Acute respiratory infection

    Last updated date: 02-Jun-2023

    Originally Written in English

    Acute Respiratory Infection

    Acute Respiratory Infection

    Upper respiratory infections and lower respiratory infections are the two kinds of acute respiratory infections. The airways from the nose to the vocal cords in the larynx, as well as the paranasal sinuses and the middle ear, make up the upper respiratory system. The extension of the airways from the trachea and bronchi to the bronchioles and alveoli is represented by the lower respiratory tract. Because of the possibility of infection or microbial toxins spreading throughout the body, inflammation, and impaired lung function, acute respiratory infections have systemic consequences. Diphtheria, pertussis (whooping cough), and measles are vaccine-preventable infections that attack the respiratory system as well as other organs.

    Except during the newborn period, acute respiratory infections are the most prevalent cause of sickness and death in children under the age of five, with an average of three to seven episodes per year, independent of where they reside or their financial position. However, the percentage of mild to severe disease differs between high- and low-income nations, and the severity of lower respiratory tract infections in children under five is worse in developing countries due to differences in specific etiologies and risk factors, resulting in a higher case-fatality rate. Despite the fact that medical treatment can reduce both severity and fatality to some amount, many severe lower respiratory tract infections do not benefit from treatment, owing to a lack of very potent antiviral medications. Every year, 11 million children die. According to statistics, 2 million people died from acute respiratory infections in 2000, with 70 percent of them dying in Africa and Southeast Asia. According to the World Health Organization, 2 million children under the age of five die of pneumonia each year.


    Upper Respiratory Tract Infections

    The most frequent infectious illnesses are upper respiratory tract infections. They include common cold, sinusitis, ear infections, acute pharyngitis or tonsillopharyngitis, epiglottitis, and laryngitis—the last two causing the most serious sequelae (deafness and acute rheumatic fever, respectively). A large percentage of upper respiratory tract infections are caused by viruses. Rhinoviruses cause 25 to 30 percent of URIs, followed by respiratory syncytial viruses (RSVs), parainfluenza and influenza viruses, human metapneumovirus, and adenoviruses, which account for 25 to 35 percent of upper respiratory tract infections, coronaviruses for 10%, and unknown viruses for the rest. The complications of upper respiratory tract infections are more significant than the infections because most upper respiratory tract infections are self-limiting. Acute viral infections predispose infants to bacterial infections of the sinuses and middle ear, and lower respiratory tract infections can be caused by inhalation of infected discharges and cells.


    Acute Rhinitis (Common Cold)

    Acute Rhinitis (Common Cold)

    Acute rhinitis, generally known as the common cold, is an acute, self-limited viral illness of the upper respiratory tract that can also affect the lower respiratory tract. All patients are familiar with the symptom complex that includes rhinorrhea, nasal congestion, and a raw or itchy throat.

    Colds are the most prevalent cause of human disease and are the leading cause of school and job absences. Children are particularly vulnerable since they have not yet developed protection to many viral infections, have poor personal hygiene, and have regular close contact with other children who are expelling viruses.

    Because some causal viruses do not create durable protection after infection and some viruses have multiple serotypes, colds are widespread.


    Symptoms of Common Cold

    The symptoms of the common cold are unaffected by the virus that causes it. Rhinorrhea, nasal blockage, and a sore or itchy throat are common in older children and adults. Patients can cough or sneeze, and the rhinorrhea is initially clear but may turn colored as the disease progresses.


    Treatment of Common Cold

    There are currently no effective antiviral medicines for the treatment of the common cold. There is little strong evidence to prove the use of symptomatic therapies in children, despite the fact that a variety of drugs can be used to alleviate symptoms. Because the common cold is a self-limited disease with primarily subjective symptoms, a considerable placebo effect can suggest that different therapies are effective. Insufficient placebo blinding can make an ineffective treatment appear effective in the research.

    Antibiotics have no place in the treatment of a child's uncomplicated common cold. Antibiotic treatment does not speed up the resolution of a viral illness or minimize the risk of secondary bacterial infection.


    Laryngotracheobronchitis (Croup) 


    Croup is characterized by laryngotracheitis, laryngotracheobronchitis, and laryngotracheobronchopneumonitis. Croup is a frequent tracheal, laryngeal, and bronchial infection that causes inspiratory stridor and a barking cough. Croup is usually caused by the parainfluenza virus, but it can also be caused by a bacterial infection. Croup is first and foremost a clinical diagnostic. Epiglottitis or a foreign body in the airway, both of which can be life-threatening, must be excluded first. All children with croup should be given corticosteroids, with epinephrine reserved for those with moderate to severe croup. children should also receive oxygen to ensure adequate oxygenation.  

    Croup is most usually caused by a virus, but it can also be caused by bacteria.


    Viral Causes of Coup

    1. Types 1 and 2 of the parainfluenza viruses are the most frequent cause of viral croup or acute laryngotracheitis.
    2. Influenza A and B, measles, adenovirus, and respiratory syncytial virus are among the other causes.
    3. Viruses that cause spasmodic croup also induce acute laryngotracheitis, but there are no indications of infection.


    Bacterial Causes of Croup

    1. Diphtheria, bacterial tracheitis, and laryngotracheobronchitis are the four types of bacterial croup.
    2. Corynebacterium diphtheriae typically causes laryngeal diphtheria. Bacterial tracheitis and laryngotracheobronchitis are all viral diseases that deteriorate as bacterial events take over.
    3. Staphylococcus aureus, Streptococcus pneumoniae, Hemophilus influenzae, and Moraxella catarrhalis are the most prevalent bacterial culprits.

    Infiltration of white blood cells produces enlargement of the larynx, trachea, and big bronchi in croup. Swelling causes partial airway blockage, which results in a dramatically increased effort of breathing and the distinctive turbulent, noisy airflow known as stridor when it is severe.


    Treatment of Croup

    The severity of the croup is determined by the Westley croup score. A single dosage of dexamethasone is administered to children with mild croup, defined as a Westley croup score of less than two. In addition to dexamethasone, children with moderate to severe croup, characterized as a Westley croup score of 3 or above, are given nebulized epinephrine. Supplemental oxygen should be given to patients with low oxygen saturation. Moderate to serious conditions need up to 4 hours of monitoring, after which admission is recommended if the symptoms do not improve. Croup is primarily a viral infection. When a main or secondary bacterial infection is suspected, antibiotics are used.




    Epiglottitis is an inflammatory disorder affecting the epiglottis and associated tissues such as the arytenoids, aryepiglottic grooves, and vallecula that is usually caused by bacterial infection. Epiglottitis is a life-threatening illness in which the upper airways expand dramatically, resulting in suffocation and respiratory arrest.

    The majority of cases were caused by H.influenzae bacteria before the advent of the Hemophilus influenzae type b vaccine, and the disease was significantly more frequent. Pathogens responsible in the post-vaccine era are more diverse and can also be polymicrobial. As a result, the term supraglottitis is frequently used to describe infections that affect the supraglottic tissues in general. Swelling of the epiglottis and supraglottic structures can proceed slowly until a critical mass is established, at which point the clinical situation can quickly deteriorate, leading to airway blockage, respiratory failure, and death. Patient distress and agitation can worsen symptoms, especially in children. So, doctors should pay attention to calm the patient.


    Causes of Epiglottitis

    Epiglottitis is most usually caused by an infectious agent, such as a bacterial, viral, or fungal infection. Hemophilus influenzae type B is still the most frequent cause of infection in youngsters. However, since the increased availability of vaccines, this has decreased considerably. Other bacteria have been involved, including Streptococcus pyogenes, Streptococcus pneumoniae, and Streptococcus aureus. Pseudomonas aeruginosa and Candida have been identified as pathogens in immunocompromised individuals. Traumatic factors, such as heat, caustic, or foreign body ingestion, are noninfectious causes of epiglottitis.


    Symptoms of Epiglottitis

    Symptoms may be moderate for hours or even days before rapidly worsening, giving the appearance of a sudden beginning. This normally happens within the last day, but it might also happen within the last 12 hours. The patient will appear to be in a lot of pain and may be toxic. Prodromal signs are absent in the majority of youngsters. The youngster will most likely be sitting straight with his mouth open in a tripod position in the emergency room, with a muffled voice. Adults may be suppressing their symptoms, but they are unlikely to lie flat or feel uncomfortable while doing so. There may be drooling, dysphagia, distress, or anxiety.


    Treatment of Epiglottitis

    Securing the airway is the single most crucial part of treatment. Because these individuals' airways are considered problematic, experienced clinicians should intubate them. If a tracheotomy is required, someone who can do it should be available. Inhalation induction of general anesthesia and subsequent intubation are most likely involved; however, this varies from patient to patient. After the airway has been secured, the patient should be admitted to the intensive care unit, and culture samples should be sent at the time of intubation. The use of corticosteroids to minimize swelling has been linked to a reduction in the length of time these patients spend in critical care. Antimicrobials should be started on an empiric basis. The regimen should be changed once the culture and sensitivity data are obtained. Extubation (removing the endotracheal tube) can be considered once a leakage around the endotracheal tube can be shown with the cuff deflated.




    The palatine tonsils, also known as faucial tonsils, are located in the lateral oropharynx. The palatine arches or pillars are located between the palatoglossal arch anteriorly and the palatopharyngeal arch posteriorly. The tonsils, along with the adenoids (nasopharyngeal tonsil), tubal tonsil, and lingual tonsil, form Waldeyer's ring, which is made up of lymphoid tissue. They provide the earliest immunological shield to insults, making them vital protection against inhaled or ingested infections.

    Tonsillitis, or tonsil inflammation, is a frequent ailment that accounts for about 1.3 percent of office visits. It is usually caused by a viral or bacterial infection and manifests as a sore throat when uncomplicated. Acute tonsillitis is a medical condition. It can be difficult to distinguish between bacterial and viral causes, but it is necessary to avoid antibiotic abuse.


    Causes of Tonsilitis

    Tonsillitis is usually induced by a viral or bacterial infection. The most common causes are viral infections. The most prevalent viral culprits are rhinovirus, respiratory syncytial virus, adenovirus, and coronavirus, which all cause the common cold. These are usually low-virulent and cause few problems. Tonsillitis can also be caused by viruses such as Epstein-Barr virus (which causes mononucleosis), CMV, hepatitis A, rubella, and HIV.

    Group A beta-hemolytic Streptococcus is the most common cause of bacterial infections, however Staphylococcus aureus, Streptococcus pneumoniae, and Hemophilus influenza have all been cultivated. Both aerobic and anaerobic microorganisms can cause bacterial tonsillitis. Corynebacterium diphtheriae, which causes diphtheria, should be considered as a cause in unvaccinated individuals. HIV, syphilis, gonorrhea, and chlamydia are all causative agents in sexually active people. Recurrent tonsillitis has also been linked to tuberculosis; thus, clinicians should analyze their patients' risks.


    Symptoms of Tonsilitis

    Fever, tonsillar exudates, painful throat, and tender anterior cervical lymphadenopathy are all symptoms of acute tonsillitis. As a result of the tonsillar enlargement, patients may experience odynophagia and dysphagia.


    Treatment of Tonsilitis 

    Tonsillitis is a self-limiting condition for the vast majority of people. Because viral causes are so common, supportive care, such as analgesics and hydration, is the basis of treatment for acute tonsillitis; patients rarely end up in the hospital. NSAIDs, for example, can help with relieving symptoms. Corticosteroids, usually administered as a single dosage of dexamethasone, can be used as an adjunctive treatment to reduce pain and enhance recovery time. While research has shown that steroids cause little harm, they must be used with caution in people who have medical comorbidities such as diabetes. The efficacy of natural remedies and herbal cures has been uneven and restricted. Zinc gluconate is not a suggested treatment option.

    Antibiotics are frequently used in the treatment of patients who are at high danger of bacterial pharyngitis based on Centor criteria and antigen testing or throat culture. The most prevalent cause of bacterial tonsillitis is Streptococcus pyogenes, and if antibiotic therapy is necessary, penicillin is usually the drug of choice.


    Lower Respiratory Tract Infections

    Lower Respiratory Tract Infections

    Pneumonia and bronchiolitis are the most frequent lower respiratory tract illnesses in children. In children who are coughing and breathing fast, the respiratory rate is a useful clinical indicator for detecting acute lower respiratory tract infections. The presence of indrawing on the lower chest wall indicates a more serious condition.

    Respiratory syncytial viruses (RSVs) are presently the most prevalent viral lower respiratory tract illnesses. Unlike parainfluenza viruses, which are the second leading cause of viral lower respiratory tract infections, they are very seasonal. Because safe and efficient vaccines are accessible, the prevalence of influenza viruses in children in impoverished countries requires immediate attention. The measles virus was the most common viral cause of respiratory tract–related morbidity and premature mortality in children in underdeveloped countries before the successful use of the measles vaccine.




    Pneumonia is a bacterial infection of the lungs that usually affects the alveolar space. Colonization is the existence of bacteria in the alveolar space without an associated inflammatory process; it is not pneumonia. A variety of different infections can affect the lungs and can be categorized based on the primary source of infection.


    Causes of Pneumonia

    Pneumonia can be caused by viral, bacterial, or fungal agents. Influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 (COVID-19) are the most frequent causes of viral pneumonia in the United States. Streptococcus pneumonia, along with Hemophilus pneumonia and staphylococcus aureus, is a frequent cause of bacterial pneumonia. Physicians, on the other hand, are not always able to determine which bacteria caused someone to become ill with pneumonia.


    Symptoms of Pneumonia

    Patients with pneumonia typically have a mixture of respiratory symptoms, such as cough, breathlessness, sputum formation, and chest discomfort, as well as systemic symptoms such as fever, chills, myalgia, and disorientation. Confusion is more likely among the elderly and the terminally ill. Immunocompromised individuals, and to a lesser extent, elderly people, may not produce a robust immune reaction, resulting in more modest symptoms. About 10 percent of community-acquired pneumonia patients come to the hospital with only extrapulmonary symptoms, such as falls, widespread weakness, and acute stomach discomfort. In these conditions, a high level of suspicion is needed.


    Treatment of Pneumonia

    Initial risk classification of the patient is performed to determine if the patient should be managed as an outpatient, on a general medical ward, or in an intensive care unit. The "CURB-65" scale has been widely utilized in this regard. Confusion, uremia (BUN greater than 20 mg/dl), a respiratory rate 30 or greater per minute, blood pressure under 90 mm Hg systolic or under 60 mm Hg diastolic, and an age older than 65 are all factors on this scale. Every favorable criterion that the patient fulfills is worth one point.

    1. Outpatient management is indicated by a score of 0 to 1. If adverse comorbidities are present, these individuals are treated empirically with Fluoroquinolones or Beta-lactams with Macrolides, and if no comorbidities are present, they are treated with Macrolides or Doxycycline.
    2. Hospitalization and treatment in a general medical ward are indicated by a score of 2 to 3. A combination of fluoroquinolones or macrolides with beta-lactams is the first treatment option.
    3. A score of 4 or more necessitates intensive care unit management. In this scenario, the empiric treatment is a combination of beta-lactam and fluoroquinolones or beta-lactams and macrolides.

    The ATS guidelines for the treatment of hospital-acquired pneumonia are followed. When compared to the treatment of community-acquired pneumonia, it is significantly longer, more difficult, and requires the administration of broad-spectrum antibiotics.




    Bronchiolitis is a common lung disease in children and adolescents. The lower respiratory tract is infected with the virus, which can cause mild to moderate respiratory discomfort. The respiratory syncytial virus is the most common cause (RSV). Bronchiolitis is usually a minor, self-limiting infection in children, but it can occasionally lead to respiratory failure in babies. Bronchiolitis is treated with hydration and oxygen therapy. The infection is not treated with any special drugs.


    Causes of Bronchiolitis

    The respiratory syncytial virus is the most frequent virus linked to bronchiolitis. However, numerous additional viruses have been discovered to induce the same infection over the years, including the following:

    1. Rhinoviruses 
    2. Coronaviruses
    3. Metapneumovirus
    4. Adenovirus
    5. Parainfluenza virus.
    6. Bocavirus


    Symptoms of Bronchiolitis

    Symptoms of an upper respiratory tract infection, including cough, fever, and runny nose, occur once RSV is encountered. The acute infection affecting the lower airways will show up in two to three days. During the acute period, the baby may experience a small airway blockage, resulting in respiratory distress signs. Crackles, wheezing, and rhonchi will be discovered during the physical examination. Difficulty breathing might range in intensity from infant to infant. Some infants will just have rapid breathing, while others will have significant retractions, grunting, and cyanosis. The disease may continue for 7 to 10 days, during which time the infant may become fussy and refuse to eat. Most babies, however, improve within 14 to 21 days if they are sufficiently hydrated.


    Treatment of Bronchiolitis

    Symptomatic treatment is the cornerstone of bronchiolitis treatment for children. All infants and children with bronchiolitis should have their hydration levels checked, as well as their breathing difficulties and hypoxia degrees.

    Treatment options for children with mild to severe symptoms include nasal saline, antipyretics, and a cool-mist humidifier. Children with serious signs of acute respiratory distress, hypoxia, and/or dehydration should be hospitalized and closely monitored. These kids require a lot of hydrations. In children with bronchiolitis, beta-adrenergic agonists such as epinephrine or albuterol, as well as steroids, have not been demonstrated to be beneficial. Rather, humidified oxygen and nebulized hypertonic saline should be administered to these children. It's critical to keep the children hydrated, especially if they are unable to feed. It is sufficient to use oxygen therapy to keep oxygen saturation just above 90 percent.



    The research suggests that the WHO case-management strategy and increased use of available vaccinations will cut acute respiratory infections mortality in young kids by up to two-third. The systematic use of simple case management, which is inexpensive enough for practically any developing country to adopt, will decrease acute respiratory infections mortality by at least a third.

    Emerging difficulties of resistant bacteria, diminished effectiveness of conventional medications with the recommended antimicrobial drugs, or the advent of unexpected pathogenic organisms must be identified early and remedial steps are taken quickly, according to the case-management strategy, which must be implemented and experimentally evaluated. It will be better to apply and evaluate the IMCI strategy if community-level action by healthcare personnel is reinforced by the adoption of the strategy at all levels of primary care. This kind of collaboration could also aid in obtaining data that can be used to fine-tune clinical indicators so that even village healthcare practitioners can tell the difference between bronchiolitis and wheezing and bacterial pneumonia. The argument that the case-management steps may lead to antimicrobial misuse should be refuted by recording current antibiotic overuse and improper usage by doctors and other health professionals. Although there is a renewed interest in focusing treatments at the community level, our research reveals that this may not be the most cost-effective approach. When combined with enhanced care-seeking behavior treatments, acute respiratory infections case management at the first-level institution may still be the most cost-effective.