New additions to list of notifiable diseases


Following the signing into law of the Infectious Disease (Amendment) Regulations 2018 by Minister Simon Harris on 18th December 2018, a number of additions have been made to the list of notifiable diseases. 

All medical practitioners, including clinical directors of diagnostic laboratories, are required to notify the Medical Officer of Health (MOH)/Director of Public Health (DPH) of certain diseases. This information is used to investigate cases thus preventing spread of infection and further cases. The information will also facilitate the early identification of outbreaks. It is also used to monitor the burden and changing levels of diseases, which can provide the evidence for public health interventions such as immunisation.

Neonatal herpes simplex
Inclusion of neonatal herpes simplex in the list of notifiable diseases will raise awareness and facilitate greater understanding of the burden of this rare but potentially devastating viral infection. Babies can become infected with Herpes Simplex Virus (HSV) in the womb (~5%) around the time of birth through contact with HSV infected sections in the birth canal (~85%) or by contact with the virus in the days after birth (10%). Many factors influence the risk of the baby getting an infection but the risk is greatest when HSV infection is acquired for the first time by the mother in pregnancy and particularly when the infection occurs in the third trimester close to the time of delivery. The virus can also be passed to a newborn baby from caregivers or those in close contact who have HSV skin infections e.g cold sores. Laboratory confirmation is required for confirmed cases of neonatal herpes simplex, although probable cases can be notified based on clinical criteria with three presentations classically described:

  • Infection of the Skin, Eye and/or Mouth (SEM Disease)
  • Infection involving the brain (Central Nervous System (CNS) infection)
  • Infection involving multiple organs such as the lungs, liver, brain (disseminated infection)

Surveillance of herpes simplex (neonatal) will be conducted using the national Computerised Infectious Disease Reporting (CIDR) system. The neonatal herpes simplex case definition and a frequently asked questions page have been added to the HPSC website. 

CPE are also known as carbapenem resistant Enterobacteriaceae (CRE) and invasive infection first became notifiable in Ireland in 2012. The 2018 Infectious Diseases Regulations update the terminology from CRE to CPE and extend the requirement for notification to include new cases of CPE colonisation and non-invasive infection, as well as invasive CPE infection which continues to be notifiable. 

CPE are bacteria that produce one of a family of enzymes with specific activity against carbapenems, known as carbapenemases. The genetic material that enables bacteria to produce a carbapenemase is readily transferred between different species of bacteria and is considered a key factor in the global dissemination of CPE. CPE were first reported in Ireland in 2009, with a rapid increase in detection, particularly since 2016, which resulted in the Minister of Health declaring CPE a public health emergency in Ireland in October 2017. 

The updated case definition and guide to notification of CPE are available on the HPSC website.

mcr-positive Enterobacteriaceae
mcr is an acronym for mobilised colistin resistance. The mcr gene encodes for the production of an enzyme which alters the Gram-negative bacterial cell membrane, so that the antimicrobial colistin cannot damage it, rendering colistin inactive and enabling the bacteria to become resistant to colistin. The mcr gene is carried on a plasmid, which is a mobile genetic element readily transferrable between bacteria. Colistin is categorised by the World Health Organization as a reserve group antimicrobial that should be treated as a last resort option for serious, life-threatening infection due to multi-drug resistant organisms (MDRO), generally accepted as organisms that display resistance to three or more antimicrobial classes. 

In the context of increasing incidence of MDRO and CPE, colistin is an important treatment option. While colistin has been available for over 60 years, it has not been widely used in human medicine. In November 2015, a research group in China published evidence that mcr-1 had been found in human, animal and environmental Enterobacteriaceae isolates in China, generating global concern, because of the potential for transmissibility. Subsequently, mcr has been detected on all continents and a small number of cases have been confirmed in Ireland to-date. The update to the Infectious Diseases Regulations makes confirmation of mcr-positive Enterobacteriaceae notifiable in Ireland, whether it represents invasive or non-invasive infection or colonisation and this will facilitate close monitoring of the epidemiology of this important resistance mechanism. 

The mcr-positive Enterobacteriaceae case definition has been added to the HPSC website. 

Novel or Rare Antimicrobial-resistant Organisms (NRAO)
Beyond the specific issues of CPE and mcr-positive Enterobacteriaceae, there has been increasing concern regarding emergence and spread of other antimicrobial resistant organisms. For example; linezolid-resistant enterococci, multi-drug resistant coagulase negative staphylococci and Acinetobacter spp, along with multi-drug resistant Candida auris

While infection caused by any of the above could potentially be notified under the heading “unusual cluster or changing pattern of illness”, cases (as distinct from outbreaks) of infection with antimicrobial-resistant organisms are rarely if ever notified under this heading. Additionally, the provision does not apply to colonisation or carriage, which differs from infection. As antimicrobial resistance is a rapidly changing field, it may not be practical to change the Infectious Disease Regulations in response to emergence of individual novel or rare antimicrobial resistance patterns in a sufficiently-timely manner. Hence, the introduction of this new category of NRAO.

The novel or rare antimicrobial resistant organism (NRAO) case definition has been added to the HPSC website.

Further resources
List of notifiable diseases
Case definitions for notifiable diseases
Notifying infectious diseases - what, who, how, when