Metapneumovirus infections overlaps with respiratory syncytial viral infections in a number of ways:
(1) age of patients infected (most are infants and young children)
(2) time of year (winter)
(3) signs and symptoms
Clinical findings used in the illness score:
(1) cough
(2) rhinitis
(3) fever (body temperature >= 38°C)
(4) dyspnea
(5) wheezing
(6) feeding difficulties (decreased food intake, other)
(7) chest retractions while breathing
(8) hyperventilation (> 60 breaths per minute if <= 1 year of age; > 40 breaths per minute if > 1 year of age)
(9) tachycardia (pulse > 175 per minute if 0-3 months old; > 177 if 3-6 months old; > 163 if 6-12 months old; > 143 if > 12 months old)
(10) cyanosis
(11) hypoxemia (oxygen saturation < 95%)
(12) hypercapnia (PaCO2 > 5.6 kPa or 42 mm Hg)
(13) decreased hemoglobin (< 8.1 mmol/L if <= 1 month; < 6.6 mmol/L if > 1 month)
(14) decreased hematocrit (< 42% if <= 1 month; < 33% if > 1 month)
(15) thrombocytosis (> 390,000 per µL or 390 * 10^9/L if <= 1 month of age; > 473,000 per µL or 473 * 10^9/L if > 1 month of age)
where:
• Scoring both decreased hemoglobin and decreased hematocrit seems redundant.
• The conversion factor for hemoglobin appears to be 0.621 for going from g/dL to mmol/L (page 151, Young DS, Huth EJ. SI Units for Clinical Measurement).
|
Clinical Finding
|
Points
|
|
absent
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0
|
|
present
|
1
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illness score =
= SUM(number of findings present) / SUM(number of findings recorded)
Interpretation:
• minimum illness score: 0
• maximum illness score: 1
• RSV was associated with higher illness scores, with mean 0.50 (range 0.44 to 0.56)
• Metapneumovirus had a mean illness score of 0.38 (range 0.33 to 0.44).
