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Scrub Typhus — Scientific Neglect, Ever-Widening Impact

Scrub typhus, a systemic, life-threatening disease with an enormous incidence in Asia and the islands of the Pacific and Indian Oceans, remains remarkably neglected. Discovery of this vectorborne infectious disease on Chiloé Island in Chile and its detection in Africa highlight the fact that we have heretofore paid too little attention to it and developed too little relevant expertise. The Allied armies were caught flat-footed during World War II when 18,000 of their troops became ill with scrub typhus in the Pacific theater, and the disease remained a major cause of severe, undifferentiated febrile illness in U.S. military forces in Vietnam. Currently, there is a tremendous widespread reemergence…

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 Neglected scrub typhus

Scrub typhus is one of the neglected, underreported, and underdiagnosed febrile disease requiring comprehensive investigations to curb the infection. Since the last decade, incidences of scrub typhus outbreaks have increased, which makes it a public health concern of significant importance.

 Unwelcome Surprise: A Disease-Spreading Chigger Turns Up In Chile

Nobody wants to be attacked by a chigger. These six-legged mite larvae — so small they're invisible to the naked eye — have a powerful bite that causes severe itching. They also transmit a disease called scrub typhus, named for the forest undergrowth, or scrub, that is home to the chiggers.

Articles of Interest

About Scrub Typhus

Scrub typhus, also known as bush typhus, is a disease caused by bacteria called Orientia tsutsugamushi. Scrub typhus is spread to people through bites of infected chiggers (larval mites). The most common symptoms of scrub typhus include fever, headache, body aches, and rash.

Eschar: A Stepping Stone to Scrub Typhus

The presence of eschar is highly diagnostic and serves as a stepping stone to scrub typhus and provides a clue for early successful empirical treatment.mEschar is noted in 40%-60% of patients, and the location is commonly covered by clothes.

Global seroprevalence of scrub typhus: a systematic review and meta-analysis

Scrub typhus, a neglected disease, is a significant health concern in the Tsutsugamushi triangle of the Asia–Pacific and has raised global concerns due to recent cases occurring outside this region.

India Must Pay More Attention to Silent Killer Scrub Typhus

While scrub typhus is curable, it is also dangerous if it festers too long. When undetected, its mortality rate is around 13 percent. Owing to poor awareness, and due to the fact that both of them occur during the same seasons, many people mistake scrub typhus for dengue and end up mistreating it.

Resurgence of scrub typhus fever

Because of unique characteristics of mites and chiggers, and as chiggers can only stay within few metres of the the place where they hatch, there is formation of highly focal “islands of infection” in affected areas.

Scrub typhus – a neglected disease

The clinical and laboratory features of scrub typhus are notoriously nonspecific. Physicians often misinterpret early clinical signs, although clinical diagnosis has improved markedly over the last 30 years (see lecture notes from George Lewis). The single most useful diagnostic clue is the eschar, but this may appear in only about 50% of infected individuals. Like many infectious diseases, the early recorded history of scrub typhus is somewhat sketchy, although some early accounts appear to describe the disease. What was possibly the earliest published account of scrub typhus was from the Ming Dynasty in China during the 3rd century A.D.

Scrub typhus-resurgence of a forgotten killer

These cases are increasingly seen all over and are treated as either enteric/Gram-negative sepsis or malaria. Rampant misuse of antibiotics, which have activity against typhus, has also added to the confusion. Absence of eschar or rash should not lead to its exclusion from differential diagnosis. A high index of suspicion, effective and prompt treatment can save lives.

Scrub Typhus: An Emerging Threat

Scrub typhus, first described in Japan in 1899, caused by Orientia tsutsugamushi (formerly Rickettsia), is an acute infectious disease of variable severity that is transmitted to humans by an arthropod vector of the Trombiculidae family. It affects people of all ages including children. Humans are accidental hosts in this zoonotic disease. While scrub typhus is confined geographically to the Asia Pacific region, a billion people are at risk and nearly a million cases are reported every year. Tetracycline or chloramphenicol remains the main stay of therapy.

Scrub Typhus: An Overview

When an infected chigger initially bites, it is often painless and goes unnoticed. However, within a few hours, itching and the appearance of a small, reddish welt or sore around the bite occur. The incubation period for the bacteria within the body is approximately 6-10 days, with symptoms typically emerging around 10-12 days after the bite.

Scrub typhus: Clinical spectrum and outcome

Scrub typhus is one of the differential diagnoses for fever with thrombocytopenia. ARDS associated with Scrub typhus has high morbidity and mortality.

Scrub Typhus: Historic Perspective and Current Status of the Worldwide Presence of Orientia Species

Scrub typhus and its etiological agents, Orientia species, have been around for a very long time. Historical reference to the rickettsial disease scrub typhus was first described in China (313 AD) by Hong Ge in a clinical manual (Zhouhofang) and in Japan (1810 AD) when Hakuju Hashimoto described tsutsuga, a noxious harmful disease in the Niigata prefecture.

Scrub typhus: Overview, Pathogenesis and Lab Diagnosis

Tetracyclines (doxycycline) and chloramphenicol are drugs of choice and are effective in both oral and intravenous forms against scrub typhus. Azithromycin is also an excellent alternative, particularly when resistance to doxycycline is suspected.

StatPearls

Scrub typhus is a severe infectious disease caused by the rickettsial bacterium Orientia tsutsugamushi, presenting a significant public health concern in the Asia-Pacific region, especially within the "tsutsugamushi triangle." Spanning over 8 million square kilometers and affecting more than 1 billion people across countries such as Pakistan in the west, Australia in the south, and Japan in the east, this triangular area poses a significant public health threat with a high risk of fatality.