What you should know about Scrub Typhus & Dengue this season

The monsoon season is upon us, and is common knowledge, a host of diseases will be on the rise. The temperature fluctuation, the stagnation of water, spike in humidity, all lead to an environment which promotes the growth of insects, bacteria, fungi, and all types of micro-organisms.

It is commonly known in India that diseases like Malaria, Typhoid, Common Cold, Dengue, Cholera, Hepatitis A, Diarrhoea, Fungal infections, Respiratory tract infections, Leptospirosis and Viral infections are on the rise.

Dengue especially rears its ugly head this time of the year. Dengue virus is transmitted by female mosquitoes mainly of the species Aedes aegypti and, to a lesser extent, Ae. albopictus. This mosquito also transmits chikungunya, yellow fever and Zika infection.  Widespread infections are caused by increase in rainfall, tropical/sub-tropical temperatures, and unplanned urbanization. This makes India the perfect place for Dengue outbreaks.

Dengue
Synptoms & Occurence of Dengue

The Aedes aegypti mosquito lives in urban habitats and breeds mostly in man-made containers. The transmitting mosquito is a day-time feeder; its peak biting periods are early in the morning and in the evening before dusk. The female can bite multiple people during each feeding period.

Symptoms of dengue present itself as high fever, rash, muscle & joint pain.

The disease has also been termed “breakbone fever” because the unusually severe muscle and joint pains can make people assume distorted body positions or exaggerated walking movements in an effort to reduce their pain.

However, one disease that is overlooked during this season is Scrub Typhus.

Scrubb Typhus
Regions of Asia where Scrub Typhus occurs

Scrub Typhus is a disease endemic to South Asia, among other neighbouring regions, and presents similar symptoms as dengue – high fever, rashes, severe headache, chills etc.

Since Scrub Typhus has symptoms that can be easily mistaken for other diseases, it becomes important to know about the occurrence and symptoms. The non-specific presentation and lack of the characteristic eschar in 40% patients makes the misdiagnosis and under-reporting of scrub typhus common.

Scrub typhus is transmitted to humans and rodents by a species of mites (or “chiggers”). The mite is very small (0.2 – 0.4mm) and can only be seen through a microscope or magnifying glass. The disease is transmitted to humans from the bites of the infected mites. This bites leaves a characteristic black eschar, or lesion, in the area of the bite. This is useful to doctors for helping in correct diagnosis of the disease.

Scrub chigger
The Scrub Typhus mite

Symptoms may include muscle and gastrointestinal pains. More virulent strains of O. tsutsugamushi can cause haemorrhaging and intravascular coagulation. Complications may include atypical pneumonia, overwhelming pneumonia with adult respiratory distress syndrome

 

Scrub typhus is generally seen in people whose occupational or recreational activities bring them into contact with environments favourable to hosting mites, or rodents that host these mites.

When compared specifically with dengue, the following similarities and differences occur:

  1. Scrub typhus & Dengue both present with high fever, rashes and body aches
  2. However, Dengue presents with bleeding while Scrub typhus will have the characteristic black eschar or lesions at point of bites
  3. Clinically, Dengue and Scrub typhus will both cause reduced platelet count
  4. Differentiating factors are that Dengue will cause low White Blood Cell count where as Scrub Typhus will cause an increase, if at all, of White Blood Cells.
  5. Both will present itself during the monsoons in India.
  6. Dengue is cause by mosquito bites while Scrub Typhus is caused by bites of mites or ticks
Scrub Typhus mite bite
Typical Eschar or lesion from Scrub Typhus

Diagnosis of both can be based on blood samples. Dengue can be detected by running an ns1 antigen and IgM/IgG antibody tests, while scrub typhus can be detected by IgM antibody tests. For clear differentiation, viral detection PCR tests can be run for both.

The treatment of both also differs – Dengue is treated symptomatically with ample rest and increase in fluid intake.

Scrub Typhus is to be treated with antibiotics. The drug most commonly used is doxycycline; but chloramphenicol is an alternative. Azithromycin or chloramphenicol is useful for treating infection in children or pregnant women.

To summarize, it is necessary we understand the difference in the two diseases and their symptoms, so as to avoid a misdiagnosis, and early care for faster recovery.

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