A fever cluster in a village of 4,200 people in late August
You are the community health nurse at a primary health centre serving a village of 4,200 people. In the last 10 days the ASHA has reported 27 people with fever, of whom 6 have had a platelet count below 100,000/µL and 2 have been confirmed NS1 positive for dengue at a private laboratory. Most cases are clustered in two adjoining lanes and the onset dates form a rising curve over the past week. It has rained heavily for a fortnight, and the team finds stagnant water in discarded tyres, plastic containers and overhead tanks; 14 of 40 houses inspected have at least one container with Aedes larvae, and 22 positive containers were counted. Two patients with high fever are taking ibuprofen bought from a shop. The district has not been informed. The medical officer is on leave for two days.
1. Is this an outbreak? What steps would you take in the first 48 hours and what data would you collect?
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Assessment The pattern is suggestive: a rise in cases above the expected number for the area and season, a tight geographical cluster in two lanes, a rising epidemic curve, and confirmed NS1 positivity with thrombocytopenia. A cluster becomes an outbreak when cases exceed the expected number for that place and time; the working decision should be to treat it as a suspected dengue outbreak and let surveillance data confirm or refute it. The nurse should not wait for the medical officer to return.
First 48 hours
- Inform the district surveillance unit under the Integrated Disease Surveillance Programme by phone and in writing the same day; dengue is a notifiable condition. Delay in notification is itself a lapse.
- Active house-to-house case search in the affected lanes and surrounding areas to find fever cases not presenting to the health centre.
- Prepare a line list: name, age, sex, address, date of onset, fever duration, warning signs, platelet count, NS1 or IgM result, hospitalisation and outcome.
- Draw an epidemic curve by date of onset and a spot map marking cases and larval breeding sites, to identify a common source or continuing transmission.
- Ensure every household with a fever case knows the warning signs and where to go, and that all fever cases are reviewed daily.
- Stop the sale and use of NSAIDs in the village through the ASHA and shopkeepers - ibuprofen and aspirin increase bleeding risk in dengue.
- Start vector control at once, since mosquito control cannot wait for laboratory confirmation.
2. Using the larval survey numbers, plan the vector control response and state which interventions are justified and which are not.
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Interpreting the numbers
- House (premises) index = 14 ÷ 40 × 100 = 35%. A house index above 5% indicates high risk of transmission; this is seven times that.
- Breteau index = 22 positive containers per 40 houses × 100 = 55. Values above 20 indicate high risk. Both indices confirm intense breeding, so source reduction is the main intervention - adulticiding alone will not control this.
Justified interventions
- Source reduction: a weekly dry day in every household, emptying and scrubbing containers, overhead tanks, desert cooler trays, tyres and plastic waste; covering water storage; filling or removing discarded containers.
- Temephos 1 ppm in containers that cannot be emptied or covered, applied by trained staff, with the dose explained to households.
- Larvivorous fish in large permanent water bodies and tanks where appropriate.
- Fogging with pyrethrum or malathion only during an outbreak, for adult mosquito control, at the correct dose and time, alongside - never instead of - source reduction.
- Personal protection: repellents, full-sleeved clothing, bed nets for day-sleeping infants, and screening of windows.
- Health education through the ASHA, school teachers and village health and sanitation committee, with the message that Aedes breeds in clean water and bites during the day.
Not justified
- Fogging as a stand-alone or routine monthly measure; it gives brief relief, breeds resistance and creates a false sense of security.
- Spraying indoors for Aedes, which rests outdoors and in cool shaded places.
- Insecticide treatment of drinking water with unsafe chemicals.
3. Which patients must be referred, and what is the ASHA's and the nurse's role in preventing deaths?
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Refer immediately to the community health centre or district hospital
- Any warning sign: persistent vomiting, abdominal pain or tenderness, bleeding gums or nose, black stools or vomiting blood, lethargy or restlessness, cold clammy skin, urine output falling, breathlessness, a rapid fall in platelet count with a rising haematocrit.
- Severe dengue: shock, significant bleeding, fluid overload, or organ involvement.
- Infants, pregnant women, the elderly, and people with diabetes, hypertension or other comorbidity - refer early even with mild illness, as they deteriorate faster.
- Any patient with fever who cannot be reviewed daily.
ASHA's role
- Active surveillance and daily follow-up of every fever case in her catchment for the first five days.
- Recognising and reporting warning signs the same day, using the referral slip and arranging 108 transport; accompanying the patient where possible.
- Counselling on oral fluids, paracetamol only, and never aspirin, ibuprofen or combination cold remedies.
- Ensuring the household removes breeding sites and knows the next review date.
The nurse's role
- Confirm the line list is complete, follow up pending platelet counts, and check that referred patients actually reached the facility.
- Do not give platelet transfusions prophylactically - they are not indicated without active bleeding.
- Complete the district surveillance returns weekly, monitor the epidemic curve for a fall, and continue vector control for at least two weeks after the last case.
- Document everything, including the times of notification, because dengue deaths are frequently reviewed for delay in referral.