Evidence on the prevalence of emerging and re-emerging tick- and flea-borne rickettsial agents in acute encephalitis syndrome endemic areas of northeast Uttar Pradesh, India.

Outbreaks of acute encephalitis syndrome (AES) with unknown aetiology are reported every year in Gorakhpur district, Uttar Pradesh, India, and Orientia tsutsugamushi, the rickettsial pathogen, responsible for scrub typhus has been attributed as the primary cause of AES problem. However, information on the prevalence of other rickettsial infections is lacking. Hence, this study was carried out to assess any occurrence of tick- and flea-borne rickettsial agents in villages reporting AES cases in this district. In total, 825 peridomestic small mammals were trapped, by setting 9254 Sherman traps in four villages with a trap success rate of 8.9%. The Asian house shrew, Suncus murinus, constituted the predominant animal species (56.2%) and contributed to the maximum number (87.37%) of ectoparasites. In total, 1552 ectoparasites comprising two species of ticks and one species each of flea and louse were retrieved from the trapped rodents/shrews. Rhipicephalus sanguineus, the brown dog tick, was the predominant species retrieved from the trapped rodents/shrews, and the overall infestation rate was 1.75 per animal. In total, 4428 ectoparasites comprising five tick species, three louse species and one flea species were collected from 1798 domestic animals screened. Rhipicephalus microplus was the predominant tick species collected from the domestic animals. The cat flea, Ctenocephalides felis, constituted 1.5% of the total ectoparasites. Of all the ectoparasite samples (5980) from domestic animals and rodents, tested as 1211 pools through real-time PCR assays, 64 pools were positive for 23S rRNA gene of rickettsial agents. The PCR-positive samples were subjected to multi-locus sequence typing (MLST). In BLAST and phylogenetic analysis, the ectoparasites were found to harbour Rickettsia asembonensis (n = 9), Rickettsia conorii (n = 3), Rickettsia massiliae (n = 29) and Candidatus Rickettsia senegalensis (n = 1). A total of 22 pools were detected to have multiple rickettsial agents. The prevalence of fleas and high abundance of tick vectors with natural infections of rickettsial agents indicates the risk of transmission of tick- and flea-borne rickettsial diseases in rural villages of Gorakhpur. Further epidemiological studies are required to confirm the transmission of these agents to humans.

Natural Mediterranean Spotted Fever Foci, Qingdao, China.

We sequenced DNA from spleens of rodents captured in rural areas of Qingdao, East China, during 2013-2015. We found 1 Apodemus agrarius mouse infected with Rickettsia conorii, indicating a natural Mediterranean spotted fever foci exists in East China and that the range of R. conorii could be expanding.

Serological evidence of spotted fever group rickettsiosis in and around Puducherry, south India-A three years study.

BACKGROUND & OBJECTIVES: Rickettsial diseases are important re-emerging infections that mostly go unnoticed or are misdiagnosed. Though few case reports of Indian tick typhus have been reported in Indian literature in the past 10 yr, prevalence surveys are few and far between. The objective of this research was to study the seroprevalence of spotted fever (SF) group rickettsiosis and its coinfection with scrub typhus (ST) in Puducherry region of south India, as these two diseases may show similar clinical presentations. METHODS: During 2012-2015, paired sera of 320 febrile patients were examined for Rickettsia conorii IgM/IgG by ELISA and OX19 and OX2 agglutinins by Weil-Felix test. Additionally, patients were screened for ST IgM ELISA. Statistical analysis was performed for clinical and laboratory parameters in children and adults using Fisher's exact test and chi-square test with Yates correction. RESULTS: Out of 320 patients, 142 (44.38%) had R. conorii IgM and/or IgG antibodies. Only IgM was present in 72 (22.5%) patients, while 36 patients were positive for IgG only and 34 were positive for both IgG and IgM. A total of 68 patients (21.25%) showed only OX19 and/or OX2 antibodies (titres ≥ 1 : 80). SF and ST coinfection was observed in 47 cases (14.69%). INTERPRETATION & CONCLUSION: Seroprevalence of SF in Puducherry was found to be quite high (44.38%). ST and SF coinfection was observed in 34.50% of the SG IgG positive patients, however, this require further evaluation by PCR to rule out cross-reaction or false positivity. At present ELISA seems to be an affordable alternative to highly subjective and technically demanding immunofluorescence assay (IFA) for serodiagnosis of SF.

Indian tick typhus presenting as Purpura fulminans.

Seriously ill patients presenting with purpura fulminans, sepsis and multi-organ failure often require extensive diagnostic workup for proper diagnosis and management. Host of common infections prevalent in the tropics, e.g. malaria, dengue; other septicemic infections e.g. meningococcemia, typhoid, leptospirosis, toxic shock syndrome, scarlet fever, viral exanthems like measles, infectious mononucleosis, collagen vascular diseases (Kawasaki disease, other vasculitis) diseases, and adverse drug reactions are often kept in mind, and the index of suspicion for rickettsial illness is quite low. We present a case of Indian tick typhus presenting with purpura fulminans (retiform purpura all over the body), sepsis and multiorgan failure without lymphadenopathy and eschar, successfully treated with doxycycline and discharged home. Hence, a high index clinical suspicion and prompt administration of a simple therapy has led to successful recovery of the patient.

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.

Seroprevalence of spotted fever group and typhus group rickettsiae in individuals with acute febrile illness from Gorakhpur, India.

BACKGROUND: The aim of this study was to estimate the seroprevalence of spotted fever group (SFG) and typhus group (TG) rickettsiae among individuals with acute febrile illness (AFI) in the scrub typhus endemic district of Gorakhpur in India. This district is one of the worst affected by annual seasonal acute encephalitis syndrome (AES) outbreaks. METHODS: Antibodies against SFG and TG rickettsiae and the associated risk factors were determined in 294 individuals presenting with an AFI, encountered during a community-based survey conducted during the AES outbreak period October-November 2016. RESULTS: Respective IgM and IgG seropositivity was 13.6% and 36.7% for SFG, and 7.1% and 15.3% for TG. SFG IgM positivity was significantly higher among females, while IgG positivity was significantly higher among individuals ≥45 years of age. IgM and IgG seropositivity for TG rickettsiae were significantly higher in individuals involved in outdoor activities and housewives, but did not differ according to age group, sex, or educational status. CONCLUSION: The study results present serological evidence of SFG and TG rickettsiosis, in addition to scrub typhus, among individuals with AFI in Gorakhpur region and indicate the need to explore their roles as potential causes of AES in the region.

Indian Tick Typhus Presenting as Purpura Fulminans with Review on Rickettsial Infections.

Rickettsial diseases are some of the most covert reemerging infections of the present times. They are generally incapacitating and notoriously difficult to diagnose; untreated cases can have fatality rates as high as 30%-35%, but when diagnosed properly, they are often easily treated but lack of definite diagnostic tools and the hazards of handling these microorganisms aggravate the difficulties of diagnosis and treatment.

Indian tick typhus - an uncommon cause of hepatitis: a case report.

Although viruses remain the most common cause of hepatitis, other causes like rickettsial hepatitis are also well known. However, this aetiology has not been well recognized and it has been rarely reported in the Indian literature. Here, we are discussing a case of acute hepatitis, its clinical presentation, diagnosis and treatment, which was later found to be caused by Indian tick typhus (a spotted fever group rickettsia), which was diagnosed on the basis of serology and its clinical response to doxycycline. Further literature review has been done, to discuss various clinical presentations and prevalence of rickettsial infection in this part of the world.