epidemiology of respiratory infections - humsc

Epidemiology of Respiratory infections

Associate Professor Dr Eman Al-Kamil

Community Medicine

Hashemite University

4/7/20211 Associate Professor Dr Eman Al-Kamil

Respiratory infections are a frequent burden to health even though cost-effective methods for their prevention and cure are available.

Acute respiratory infections in children under 5 years of age are the most frequent cause of death from lung disease globally, causing more than 4 million deaths annually.

Tuberculosis is the most frequent cause of death from a single pathogen in persons aged 15 to 49 years (a total of 2 million to 3 million deaths annually).

Respiratory infections are the most frequent complications of immune deficiency (whether due to HIV infection or induced by chemotherapy) and in diabetic patients.


Respiratory tract infection refers to several infectious diseases involving the respiratory tract.

An infection of this type is normally further classified as :

1. an upper respiratory tract infection (URI or URTI) or

2. a lower respiratory tract infection (LRI or LRTI).

Lower respiratory infections, such as pneumonia, tend to be far more serious conditions than upper respiratory infections, such as the common cold.


Upper respiratory tract infectionTypical infections of the upper respiratory tractinclude tonsillitis, pharyngitis , laryngitis, sinusitis, otitis media, certain types of influenza, and the common cold.

Symptoms of URIs can include cough, sore throat, runny nose, nasal congestion, headache, low grade fever, facial pressure and sneezing.

Lower respiratory tract infectionLower respiratory tract infections are generally more serious than upper respiratory infections. LRIs are the leading cause of death among all infectious diseases.

The most common LRIs are bronchitis, bronchiolitis and pneumonia.

Influenza affects both the upper and lower respiratory tracts, but more dangerous strains such as the highly pernicious H5N1 tend to bind to receptors deep in the lungs. 4/7/20214 Associate Professor Dr Eman Al-Kamil

Epidemiology

❖Respiratory tract infections (RTIs) are the most common, and potentially

most severe, of infections treated by health care practitioners.

❖Lower RTIs along with influenza, are the most common cause of death by

infection.

❖Upper respiratory infections are one of the most frequent causes of doctor's

visits .

❖upper respiratory infections are the most common illness leading to missing

school or work absence.

❖Although upper respiratory infections can happen at any time, they are most

common in the autumn and winter months, from September until March.

❖This may be explained because these are the usual school months when

children and adolescents spend a lot of time in groups and inside closed doors.

❖Transmission is via

- respiratory droplets or by

- virus-contaminated hands4/7/20215 Associate Professor Dr Eman Al-Kamil

➢Vast majority of upper respiratory infections are caused by

viruses and are self limited.

➢Antibiotics are rarely needed to treat upper respiratory infections

and generally should be avoided, unless the doctor suspects a

bacterial infection.

➢Simple techniques, such as, proper hand washing and covering face while coughing or sneezing, may reduce the spread of upper

respiratory infections.

➢ Most often, URI is contagious and can spread from person to

person by inhaling respiratory droplets from coughing or sneezing

by touching the nose or mouth by hand or another object exposed

to the virus.


Cause

1. Viral :

Over 200 different viruses have been isolated in patients .

The most common virus is called the

❑ rhinovirus.

❑ coronavirus,

❑ influenza and parainfluenza virus,

❑Adenovirus, enterovirus,

❑respiratory syncytial virus.❑ SARS ( Severe Acute Respiratory Syndrome)❑Chickenpox (varicella ), ❑Measles (rubeola),❑Mumps, Rubella (German measles) and ❑Epstein-Barr virus (infectious mononucleosis)❑ Influenza viruses affect both upper and lower respiratory tracts. 4/7/20217 Associate Professor Dr Eman Al-Kamil

2. Bacterial :

❑Diphtheria , Corynebacterium diphtheria❑Group A streptococcus❑Haemophilus influenzae type b❑ Pneumococcal Pneumonia❑Pneumococcal meningitis❑ Tuberculosis, Mycobacterium tuberculosis.❑Whooping cough (pertussis), Bordetella pertussis❑Legionnaires' disease, Legionella pneumophila❑Anthrax


Risk factors for respiratory infection

1. Age , extremes of age (very young and elderly),sex, Legionnaire's disease more common in men

2. lack of breast feeding.

3. Ethnic group and country of origin ( high risk countries).

4. physical or close contact with someone with upper respiratory

infection;

5. poor hand washing after contact with an individual with upper

respiratory infection;

6. Overcrowding :close contact with children in a group setting,

schools or daycare centers;4/7/20219 Associate Professor Dr Eman Al-Kamil

4/7/2021Associate Professor Dr Eman Al-Kamil10

7. Social history:a) smoking (may impair mucosal resistance and

destroy the cilia);

b) drug use, travelc) living condition , Overcrowding, d) Occupation :health care facilities, hospitals,

nursing homes; nosocomial infection .

8. immunocompromised state (compromised immune system) such as, HIV, organ transplant, congenital

immune defects, long term steroid use; and

9. anatomical abnormalities ,facial trauma, upper airway

trauma, nasal polyps.10 . Malnutrition 11. Air pollution

Epiglottitis and Laryngotracheitis➢Inflammation of the upper airway is classified as epiglottitis or laryngotracheitis (croup) based on the location, clinical manifestations, and pathogens of the infection.

➢Haemophilus influenzae type b is the most common cause of epiglottitis, particularly in children age 2 to 5 years.

➢Epiglottitis is less common in adults.

➢Some cases of epiglottitis in adults may be of viral origin. Most cases of laryngotracheitis are due to viruses.

➢More serious bacterial infections have been associated with H influenzae type b, group A beta-hemolytic streptococcus and Corynebacterium diphtheriae.


When should you seek medical care for upper respiratory

infection?

Most people tend to diagnose and treat their symptoms

at home without seeking professional medical care.

A great majority of cases of upper respiratory infection are caused

by viruses and are self-limited, meaning they resolve on their own

spontaneously.

Visiting a doctor may be advisable if:

symptoms last more than a couple of weeks,

symptoms are severe and worsening,

there is difficulty breathing,

swallowing is impaired, and

upper respiratory infection is recurring.


Prevention of upper respiratory infection

There are several measures that can reduce the risk of infections in

general.

1. Breast feeding helps strengthen the immune system of infants by

transferring the protective antibodies from the mother's milk to the

baby.

2. hand washing is especially encouraged during the cold seasons

(fall and winter) or handling others with the infection;

3. reducing contact with people who may have the infection (people

may carry and spread the virus a few days before they have

symptoms and a few days after their symptoms have resolved);

4. proper cleaning of common objects (fomites) that are touched by

individuals who may be infectious such as, telephones, refrigerator

door, computers, stair railings, door handles, etc.;

5. covering mouth and noise when coughing or sneezing; and

6. vaccination with flu vaccine as recommended for certain people

(elderly, people with chronic medical conditions, health care

workers, etc.) and H influenzae type b vaccine (Hib).4/7/202113 Associate Professor Dr Eman Al-Kamil

Lower respiratory tract infection:

It includes :

1. pneumonia,

2. lung abscess and3. Bronchitis and Bronchiolitis4. Tuberculosis

Symptoms include shortness of breath, weakness, high fever,

coughing and fatigue.

Lower respiratory tract infections place a considerable burden on

the health budget and are generally more serious than upper

respiratory infections.

However ,they were still the leading cause of deaths among

all infectious diseases, and they accounted for 3.9 million deaths

worldwide and 6.9% of all deaths that year.


Bronchitis and Bronchiolitis

• Bronchitis and bronchiolitis involve inflammation of the bronchial tree.

• Bronchitis is usually preceded by an upper respiratory tract infection or forms part of a clinical syndrome in diseases such as influenza, measles, rubella, pertussis, and scarlet fever .

•

• Chronic bronchitis with a persistent cough and sputum production appears to be caused by a combination of environmental factors, such as smoking, and bacterial infection with pathogens such as H influenzae and S pneumoniae.

• Bronchiolitis is a viral respiratory disease of infants and is caused primarily by respiratory syncytial virus. Other viruses, including parainfluenza viruses, influenza viruses and adenoviruses (as well as occasionally M pneumoniae) are also known to cause bronchiolitis.


Pneumonia

➢ It is classified as either community or hospital

acquired depending on where the patient contracted

the infection.

➢ It is life-threatening in the elderly or those who are

immunocompromised.

➢ The most common treatment is antibiotics, and these

vary in their adverse effects and their effectiveness.

➢ Pneumonia is also the leading cause of death in

children less than five years of age.

➢ The most common cause of pneumonia is

pneumococcal bacteria, Streptococcus

pneumoniae accounts for 2/3 of bacterial

pneumonias.


Prevention

1. Vaccines can help in prevention of pneumonia in children,

the elderly and those with chronically debilitating conditions

or diseases such as HIV.

The pneumococcal vaccine prevents the most common

form of bacterial pneumonia, Streptococcus pneumoniae.

A flu vaccination can help in prevention of an illness that

would develop into pneumonia

The Hib vaccine prevents pneumonia in children from

Haemophilus influenzae type b.

2. Smoking secession , because it damages the lungs' natural

defenses against disease.

Quitting smoking is recommended to prevent both pneumonia

and bronchitis, as well as limiting exposure to air pollutants and

washing hands regularly to avoid spreading infections and

viruses. 4/7/202117 Associate Professor Dr Eman Al-Kamil

3. Implementation of case-management algorithms developed by the World Health Organization (WHO), and evidence indicates that these protocols have helped to reduce the number of deaths due to ALRI.❑Protocols for the management of ALRI have been incorporated to train providers at the primary care level to better manage the conditions of children .

❑ALRI guidelines train providers to look for two key clinical signs: ▪ elevated respiratory rate and▪ inward movement of the lower chest wall on breathing.▪Community health workers with basic training in the protocol use an algorithm to diagnose bacterial ALRI cases that require antibiotic treatment and referral for hospital.



Legionnaire's disease➢ It is a form of atypical pneumonia caused by any type

of Legionella bacteria, i.e Legionella pneumophila.➢ Under reporting is believed to occur, about 90 percent of

cases of Legionnaires' disease are missed.➢ The bacterium is found naturally in fresh water.➢ L. pneumophila thrives in aquatic systems

➢ It can contaminate hot water tanks, hot tubs, and cooling towers of large air conditioners.

➢ It is usually spread by breathing in mist that contains the bacteria.

➢ It can also occur when contaminated water is aspirated.

➢ It typically does not spread directly between people and most people who are exposed do not become infected.


Incubation Period : 2-10 DaysRisk factors• Increasing age, especially over 45• Gender; men • Smokers, alcoholics• Chronic respiratory or kidney disease • Diabetics, poor immune function, cancer sufferersTransmission • Cooling systems (if applicable)• Domestic water services

➢Hot water systems➢Cold water systems

• Spa Baths• outbreaks do occur, they are usually in the summer and early

autumn.• The fatality rate of Legionnaires' disease has ranged from 5–

30% during various outbreaks and approaches 50% for nosocomial infections

Treatment of Legionnaires' disease is

with antibiotics .

Recommended agents

include fluoroquinolones, azithromycin

, or doxycycline.

https://en.wikipedia.org/wiki/Nosocomial_infections

https://en.wikipedia.org/wiki/Antibiotic

https://en.wikipedia.org/wiki/Fluoroquinolone

https://en.wikipedia.org/wiki/Azithromycin

https://en.wikipedia.org/wiki/Doxycycline

Respiratory Syncytial Virus

RSV is a highly contagious virus infection that most commonly

causes illness during the winter season.

Most children who develop an RSV infection have mild

symptoms of fever, nasal congestion, and nasal discharge.

High-risk groups are more likely to have more severe disease

process, including wheezing (bronchiolitis in infants) and/or

pneumonia. Such high-risk groups include:

▪ premature infants,

▪ children with a compromised immune system,

▪congenital/acquired cardiac disease and

▪ malnutrition.4/7/202121 Associate Professor Dr Eman Al-Kamil

http://www.medicinenet.com/script/main/art.asp?articleKey=2042

Whooping Cough (pertussis) (100 days ‘cough)

➢Bacterial disease, Specific to Humans

➢Severe in children <1 yr.

➢Most death occur in children <1 yr.

➢Causative agent: Bordetella pertussis

➢Mode of transmission: Air born infection

➢Source of infection: infected persons.

➢ Incubation period : 7–10 days, with a range of 4–21 days4/7/202122 Associate Professor Dr Eman :

Pertussis Infection


Incubation period : 7-21 days3 Stages

1st Stage- Catarrhal Stage 1-2 weeks2nd Stage- Paroxysmal Stage 1-6 weeks3rd Stage- Convalescent Stage weeks-months


➢Lead to death in 3% of cases➢ Cause cerebral damage (encephalopathy) in 2% of cases.➢Preventable disease by immunization.

Clinical features:❑ Fever

Catarrhal Stage❑ Rhinorreoh ❑ Cough :sever paroxysmal , coughing spasm with a characteristic “whooping ” sound →child trying to catch his breath before the next coughing.

❑Difficulty in breathing

❑vomiting after sever cough4/7/202125 Associate Professor Dr Eman Al-Kamil

Prevention:Immunization : pertussis vac. is given with diphtheria & tetanus vac(DPT).❑Killed vac., Dose 0.5 ml❑3 doses achieve 90% protection, given intramuscular.❑Vac. should not be given after the age of 6 yrs.

Side effects: oFever & ConvulsionContraindications:

History of sever reaction after the 1st dose, so the child given only diphtheria & tetanus vac ( DT).

history of convulsion after the 1st dose.Family history of epilepsy

Treatment -Antibiotic, Erythromycin may decrease the severity of the disease - Antipyretics :to decrease fever .


DiphtheriaDiphtheria is a disease with high fatality rate (5-10 %).Bacterial infectionCausative agent : Coranybacteria diphtheria.The microorganism secret toxins which cause cardiac

complication /or paralysis.Stridor

If not treated the child could die from suffocation Thick gray membrane coating the back of the throat

Incubation period: 2-5 days.Mode of infection: spread by direct

physical contact or breathing the aerosolized secretions of infected individuals

Source of infection: infected person4/7/202127 Associate Professor Dr Eman Al-Kamil


Diphtheritic croupLaryngeal diphtheria can lead to a characteristic swollen neck and throat, or "bull neck". The swollen throat is often accompanied by a serious respiratory condition, "barking" cough, stridor, hoarseness, and difficulty breathing, and historically referred to variously as "diphtheritic croup“, true croup", or sometimes simply as "croup".

Prevention:-Immunization , diphtheria vac.included with the DPT vac.

Tuberculosis : Global TB ReportAbout 9 million new cases in 2004

− 16 million prevalent cases− 98 % in developing countries

Increasing rates in Africa and Eastern Europe− Decreasing elsewhere

1.9 million deaths / yr− Leading cause of death in people with HIV

Progress in case detection, but >50% still not diagnosed and treated!Reservoir of infection : humans ,cattle− Virtually all transmission is person to personIncubation period: 2-6 – 12 weeksTwo-stage process− Initial infection with M. tuberculosis ( primary)− Progression from infection to disease 4/7/202129 Associate Professor Dr Eman Al-Kamil

Risks for initial infection− Source case factors

− Environmental factors

− Recipient factors

➢Risk factors – Close contact,– Duration of contact– Severity of disease, cough, cavities

Risks for disease once infected− Inoculum size (infective dose)− Cellular immunity- Overcrowding- malnutrition

Exposure(close contact)

No infection % 70

Infection 30%


Diagnostic Standards for TuberculosisLatent TB:Tuberculin skin test : intradermal injection of 0.1 ml of tuberculin purified protein derivative (PPD) into the inner surface of the forearm, the injection should produce a pale elevation of the skin (a wheal) 6 to 10 mm in diameter. The skin test reaction should be read between 48 and 72 hours after administration.An induration of 5 -10 or more millimeters is considered positive

Active TB➢CXR➢Sputum smear, Sensitivity 50%➢Sputum culture➢Clinical criteria


Directly Observed Therapy− Supervision of all doses of TB medication by a health team member

Directly Observed Therapy, Short Course (DOTS)− WHO policy for TB control, with programmatic imperatives to strengthen TB control efforts

What Is DOTS?❖Governmental commitment to TB control❖System for registration and follow-up of TB cases❖Reliable supply of TB drugs❖Microbiologic confirmation of TB diagnosis❖Supervision of at least the initial phase of TB therapy


What Can DOT(S) Do?1. Increase treatment completion rates

2. Reduce the emergence of drug-resistant TB

3. Improve cost-effectiveness of TB control

4. In conjunction with other interventions, reduce TB incidence.

The preferred regimen for treating adults with TB remains a regimen consisting of :A - intensive phase of 2 months of isoniazid (INH), rifampin

(RIF), pyrazinamide (PZA), and ethambutol (EMB) followed by:

B- a continuation phase of 4 months of INH and RIF.4/7/202133 Associate Professor Dr Eman Al-Kamil

Challenges in the Control of Tuberculosis1. HIV epidemic (dual infection)

2. Multidrug-resistant tuberculosis (MDR-TB)

3. Health system weaknesses and lack of political will.

BCG* for Prevention of TBLive attenuated vaccine derived from M. Bovis early 1900s by Calmette and Guérin.BCG is given as a single intradermal injection at the insertion of the deltoid.


Strategies for Control of Tuberculosis: Limitations1- Detection and treatment of cases

− Poor diagnostic capabilities

− Poor compliance with treatment

− Emergence of drug resistance

− HIV epidemic

2- Treatment of latent infection− Resources for screening and treatment

3- Vaccination− Current vaccine doesn’t prevent disease or transmission


epidemiology of respiratory infections - humsc

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