PE31.1-14 | Tuberculosis and Febrile Infections — Glossary

The standard NTEP regimen abbreviation: 2 months of Isoniazid (H) + Rifampicin (R) + Pyrazinamide (Z) + Ethambutol (E) in the intensive phase, followed by 4 months of H + R + E in the continuation phase; total 6 months; daily dosing throughout.

The WHO/NVBDCP recommended first-line treatment for uncomplicated Plasmodium falciparum malaria; combines an artemisinin derivative (artesunate) with a partner drug (sulfadoxine-pyrimethamine) to prevent resistance; a full 3-day course is essential.

An enzyme elevated in lymphocyte-rich exudates; CSF or pleural fluid ADA >10 U/L supports a diagnosis of TB pleural effusion or TBM when microbiological confirmation is lacking.

The molecular mechanism of diphtheria toxin's A fragment, which irreversibly inactivates elongation factor-2 (EF-2), halting protein synthesis and causing cell death in cardiac muscle, neural tissue, and other organs.

The primary vector for dengue and chikungunya; a day-biting mosquito that breeds in small collections of clean, stagnant water (flower pots, tyres, coolers); identifiable by distinctive black-and-white striped markings.

A broad-spectrum benzimidazole anthelmintic that inhibits tubulin polymerisation and glucose uptake in helminths; the drug of choice for soil-transmitted helminthiasis at 400 mg single dose (≥2 yr) or 200 mg (1–<2 yr). Also used at higher doses (15 mg/kg/day) for NCC.

A complication of invasive Entamoeba histolytica infection in which trophozoites travel via portal venules to liquefy right-lobe hepatic parenchyma, producing a cavity containing 'anchovy-sauce' pus (lysed hepatocytes), fever, and right hypochondrial pain.

The mechanism whereby pre-existing cross-reactive antibodies from a prior dengue infection with a different serotype enhance viral entry into macrophages in a secondary dengue infection, causing greater viraemia and more severe disease.

A sudden, severe drop in haemoglobin due to temporary arrest of red blood cell production in the bone marrow; occurs in patients with underlying haemolytic anaemias (sickle cell disease, hereditary spherocytosis) infected with parvovirus B19.

First-line treatment for uncomplicated P. falciparum malaria combining an artemisinin derivative (artemether, artesunate) with a partner drug (lumefantrine, amodiaquine) to prevent resistance; fastest parasite clearance of any antimalarial.

Alternating episodes of sympathetic (tachycardia, hypertension, sweating) and parasympathetic (bradycardia, hypotension) surges in severe tetanus, caused by tetanospasmin affecting the autonomic nervous system; a major cause of ICU mortality.

A macrolide antibiotic that achieves high intracellular concentrations in macrophages; the preferred oral agent for uncomplicated typhoid fever at 20 mg/kg/day for 7 days, effective against most MDR strains.

A liquid culture system (Mycobacterium Growth Indicator Tube) used to grow M. tuberculosis for definitive identification and full drug susceptibility testing; more rapid than solid LJ medium (1–3 weeks vs 4–8 weeks).

Live attenuated Mycobacterium bovis vaccine given intradermally at birth under the Indian NIS; provides ~80% protection against severe childhood TB forms (miliary TB and TBM) but limited protection against adult pulmonary TB; leaves a characteristic left-deltoid scar.

Bacille Calmette-Guérin, a live attenuated strain of Mycobacterium bovis given intradermally at birth in the Indian NIS; confers ~80% protection against severe childhood TB (miliary and TBM) but limited protection against adult pulmonary TB.

The most sensitive culture method for typhoid (>90%), remaining positive even after antibiotic treatment; invasive and reserved for cases with high clinical suspicion but repeatedly negative blood cultures.

Massive bilateral cervical lymphadenopathy combined with soft-tissue oedema in severe pharyngeal diphtheria, giving the neck a thick, bull-like appearance; a sign of severe local disease and high toxin load.

Cartridge-Based Nucleic Acid Amplification Test; the WHO/NTEP recommended rapid molecular test that detects M. tuberculosis DNA and rifampicin resistance (rpoB mutations) from clinical specimens in under 2 hours.

A third-generation cephalosporin given IV at 75–100 mg/kg/day; the drug of choice for severe or complicated typhoid fever, effective against MDR strains and used for 10–14 days.

The definitive diagnostic method for Enterobius vermicularis (pinworm), performed by applying transparent adhesive tape to the perianal skin on waking before bathing, then examining microscopically for the characteristic flat-sided oval ova.

The characteristic progression of the measles rash from the head and neck downward toward the trunk and limbs, reflecting secondary viraemia seed patterns.

A severe complication of P. falciparum malaria characterised by altered consciousness (Blantyre Coma Scale <2), seizures, and coma, caused by cytoadherence of infected RBCs to cerebral microvascular endothelium; treated with IV artesunate.

A vector-borne viral illness caused by chikungunya alphavirus (transmitted by Aedes aegypti/albopictus) characterised by sudden high fever and incapacitating symmetrical polyarthralgia that may persist for weeks to months after fever resolution.

A person who continues to excrete Salmonella Typhi in stool or urine for >1 year after acute typhoid fever, usually harbouring the organism in the gallbladder; an important reservoir for community spread.

A dumbbell-shaped abscess in TB cervical lymphadenitis where central caseation erodes through the deep fascia to produce a connected subcutaneous abscess, creating two compartments joined at the fascial defect.

TB diagnosed by microbiological confirmation (positive AFB smear, CBNAAT, or culture) from an appropriate clinical specimen; the highest diagnostic certainty category in the NTEP framework.

A constellation of fetal abnormalities — sensorineural hearing loss, congenital heart defects (PDA, pulmonary artery stenosis), cataracts, and microcephaly — resulting from rubella infection in the first trimester of pregnancy.

The last 4 months of TB treatment using three drugs (H, R, E); targets the persister organisms — slowly metabolising intracellular bacilli — to sterilise the lesion and prevent relapse after treatment completion.

The third phase of pertussis, lasting weeks to months, during which cough paroxysms gradually diminish in frequency and severity; the organism has been cleared but bronchial hyperreactivity persists.

The period of defervescence in dengue (typically days 3–7 of illness) when vascular permeability is maximal and plasma leaks into third spaces, causing haemoconcentration, pleural effusion, ascites, and risk of dengue shock.

The adhesion of P. falciparum-infected red blood cells to capillary endothelium via PfEMP1 protein; causes microvascular obstruction and contributes to cerebral malaria, placental malaria, and severe organ dysfunction.

A severe form of dengue characterised by plasma leakage sufficient to cause shock: pulse pressure <20 mmHg or hypotension with cold extremities, restlessness, and haemoconcentration; managed with urgent IV isotonic fluid resuscitation.

WHO 2009 criteria identifying dengue patients at risk of severe disease: abdominal pain/tenderness, persistent vomiting, clinical fluid accumulation (ascites/pleural effusion), mucosal bleeding, lethargy/restlessness, liver enlargement >2 cm, rising haematocrit with rapid platelet fall.

Seven clinical features indicating plasma leakage and the critical phase of dengue: abdominal pain/tenderness, persistent vomiting (≥3 episodes), clinical fluid accumulation, mucosal bleeding, lethargy/restlessness, liver enlargement >2 cm, rapid haematocrit rise with rapid platelet fall; any one requires hospitalisation.

A luminal amoebiocide active against intraluminal Entamoeba histolytica cysts; dosed at 20 mg/kg/day in 3 divided doses for 10 days as the follow-on agent after metronidazole.

Equine-derived antitoxin that neutralises circulating free diphtheria toxin; must be given immediately on clinical diagnosis without waiting for culture results; administered after horse-serum sensitivity testing.

A supervision strategy in which a designated health worker, ASHA worker, or community volunteer physically watches the patient swallow every dose of anti-TB medication; the cornerstone of NTEP adherence strategy and the most effective single intervention to prevent MDR-TB.

TB caused by M. tuberculosis resistant to one or more first-line drugs; MDR-TB is resistance to at least isoniazid and rifampicin; detected by CBNAAT (rifampicin resistance), LPA, or DST; managed by specialised NTEP DR-TB centres.

An immunodiffusion test performed on a culture plate to confirm toxigenicity of Corynebacterium diphtheriae; a precipitation line between the bacterial growth and an antitoxin-impregnated strip confirms toxin production.

Cytokines (IL-1β, IL-6, TNF-α, IFN-γ) released by monocytes and macrophages in response to infection or inflammation; they stimulate hypothalamic COX-2 to produce PGE2, which raises the thermal set-point.

A systemic illness caused by Salmonella typhi or S. paratyphi; characterised by step-ladder fever, relative bradycardia, rose spots, leucopenia, and hepatosplenomegaly; diagnosed by blood culture (gold standard); treated with IV ceftriaxone or oral azithromycin.

Peripheral blood eosinophil count >500 cells/µL or >5%; in the context of parasitic infections, it is characteristic of invasive helminthic infection (tissue-migrating larvae) and is NOT caused by intestinal protozoa.

A pattern of lobar or segmental collapse in childhood primary TB caused by hypersensitivity-mediated mucosal swelling or bronchial compression by lymph nodes; the collapse is disproportionate to the small primary focus.

The fifth childhood exanthem, caused by parvovirus B19, characterised by intense bilateral erythema of the cheeks ('slapped-cheek' appearance) followed by a lacy reticular rash on the limbs.

An Entamoeba histolytica trophozoite actively ingesting host red blood cells, seen in fresh warm stool — pathognomonic for invasive amoebiasis and a mandated trigger for dual-agent treatment.

A painless, black, necrotic skin lesion at the site of mite (chigger) bite in scrub typhus, representing focal skin necrosis caused by Orientia tsutsugamushi inoculation; pathognomonic when present but absent in 30–50% of cases.

A skin eruption (rash) occurring as a symptom of a systemic febrile illness, particularly those caused by viruses or bacteria.

A single tablet containing a predetermined ratio of multiple anti-TB drugs (H, R, Z, E in the intensive phase; H, R, E in the continuation phase); simplifies dosing, ensures correct drug ratios, and reduces the risk of selective drug discontinuation.

An elevation of body temperature above the normal range, conventionally defined as axillary temperature >37.4°C or rectal temperature >38°C in children; results from a reset of the hypothalamic thermal set-point by endogenous pyrogens.

Fever exceeding 38.3°C documented on at least 3 separate occasions, lasting >14 days, and remaining without a diagnosis after 1 week of thorough inpatient investigation; causes include infection, autoimmune disease, and malignancy.

An X-linked hereditary deficiency of the G6PD enzyme in red blood cells, reducing their ability to withstand oxidative stress; affected individuals suffer haemolytic crises when exposed to primaquine, dapsone, nitrofurantoin, or certain foods; G6PD testing is mandatory before prescribing primaquine.

An X-linked recessive enzyme deficiency (glucose-6-phosphate dehydrogenase) that renders red blood cells susceptible to oxidative haemolysis; primaquine causes life-threatening haemolytic anaemia in severely G6PD-deficient individuals; G6PD testing is mandatory before primaquine prescription.

A specimen collected by nasogastric tube early in the morning before feeding from the stomach of a fasting child; it contains swallowed respiratory secretions that harbour M. tuberculosis, making it the standard microbiological sample in non-expectorating children under 10 years.

A small (1–2 cm) area of caseous pneumonitis in the lung parenchyma, typically in the subpleural mid-zone, representing the initial site of M. tuberculosis implantation in primary infection.

A flagellate protozoan that colonises the upper small intestine causing malabsorption syndrome; presents as chronic foul-smelling greasy stools, bloating, and failure to thrive without blood, mucus, or fever; diagnosed by stool antigen ELISA or microscopy for pear-shaped trophozoites.

An acute angular kyphosis of the spine resulting from anterior collapse of one or more vertebral bodies in Pott's disease (TB spondylitis); a visible and palpable sharp posterior prominence.

Spread of M. tuberculosis via the bloodstream from the primary focus to distant organs (lungs → miliary nodules, meninges → TBM, vertebrae → Pott's, liver/spleen); most common in children <5 years with immature CMI.

A viral illness most commonly caused by coxsackievirus A16, producing fever, painful oral ulcers, and vesicles on the palms, soles, and buttocks.

Enlargement of the hilar or mediastinal lymph nodes visible on chest X-ray as widened or lobulated hilar shadows; the hallmark radiological sign of primary TB complex in children, often without or with a subtle parenchymal focus.

Soil-transmitted nematodes (Ancylostoma duodenale and Necator americanus) whose infective larvae penetrate bare skin, migrate to the intestine, and cause chronic intestinal blood loss and iron malabsorption, leading to iron-deficiency anaemia.

Dormant liver-stage forms of P. vivax and P. ovale that persist after the acute blood-stage infection resolves and can reactivate weeks to months later, causing relapse; eliminated by primaquine (requires G6PD testing first).

An in-vitro blood test (QuantiFERON-TB Gold, T-SPOT.TB) that detects IFN-γ release by sensitised T-cells in response to TB-specific antigens (ESAT-6, CFP-10); not affected by BCG vaccination, making it more specific than TST in vaccinated populations.

The profound immunosuppression lasting 2–3 years after measles infection, caused by the measles virus destroying memory B and T cells, rendering the child more susceptible to other infectious diseases.

Sputum collected after nebulisation with 3% hypertonic saline (with pre-treatment salbutamol) in children ≥5 years unable to spontaneously expectorate; sensitivity is comparable to gastric aspirate in older children.

The firm, palpable, raised area of skin at the Mantoux test site, reflecting delayed-type hypersensitivity; only induration is measured — erythema (redness) is NOT included.

The first 2 months of TB treatment using four drugs (H, R, Z, E); targets the rapidly multiplying extracellular bacillary population and reduces the bacterial load quickly; responsible for initial clinical improvement and smear/culture conversion.

The most feared complication of typhoid, occurring in the third week of illness as necrotic Peyer's patches slough through the full thickness of the ileal wall, causing peritonitis and pneumoperitoneum — a surgical emergency.

Administration of isoniazid 10 mg/kg/day (maximum 300 mg/day) for 6 months to a child with latent TB infection (positive TST, no active disease) or a child <5 years with household TB contact, to prevent progression to active disease.

Administration of isoniazid (INH) for 6 months to a child with LTBI (positive TST, no active disease) who is a household contact of a TB case, to prevent progression to active TB; recommended by NTEP/IAP.

Pathognomonic whitish, grain-of-salt-like lesions on the buccal mucosa opposite the lower molars, appearing 1–2 days before the measles rash and disappearing as the rash peaks.

A state of immunological sensitisation to M. tuberculosis (positive TST/IGRA) without clinical or radiological evidence of active disease; the organism remains dormant within macrophage granulomas.

Intracellular amastigote forms of Leishmania donovani found within macrophages in bone marrow, spleen, or liver on Giemsa-stained preparations; their presence confirms the diagnosis of visceral leishmaniasis.

A reduction in total white blood cell count (WBC <4,000/µL); characteristic of typhoid fever (WBC often 2,000–6,000/µL), in contrast to pyogenic bacterial infections which typically cause leucocytosis.

The NVBDCP first-line treatment for visceral leishmaniasis in India; administered intravenously (10 mg/kg single infusion or short-course schedule), with high efficacy and lower nephrotoxicity than conventional amphotericin B.

A selective culture medium used to grow Corynebacterium diphtheriae; the bacteria produce characteristic metachromatic granules (Babes-Ernst granules) visible on staining of colonies grown on this medium.

Transient pulmonary eosinophilia caused by larval migration of Ascaris (or other helminths) through the alveoli, producing cough, low-grade fever, fleeting bilateral infiltrates on chest X-ray, and peripheral eosinophilia; resolves spontaneously as larvae depart the lungs.

An insecticide-impregnated bed net used for malaria prevention; provides a physical and chemical barrier against night-biting Anopheles mosquitoes; a key tool of India's NVBDCP malaria elimination programme.

A rapid molecular test that detects mutations conferring resistance to first-line (isoniazid, rifampicin) and second-line (fluoroquinolones, injectable agents) anti-TB drugs in culture or direct specimen; used to characterise drug resistance after rifampicin resistance detected on CBNAAT.

A state of TB sensitisation (positive TST/IGRA) without clinical or radiological evidence of active disease; the bacilli are dormant within granulomas; treated with IPT to prevent progression to active TB.

A drug active against Entamoeba histolytica cysts in the intestinal lumen, used after tissue amoebiocide therapy to eliminate the cyst reservoir and prevent relapse; includes diloxanide furoate and paromomycin.

Infection by the filarial nematode Wuchereria bancrofti, transmitted by Culex mosquitoes; causes acute filarial fever and lymphangitis, and chronic lymphoedema progressing to elephantiasis of the limbs and genitalia.

An absolute increase in lymphocyte count in the peripheral blood; in pertussis, often strikingly elevated (>15,000/µL) due to pertussis toxin blocking lymphocyte egress from lymph nodes.

Specialised antigen-sampling epithelial cells overlying Peyer's patches in the small intestinal mucosa; Salmonella Typhi selectively invades through M cells to access the underlying lymphoid tissue.

Tuberculin skin test using 0.1 mL of PPD (5 TU) injected intradermally on the volar forearm; the transverse diameter of induration (not erythema) is measured at 48–72 hours to detect TB sensitisation.

Tuberculosis caused by M. tuberculosis resistant to at least isoniazid AND rifampicin — the two most potent first-line anti-TB drugs; requires 18–24 months of toxic second-line therapy; caused primarily by incomplete or irregular first-line treatment.

Bilateral, uniformly distributed 1–2 mm nodular opacities throughout both lung fields on chest X-ray, pathognomonic of miliary TB resulting from haematogenous dissemination of M. tuberculosis.

A form of disseminated TB resulting from haematogenous spread of bacilli; named for the millet-seed appearance of 1–2 mm bilateral lung nodules on chest X-ray; most common in children <2 years.

An oral phospholipid analogue antileishmanial (2.5 mg/kg/day for 28 days; for children ≥2 yr and >12 kg); the first oral agent for kala-azar, available as an alternative to L-AmB under the NVBDCP elimination programme.

A combined live-attenuated vaccine against measles, mumps, and rubella; administered at 9–12 months (first dose) and 16–24 months (booster) in the Indian National Immunization Schedule.

Medical Research Council classification of TBM severity: Stage I (alert, no neurological deficit), Stage II (altered consciousness or focal deficit), Stage III (coma or severe deficit); predicts prognosis and guides management intensity.

Strains resistant to the three classic first-line antibiotics — ampicillin, chloramphenicol, and cotrimoxazole; treated with ceftriaxone (IV) or azithromycin (oral).

India's biannual (February and August) public health programme delivering a single dose of albendazole to all children and adolescents aged 1–19 years through schools and Anganwadi centres, targeting soil-transmitted helminths.

Tetanus in a neonate (WHO definition: day 3–28 of life) due to Clostridium tetani infection of the umbilical stump from contaminated cord cutting or dressing, occurring when the mother is non-immune.

Severe, potentially fatal chickenpox in a neonate born to a mother who develops varicella within 5 days before to 2 days after delivery, when maternal antibodies have not been transferred in time to protect the newborn.

Infection of the central nervous system by the larval stage (cysticercus) of Taenia solium, the most common cause of acquired epilepsy in India; results from ingestion of T. solium eggs (not the pork tapeworm stage).

A transport medium added immediately to gastric aspirate specimens to counteract gastric acidity, which is bactericidal to M. tuberculosis; neutralisation within 30 minutes is essential to preserve organism viability for culture.

India's web-based national TB notification and patient management system; all TB cases (public and private sector) are legally required to be registered and followed up on Nikshay; it also manages Nikshay Poshan Yojana nutritional support payments.

A direct benefit transfer programme under NTEP paying ₹500/month to all notified TB patients during treatment to support nutritional intake; recognises that malnutrition is both a cause and a consequence of TB and that nutritional rehabilitation improves treatment outcomes.

Non-structural protein 1 of dengue virus; detectable in blood from day 1 of fever up to day 5; the most useful dengue diagnostic test in the acute febrile phase; sensitivity ~80–90% in days 1–5.

Dengue non-structural protein 1 antigen; detectable in blood from day 1 of symptoms and typically falls after day 5; the preferred dengue diagnostic test in the first 5 days of illness by rapid card test or ELISA.

National Tuberculosis Elimination Programme (formerly RNTCP — Revised National TB Control Programme); India's government programme for TB diagnosis, treatment, and prevention; provides free diagnosis and daily fixed-dose combination treatment to all TB patients.

India's national programme for TB prevention, diagnosis, and treatment, formerly known as RNTCP (Revised National TB Control Programme); renamed in 2020 to reflect the goal of TB elimination by 2025; provides free daily FDC treatment and DOT to all patients.

India's national programme for prevention and control of vector-borne diseases including malaria, dengue, chikungunya, lymphatic filariasis, kala-azar, and Japanese encephalitis; sets the national drug policy for malaria treatment.

Collapse of a lung segment or lobe due to external compression of the bronchus by enlarged hilar/mediastinal lymph nodes in childhood TB, a characteristically paediatric complication not seen in adult primary TB.

A posture of severe hyperextension of the head, neck, and back caused by sustained contraction of paraspinal and neck muscles in tetanus, sometimes called the 'arching' posture.

The obligate intracellular gram-negative coccobacillus causing scrub typhus; transmitted via the bite of larval Leptotrombidium mites (chiggers); invades vascular endothelium causing perivasculitis; treated with doxycycline.

Child-specific formulation of the anti-TB FDC with lower drug concentrations designed for weight-band dosing in children; provided free by NTEP; available in four weight-band formulations.

A family of negative-sense single-stranded RNA viruses including measles virus, mumps virus, and respiratory syncytial virus (RSV), transmitted by respiratory droplets.

An aminoglycoside antibiotic with luminal amoebiocidal activity (25–35 mg/kg/day for 7 days); an alternative luminal agent to diloxanide furoate, particularly useful in pregnancy and paediatric practice.

A series of short, explosive cough efforts in rapid succession, characteristic of pertussis, occurring as a unitary episode followed by a whooping inspiratory effort or apnoea in young infants.

Linear petechiae or ecchymoses in skin folds (particularly the antecubital fossa and inguinal creases) in scarlet fever, caused by capillary fragility from streptococcal exotoxins.

Containing very few mycobacteria; childhood TB (except adolescent cavitary disease) is paucibacillary — children have low bacillary loads making them rarely infectious and difficult to confirm microbiologically.

A combined vaccine containing antigens against diphtheria, pertussis, tetanus (DPT), hepatitis B, and Haemophilus influenzae type b (Hib); given in India at 6, 10, and 14 weeks of age under the National Immunization Schedule.

A Giemsa-stained thick and thin blood film used to diagnose malaria; the thick smear detects low parasitaemia and the thin smear identifies species morphology; the gold standard for malaria diagnosis at the peripheral level.

The principal virulence factor of Bordetella pertussis; causes lymphocytosis by blocking lymphocyte recirculation, and impairs phagocyte function by inhibiting G-protein signalling.

Organised lymphoid aggregates in the submucosa of the terminal ileum, serving as the primary site of Salmonella Typhi invasion; their progressive hyperplasia, necrosis, and sloughing underlie typhoid's intestinal complications.

The principal mediator of fever; synthesised by COX-2 in the hypothalamic endothelium in response to endogenous pyrogens; binds EP3 receptors to raise the hypothalamic temperature set-point; inhibited by paracetamol and NSAIDs.

The most common malaria species in India; causes tertian (every 48-hour) fever; establishes hypnozoites in the liver enabling relapse; treated with chloroquine (blood stage) + primaquine 14 days (radical cure of liver stage) after G6PD testing.

A rash comprising lesions at multiple stages of development simultaneously (macules, papules, vesicles, and crusts coexisting), characteristic of chickenpox and distinguishing it from smallpox.

Enlargement of lymph nodes behind the ear, characteristic of rubella, helping to differentiate it from measles (which causes generalised lymphadenopathy) and other viral exanthems.

Tuberculous spondylitis affecting the vertebral bodies (most commonly lower thoracic/thoracolumbar junction); anterior vertebral destruction causes wedge collapse, gibbus deformity, and risk of Pott's paraplegia from spinal cord compression.

A standardised preparation of M. tuberculosis proteins used in the Mantoux test; 5 tuberculin units (TU) in 0.1 mL is the standard dose for paediatric and adult testing in India.

A 8-aminoquinoline drug active against hepatic hypnozoites of P. vivax and P. ovale (radical cure — prevents relapse); also active against P. falciparum gametocytes (blocks transmission); contraindicated in G6PD deficiency due to risk of haemolytic anaemia.

The hallmark lesion of childhood TB: a parenchymal Ghon focus in the lung combined with ipsilateral hilar/mediastinal lymphadenopathy and connecting lymphangitis; represents the initial host response to primary M. tuberculosis infection.

TB diagnosed on the basis of clinical, epidemiological, immunological, and radiological evidence consistent with TB in the absence of microbiological confirmation; treated as TB in the NTEP/IAP framework.

A thick, grayish-white adherent membrane in diphtheria, composed of fibrin, necrotic cells, bacteria, and inflammatory debris, that bleeds when forcibly removed and can extend beyond the tonsillar pillars into the larynx.

A bactericidal anti-TB drug uniquely active against intracellular persister organisms in the acidic environment of macrophage phagosomes; included only in the intensive phase; its inclusion shortened the standard regimen from 9 to 6 months.

A point-of-care immunochromatographic test detecting Plasmodium antigens (HRP-2 for P. falciparum; pLDH for all species) from fingerprick blood; enables rapid diagnosis without microscopy in field settings.

A lateral flow immunochromatographic test detecting P. falciparum HRP-2 antigen or pan-Plasmodium pLDH; used at health facilities without microscopy; results in 15–20 minutes; positive RDT should ideally be confirmed with peripheral smear for species identification.

A paradoxically slow pulse rate relative to the degree of fever; classically seen in enteric fever (typhoid), where the pulse rate is lower than the 10 bpm/°C rise expected; it reflects the toxin-mediated effect on the conduction system.

Inhibitory interneurons in the ventral horn of the spinal cord that normally modulate motor neuron activity via glycine; their inhibition by tetanospasmin leads to the uncontrolled spasms of tetanus.

A rare, life-threatening condition characterised by hepatic failure and encephalopathy in children who receive aspirin during chickenpox or influenza, caused by mitochondrial dysfunction.

A rare but life-threatening condition of acute non-inflammatory encephalopathy and hepatic failure associated with aspirin use in children with viral illnesses (influenza, chickenpox, dengue); this risk absolutely contraindicates aspirin in children under 12 years.

Detected by CBNAAT as mutations in the rpoB gene; serves as a proxy for MDR-TB (multi-drug resistant TB); requires referral for Line Probe Assay and full drug susceptibility testing.

A fixed, sardonic grin caused by sustained spasm of the facial muscles (zygomaticus, risorius) in tetanus, one of the pathognomonic signs of generalised tetanus.

A recombinant kinesin antigen-based immunochromatographic rapid diagnostic test for visceral leishmaniasis, with >93% sensitivity and >97% specificity in India; endorsed by WHO as a field diagnostic, avoiding the need for bone marrow biopsy in endemic areas.

The predecessor programme to NTEP (1997–2020); used thrice-weekly intermittent dosing with older FDC formulations; superseded by NTEP in 2020 which introduced daily dosing and new diagnostic tools.

Faint, salmon-pink, blanching macular spots (2–4 mm) on the lower trunk and abdomen, representing dermal emboli of Salmonella Typhi bacteria in skin capillaries; present in 10–20% of typhoid cases.

A viral exanthem of infancy caused by HHV-6, characterised by 3–5 days of high spiking fever followed by the appearance of a maculopapular rash on the trunk as the fever resolves.

A biphasic fever pattern seen in some dengue cases: 2–3 days of high fever, a brief period of apparent improvement, then a second febrile period; less common than a single continuous fever but characteristic when present.

A systemic illness caused by Group A Streptococcus producing pyrogenic exotoxins (superantigens), characterised by pharyngitis, diffuse sandpaper erythematous rash, strawberry tongue, and Pastia lines.

The intense bilateral erythema of both cheeks with circumoral pallor characteristic of erythema infectiosum (parvovirus B19 infection), giving the child the appearance of having been slapped.

A group of intestinal parasitic worms (Ascaris, hookworm, Enterobius, Trichuris) transmitted through faecally contaminated soil; collectively among the most prevalent infections of childhood globally.

A bedside diagnostic test for tetanus: touching the posterior pharynx with a tongue depressor elicits reflex masseter contraction (biting) rather than gagging, due to hyperactive reflexes; reported high sensitivity in resource-limited settings.

A fever pattern in which daily temperature rises progressively without returning to baseline, creating a staircase-like pattern on the temperature chart; characteristic of typhoid in the first week of illness.

White-coated tongue with red papillae initially (white strawberry tongue, days 1–2) progressing to bright red papillae on a red background (red strawberry tongue, days 4–5) in scarlet fever.

A rare, progressive and universally fatal neurodegenerative disease caused by persistent defective measles virus in the brain, presenting 7–10 years after the original measles infection with cognitive decline and myoclonic jerks.

The neurotoxin produced by Clostridium tetani that cleaves synaptobrevin in inhibitory interneurons (Renshaw cells), blocking glycine and GABA release and causing unopposed motor neuron firing.

Human-derived immunoglobulin containing antibodies against tetanus toxin; given intramuscularly at diagnosis (3,000–10,000 IU) to neutralise unbound circulating tetanospasmin; preferred over equine antitoxin.

A drug that kills invasive Entamoeba histolytica trophozoites in the intestinal wall and liver; metronidazole and tinidazole are the principal agents. Not active against intraluminal cysts.

An NTEP outcome indicator: the proportion of TB patients who achieve 'cured' or 'treatment completed' outcomes; NTEP target is >90% for drug-sensitive TB; rates below this indicate programme deficiencies in adherence, drug supply, or contact management.

Inability to open the mouth due to spasm of the masseter (jaw-closing) muscles; the first clinical sign of tetanus and the basis for the common name 'lockjaw'.

Haematogenous seeding of the meninges by M. tuberculosis, causing a subacute lymphocytic meningitis with CSF low glucose and elevated protein; staged I–III by MRC criteria based on consciousness and neurological deficits.

A Vi polysaccharide vaccine conjugated to a carrier protein (Typbar-TCV); approved from ≥6 months of age, providing superior and longer-lasting immunity than the unconjugated Vi polysaccharide vaccine; included in India's NIS.

A severe form of typhoid encephalopathy characterised by profound confusion, muttering delirium, and altered consciousness from endotoxin-mediated brain dysfunction; associated with high mortality if untreated.

A cytological test performed by scraping the base of a vesicle and staining the material; positive (multinucleated giant cells) in herpes simplex virus and varicella-zoster virus infections, though not specific.

A herpesvirus causing primary chickenpox (varicella) and establishing lifelong latency in dorsal root ganglia, capable of reactivating as herpes zoster (shingles) in later life.

The capsular polysaccharide virulence antigen of Salmonella Typhi; inhibits complement activation and phagocytosis, aiding survival; the target antigen for the Vi polysaccharide typhoid vaccine.

A systemic protozoan infection caused by Leishmania donovani, transmitted by the sandfly Phlebotomus argentipes, characterised by prolonged fever, progressive splenomegaly, hepatomegaly, wasting, pancytopenia, and — if untreated — death.

WHO-recommended therapeutic intervention in measles to prevent complications including corneal ulceration and blindness; dosed by age (>12 months: 200,000 IU, 6–12 months: 100,000 IU, <6 months: 50,000 IU) on day 1 and day 2.

Water, Sanitation, and Hygiene — the foundational public health approach to typhoid prevention, encompassing safe drinking water (boiling, filtration), adequate sanitation (latrines), and handwashing with soap.

A serological test for scrub typhus detecting OXK antibody agglutination against Proteus mirabilis OXK; insensitive and non-specific — considered insufficient as sole diagnostic criterion; IgM ELISA or IFA for Orientia is the reference standard.

A serology test for enteric fever measuring agglutination titres against Salmonella typhi O (somatic) and H (flagellar) antigens; positive at O ≥1:160 and H ≥1:160, but has poor specificity due to cross-reactions; blood culture is the preferred diagnostic test.