ABSTRACT
Background: Scrub typhus infection is endemic in India and reported to be the major cause for acute encephalitis syndrome (AES) in humans. Periodic occurrence of scrub typhus cases and presence of pathogen in rodents were also reported in areas with human cases of scrub typhus in Puducherry. Objectives: This study was carried out to screen Orientia tsutsugamushi in rodent/shrew reservoirs and vectors in villages of Puducherry with no reports of human scrub typhus cases. Methods: This study was conducted during October 2017 to January 2018 in ten randomly selected villages in Puducherry. Rodents/shrews in the peridomestic area were trapped using Sherman traps. Screening of O. tsutsugamushi in rodents/shrews and mite vectors was done by polymerase chain reaction (PCR). Weil-Felix test was done to screen antibodies against O. tsutsugamushi in rodent serum samples. Results: Among the 54 rodents trapped, Suncus murinus was the major small animal and Leptotrombidium deliense was the major mite species retrieved. PCR screening revealed pathogen positivity in 8 rodent blood and 3 pooled mite samples. Phylogenetic analysis has shown that Kato was the circulating serotype of O. tsutsugamushi. None of the rodent serum samples was tested positive for antibodies against O. tsutsugamushi by Weil-Felix test. Conclusions: The presence of pathogen in both vectors and reservoir animal hosts imposes a risk for scrub typhus transmission to the inhabitants; hence, initiation of vector control measures before the start of winter is recommended in the study area. It is also recommended to screen scrub typhus in patients with undifferentiated acute febrile illness and AES.
ABSTRACT
Background & objectives: Genetic aberrations disrupting toll-like receptor and interferon homeostasis enhance the risk of systemic lupus erythematosus (SLE). Raised serum interferon-alpha (IFN-?) levels in SLE patients have been ascribed to polymorphism (rs2004640 G/T) in interferon regulatory factor 5 (IRF5) gene, resulting in enhanced transcript splicing. A positive association between IRF5 polymorphism and SLE risk has been reported in many populations. This study was aimed to find out frequency of IRF5 rs2004640 G/T polymorphism in patients with SLE and healthy controls and to assess its influence on susceptibility, clinical and serological characteristics of SLE. Methods: IRF5 rs2004640 (G/T) polymorphism was analyzed in 300 SLE patients and 460 age and sex matched controls by real-time PCR. Results: The IRF5 rs2004640 (G/T) polymorphism did not confer risk of SLE or influence clinical or serological phenotype. However, the mutant allele conferred a borderline risk to develop thrombocytopenia (odds ratio: 2.05, 95% confidence interval: 0.97�3, P=0.06) in patients with SLE. Interpretation & conclusions: Our study revealed that the IRF5 rs2004640 polymorphism was not a risk factor for SLE in population from south India. It may, however, be a useful genetic marker for thrombocytopenia in SLE patients. Although we could not demonstrate susceptibility toward lupus in the presence of IRF5 rs2004640 (G/T) polymorphism, further exploration of the genetic variability of IRF5 may help uncover its pathogenic role in Indian SLE patients.