Question
A 14 years old boy presents with complaints of fever, headache, retro bulbar pain maculopapular rash, pain in the back and limbs for the past ten days. The fever is typically biphasic in nature. Answer the following. What is the probable diagnosis and the causative agent How the disease is transmitted. Name two other diseases transmitted in the same way. Name the investigations for specific diagnosis and test for complications Name two complications of this disease What are the preventing measures to be employed (1+2+2+3+2)
Answer
Probable diagnosis and causative agent: Dengue fever — biphasic fever, retro-orbital pain, maculopapular rash, and severe bone/joint/muscle pain (“breakbone fever”) over ten days is classical. Causative agent: Dengue virus (a Flavivirus, four serotypes DENV-1 to DENV-4).
Transmission: transmitted by the bite of the Aedes aegypti mosquito (a day-biting mosquito; Aedes albopictus is a secondary vector). Two other diseases transmitted the same way (by Aedes mosquitoes): Chikungunya and Zika virus infection (yellow fever is also a valid example, transmitted by the same vector genus).
Investigations for specific diagnosis and complications:
- NS1 antigen — detectable from day 1, before antibody develops.
- IgM ELISA — positive from about day 5, indicating recent infection.
- RT-PCR — detects viral RNA in the early viraemic phase, allows serotyping.
- Full blood count — thrombocytopenia and rising haematocrit (haemoconcentration) are key tests for detecting complications (plasma leakage, DHF/DSS).
- Liver function tests — for hepatic involvement.
Two complications: Dengue Haemorrhagic Fever (DHF) — thrombocytopenia and plasma leakage; Dengue Shock Syndrome (DSS) — severe plasma leakage causing circulatory failure/shock.
Preventive measures: mosquito control (source reduction — eliminating stagnant water breeding sites, larvicides, insecticide spraying); personal protective measures (repellents, protective clothing, bed nets/screens, especially in daytime); community health education; dengue vaccination where available for select endemic populations.