 6 months after ART initiation. Routine “short RT” genotypic resistance assay should be considered in resource-limited settings to maximize treatment outcome.