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Communicable Disease Control Soili Larkin & Joshna Mavji Aim To understand key principles for communicable disease control 2 Communicable Disease Control Objectives • Define communicable diseases • Describe modes of transmission of communicable diseases • Describes measures of infection prevention • List key notifiable diseases • Outline the role of PHE Health Protection Teams in communicable disease control • Describe the process of responding to a case of communicable disease • Demonstrate awareness of key communicable diseases (Meningococcal disease, E. coli, Tuberculosis, Ebola) 3 Communicable Disease Control What are Communicable Diseases? Communicable diseases spread from one person to another or from an animal to a person. The spread often happens via airborne viruses or bacteria, but also through blood or other bodily fluid. The terms infectious and contagious are also used to describe communicable disease. 4 Communicable Disease Control Communicable Disease Control: Modes of Transmission Contact 5 Direct Direct physical contact (body surface to body surface) between infected individual and susceptible host. Examples: Influenza virus; Infectious mononucleosis; chlamydia. Precautions: Hand hygiene; masks; condoms. Indirect Infectious agent deposited onto an object or surface and survives long enough to transfer to another person who subsequently touches the object. Examples: RSV; norovirus; rhinovirus. Precautions: Sterilising instruments; disinfecting surfaces and toys in school. Droplet Via coughing or sneezing, or (in health care) during suctioning. Droplets are relatively large (>5 µm) and can be projected up to about one metre. Examples: Meningococcus; pertussis; scarlet fever Precautions: Masks; isolating case. Communicable Disease Control Communicable Disease Control: Modes of Transmission Noncontact 6 Airborne Transmission via aerosols (airborne particles <5µm) that contain organisms in droplet nuclei or in dusts. Examples: TB; measles; chickenpox; Precautions: Masks; negative pressure rooms in hospitals. Vehicle A single contaminated source spreads the infection (or poison). This can be a common source or a point source. Examples a) Point source: Food-borne outbreak from infected batch of food; b) Common source: A Listeriosis outbreak in Canada was linked to a meat production facility. It caused 20 cases across nationally. Cases may be widely dispersed due to transport and distribution of the vehicle. Precautions: Normal safety and disinfection standards. Vectorborne Transmission by insect or animal vectors. Example: Mosquitoes –malaria vector, ticks –Lyme disease vector. Precautions: Protective barriers (window screens, bed nets); insect sprays; culling animals. Communicable Disease Control Standard Infection Prevention Precautions Hand Hygiene Single most important part of infection control Hand washing before any contact with patients, after any activity that contaminates the hands, after removing protective clothing, after using the toilet and before handling food Decontaminating equipment: cleaning, disinfection and sterilization Preventing occupational exposure to infection Managing sharps injuries and blood splash incidents appropriately Isolation / Quarantine Use of personal protective equipment (PPE): gloves, aprons, eye protection, face masks etc. Correct disposal of excretions & soiled material Handling and disposing of sharps safely Disinfection, especially important in nurseries, schools & residential institutions Disposing of contaminated waste safely Managing blood and body fluids: spillages and transport of specimens Education Routine and selective immunisation Screening 7 Communicable Disease Control Notifiable Diseases (NOIDs) Acute encephalitis Infectious bloody diarrhoea Scarlet fever Acute infectious hepatitis Invasive group A streptococcal disease Smallpox Acute meningitis Acute poliomyelitis Anthrax Botulism Brucellosis Cholera Diphtheria Enteric fever (typhoid or paratyphoid fever) Legionnaires’ disease Leprosy Malaria Measles Meningococcal septicaemia Mumps Plague Rabies Food poisoning Rubella Haemolytic Uraemic Syndrome Severe Acute Respiratory Syndrome (SARS) 8 Communicable Disease Control Tetanus Tuberculosis Typhus Viral haemorrhagic fever (VHF) Whooping cough Yellow fever Other significant disease (diseases that may present significant risk to human health) Communicable Disease Control: Role of PHE Health Protection Teams • Protect the population from infection and environmental hazards through a range of core functions including: Surveillance and analysis of trends in communicable disease Operational support and advice to those involved in the prevention, investigation and control of infectious diseases and environmental hazards Education & training e.g. outbreak exercises Research 9 Communicable Disease Control Communicable Disease Control: Responding to a Case What investigations (microbiological / environmental / epidemiological) are needed to identify the agent, the cause of the incident? What is the source of infection? • Is it a continuing source that may need to be controlled? If so, what generic control measures can be applied to limit morbidity whilst awaiting confirmation e.g. enhanced hand washing, environmental cleaning etc. • Are there others exposed who may need advice / treatment? What is the likelihood of transmission? • Advice / prophylaxis to close contacts e.g. hepatitis B immunisation • Occupational transmission e.g. exclusion of food handlers with gastrointestinal infection Is public health action necessary? • How infectious is the source? - Is the index case at risk of a poor outcome? • Is the index case likely to pass the infection to others? - How close is the contact? • Do contacts and others exposed to the same source need to be traced? • How susceptible are those exposed? • Is there likely to be an ongoing source that needs controlling? 10 Communicable Disease Control Communicable Disease Control: Responding to a Case Does public health action need to be done immediately? Determined by: Possible interventions • Treatment of case • Prophylaxis • Seriousness of disease • Isolation • Transmissibility of infection • Hygiene advice • Length of incubation period • Exclusion • Vulnerability of people exposed • Closure of premises associated with incident • Public/ media / political reaction • Evidence based practice Communication • Cases / contacts / clinicians • Internal - specialist advice within PHE / microbiology • External - local authorities, press e.g. outbreak of meningococcal disease in a school 11 Communicable Disease Control Examples of Key Infections – Meningococcal disease Causal agent • Meningococcal meningitis and meningococcal septicaemia are systemic infections caused by the bacteria Neisseria meningitidis. Clinical features 12 • The infection may present as meningitis, septicaemia or a combination of both1. • Sudden onset of fever, malaise, increasing headache, nausea, vomiting, photophobia, neck stiffness, non-blanching rash Communicable Disease Control Examples of Key Infections – Meningococcal disease Reservoir • Humans Mode of transmission • Person to person, transmitted by droplet aerosol or secretions from the nasopharynx of colonised individuals • Transmission requires either frequent or prolonged close contract Incubation period • 2-10 days Period of communicability 13 • While live meningococci are present in discharges from nose and mouth. • Meningococci usually disappear from the nasopharynx within 24 hours of appropriate antibiotic treatment. Communicable Disease Control Examples of Key Infections – Meningococcal disease Epidemiology 14 • The majority of meningococcal infections occur in children under 5 years, with a peak incidence at 6 months of age. There is a smaller, secondary peak in incidence among young adults aged between 15-19 years of age. • Marked seasonal variation with the highest incidence occurring in winter • Most cases of meningococcal disease occur sporadically, with <5% of cases occurring in clusters. • Outbreaks are more common among teenagers and young adults in schools and university • Since the introduction of Men C vaccine into the UK routine immunisation programme the number of laboratory confirmed group C cases have fallen by over 90% among all age groups immunised. Cases among other age groups have fallen as a result of reduced carriage rates. • In the UK, serogroup B is now responsible for >85% of laboratory confirmed cases Communicable Disease Control Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Number of Cases Seasonal Trends in Meningococcal Disease 18 16 15 14 12 10 8 6 4 2 0 2010 Communicable Disease Control 2011 Year of Onset Confirmed Cases 2012 Three Week Rolling Average 2013 Examples of Key Infections – Meningococcal disease Public health management 16 • Indicated for confirmed or suspected cases • Trace close contacts: close household contacts (those with an overnight stay and/or +8hrs of continuous contact), intimate contacts • Antibiotic prophylaxis for close contacts - to eradicate nose and throat carriage (thus limiting further spread) and to eradicate carriage from those who may have recently acquired an invasive strain • Casual contacts such as those in a same school, nursery, party etc. are not usually offered prophylaxis • If the strain is found to vaccine-preventable, contacts are offered vaccination within 4 weeks of the case occurring Communicable Disease Control Examples of Key Infections – E. coli Causal agent • Many different strains of Escherichia coli can cause diarrhoeal illness • The most serious is verocytotoxic E.coli (VTEC) which can cause haemolytic uraemic syndrome (HUS) which can lead to renal failure and death. Clinical features • Diarrhoea (often bloody) • Abdominal cramps / pain • HUS is characterised by acute renal failure, haemolytic anaemia and thrombocytopaenia (lowered platelets). 17 Communicable Disease Control Examples of Key Infections – E. coli Epidemiology • Highest incidence rates in the UK occur in children < 5 years • Summer peak Reservoir • Gastrointestinal tract of animals – mainly cattle Mode of transmission • Consumption of contaminated, undercooked or raw foods, mainly beef • Consumption of unpasteurised milk • Cross contamination during food preparation • Person to person via faeco-oral route • Direct contact with animals e.g. school visits to farms • Waterborne transmission occurs through swimming in or consuming contaminated water. 18 Communicable Disease Control Examples of Key Infections – E. coli Incubation period • 2-10 days, median 3-4 days Period of communicability • Up to 1 week in adults, while excreting the pathogen • Up to 3 weeks in children, while excreting the pathogen Public health management • Minimisation of contamination at slaughter • Good kitchen hygiene and food preparation practices • Pasteurisation • Effective hand hygiene • Infection prevention precautions during farm visits • Protection of drinking water supplies • Good hygiene practices for swimming 19 Communicable Disease Control Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Number of Confirmed Cases Confirmed VTEC O157 Cases by Month in the West Midlands, 2009-2013 45 40 35 30 25 20 15 10 5 0 2009 20 2010 Communicable Disease Control 2011 2012 2013 Examples of Key Infections – Tuberculosis (TB) Causal agent • Mycobacterium tuberculosis Clinical features • Persistent cough lasting 3 weeks or more that may produce discoloured or bloody sputum. • Pain with breathing or coughing (pleurisy) • Weight loss • Symptoms of TB disease in other parts of the body depend on the area affected. 21 Communicable Disease Control Examples of Key Infections – Tuberculosis (TB) Reservoir • Primarily humans • In some areas diseased cattle, badgers, swine and other mammals are infected Mode of transmission • Person to person via inhalation of M. tuberculosis bacilli in droplet nuclei from coughing, sneezing and talking (requires close and prolonged contact) • Bovine TB is spread primarily through the ingestion of unpasteurised milk or milk products and in some cases through airborne transmission. Incubation period 22 • 3-12 weeks (from infection to reaction to tuberculin test). • Latent infection may be many decades Communicable Disease Control Examples of Key Infections – Tuberculosis (TB) Epidemiology • In 1993 the World Health Organization declared TB a 'global emergency'. • • 23 TB remains one of the world's leading infectious causes of death among adults. 1/3rd of the world's population is infected with the TB bacillus. • Leading cause of death among people who are HIV-positive. • Risk factors: Family/household contacts of cases diagnosed with TB (identified through contact-tracing), homelessness, history of alcohol/drug misuse, immigrants from high TB prevalence areas, individuals who frequently spend long periods of time in high TB prevalence areas, immunosuppression. • In the UK 2/3rds of TB disease is pulmonary which is the infectious form of TB. • 10% of those initially infected will eventually develop active TB disease. 90% of untreated infected individuals will never develop active TB (latent TB infection). • Bacilli survive in latent form which may reactivate in later life. The risk of reactivation increases with age, chronic disease and immunosuppression. Communicable Disease Control Examples of Key Infections – Tuberculosis (TB) Period of communicability • Most sputum smear positive cases stop being infectious after 2 weeks following appropriate treatment Public health management • Tuberculosis is a statutorily notifiable disease • In England and Wales enhanced TB surveillance started in January 1999. • In September 2005, a targeted BCG vaccination programme came into effect for: • • • 24 All infants living in areas where the incidence of TB is ≥40/100,000 population All infants with a parent or grandparent who was born in a country where the incidence of TB is >40/100,000 population. TB infection can be cured with appropriate antibiotic treatment. Communicable Disease Control Estimated TB incidence Rates, 2013 25 Communicable Disease Control Tuberculosis in the UK, 2013 Source: TB in the UK: 2014 Report https://www.gov.uk/government/publications/tuberculo sis-tb-in-the-uk 26 Communicable Disease Control Tuberculosis in West Midlands 27 Communicable Disease Control Examples of Key Infections – Ebola Virus Disease One type of viral haemorrhagic fever Causal agent • Ebola virus • A zoonotic virus Clinical features 28 • Initial: Fever, chills, aches and pains, malaise, lack of appetite • After 5 days: nausea, vomiting, watery diarrhea, abdominal pain • Additional symptoms: headache, conjunctivitis, hiccups, rash, chest pain, shortness of breath, confusion, seizures • Other possible infectious causes of symptoms: Malaria, typhoid fever, meningitis and other bacterial infections (e.g pneumonia) – all very common in Africa • Non-fatal cases typically improve 6–11 days after symptoms onset • Fatal disease associated with severe early symptoms. Case fatality rate – 50-90% • Intensive care, especially early intravenous fluids, may increase the survival rate Communicable Disease Control 29 Communicable diseases Communicable Disease Control Source: en.wikipedia.org Examples of Key Infections – Ebola Virus Disease Epidemiology • Ebola was first identified in 1976 in Sudan and the Democratic Republic of Congo following large outbreaks. Reservoir • Unknown – Primates and bats considered to be most likely reservoir Mode of transmission 30 • Spillover event from infected wild animals (e.g., fruit bats, monkey etc.) to humans, followed by human to human transmission • Person to person via contact with bodily secretions, organs and blood of infected individuals. • The handling of infected primates • Direct contact with the body of a deceased person infected with the virus. • Nosocomial transmission occurs frequently during outbreaks. • Sexual transmission following recovery from infection – virus isolated from semen upto three months after initial infection Communicable Disease Control Examples of Key Infections – Ebola Virus Disease Incubation period • 2-21 days. Period of communicability • During acute illness • Infectiousness of body fluids (e.g. viral load) increases as patient becomes more ill • Remains from deceased infected persons are highly infectious • There is no carrier state. Public health management 31 • No effective treatment is available. • Severe cases require intensive supportive care. • There is no vaccine against ebola haemorrhagic fever. • Strict isolation of cases and strict barrier nursing techniques implemented. Communicable Disease Control 32 Communicable Disease Control Sourcehttp://www.abc.net.au/news/201410-09/how-infectious-is-ebola/5802524 Outbreaks of Ebola – How do they start? • Most outbreaks in remote areas • Initially diagnosed as a different febrile illness e.g. Malaria, Typhoid etc. • Patient cared for by relatives before they get to hospital or throughout entire illness (if they live in a remote area) so relatives become infected • Health care workers become infected because disease not recognised and precautions not implemented • Grieving and burial processes of infected individual e.g. holding and washing 33 Communicable Disease Control Outbreaks of Ebola – Current Outbreak • Began in Guinea in 2013 and spread mainly to Liberia and Sierra Leone • Largest outbreak on record • First outbreak to affect an urban area • Overwhelmed existing over-stretched health services • Index case believed to be a child who died in a village in Guinea. Family members developed similar symptoms and subsequently died. As no cases had ever been reported in West Africa, these cases were diagnosed with other diseases more common to the area, therefore it took several months before it was recognised as Ebola. 34 Communicable Disease Control 35 Communicable Disease Control Communicable Disease Control 36 Communicable diseases