July 8, 2022

SCRUB TYPHUS: FOCUSED DIAGNOSIS

Scrub typhus is an infectious, acute, febrile disease. The illness was first observed and described in China in 313 AD.

It was first isolated in Japan in 1930 when severe epidemics of the disease occurred among troops in Burma and Ceylon during World War II and the India-Pakistan war in 1965.

The infection is primarily found in South East Asia & the islands of the Western Pacific. In India, Scrub typhus came into the public eye after an epidemic in Assam and West Bengal during the Second World War. It resurfaced in 2003-04 and 2007 with outbreaks in Himachal Pradesh, Sikkim, and Darjeeling. However, the largest outbreak so far happened in Uttarakhand in 2012. According to the Indian government’s National Centre for Disease Control’s annual report for 2016-17, there were 40 outbreaks of scrub typhus between 2008 and 2017 in various states across India.

Scrub typhus (ST) is a mite-borne or zoonotic infection, a disease caused by bacteria called Orientia tsutsugamushi. It belongs to the family Rickettsiaceae and is transmitted to humans by biting a larval trombiculid mite or chigger. The most familiar symptoms of scrub typhus are not limited to but include fever, headache, and body aches and may continue as such, thus being mistaken for other acute infections such as Dengue, Malaria, Chikungunya, or typhoid.

The differentiating clinical sign is a cigarette burn-like sore, called an eschar, which develops at the site of infection, usually in the armpits, groin, or abdominal region, and does not cause pain or itching. Therefore Eschar escapes detection in many patients because of the variability in the thoroughness of physical examinations and immunological factors.

The Major Health Problems associated with Scrub Typhus are interstitial pneumonia leading to ARDS (Acute Respiratory Distress Syndrome), Renal failure, Septic shock, Jaundice, Meningoencephalitis & Myocarditis. If not treated timely or in the case of delayed diagnosis, the infection can result in multi-organ failure, ultimately leading to death. In the Indian scenario, studies have shown a significantly high incidence of Fatality – going up to 14% when presented with Complications.

As per data from 90 studies of scrub typhus (ST) infection, there were multiple organ dysfunction syndromes in 17.4% of cases, 20.4% of patients required ICU admission, and 19.1% needed ventilation. In addition, the overall case-fatality rate was 6.3%. The mortality with those with multi-organ dysfunction syndrome was as high as 38.9%.

The ST diagnosis is usually suggested by the clinical history and physical findings and confirmed by serologic testing or biopsy of an eschar. Several methods; Weil-Felix test, Enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), immunochromatographic test (ICT), polymerase chain reaction (PCR), and loop-mediated isothermal amplification (LAMP are effectual for diagnosis of scrub typhus.

Though the Weil-Felix test is the most commonly performed test despite its low sensitivity & specificity, Immuno-based Serological methods like IFA and ELISA are most preferred for detecting scrub typhus due to their higher sensitivity and specificity.

The Elisa test based on detecting IgM antibodies to Scrub typhus is the best diagnostic method with higher sensitivity and specificity. In addition, batch processing of samples can result in a quick turnaround ( less than 2 hours) when working with the Elisa method.

Quick diagnosis and prompt treatment can significantly reduce complications and mortality. Therefore, establishing good surveillance and instituting appropriate control measures are urgently needed.

J. Mitra has taken a lead role and focused on diagnosing Scrub typhus in India. Both Rapid; SCRUB TYPHUS (TSUTSUGAMUSHI) IgM & IgG CARD (ICT), SCRUB TYPHUS IgM Quanti Card (IFA) & SCRUB TYPHUS IgM MICROLISA( ELISA) products are available to cater different customers need.

All three products are indigenously developed, have a user-friendly procedure, and have high precision and accuracy in test results concerning sensitivity and specificity.

Awareness of Scrub Typhus among the populace, combined with a timely and accurate diagnosis, can reduce the impact of this deadly Killer Disease. Furthermore, increasing focus on Monitoring and surveillance of Scrub Typhus among the Medical Fraternity at primary and secondary health care centers would also improve the chances of an Accurate Diagnosis followed by Treatment of Scrub Typhus.

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