Dengue
Which cells are primarily targeted during cross-reactive viral uptake in secondary Dengue, causing severe plasma leak?
Monocytes and Macrophages
What pathognomonic necrotic skin lesion resembling a cigarette burn is diagnostic for Scrub Typhus? Name causative organism?
An eschar is a painless, classic skin ulcer with a dark, necrotic scab ("cigarette-burn" appearance) that develops at the site of a larval Trombiculid mite (chigger) bite.
What classic, painless ocular physical finding is highly suggestive of Leptospirosis during its early clinical phase?
Conjunctival suffusion
A patient with high enteric fever presents with relativebradycardia, where the heart rate does not increase proportionally withbody temperature. What is this classic clinical sign called?
Fagets sign
To prevent relapses in patients diagnosed with Plasmodium vivax or Plasmodium ovale malaria, therapy must target which dormant liver stage of the parasite?
Hypnozoites
A livestock handler presents with an undulant fever,drenching night sweats, and localized lower back pain found to besacroiliitis. History reveals consumption of unpasteurized goat cheese.What is the most likely pathogen?
Brucella species
A patient presents with acute fever and severe, debilitating polyarthralgia that makes walking difficult. While often confused with Dengue, this vector-borne infection rarely causes life-threatening shock or severe thrombocytopenia. What is the most likely diagnosis?
Chikungunya Fever
What is the standard first-line therapeutic agent and its adult dosage for treating uncomplicated Scrub Typhus, and what is the preferred primary alternative during pregnancy?
The first-line therapeutic agent is Doxycycline (100 mg orally or intravenously twice daily for 7 to 10 days). During pregnancy, Azithromycin (500 mg orally once daily for 5 days) is the preferred primary alternative, as tetracyclines are avoided due to fetal bone and dental deposition risks.
Which clinical phase of Leptospirosis, also known as Weil's Disease, is associated with high mortality?
Anicteric Phase
Leptospiremic Phase
Icteric Phase (Correct)
Convalescent Phase
What is the pharmacokinetic rationale for using Azithromycin as a first-line oral agent for managing uncomplicated, fluoroquinolone-resistant enteric fever?
Azithromycin achieves exceptionally high intracellular concentrations within macrophages, monocytes, and mucosal Peyer's patches (up to 50 times higher than serum levels).
What is the definitive initial antimalarial regimen for a child presenting with severe Plasmodium falciparum malaria, and what is the protocol for transitioning to oral intake?
Immediate initiation of intravenous Artesunate (2.4mg/kg ) IV administered at 0, 12, and 24\hours, and then once daily). Once the patient can tolerate oral intake and their parasite density has dropped, they must complete a full 3-day course of an oral Artemisinin-based Combination Therapy (ACT) to clear the remaining parasite burden.
What is the preferred, first-line antimicrobial combination and duration for managing uncomplicated Brucellosis without focal osteoarticular or neurological involvement?
The standard regimen is oral Doxycycline (100 mg PO twice daily) combined with oral Rifampicin (600–900 mg PO once daily). Both drugs must be taken continuously for a minimum duration of 6 weeks.
Rumpel-Leede test
Simple, rapid bedside test is used to evaluate capillary fragility in patients presenting with a suspected Dengue infection, and is considered positive if ≥10 to 20 petechiae per square inch develop
Which specific outer membrane protein gene serves as the primary molecular target for diagnostic real-time Polymerase Chain Reaction (qPCR) assays used to identify Orientia tsutsugamushi?
The primary target is the gene encoding the 56-kDa type-specific antigen (TSA), which is a major outer membrane protein unique to Orientia tsutsugamushi.
What is the definitive reference standard serological test for confirming a diagnosis of Leptospirosis?
MAT
Which diagnostic diagnostic specimen retains thehighest sensitivity (80-90%) for identifying Salmonella Typhi, evenafter the initiation of empiric antimicrobial therapy?
Bone marrow aspirate culture
Why can an antigen-based Rapid Diagnostic Test (RDT) targeting Plasmodium falciparum Histidine-Rich Protein 2 (PfHRP2) remain positive for weeks following a complete parasitological cure?
PfHRP2 is heavily secreted by active trophozoites and possesses a prolonged circulatory half-life, persisting in the bloodstream for 2 to 4 weeks after the parasites have been cleared by antimalarial therapy.
What specific safety and protocol instructions must be communicated to the microbiology laboratory when processing blood cultures from a patient with suspected systemic Brucellosis?
The clinician must explicitly flag the sample for suspected Brucella so the lab can institute Biosafety Level 3 (BSL-3) containment protocols to prevent laboratory-acquired infection via aerosol transmission. Additionally, the lab should be instructed to extend the incubation period of the culture bottles for up to 21 to 28 days
A 6-year-old female with severe Dengue has successfully passed through the defervescence window (Day 8 of illness). Her hematocrit has stabilized at 35%, and plasma leakage markers have resolved. However, she develops a persistent, unremitting spikes of high-grade fever (>39.5 ∘ C), worsening hepatosplenomegaly, progressive pancytopenia (WBC 1,200/μL, Hb 7.8 g/dL, Platelets 9,000/μL), extreme hyperferritinemia (14,500 ng/mL), fasting triglycerides of 410 mg/dL, and a fibrinogen level of 95 mg/dL. Repeated blood cultures are sterile. What secondary, immune-mediated complication has most likely been triggered by this viral infection?
Dengue-induced secondary Hemophagocytic Lymphohistiocytosis (sHLH) / Macrophage Activation Syndrome (MAS).
Describe the specific cellular target and the underlying cellular pathogenetic mechanism that leads to non-cardiogenic pulmonary edema (ARDS) in severe rickettsial infections.
VE-cadherin and claudin-5
Explain the molecular mechanism by which pathogenic Leptospira induces severe, non-oliguric hypokalemic acute kidney injury (AKI).
Outer membrane proteins of pathogenic Leptospira bind to and downregulate the sodium-potassium-chloride cotransporter 2 (NKCC2) in the thick ascending limb of Henle's loop, while simultaneously impairing epithelial sodium channels (ENaC) in the cortical collecting duct. This leads to an acute tubulointerstitial nephritis
What are the key immunological differences and target-population advantages of the WHO-prequalified Typhoid Conjugate Vaccine (TCV) compared to the older Vi capsular polysaccharide vaccine?
The older Vi polysaccharide vaccine is a T-cell independent antigen, which does not induce immunological memory, exhibits rapidly waning immunity, and is ineffective in children under 2 years old. TCV covalently links the Vi polysaccharide to a tetanus toxoid carrier protein, converting it into a T-cell dependent antigen. This alteration activates helper T-cells, induces robust immunological memory, provides long-lasting immunity, and allows effective administration to infants as young as 6 months of age.
What specific molecular genetic marker confirms the presence of artemisinin resistance in Plasmodium falciparum, and what is the phenotypic presentation of this resistance in the ICU?
Artemisinin resistance is confirmed by specific non-synonymous mutations in the propeller domain of the Kelch 13 (K13) gene on parasite chromosome 13. Phenotypically, it presents as a delayed parasite clearance half-life (taking 5-6 hrs to reduce parasitemia by half) or persistent parasitemia on Day 3 of treatment, despite direct adherence to IV Artesunate.
What classic neuroimaging abnormalities on a brain MRI point directly to a diagnosis of JE?
The hallmark MRI signature is bilateral, symmetrical T2-weighted and FLAIR hyperintensities located within the thalami.
Sulodexide ?
Heparanase Inhibitors & Glycocalyx Stabilizers (Protecting the Surface Layer), acts as a direct inhibitor of activated heparanase, preventing it from degrading heparan sulfate fragments in the extracellular matrix.
It provides results within an hour via visual inspection of turbidity or fluorescence. This gives it high clinical utility as a point-of-care test in resource-limited endemic zones, allowing for definitive molecular diagnosis days before serological IgM titers rise. Name the test?
Loop-Mediated Isothermal Amplification (LAMP) assay
What is the membrane lipoprotein unique to pathogenic Leptospira interrogans that serves as the benchmark target for advanced subunit vaccine development.
The benchmark target is LipL32, the most abundant outer membrane lipoprotein exclusive to pathogenic Leptospira strains.
Explain the genomic mechanisms and plasmid profiles responsible for the emergence of Extensively Drug-Resistant (XDR) Salmonella Typhi strains in South Asia.
XDR S. Typhi evolved when an endemic multi-drug resistant (MDR) strain of the H58 haplotype acquired an IncHI1 plasmid carrying resistance genes against chloramphenicol, ampicillin, and co-trimoxazole, and subsequently integrated a chromosomal transposon encoding the CTX-M-15 extended-spectrum beta-lactamase (ESBL) gene.
How should you manage the anti-relapse (radical cure) phase in a patient recovering from severe Plasmodium vivax malaria who is found to have a quantitative G6PD enzyme activity level below 30% of the institutional mean?
Daily Primaquine (0.5 mg/kg for 14 days) or single-dose Tafenoquine is strictly contraindicated due to the high risk of life-threatening acute intravascular hemolysis. Instead, after stabilizing the acute illness with IV Artesunate, administer Primaquine at an altered dose of 45 mg orally once a week for exactly 8 consecutive weeks. This weekly schedule must be conducted under close clinical and hematological monitoring, with a low threshold to transfuse if hemolysis occurs.
What are the cornerstones of acute management in the ICU and long-term prevention for JE?
Supportive, National Immunization Schedule using the live attenuated SA 14-14-2 vaccine (given at 9 months and 16–24 months) or tissue-culture-derived inactivated vaccines.