Acute Respiratory
Infection
• Acute respiratory infections
(ARIs) are classified as upper
respiratory tract infections
(URIs) or lower respiratory
tract infections (LRIs)
• The upper respiratory tract
consists of the airways from
the nostrils to the vocal cords
in the larynx, including the
paranasal sinuses and the
middle ear. The lower
respiratory tract covers the
continuation of the airways
from the trachea and bronchi
to the bronchioles and the
alveoli.
Signs and Symptoms
• The early symptoms of acute respiratory infection usually
appear in the nose and upper lungs. These symptoms
include:
• congestion, either in the nasal sinuses or lungs
• runny nose
• cough
• sore throat
• body aches
• fatigue
• If the disease advances, there may be high fever and chills.
Other serious symptoms are:
• difficulty breathing
• dizziness
• low blood oxygen level
• loss of consciousness
Cause and Mode of Transmission
• The vast majority of URIs have a viral etiology. Rhinoviruses
account for 25-30% of URIs; respiratory syncytial viruses (RSVs),
parainfluenza and influenza viruses, human metapneumovirus, and
adenoviruses for 25-35%; corona viruses for 10%; and unidentified
viruses for the remainder.
• The common LRIs are pneumonia and bronchitis. Currently, the
most common causes of viral LRIs are RSVs. They tend to be highly
seasonal, unlike parainfluenza viruses, the next most common
cause of viral LRIs.
• Bacteria are the most common cause of community-acquired
pneumonia, with Streptococcus pneumoniae isolated in nearly 50%
of cases.
• Viruses have two modes of transmission: via aerosols of respiratory
droplets and from fomites (contaminated surfaces), including direct
person-to-person contact.
• Most bacteria enter the lungs via small aspirations of organisms
residing in the throat or nose.
Lab Tests and Diagnostic Tests
• Diagnosis is typically based on a person's signs and symptoms. The
color of the sputum does not indicate if the infection is viral or
bacterial.
• Symptoms of URTIs commonly include cough, sore throat, runny
nose, nasal congestion, headache, low grade fever, facial pressure
and sneezing.
• WHO clinical guidelines for ARI case management (WHO 1991) use
two key clinical signs: respiratory rate, to distinguish children with
pneumonia from those without, and lower chest wall indrawing, to
identify severe pneumonia requiring referral and hospital admission.
• The World Health Organization (WHO) respiratory rate thresholds
for identifying children affected with pneumonia are as follows:
• Children younger than 2 months: ≥ 60 breaths/min
• Children aged 2-11 months: ≥ 50 breaths/min
• Children aged 12-59 months: ≥ 40 breaths/min
• The Philippine Practice Guidelines Group in Infectious Diseases
(PPGG-ID) defines the respiratory rate threshold for adults as ≥ 30
breaths/min
Algorithm for the Management-
Oriented Risk Stratification of
Community-Acquired Pneumonia
(CAP) in Immunocompetent
Adults
Source: PPD’s Compendium of Philippine Medicine, 10th Edition (2008)
Lab Tests and Diagnostic Tests
• Children with audible stridor when calm and at rest
or such danger signs of severe disease as inability to
feed also require referral. Children without these
signs are classified as having an ARI but not
pneumonia.
• Acute bronchitis: The most common symptom is
a cough. Other symptoms include coughing up
mucus, wheezing, shortness of breath, fever, and
chest discomfort.
Nonpharmacologic and
Pharmacologic Therapy
• Interventions to control ARIs can be divided into four
basic categories: immunization against specific
pathogens, early diagnosis and treatment of disease,
improvements in nutrition, and safer environments.
• URTIs: Treatment comprises symptomatic support
usually via analgesics for headache, sore throat and
muscle aches. Health authorities have been strongly
encouraging physicians to decrease the prescribing of
antibiotics to treat common URTIs because antibiotic
usage does not significantly reduce recovery time for
these viral illnesses.
Nonpharmacologic and
Pharmacologic Therapy
• LRTIs: Oral antibiotics (for bacterial pneumonia), rest,
simple analgesics, and fluids usually suffice for
complete resolution.
• In previously healthy adult patients judged to have
low risk CAP, S. pneumoniae and H. influenzae are the
predominant etiologic agents in more than half of
cases where a pathogen is identified. Amoxicillin is
considered to be the standard regimen for these
patients' outpatient care. In areas with limited
resources, cotrimoxazole is a practical cost-effective
alternative.
• Acute bronchitis often does not require antibiotic
therapy and use of cough medicine.
Empiric Antimicrobial Therapy
in CAP
Source: PPD’s Compendium of Philippine Medicine, 10th Ed. (2008)
Nonpharmacologic and
Pharmacologic Therapy
• Prevention is by not smoking and avoiding other
lung irritants.
• Frequent hand washing may also be protective.
• Widespread use of vaccines against measles,
diphtheria, pertussis, Hib, pneumococcus, and
influenza has the potential to substantially reduce
the incidence of ARIs in children in developing
countries.
References
• PPD’s Compendium of Philippine Medicine, 10th Ed.
(2008)
• http://www.ncbi.nlm.nih.gov/books/NBK11786/
• http://www.healthline.com/health/acute-
respiratory-disease#Causes2
• http://emedicine.medscape.com/article/967822-
overview
