Treatment Of Scrub Typhus

Introduction

Scrub typhus, also known as bush typhus or tsutsugamushi disease, is an acute febrile bacterial infection caused by the gram-negative bacteria Orientia tsutsugamushi.
The name “scrub” in scrub typhus refers to the vegetation harboring the vector (terrain between woods and clearings). Scrub typhus is an acute febrile fever that can cause significant morbidity and mortality if left untreated.

Causative Organism

Orientia tsutsugamushi, a Gram-negative bacteria found in the endemic regions from the Rickettsiaceae family, is the causative agent for scrub typhus. It’s an intracellular pathogen carried by mites called Leptotrombidium, also known as a chigger. It is mainly found in rural parts of Southeast Asia, China, Japan, India, and northern Australia. They are connected with specific habitats like abandoned plantations, shrubby areas at the edges of woods and fields, gardens or rice fields, overgrown forest clearings, riverbanks, and grassy fields.

This bacterium causes complications in the central nervous system, cardiovascular system, respiratory system, renal system, and gastrointestinal system.

Mode of transmission

Scrub Typhus disease is transmitted to humans through the bite of an infected chigger. The mite’s bite creates a distinctive black eschar that helps the doctor diagnose the condition.
Adult mites go through four stages of development: egg, larva, nymph, and adult. Because the other life stages (nymph and adult) do not feed on vertebrate animals. Only the larva (chigger) can transmit the disease to humans and other vertebrates. In the soil, both the nymph and the adult live free.

What is the incubation period for Scrub Typhus?

Scrub typhus takes 5 to 20 days (on average, 10-12 days) to develop after being bitten by a chigger (larva of the mite).

Clinical features of Scrub Typhus

The bite of a chigger is painless and may manifest as a localized irritation. Bites on the crotch, axillae, genitalia, and neck are common. Humans frequently develop an eschar at the site of a chigger bite. Shaking chills, fever, severe headache, inflammation of the mucous membrane lining the eyes (conjunctivitis), and swelling of the lymph nodes are all symptoms that appear rapidly. In addition, there could be a speckled rash on the trunk. Muscle and stomach discomfort are common symptoms.

Treatment Of Scrub Typhus
The primary stage treatment is towards the uncomplicated cases; it should involve:

• Recognition of disease severity: – If a patient presents with complications to a primary health facility and the treating physician suspects O. tsutsugamushi infection, doxycycline treatment should be started before the patient is referred to further test or medication.
• In the event of complications such as ARDS (adult respiratory distress syndrome-like presentation, myocarditis, and disseminated intravascular coagulation), acute renal failure, meningoencephalitis, or multi-organ dysfunction, a referral to a secondary or tertiary center is made. When scrub typhus is suspected, doxycycline should be started in addition to the usual treatment for community-acquired pneumonia.

When scrub typhus is suspected in fever cases lasting five days or more and malaria, dengue, and typhoid have tested negative; the following medications should be taken:

Adults

Doxycycline 200 mg every day, divided into two doses for seven days for individuals weighing more than 45 kg.

Or

Azithromycin strength 500 mg once a day for five consecutive days.

Children

Doxycycline in the dose of 4.5 mg/kg body weight/day in two divided doses for children below 45 kg

Or

Azithromycin in the single dose of 10mg/kg body weight for five days.

Pregnant women

Azithromycin 500 mg/ day for five days should be administered. Azithromycin is the drug of choice for scrub typhus in pregnant women.

The safety of Azithromycin in pregnant women and children is the most crucial benefit of utilizing it in clinical practice. Scrub typhus complicating pregnancy is unusual, but it can have devastating consequences for both the mother and the fetus if it does occur. Azithromycin is a medication in pregnant women that is safe for both mothers and fetuses.

Secondary stage treatment
The secondary stage treatment is for the complicated cases; the treatment involves:
Intravenous doxycycline 100mg twice daily in 100 ml normal saline to be administered as an infusion over half an hour initially followed by an oral dose for 7-15 days of complete therapy.

OR

Intravenous Azithromycin [500mg IV in 250 ml normal saline over 1 hour once daily for 1-2 days followed by oral therapy to complete five days of treatment]

OR

Intravenous chloramphenicol [50-100 mg/kg/d six hourly doses to be administered as an infusion over one hour initially followed by oral therapy to complete 7-15 days of treatment]

Cases of Doxycycline and Chloramphenicol resistant strains are sensitive to Azithromycin.

Prevention of Scrub Typhus

As the adage goes- “Prevention is better than cure,” it’s vital to bear in mind the various preventive strategies for Scrub Typhus. Unfortunately, there is no licensed vaccine developed for scrub typhus at present. In other words, the main aim should be to avoid the chigger bites with the help of the below-listed strategy:

• Use a topical insect repellent containing DEET (N, N-Diethyl-m-toluamide) to skin with permethrin-treated clothes.
• Scrub typhus can also be prevented with a weekly dose of 200 mg doxycycline.
• Basic hygiene is beneficial. Simple activities like showering at least once a week and changing & washing your clothes are part of clean hygiene.
• Keep a safe distance from typhus-carrying wild animals such as rats, flying squirrels, and opossums.
• Keep your surrounding neat and clean. Do not throw trash on the road pr dump garbage in the open.

REFERENCE

1. A brief guide to emerging infectious diseases and zoonoses. Available from: https://apps.who.int/iris/rest/bitstreams/909329/retrieve
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