(a) Describe the clinical features, diagnosis and treatment of Kala-azar. 20 marks (b) What are the types of vaccines currently…

(a) Kala-azar. Kala-azar is a systemic protozoal infection caused by Leishmania donovani, transmitted by the sandfly Phlebotomus argentipes. It presents after a variable incubation period with prolonged undulant or quotidian fever, often with chills, progressive weakness, weight loss and anorexia. The spleen enlarges massively and is usually larger than the liver; the spleen is firm and non-tender, while hepatomegaly may also be present. Lymphadenopathy is uncommon, and the spleen is usually the dominant feature. Pancytopenia causes anaemia, easy bruising and recurrent infections; hypergammaglobulinemia and hyperpigmentation are common, giving the disease its name. In advanced cases, oedema, cachexia and secondary infections may occur. India achieved the kala-azar elimination target (<1 case per 10,000 population in every endemic block) in 2023, but surveillance and case detection remain important in endemic districts such as Bihar, Jharkhand, Uttar Pradesh and West Bengal.

Diagnosis combines clinical suspicion with laboratory confirmation. Under the national programme, a positive rK39 rapid immunochromatographic test in a patient with fever for more than two weeks and splenomegaly, from an endemic area and without past kala-azar, is sufficient to start treatment. Because rK39 antibodies persist after cure, relapse and doubtful cases need parasitological confirmation. Parasitological demonstration of Leishman-Donovan bodies in splenic, bone-marrow or lymph-node aspirate is the standard. Culture and PCR can support the diagnosis. Treatment follows NVBDCP guidance: liposomal amphotericin B is preferred, commonly a single 10 mg/kg intravenous dose in the Indian subcontinent, with higher or repeated doses for relapse or severe disease. Miltefosine (oral, 28 days, with contraception) or combination therapy (such as miltefosine with paromomycin) may be used where indicated, and antimonials are avoided because of toxicity and resistance. Treatment is curative and reduces transmission; relapse is uncommon after L-AmB but follow-up is advised.

(b) Pneumococcal vaccines. The vaccines in use are pneumococcal conjugate vaccines (PCV) and pneumococcal polysaccharide vaccine. PCV13 is a 13-valent conjugate vaccine with the CRM197 carrier; PCV10 is available as Synflorix (protein D, tetanus and diphtheria toxoid carriers) and as India's indigenous Pneumosil (CRM197 carrier, Serum Institute), which is used in the UIP. Newer PCV15 and PCV20 are licensed for older age groups abroad. PPSV23 is a 23-valent polysaccharide vaccine, mainly for older children, adults and high-risk groups. PCV induces T-cell dependent immunity and is effective in infants; PPSV23 induces T-cell independent antibody responses and is not preferred for young infants. In the National Immunization Schedule, PCV was introduced in a phased manner from 2017 and is given at 6 weeks and 14 weeks of age with a booster at 9 months (2 + 1 schedule). It safeguards against invasive pneumococcal disease (bacteraemia/sepsis and meningitis), pneumonia, otitis media and sinusitis, and reduces carriage, giving a herd effect.

(c)(i) Hair-dye dermatitis. The diagnosis is acute allergic contact dermatitis due to paraphenylenediamine (PPD), a primary aromatic amine and primary intermediate in oxidative hair dye, not a coupler. PPD is a potent sensitizer; sensitization may occur after initial exposure, and subsequent reactions appear within 24-48 hours. The history of repeated dye use, with acute inflammatory papules and vesicles on the scalp and ear tips, is characteristic of an acute eczematous reaction at the sites of dye contact (scalp, hairline, ears, forehead and neck).

(c)(ii) Confirmation. Confirmation is by patch testing with PPD 1% pet, preferably as part of the Indian Standard Series, applied on the upper back and read at 48 and 72–96 hours, once the acute eruption has settled and systemic steroids are stopped. Histopathology (spongiosis with lymphocytic infiltrate) is only supportive; the temporal relation to repeated exposure supports the diagnosis.

(c)(iii) Treatment. Treatment begins with immediate cessation of the dye and avoidance of further contact. Oozing vesicular areas are treated with cool wet compresses (saline or potassium permanganate), and potent topical corticosteroids (such as betamethasone valerate lotion on the scalp) are applied, with systemic antihistamines for itching. In severe or widespread cases, a short course of oral corticosteroids may be given. The patient should be educated to avoid PPD-containing products and to use hypoallergenic alternatives, while beauticians should use gloves and patch-test clients, reducing occupational dermatitis burden.