Overseas infectious diseases of priority concern

High-risk exotic diseases, potentially harmful to New Zealand’s health, are those which spread easily, New Zealand people are particularly vulnerable to (eg, non-immune), and can cause severe illness.

Exotic diseases overseas can be spread to New Zealand by New Zealand travellers, visitors, and immigrants. International air travel can spread diseases very quickly across borders. Monitoring high-risk exotic diseases overseas is important because it can inform about the possible exposures of New Zealand travellers, visitors, and immigrants to diseases, and help target our disease prevention and control work.

Public Health Emergencies of International Concern

The World Health Organization (WHO) can declare Public Health Emergencies of International Concern (PHEICs) when public health events arise that have international reach and may require an internationally coordinated response (WHO 2019). As at the end of 2023 there were two active PHEICs, COVID-19 and Polio. After a global outbreak, Mpox was declared a PHEIC in July 2022. While this status was lifted in May 2023, cases remained high in some African countries and a surge of cases in mid-2024 led the WHO to declare Mpox as a PHEIC once again in August.

COVID-19 has remained a PHEIC from 2020-2023

Coronavirus Disease 2019 (COVID-19) is the respiratory illness responsible for the COVID-19 pandemic. The disease first emerged in Wuhan, China (PRC) in late 2019 and quickly spread to most countries and territories. The most common symptoms are fever, dry cough, and fatigue. About 80% of people who develop symptoms will recover without needing hospital treatment. The COVID-19 virus continues to evolve and develop new subvariants, and remains a global concern. Cases increased from 80.3 million in 2020 to 424.0 million in 2022, before decreasing to 69.3 million in 2023. The number of deaths peaked earlier, at 3.5 million in 2021, compared to 320,251 deaths in 2023. 

Polio remained a PHEIC in 2023

Poliomyelitis (polio) is a viral disease that can cause severe neurological disability and sometimes death. In addition to wild cirus, circulating weakened polio virus from oral polio vaccine (cVDPV) may cause polio in places where vaccination coverage is low (Venkatesan 2022). An injectable inactivated polio vaccine has replaced the oral polio vaccine in many countries including New Zealand. From 2018–2023, four countries recorded cases of wild poliovirus with all other cases being cVDPV. 

Mpox cases were confirmed in 72 countries in 2023

Mpox (renamed from monkeypox by WHO in late 2022) is a viral disease transmitted by contact with skin lesions, body fluids and respiratory droplets. Despite being endemic in Western and Central Africa since 1970, mpox was a low priority disease until 2022 when an increase in global cases resulted in WHO classifying it as a PHEIC in July of that year. While this status was lifted in May 2023, cases remained high in some African countries, particularly the Democratic Republic of the Congo. A surge of cases in mid-2024 led the WHO to declare Mpox as a PHEIC once again in August 2024.

Measles cases increased between 2021 and 2022, and vaccination rates remained low

Measles cases increased between 2021 (15.5 cases per million people) and 2022 (25.5 cases per million people), and vaccination rates remained lower than optimal.

Non-seasonal influenza was reported in 11 countries in 2023

As well as COVID-19, several other highly infectious respiratory diseases have persisted across the globe in recent years. These include non-seasonal influenzas and Middle Eastern Respiratory Syndrome (MERS). Non-seasonal influenzas are defined as any novel influenza strain that may have pandemic potential. These include avian influenzas, such as H5N1, H3N8 and H10N3, and swine influenzas, such as H1N2 and H3N2.

In 2023, human cases of avian and swine influenzas were identified in eleven countries across four regions. All events were contained with sources identified and spread limited to one or two known human cases. This is an increase over the six countries with cases in 2022.