Scrub Typhus - A potentially life threatening fever ?

 What is scrub typhus ?

    Orientia tsutsugamushi, an obligate intracellular gram-negative bacterium, is the source of the acute febrile illness known as scrub typhus. Although scrub typhus caused by other Orientia species has been reported in Africa, France, the Middle East, and South America, it is believed to be endemic to the tsutsugamushi triangle, which includes Asia, northern Australia, and islands in the Indian and Pacific Oceans. According to a recent systematic review from hospital-based studies in India, scrub typhus was the root cause of 25% of acute undifferentiated febrile illnesses. 

     O. tsutsugamushi transmitted by the bites of infected chiggars( trombiculid mite) has been linked in recent studies to acute encephalitis syndrome (AES) outbreaks in India, particularly in the northern states of Uttar Pradesh, Bihar, West Bengal, and Assam. Outbreaks of AES pose a major public health problem in India, predominantly affecting children. 

Spectrum of Clinical Features-

      All patients who exhibit an acute onset of fever and altered mental status are included in the broad definition of Acute Encephalitis Syndrome used for syndromic surveillance. Typical clinical features include fever with chills & rigor ,headache,bodyaches,muscle cramps,altered sensorium ,lymphadenopathy and rash .

 The pathognomonic classical scrub typhus rash has been described as a dark scab like region at the site of the chiggar bite, popularly known as 'Eschar'.

      The clinical manifestation may be brought on by encephalitis, meningitis, or encephalopathy without CNS invasion, such as in cases of severe systemic infection, metabolic disturbance, or other neurologic complications following the infection. 

Diagnostic Challenges-

        Early diagnosis is essential for starting prompt, targeted treatment, which can lower scrub typhus complications and fatality rates. Due to the symptoms' similarity to those of other tropical infections that are endemic to the region and can also cause AES, such as dengue, chikungunya, malaria, and leptospirosis, clinical diagnosis can be difficult. 

       There are drawbacks to the current microbiological diagnostics for scrub typhus, which are typically based on IgM detection in serum samples or nucleic acid by PCR. IgM can persist for a long time after the onset of acute illness, and it can react with IgM from other cocirculating pathogens. IgM first appears in serum 5–6 days after the onset of illness .Therefore, it is challenging to determine O. tsutsugamushi as the cause in AES patients who also have microbiological evidence of another potential pathogen.

        Patients with suspected neurologic scrub typhus do not undergo routine IgM detection in cerebrospinal fluid (CSF).The immunofluorescence assay has long been regarded as the gold standard in serologic testing, but its use is constrained by its high cost and difficult interpretation. Serologic tests' limitations in terms of cross-reacting and persistent antibodies may be addressed by PCR, but a positive result is only likely to occur during the bacteremia stage of infection .

        Additionally, blood or eschar material are suggested samples for O. tsutsugamushi PCR, whereas it is unknown how sensitive PCR is to CSF.

          More than 50% of patients had anaemia, leukocytosis, thrombocytopenia, transaminitis, hypoalbuminemia, and uremia. Most patients' CSF tests showed lymphocytic pleocytosis and increased protein concentration.

Treatment-

       Doxycycline 100mg twice daily x 10 days has been the drug of choice for most of the patients without having obvious comorbid conditions. Supportive therapy in terms of Paracetamol, Intravenous Fluids etc are often required. Comorbid conditions like Diabetes Mellitus, Pre-existing Nephropathy can lead to AKI like manifestations in selected group of patients. Hence a constant vigilant monitoring of serum creatinine, electrolytes along with CRP/Procalcitonin  may be of importance to optimise the therapeutic outcome. 

Typhoid vaccine price in India - Know why it is worth the cost

 What is Typhoid Fever ?

    A potentially fatal multisystemic infection known as enteric fever, also known as typhoid fever is caused primarily by Salmonella enterica serotype typhi and, to a lesser extent, paratyphi A, B, and C. ICD 10 code for enteric fever is now A01.00. Salmonella are motile enterobacteriaceae that can cause a number of different gastrointestinal infections. Typhoid, which is primarily caused by Salmonella enterica serotype typhi and, to a lesser extent, S enterica serotypes paratyphi A, B, and C, is the most dangerous of these. From a severe septic illness to minor cases of diarrhoea with low-grade fever, it can present in a wide range of ways. Fever, malaise, diffuse abdominal pain, and constipation are characteristics of the classic presentation. Typhoid fever that is left untreated can lead to delirium, obtundation, intestinal bleeding, bowel perforation, and death in less than a month.

    It has grown more and more resistant to antibiotics over time. Extensively drug-resistant typhoid (XDR) was reported in Pakistan in 2016. Azithromycin, carbapenems, and tigecycline are the only antimicrobial classes that are still effective against these strains.

     Conditions of poor sanitation, overcrowding, and social unrest favour the growth of typhoid.  Typhoid fever is still endemic in developing nations, despite the fact that antibiotics have significantly decreased its prevalence in the developed world. It's possible that S paratyphi infections are becoming more common than S typhi infections. This might be brought on by the immunologic immaturity of a particular population as well as the insufficient protection against these pathogens offered by the current Typhoid vaccines. Most commonly, non-Typhoidal strains cause a mild, self-limiting gastroenteritis. Nevertheless Typhoid vaccines play a crucial role both in primary prevention and decreasing the disease severity in affected individuals.

Vaccines for prevention :

Courtesy : Dr Koushik's Medicare 

        Typhoid fever can be prevented by two vaccinations. The first is a live, attenuated (weakened) vaccine, and the second is an inactivated (dead) vaccine. Which typhoid vaccine is ideal for you can be decided with the aid of your doctor. Typhoid vaccination that has been inactivated is given by injection. Children of 2 years of age and older may receive it. At least two weeks prior to departure, one dose is advised. For those who continue to be at danger, repeated doses every two years are advised.

        Oral live typhoid vaccine administration (by mouth). Six years of age and older individuals may receive it. Every other day, one capsule is taken, making a total of four capsules. At least a week before departure, the last dose should be taken.About an hour before meals, each capsule should be taken whole (without chewing) with cold or lukewarm water. For those who continue to be at risk, a booster shot is required every five years. It's crucial to keep live typhoid vaccine capsules chilled (not frozen).

      In developed countries  most of the time routine typhoid immunisation is not advised, although the following situations may warrant administration of typhoid vaccines.

a) Tourists going to regions where typhoid is widespread. (NOTE: Typhoid vaccination is not 100% effective and is not a replacement for exercising caution while choosing foods and beverages.)

b) Individuals in close proximity to a typhoid carrier.

c) Employees in laboratories that handle Salmonella typhi bacterial culture and strains

The typhoid vaccine may be administered concurrently with other shots.

     In 2023 typhoid vaccine price in India is around INR 1500-2500 based on the brands available. You can check the same on : https://www.apollopharmacy.in/medicine/typbar-tcv-pfs-injection-0-5ml

     Typbar TCV Vaccine 0.5 ml. It includes sodium chloride and the purified Vi polysaccharide typhoid vaccine. Typhoid disease is prevented with it. A non-toxic and safe form of the causative bacteria's capsular specimen is injected into the body by Typbar TCV Vaccine, which prompts the body to produce antibodies and confers immunity. The body keeps track of this immune response to ensure that it is ready in the event that these bacteria invade again in the future.