A Case Series of Scrub Meningoencephalitis from a Tertiary Care Center in North India

Scrub typhus infection is reemerging leading cause of acute febrile illnesses in post-rainy or monsoon season in Southeast Asia. It is caused by Orientia tsutsugamushi and spread by the bite of chiggers, larval forms of trombiculid mites. The clinical picture can range from simple acute febrile illness to multiorgan dysfunction. Neurological manifestations also vary from aseptic meningitis, meningoencephalitis, cerebral infarction, acute disseminated encephalomyelitis, transverse myelitis, and psychiatric manifestations. Here, we present a case series of eight cases of scrub meningoencephalitis diagnosed based on clinical, laboratory, and radiological criteria.

Scrub Typhus in Children: A Prospective Observational Study in a Tertiary Care Hospital in Eastern India

Background Scrub typhus is a reemerging, acute, undifferentiating febrile illness and one of the most neglected tropical diseases, calling for an in-depth investigation into its clinical diversity, complications, and mortality, which drives us to carry out this research work. Methods Over a year, prospective observational research was carried out after gaining parental consent and institutional ethical clearance, 206 children of either gender aged between one month and 12 years who had been hospitalized with a fever for at least five days and subsequently tested positive for Orientia​​​​ tsutsugamushi were included in the study. Basic demographic information, clinical characteristics, laboratory findings, complications, related coinfections, and results were gathered and analyzed. A P-value of 0.05 was set as the statistical benchmark. Results The current study found that boys outnumbered girls. The ratio of boys to girls was 1.22:1, and the average age was 5.18 years. All had a fever (100%), and the other most frequently occurring clinical signs and symptoms were abdominal pain (16.99%), vomiting (22.33%), hepatosplenomegaly (49.51%), facial puffiness (39.32%), edema (27.18%), lymphadenopathy (19.90%), eschar (19.90%), macular-erythematous rash (17.96%), cough (21.84%), conjunctival congestion (25.24%), and headache (13.59%). Anemia (81.55%), leucocytosis (20.39%), leucopenia (6.8%), thrombocytopenia (49.51%), thrombocytosis (2.43%), and elevated serum levels of alanine aminotransferase (ALT, 57.28%) and aspartate aminotransferase (AST, 63.59%) were characteristic laboratory results. The coinfections were dengue, enteric fever, urinary tract infections, and malaria. Children who also had dengue were more likely to develop thrombocytopenia, which was statistically significant (P-value = 0.008). With doxycycline medication, early defervescence of fever occurred earlier than with azithromycin, and it was statistically significant (P-value = 0.000). The complications were hepatitis (63.59%), lower respiratory tract infections (LRTIs, 22.82%), scrub typhus meningoencephalitis (STME, 3.88%), acute kidney injury (AKI, 2.91%), myocarditis (1.46%), and acute disseminated encephalomyelitis (ADEM, 0.49%). Except for one who had ADEM, everyone was sent back home after receiving the best care possible. The average duration of hospital stay was 6.89 days. Conclusions Even in the absence of eschar, scrub typhus should be suspected in any febrile child who experiences clinical signs of meningoencephalitis syndrome, capillary leakage, skin rash, conjunctival congestion, LRTI, AKI, lymphadenopathy, hepatosplenomegaly, thrombocytopenia, and liver dysfunction in the post-monsoon season. Strong clinical suspicion and prompt anti-scrub drug administration go a long way in preventing or decreasing the morbidity and mortality of the same.

Brain transcriptomics reveal the activation of neuroinflammation pathways during acute Orientia tsutsugamushi infection in mice

Scrub typhus, an acute febrile illness caused by Orientia tsutsugamushi (Ot), is prevalent in endemic areas with one million new cases annually. Clinical observations suggest central nervous system (CNS) involvement in severe scrub typhus cases. Acute encephalitis syndrome (AES) associated with Ot infection is a major public health problem; however, the underlying mechanisms of neurological disorder remain poorly understood. By using a well-established murine model of severe scrub typhus and brain RNA-seq, we studied the brain transcriptome dynamics and identified the activated neuroinflammation pathways. Our data indicated a strong enrichment of several immune signaling and inflammation-related pathways at the onset of disease and prior to host death. The strongest upregulation of expression included genes involved in interferon (IFN) responses, defense response to bacteria, immunoglobulin-mediated immunity, IL-6/JAK-STAT signaling, and TNF signaling via NF-κB. We also found a significant increase in the expression of core genes related to blood-brain barrier (BBB) disruption and dysregulation in severe Ot infection. Brain tissue immunostaining and in vitro infection of microglia revealed microglial activation and proinflammatory cytokine production, suggesting a crucial role of microglia in neuroinflammation during scrub typhus. This study provides new insights into neuroinflammation in scrub typhus, highlighting the impact of excessive IFN responses, microglial activation, and BBB dysregulation on disease pathogenesis.

Scrub Typhus and Dengue Co-infection in an Adolescent Girl: A Diagnostic Challenge

Scrub typhus and dengue fever are common infectious diseases in tropical regions, and both have overlapping clinico-epidemiological and laboratory features, which often pose a diagnostic challenge. This case report discusses a 15-year-old girl from the Indian subcontinent who presented with acute undifferentiated febrile illness (AUFI) without typical features of any of the common tropical infections. She was diagnosed with co-infection of scrub typhus and dengue fever using laboratory tests with good diagnostic accuracy. The patient was managed on an ambulatory basis, treated with oral doxycycline, and showed symptomatic improvement within 48 hours. Co-infections in endemic areas present a significant diagnostic and therapeutic challenge. This case report highlights the importance of considering co-infections in the differential diagnosis of AUFI, especially during the post-monsoon period, and the use of highly sensitive and specific tests for the diagnosis of co-infections.

Costs & outcomes of hospitalized scrub typhus infection in a tertiary hospital in south India

Background & objectives

Scrub typhus is a rickettsial infection seen along the Asian-Pacific rim and imposes a considerable burden on affected people in low- and middle-income countries. The present study was aimed to determine the direct cost of hospitalization of scrub typhus and its trend over six years.

Methods

This was a retrospective, observational, hospital based study of individuals admitted to the hospital, diagnosed with scrub typhus over six years, from January 2013 to December 2018. The potential out of pocket expenditure was evaluated.

Results

A total of 198 patients were included in the study. The median cost of admission (adjusted to INR 2020) for the six years (2013 to 2018) was found to be ₹ 37,026 (US $ 490) [interquartile range (IQR) 22,996-64,992]. The median cost for patients admitted to the intensive care unit (ICU) was ₹ 128,046 (US $ 1695) (IQR 71,575-201,171), while the cost for patients admitted to the ward-alone was ₹ 33,232 (US $ 440) (IQR 19,609-45,373). The multivariable analysis showed that ARDS and SOFA score were the independent predictors of ICU admission.

Interpretation & conclusions

Hospitalisation for scrub typhus is associated with a substantial healthcare expense. The predictors of increased cost were the presence of acute respiratory distress syndrome (ARDS), shock, increasing sequential organ failure assessment (SOFA) score and duration of hospital stay.

Scrub Typhus Complicated With Fulminant Perimyocarditis

A 62-year-old woman with no systemic disease presented to the emergency department (ED) with acute febrile illness for three days. During her ED course, she developed respiratory distress and refractory cardiogenic shock with ST-elevation on electrocardiography. No occluded coronary vessel was found in angiography, and perimyocarditis was impressed. The serum indirect immunofluorescence assay was positive for scrub typhus. Hemopericardium and subsequently intracranial hemorrhage occurred on the 4th hospital day even under intensive care, and the patient expired. Perimyocarditis is a rare but fatal complication of scrub typhus. Through this case report, we aim to convey the genuine possibility that a fulminant perimyocarditis may occur in a previously healthy adult as a potential complication of scrub typhus. By recognizing the risk factors of scrub typhus-related myocarditis, an ED physician can maintain a high index of suspicion for the cardiac complication and intervene in a timely manner.

Determination of a cut-off value for the serological diagnosis of scrub typhus by detecting anti-Orientia tsutsugamushi immunoglobulin M

Background & objectives

The diagnosis of scrub typhus (ST) is usually done using enzyme-linked immunosorbent assay (ELISA) due to its ease of performance and reading objectivity. The cut-off value for ELISA needs to be calculated for each geographical location as it depends on zonal endemicity of the disease. This study was, therefore, undertaken to calculate the pan-India cut-off for anti-Orientia tsutsugamushi (OT) immunoglobulin M (IgM) by ELISA.

Methods

Samples from cases (cases of ST) and controls (voluntary, consenting, healthy adults) were collected by a network of 29 laboratories across India and tested for anti-OT IgM by immunofluorescence assay (IFA), the considered gold standard test. These samples were retested by ELISA for anti-OT IgM and their optical densities (ODs) were used for cut-off estimation by receiver operating characteristic (ROC) curve.

Results

Anti-OT IgM ELISA ODs from 273 controls and 136 cases were used for the cut-off estimation. The ODs of the anti-OT IgM ELISA on healthy individuals and those of confirmed ST cases ranged from 0.1 to 0.75 and 0.5 to 4.718, respectively. ROC curve-based cut-off for ELISA was calculated as 0.554 at a sensitivity of 95.2 per cent and specificity of 95.1 per cent. A value of >1 was noted to have a specificity of 100 per cent in diagnosing ST.

Interpretation & conclusions

The cut-off calculated for India was similar to the previous cut-off that was used until now.

Prediction of risk factors for scrub typhus from 2006 to 2019 based on random forest model in Guangzhou, China

OBJECTIVES

Scrub typhus is an increasingly serious public health problem, which is becoming the most common vector-borne disease in Guangzhou. This study aimed to analyse the correlation between scrub typhus incidence and potential factors and rank the importance of influential factors.

METHODS

We collected monthly scrub typhus cases, meteorological variables, rodent density (RD), Normalised Difference Vegetation Index (NDVI), and land use type in Guangzhou from 2006 to 2019. Correlation analysis and a random forest model were used to identify the risk factors for scrub typhus and predict the importance rank of influencing factors related to scrub typhus incidence.

RESULTS

The epidemiological results of the scrub typhus cases in Guangzhou between 2006 and 2019 showed that the incidence rate was on the rise. The results of correlation analysis revealed that a positive relationship between scrub typhus incidence and meteorological factors of mean temperature (T_mean ), accumulative rainfall (RF), relative humidity (RH), sunshine hours (SH), and NDVI, RD, population density, and green land coverage area (all p < 0.001). Additionally, we tested the relationship between the incidence of scrub typhus and the lagging meteorological factors through cross-correlation function, and found that incidence was positively correlated with 1-month lag T_mean , 2-month lag RF, 2-month lag RH, and 6-month lag SH (all p < 0.001). Based on the random forest model, we found that the T_mean was the most important predictor among the influential factors, followed by NDVI.

CONCLUSIONS

Meteorological factors, NDVI, RD, and land use type jointly affect the incidence of scrub typhus in Guangzhou. Our results provide a better understanding of the influential factors correlated with scrub typus, which can improve our capacity for biological monitoring and help public health authorities to formulate disease control strategies.

"Back to the Jungle": Investigating Rats, Grass, Scrub Typhus, and Plantations in Malaya, 1924 - 1974

In this article, I examine epidemiological research into scrub typhus in British Malaya between 1924 and 1974. Interwar research, I show, explained the incidence of the disease through conjunctions of rats, mites, plantations, lalang grass, and "jungle." In the process, interwar researchers bridged a novel scientific vocabulary centering on disease "reservoirs" with older suspicions of plantations enabling "pests," as well as with a later, explicitly ecological understanding of infectious disease. In exploring this history I thereby help to re-historicize the emergence of ecological notions of disease reservoirs, whilst also pushing at the limit-points of influential notions of "tropicality."

Case Report: Optic neuritis as the initial presentation of Orientia tsutsugamushi infection detected by metagenomic next-generation sequencing

Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi infection, and typically manifested as fever, eschar, lymphadenopathy, rash, and other flu-like signs. Ocular involvement was not uncommon, and mostly occurred at post-fever or recovery stage in scrub typhus cases. We hereby report a case of scrub typhus presenting as unilateral optic neuritis (ON). A 56-year-old man going wild fishing nearly every day complained of a blurred vision and an inferior visual field defect in the right eye two or three days after an insect-bite like shin induration in his left leg. He was diagnosed as ON, and treated with dexamethasone in the local hospital. Unfortunately, his right eye vision progressively deteriorated during steroid therapy. Three days after steroid therapy ceased, he suffered from a high fever and painful subcutaneous masses in the left groin. Peripheral blood test by metagenomic next-generation sequencing (mNGS) was positive for Orientia tsutsugamushi, but negative for other pathogens. The diagnosis was then revised to scrub typhus and ON. His systemic symptoms rapidly disappeared after oral doxycycline and omadacycline therapy. However, his right eye vision continuously deteriorated to hand motion. Further serum tests for aquaporin 4-IgG antibody and myelin oligodendrocyte glycoprotein-IgG antibody were both negative, but for anticardiolipin IgM and beta-2-glycoprotein-I IgM were both positive. The patient's right eye vision gradually improved after doxycycline combined with steroid pulse therapy. Our case indicates that ON in scrub typhus cases may present as a parainfectious inflammation, and that mNGS is a useful and valuable method for early diagnosis of scrub typhus.

Environmental, Occupational, and Demographic Risk Factors for Clinical Scrub Typhus, Bhutan

Underdiagnosis and underreporting of scrub typhus has increasingly affected public health in Bhutan since its initial detection in 2008. Identifying scrub typhus risk factors would support early diagnosis and treatment for this nonspecific febrile disease, reducing the incidence of potentially fatal complications. We conducted a hospital-based, case‒control study during October‒December 2015 in 11 scrub typhus‒prone districts. We identified harvesting cardamom as the major risk factor (odds ratio 1,519; p<0.001); other factors were traditional housing, largely caused by an outside toilet location, as well as owning a goat and frequently sitting on grass. Harvesting vegetables, herding cattle in the forest, and female sex were protective. Age had a nonlinear effect; children and the elderly were more likely to seek treatment for clinical scrub typhus. This study has informed public health policies and awareness programs for healthcare workers through development of National Guidelines for Prevention, Treatment and Control of Scrub Typhus in Bhutan.

A case of acute encephalitis syndrome and cranial nerve palsy secondary to scrub typhus: A rare presentation from Western Nepal

Key Clinical Message

This case report highlights the importance of considering scrub typhus as a differential diagnosis for acute encephalitis with cranial nerve palsy in the region of the tsutsugamushi triangle.

Abstract

Scrub typhus is a zoonotic rickettsiosis caused by the bacterium Orientia tsutsugamushi. This disease is endemic to a region called the tsutsugamushi triangle that extends from Southeast Asia to the Pacific Ocean. We report a 17-year-old girl from western Nepal who presented with fever, headache, vomiting, and altered sensorium, as well as bilateral lateral rectus palsy, dysphagia, regurgitation of food, dysarthria, and left-sided upper motor neuron type facial palsy. Following laboratory and imaging tests, the patient was diagnosed with scrub typhus and was treated successfully with high-dose dexamethasone and doxycycline. This case highlights the importance of considering scrub typhus in the differential diagnosis of encephalitis with cranial nerve palsy, especially in the region of the tsutsugamushi triangle. It also emphasizes the need for timely diagnosis and treatment of scrub typhus to prevent the development of various complications and ensure earlier recovery of patients.

Etiological Profile and Clinico Epidemiological Patterns of Acute Encephalitis Syndrome in Tamil Nadu, India

Introduction

Establishing the etiological cause of acute encephalitis syndrome (AES) is challenging due to the distinct distribution of various etiological agents. This study aims to determine the etiological profiles of both viruses and bacteria and their associated clinico-epidemiological features among the AES suspected cases in Tamil Nadu, India.

Methods

Samples of 5136 suspected AES cases from January 2016 to December 2020 (5 years) were subjected to the detection of etiological agents for AES through serological and molecular diagnosis methods. Further, the clinical profile, age- and gender-wise susceptibility of cases, co-infection with other AES etiological agents, and seasonality pattern with respect to various etiological agents were examined.

Results

AES positivity was established in 1480 cases (28.82%) among the 5136 suspected cases and the positivity for male and female groups were 57.77% and 42.23%, respectively. The pediatric group was found to be more susceptible than others. Among the etiological agents tested, the Japanese encephalitis virus (JEV) was the predominant followed by Cytomegalovirus, Herpes Simplex virus, Epstein-Barr virus, Varicella Zoster virus, and others. Co-infection with other AES etiological agents was observed in 3.5% of AES-positive cases. Seasonality was observed only for vector-borne diseases such as JEV, dengue virus, and West Nile virus infections in this study.

Conclusion

AES was found to be a significant burden for Tamil Nadu with a diverse etiological spectrum including both sporadic and outbreak forms. Overlapping clinical manifestations of AES agents necessitate the development of region-specific diagnostic algorithm with distinct etiological profiles for early detection and effective case management.

Association of Scrub Typhus in Children with Acute Encephalitis Syndrome and Meningoencephalitis, Southern India

Scrub typhus is an established cause of acute encephalitis syndrome (AES) in northern states of India. We systematically investigated 376 children with AES in southern India, using a stepwise diagnostic strategy for the causative agent of scrub typhus, Orientia tsutsugamushi, including IgM and PCR testing of blood and cerebrospinal fluid (CSF) to grade its association with AES. We diagnosed scrub typhus in 87 (23%) children; of those, association with AES was confirmed in 16 (18%) cases, probable in 55 (63%), and possible in 16 (18%). IgM detection in CSF had a sensitivity of 93% and specificity of 82% compared with PCR. Our findings suggest scrub typhus as an emerging common treatable cause of AES in children in southern India and highlight the importance of routine testing for scrub typhus in diagnostic algorithms. Our results also suggest the potential promise of IgM screening of CSF for diagnosis of AES resulting from scrub typhus.

Imported Rickettsial Infections to the United Kingdom, 2015-2020

OBJECTIVE

The burden of imported rickettsial infection in the UK is not previously described. This retrospective review identifies rickettsial cases diagnosed at the national reference laboratory between 2015-2022.

METHODS

Samples testing positive for spotted fever group, typhus group and scrub typhus IgG/IgM on acute and convalescent blood samples, and/or PCR on tissue/blood were categorised as suspected, confirmed or past infection.

RESULTS

220 patients had rickettsioses, the commonest import was acute spotted fever group infection (61%, 125/205), 54% (62/114) from South Africa. Acute typhus group cases, 60% (40/67) from Southeast Asia. One patient with Rickettsia typhi bacteremia died. Scrub typhus group infections (5%, 10/205) were exclusively from Asia and the Western Pacific regions. Overall, 43% of confirmed cases (39/91) had not received doxycycline prior to results.

CONCLUSIONS

Rickettsial infections are important and under-recognised causes of imported fever in the UK. Thorough history, examination and timely treatment with doxycycline should be considered if there is suspicion of Rickettsia infection before testing.

Co-infection of dengue, scrub typhus, and typhoid during dengue outbreak in Nepal, 2022: A case report

In midst of the recent dengue outbreak in Nepal, in 2022, the risk of co-infection increases and may lead to fatal outcomes if the diagnosis of multiple infections is delayed. Thus, all available diagnostic approaches must be taken to decrease the burden of illness and lessen mortality.

An Alternative Splicing Variant of the Mixed-Lineage Leukemia 5 Protein Is a Cellular Adhesion Receptor for ScaA of Orientia tsutsugamushi

Scrub typhus is a mite-borne disease caused by the obligately intracellular bacterium Orientia tsutsugamushi. We previously demonstrated that ScaA, an autotransporter membrane protein of O. tsutsugamushi, is commonly shared in various genotypes and involved in adherence to host cells. Here, we identified a mixed-lineage leukemia 5 (MLL5) mammalian trithorax group protein as a host receptor that interacts with ScaA. MLL5, identified by yeast two-hybrid screening, is an alternative splicing variant of MLL5 (vMLL5) which contains 13 exons with additional intron sequences encoding a tentative transmembrane domain. Indeed, vMLL5 is expressed on the plasma membrane as well as in intracellular compartments in eukaryotic cells and colocalized with adherent O. tsutsugamushi. In addition, ScaA-expressing Escherichia coli showed significantly increased adherence to vMLL5-overexpressing cells compared with vector control cells. We mapped the C-terminal region of the passenger domain of ScaA as a ligand for vMLL5 and determined that the Su(var)3-9, Enhancer of zeste, Trithorax (SET) domain of MLL5 is an essential and sufficient motif for ScaA binding. We observed significant and specific inhibition of bacterial adhesion to host cells in competitive inhibition assays using the C-terminal fragment of ScaA or the SET domain of vMLL5. Moreover, immunization with the C-terminal fragment of ScaA provided neutralizing activity and protective immunity against lethal challenge with O. tsutsugamushi as efficiently as vaccination with the whole passenger domain of ScaA. These results indicate that vMLL5 is a novel cellular receptor for ScaA-mediated adhesion of O. tsutsugamushi and facilitates bacterial adhesion to host cells, thereby enhancing bacterial infection. IMPORTANCE O. tsutsugamushi is a mite-borne pathogen that causes scrub typhus. As an obligately intracellular pathogen, its adhesion to and invasion of host cells are critical steps for bacterial growth. However, the molecular basis of the bacterial ligand and host receptor interaction is poorly defined. Here, we identified a splicing variant of MLL5 (vMLL5) as a cellular adhesion receptor of ScaA, an outer membrane autotransporter protein of O. tsutsugamushi. We mapped the interacting domains in the bacterial ligand and host receptor and confirmed their functional interaction. In addition, immunization with the C-terminal region of ScaA, which involves an interaction with the SET domain of vMLL5, not only induces enhanced neutralizing antibodies but also provides protective immunity against lethal challenge with O. tsutsugamushi.

Clinical features and risk factors for death in acute undifferentiated fever: A prospective observational study in rural community hospitals in six states of India

BACKGROUND

Acute undifferentiated fever (AUF) ranges from self-limiting illness to life-threatening infections, such as sepsis, malaria, dengue, leptospirosis and rickettsioses. Similar clinical presentation challenges the clinical management. This study describes risk factors for death in patients hospitalized with AUF in India.

METHODS

Patients aged ≥5 y admitted with fever for 2-14 d without localizing signs were included in a prospective observational study at seven hospitals in India during 2011-2012. Predictors identified by univariate analysis were analyzed by multivariate logistic regression for survival analysis.

RESULTS

Mortality was 2.4% (37/1521) and 46.9% (15/32) died within 2 d. History of heart disease (p=0.013), steroid use (p=0.011), altered consciousness (p<0.0001), bleeding (p<0.0001), oliguria (p=0.020) and breathlessness (p=0.015) were predictors of death, as were reduced Glasgow coma score (p=0.005), low urinary output (p=0.004), abnormal breathing (p=0.006), abdominal tenderness (p=0.023), leucocytosis (p<0.0001) and thrombocytopenia (p=0.001) at admission. Etiology was identified in 48.6% (18/37) of fatal cases.

CONCLUSIONS

Bleeding, cerebral dysfunction, respiratory failure and oliguria at admission, suggestive of severe organ failure secondary to systemic infection, were predictors of death. Almost half of the patients who died, died shortly after admission, which, together with organ failure, suggests that delay in hospitalization and, consequently, delayed treatment, contribute to death from AUF.

Molecular Detection of Candidatus Orientia chuto in Wildlife, Saudi Arabia

Scrub typhus is a zoonosis caused by 3 species of Orientia bacteria, including Candidatus Orientia chuto. This species is known only from a human case in Dubai and infections in wildlife in Kenya. We report molecular detection of Candidatus O. chuto in 2 wild rodent species from Saudi Arabia.

Acute Onset Postpartum Pleural Effusion: A Near-Miss Maternal Case Due to Scrub Typhus Infection

A 32-year-old puerperal patient developed acute onset breathlessness and fever on the third postoperative day. On evaluation, the patient was diagnosed to have scrub typhus pneumonia without any characteristic eschar. The condition was associated with pleural effusion, and it was drained. Azithromycin was used as the drug of choice due to the peripartum status of this patient. The patient improved due to early detection and multidisciplinary timely care. The safe outcome of this near-miss case suggests that fever profile workup, especially in scrub typhus endemic areas, should include scrub typhus testing even if classical signs are absent in the peripartum period.

Serologic Evidence of Orientia Infection among Rural Population, Cauca Department, Colombia

We assessed serum samples collected in Cauca Department, Colombia, from 486 persons for Orientia seroreactivity. Overall, 13.8% showed reactive IgG by indirect immunofluorescence antibody assay and ELISA. Of those samples, 30% (20/67) were confirmed to be positive by Western blot, showing >1 reactive band to Orientia 56-kD or 47-kD antigens.

Concurrent Infection with SARS-CoV-2 and Orientia tsutsugamushi during the COVID-19 Pandemic in the Maldives

The COVID-19 pandemic was the worst public-health crisis in recent history. The impact of the pandemic in tropical regions was further complicated by other endemic tropical diseases, which can cause concurrent infections along with COVID-19. Here, we describe the clinical course of a patient with concurrent COVID-19 and scrub typhus infection. The patient's de-identified clinical data were retrieved retrospectively. The patient had progressive breathlessness at the time of presentation and was hospitalized for COVID-19. Respiratory examination revealed dyspnea, tachypnea, and coarse crepitations bilaterally over the entire lung field. Oxygenation was impaired, and a PaO₂/FiO₂ ratio of 229 suggested acute respiratory distress syndrome. Laboratory tests indicated leukocytosis, thrombocytopenia, ferritinemia, hypoalbuminemia, and transaminitis. Upon revaluation for persistent fever, physical examination revealed an eschar in the right antecubital fossa. Serology further confirmed scrub typhus, with IgM and IgG antibody positivity. A remarkable clinical recovery was achieved with doxycycline. The COVID-19 pandemic might have masked endemic tropical diseases. Clinicians working in endemic regions must always consider common tropical diseases that may present as a co-infection, as in our case. Travel and exposure history are critical guides for narrowing down a differential diagnosis. Early diagnosis and treatment can prevent complications.

Seroprevalence of scrub typhus and other rickettsial diseases among the household rodents of Mizoram, North-East India

In the last decade, scrub typhus, a zoonotic disease has emerged as a major health concern in Mizoram, a North-East Indian state that shares international borders with Myanmar and Bangladesh. Mizoram is a biodiversity hotspot and >85% of the state is under forest cover, which provides an ideal ecological niche for the rodents and mites to transmit scrub typhus and other rickettsial infections. Using the Weil-Felix test, a serosurvey of household rodents from 41 villages spread across all the 11 districts in Mizoram was undertaken to gather important insights on their role in disease transmission. Furthermore, the chigger and flea indexes were calculated from the captured rodents. The 163 rodents captured belonged to five species; the highest numbers were from Rattus tanezumi (87), followed by Rattus rattus (41), Mus musculus (17), Suncus murinus (16), and Bandicota bengalensis (2). The rickettsial seropositivity of the captured rodents was 66.26% (108 out of 163 were positive). Among the 163 rodents, sera of 75 (46.01%), 61 (37.42%), and 73 (44.78%) were reactive to OXK, OX19, and OX2 antigens, respectively. The chigger and flea index were 17.92 and 0.16, respectively. Overall, the study has given important insights into the risk of multiple rickettsial infections that household rodents could transmit in Mizoram. These findings indicate the need for the urgent implementation of effective rodent control strategies in Mizoram.

Scrub typhus seroprevalence from an eastern state of India: findings from the state-wide serosurvey

BACKGROUND

Scrub typhus is a mite-borne infectious disease caused primarily by the obligate intracellular bacteria Orientia tsutsugamushi, which is transmitted by chigger mites. The objective of this study was to determine the prevalence of scrub typhus among adults in Odisha, an eastern state of India.

METHODS

A descriptive cross-sectional study was conducted to analyse 1840 serum samples from five districts (Khordha, Cuttack, Ganjam, Malkangiri and Sundargarh) of Odisha collected during 2020-2021. Both immunoglobulin G (IgG) and IgM antibodies against scrub typhus were tested using commercial enzyme-linked immunosorbent assay kits. Point estimates of the 95% confidence interval and adjusted odds ratio were calculated.

RESULTS

Of 1840 participants, the prevalence of IgG positivity was 1034 (56.19%) and that of IgM was 523 (28.42%). The majority of participants were in the 18-45 y age group (53.7%). Cuttack had the highest IgG positivity (64.54%) and Malkangiri had the lowest (29.32%). The highest and lowest positivity for IgM were found in Malkangiri (40.84%) and Cuttack (25.30%), respectively.

CONCLUSIONS

With an increasing number of infections detected in the state, scrub typhus is emerging as a public health threat. Increasing awareness among the general public and healthcare professionals through health education campaigns regarding scrub typhus is essential. Early detection of the disease through the establishment of a laboratory surveillance system is required to control the transmission of scrub typhus.

Monitoring Weil-Felix test in epidemic retinitis

Purpose

The objective was to study the positivity of the Weil-Felix test (WFT) in epidemic retinitis (ER) during the course of the disease.

Methods

This is a retrospective, observational case series of patients diagnosed with ER and presented to a tertiary eye care hospital in south India. Patients with positive WFT at the presentation, and who underwent a follow-up WFT during or after the resolution of ER were studied from September 2019 to March 2022. Patient's demographics, timings of clinical presentation and resolution, and investigation details with a special focus on WFT positivity and its duration were noted.

Results

Sixteen patients were studied. Patients presented after 5 weeks of the fever (range: 2-12 weeks, median: 4). After 1-2 months, WFT was still positive in eight patients (50%). Only in one patient titers increased after 1 month, while in others, the titers decreased (n = 11) or remained the same (n = 4). Repeated tests in those patients (n = 6) after 3-4 months turned negative. Resolution of ER was seen at 1.35 months (range: 1-3 months) after the presentation. The mean duration for WFT to turn negative was 2 months from the presentation (range: 1-4 months) or 3.2 months of the fever (range: 1.5-6 months).

Conclusion

In contrast to the reported physician's observation of increasing titers of WFT after rickettsial fever, ophthalmologists may observe decreasing WFT titers in ER. The clinical resolution of ER may precede the normalization of WFT. Follow-up WFT titers should be studied in larger series in confirmed cases of rickettsial-ER to validate the affordable and readily available WFT in India.