Two cases of scrub typhus have been reported from Noida. These are the first cases to be reported in six years. The two patients, a 14-year-old girl and a 56-year-old woman, were hospitalized with complaints of high fever and rashes. Since then, the health department is conducting surveillance of cases with febrile illness to detect more cases. Cases of scrub typhus have also been reported from other districts of UP mainly from Firozabad, Agra, Mainpuri, Etah and Kasganj.

Scrub typhus was first identified from Japan in late 19^th century. Globally, it is endemic in an area which extends from northern Japan and far-eastern Russia in the north, to northern Australia in the south, and to Pakistan in the west, which has been called the “tsutsugamushi triangle”. But it has also been reported from outside of this delineated area.

Scrub typhus is a re-emerging zoonotic disease in India. It is particularly prevalent in the sub-Himalayan belt.  However, it has also been reported from Delhi, Haryana, Rajasthan, Maharashtra, Uttarakhand, Chhattisgarh, Tamil Nadu and Kerala. Outbreaks are frequent during the rainy season.

Scrub typhus resembles other common monsoon fevers such as dengue, malaria, chikungunya, especially when there is no eschar. A clinical diagnosis is difficult. It is therefore grouped as acute undifferentiated fever with its several etiologies. Like dengue and Chikungunya, scrub typhus too is a notifiable disease, but unlike dengue and chikungunya, if scrub typhus is not treated on time with antibiotics, it can be fatal.

Here are some key points about scrub typhus.

• Scrub typhus is a rickettsial infection caused by Orientia tsutsugamushi, which was earlier known as Rickettsia tsutsugamushi.
• It is also called Tsutsugamushi disease or Bush typhus or Chigger borne typhus.
• The reservoir of infection is the trombiculid mite, which is also the vector for the infection. Humans are accidental hosts and get infected through the bite of the infected larva (chigger) while walking through the bush area or sitting or lying down on the infested ground. No human-to-human transmission has been reported.
• Incubation period: 10-12 days.
• Clinical presentation: varies from mild, self-limiting disease to a fatal infection with multiorgan failure if not managed in time. Mortality rate can be as high as 50%.
• Common symptoms: Non-specific; high fever and chills, headache, malaise, myalgia, cough, breathlessness, diarrhea, vomiting and maculopapular rash, which is nonpruritic. The rash typically begins on the abdomen and spreads to the extremities.
• Pathognomonic sign: A characteristic eschar at the site of chigger bite, which appears as an ulcer area with a black necrotic center (resembling the mark of a cigarette burn) and an erythematous border gives a clue for the diagnosis. The single eschar is usually located on the exposed body parts like legs, neck, axilla, chest, abdomen and groin along with regional lymph node enlargement. The eschar appears few days after the chigger bite, but before the disease manifests clinically. Hence, fever patients should be thoroughly examined. The eschar in the intertriginous areas is seen as shallow yellow based ulcer without surrounding hyperemia and no black scab; hence, may be overlooked.
• Case definition (ICMR)
• Definition of suspected/clinical case: Acute undifferentiated febrile illness of ≥5 days with or without eschar should be suspected as a case of Rickettsial infection (If eschar is present, fever of <5 days duration should be considered as scrub typhus). Other presenting features may be headache and rash, lymphadenopathy, multi-organ involvement like liver, lung and kidney involvement.
• Definition of probable case: A suspected clinical case showing titres of ≥1:80 in OX2, OX19 and OXK antigens by Weil Felix test and an optical density (OD) > 0.5 for IgM by ELISA are considered positive for typhus and spotted fever groups of Rickettsiae.
• Definition of confirmed case: A confirmed case is the one in which: Rickettsial DNA is detected in eschar samples or whole blood by PCR or rising antibody titers on acute and convalescent sera detected by IFA or Indirect Immunoperoxidase Assay (IPA)
• Complications: Jaundice, renal failure, pneumonitis, acute respiratory distress syndrome (ARDS), septic shock, myocarditis, meningoencephalitis
• Coinfections with dengue, leptospirosis, malaria have been reported. Scrub typhus may co-exist with COVID-19.
• Differential diagnosis: Other febrile illnesses like dengue fever, malaria, chikungunya, leptospirosis, pneumonia, typhoid
• Laboratory tests: mandatory to confirm diagnosis. Detection of IgM antibody on ELISA (positive within 3-4 days after the onset of illness), Weil Felix reaction (IgM titer ≥ 1:320 or a 4-fold rise in titer starting from 1:50), PCR from blood and eschar. Weil Felix test may be negative early in the infection as IgM antibodies appear only during the 2nd week. Immunofluorescence assay (IFA) is the gold standard serological test; but the cost and need for specialized lab deter its routine use.
• Treatment: Start antibiotics as soon as scrub typhus is suspected. Doxycycline is the antibiotic of choice (200 mg / day in two divided doses for individuals above 45 kg x 7 days, orally or IV). Alternatively, azithromycin 500 mg single dose for 5 days (orally or IV), or tetracycline 500 mg in 4 divided doses for 7 days (orally or IV) can be used. In pregnant women since doxycycline is contraindicated, azithromycin 500 mg in a single dose for 5 days is preferred.
• Response to antibiotics is prompt with patients typically becoming afebrile within 48 hours of starting antibiotics. This response to treatment is useful in diagnosis as failure of defervescence within 48 hours practically rules out scrub typhus.
• Prevention: Chemoprophylaxis in endemic areas (single dose weekly doxycycline 200 mg, started before exposure to 6 weeks after exposure) and mite control (clearing the vegetation, application of insecticides to the ground and vegetation, application of insect repellents and miticide to both the exposed skin and clothing). Other preventive measures included long sleeved clothing, applying mite repellents to exposed skin and avoid traveling to places where the infection is endemic.
• There is current no vaccine for scrub typhus.