Undiagnosed undifferentiated fever in Far North Queensland, Australia: a retrospective study

Complex transmission epidemiology of neglected Australian arboviruses: diverse non-human vertebrate hosts and competent arthropod invertebrate vectors

More than 75 arboviruses are indigenous to Australia, of which at least 13 are known to cause disease in humans. Alphaviruses are the most common arboviruses, notably including Ross River and Barmah Forest viruses, which contribute a significant public health and economic burden in Australia. Both can cause febrile illness with arthritic symptoms. Each circulates nationally across diverse climates and environments, and has multi-host, multi-vector dynamics. Several medically important flaviviruses also circulate in Australia. Infection with Murray Valley encephalitis or Kunjin viruses is less common but is associated with brain inflammation. Key research priorities for Australian arboviruses aim to understand clinical manifestations, develop timely diagnostics, and identify transmission cycles that permit the maintenance of arboviruses. While these can now be answered for a handful of notifiable alpha- and flaviviruses there are others for which non-human vertebrate hosts and competent arthropod invertebrate vectors are still to be identified and/or whose role in transmission is not well understood. One or more of these 'neglected' arboviruses may be the causative agent of a proportion of the many thousands of fever-related illnesses reported annually in Australia that at present remain undiagnosed. Here, what is known about enzootic cycling of viruses between arthropod vectors and mammalian and avian reservoir hosts is summarised. How and to what extent these interactions influence the epidemiology of arbovirus transmission and infection is discussed.

The Relationship Between Serum Albumin Levels and Sepsis in Patients Admitted to a Tertiary Care Center in India

Introduction Sepsis poses a significant threat in Indian hospitals, with high mortality rates and complications. This study explores the correlation between serum albumin levels and sepsis outcomes in an intensive care unit (ICU) setting. The challenges of diagnosing tropical infections further complicate sepsis management in India. Methodology A longitudinal study was conducted at Vinayaka Mission's Kirupananda Variyar Medical College and Hospital, Salem, India. Adult patients admitted between July 2020 and March 2021 with sepsis were included. Serum albumin levels, demographic data, and clinical outcomes were analyzed. The study used a convenient sampling technique with a sample size of 102 patients. Results Among the 102 patients in the ICU, 22 have expired and the mortality rate in the study was 21.6%. Hypoalbuminemia was present in 56.9% (n = 58) of the patients. The mortality rate is higher among the sepsis patients with the occurrence of hypoalbuminemia (29.3%) compared to patients without hypoalbuminemia (11.4%) and the difference in proportion between the two groups was statistically significant (p-value = 0.029). The requirement of vasopressor support is higher among sepsis patients with the occurrence of hypoalbuminemia (56.9%) compared to patients without hypoalbuminemia (27.3%). The chi-square test reveals that the difference in proportion between the two groups was statistically significant (p-value = 0.005). No substantial impact on systemic inflammatory response scores, readmission to ICU, or progression to chronic illness was observed based on albumin levels. Conclusion This study underscores the predictive value of hypoalbuminemia in sepsis outcomes. Patients with decreased albumin levels showed higher mortality rates and increased vasopressor usage. While albumin levels did not significantly influence certain parameters, hypoalbuminemia may serve as an indicator of severity and adverse prognosis in sepsis, emphasizing the need for further research and tailored interventions.

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.

Opportunities and challenges to accurate diagnosis and management of acute febrile illness in adults and adolescents: A review

Acute febrile illnesses are common reasons to seek healthcare globally. They can be caused by diverse infectious diseases which require complex diagnostics. Current clinical guidelines provide guidance on how to manage severe illness, common localizing infections like pneumonia and urinary tract infections, as well as malaria. How to manage other cases of acute febrile illness is less clear and is the focus of this review. Without an etiologic diagnosis, clinicians frequently prescribe empiric antibiotics that may be unnecessary or inadequate. We reviewed recent studies on the etiology of acute febrile illnesses in adults and adolescents that employed multiple diagnostic modalities, including rapid diagnostic tests, serologies, and polymerase chain reaction. Although studies and etiologies were heterogenous, we enumerated the causes of febrile illness in these studies. Possible improvements in clinical decision-making algorithms are discussed.

Etiologic Agents of Fever of Unknown Origin Among Patients Attending Mnazi Mmoja Hospital, Zanzibar

BACKGROUND

Fever of unknown origin (FUO) remains an important public health problem. With malaria transmission declining in some parts of Africa, the evidence suggests other infectious agents now account for most FUO. The purpose of this study was to identify the etiologic agents of FUO in a cross-section of patients at the Mnazi Mmoja hospital in Zanzibar, Tanzania.

METHODOLOGY

A multiplex TaqMan gene expression Array Card (TAC) and plates were used for detection and classification of different pathogens in blood samples obtained from patients with FUO. Logistic regression analyses was performed using pathogens detected and sociodemographic characteristics as outcome and exposure variables respectively. Odd ratios and 95% confidence interval were calculated and statistical significance was set at P < .05.

RESULT

Thirty-three different pathogens were detected in 27 patient blood samples. The following pathogens were detected in decreasing order of prevalence; Dengue virus, Plasmodium species, Rickettsia, Brucella species, Salmonella typhi, and less than 1% for each of Bartonella, Coxiella burnetii, Salmonella species, and Leptospira. Co-infections of Plasmodium with Dengue and S. typhi were also detected, including one case with three different pathogens-Plasmodium, Rickettsia and Brucella. There was no association between the etiologic agents of FUO and demographic or clinical characteristics.

CONCLUSIONS

Zoonotic and arboviral etiological agents of fever of unknown origin are present among patients at the Mnazi Mmoja hospital in Zanzibar, Tanzania. There is a need to develop a baseline of standardized diagnostic approaches particularly within the hospital setting. In areas with low malaria prevalence like Zanzibar, Dengue, Rickettsia, Coxiella burnetii, Brucellosis should be considered by clinicians in the differential diagnoses of FUO.

The Characteristics and Clinical Course of Patients with Scrub Typhus and Queensland Tick Typhus Infection Requiring Intensive Care Unit Admission: A 23-year Case Series from Queensland, Tropical Australia

Scrub typhus and Queensland tick typhus (QTT)-rickettsial infections endemic to tropical Australia-can cause life-threatening disease. This retrospective study examined the clinical course of all patients with laboratory-confirmed scrub typhus or QTT admitted to the intensive care unit (ICU) of a tertiary referral hospital in tropical Australia between 1997 and 2019. Of the 22 patients, 13 had scrub typhus and nine had QTT. The patients' median (interquartile range [IQR]) age was 50 (38-67) years; 14/22 (64%) had no comorbidity. Patients presented a median (IQR) of seven (5-10) days after symptom onset. Median (IQR) Acute Physiology and Chronic Health Evaluation II scores were 13 (9-17) for scrub typhus and 13 (10-15) for QTT cases (P = 0.61). Following hospital admission, the median (IQR) time to ICU admission was five (2-19) hours. The median (IQR, range) length of ICU stay was 4.4 (2.9-15.9, 0.8-33.8) days. Multi-organ support was required in 11/22 (50%), 5/22 (22%) required only vasopressor support, 2/22 (9%) required only invasive ventilation, and 4/22 (18%) were admitted for monitoring. Patients were ventilated using protective lung strategies, and fluid management was conservative. Standard vasopressors were used, indications for renal replacement therapy were conventional, and blood product usage was restrictive; 9/22 (41%) received corticosteroids. One patient with QTT died, and two (8%) additional patients with QTT developed purpura fulminans requiring digital amputation. Death or permanent disability occurred in 3/9 (33%) QTT and 0/13 scrub typhus cases (P = 0.055). Queensland tick typhus and scrub typhus can cause multi-organ failure requiring ICU care in otherwise well individuals. Queensland tick typhus appears to have a more severe clinical phenotype than previously believed.

Neglected Australian Arboviruses Associated With Undifferentiated Febrile Illnesses

Infections with commonly occurring Australian arthropod-borne arboviruses such as Ross River virus (RRV) and Barmah Forest virus (BFV) are diagnosed routinely by pathology laboratories in Australia. Others, such as Murray Valley encephalitis (MVEV) and Kunjin (KUNV) virus infections may be diagnosed by specialist reference laboratories. Although Alfuy (ALFV), Edge Hill (EHV), Kokobera (KOKV), Sindbis (SINV), and Stratford (STRV) viruses are known to infect humans in Australia, all are considered 'neglected.' The aetiologies of approximately half of all cases of undifferentiated febrile illnesses (UFI) in Australia are unknown and it is possible that some of these are caused by the neglected arboviruses. The aims of this study were to determine the seroprevalence of antibodies against several neglected Australian arboviruses among residents of Queensland, north-east Australia, and to ascertain whether any are associated with UFI. One hundred age- and sex-stratified human plasma samples from blood donors in Queensland were tested to determine the prevalence of neutralising antibodies against ALFV, BFV, EHV, KOKV, KUNV, MVEV, RRV, SINV, and STRV. The seroconversion rates for RRV and BFV infections were 1.3 and 0.3% per annum, respectively. The prevalence of antibodies against ALFV was too low to enable estimates of annual infection rates to be determined, but the values obtained for other neglected viruses, EHV (0.1%), KOKV (0.05%), and STRV (0.05%), indicated that the numbers of clinical infections occurring with these agents are likely to be extremely small. This was borne out by the observation that only 5.7% of a panel of 492 acute phase sera from UFI patients contained IgM against any of these arboviruses, as detected by an indirect immunofluorescence assay. While none of these neglected arboviruses appear to be a cause of a significant number of UFIs in Australia at this time, each has the potential to emerge as a significant human pathogen if there are changes to their ecological niches.

The epidemiology and clinical features of rickettsial diseases in North Queensland, Australia: Implications for patient identification and management

Background

Rickettsial infections are a common cause of hospitalization in tropical settings, although early diagnosis is challenging in the rural locations where these infections are usually seen.

Methods

This retrospective, clinical audit of microbiologically-confirmed cases of scrub typhus or spotted fever group (SFG) rickettsial infection between 1997 and 2016 was performed a tertiary referral hospital in tropical Australia. Clinical, laboratory and radiological findings at presentation were correlated with the patients’ subsequent clinical course.

Results

There were 135 locally-acquired cases (95 scrub typhus, 37 SFG, 3 undifferentiated). There were nine hospitalizations during the first 5 years of the study period and 81 in the last 5 years (p for trend = 0.003). Eighteen (13%) of the 135 cases required ICU admission, all of whom were adults. A greater proportion of patients with SFG infection required ICU support (8/37 (22%) compared with 10/95 (11%) scrub typhus cases), although this difference did not reach statistical significance (p = 0.10). Three (8%) of the 37 patients with SFG infection had severe disease (1 died, 2 developed permanent disability) versus 0/95 scrub typhus patients (p = 0.02). Adults with a high admission qSOFA score (≥2) had an odds ratio (OR) of 19 (95% CI:4.8–74.5) for subsequent ICU admission (p<0.001); adults with a high NEWS2 score (≥7) had an OR of 14.3 (95% CI:4.5–45.32) for ICU admission (p<0.001). A patient’s respiratory rate at presentation had strong prognostic utility: if an adult had an admission respiratory rate <22 breaths/minute, the negative predictive value for subsequent ICU admission was 95% (95% CI 88–99).

Conclusions

In the well-resourced Australian health system outcomes are excellent, but the local burden of rickettsial disease appears to be increasing and the clinical phenotype of SFG infections may be more severe than previously believed. Simple, clinical assessment on admission has prognostic utility and may be used to guide management.

Rickettsial infections are a common cause of hospitalization in tropical settings, although early, definitive diagnosis is challenging in the rural and remote locations where they are usually seen. It is important to recognise rickettsial infections early in their disease course as they can lead to life-threatening multi-organ failure if specific anti-rickettsial antimicrobial therapy is not prescribed promptly. In tropical Australia, scrub typhus and spotted fever group (SFG) rickettsiae are the dominant rickettsial pathogens and this twenty-year retrospective series examines the clinical and laboratory findings which might facilitate their recognition. The study highlights the infections’ increasing local clinical burden and reports that over 20% of the SFG cases in the series required Intensive Care Unit (ICU) admission, suggesting that severe SFG disease may be more common than previously believed. Simple, clinical prediction scores—calculated at presentation—identified patients who would subsequently require ICU admission. Importantly, they were also able to identify patients at low risk of disease progression. These entirely clinical scores—which can be calculated rapidly at the bedside—have the potential to facilitate the management of patients with scrub typhus and SFG infection, particularly in resource-limited settings which have the greatest burden of disease.

Neglected Australian Arboviruses and Undifferentiated Febrile Illness: Addressing Public Health Challenges Arising From the 'Developing Northern Australia' Government Policy

The Australian Government is currently promoting the development of Northern Australia, with an associated increase in the local population. Consequent to this is the public health threat posed by heightened human exposure to many previously neglected arboviruses that are indigenous to the region. This initiative to support economic activity in the tropical north of the continent is leading to the accelerated expansion of an infection-naïve human population into hitherto un-encountered ecosystems inhabited by reservoir animals and vectors for these arboviruses. Combined with an apparent rise in the number and impact of dramatic climate events, such as tropical cyclones and floods caused by torrential monsoonal rainfall, this heightens the potential for viral transmission to humans. More than 75 arboviruses have been identified in Australia, some of which are associated with human disease but for which routine tests are not available to diagnose infection. Here, we describe briefly the neglected Australian arboviruses that are most likely to emerge as significant agents of human disease in the coming decades. We also advocate the establishment of a thorough surveillance and diagnostic protocol, including developing new pan-viral rapid tests for primary care use to assist in the early diagnosis and correct treatment of affected patients. We propose that the implementation of these activities will enhance our understanding of the geographical range, prevalence, identification and control of neglected Australian arboviruses. This would minimise and limit the possibility of large-scale outbreaks with these agents as population and economic growth expands further into Australia's tropical north.

Confronting the Emerging Threat to Public Health in Northern Australia of Neglected Indigenous Arboviruses

In excess of 75 arboviruses have been identified in Australia, some of which are now well established as causative agents of debilitating diseases. These include Ross River virus, Barmah Forest virus, and Murray Valley encephalitis virus, each of which may be detected by both antibody-based recognition and molecular typing. However, for most of the remaining arboviruses that may be associated with pathology in humans, routine tests are not available to diagnose infection. A number of these so-called 'neglected' or 'orphan' arboviruses that are indigenous to Australia might have been infecting humans at a regular rate for decades. Some of them may be associated with undifferentiated febrile illness-fever, the cause of which is not obvious-for which around half of all cases each year remain undiagnosed. This is of particular relevance to Northern Australia, given the Commonwealth Government's transformative vision for the midterm future of massive infrastructure investment in this region. An expansion of the industrial and business development of this previously underpopulated region is predicted. This is set to bring into intimate proximity infection-naïve human hosts, native reservoir animals, and vector mosquitoes, thereby creating a perfect storm for increased prevalence of infection with neglected Australian arboviruses. Moreover, the escalating rate and effects of climate change that are increasingly observed in the tropical north of the country are likely to lead to elevated numbers of arbovirus-transmitting mosquitoes. As a commensurate response, continuing assiduous attention to vector monitoring and control is required. In this overall context, improved epidemiological surveillance and diagnostic screening, including establishing novel, rapid pan-viral tests to facilitate early diagnosis and appropriate treatment of febrile primary care patients, should be considered a public health priority. Investment in a rigorous identification program would reduce the possibility of significant outbreaks of these indigenous arboviruses at a time when population growth accelerates in Northern Australia.

Estimating the burden of scrub typhus: A systematic review

BACKGROUND

Scrub typhus is a vector-borne zoonotic disease that can be life-threatening. There are no licensed vaccines, or vector control efforts in place. Despite increasing awareness in endemic regions, the public health burden and global distribution of scrub typhus remains poorly known.

METHODS

We systematically reviewed all literature from public health records, fever studies and reports available on the Ovid MEDLINE, Embase Classic + Embase and EconLit databases, to estimate the burden of scrub typhus since the year 2000.

FINDINGS

In prospective fever studies from Asia, scrub typhus is a leading cause of treatable non-malarial febrile illness. Sero-epidemiological data also suggest that Orientia tsutsugamushi infection is common across Asia, with seroprevalence ranging from 9.3%-27.9% (median 22.2% IQR 18.6-25.7). A substantial apparent rise in minimum disease incidence (median 4.6/100,000/10 years, highest in China with 11.2/100,000/10 years) was reported through passive national surveillance systems in South Korea, Japan, China, and Thailand. Case fatality risks from areas of reduced drug-susceptibility are reported at 12.2% and 13.6% for South India and northern Thailand, respectively. Mortality reports vary widely around a median mortality of 6.0% for untreated and 1.4% for treated scrub typhus. Limited evidence suggests high mortality in complicated scrub typhus with CNS involvement (13.6% mortality), multi-organ dysfunction (24.1%) and high pregnancy miscarriage rates with poor neonatal outcomes.

INTERPRETATION

Scrub typhus appears to be a truly neglected tropical disease mainly affecting rural populations, but increasingly also metropolitan areas. Rising minimum incidence rates have been reported over the past 8-10 years from countries with an established surveillance system. A wider distribution of scrub typhus beyond Asia is likely, based on reports from South America and Africa. Unfortunately, the quality and quantity of the available data on scrub typhus epidemiology is currently too limited for any economical, mathematical modeling or mapping approaches.

Neglected Australian arboviruses: quam gravis?

At least 75 arboviruses have been identified from Australia. Most have a zoonotic transmission cycle, maintained in the environment by cycling between arthropod vectors and susceptible mammalian or avian hosts. The primary arboviruses that cause human disease in Australia are Ross River, Barmah Forest, Murray Valley encephalitis, Kunjin and dengue. Several other arboviruses are associated with human disease but little is known about their clinical course and diagnostic testing is not routinely available. Given the significant prevalence of undifferentiated febrile illness in Australia, investigation of the potential threat to public health presented by these viruses is required.

Characteristics of acute febrile illness and determinants of illness recovery among adults presenting to Singapore primary care clinics

Background

Undifferentiated acute febrile illness (AFI) is a common presentation among adults in primary care settings in Singapore but large gaps exist in the understanding of the characteristics of these patients. We studied clinical and epidemiological characteristics of AFI patients and factors associated with delayed recovery from AFI.

Methods

We performed a secondary data analysis using data from the Early DENgue infection and outcome (EDEN) study on 2046 adult patients presenting at 5 Singapore polyclinics between December 2007 and February 2013 with a history of fever (≥38 °C) for less than 72 h. We used an accelerated failure time model to investigate factors associated with delayed recovery from AFI.

Results

The mean age of patients was 36.6 years, 65 % were male, 51 % were of Chinese ethnicity, and 75 % lived in public housing. Median illness duration was 5 days (interquartile range, 3–7). In multivariable analysis, the unemployed and white collar workers had longer illness duration compared with blue collar workers (time ratio (TR), 1.10; 95 % confidence interval (CI), 1.03–1.17 and TR, 1.08; 95 % CI, 1.02–1.15, respectively). Patients with more symptoms at initial consultation had slower recovery (TR, 1.03 per additional symptom; 95 % CI, 1.02–1.03). Other clinical factors were also associated with longer duration of illness, including use of analgesics (TR, 1.21; 95 % CI, 1.15–1.28); use of cough medicines (TR, 1.14; 95 % CI, 1.08–1.20); use of antibiotics (TR, 1.14; 95 % CI, 1.07–1.21); and hospitalization (TR, 1.59; 95 % CI, 1.39–1.82). Compared to patients with normal WBC count at first consultation, those with low WBC count had slower recovery (TR, 1.14; 95 % CI, 1.07–1.21), while the reverse was observed among patients with high WBC count (TR, 0.94; 95 % CI, 0.88–1.00).

Conclusions

Differences in illness duration among different types of employment may reflect differences in their underlying general health status. Early identification of factors delaying recovery could help triage management in a primary care setting. In-depth characterization of fever etiology in Singapore will improve surveillance and control activities.