What is enteric fever? What are its causative agents? Give a detailed presentation of a case according to the time of the disease and the respective tests used for diagnosis.

Draw a diagram of HIV virion depicting the various antigens and proteins.

Question

What is enteric fever? What are its causative agents? Give a detailed presentation of a case according to the time of the disease and the respective tests used for diagnosis.

Draw a diagram of HIV virion depicting the various antigens and proteins. Give the serological pattern in an HIV infection according to the time of presentation. List the various diseases associated with AIDS.

What is virtual autopsy? State its methodology. What are its merits?

Define brain death. Describe its medicolegal importance.

Discuss why infliximab is considered as an immunosuppressant. Mention its therapeutic uses.

Describe briefly the pharmacological characteristics of natriuretic peptides and their clinical uses.

UPSC Answer Check · Accepted Answer

(a)(i) Enteric fever. Enteric fever is an acute systemic infection common in India, caused by Salmonella Typhi and S. Paratyphi A, B, C. After 1–2 weeks incubation, week 1 shows fever, headache, malaise and relative bradycardia; blood culture is positive (the best early test; bone-marrow culture is the most sensitive, even after antibiotics). Typhoid state and leucopenia may be present. Week 2 shows step-ladder fever, rose spots on trunk, hepatosplenomegaly; stool culture becomes positive. Week 3 may show intestinal haemorrhage or perforation; Widal test shows rising O and H titres, and urine culture may be positive. Week 4 is defervescence and recovery. (a)(ii) HIV. Virion diagram: [envelope: gp120 surface spikes, gp41 transmembrane] → [matrix: p17] → [capsid: conical p24] → [core: two ssRNA, reverse transcriptase, integrase, protease, RNase H]. ```svg ``` Serologically, HIV RNA appears at 10–14 days; p24 antigen at 15–20 days; antibody by ELISA at 3–12 weeks (window period), shortened to about 2–4 weeks by 4th-generation p24/antibody assays; in India, NACO confirms infection by a three-test strategy using assays based on different antigens or principles (Western blot is now rarely used); CD4 count falls progressively. AIDS is diagnosed when CD4 <200 cells/µL or an AIDS-defining illness appears. Diseases include TB, PCP, cryptococcal meningitis, Kaposi sarcoma, CMV retinitis, toxoplasmosis, MAC, candidiasis, histoplasmosis, non-Hodgkin lymphoma, HIV encephalopathy, wasting and invasive cervical cancer. (b)(i) Virtual autopsy. Virtual autopsy (virtopsy) is a non-invasive or minimally invasive post-mortem examination using post-mortem CT (PMCT), PMCT angiography, post-mortem MRI, 3D surface scanning and image-guided needle biopsy, with 3D reconstruction and virtual dissection. In India, AIIMS New Delhi started it with ICMR support. Methodology includes imaging, radiological interpretation, comparison with antemortem records and, where needed, targeted correlation. It documents internal injuries without opening the body. Merits: preserves the body, is rapid in mass disasters, useful in trauma and religious objections, though histopathology is limited. (b)(ii) Brain death. Brain death is irreversible loss of all brain and brainstem function. After excluding reversible causes (drugs, hypothermia, metabolic disturbance), it is shown by deep coma, absent brainstem reflexes and a positive apnoea test, repeated after an interval; EEG or angiography may confirm it. Medicolegally, under the Transplantation of Human Organs Act, 1994, in India, as amended in 2011, formal certification by a Board of four medical experts is mandatory for legal death, consent and organ retrieval. It must be distinguished from coma and the persistent vegetative state, in which brainstem function persists. It permits withdrawal of life support, issuance of a legal death certificate and organ retrieval. (c)(i) Infliximab. Infliximab is a chimeric anti-TNF-α monoclonal antibody; it neutralises soluble and membrane-bound TNF-α, suppressing macrophage/T-cell activation and granulomatous inflammation, hence immunosuppressant. It is used in moderate-severe Crohn’s disease, ulcerative colitis, rheumatoid arthritis, ankylosing spondylitis and psoriasis; risks include TB reactivation (screen before use), serious infections, infusion reactions, anti-drug antibodies, worsening heart failure, demyelination and hepatosplenic T-cell lymphoma. (c)(ii) Natriuretic peptides. ANP is atrial, BNP ventricular and CNP endothelial; they activate GC-A/GC-B receptors, raise cGMP, causing vasodilation, natriuresis and diuresis and inhibiting the RAAS. They are degraded by neprilysin, and neprilysin inhibition with sacubitril (combined with valsartan) is now a key heart-failure therapy. Clinically, BNP >400 pg/mL or NT-proBNP >450 (<50 y), >900 (50–75 y) or >1800 (>75 y) pg/mL rules in acute heart failure; they guide prognosis and nesiritide is used in acute decompensated heart failure.

What is enteric fever? What are its causative agents? Give a detailed presentation of a case according to the time of the disease…

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