Respiratory infection - Introduction, Causes, Signs and Symptoms, Prevention, Diagnosis and Treatment

What is Respiratory Tract infection? Acute Respiratory infection, Chronic Respiratory infection, 

Acute Respiratory Infections (ARD)

Acute respiratory infection indicates infection of any part of the respiratory tract of less than 30days duration and otitis media of less than 14days duration.

The infection mainly includes acute episodes of cough, cold, running nose, hoarseness of voice, ear discharge, fast breathing, breathing difficulty and chest indrawing with or without fever.

A severe infection that prevents normal respiratory function is an acute respiratory infection. It typically starts in the nose, trachea (wind pipe), or lungs as a viral infection.

It can spread to the entire respiratory system if the infection is not treated. Acute respiratory infection prevents oxygen from being absorbed by the body which can lead to death. People suffering from this disorder urgently need medical assistance.

Classification of ARI: Acute respiratory infections are divided into

Upper respiratory tract (AURI)

Lower respiratory tract infections (ALRI).

a) Upper respiratory tract infections (AURI): Upper respiratory tract infections mainly include common cold, pharyngitis, otitis media.

b) Lower respiratory tract infections (ALRI): Lower respiratory tract infections mainly include epiglottitis, laryngitis, bronchitis, bronchiolitis and pneumonia.

 

a) Upper Respiratory Tract Infections (AURI)

i). Common Cold

Common cold is a mild upper respiratory tract viral illness. It is generally treated as a self-limited illness that will go away without any treatment.

Common cold is one of the most frequent acute illness that is observed in most of the people. In a year a person is affected with cold on an average of 2 or 3 times.

It is caused by many types of viruses.

Causative agent

Rhinoviruses are the most common virus which mainly cause common cold.

The virus can spread through droplets coming out from infected person when sneezes, coughs or talks.

Incubation period:

Incubation period is generally 24 to 72 hours, from the time of contact until the symptoms appears.

Mode of transmission

Common cold viruses can spread mainly by 3 mechanisms:

(a) Direct contact: Cold mainly spreads from one person to another through hands. The virus can stay on the skin for at least 2 hours. If an infected person having cold, shakes someone's hand then the virus is transmitted from person to person.

(b) Indirect contact: When an infected person is touching any surface with hands after sneezing then the virus survives on the surface for many hours. Then if the surface is touched by healthy person then the person is affected.

(c) Inhaling viral particles: When an infected person sneezes, the droplets containing viral particles can shed out in to the air. The viral particles can transmit to another person if they stand close and the droplets touches the persons eye, nose and mouth from the infected person.

Symptoms

• Congestion

• Sneezing

• Cough

• sore throat

• rhinitis (running nose) and malaise.

• Fever is observed in children and absent in adults.

ii). Pharyngitis

Pharyngitis is defined as the inflammation of the pharynx. It is simply called as "sore throat." It mainly causes scratching sensation in the throat and difficulty in swallowing.

Pharyngitis is the most common reason for visiting doctors. It occurs mostly in colder months of the year.

Causative agent:

Viruses such as influenza, corona, para influenza are the main causes of pharyngitis.

Other viruses like herpes, coxsackie, Epstein-Barr virus also cause pharyngitis.

Some viruses like rhinovirus may cause throat irritation along with the nasal secretions.

Incubation period: 2 to 5 days.

Modes of Transmission

When a healthy person was in direct contact with the infected person than the pharyngitis transmission occurs.

Prevention of pharyngitis

(a) Sharing food, drinks with others should be avoided.

(b) Infected person who are sick should be avoided.

(c) Before and after eating we should wash our hands. We have to wash our hands after coughing and sneezing.

(d) Hand sanitizer's with alcohol should be used when the soap and water are not available to clean the hands.

Signs and symptoms:

• Sneezing

• Headache

• chills, fever, cough

• fatigue, runny nose,

• scratchy throat

• sore throat.

b) Lower Respiratory Tract Infections (ALRI)

i). Epiglottitis

Epiglottitis is defined as the inflammation of the epiglottis and the adjacent supraglottic area.

If not treated, epiglottitis can lead to life-threatening airway obstruction. Epiglottis is a small movable lid like structure present above on the larynx and it mainly prevents the food and drinks from entering in to windpipe. It is a leaf shaped flap of cartilage located behind the tongue. It is connected to the thyroid cartilage and hyoid bone by ligaments.

Causative agent:

Haemophilus influenzae type b (Hib) bacteria are the main cause of inflammation.

Other viruses and bacteria which cause inflammation of the epiglottis are Streptococcus A, B and C, Staphylococcus aureus and Streptococcus pneumoniae.

Modes of transmission:

Haemophilus influenzae type b (Hib) bacteria mainly spreads through droplets of infection when an infected person cough or sneeze in to the air.

Infectious epiglottis is a cellulitis of the epiglottis, aryepiglottic folds and other adjacent tissues. If the droplets of infection enter or invade in to the epithelial layer then the bacterial infection begins.

Inflammation of the epiglottis mainly leads to edema and accumulation of inflammatory cells in the space between the squamous epithelial layer and the epiglottal cartilage.

The lingual surface of the epiglottis and peri epiglottic tissue have an abundant network of lymphatic and blood vessels that mainly facilitates the spread of infection and the subsequent inflammatory response.

Symptoms

Common symptoms observed are severe

• Sore throat

• Pain

• Difficulty in swallowing

• Fever and restlessness

Symptoms in adults

• Muffled or hoarse voice

• Severe sore throat

• Difficulty in swallowing and fever

ii). Laryngitis

Laryngitis is defined as inflammation of larynx (voice box) due to infection or irritation of larynx. Due to over use of larynx it also leads to inflammation.

Laryngitis is very painful and frustrating. Larynx is defined as framework of cartilage, muscles and mucous membranes that forms the entrance of trachea (wind pipe). Larynx consists of vocal cords- 2 folds of special lining of mucous membrane covering muscle and cartilage which is located behind Adam's apple.

Normally vocal cords open and close smoothly by forming sounds through their vibration and movement. When the vocal cords are inflamed and irritated it leads to distortion of vocal sound. As a result, voice sounds hoarse, rough or can become so faint.

Laryngitis is divided into 2 types;

(a) Acute laryngitis (short living)

(b) Chronic laryngitis (Chronic living). Causes

Most common causes of laryngitis are viral infection. It may also occur due to other diseases like cold, flu or pneumonia. Other irritants like alcohol, allergies, smoking, direct trauma can also cause laryngitis. Gastroesophageal Reflux Disease (GORD) also produce laryngitis.

In adults, other causes of chronic hoarseness may also include sores on vocal cords, lumps and bumps on vocal cords or stretching of vocal cords due to age or incorrect voicing techniques.

Signs and symptoms:

Laryngitis mainly include symptoms like

• weak voice or loss of voice quality

• tickling sensation

• hoarseness

• sore throat

• dry cough

• pain in swallowing

• feeling of a lump in the throat

• irritation and rawness of throat