Airborne diseases

General principles
(air-borne disease)
Dr. Vishwajeet Chavan
Assoc. Professor
Community Medicine

Introduction
• Respiration is a vital and constant activity.
• A person cannot stop breathing for longer than a few minutes
without serious effects on the brain and other vital organs.
• During normal respiration, a person breathes in about 500 mL of
air.
• Based on this, the volume of air that a person breathes in and
out in a day is about 14,400 liters.
• Quality of air (presence of contaminants due to industries/
infected person) plays an important role in the health of the
community as the same air is inhaled by all the people in the
community.
GEN. PRINCIPLES-AIRBORNE DISEASES 2

Definition
Airborne diseases are defined as-
"the diseases caused by pathogenic organisms that
remain suspended in the air (on dust particles,
respiratory and water droplets) and transmitted from
person-to-person via coughing, sneezing, talking,
laughing and close personal contact or aerosolization
of the pathogenic microbes"

CHARACTERISTIC OF AIRBORNE DISEASES
• Transmission of airborne diseases can occur by two
means of aerosolization:
-Airborne transmission
-Droplet transmission

1. Airborne transmission
• Airborne transmission is
defined as-"the
transmission of infection
by expelled particles that
are comparatively smaller
in size and thus can
remain suspended in air
for long periods of time‘’

• Airborne particles are particularly worrisome because they
can remain suspended in the air for extended periods of time.
• Airborne diseases have potential to spread across large
geographical areas in short span of time to cause epidemics
and pandemics.

2. Droplet transmission
• Droplet transmission is defined as-
"the transmission of diseases by expelled particles that are likely
to settle to a surface quickly, typically within 03 ft. of the
source".
• A susceptible individual contracts the droplet (containing the
infectious microorganism) in respiratory tract/ eyes/ mouth/ nasal
passages.

Common airborne diseases
Acute respiratory infections (Pneumonia)
Chickenpox
Measles (Rubeola)
Mumps
Rubella
Influenza (Seasonal/Swine/Avian flu, SARS)
Tuberculosis
Diphtheria
Whooping cough (Pertussis)
Meningococcal meningitis
Covid-19 (Novel Coronavirus induced Disease)

Mortality
• Acute respiratory infections (ARI) are the most common chronic
disease of children across the globe with 40 lakh deaths per year.
• Pneumonia is the leading cause of death among under-05 children
and the greatest single contributor to the overall burden of disease
in the world.
• Covid-19 is responsible for around 60 lakh deaths till date (31
jan2022)

Case
scenario
• In May 1994, a lady traveled from Chicago to Honolulu
by flight and the journey lasted about 8 hours 45
minutes.
• She died a few months later and was diagnosed to have
Multi-Drug Resistant Tuberculosis (MDR-TB).
• Following this, the other people who had traveled on
the same flight were tested.
• Among all the people in that flight, 15 passengers were
found to be infected with Tuberculosis.
• Of these, 06 passengers did not have any other risk
factors to develop Tuberculosis. It was also observed
that they had sat on the same section of the plane as
the lady.'

Epidemiological triad
Agent
Host Environment

Agent factor (virus/bacteria) -
Airborne disease Causative agent
Common cold Rhinovirus
Chickenpox Varicella zoster
Measles, Mumps, Rubella Measles virus, Mumps virus, Rubella virus
Men. meningitis Neisseria meningitides A,B,C,W AND Y
Diphtheria Corynebacterium diphtheriae
Influenza Influenza virus type A/B/C
T.B. Mycobacterium tuberculosis
Pertussis Bordetella pertussis
Covid-19 Novel corona virus
pneumonia Streptococcus pneumonia

Host factors-
Vaccination status: Many airborne diseases are vaccine preventable.
Immunity: Immunocompromised individuals are more susceptible for
airborne diseases as well as have a risk of developing complications.
Age group: Airborne diseases like diphtheria, measles, mumps, and
rubella occur in children under 05 years.
Comorbidities/chronic illness: Individuals with comorbidities/chronic
illness like diabetes, asplenia (no spleen), cancer, has an increased risk
of contracting airborne diseases and its complications.

Occupation: The individual's occupation may make him/her susceptible for
airborne diseases. For example, individuals with silicosis are susceptible for
tuberculosis infection, healthcare professionals treating infectious patients (H1N1,
SARS, etc.) suffering from airborne diseases are themselves at risk of contracting
the airborne diseases.
Travel: Travelers especially frequent travelers are at increased risk of contracting
airborne diseases from infected co-travelers. Air travel enables individual coming
into contact with pathogenic organisms existing in far off places too.
Personal habits: Habits like smoking makes them more susceptible to airborne
disease like pulmonary tuberculosis infection and active tuberculosis.
Sex: Most airborne diseases do not have a predilection to sex and ethnicity.

Environment factor-
• Physical
 Particle size (i.e. the diameter of the particle): A particle with diameter of pm (airborne) is capable of
reaching the lower respiratory tract of humans and particle with diameter >51.1M (droplet) remains
suspended in air and aids transmission of airborne diseases.'
• Particle size is an important variable in airborne and droplet disease transmission because the ability of an
infectious disease to cause an infection depends on the concentration of the microorganism, the human
infectious dose, and the virulence of the organism."
 Level of infectious particles and the extent of desiccation: Humans can acquire devastating infectious
diseases through exposure to very low levels of infectious particles. For example, infectious dose of influenza
A for humans is very low, only a few cells of Mycobacterium tuberculosis are required to overcome
normal lung clearance and inactivation of defence mechanisms. A single sneeze can generate around
40,000 large droplet particles; most will desiccate immediately into small, infectious droplet nuclei, with
80% of the particles being smaller than 100 microns." 15
 The frequency of the initiating activity: A single sneeze may produce more total infectious particles than a
cough.

Physical factors contd..
 Temperature: An important factor which influences survival of
virus/bacteria. For example, a low temperature is or low
temperatures are ideal for airborne influenza virus survival and there
is a less chance of survival at higher temperatures. However,
bacteria are more resistant to temperature variations than viruses.
 Relative humidity: Relative humidity has an inconsistent relation
with survival of airborne bacteria, e.g. S. pneumoniae survives poorly
at intermediate relative humidity and pseudomonas survives at high
relative humidity.
 Ventilation: Poor ventilation favors increased density of
infectious particles and transmission of airborne diseases.

Social
 Overcrowding: Overcrowding can lead to close exposure to droplets, concentration of the atmosphere
with droplets, and infectious material.
 Proximity: Closeness to one another increases the risk of transmission of airborne diseases. Close contact
includes kissing/hugging/talking to someone within three feet, sharing eating or drinking utensils and
touching someone directly.
 Poverty: People living in poverty tend to live in poorly ventilated houses, have poor respiratory hygiene
and personal hygiene, poor immunity and inadequate access to health service, all of which may favor
transmission of airborne diseases and its complications.
 Urbanization: Increased density of population both at home and workplace increases the risk of
transmission of airborne diseases.
 Travel: Frequent travelers, air travelers, travelers in crowded transport vehicles are at increased risk of
contracting the airborne diseases as well as transmitting the diseases if they are infectious

Dynamics of transmission
Source of infection
•Infectious humans
•Air/dust/fomites containing
infectious material
•Air-conditioning systems.
Reservoir of infection
•Infected humans/animals
•Infective material
•Air with infected particles-
Droplets, Aerosols, Droplet
nuclei
•Lesions (skin and mucosa)
•Fomites
Portal of exit
•Oral cavity and
nasal cavity of
infected persons
Portal of entry
•Nasal cavity and
oral cavity of
susceptible persons
Mode of transmission
•Aerosolization of the
pathogenic microbes
•Coughing
•Sneezing
•Talking
•Laughing
•Close personal contact
•Vomiting
•Flushing the toilet
(aerosolization of toilet
water)

Clinical features
• Fever
• Chills
• Sore throat
• Running nose (Coryza)
• Headache
• Malaise
• Cough
• Bloodshot eyes (conjunctivitis)
• Difficulty breathing (dyspnea)
• Chest pain
• Neck stiffness
• Vomiting
• diarrhea

Clinical features contd…
Few of the airborne diseases may present with one or more of the
following complications:
 Hypoxemic respiratory failure
 Encephalitis
 Multiorgan dysfunction
 Septic shock
 Secondary bacterial and fungal infections

Diagnosis
• Airborne diseases are diagnosed based on:
 Signs and symptoms of disease: Most airborne diseases present typical c/f .
 History of close contact with infected person: Recent exposure/close contact
with infected persons or recent travel to outbreak areas provides
epidemiological linkage of cases.
 Laboratory diagnosis: Confirmation of diagnosis can be done by testing (e.g.
ELISA, RT-PCR, culture, virus isolation, etc.) the samples (e.g. nasal swab,
throat swab, sputum, swab from skin lesion, etc.) of suspected persons in the
laboratory.

Treatment
• Most of the airborne diseases are treated symptomatically and with
supportive treatment.
• Airborne disease patients need plenty of rest and fluids. Further
treatment depends on the specific disease.
•Some airborne diseases are treated with antibiotics or antiviral drugs
depending on the etiological agent, e.g. Covid-19, H1N1, antibiotics and
hospitalization for infants with whooping cough, and antitubercular drugs
to treat and cure TB.
•Failure to complete the course of medications can lead to drug resistance
and return of symptoms.

Prevention
• 1. General measures
• 2. Specific measures
• 3. Personal protective measures

1. General measures
 Personal hygiene: This can get rid of any infectious material that is
present on the skin surface following exposure.
 Hand washing and hygiene: This is the single most
important preventive measure against spread of airborne infections.
Measures include washing of hands with soap and water before and after
eating food and after using the toilet.

Contd…
• Hand drying: Use of disposable paper towels. Avoid cotton/linen
towels or air blowers installed in public toilets (spreads infection).
v Hand disinfection: Alcohol and other disinfectants supplied in spray
bottles.
 Sanitation and cleanliness: Ban on open air defecation, urination,
spitting in public places.

2. Specific measures
• Adequate ventilation: Ventilation plays a major role in the prevention of
airborne diseases. Adequate ventilation and cross-ventilation reduce the
concentration of the infectious agents in the room.
• Openings (Window & doors) in a living area should be at least one-fifth space of
the floor. In work areas where there cannot be open windows, mechanical
ventilation should be provided (Fan/ Air-cond. or coolers).
• It is advised that there should be a minimum of six air changes every hour.

Sp. Measures contd…
• Avoiding overcrowding: Overcrowding is a major factor for airborne disease
outbreaks in developing countries. Overcrowding can lead to close exposure to
droplets, concentration of the atmosphere with droplets and infectious material.
• A minimum floor area of 6 meter squares should be available for each person in the
living area.
• Overcrowding can be calculated based on two parameters—1.number of persons per
room and 2.square feet area per person.
• When in hospital wards, there is a minimum distance that is recommended between
two beds and this is usually 2 meters.

Sp. Measures contd..
• Immunization:
• Many airborne diseases can be prevented by timely
vaccination among susceptible humans, e.g.
• Covid-19, measles, mumps, rubella, diphtheria,
pertussis, H. influenzae, etc.

3. Personal protective measures
 Cough etiquette/Good respiratory hygiene: Covering the
mouth and nose when coughing or sneezing, using tissues
and disposing them correctly.
v Isolation: Early self-isolation of those feeling unwell,
feverish and having other symptoms of airborne diseases.
v Avoiding close contact with sick people.
v Avoiding touching eyes, nose or mouth.
v Regular hand washing and proper drying of hands.

Strategies to Prevent Airborne Disease
Transmission in Healthcare Settings
Guidelines of WHO and International Union of Tuberculosis
and Lung Disease, focuses on health care facilities for the
prevention and control of airborne diseases-
• Training and education of health care staff
• Infection control measures to be taken.
• Standard operating procedures for different cadres of health
care staff.
• Proper handling of infectious waste.

Measures to be taken in the out-patient department
 Well-ventilated waiting area and rooms for patients.
 Separation of waiting area and consultation room for those with
respiratory complaints.
 Health education to the patients regarding cough etiquette.

Measures to be taken in the in-patient department
• Provision of separate wards for respiratory diseases.
 Proper disposal of infectious waste.
 Early diagnosis and Prompt treatment.
 Educating the patients and family members regarding hygiene,
personal protection and avoiding overcrowding.

Personal protective measures for health care workers (HCW)
• Respiratory protection devices: These include surgical masks and specific
respirators (N95).These should be used by healthcare workers at high risk of
frequent exposure to airborne diseased patients.
• Disposable aprons/impermeable aprons: Prevents exposure of HCWs body
to droplets. These should be used while doing aerosolization procedures and
in isolation wards.
• Gloves: HCWs should wear gloves while collecting/handling infectious
specimens (e.g. throat swab) of airborne disease patients and direct handling
of the patients.
• Eye protection with goggles/face shield: These shall be worn by HCWs during
aerosolization procedures, collection of specimen and in isolation wards.

Environmental control
Quarantine and isolation:
This shall be followed for airborne diseases based on their
potential of causing outbreaks and known period of
communicability and incubation period.

Regulations
• International and National regulations for prevention and control of various
airborne diseases especially for the ones which have potential to cause epidemics
and pandemics.
• Public Health Emergency of International Concern (PHEIC) first time declared by
WHO in 2009 in the context of rapidly spreading Pandemic Influenza A (H1 NI)
2009.

International Health Regulations (IHR), 2005
• As per IHR, 2005, Public Health Emergency of International Concern (PHEIC) is
defined as "an extraordinary event which is determined, as provided in these
regulations:
i. to constitute a public health risk to other States through the international
spread of disease; and
ii. to potentially require a coordinated international response’

IHR 2005 CONTD…
• It considers prevention, protection, response, and containment
of an event in such a manner that is fully aligned with human
rights preservation and avoidance of unnecessary interference
with international travel and trade.'' As an international treaty,
the IHR are legally binding; all countries must report events of
international public health importance.

The Factories Act, 1948
• The Factories Act is an Act laid out by the Government of India.
It focuses on all persons working in an establishment that
employs more than 10 people.
• It provides various directions to maintain the health of all
employees.
• Certain sections of the Act focus on ventilation, management of
dust, and use of personal protective equipment.

National Health programs
• The Universal Immunization Program (UIP) is a program that focuses on
immunization of infants and children (under 05 yrs. Of age) against various
vaccine preventable diseases including airborne diseases like Tuberculosis,
Diphtheria, Pertussis, Influenza, Measles, Rubella.
• Complete immunization of children for these diseases ensures prevention of the
mortality rate in under-five children.

RNTCP
• Revised National Tuberculosis Control Program (RNTCP) provides for the early
diagnosis and treatment of tuberculosis at the primary health care level.
• Thus, making it easily accessible to all the populations.
• DOTS centers and Designated Microscopy Units help in the proper disbursal of
adequate treatment and for diagnosis using methods like sputum microscopy, X-
rays, and Cartridge Based Nucleic Acid Amplification Technology (CBNAAT).

Airborne diseases

More Related Content

What's hot

Similar to Airborne diseases

Recently uploaded

Airborne diseases