Trombiculid Mites Research Articles

Emerging trends of scrub typhus disease in southern Rajasthan, India: A neglected public health problem.

Scrub typhus is the oldest known vector-borne zoonotic infectious disease in the world which is life-threatening for all age groups as it presents acute febrile illness along with multi-organ involvements and spread with the biting of infectious 'Trombiculid mite' (chigger mite). The pathogen of this disease is an obligatory coccobacillus gram-negative rickettsial bacteria Orientia tsutsugamushi. Scrub typhus disease was previously confined geographically only to the Asia Pacific region (tsutsugamushi triangle), but in recent years it has crossed its limit and has spread in other countries beyond the tsutsugamushi triangle and has become more hazardous for the community. The objective of this study is to explore the scrub typhus disease outbreak trends with existing information in southern Rajasthan state, India. This study concluded that scrub typhus disease is being re-emerged again and again in various Indian geographical regions with new species of vectors. The disease has been raised in tremendous amounts in Rajasthan within the last five years especially in the hilly zone and has led to major public health problems with other zoonotic diseases.

Molecular epidemiology of Orientia tsutsugamushi from outbreak regions, Madhya Pradesh, central India.

Scrub typhus is a seriously neglected life threatening disease in Asia and the islands of the Pacific and Indian oceans. The causative agent is Orientia tsutsugamushi, an obligate intra-cytosolic bacterium transmitted to vertebrate animals such as human or rodent by larval trombiculid mites (chiggers). Here, we conducted an outbreak investigation in Madhya Pradesh state in central India after sudden upsurge in scrub typhus cases and mortality in humans. Sixty-five live traps were placed for capturing the rodents. The captured rodent species were identified and the samples were subjected to nested PCR targeting 56kDa TSA gene. Analysis revealed for the first-time predominant circulation of Karp genotype in this region. The vector species involved in transmission is Leptotrobidium deliense. In conclusion, we reported the circulation of Karp strain in outbreak regions of Madhya Pradesh and suggest that public health monitoring and surveillance needs to be improved. Studies on antigenic diversity, association of strains with clinical spectrum and pathogenicity in the local setup will be essential for development of region-specific diagnostics and vaccines.

Parasitism, seasonality, and diversity of trombiculid mites (Trombidiformes: Parasitengona, Trombiculidae) infesting bats (Chiroptera) in Poland

The study aims to ascertain the diversity of trombiculid species associated with Chiroptera in Poland, and for the first time in the case of research on Central European Trombiculidae, we use both DNA and morphology in an integrative taxonomic approach to determine species identities of trombiculids. The research was carried out from 2015 to 2019. In total, 2725 larvae were collected from 300 specimens of bats belonging to 11 species. Deutonymphs were obtained through laboratory rearing of larvae; few larvae and deutonymphs were collected also from bats' daily roosts. The presence of trombiculid larvae on hosts was observed between July and April of the following year, with the highest numbers recorded in autumn, during bat swarming. Male bats were infested more often than females (16.4 vs. 6.6%). The highest infestation rate was recorded for Barbastella barbastellus, Myotis nattereri and Plecotus auritus, and the highest prevalence of chiggers (> 30%) for Myotis bechsteinii and P. auritus. The larvae found on bats occupied the areas with free access to the host’s skin: auricles, tragus, and snout. Morphological identification of specimens to the species level was hindered by the mosaic distribution of diagnostic traits. Morphological analyses indicated the presence of Leptotrombidium russicum and Leptotrombidium spp. in the examined material, whereas molecular analyses additionally suggested three other potential species assigned to the same genus based on the assessed scope of intrageneric variation (ASAP method). We argue that the identification of the parasitic larvae (chiggers) using morphological characters does not address the question of actual species boundaries, which, in turn, affects the inferences about host specificity and host range.

Populations of the invasive Mediterranean red bug, Scantius aegyptius (Linnaeus, 1758) (Hemiptera: Heteroptera: Pyrrhocoridae), now widely established around Phoenix, Arizona, U.S.A.

The invasive pyrrhocorid bug, Scantius aegytpius (Linnaeus, 1758), was first reported in the United States from California in 2009, and the authors now report its spread to neighboring Arizona for the first time and analyze its distribution within the state. Vouchered physical specimens and photographic records confirm the presence of the species in Maricopa and Yavapai Counties, and photographic records additionally suggest the presence of the species in Coconino County. Notes regarding the biology and seasonality of the species are included, along with discussion on the usefulness of the community science resources iNaturalist and BugGuide for tracking the spread of some newly emergent invasive species.

Detection of Orientia tsutsugamushi in Novel Trombiculid Mite Species in Northern Tamil Nadu, India: Use of Targeting the Multicopy traD Gene.

Detection of Orientia tsutsugamushi DNA in a trombiculid mite chigger species suggests that it might be a potential vector of scrub typhus in an endemic area. Over a period of 20 mo, 85 rats were trapped, 57 had chiggers that were identified by standard morphometric techniques. The chigger pools were assessed by performing PCR assays targeting fragments of the single-copy genes 56 kDa type-specific antigen gene (TSA56) by nested PCR and the 47 kDa (htrA) quantitative real-time PCR (qPCR). The novel traD SYBR green assay that detects a multicopy gene was also performed. In total, 27 chigger pools were positive by traD qPCR, of which only 7 were positive by 47 kDa qPCR and in 3 of these, 56 kDa gene was amplified by nested PCR. Orientia tsutsugamushi-specific DNA was detected in Ascoschoengastia spp., Schoengastiella ligula, Leptotrombidium rajasthanense, Leptotrombidium deliense, and Leptotrombidium jayawickremei chigger pools. Therefore, they could be potential vectors of scrub typhus in Southern India. The three 56 kDa sequences belonged to TA716 genotype and Kato genogroup. Further studies are needed to confirm these chigger species as scrub typhus vectors in Northern Tamil Nadu.

Distribution pattern of chigger mites in south Tamil Nadu, India

Chiggers, the larval Trombiculid mites are the vectors for scrub typhus. Rodents and shrews are the preferred host. Study made at different habitats of chiggers collected in rodents and shrews, revealed more number to Rattus rattus 95(63%) and Suncus murinus 33(22%). Rattus rattus 31(54%) and Suncus murinus 17(30%) alone contributed more in chigger positivity. Chigger mites belonged to eight species under five genera. Leptotrombidium deliense (66%), Schoengatiella ligula (15%), and other chiggers (9%) were collected from 57 positive rodents. Seasonally, there was a significant difference in rodent positivity, and there was no significant difference in the number of chiggers collected. The study indicated the prevalence of chiggers in the various hosts and their variation in rodent/shrew hosts. R. rattus 31(54%) and S. murinus 17(30%) contributed more in chiggers infestation and seasonally wet-cool months favored more chiggers and host positivity from different habitats.

A study on serodiagnosis of scrub typhus in a Teaching Hospital of South India

Background: crub typhus is caused by Orientia tsutsugamushi (rickettsial disease) commonly transmitted by the bite of larval chiggers of trombiculid mites. It has been one of the important causes of febrile illness, especially in south India. The clinical diagnosis is difficult owing to the non-specific presentation. We in the current study tried to evaluate the serodiagnosis of scrub typhus with the Weil Felix test and IgM ELISA. Methods: This study was conducted in the Department of Microbiology, Prathima Institute of Medical Sciences, Naganoor, Karimnagar. All the sera samples were subjected to the Weil Felix test using Proteus OX2, OX19, OX-K strain agglutination test, and subsequently, Scrub typhus IgM ELISA test. Results: All the samples were subjected to the Weil Felix test n=4(6.06%) were positive for scrub typhus (OXK antigen) n=11(16.67%) were positive for the spotted group of fever (OX2 antigen) and n=10 (15.15%) were positive of typhus group (OX19 antigen). N=5 sera samples were positive for more than one type of antigens. All the n=66 serum samples were subjected to IgM ELISA for scrub typhus. Out of n=66, only two serum samples (3.03%) were positive by IgM ELISA. Conclusion: Scrub typhus is emerging as an important public health issue. It is one of the important causes of acute febrile illness. Although it is difficult to distinguish scrub typhus based on the clinical symptoms alone a simple test such as Weil Felix was found to be promising in the diagnosis of scrub typhus. ELISA IgM test may be performed additionally in laboratories with adequate facilities. Hence for clinicians, any case with a fever of unknown origin should arouse suspicion of scrub typhus

Commensal Rodent Habitat Expansion Enhances Arthropod Disease Vectors on a Tropical Volcanic Island.

On volcanic islands, the release of animals from predators and competitors can lead to increased body size and population density as well as the expanded habitat use of introduced animals relative to their mainland counterparts. Such alterations might facilitate the spread of diseases on islands when these exotic animals also carry pathogenic agents; however, this has rarely been investigated. The commensal Asian house rat (Rattus tanezumi) is confined to human residential surroundings in mainland Taiwan but can be observed in the forests of nearby Orchid Island, which is a tropical volcanic island. Orchid Island is also a hot spot for scrub typhus, a lethal febrile disease transmitted by larval trombiculid mites (chiggers) that are infected primarily with the rickettsia Orientia tsutsugamushi (OT). We predicted an increase in chigger abundance when rodents (the primary host of chiggers) invade forests from human settlements since soils are largely absent in the latter habitat but necessary for the survival of nymphal and adult mites. A trimonthly rodent survey at 10 sites in three habitats (human residential, grassland, and forest) found only R. tanezumi and showed more R. tanezumi and chiggers in forests than in human residential sites. There was a positive association between rodent and chigger abundance, as well as between rodent body weight and chigger load. Lastly, >95% of chiggers were Leptotrombidium deliense and their OT infection rates were similar among all habitats. Our study demonstrated potentially elevated risks of scrub typhus when this commensal rat species is allowed to invade natural habitats on islands. Additionally, while the success of invasive species can be ascribed to their parasites being left behind, island invaders might instead obtain more parasites if the parasite requires only a single host (e.g., trombiculid mite), is a host generalist (e.g., L. deliense), and is transferred from unsuitable to suitable habitats (i.e., human settlements on the mainland to forests on an island).

English

BACKGROUND Scrub typhus is a mite borne zoonotic bacterial disease caused by Orientia tsutsugamushi. It is transmitted by bite of chiggers of trombiculid mite. Clinical features generally include fever, headache, and myalgia, with or without eschar/rash. People with severe illness may develop organ failure and bleeding which can be fatal if left untreated. This study was done to detect outbreak of cases of scrub typhus in Eastern India. These mites generally live in paddy fields of forested area and people visiting those areas are generally affected. Now a days these mites migrate to urban area resulting in increased incidence of scrub typhus infection in urban area. This study was conducted in collaboration with another institute. The purpose of this study was to find out the incidence of scrub typhus in our area and the relationship between occurrence of scrub typhus and seasonal, age and sex variation. METHODS This study was carried out in our tertiary care hospital with 441 samples for a period of one year (01.01.2019 to 31.12.19). All the blood samples collected from febrile patients were subjected to Weil Felix test. If the titre is > 1 : 160; this was further confirmed by specific IgM testing. Both Weil-Felix tests and IgM scrub typhus positive tests were noted. RESULTS Out of 441 samples, 98 (22.2 %, n = 441) samples were positive for both WeilFelix and scrub typhus IgM by enzyme linked immunosorbent assay (ELISA) testing. Most of the cases were seen in males. Seasonal distribution showed higher cases in the months of September and October. CONCLUSIONS In our study, the highest numbers of scrub typhus cases were found in rural areas, during the harvesting period of July–September specially in monsoon or post monsoon period when there is abundance of mite larva. This infection is also reported high in cases among children in the age group of 1 - 14 years. Patients who tested positive for scrub typhus improved radically with doxycycline. KEYWORDS Orientia Tsutsugamushi, Scrub Typhus, IgM ELISA

SECONDARY HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS IN A CHILD WITH CONCOMITANT EBSTEIN BARR VIRUS AND SCRUB TYPHUS INFECTION – A RARE ENTITY

Scrub typhus is a life threatening zoonosis caused by Orientia tsutsugamushi organisms that are transmitted by the larvae of trombiculid mites. It is endemic to a geographically distinct region, the so called Tsutsugamushi triangle, which includes Japan, China and South Korea. The disease is more prevalent in southern and northern India.It is characterised by focal or disseminated vasculitis and perivasculitis involving the lungs, liver, spleen and central nervous system. We report our experience with pediatric scrub typhus at a hospital in eastern India with EBV positive and secondary HLH. An 8 year old boy with fever, maculopapular rash, hepatosplenomegaly and lymphadenopathy was admitted in our institution and diagnosed with Scrub typhus. Physical and laboratory data showed hepatosplenomegaly, bicytopenia, hyperferritinemia, and hypobrinogenemia. Secondary HLH was diagnosed and the child was managed with IVIG and steroids. In view of rash followed by lymphadenopathy and hepatosplenomegaly EBV serology was also sent as a cause of HLH. Surprisingly, EBV panel was also positive. We therefore concluded that the most probable explanation was EBV triggered HPS following scrub typhus infection. Another possible explanation is EBV can be reactivated in critically ill patients. To our knowledge this is the rst such case in the pediatric population reported till date.

Seasonal abundance of Leptotrombidium deliense, the vector of scrub typhus, in areas reporting acute encephalitis syndrome in Gorakhpur district, Uttar Pradesh, India.

The rickettsial pathogen Orientia tsutsugamushi, causing scrub typhus, has been implicated as a major cause of acute encephalitis syndrome (AES) in many places in India including Gorakhpur district of Uttar Pradesh. Seasonal abundance of the principal vector mite of the pathogen, Leptotrombidium deliense, its animal hosts, and prevalence of infection on them are important attributes in the assessment of outbreaks of the disease. Hence, these aspects were investigated, seasonally, in rural villages of Gorakhpur district, where peak incidence of AES cases were reported. A total of 903 animals (rodents/shrews) was collected using 6484 Sherman traps in eight study villages (14% overall trap rate). A sum of 5526 trombiculid mites comprising 12 species was collected from 676 live rodents/shrews screened. Suncus murinus, the Asian house shrew was the predominant species (67%). Among trombiculids, the principal vector mite, L. deliense, was predominant (64.7%) and its infestation index (i.e., average number of chiggers per host animal) was 5.3. The L. deliense infestation index was higher during July to November with a peak in October. Out of 401 animal sera samples screened, 68% were positive for antibodies against O. tsutsugamushi. Of 465 blood samples tested by nested PCR, seven were positive for the 56kDa gene of O. tsutsugamushi. In conventional PCR, 41 out of 265 samples were positive for the 60kDa groEL gene of O. tsutsugamushi. Among the 5526 mite samples, tested as 352 pools through nested PCR, four pools were positive for 56kDa gene. Phylogenetic analysis of 56 and 60kDa genes confirmed circulation of Karp and TA678 (rodents) and TA678 (mite) serotypes of O. tsutsugamushi in Gorakhpur. Peak incidence of AES in Gorakhpur district occurs during the rainy season (July-October), coinciding with the peak abundance of L. deliense. These results indicate involvement of L. deliense as the vector mite transmitting the scrub typhus pathogen O. tsutsugamushi to humans in the rural areas of Gorakhpur district, India.

CLINICO-DEMOGRAPHIC PROFILE OF SCRUB TYPHUS IN UTTARAKHAND

BACKGROUND: Scrub typhus(ST) a rickettsial infection caused by Orientia tsutsugamushi and transmitted by trombiculid mites“chiggers” particularly Leptotrombidium deliense. It is one of the differential diagnoses of haemorrhagic fevers, especially if associated with acute respiratory distress syndrome and/or jaundice. A necrotic eschar at the inoculating site of the mite is pathognomic of ST.The western Himalayan regions of India, has been witnessing increased incidence of acute febrile illnesses over the years. AIM & OBJECTIVES : 1) To determine the frequency of ST in a tertiary health care hospital in Uttarakhand. 2) To understand the clinical spectrum and associated complications. 3) To analyze the demographic prole of ST cases. MATERIAL & METHODS: The retrospective study was carried out, over a period of 24 months (August 2015 to July 2017), which included cases of AFI, clinically suspected of ST. Serological testing was carried out by using commercial ELISA for specic IgM antibodies against O.tsutsugamushi. RESULTS: Out of the total 3854 cases of AFI attending the tertiary care hospital, the microbiology laboratory received a total of 760 clinically suspected cases of ST for serological testing, 494 cases (12.81%) were found positive for IgM antibodies against O.tsutsugamushi.The common symptoms noted were fever with headache, myalgias, gastrointestinal intolerance, followed by breathlessness, rash and jaundice. Eschar was seen only in 69 patients. The most common complication noticed was ARDS (8.29%) followed by hepatitis (6.88%), petechial heamorrhagic spots (38.3%) and sepsis (6.07%). Mortality rate was found to be 1.8%. The cases were mainly seen in the months between August to October which correlates the infection with the rainy season. CONCLUSION: ST should be considered as one of the differential diagnosis of AFI. Timely diagnosis and management becomes crucial to decrease/limit the diease burden, thus thwarting the onset of complications and mortality

Efficacite des bioinsecticides a base de l’huile essentielle de Cymbopogon schoenanthus (L.) spreng contre les punaises rouges (Dysdercus voelkeri, schmidt) en culture cotonniere au Togo

Currently, the fight against red bugs, a pest of the cotton plant, is limited to the use of synthetic chemical insecticides. Many of the products used are persistent and their high toxicity to human health and the environment is of concern. In the search for alternatives to synthetic chemical insecticides, the aim of this research work was to evaluate the insecticidal potential of aqueous emulsions based on the essential oil of Cymbopogon schoenanthus(L.) against Dysdercus voelkeri, one of the redoubtable pests of cotton plant in Togo. Aqueous emulsions at different concentrations were used in phytosanitary treatments on cotton crop compared to vulgarized binary insecticides (lambdacyhalothrin/profenofos 15/300 gha-1and cypermethrin/acetamiprid 36/8 gha-1). D. voelkeri counts on target plants of each elementary plot revealed that the highest dose of the emulsion (6%) of C. schoenanthus essential oil and the control (vulgarized insecticide)were more effective with low bug population densities of 7.14± 1.46 and 4.86± 1.84 bugs/plant,respectively. On the contrary,the other doses (4 and 2%) of emulsions based on C. schoenanthus essential oil had in their plots respectively 39.57 ± 5.81 and 45.28 ± 3.92 bugs/plant and the control (55.71± 5.23 bugs/plant). Health analysis of the young cotton bolls that fell under the cotton plants revealed that the highest dose of the emulsion (6%) and the control reduced stings by 71.40 and 72.33 % respectively, compared to the control. Stings reduction rates in plots with treatments of 4 and 2% of the emulsion were low with rates of 55.32and22.83%,respectively. These results clearly show that the aqueous emulsion formulated and tested in the study can significantly reduce attacks of these pests. This study shows the possibility of using the essential oil of C. schoenanthus as a raw material in the formulation of biopesticide as an alternative to synthetic chemical insecticides in the control of cotton plant red bugs in Togo.

Dysregulated neutrophils failed to control bacteria in an intradermal murine model of Orientia tsutsugamushi infection

Abstract Scrub typhus is a vector-borne febrile illness caused by the obligately intracellular bacterium, Orientia tsutsugamushi that are transmitted by the larvae of trombiculid mites. Approximately 1 million people are infected every year in an Asia-Pacific region. Patients without appropriate treatment may develop severe damage in various organs and lead to death. However, the host protective immunity against this infection is still not understood. Using an intradermal infection mouse model and CFSE-labeled bacteria, we found that neutrophils and monocytes were the majority of infected cells in the skin infection site at 4 and 8 hours post-infection (hpi). However, very few of them can migrate to local lymph node at 24 hpi. Instead, the infected langerhans cells were observed in local lymph nodes, but not in other organs including lung, bone marrow and spleen, as well as blood. To investigate the role of neutrophils in Orientia infection, we treated the infected mice with Anti-Ly6G antibody daily from −1 to 3 dpi. However, the bodyweight loss was comparable between control and neutrophil-depleted mice until 14 dpi. No significant difference of bacterial loads were found in organs including lung and brain. Our in vitro study showed that Orientia infection induced an immunosuppressive neutrophil phenotype and increased neutrophil death. Collectively, our data suggest that infected-neutrophil may undergo the functional dysregulation and not be able to control bacteria efficiently, while antigen-presenting cells may contribute to bacterial dissemination from skin to systemic infection in scrub typhus.

Screening and genotyping of Orientia tsutsugamushi from field-collected on-host chiggers (Acari: Prostigmata) recovered from a positive scrub typhus locality in Kelantan, Malaysia.

Orientia tsutsugamushi is the causative agent of scrub typhus vectored by larval stages of trombiculid mites (chiggers) that occur in most tropical regions of Southeast Asia. A total of 242 chiggers extracted from eight small mammals captured from a positive scrub typhus locality in Kelantan, Malaysia, were screened for the presence of O. tsutsugamushi. The chiggers were grouped in 16 pools for extraction of DNA prior to screening of O. tsutsugamushi based on the nucleotide sequence of 56-kDa type specific antigen (TSA) gene using nested polymerase chain reaction. Two species of on-host chiggers were identified, the one, Leptotrombidium deliense, much more dominant (94.8%) than the other, Ascoshoengastia sp. (5.2%). The pathogen was detected in two pools (12.5%) of L. deliense recovered from Rattus rattus and Tupaia sp. The 56-kDa TSA gene sequence analysis revealed the O. tsutsugamushi harboured in those chiggers were Karp prototype strain with high similarity (99.3%). Findings of this study strongly supported the existence of scrub typhus infections in certain parts of Malaysia which agrees with previous local reports. Moreover, this study highlighted the pressing need of a large-scale close observation of O. tsutsugamushi DNA sequences from chiggers that can probably be collected from other positive scrub typhus localities to precisely provide the distribution and prevalence of this zoonotic pathogen.

Targeted capture and sequencing of Orientia tsutsugamushi genomes from chiggers and humans.

Scrub typhus is a febrile disease caused by Orientia tsutsugamushi, transmitted by larval stage Trombiculid mites (chiggers), whose primary hosts are small mammals. The phylogenomics of O. tsutsugamushi in chiggers, small mammals and humans remains poorly understood. To combat the limitations imposed by the low relative quantities of pathogen DNA in typical O. tsutsugamushi clinical and ecological samples, along with the technical, safety and cost limitations of cell culture, a novel probe-based target enrichment sequencing protocol was developed. The method was designed to capture variation among conserved genes and facilitate phylogenomic analysis at the scale of population samples. A whole-genome amplification step was incorporated to enhance the efficiency of sequencing by reducing duplication rates. This resulted in on-target capture rates of up to 93% for a diverse set of human, chigger, and rodent samples, with the greatest success rate in samples with real-time PCR Ct values below 35. Analysis of the best-performing samples revealed phylogeographic clustering at local, provincial and international scales. Applying the methodology to a comprehensive set of samples could yield a more complete understanding of the ecology, genomic evolution and population structure of O. tsutsugamushi and other similarly challenging organisms, with potential benefits in the development of diagnostic tests and vaccines.

Euschoengastia pipistrelli (Acari: Trombiculidae) from American Perimyotis, Perimyotis subflavus (Chiroptera: Vespertilionidae): Novel Stereoscopic and Scanning Electron Microscopy.

The chigger, Euschoengastia pipistrelli Brennan, is a trombiculid mite that infests a variety of vespertilionid bats in North America. It has been reported from at least 9 species of bats from 18 U.S. states. However, nothing is available on the actual in situ infestation and ultrastructure of this chigger. Here we document some stereoscopic photographs of the infestation as well as a scanning electron micrograph of the mite from a common bat species. We also provide a summation of host and state records for this chigger.

A CASE SERIES ON SCRUB TYPHUS

Scrub typhus is a rickettsial disease caused by Orientia tsutsugamushi. It is transmitted to humans via infected chiggers (larva of trombiculid mite). Eschar is a characteristic feature for the diagnosis of scrub typhus and other mite or tick-borne rickettsiosis. Immunofluorescence Antibody (IFA) test is the gold standard for the diagnosis, and doxycycline is the drug of choice for treatment of scrub typhus. We present a case series of scrub typhus in three patients from South India. All three patients presented with high grade fever and IgM scrub typhus was positive status in all cases. Doxycycline 100 mg twice daily for 7 days along with supportive care was effective in all the cases. Serum creatinine levels dropped to normal and renal status of all patients improved well with antimicrobial treatment. Early diagnosis of the infection is necessary as the disease as it can have multiple system involvement and serious complications.

Co-occurrence of Eutrombicula alfreddugesi and Oswaldofilaria chabaudi in Tropidurus torquatus and first report of microfilariae in the chigger mite: possible evidence of a lifecycle pathway?

While much attention has been paid to vector-borne filariasis, diseases that threaten millions of people in tropical and subtropical countries, the literature on host-parasite associations and transmission strategies of filarial nematodes in wildlife is scarce. Here, we report the co-occurrence of chigger mites (Eutrombicula alfreddugesi) and onchocercid nematodes (Oswaldofilaria chabaudi) parasitizing the lizard Tropidurus torquatus in the State of Minas Gerais, Brazil. Examination of chiggers established, for the first time, the occurrence of microfilariae in trombiculid mites (Trombiculidae). These larvae were morphologically similar to those recovered from adult females of O. chabaudi. The current evidence suggests that chiggers do not play a role in the transmission of filarioid nematodes, but rather act as accidental or dead-end hosts. Nevertheless, considering the polyphagous nature of trombiculid mites, similar to blood-sucking insects involved in the transmission of several infectious diseases, further studies may shed light on the potential role of chiggers as vectors of filarioids.

Scrub typhus: An under-reported and emerging threat - hospital based study from central and eastern Uttar Pradesh, India.

Scrub typhus is a zoonotic rickettsial disease that is transmitted by the bite of the larval stage (chiggers) of trombiculid mites. The aim of this study was to determine the existence of scrub typhus in central and eastern Uttar Pradesh, India in patients with acute febrile illness (AFI) presenting to a super specialty tertiary level institute. This prospective hospital-based study was conducted for a period of one year, from August 2018 to July 2019. About 2-5 mL of blood samples, along with clinical, epidemiological, and demographic data from a total of 125 patients presenting with acute febrile illness to outpatient and inpatient departments, were collected. ELISA testing tested the sera from blood samples for IgM antibodies against scrub typhus. Samples were also tested for dengue, leptospirosis, malaria and typhoid. During the study period, out of a total of 125 samples collected, 20% were found positive for IgM antibodies against scrub typhus. Demographically higher positivity was found in males, older age group, and in rural area. Rainfall was found to be important epidemiological parameter for presence of scrub typhus. Co-infection with dengue, leptospirosis and malaria was found. Scrub typhus is found to be an important cause of acute febrile illness. It is necessary to include it in differential diagnosis of AFI cases even in absence of eschar. Diagnostic facilities of this as a screening test should be started in primary care centers or community health centers of rural areas of districts of central and eastern Uttar Pradesh, India.