Febrile illness in Malaysia--an analysis of 1,629 hospitalized patients

From fever to action: diagnosis, treatment, and prevention of acute undifferentiated febrile illnesses

Acute Undifferentiated Febrile Illness (AUFI) presents a clinical challenge, often characterized by sudden fever, non-specific symptoms, and potential life-threatening implications. This review highlights the global prevalence, types, challenges, and implications of AUFI, especially in tropical and subtropical regions where infectious diseases thrive. It delves into the difficulties in diagnosis, prevalence rates, regional variations, and potential causes, ranging from bacterial and viral infections to zoonotic diseases. Furthermore, it explores treatment strategies, preventive measures, and the critical role of the One Health approach in addressing AUFI. The paper also addresses the emerging zoonotic risks and ongoing outbreaks, including COVID-19, Rickettsia spp., and other novel pathogens, emphasizing their impact on AUFI diagnosis and management. Challenges in resource-limited settings are analyzed, highlighting the need for bolstered healthcare infrastructure, enhanced diagnostics, and collaborative One Health strategies. Amidst the complexity of emerging zoonotic threats, this review underscores the urgency for a multifaceted approach to mitigate the growing burden of AUFI, ensuring early diagnosis, appropriate treatment, and effective prevention strategies.

Scrub typhus and antibiotic-resistant Orientia tsutsugamushi

Introduction: Scrub typhus is one of the most underdiagnosed and under-reported febrile illnesses requiring hospitalization, mainly occurring in Southeast and East Asia and the Pacific Islands, in an area referred to as the 'Tsutsugamushi Triangle.' Scrub typhus is a zoonotic rickettsial disease that is transmitted to humans by trombiculid mites.Areas covered: A MEDLINE/PubMed search of the available literature was performed to describe the role of antibiotic-resistant scrub typhus in therapy failure.Expert opinion: Scrub typhus is characterized by an eschar that may appear 2-3 days before sudden-onset fever with chills, headache, backache, myalgia, profuse sweating, vomiting, and enlarged lymph nodes. A macular or maculopapular skin rash can develop within 3-8 days after the onset of fever. Various antibiotics, such as chloramphenicol, tetracycline, doxycycline, macrolides, quinolones, and rifampicin, have been used to treat scrub typhus. Resistance to tetracycline has been proposed to underlie delayed clinical improvement since 1996, but recent reports have questioned the existence of doxycycline resistance. Nevertheless, the existence and importance of antibiotic-resistant scrub typhus remain uncertain and require further study.

Scrub typhus: a reemerging infection

PURPOSE OF REVIEW

Scrub typhus, caused by Orientia tsutsugamushi, is a widely neglected disease which is gaining global momentum because of its resurgence patterns. The disease is now being reported in newer regions as well as areas previously endemic areas. In this review, we aim to comprehensively review the data available to assist physicians in making an accurate diagnosis and appropriate management of the disease.

RECENT FINDINGS

Several diagnostic tests have been developed for confirming scrub typhus. However, there is lack of clarity on which tests are most appropriate in a given clinical scenario. A recent study has demonstrated that in early disease (<7 days) when serological tests remain negative, the quantitative polymerase chain reaction is the most sensitive test. Among the serological tests, both IgM enzyme-linked immunosorbent assay as well as rapid diagnostic tests revealed excellent sensitivities and specificities.

SUMMARY

With the reemergence of scrub typhus, a high degree of clinical suspicion is required to appropriately diagnose this disease which presents as an acute febrile illness. It can progress to develop various complications leading to multi-organ dysfunction syndrome. Mild illness responds well to antibiotic treatment with doxycycline and azithromycin. Further studies are required to determine the most optimal therapy in severe scrub typhus infections and superiority of one drug over the other.

Scrub Typhus and the Misconception of Doxycycline Resistance

Scrub typhus, a neglected infectious disease caused by the obligate intracellular bacterium Orientia tsutsugamushi, is a major cause of fever across the Asia Pacific region with more than a billion people at risk. Treatment with antibiotics such as doxycycline or chloramphenicol is effective for the majority of patients. In the 1990s, reports from northern Thailand raised a troubling observation; some scrub typhus patients responded poorly to doxycycline, which investigators attributed to doxycycline resistance. Despite the controversial nature of these reports, independent verification was neglected, with subsequent studies speculating on the role of doxycycline resistance in contributing to failure of treatment or prophylaxis. In this review, we have outlined the evidence for drug-resistant Orientia tsutsugamushi, assessed the evidence for doxycycline resistance, and highlight more recent findings unsupportive of doxycycline resistance. We conclude that doxycycline resistance is a misconception, with treatment outcome likely to be determined by other bacterial, host, and pharmacological factors.

Prompt defervescence after initiation of treatment for rickettsial infections - time to dispense with the dogma?

INTRODUCTION

Clinicians are commonly taught that if patients with suspected rickettsial disease have continuing fever after 48 hours of anti-rickettsial therapy, an alternative diagnosis is likely.

METHODS

This retrospective study of patients hospitalised with scrub typhus and Queensland tick typhus (QTT) in tropical Australia, examined the time to defervescence after initiation of the patients' anti-rickettsial therapy. It also identified factors associated with delayed defervescence (time to defervescence >48 hours after antibiotic commencement).

RESULTS

Of the 58 patients, 32 (56%) had delayed defervescence. The median (interquartile range (IQR)) age of patients with delayed defervescence was 52 (37-62) versus 40 (28-53) years in those who defervesced within 48 hours (p = 0.05). Patients with delayed defervescence were more likely to require Intensive Care Unit (ICU) admission than those who defervesced within 48 hours (12/32 (38%) versus 3/26 (12%), p = 0.02). Even among patients not requiring ICU care, patients with delayed defervescence required a longer hospitalisation than that those who defervesced within 48 hours (median (IQR): 6 (3-8) versus 3 (2-5) days, p = 0.006).

CONCLUSIONS

A significant proportion of patients with confirmed scrub typhus and QTT will remain febrile for >48 hours after appropriate anti-rickettsial therapy. Delayed defervescence is more common in patients with severe disease.

Rickettsioses as Major Etiologies of Unrecognized Acute Febrile Illness, Sabah, East Malaysia

Orientia tsutsugamushi, spotted fever group rickettsioses, and typhus group rickettsioses (TGR) are reemerging causes of acute febrile illness (AFI) in Southeast Asia. To further delineate extent, we enrolled patients >4 weeks of age with nonmalarial AFI in Sabah, Malaysia, during 2013-2015. We confirmed rickettsioses (past or acute, IgG titer >160) in 126/354 (36%) patients. We confirmed acute rickettsioses (paired 4-fold IgG titer rise to >160) in 38/145 (26%) patients: 23 O. tsutsugamushi, 9 spotted fever group, 4 TGR, 1 O. tsutsugamushi/spotted fever group, and 1 O. tsutsugamushi/TGR. PCR results were positive in 11/319 (3%) patients. Confirmed rickettsioses were more common in male adults; agricultural/plantation work and recent forest exposure were risk factors. Dizziness and acute hearing loss but not eschars were reported more often with acute rickettsioses. Only 2 patients were treated with doxycycline. Acute rickettsioses are common (>26%), underrecognized, and untreated etiologies of AFI in East Malaysia; empirical doxycycline treatment should be considered.

Underdiagnoses of Rickettsia in patients hospitalized with acute fever in Indonesia: observational study results

BACKGROUND

Reports of human rickettsial infection in Indonesia are limited. This study sought to characterize the epidemiology of human rickettsioses amongst patients hospitalized with fever at 8 tertiary hospitals in Indonesia.

METHODS

Acute and convalescent blood from 975 hospitalized non-dengue patients was tested for Rickettsia IgM and IgG by ELISA. Specimens from cases with seroconversion or increasing IgM and/or IgG titers were tested for Rickettsia IgM and IgG by IFA and Rickettsia genomes using primers for Rickettsia (R.) sp, R. typhi, and Orientia tsutsugamushi. Testing was performed retrospectively on stored specimens; results did not inform patient management.

RESULTS

R. typhi, R. rickettsii, and O. tsutsugamushi IgG antibodies were identified in 269/872 (30.8%), 36/634 (5.7%), and 19/504 (3.8%) of samples, respectively. For the 103/975 (10.6%) non-dengue patients diagnosed with acute rickettsial infection, presenting symptoms included nausea (72%), headache (69%), vomiting (43%), lethargy (33%), anorexia (32%), arthralgia (30%), myalgia (28%), chills (28%), epigastric pain (28%), and rash (17%). No acute rickettsioses cases were suspected during hospitalization. Discharge diagnoses included typhoid fever (44), dengue fever (20), respiratory infections (7), leptospirosis (6), unknown fever (6), sepsis (5), hepatobiliary infections (3), UTI (3), and others (9). Fatalities occurred in 7 (6.8%) patients, mostly with co-morbidities.

CONCLUSIONS

Rickettsial infections are consistently misdiagnosed, often as leptospirosis, dengue, or Salmonella typhi infection. Clinicians should include rickettsioses in their differential diagnosis of fever to guide empiric management; laboratories should support evaluation for rickettsial etiologies; and public policy should be implemented to reduce burden of disease.

Clinical Characteristics and Outcome of Children Hospitalized With Scrub Typhus in an Area of Endemicity

BACKGROUND

Scrub typhus, caused by Orientia tsutsugamushi, is a major cause of acute febrile illness in children in the rural tropics.

METHODS

We recruited 60 febrile pediatric patients with a positive scrub typhus rapid diagnostic test result and 40 healthy controls from Chiang Rai Province in northern Thailand. Diagnosis was confirmed by the detection of (1) O. tsutsugamushi-specific DNA in blood or eschar samples with a polymerase chain reaction assay, (2) a fourfold rise in immunoglobulin M (IgM) titer to ≥1:3200 in paired plasma samples with an indirect immunofluorescence assay (IFA), or (3) a single IgM titer of ≥1:3200 in an acute plasma sample with an IFA. Demographic, clinical, and laboratory data were collected, and patients were followed up for 1 year.

RESULTS

Diagnosis was confirmed in 35 (58%) of 60 patients, and all controls tested negative for scrub typhus. Patients with confirmed scrub typhus had clinical symptoms, including fever (35 of 35 [100%]), eschar (21 of 35 [60%]), cough (21 of 35 [60%]), tachypnea (16 of 35 [46%]), lymphadenopathy (15 of 35 [43%]), and headache (14 of 35 [40%]). Only 4 (11%) of 35 patients received appropriate antibiotic treatment for scrub typhus before admission. The median fever-clearance time was 36 hours (interquartile range, 24-53 hours). Complications observed include hepatitis (9 of 35 [26%]), severe thrombocytopenia (7 of 35 [20%]), pneumonitis (5 of 35 [14%]), circulatory shock (4 of 35 [11%]), and acute respiratory distress syndrome (3 of 35 [9%]). Treatment failure, defined by failure to defervesce within 72 hours of antibiotic treatment initiation, was noted in 8 (23%) of 35 patients, and 1 (3%) of the 35 patients died. No evidence of relapse or reinfection was found.

CONCLUSION

Pediatric scrub typhus in northern Thailand is often severe and potentially fatal with delays in treatment a likely contributing factor. Additional studies to investigate the bacterial, pharmacologic, and immunologic factors related to treatment outcome along with measures to improve public awareness should be prioritized.

The estimated burden of scrub typhus in Thailand from national surveillance data (2003-2018)

BACKGROUND

Scrub typhus is a major cause of acute febrile illness in the tropics and is endemic over large areas of the Asia Pacific region. The national and global burden of scrub typhus remains unclear due to limited data and difficulties surrounding diagnosis.

METHODOLOGY/PRINCIPAL FINDINGS

Scrub typhus reporting data from 2003-2018 were collected from the Thai national disease surveillance system. Additional information including the district, sub-district and village of residence, population, geographical, meteorological and satellite imagery data were also collected for Chiangrai, the province with the highest number of reported cases from 2003-2018. From 2003-2018, 103,345 cases of scrub typhus were reported with the number of reported cases increasing substantially over the observed period. There were more men than women, with agricultural workers the main occupational group affected. The majority of cases occurred in the 15-64 year old age group (72,144/99,543, 72%). Disease burden was greatest in the northern region, accounting for 53% of the total reported cases per year (mean). In the northern region, five provinces-Chiangrai, Chiangmai, Tak, Nan and Mae Hong Son-accounted for 84% (46,927/55,872) of the total cases from the northern region or 45% (46,927/103,345) of cases nationally. The majority of cases occurred from June to November but seasonality was less marked in the southern region. In Chiangrai province, elevation, rainfall, temperature, population size, habitat complexity and diversity of land cover contributed to scrub typhus incidence.

INTERPRETATION

The burden of scrub typhus in Thailand is high with disease incidence rising significantly over the last two decades. However, disease burden is not uniform with northern provinces particularly affected. Agricultural activity along with geographical, meteorological and land cover factors are likely to contribute to disease incidence. Our report, along with existing epidemiological data, suggests that scrub typhus is the most clinically important rickettsial disease globally.

An observational prospective cohort study of the epidemiology of hospitalized patients with acute febrile illness in Indonesia

BACKGROUND

The epidemiology of acute febrile illness, a common cause of hospitalization in Indonesia, has not been systematically studied.

METHODOLOGY/PRINCIPAL FINDINGS

This prospective observational study enrolled febrile patients (temperature ≥38°C) aged ≥1 year from July 2013 until June 2016 at eight government referral teaching hospitals in seven provincial capitals in Indonesia. Patients were managed according to the hospital standard-of-care (SOC), and blood samples were drawn for molecular and serological assays. Clinical data, laboratory results, and specimens for additional tests were collected at enrollment, days 14-28, and at three months. Regular follow-up visits were then scheduled for every three months either until symptoms resolved or until one year. In total, this study included 1,486 adult and pediatric patients presenting with multi-organ (768, 51.7%), gastrointestinal (497, 33.0%), respiratory (114, 7.7%), constitutional (62, 4.2%), skin and soft-tissue (24, 1.6%), central nervous system (17, 1.1%), or genitourinary (4, 0.3%) manifestations. Microbiological diagnoses were found in 1,003/1,486 (67.5%) participants, of which 351/1,003 (35.0%) were not diagnosed during hospitalization using SOC diagnostic tests. Missed diagnoses included all cases caused by Rickettsia spp., chikungunya, influenza, and Seoul virus. The most common etiologic agents identified were dengue virus (467, 46.6%), Salmonella spp. (103, 10.3%), and Rickettsia spp. (103, 10.3%). The overall mortality was 89 (5.9%).

CONCLUSIONS/SIGNIFICANCE

Febrile illness in Indonesia has various microbiologic etiologies and substantial overall mortality. Diagnostic limitations and lack of epidemiologic data resulted in potentially treatable, and at times fatal, diseases being missed.

Case Fatality Rate of Enteric Fever in Endemic Countries: A Systematic Review and Meta-analysis

Enteric fever is a febrile illness, occurring mostly in Asia and Africa, which can present as a severe and possibly fatal disease. Currently, a case fatality rate (CFR) of 1% is assumed when evaluating the global burden of enteric fever. Until now, no meta-analysis has been conducted to summarize mortality from enteric fever. Therefore, we conducted a systematic review and meta-analysis to aggregate all available evidence. We estimated an overall CFR of 2.49% (95% confidence interval, 1.65%-3.75%; n = 44), and a CFR in hospitalized patients of 4.45% (2.85%-6.88%; n = 21 of 44). There was considerably heterogeneity in estimates of the CFR from individual studies. Neither age nor antimicrobial resistance were significant prognostic factors, but limited data were available for these analyses. The combined estimate of the CFR for enteric fever is higher than previously estimated, and the evaluation of prognostic factors, including antimicrobial resistance, urgently requires more data.

Causes of acute undifferentiated fever and the utility of biomarkers in Chiangrai, northern Thailand

BACKGROUND

Tropical infectious diseases like dengue, scrub typhus, murine typhus, leptospirosis, and enteric fever continue to contribute substantially to the febrile disease burden throughout Southeast Asia while malaria is declining. Recently, there has been increasing focus on biomarkers (i.e. C-reactive protein (CRP) and procalcitonin) in delineating bacterial from viral infections.

METHODOLOGY/PRINCIPAL FINDINGS

A prospective observational study was performed to investigate the causes of acute undifferentiated fever (AUF) in adults admitted to Chiangrai Prachanukroh hospital, northern Thailand, which included an evaluation of CRP and procalcitonin as diagnostic tools. In total, 200 patients with AUF were recruited. Scrub typhus was the leading bacterial cause of AUF (45/200, 22.5%) followed by leptospirosis (15/200, 7.5%) and murine typhus (7/200, 3.5%), while dengue was the leading viral cause (23/200, 11.5%). Bloodstream infections contributed to 7/200 (3.5%) of the study cohort. There were 9 deaths during this study (4.5%): 3 cases of scrub typhus, 2 with septicaemia (Talaromyces marneffei and Haemophilus influenzae), and 4 of unknown aetiologies. Rickettsioses, leptospirosis and culture-attributed bacterial infections, received a combination of 3rd generation cephalosporin plus a rickettsia-active drug in 53%, 73% and 67% of cases, respectively. Low CRP and white blood count were significant predictors of a viral infection (mainly dengue) while the presence of an eschar and elevated aspartate aminotransferase and alkaline phosphatase were important predictors of scrub typhus.

INTERPRETATION

Scrub typhus and dengue are the leading causes of AUF in Chiangrai, Thailand. Eschar, white blood count and CRP were beneficial in differentiating between bacterial and viral infections in this study. CRP outperformed procalcitonin although cut-offs for positivity require further assessment. The study provides evidence that accurate, pathogen-specific rapid diagnostic tests coupled with biomarker point-of-care tests such as CRP can inform the correct use of antibiotics and improve antimicrobial stewardship in this setting.

The Historical Case for and the Future Study of Antibiotic-Resistant Scrub Typhus

Scrub typhus is an acute, and sometimes fatal, human febrile illness, typically successfully treated using chloramphenicol or one of the tetracyclines. Over the past several years, descriptions of strains of Orientia tsutsugamushi with reduced susceptibility to antibiotics have appeared. Because case-fatality ratios approached 50% during the pre-antibiotic era, antibiotic-resistant scrub typhus is concerning. Herein, we review the data on resistant scrub typhus, describe how the theoretical existence of such resistance is affected by interpretation of treatment outcomes, and propose a plan to further identify whether true drug resistance is present and how to deal with drug resistance if it has evolved. Limited resistance is not unambiguous, if present, and antibiotic resistance in scrub typhus is not a dichotomous trait. Rather, evidence of resistance shows a continuous gradation of increasing resistance. The availability of genomes from isolates of O. tsutsugamushi allows the search for loci that might contribute to antibiotic resistance. At least eighteen such loci occur in all genomes of O. tsutsugamushi examined. One gene (gyrA) occurs as a quinolone-resistant form in the genome of all isolates of O. tsutsugamushi. At least 13 other genes that are present in some members of the genus Rickettsia do not occur within O. tsutsugamushi. Even though reports of scrub typhus not responding appropriately to chloramphenicol or a tetracycline treatment have been in the literature for approximately 23 years, the existence and importance of antibiotic-resistant scrub typhus remains uncertain.

Serial Changes in Complete Blood Counts in Patients with Leptospirosis: Our Experience

INTRODUCTION

Leptospirosis is an infectious disease caused by Leptospira interrogans. It is endemic in many parts of the world. The symptoms vary between milder forms to severe type with organ dysfunction. The disease presents with diagnostic challenge as it clinically mimics acute febrile illness due to other causes.

AIM

To study serial changes in complete blood counts in patients with leptospirosis.

MATERIALS AND METHODS

A retrospectively collected data was prospectively studied for clinical and laboratory data of leptospirosis patients proven by raised IgM titres by ELISA on day 2 (counted from day of admission of patient to hospital) of unexplained fever. The changes in complete blood counts from admission upto the discharge of the patient were studied. SPSS version 13 (SPSS Inc. Chicago) was used for data analysis. The collected data was analysed using frequency, percentage, mean, median, standard deviation and Mann-Whitney test. A p-value less than 0.05 were considered significant.

RESULTS

Mean haemoglobin concentration showed a progressive decline (<12.5 gm/dl) from day 1 to day 7 in both mild and severe disease. Platelet counts were significantly low (p=0.002), (<1,50,000 cells/mm³) in severe disease and showed a declining trend as compared to mild disease. Total leukocyte counts were significantly higher (p=0.001), (>11,000 cells/m³) in patients with severe disease from day 4 to day 5 of the illness.

CONCLUSION

Complete blood count is a routine test done in the monitoring of patients with leptospirosis. Declining haemoglobin, marked thrombocytopenia and a normal to high total leukocyte count will help in early detection of severe disease and thus preventing mortality by timely management.

Challenges in the Etiology and Diagnosis of Acute Febrile Illness in Children in Low- and Middle-Income Countries

Acute febrile illness is a common cause of hospital admission, and its associated infectious causes contribute to substantial morbidity and death among children worldwide, especially in low- and middle-income countries. Declining transmission of malaria in many regions, combined with the increasing use of rapid diagnostic tests for malaria, has led to the increasing recognition of leptospirosis, rickettsioses, respiratory viruses, and arboviruses as etiologic agents of fevers. However, clinical discrimination between these etiologies can be difficult. Overtreatment with antimalarial drugs is common, even in the setting of a negative test result, as is overtreatment with empiric antibacterial drugs. Viral etiologies remain underrecognized and poorly investigated. More-sensitive diagnostics have led to additional dilemmas in discriminating whether a positive test result reflects a causative pathogen. Here, we review and summarize the current epidemiology and focus particularly on children and the challenges for future research.

The Epidemiology, Virology and Clinical Findings of Dengue Virus Infections in a Cohort of Indonesian Adults in Western Java

BACKGROUND

Dengue has emerged as one of the most important infectious diseases in the last five decades. Evidence indicates the expansion of dengue virus endemic areas and consequently the exponential increase of dengue virus infections across the subtropics. The clinical manifestations of dengue virus infection include sudden fever, rash, headache, myalgia and in more serious cases, spontaneous bleeding. These manifestations occur in children as well as in adults. Defining the epidemiology of dengue in a given area is critical to understanding the disease and devising effective public health strategies.

METHODOLOGY/PRINCIPAL FINDINGS

Here, we report the results from a prospective cohort study of 4380 adults in West Java, Indonesia, from 2000-2004 and 2006-2009. A total of 2167 febrile episodes were documented and dengue virus infections were confirmed by RT-PCR or serology in 268 cases (12.4%). The proportion ranged from 7.6 to 41.8% each year. The overall incidence rate of symptomatic dengue virus infections was 17.3 cases/1,000 person years and between September 2006 and April 2008 asymptomatic infections were 2.6 times more frequent than symptomatic infections. According to the 1997 WHO classification guidelines, there were 210 dengue fever cases, 53 dengue hemorrhagic fever cases (including one dengue shock syndrome case) and five unclassified cases. Evidence for sequential dengue virus infections was seen in six subjects. All four dengue virus serotypes circulated most years. Inapparent dengue virus infections were predominantly associated with DENV-4 infections.

CONCLUSIONS/SIGNIFICANCE

Dengue virus was responsible for a significant percentage of febrile illnesses in an adult population in West Java, Indonesia, and this percentage varied from year to year. The observed incidence rate during the study period was 43 times higher than the reported national or provincial rates during the same time period. A wide range of clinical severity was observed with most infections resulting in asymptomatic disease. The circulation of all four serotypes of dengue virus was observed in most years of the study.

Ectoparasites of murids in peninsular Malaysia and their associated diseases

A considerable number of rat-borne ectoparasite studies have been conducted since the early 1930s in the Malayan Peninsula (now known as peninsular Malaysia). The majority of studies were field surveys and collections of specimens across the region, and were conducted primarily to catalogue the ectoparasite host distribution and discover novel species. This has generated a signification amount of information, particularly on the diversity and host distribution; other aspects such as morphology, host distribution and medical significance have also been investigated. Amongst the four main groups (mites, fleas, ticks, lice), rat-borne mites have received the most attention with a particular emphasis on chiggers, due to their medical importance. More recent studies have examined the distribution of ectoparasites in rats from different habitat type simplicating a high prevalence of zoonotic species infesting rat populations. Despite being capable of transmitting dangerous pathogens to human, the health risks of rat-borne ectoparasites appear to be small with no serious outbreaks of diseases recorded. Although an extensive number of works have been published, there remain gaps in knowledge that need to be addressed, such as, the distribution of under studied ectoparasite groups (listrophorids and myobiids), determining factors influencing infestation, and understanding changes to the population distribution over time.

A Study of Etiological Pattern in an Epidemic of Acute Febrile Illness during Monsoon in a Tertiary Health Care Institute of Uttarakhand, India

BACKGROUND

Many parts of India are endemic for the dengue, malaria, typhoid and scrub typhus infections. The relative contribution of these illnesses in an outbreak of acute febrile illness is not known in this region.

OBJECTIVE

The present study was conducted to find out the etiological pattern in an epidemic of acute febrile illness in Uttarakhand during the monsoon period. The study also focuses on concurrent infections and tries to find out the mortality outcomes.

MATERIALS AND METHODS

A retrospective study of four months was conducted on 1141 patients who presented with fever, and were suspected to have dengue, malaria, typhoid or scrub typhus. Patients of 12-years of age or above were included in the study. Serological tests for dengue, malaria, typhoid and scrub typhus were performed. Slides for malaria parasite were examined. In case of enteric fever only culture positive cases were included in the study.

RESULT

Among the 1141 febrile patients dengue was detected in 812(71.2 %), malaria in 146(12.8%), typhoid in 92(8.1%) and scrub typhus in 69(6.0%) cases. Mixed infection was noted in 22(1.9%).

CONCLUSION

Maximum (71.2 %) cases of fever were caused by dengue but significant number (32.3%) of patients suffered from malaria typhoid and scrub typhus. Many (1.9%) suffered from concurrent and multiple infections.

Antibody prevalence and factors associated with exposure to Orientia tsutsugamushi in different aboriginal subgroups in West Malaysia

Background

Limited data is available on the current status of scrub typhus infection in the aboriginal population in Malaysia. This study was aimed to provide recent data on the degree of exposure of 280 individuals from seven aboriginal subgroups to Orientia tsutsugamushi (causative agent of scrub typhus) in West Malaysia. The environment, socioeconomic and behavioural risk factors associated with the disease were also investigated.

Methods/Findings

The antibody prevalence to O. tsutsugamushi ranged from 0 to 36.4% in seven subgroups, with high prevalence rates noted in subgroups involved in agricultural activity and the lowest prevalence rates noted in subgroups whose main occupations were associated to fishing. Univariate analysis indicated populations with age above 18 years (OR = 1.15, 95% CI = 1.02–1.30, P = 0.015), working (OR = 1.99, 95% CI = 1.01–3.92, P = 0.044), working at agriculture area (OR = 1.18, 95% CI = 0.98–1.42, P = 0.031), receiving household income less than US$ 166.7 (RM500) per month (OR = 2.43, 95% CI = 1.16–5.11, P = 0.016) and having close contact with animal pets (OR = 4.06, 95% CI = 1.20–13.76, P = 0.016) are significantly associated with exposure to O. tsutsugamushi. Multivariate analysis confirms that participants who are above 18 years old, receiving household income less than US$ 166.7 (RM500) per month and having close contact with animal pets are 3.6 times (95% CI = 1.81–7.03, P<0.001), 1.3 times (95% CI = 1.14–1.64, P = 0.002) and 1.2 times (95% CI = 1.05–1.06, P = 0.006) more likely to have exposure to O. tsutsugamushi, respectively.

Conclusion

The present study indicates that scrub typhus is still an important disease in the aboriginal population in Malaysia. Awareness about the disease and education on the preventive measures are important in reducing the risk of acquiring scrub typhus in the population studied.

Scrub typhus has been recognized as a public health problem in the rural areas of Southeast Asia. The aboriginal population, one of the most impoverished groups in the Malaysia, may be exposed to the bite of Leptotrombidium mites (vector for scrub typhus) due to their involvement in the agricultural activities, living environment and personal habits. A serosurvey was conducted for seven aboriginal subgroups to determine antibody prevalence to O. tsutsugamushi, the causative agent of scrub typhus and to identify factors associated with scrub typhus. The findings in this study confirmed high antibody prevalence to O. tsutsugamushi in aboriginal subgroups who engaged in agricultural activity. Multivariate analysis showed that individuals who are above 18 years old, receiving household income less than US$ 166.7 (RM500) per month and having close contact with animal pets have higher exposure rates to scrub typhus. Institution of appropriate preventive measures is important in reducing the risk of acquiring scrub typhus in the population studied.

Unsuspected rickettsioses among patients with acute febrile illness, Sri Lanka, 2007

We studied rickettsioses in southern Sri Lanka. Of 883 febrile patients with paired serum samples, 156 (17.7%) had acute rickettsioses; rickettsioses were unsuspected at presentation. Additionally, 342 (38.7%) had exposure to spotted fever and/or typhus group rickettsioses and 121 (13.7%) scrub typhus. Increased awareness of rickettsioses and better tests are needed.

Contrasting spatial distribution and risk factors for past infection with scrub typhus and murine typhus in Vientiane City, Lao PDR

BACKGROUND

The aetiological diagnostic of fevers in Laos remains difficult due to limited laboratory diagnostic facilities. However, it has recently become apparent that both scrub and murine typhus are common causes of previous undiagnosed fever. Epidemiological data suggests that scrub typhus would be more common in rural areas and murine typhus in urban areas, but there is very little recent information on factors involved in scrub and murine typhus transmission, especially where they are sympatric - as is the case in Vientiane, the capital of the Lao PDR.

METHODOLOGY AND PRINCIPAL FINDINGS

We therefore determined the frequency of IgG seropositivity against scrub typhus (Orientia tsutsugamushi) and murine typhus (Rickettsia typhi), as indices of prior exposure to these pathogens, in randomly selected adults in urban and peri-urban Vientiane City (n = 2,002, ≥35 years). Anti-scrub and murine typhus IgG were detected by ELISA assays using filter paper elutes. We validated the accuracy of ELISA of these elutes against ELISA using serum samples. The overall prevalence of scrub and murine typhus IgG antibodies was 20.3% and 20.6%, respectively. Scrub typhus seropositivity was significantly higher among adults living in the periphery (28.4%) than in the central zone (13.1%) of Vientiane. In contrast, seroprevalence of murine typhus IgG antibodies was significantly higher in the central zone (30.8%) as compared to the periphery (14.4%). In multivariate analysis, adults with a longer residence in Vientiane were at significant greater risk of past infection with murine typhus and at lower risk for scrub typhus. Those with no education, living on low incomes, living on plots of land with poor sanitary conditions, living in large households, and farmers were at higher risk of scrub typhus and those living in neighborhoods with high building density and close to markets were at greater risk for murine typhus and at lower risk of scrub typhus past infection.

CONCLUSIONS

This study underscores the intense circulation of both scrub and murine typhus in Vientiane city and underlines difference in spatial distribution and risk factors involved in the transmission of these diseases.

Leptospirosis: an emerging disease in travellers

A recent upsurge in leptospirosis in travellers has prompted the following review of the epidemiology of this infection in humans. The available data from the published literature as well as laboratory surveillance were examined to determine the possible causes of the apparent change in epidemiology.

Laboratory evaluation of aromatic essential oils from thirteen plant species as candidate repellents against Leptotrombidium chiggers (Acari: Trombiculidae), the vector of scrub typhus

Scrub typhus, a rickettsial disease transmitted by several species of Leptotrombidium chiggers (larvae), is endemic in many areas of Asia. The disease is best prevented by the use of personal protective measures, including repellents. In this study commercially produced aromatic, essential oils of 13 plant species and ethanol (control) were tested in the laboratory for repellency against host-seeking chiggers of Leptotrombidium imphalum Vercammen-Grandjean and Langston (Acari: Trombiculidae). A rapid, simple and economic in vitro test method was used by exposing the chigger for up to 5 min. Repellency was based on relative percentages of chiggers attracted to test and control substances. Four of the 13 essential oils showed promise as effective repellent against L. imphalum chiggers. Syzygium aromaticum (clove) oil exhibited 100% repellency at 5% concentration (dilution with absolute ethanol), whereas Melaleuca alternifolia (tea tree) oil exhibited 100% repellency at 40% concentration. Undiluted oils of Zingiber cassamunar (plai) and Eucalyptus globules (blue gum) exhibited 100% repellency. Of the remaining nine essential oils, only 100% Pelargonium graveolens (geranium) exhibited >50% repellency (viz. 57%). Styrax torkinensis (benzoin) oil did not exhibit any repellency. These findings show that several aromatic, essential oils of plants may be useful as chigger repellent for the prevention of scrub typhus. Syzygium aromaticum oil may be safer and more economical to prevent chigger attacks than commercially available synthetic chemicals, such as DEET that may have harmful side effects.

Part I. Analysis of data gaps pertaining to Salmonella enterica serotype Typhi infections in low and medium human development index countries, 1984-2005

There are only 10 contemporary, population-based studies of typhoid fever that evaluate disease incidence using blood culture for confirmation of cases. Reported incidence ranged from 13 to 976/100 000 persons per year. These studies are likely to have been done preferentially in high- incidence sites which makes generalization of data difficult. Only five of these studies reported mortality. Of these the median (range) mortality was 0% (0-1.8%). Since study conditions usually involved enhanced clinical management of patients and the studies were not designed to evaluate mortality as an outcome, their usefulness for generalizing case-fatality rates is uncertain. No contemporary population-based studies reported rates of complications. Hospital-based typhoid fever studies reported median (range) complication rates of 2.8% (0.6-4.9%) for intestinal perforation and case-fatality rates of 2.0% (0-14.8%). Rates of complications other than intestinal perforation were not reported in contemporary hospital-based studies. Hospital-based studies capture information on the most severe illnesses among persons who have access to health-care services limiting their generalizability. Only two studies have informed the current understanding of typhoid fever age distribution curves. Extrapolation from population-based studies suggests that most typhoid fever occurs among young children in Asia. To reduce gaps in the current understanding of typhoid fever incidence, complications, and case-fatality rate, large population-based studies using blood culture confirmation of cases are needed in representative sites, especially in low and medium human development index countries outside Asia.

Doxycycline versus azithromycin for treatment of leptospirosis and scrub typhus

Leptospirosis and scrub typhus are important causes of acute fever in Southeast Asia. Options for empirical therapy include doxycycline and azithromycin, but it is unclear whether their efficacies are equivalent. We conducted a multicenter, open, randomized controlled trial with adult patients presenting with acute fever (<15 days), without an obvious focus of infection, at four hospitals in Thailand between July 2003 and January 2005. Patients were randomly allocated to receive either a 7-day course of doxycycline or a 3-day course of azithromycin. The cure rate, fever clearance time, and adverse drug events were compared between the two study groups. A total of 296 patients were enrolled in the study. The cause of acute fever was determined for 151 patients (51%): 69 patients (23.3%) had leptospirosis; 57 patients (19.3%) had scrub typhus; 14 patients (4.7%) had murine typhus; and 11 patients (3.7%) had evidence of both leptospirosis and a rickettsial infection. The efficacy of azithromycin was not inferior to that of doxycycline for the treatment of both leptospirosis and scrub typhus, with comparable fever clearance times in the two treatment arms. Adverse events occurred more frequently in the doxycycline group than in the azithromycin group (27.6% and 10.6%, respectively; P = 0.02). In conclusion, doxycycline is an affordable and effective choice for the treatment of both leptospirosis and scrub typhus. Azithromycin was better tolerated than doxycycline but is more expensive and less readily available.

Scrub typhus serologic testing with the indirect immunofluorescence method as a diagnostic gold standard: a lack of consensus leads to a lot of confusion

A review was performed to determine the evidence base for scrub typhus indirect immunofluorescence assay (IFA) methodologies and the criteria for positive results. This review included a total of 109 publications, which comprised 123 eligible studies for analysis (14 publications included 2 substudies). There was considerable underreporting of the IFA methodology and seropositivity criteria used, with most studies using a defined cutoff titer rather than an increase in the titer in paired samples. The choice of positivity cutoff titer varied by country and purpose of the IFA test. This variation limits the comparability of seroprevalence rates between studies and, more seriously, raises questions about the appropriateness of the cutoffs for positive IFA results chosen for diagnosis of acute scrub typhus infection. We suggest that the diagnosis of scrub typhus using IFA should be based on a > or =4-fold increase in the titer in paired serum samples and should only be based on a single sample titer when there is an adequate local evidence base.

Causes of acute, undifferentiated, febrile illness in rural Thailand: results of a prospective observational study

The adult patients who, between July 2001 and June 2002, presented at any of five hospitals in Thailand with acute febrile illness in the absence of an obvious focus of infection were prospectively investigated. Blood samples were taken from all of the patients and checked for aerobic bacteria and leptospires by culture. In addition, at least two samples of serum were collected at different times (on admission and 2-4 weeks post-discharge) from each patient and tested, in serological tests, for evidence of leptospirosis, rickettsioses, dengue and influenza. The 845 patients investigated, of whom 661 were male, had a median age of 38 years and a median duration of fever, on presentation, of 3.5 days. Most (76.5%) were agricultural workers and most (68.3%) had the cause of their fever identified, as leptospirosis (36.9%), scrub typhus (19.9%), dengue infection or influenza (10.7%), murine typhus (2.8%), Rickettsia helvetica infection (1.3%), Q fever (1%), or other bacterial infection (1.2%). The serological results indicated that 103 (12.2%) and nine (1%) of the patients may have had double and triple infections, respectively. Leptospirosis and rickettsioses, especially scrub typhus, were thus found to be major causes of acute, undifferentiated fever in Thai agricultural workers.

Evaluation of nested PCR for the diagnosis of scrub typhus among patients with acute pyrexia of unknown origin

A nested PCR technique was performed to detect a specific 483 bp DNA fragment of Orientia tsutsugamushi, the aetiological agent of scrub typhus, in 53 blood samples from 36 patients with acute pyrexia of unknown origin in southern Thailand. The specific primers could amplify the specific DNA from all 10 prototype strains of O. tsutsugamushi and all nine seropositive patients and three seronegative patients, while no DNA amplification was obtained with DNAs from other rickettsiae or from healthy persons or from patients with murine typhus. The specific PCR product was detectable in the blood for as long as 22 days after the onset of disease in patients without specific treatment and 27 days after receiving a single dose of doxycycline. Thus, nested PCR may be more sensitive than the serological test for diagnosis of scrub typhus and prolonged persistence of O. tsutsugamushi DNA in patients' blood was demonstrated despite clinical recovery of the patients.

Epidemiologic, clinical and laboratory features of scrub typhus in thirty Thai children

BACKGROUND

Scrub typhus, a potentially fatal rickettsial infection, is common in Asia. Although serologic surveys suggested that as many as one-fourth of cases of scrub typhus might be in children, very few reports of childhood scrub typhus are available in the medical literature.

OBJECTIVES

To document the clinical, laboratory and epidemiologic characteristics of pediatric patients with scrub typhus.

METHODS

From January 1, 2000 to December 31, 2001, all pediatric patients at Chiang Mai University Hospital who had obscure fever for >5 days were tested for indirect immunofluorescent antibody (IFA) against Orientia tsutsugamushi, the causative organism of scrub typhus. Scrub typhus was diagnosed on the basis of either a single IFA titer against O. tsutsugamushi > or =1/400 or a 4-fold or greater rise in IFA titer to at least 1/200.

RESULTS

Thirty children with scrub typhus were enrolled. Most were diagnosed during the rainy months of June to November. Common physical signs included lymphadenopathy (93%), hepatomegaly (73%), eschar (68%), conjunctival hyperemia (33%), maculopapular rash (30%) and splenomegaly (23%). Eleven patients had interstitial pneumonitis and 1 patient had meningitis. All patients responded well to doxycycline or chloramphenicol. The average interval to defervescence after treatment was 29 h (range, 6 to 72).

CONCLUSIONS

Clinical and epidemiologic features of 30 pediatric patients with scrub typhus are reported in a prospective study. The presence of eschar was helpful in making the diagnosis. Complications included pneumonitis and meningitis. All cases responded well to treatment with antibiotic.

The past and present threat of rickettsial diseases to military medicine and international public health

Morbidity and mortality caused by rickettsioses have had a major influence on military activities and public health for >2000 years. The threat posed by the rickettsioses is reviewed, focusing on the impact and epidemiology of those that have adversely influenced wartime operations and the current challenges posed by these diseases. With their uneven worldwide distribution, the discovery of drug-refractory strains of Orientia tsutsugamushi, the increased threat of their use in acts of bioterrorism, frequent deployment of troops to regions of endemicity, and exposures due to increased humanitarian missions, these diseases continue to be a threat to military personnel in the field. Effective strategies to reduce the impact of these diseases include development of effective vaccines, enhanced surveillance, and development of new safe, effective, and odorless repellants. The continuation of a proven, highly productive military infectious disease research program is essential for providing solutions to these daunting tasks.

Efficiency of Leptotrombidium chiggers (Acari: Trombiculidae) at transmitting Orientia tsutsugamushi to laboratory mice

Thirteen different laboratory colonies of Leptotrombidim chiggers [L. chiangraiensis Tanskul & Linthicum, L. deliense Walch and L. imphalum (Vercammen-Grandjean &Langston)] were evaluated for their ability to transmit Orientia tsutsugamushi (Hyashi) to mice. Of 4,372 transmission attempts using individual chiggers from all 13 colonies, 75% (n = 3,275) successfully infected mice. Transmission rates for the individual chigger colonies ranged from 7 to 80%. Increasing the number of chiggers that fed on a given mouse generally increased transmission rates. Transmission of O. tsutsugamushi to mice by different generations (F1-F11) of certain chigger colonies was stable; however, transmission rates varied greatly in other colonies. Transmission rates (both vertical and horizontal) of several L. changraiensis colonies and the L. deliense colony were the highest, suggesting that these colonies may be useful for the development of a chigger-challenge model that can be used to evaluate the efficacy of candidate scrub typhus vaccines or therapeutic agents in laboratory mice.

Antibodies to Orientia tsutsugamushi, Rickettsia typhi and spotted fever group rickettsiae among febrile patients in rural areas of Malaysia

A serosurvey was conducted in 1995-97 among 1596 febrile patients from 8 health centres in Malaysia for antibodies against Orientia tsutsugamushi (OT), Rickettsia typhi (RT) and TT118 spotted fever group rickettsiae (SFGR) by using an indirect immunoperoxidase assay. A total of 51.4% patients had antibody against at least 1 of those rickettsiae. Antibody to SFGR was most prevalent (42.5%), followed by RT (28.1%) and OT (24.9%). The seroprevalences of antibodies to SFGR, RT or OT alone were 12.4, 3.6 and 4.3%, respectively. Antibodies against more than 1 species of rickettsiae were presence in 31.1% of the patients, suggesting the possibility of co-infection, previous exposures or serological cross-reactivities. Seroprevalence of the various rickettsiae varied according to locality, with SFGR antibodies being the most prevalent in most areas. There was no significant association of prevalence of rickettsial antibody with gender. The seroprevalence of OT, SFGR and RT increased with patient age but an increase of antibody titre with age was not significant. Those working in the agricultural sectors had significantly higher seroprevalence of OT, SFGR and RT than those not related with agricultural activities. Scrub typhus remains a public health problem with an estimated annual attack rate of 18.5%. Tick typhus and murine typhus as shown in this serosurvey appear much more widespread than scrub typhus in this country.

Comparative evaluation of four serodiagnostic tests for scrub typhus in Thailand

The commercial dot-blot enzyme-linked immunosorbent assay Dip-S-Ticks dipstick test was compared with the indirect immunoperoxidase (IIP) and Weil-Felix (WF) tests for the diagnosis of scrub typhus, using the indirect immunofluorescent antibody test (IFA) as the reference standard. With a panel of 117 positive and 75 negative sera, the dipstick test was 94% sensitive and 98.7% specific at a cut-off value of one or more positive dots. The IIP was 90.6% sensitive and 100% specific at a cut-off titre of 1:400, and was more sensitive than the IFA with acute sera (79.6% vs. 68.5% at a titre > or = 1:400). All 3 were superior to the WF, which lacked sensitivity. The dipstick assay was easy to perform and did not require sophisticated electrical equipment, and the results were available within one hour. It is therefore suitable for use in rural Thailand, where scrub typhus is common.

Tropical respiratory medicine. 4. Acute tropical infections and the lung

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Epitope mapping of the Sta58 major outer membrane protein of Rickettsia tsutsugamushi

Binding studies of 160 overlapping, synthetic octapeptides from the hydrophilic regions of the Sta58 major outer membrane protein of Rickettsia tsutsugamushi with sera from patients with scrub typhus revealed 15 immunodominant peptides which are recognized by all the sera tested. Further analysis of the specificity of peptide binding with five of these peptides indicated that the peptides showed significantly stronger binding to scrub typhus patients' sera than they did to sera from patients with other febrile illnesses common in the region, i.e., malaria, dengue fever, typhoid fever, and leptospirosis. The main antibody class binding to these peptides appears to be immunoglobulin M, and there appears to be little correlation between reactivity with peptides and antibody titers measured by the indirect immunoperoxidase test.

Epidemiology of rickettsial diseases

Rickettsial diseases have a diversity of epidemiologic characteristics reflective of the variety of ecologic situations in which the obligate intracellular bacteria are transmitted to humans. For the spotted fever group (SFG) rickettsiae, Rickettsia typhi, R. tsutsugamushi, Coxiella burnetii, and the human ehrlichial agent, humans are a dead-end host who plays no role in the maintenance of the organism in nature. All rickettsioses exist as zoonoses. Moreover, all rickettsiae are found in infected arthopods, which generally serve as the natural hosts and can transmit the infection to the next generation of ticks, mites, chiggers, or fleas. From our anthropocentric viewpoint, Q fever aerosol infection from parturient animals and Brill-Zinsser disease ignited epidemics of louse-borne epidemic typhus are exceptions. However, silent cycles of C. burnetii in ticks and R. prowazekii in the flying squirrel flea may have maintained these agents in transovarial or enzootic cycles for eons before humans and their domestic animals arrived on the scene. Thus, the epidemiology of rickettsial diseases must be recognized as an unfortunate aberration of the rickettsial economy. Several excellent reviews of rickettsial ecology contain a wealth of useful information.

Detection of Rickettsia tsutsugamushi by gene amplification using polymerase chain reaction techniques

Scrub typhus is commonly undiagnosed in endemic areas due, in part, to dependence on retrospective serodiagnosis. Since the etiologic agent, R. tsutsugamushi, will not grow in cell-free systems, a rapid direct-agent detection system such as provided by polymerase chain reaction (PCR) methodology is needed. Genes coding for the variable 56-kDa antigen of R. tsutsugamushi were amplified through 35 cycles using 20-mer oligonucleotide primers and Taq polymerase. Amplification of 1-ng samples of DNA extracted from purified prototype R. tsutsugamushi Karp, Gilliam, and Kato strains was detected by direct visual inspection of the electrophoresed, ethidium bromide-stained, specific bands. Specificity of the PCR was shown when PCR amplification of various non-scrub typhus rickettsial DNAs was unsuccessful. R. tsutsugamushi DNA extracted from the blood of infected mice could be PCR amplified and the 1477-base pair product detected by either direct visualization or by specific hybridization with amplified non-radioactive digoxigenin-11-dUTP-labeled Karp 56-kDa DNA probe.

Fever in hospitalized patients. With special reference to the medical service

Fever (oral temperature of 38 degrees C or more on two or more consecutive days) during the hospital stay of 4,065 patients admitted to Grady Memorial Hospital during an 11-week period was studied. At least one episode of fever occurred in 1,194 patients (29 percent). Rates of fever were highest on medical and surgical services. Review of 341 episodes of fever in 302 patients on the medical service identified a single potential cause in 56 percent. Multiple factors were present in 26 percent, and no potential causes were found in 18 percent. Of 390 factors identified, 44 percent were community-acquired infections, 9 percent were nosocomial infections, 20 percent possibly involved infection, and 26 percent were noninfectious processes. Fever is a frequent finding in hospitalized patients. Both infectious and noninfectious processes play important roles. Determining the cause of fever is complicated by the multiplicity of possible causes.