Re-emerging scrub typhus in India- How to diagnose?
M3 India Newsdesk Mar 31, 2019
Scrub typhus or Bush typhus is re-emerging as a major threat in India, making it crucial for increasing awareness on the vector-borne bacterial disease, whose symptoms can easily be confused with that of malaria or typhoid.
Scrub typhus, also known as bush typhus, is a potentially fatal disease endemic to certain parts of India. In the north-eastern state of Mizoram alone, it has claimed more than 100 lives and infected 900 since it was first detected there in 2012. And the healthcare industry is yet to come up with an antidote for the disease.
Vector Transmission
The infected mite larvae (chiggers) that transmit the infection to humans are usually found in forests, marshlands, bushy areas, grasslands, gardens, beaches and wood heaps. These chiggers feed on forests and rural rodents such as, rats, voles and field mice.
Causative Agent
The causative bacterium behind this fatal disease is Orientia Tsutsugamushi, an intracellular pathogen that infects cells in the body to multiply. This bacterium is known to be highly virulent and should only be handled in a medical laboratory with highly safe facilities.
Other Modes of Transmission
Besides mites, unclean needles and unscreened blood transfusion can also facilitate the spread of scrub typhus.
Key symptoms
When the bacterium infects a human being, the symptoms usually begin to appear within six to 20 days. Symptoms include:
- Chills
- Sweating
- Fever
- Rashes
- Lymph node swelling
- Muscle pain
- Headache
The chigger bite causes redness on the skin with a black shell, called eschar. Usually, the initial lesion of scrub typhus is about 1 cm in diameter. It tends to vesiculate and finally rupture, resulting in enlargement of regional lymph nodes. If these symptoms are left untreated, the infection can soar and manifest in the form of jaundice, pneumonia, multi-organ failure, paralysis, or hemorrhage, any of which could cause death.
During the first week of fever, the body temperatures may rise to 104-105°F. Between the fifth and eighth day of fever, a rash may spread to the arms and legs. This can vanish instantly or can become deeply coloured.
During the second week of fever, there are fair chances of the patient developing pneumonitis. In critical cases of scrub typhus, interstitial myocarditis is a more common symptom. Other severe signs include, increase in pulse rate, blood pressure drop, muscular spasms, stupor and disorientation.
Diagnosis of scrub typhus
The appearance of scabs on the skin calls for a diagnosis. Experts say that along with general tests, some specific tests must be carried out for efficient detection of the disease.
Diagnostic tests include:
- Indirect Immunofluorescence Antibody test
- ELISA (Enzyme-Linked Immunosorbent Assay) that detects and measures the antibodies in the blood
- Blood culture that checks for foreign intruders such as bacteria or other microorganisms
- Polymerase Chain Reaction (PCR)
- Weil-Felix, which is usually done for the diagnosis of rickettsial infections
Why there’s no vaccine
According to WHO, no effective vaccines are available for scrub typhus. Experts have discovered that there is a large antigenic variation in Orientia tsutsugamushi strains. To get an efficient level of protection, a scrub typhus vaccine must ideally give protection to all the strains present locally.
However, due to antigenic variation, a vaccine made for one locality may not work for another locality. This is a significant reason for the failure in developing a viable vaccine for scrub typhus.
For now, increasing awareness about the disease is key to avoiding it. Those travelling in the forest region or the endemic areas must wear protective clothing that covers arms and, especially, legs.
Reported casualties
In the recent months, one person died and more than 47 got infected with scrub typhus in Phullen village, about 125 km from Aizawl, capital of Mizoram. Other districts such as Lunglei, Champhai and Aizawl have also recorded some significant cases of scrub typhus. The disease is found in other parts of the country too.
The disease is endemic to parts of India, Korea, Japan, Northern Australia, and China. According to media reports, the virus of scrub typhus was found in Himachal Pradesh, Sikkim, and Darjeeling between 2003 and 2007. South India too has witnessed cases of the disease during winters.
This article was originally published on August 19, 2018.
This story has been contributed by Rajat Kalra, a member of 101Reporters.com, a pan-India network of grassroots reporters.
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