Communicable Diseases

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Introduction

According to the World Health Organisation “over 13 million people die each year from Infectious and Parasitic Diseases: One in two deaths in some developing countries. Poor people, women, children, and the elderly are the most vulnerable. Infectious diseases continue to be the world’s leading killer of young adults and children” .

Socioeconomic, environmental and behavioural factors, as well as international travel and migration, foster and increase the spread of Communicable Diseases. Vaccine-preventable, foodborne, zoonotic, health care-related and communicable diseases pose significant threats to human health and may sometimes threaten international health security .

According to Lindahl and Grace (2015) communicable diseases have had civilisation-altering consequences throughout history. An estimated 50–100 million humans worldwide succumbed to infection during the Spanish Flu Pandemic in 1918–1920. While rinderpest was in part responsible for death by starvation of almost two-thirds of the East African Massai population after it caused massive death to livestock. 

As a result of better living conditions, increased access to health care including better vaccines, advent of antibiotics and improved surveillance and monitoring in relation to public health, the proportion of infectious diseases was tredning downwards during the early Twentieth Century, however, an increase in the emergence and re-emergence of infectious diseases became evident in many parts of the world towards teh later part of the Twentieth Century.  

Weiss & McMichael (2015) hightlight that over 30 new, emerging diseases have been identified, including Legionnaires' Disease, Human Immunodeficiency Virus (HIV) / Acquired Immune Deficiency Syndrome (AIDS), Hepatitis C, Bovine Spongiform Encephalopathy (BSE) / Variant Creutzfeldt-Jakob Disease (vCJD), several Viral Hemorrhagic Fevers and, most recently, Severe Acute Respiratory Syndrome (SARS), Avian Influenza, Ebola and Zika Virus and in part relate the emergence of these diseases, and resurgence of old ones like Tuberculosis andCcholera to various changes in human ecology including rural-to-urban migration resulting in high-density peri-urban slums; increasing long-distance mobility and trade; the social disruption of war and conflict; changes in personal behavior; and, increasingly, human-induced global changes, including widespread forest clearance and climate change. 

What are Communicable Diseases

Communicable diseases are those that are spread from one person to another through a variety of methods. Socioeconomic, environmental and behavioural factors, as well as international travel and migration, foster and increase the spread of Communicable Diseases. Vaccine-preventable, foodborne, zoonotic, health care-related and communicable diseases pose significant threats to human health and may sometimes threaten international health security .How these diseases spread depends on the specific pathogen or infectious agent and means of transmission: 

Pathogens

Bacteria

• These one-cell organisms are responsible for illnesses such as strep throat, urinary tract infections and tuberculosis. Bacteria constitute approximately 38% of human pathogens, and 30% of the emerging pathogens in humans.  

Viruses

• Even smaller than bacteria, viruses cause a multitude of diseases. According to Lindahl & Grace (2015) it is estimated that 44% of the diseases considered emerging in humans are viral. Emerging Infecttious Diseasese that that have received most publicity in the past 30 - 40 years have been viruses. Notable examples have been HIV, SARS, and Ebola.  

Fungi

• Many skin diseases, such as ringworm and athlete's foot, are caused by fungi. Other types of fungi can infect your lungs or nervous system.  
  

Parasites

• Malaria is caused by a tiny parasite that is transmitted by a mosquito bite. Other parasites may be transmitted to humans from animal feces.  

Prions

Transmission

Direct Contact

Person to Person: 

• Physical Contact with an infected person, such as through Touch (e.g. Staphylococcus), Sexual Intercourse (e.g. Gonorrhea, HIV), Fecal/Oral Transmission (Hepatitis A), or Droplets (Influenza, Tuberculosis)

Animal to Person: 

• Bites from infected insects or animals capable of transmitting disease (e.g. Mosquito: Malaria, Zika Virus and Yellow Fever; Flea: Plague; Tick: Lyme Disease); and handling of animal waste (e.g. Toxoplasmosis)

Mother to Unborn Child:

• Infecttious Disease may be trasmitted to the unborn child through the placenta or during passage through the vaginal canal during the birth process.

Indirect Contact

• Contact with a contaminated surface or object (Norovirus), Food (Salmonella, E. Coli), Blood (HIV, Hepatitis B), or Water (Cholera);
  
• Travel through the air (e.g. Tuberculosis or Measles)

Refresh your knowledge of some common communicable diseases:
• Pneumonia
• HIV/AIDS
• Tuberculosis
• Malaria

Review your knowledge of Antibiotic Resistant Diseases which are frequent within the Hospital Setting.
• Methicillin-Resistant Staphylococcus Aureus (MRSA)
• Clostridium Difficile Infection (CDif)

You can also check out our Infectious Disease Category which provides information on many other infectious conditions:
• Infectious Diseases

Risk Factors

Some predisposing factors of contracting infectious diseases can be anatomical, genetic, general and disease specific. Climate and weather, and other environmental factors that are affected by them, can also predispose people to infectious agents. Other factors such as overall health, age and diet are important considerations in the prevention of spreading infectious diseases .

Figure.1 Factors Leading to Increases in the Number of Susceptible Individuals

Figure.2 Factors Leading to Increased Exposure to Infectious Diseases

Figure.3 Factors Contributing to Increased Infectivity

Modifiable Risk Factors

Refer to characteristics that individuals or societies can change to reduce risk of infectious disease and improve health outcomes. WHO typically refers to four major ones for Commuicable Disease: Hygiene, Vaccinations, Food Preparation methods and Overcrowding.

Overcrowding

• High Population Density provides greater opportunity for contact between infectious diseases and susceptible people which leads to higher transmission rates.
• Large Concentration of Population once an epidemic starts, it spreads faster which leads to higher transmission rates.
  
• According to WHO from a purely epidemiological perspective, providing sufficient residential space and avoid of overcrowding provide high-impact public health interventions to reduce rate of transmission of communicable disease

Types of Diseases:

• Airborne Droplet Diseases e.g. Measles, Meningitis, Acute Respiratory Infections, and Tuberculosis. 
• Faecal-Oral Diseases e.g. Diarrhoeal Diseases including Shigella and Cholera 

Inadequate Shelter

• Exposure to the elements increases risk of Hypothermia and Dehydration
• Exposure to Indoor Smoke increases risk of higher disease progression in those with Acute Respiratory Infections 

Insufficient Nutrient Intake

• Malnutrition leads to lower natural immunity, which often results in increased risk of infectious diesase and increased progression of disease
• Nutritional Crises can Precipitate Epidemics as lower immunity often means lower vaccine efficacy, and therefore  a higher susceptibility for transmission 

Insufficient Vaccine Cover

Poor Water, Sanitation and Hygiene

High Exposure to Disease

Lack of / Delay in Treatment

Signs & Symptoms 

Depending on the etiology (eg. virus, bacteria), the systems involved (e.g. respiratory, cardiovascular, central nervous system) and stage of disease (e.g. acute, chronic) the clinical manifestations of Communicable Diseases will vary widely and may be local to the site of infection (eg, cellulitis, abscess) or systemic (most often fever). Manifestations may also develop in multiple organ systems and severe, generalised infections may have life-threatening manifestations (eg, sepsis, septic shock).  

Cardiovascular 

• Tachycardia
• Bradycardia
• Hypotension
• Tachypnea
• Dyspnea
• Cough
• Hoarseness
• Sore Throat
• Nasal Drainage
• Sputum Production
• Oxygen Desaturation
• Decreased Activity/Exercise Tolerance

Central Nervous System 

• Altered Conciousness 
• Confusion
• Delirium
• Stupor
• Coma 
• Seizure 
• Headache 
• Photophobia 
• Memory Loss 
• Stiff Neck 
• Myalgia
  

Endocrinology

• Increased Thyroid-stimulating Hormone
• Increased Vasopressin
• Increased Insulin
• Increased Glucagon
• Hyperglycemia
• Hypoglycemia

Gastrointestinal

• Nausea
• Vomitting
• Diarrhea

Geniturinary

• Heamaturia
• Dysuria
• Oliguria
• Proteinuria
• Urgency
• Frequency

Haematology

• Increased Immature Neutrophils
• Increased Mature Neutrophils
• Release Granulocytes
• Increased Leukocytes
• Thrombocytopenia

Integumentary

• Purulent Drainage
• Skin Rash
• Red Streaks
• Bleeding from Gums
• Bleeding into Joints
• Erythema
• Joint Effusions

Systemic

• Fever
• Chills
• Malaise
• Enlarged Lymph Nodes
• Changes in Mental Status
• Fatigue 
• Lethargy
• Altered Appetite

Implications for Physiotherapy

As healthcare workers it is important that we recognise the symptoms of the most important infectious diseases and direct those affected to appropriate treatment as quickly as possible. It is also important to be aware of the role physiotherapy has in treating and advising patients presenting with these diseases (e.g. the benefits of exercise for patients with HIV/AIDS).

The statistics related to HealthCare Associated Infections make it clear Hand Hygiene in the healthcare environment is extremely important. As physiotherapists we need to learn how to use the alcohol hand rubs effectively and utilise these frequently. The WHO Guidelines identify 5 moments for Hand Hygiene:

1. Before Touching the Patient Why? Protect the patient from acquiring germs that might be on your hands. Clean your hands prior to personal care activities like bathing, dressing, brushing and oral care, as well as non-invasive observations (taking vital signs) and treatments.
2. Before Clean/Aseptic Procedure Why? Protect the patient from harmful germs, including their own, that could enter the body during procedures like needle insertions, medication administration and connecting to invasive medical devices like EEGs.
3. After Body Fluid Exposure Risk Why? Protect yourself and the patient’s surroundings from harmful patient germs generated via contact with fluids like blood, saliva, mucous, semen, tears or urine.
4. After Touching a Patient Why? Protect yourself and the immediate environment from harmful patient germs. After you touch a patient, you could have microorganisms on your hands that would get passed on to other patients.
5. After Touching Patient Surroundings Why? Protect yourself and the immediate surroundings from harmful patient germs.

Resources

Recent Related Research (from Pubmed)

References