Notifiable Diseases

Infectious disease notification is important to enable prompt investigation, risk assessment and response to cases of disease and contamination that present, or could present, a significant risk to human health.

This module covers the chain of infection, illustrating how infectious diseases are commonly transmitted, followed by possible modes of transmission. The implications for public health, legalities and speed of notification are then discussed.

Context

The statutory notification of infectious diseases has been a crucial health protection measure in the United Kingdom (U.K.) since the late 19th century. The purpose of notification is to enable the prompt investigation, risk assessment and response to cases of infectious disease and contamination (such as with chemicals or radiation) that present, or could present, a significant risk to human health¹. This module explains the guidance on notification requirements of registered medical practitioners (RMPs).

RMPs have a statutory duty to notify the proper officer at their local health protection team (HPT) of suspected cases of certain infectious diseases under the Health Protection (Notification) Regulations 2010. The list of which can be found on the government website. Emergency Departments (EDs) are an important reporting source for notifiable diseases, so it is vital to improve awareness on reporting responsibilities among Emergency Medicine (EM) clinicians and make the reporting process clear. This module aims to put the notification process in context of the wider public health implications and hopes to improve awareness and reporting practices among EM clinicians.

Table 1 Diseases notifiable to local authority proper officers under the Health Protection Regulations 2010

Report other diseases that may present significant risk to human health under the category ‘other significant disease’ examples of these are:

1. Chemical exposure e.g. Carbon monoxide, lead, mercury
2. Radiation exposure
3. New and emerging infections (e.g. new strains of influenza)
4. Cases that occur as part of an outbreak/ cluster e.g. (clostridium difficile, norovirus)
5. Other infections where vulnerable contacts are at risk: e.g. infection in a healthcare worker, varicella zoster exposure in pregnant or immunocompromised persons

Learning bite

This list is not exhaustive. If in doubt, please telephone your local HPT.

First, let us recap how infectious diseases are transmitted. Transmission usually occurs when an infectious agent is transmitted from an infected individual to a susceptible person. The traditional epidemiologic triad model holds that infectious diseases result from the interaction of agent, host, and environment. More specifically, transmission occurs when the agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission, and enters through an appropriate portal of entry to infect a susceptible host. This sequence is called the chain of infection (see Figure 1 for further illustration)².

Figure 1 The chain of infection is a set of 6 intertwined links that allow for communicable diseases to spread³.

There are different classifications for modes of transmission. One such classification (taken from the CDC website²) is illustrated here:

• Direct
  • Direct contact
  • Droplet spread
• Indirect
  • Airborne
  • Vehicleborne
  • Vectorborne (mechanical or biologic)

Direct contact occurs through skin-to-skin contact, kissing, and sexual intercourse. Direct contact also refers to contact with soil or vegetation harbouring infectious organisms. Thus, infectious mononucleosis (“kissing disease”) and gonorrhoea are spread from person to person by direct contact. Hookworm is spread by direct contact with contaminated soil.

Droplet spread refers to spray with relatively large, short-range aerosols produced by sneezing, coughing, or even talking. Droplet spread is classified as direct because transmission is by direct spray over a few feet, before the droplets fall to the ground.

Indirect transmission refers to the transfer of an infectious agent from a reservoir to a host by suspended air particles, inanimate objects (vehicles), or animate intermediaries (vectors).

Airborne transmission occurs when infectious agents are carried by dust or droplet nuclei suspended in air. Airborne dust includes material that has settled on surfaces and become resuspended by air currents as well as infectious particles blown from the soil by the wind. Droplet nuclei are dried residue of less than 5 microns in size. In contrast to droplets that fall to the ground within a few feet, droplet nuclei may remain suspended in the air for long periods of time and may be blown over great distances.

Vehicles that may indirectly transmit an infectious agent include food, water, biologic products (blood), and fomites (inanimate objects such as handkerchiefs, bedding, or surgical scalpels).

Vectors such as mosquitoes, fleas, and ticks may carry an infectious agent through purely mechanical means or may support growth or changes in the agent.

Learning Bite

Think why this PERSON, from this PLACE, has developed these SYMPTOMS at this TIME. Always check for localising signs, exposures, immunosuppression and drug history.

Knowledge of the portals of exit and entry and modes of transmission provides a basis for determining appropriate control measures. In general, control measures are usually directed against the segment in the infection chain that is most susceptible to intervention, unless practical issues dictate otherwise.

Interventions are directed at:

• Controlling or eliminating agent at source of transmission by diagnosing and treating infected individuals as early as possible

• Protecting portals of entry (preventing the transmission of infection) through isolation, quarantine, personal hygiene, disinfection, use of condoms or use of personal protective equipment like masks. This has achieved a high level of importance during the Covid-19 pandemic

• Increasing host’s defences and reducing the number of susceptible individuals through immunisation or chemoprophylaxis where possible

Health education also performs an important role in disease prevention and control.

Doctors caring for individuals suspected of having certain infectious diseases have a legal obligation to notify the details of the case to the proper officer of the local authority. This is usually the Consultant in Communicable Disease Control (CCDC) at the local unit of the Health Protection Agency (HPA).

This enables the officer to put appropriate preventive and control measures into place if necessary.

Notification forms are available on the government website or your hospital’s intranet site. If urgent action is likely to be required, notification to the HPT can be carried out by phone or via email using the postcode lookup link.

Learning Bite

All registered medical practitioners have a statutory duty to notify certain infectious diseases to the local health protection team.

Notification must be timely if public health interventions are to be effective in controlling the further spread of infection or contamination. Notification has the secondary benefit of providing data for use in the epidemiological surveillance of infection and contamination. These data can help, for example, in monitoring the effect of existing interventions (e.g. immunisation), identifying the need for new interventions (e.g. outreach services for specific groups) and informing the planning of healthcare services.

Complete the notification form to inform your local health protection team immediately about suspected notifiable disease cases.

Do not wait for laboratory confirmation of the suspected infection or contamination before notification. Send the certificate to the proper officer within 3 days, or phone them within 24 hours, if the case is urgent.

Speed of notification is particularly essential for diseases such as meningococcal infection, food poisoning, and hepatitis where contact tracing is required to limit the spread.

Learning bite

The reporting of notifiable diseases can be improved by ensuring that all medical practitioners:

• Are aware of their legal obligations
• Understand the rationale and the purpose of notification
• Ensure that infectious diseases from hospitals and general practice are reported to the proper authorities at the earliest opportunity

TIP: Notification forms should be prominently displayed in ED or on the hospitals Intranet to encourage notification, you can also download and customise this poster to be displayed in your ED.

Details of notified diseases collected locally are submitted regularly in an aggregated form to the HPA Centre for Infections, London.

Data collected in this way can be used to monitor local disease occurrence and explore local and national trends in infectious diseases.

Notification data complement laboratory reporting systems and provide information on some diseases which are often not diagnosed in laboratories, e.g. whooping cough.

Surveillance is:           

• Systematic collection of information
• Collation
• Analysis of data
• Dissemination of results

Surveillance can:       

• Describe patterns of disease
• Identify risk factors
• Indicate a change in epidemiology

Learning bite

Good surveillance is vital and can enable early detection of outbreaks of diseases such as food poisoning or epidemics of influenza. Good surveillance can evaluate the effectiveness of prevention and control programmes and set priorities for resource allocation.

• Notification of infectious diseases is a legal requirement in the UK
• Reporting notifiable diseases to the CCDC at the local health protection unit enables prompt action, i.e. preventive and control measures
• Data collected can be used to monitor local disease occurrence and explore local and national trends in infectious diseases. This is called surveillance
• Comparing notifications of disease with data obtained from other sources can give indications of a change in the epidemiology of the disease and the effectiveness of interventions
• Good surveillance depends on completeness of notification of infectious diseases. This can be improved by ensuring that junior doctors are aware of their legal obligations, the rationale and the purpose of notification, and that infectious diseases are reported to the proper authorities

Pitfalls

• Forgetting the wider public health implications when assessing a patient; always take a full social history.
• Not taking a detailed travel, exposures, immunosupression and drug history in any patient presenting with a fever or history of fever.
• For those patients returning from the tropics with history of fever – don’t forget to always send blood cultures, blood borne viral screen and malaria rapid diagnostic test (a positive result needs to be acted upon the same day).
• Waiting for laboratory confirmation of the suspected infection or contamination before sending a notification form to the local HPT.

References

1. Department of Health. Health protection legislation guidance 2010 : Department of Health – Publications [Internet]. [cited 2021 Nov 29].
2. Centers for Disease Control and Prevention. Principles of Epidemiology | Lesson 1 – Section 10 [Internet]. Third Edition. 2011 [cited 2021 Nov 29].
3. Chain of Infection Overview [Internet]. [cited 2021 Nov 29].
4. Ellis J, Hearn P, Johnston V. Assessment of returning travellers with fever. Medicine (Abingdon). 2018 Jan;46(1):2-9.
5. Thwaites GE, Day NP. Approach to Fever in the Returning Traveler. N Engl J Med. 2017 Feb 9;376(6):548-560.

Additional resources

• British Infection Association (BIA), for UK recommendations and guidelines.
• Centres for Disease Control and Prevention (CDC).
• National Travel Health Network and Centre (NaTHNaC)
• ProMED-mail (electronic reporting system for infectious diseases outbreaks).
• Public Health England (PHE, previously HPA)
• WHO outbreak data

Telephone advice

• Imported Fever Service, HPE, UK: +44 (0) 844 778 8990 Contact after discussion with local microbiology, virology or infectious diseases consultant.
• Hospital for Tropical Diseases, UCLH, London, UK Tel: +44 (0) 203 456 7890 and ask for the Tropical/ID physician on-call
• Liverpool School of Tropical Medicine, Liverpool, UK. Tel.: (0900–1700 h) +44 (0) 151 705 3100 Tel.: (24 h) +44 (0) 151 706 2000 and ask for the Tropical/ID physician on-call. Liverpool University Hospitals