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EXPLAINED: What Is Scrub Typhus, Which Is Fuelling Worries Amid Rising Fever Deaths In UP

Western UP is facing a dengue outbreak with experts saying some cases of scrub typhus have been detected

Western UP is facing a dengue outbreak with experts saying some cases of scrub typhus have been detected

It is a bacterial infection caused by tiny insects called mites and needs early diagnosis. Here' s all you need to know about scrub typhus

More than 100 deaths due to fever have health authorities on their toes in western UP. While the majority of cases have been attributed to a dengue outbreak, officials have said isolated cases of scrub typhus, too, have been detected in the region with at least two patients having been diagnosed with the disease in Noida.

What Is Scrub Typhus?

It is a disease that is caused as a result of being bitten by tiny insects known as mites. The bacteria causing the disease is known as Orientia tsutsugamushi, the name deriving from the Japanese words ‘tsutsuga’, meaning dangerous, and ‘mushi’, or insect. The disease is also known as bush typhus, tsutsugamushi disease or chigger- borne typhus and was earlier called Rickettsia. A chigger is defined as a “tropical flea, the female of which burrows and lays eggs beneath the host’s skin, causing painful sores".

According to the National Health Portal (NHP), scrub typhus is a zoonotic disease and “humans are accidental hosts in this disease".

What Are The Symptoms?

The US Centres for Disease Control and Prevention (CDC) says that the “most common symptoms of scrub typhus include fever, headache, body aches, and sometimes rash" while NHP describes it as an “acute, febrile, infectious illness".

The National Centre for Disease Control (NCDC), which sent a team of experts to UP following reports of emergence of scrub typhus cases, says that the incubation period for the disease is 1-3 weeks though the US CDC advises that “symptoms of scrub typhus usually begin within 10 days of being bitten". The disease can cause chills and muscle pain and also lead to the formation of a “dark, scab-like region at the site of the chigger bite". It can lead to mental changes, ranging from confusion to coma and “people with severe illness may develop organ failure and bleeding, which can be fatal if left untreated".

A 2017 paper in the Indian Journal of Dermatology (IJD) said that mortality rates for scrub typhus range from less than 1 per cent to 50 per cent “depending on proper antibiotic treatment, status of the individual infected, and the strain of Orientia tsutsugamushi encountered".

How Do Humans Pick Up The Disease?

The vector mites most closely associated with scrub typhus are commonly found in forested areas and in areas of “secondary vegetation after clearance of forest areas", NCDC says, adding that the insect is “generally abundant on

grasses and herbs where bushes are scarce". Researchers say that infection takes place when humans accidentally pick up an infective larval mite “while walking, sitting, or lying on the infested ground".

Locations like forest clearings, riverbanks, and grassy regions are said to “provide optimal conditions for the infected mites to thrive".

Where Is It Prevalent?

The IJD paper said that more than 1 billion people globally are “at risk for scrub typhus and an estimated one million cases occur annually". Given that the disease is common to areas of sandy beaches, mountain deserts, and equatorial rain forests, there is a wide swathe of territory where people are vulnerable to scrub typhus.

The disease is largely prevalent in southeast and east Asia with cases occurring in India, Pakistan, Indonesia, the Maldives, Myanmar, Nepal, Sri Lanka, Thailand and other islands in the region.

Scrub typhus has been described as “a reemerging infectious disease in India" and is prevalent across the country. Outbreaks have been reported in the sub-Himalayan belt from Jammu to Nagaland as also in Rajasthan. Scrub typhus outbreaks occurred in Himanchal Pradesh, Sikkim and northern West Bengal during 2003-2004 and 2007.

“Outbreak occurs more frequently during the rainy season, however, in southern India, outbreaks are reported during the cooler months of the year," NHP said.

How Is It Diagnosed? What Are The Treatments?

The US CDC notes that scrub typhus symptoms are similar to those caused by many other diseases. It, therefore, recommends seeking medical help if one has developed symptoms after moving in areas where scrub typhus is found.

NCDC says that scrub typhus may be diagnosed in the laboratory by, among other things, serology, or blood, tests and PCR tests. In India, scrub typhus is a notifiable disease, which means that medical practitioners are mandated to inform public health authorities if they encounter any cases of the disease.

No vaccines exist against scrub typhus and the disease, the US CDC says, “should be treated with the antibiotic doxycycline". It says that doxycycline “can be used in persons of any age", adding that “antibiotics are most effective if given soon after symptoms begin".

How To Prevent The Occurrence Of Scrub Typhus?

NCDC says that spraying insecticide in areas that may house the vector mites, reducing rodent populations and destroying limited amounts of local vegetation can be helpful in preventing outbreaks. It further recommends that those who need to venture into areas that may be infested with such mites to wear protective clothing and “impregnate their clothing and bedding with a mitecide (like benzyl benzoate) and apply a mite repellent… to exposed skin".

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first published:September 08, 2021, 18:42 IST