Molecular characterization of Orientia tsutsugamushi causing fatal scrub typhus in a young male affected by so-called "mystery fever" in North India.

Scrub typhus is a zoonotic disease caused by Orientia tsutsugamushi. Although the presence of eschar is considered pathognomic, diagnosis of scrub typhus is challenging due to overlapping presentation. The diagnosis is based on the serological and molecular assay. Here, we describe a case of a young male patient who was diagnosed with scrub typhus and developed complications in the course of the disease. We also performed molecular characterization of the strain which revealed a close relatedness to Karp-like Linh.DT strains were previously reported from Vietnam.

First detection and genetic identification of Rickettsia spp. from ticks collected from rodents in north India.

BACKGROUND: Changing climatic conditions and invasion of ticks in urban areas have led to a greater number of cases of tick-borne diseases, thus, becoming a matter of increasing concern. Tick borne rickettsioses are one of the important emerging diseases worldwide. Knowledge of epidemiology of the vector and pathogen in the community is essential in order to understand and prevent the transmission of the disease to healthy population. METHODS: In our present study, we trapped rodents in selected areas of Chandigarh and Punjab in north India. The rodents were screened for the presence of ticks which were further screened for the presence of rickettsial agents. PCRs targeting 17 â€‹kDa and gltA genes were carried out followed by Sanger sequencing of the positive amplicons followed by phylogenetic analysis of the sequences. RESULTS: A total of 17 ticks were collected out of which one (Rhipicephalus sanguineus) was found to be harboring a Rickettsia sp. PCR targeting gltA and 17 â€‹kDa genes of rickettsia were put up and Sanger sequencing was performed. Phylogenetic analysis revealed the sequences to be closely related to Rickettsia rhipicephali. CONCLUSION: The current study establishes the presence of rickettsial agents in the community. Although Rickettsia rhipicephali is a non-pathogenic agent, the study encourages more vigorous community surveillance should be carried out in order to determine the exact burden of rickettsial agents in our community. To our knowledge, this is the first study reporting Rickettsia rhipicephali in India.

A Review of Rickettsial Diseases Other Than Scrub Typhus in India.

Rickettsial diseases (RD) are widely reported all over the world. Scrub typhus (ST) is a major tropical infection which is well documented all over India. Therefore, the index of suspicion of scrub typhus is high among physicians with regard to patients presenting with acute febrile illness (AFI) and acute undifferentiated febrile illness (AUFI) in India. Rickettsial diseases other than ST (non-ST RDs), which include spotted fever group (SFG) rickettsioses and typhus group (TG) rickettsioses are not uncommon in India, but the index of suspicion is not as high as ST unless there is a history of the presence of fever with rashes and/or recent arthropod bites. This review aims to look into the Indian scenario on the epidemiology of non-ST RDs, especially the SFG and TG rickettsioses based on various investigations, spectrum of clinical presentation, challenges and gaps in knowledge to suspect and diagnose these infections.

Rickettsia conorii infection with fatal complication.

Rickettsial diseases (RD) are a group of endotheliotropic infectious diseases caused by different species of genera Rickettsia. RD are not an uncommon disease and may be misdiagnosed during the evaluation of acute febrile illness due to a lack of reliable serological marker and diagnostic culture methods. Clinical manifestation of RD varies from febrile illness with rashes and myalgia to fatal complications such as shock and respiratory failure. We describe a case of a young male who presented initially with acute febrile illness, followed by shock and respiratory failure, and unfortunately succumbed to death. A post-mortem examination showed histological features of endotheliotropic infection, such as interstitial / perivascular edema in various organs and noncardiogenic pulmonary edema (suggesting increased vascular permeability) and evidence of vasculitis in the lung, liver, and intestines. Molecular studies performed from lung, liver, and kidney tissue confirm the diagnosis of spotted fever group rickettsial disease due to Rickettsia conorii.

Vector and rodent surveillance for Orientia tsutsugamushi in north India.

BACKGROUND & OBJECTIVES: Scrub typhus or chigger borne typhus, caused by Orientia tsutsugamushi is an emerging vector-borne disease as large numbers of cases have been reported in various tropical countries. It is transmitted to humans through bites of infected chiggers (larval mites). The knowledge about the vector, its distribution, density and habitat are important so as to understand the epidemiology of scrub typhus in a given area. To control rickettsial infections, regular rodent-vector surveillance should be planned in areas where the disease transmission is occurring and it will also help to strengthen the existing entomological data related to the vector of scrub typhus in northern India. METHODS: In the present study, rodent-vector surveillance was planned for one whole year, covering both mite active and non-active seasons (October 2019-December 2020) in selected areas of Chandigarh and Punjab in north India. Rodent tissues and mites were also examined for the presence of O. tsutsugamushi by nested PCR for 56 kDa gene and real-time PCR for 47 kDa outer membrane protein gene. 18S gene PCR was performed for molecular identification of mites. RESULTS: In the surveillance, three types of ectoparasite, viz. mites, fleas and ticks were obtained in rodents. All mites found were of Laelapidae family. None of the pooled rodent tissue samples as well as mite samples were found positive for O. tsutsugamushi by nested PCR for rickettsial DNA. INTERPRETATION & CONCLUSION: In the present study, we did not get any evidence of carriage of O. tsutsugamushi in either mites or rodents collected and sampled in selected regions in Chandigarh and Punjab. We need to strengthen the entomological surveillance over a broader region and increase the frequency of trapping rodents to increase clarity on vector-reservoir dynamics in this geographical region.

Rickettsia conorii infection with fatal complication

ABSTRACT Rickettsial diseases (RD) are a group of endotheliotropic infectious diseases caused by different species of genera Rickettsia. RD are not an uncommon disease and may be misdiagnosed during the evaluation of acute febrile illness due to a lack of reliable serological marker and diagnostic culture methods. Clinical manifestation of RD varies from febrile illness with rashes and myalgia to fatal complications such as shock and respiratory failure. We describe a case of a young male who presented initially with acute febrile illness, followed by shock and respiratory failure, and unfortunately succumbed to death. A post-mortem examination showed histological features of endotheliotropic infection, such as interstitial / perivascular edema in various organs and noncardiogenic pulmonary edema (suggesting increased vascular permeability) and evidence of vasculitis in the lung, liver, and intestines. Molecular studies performed from lung, liver, and kidney tissue confirm the diagnosis of spotted fever group rickettsial disease due to Rickettsia conorii.