Question
A 40 year old male presented with complaints of unexplained fever, loss of weight, persistent diarrhoea and generalized lymphadenopathy for past six months. He gave a history of exposure with multiple sex partners
- (a) What is the most probable diagnosis 1 mark(s)
- (b) Describe the modes of transmission of this disease 2 mark(s)
- (c) Describe the laboratory diagnosis in detail 4 mark(s)
- (d) Name two acid fast parasites causing diarrhoea in this condition e) Describe the post exposure prophylaxis of this disease 1 mark(s)
Answer
a) Most probable diagnosis: AIDS (HIV infection) — unexplained fever, weight loss, persistent diarrhoea, and generalized lymphadenopathy for six months in a patient with a history of multiple sexual exposures is classical of advanced HIV disease.
b) Modes of transmission: sexual contact (the predominant route, relevant to this patient’s exposure history); parenteral (blood/blood products, contaminated needles/injecting drug use, needle-stick injury); vertical/perinatal (mother-to-child — in utero, during delivery, or via breastfeeding).
c) Laboratory diagnosis
- Screening: ELISA for HIV antibody — 4th-generation combination assays detect both p24 antigen and antibody, narrowing the window period.
- Rapid tests: point-of-care immunochromatographic rapid antibody tests.
- Confirmatory test: Western blot or NACO Strategy III (three different tests/kits based on different principles, tested serially, all reactive required for confirmation).
- CD4 count: flow cytometry, for staging and prophylaxis decisions.
- Viral load: quantitative HIV RNA PCR, for monitoring treatment response.
d) Two acid-fast parasites causing diarrhoea in this condition: Cryptosporidium parvum and Isospora (Cystoisospora) belli — both demonstrated by modified Ziehl-Neelsen (modified acid-fast) staining of stool.
e) Post-exposure prophylaxis Combination antiretroviral therapy (ART) started as soon as possible (ideally within 72 hours) after a high-risk exposure (e.g., needle-stick injury, unprotected sexual exposure to a known/suspected HIV-positive source), continued for 28 days, alongside baseline and follow-up HIV testing of the exposed individual.