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Epidemics

by Geoff Rice

Nine thousand New Zealanders died in the 1918 influenza pandemic. Since the advent of vaccination, antibiotics and better sanitation, epidemics have been more readily controlled. However, the COVID-19 coronavirus outbreak which began in 2020 showed that the danger of widespread loss of life from epidemics was far from over.


Epidemics, pandemics and disease control

An epidemic occurs when there is an abnormally high level of a disease in a country at a particular time. The term usually refers to infectious diseases, but it is also possible to have epidemics of non-infectious diseases such as heart disease and diabetes, and conditions such as obesity.

A pandemic occurs when an epidemic becomes prevalent around the world. New Zealand has experienced four pandemics, in 1890–94, 1918, 2009 and since 2020.

An endemic disease is continually present in a population at a low rate, or with a low death rate. An example of this in New Zealand in the 21st century is hepatitis B.

Measuring epidemics

The severity of an epidemic is usually measured by its mortality rate (the proportion of the population who die from the disease). Epidemics of some diseases will have a high morbidity rate – make a lot of people ill – but not cause many deaths. They will cause considerable social and economic disruption if large numbers of people have to stay at home.

Another measure of the severity of an epidemic is the case–fatality proportion, the percentage of people with the disease who die from it. An epidemic may affect a very small proportion of the population yet prove dangerous to those who catch the disease. Most pass unnoticed by the general public, unless increased hospital admissions or an alarming number of deaths are reported.

Red years

Rubella (German measles) was not a notifiable disease (one which had to be reported to public health authorities) and caused very few deaths, but it did cause foetal abnormalities, including deafness. Unusually large numbers of deaf children were born in New Zealand in 1899, 1939 and 1941–42, which suggests that rubella was prevalent during or just before those years.

The severity of an epidemic depends on factors such as the size and health of the population, the nature of the infectious organism, the speed and ease of travel, and the availability of medical services and effective treatments. These factors vary from place to place, and have changed considerably since the early 19th century.

Epidemiology and disease control

Epidemiology is the branch of health science that studies the patterns of diseases, including epidemics. Research into diseases since the 19th century has led to some that were feared killers in the past – for example, influenza and smallpox – being controlled or eliminated by immunisation with a vaccine. However, New Zealand’s immunisation rates are lower than those of many other developed countries.

Some diseases that caused high mortality in the 19th century, such as cholera, scarlet fever and typhoid, have virtually disappeared from developed countries (including New Zealand) due to improvements in personal hygiene, public sanitation, nutrition and health services. However, when developed infrastructures collapse during wars or following natural disasters, these diseases can sometimes reappear and cause epidemics.

Historical epidemic patterns

The historical pattern of epidemics in New Zealand reflects the country’s isolation and relatively small population. The long sea voyage to New Zealand in the 19th century meant that most infectious diseases carried on board had died out by the time the ship arrived.

Some migrant ships suffered high infant mortality from scarlet fever and gastrointestinal infections. Quarantine regulations from the 1870s were aimed at preventing the arrival of unwelcome infections, especially smallpox. In 1872 a smallpox outbreak in Auckland was traced to the SS Nebraska.

Until the 1920s some diseases, such as measles and rubella, disappeared after each local outbreak until they were reintroduced (usually from Australia), because the population was too small and thinly spread to sustain them. Other diseases thrived in New Zealand’s small urban centres. In 1875, typhoid was widespread in towns and cities – there were 323 deaths.

Deaths from infectious diseases have generally declined since records began in the late 19th century. In the 1870s, infectious diseases accounted for one-third of all deaths. By 1900 the proportion was down to 15%, and in 2000 infectious diseases caused less than 7% of all deaths.


The typhoid era, 1810s to 1890s

New diseases

European settlers brought new diseases to New Zealand in the early 19th century. Māori had little or no natural immunity to these diseases, so suffered heavy mortality, particularly from measles and influenza.

Early outbreaks

Early influenza outbreaks among Māori were reported at Foveaux Strait in Southland between 1817 and 1820, and in the Bay of Islands and Mercury Bay in Coromandel in 1838 and 1839. In 1835, measles was reported among Māori working at South Island whaling stations. According to missionary T. A. Pybus: ‘The death rate was serious, and in many cases the people died as they stood. Even in later years skeletons [were] found far from their kaikas (settlements) … lying one across another indicating the suddenness of the end.’1

Unhealthy settlements

Early European settlements were often extremely unhealthy, lacking clean water supplies and effective sewage disposal. These conditions assisted the spread of infectious diseases. Typhoid and other bacterial infections were common, along with diphtheria, measles, whooping cough (pertussis), scarlet fever and tuberculosis. Infant mortality rates were high and medical treatments were often ineffective.

Respiratory infections caused many deaths, mostly attributed to bronchitis or pneumonia. Tuberculosis was a constant killer – an endemic epidemic – from this period until the 1950s.

Evidence of epidemics

Evidence for epidemics in New Zealand is imprecise before 1872 because statistics on causes of death were not collected. Even after 1872, misdiagnosis and under-reporting were common. Doctors in the 19th century could not easily distinguish diseases with similar symptoms such as diphtheria, scarlet fever and measles. The cause of an infant death might be entered in official records as diarrhoea or ‘want of breast milk’, when typhoid was the real cause.

Typhoid troubles

Typhoid can usually be treated with antibiotics and rehydration. Untreated case-fatality rates usually vary between 10% and 30%, but can exceed 40%. Untreated typhoid typically follows three distinct stages, each lasting about a week. In the first week, the body temperature rises slowly, and fever fluctuations are seen alongside a headache and cough. High fever, with delirium and agitation, is typical of the second week, along with diarrhoea resembling green-pea soup. In the third week, dehydration and pneumonic complications may accompany the fever. Septicaemia, peritonitis and intestinal perforation are potentially fatal complications.

Typhoid

Typhoid was one of the most common diseases of 19th-century New Zealand. It is transmitted by water, milk or food contaminated by the faeces of an infected person. It is caused by the bacterium Salmonella enterica typhi, which produces symptoms of high fever, sweating, diarrhoea, headache and cough.

Typhoid was most prevalent in fast-growing towns and on the goldfields, where cesspits often leaked into water supplies. Infants and young children were especially vulnerable. Registered typhoid deaths in New Zealand peaked at 323 in 1875.

Typhoid death rates declined in towns and cities as sanitation improved, but remained high in rural and Māori districts well into the 20th century.

In the 19th century, Christchurch was one of the few places with a Board of Health and an active medical officer of health. Dr Courtney Nedwill persuaded the city council to abolish cesspits and switch to a system of pans and ‘night-soil’ collection. This immediately reduced the death-rate from infectious diseases, even before the city completed New Zealand’s first underground sewerage system in 1882.

In 1881, Dr Nedwill investigated a typhoid outbreak in Christchurch and at Sunnyside Asylum, tracing its source to a dairy farm in Lincoln Road. This led to an amendment to the Health Act that enabled the inspection of dairy farms by health officers. Despite this provision, milk-borne typhoid infections continued to cause epidemics in Auckland and other North Island towns until the 1940s.

Footnotes

The influenza era, 1890s to 1920s

The period 1890s–1920s was dominated by two influenza pandemics (1890–94 and 1918), with annual epidemics in between.

Plague made its first and only New Zealand appearance in 1900, but it caused only a handful of deaths and disappeared after 1911. There were outbreaks of measles and whooping cough (pertussis) in 1907, and diphtheria in 1917.

Improvements in disease identification

With the advent of bacteriology (the study of bacteria in relation to disease) in the late 19th century, identification of many diseases became more precise. New Zealand’s adoption of the Bertillon index (a list of known diseases) in 1909 reflected this.

However, statistics remained unreliable in this era, especially because Māori deaths did not have to be registered with the government until the early 20th century, and even in 1918 hundreds of Māori deaths from influenza were not registered. Statistics for Māori births, deaths and marriages remained incomplete until the 1940s.

Laboratory techniques for identifying diseases and their effects on the human body have since been vastly improved, which makes modern statistics for epidemics more reliable.

1913 Northland smallpox epidemic

Smallpox, a highly infectious viral disease, was a major killer worldwide before the discovery of effective vaccination in the late 18th century. Mass immunisation campaigns in the 19th and 20th centuries eventually eradicated smallpox – it now exists only in laboratores.

Small pox, big effect 

Smallpox was at first hard to distinguish from chickenpox, but it was much more dangerous. As the disease developed, two types of case could be fatal: when the spots bled and became septic, or if the rash extended into the air-passages, blocking the windpipe. Many survivors were forever marked by scars.

The most significant outbreak occurred in 1913 in Northland. It was traced to a Mormon missionary who had caught smallpox on a ship sailing to New Zealand from Canada. After he attended a hui in Northland in April 1913, the disease spread rapidly. Most of the two thousand reported cases were Māori, as were all of the 55 people who died.

A mass vaccination programme was set up and travel restrictions were imposed to slow the spread of infection. Newspapers made much of the outbreak, blaming the epidemic on lack of sanitation and poor living conditions among Māori – yet Māori were more willing to receive vaccinations than many Pākehā.

The epidemic was declared over by December 1913, although the last case was not notified until April 1914.

1918 influenza pandemic

New Zealand’s worst disease disaster to date is the influenza pandemic of November 1918, which killed more than 50 million people worldwide, and 9,000 in New Zealand. No other recorded influenza pandemic has been so deadly – and nobody knows why it was so lethal.

It occurred in the wake of the First World War, when the movement of large numbers of troops by sea and rail greatly facilitated the spread of infection. Troops returning to New Zealand brought the virus from Europe. It reached epidemic proportions in late October, peaked in late November and was nearly over by early December.

Many people believed that the killer virus was brought to New Zealand by the passenger ship Niagara, which docked in Auckland on 12 October 1918 full of influenza sufferers. Prime Minister William Massey and Finance Minister Sir Joseph Ward were on board. Critics later argued that they arranged for the ship to avoid quarantine, but this was not the case, and the Niagara was later conclusively ruled out as the source of infection.

Perils of being the breadwinner 

It has been suggested that far more men than women died during the 1918 influenza pandemic because men were typically the family breadwinners, so had to go to work instead of staying home when sick. Dairy farmers were at greater risk of collapsing or relapsing than more sedentary professions, because they had to milk their cows twice every day.

Symptoms exhibited by sufferers included chills, fever, runny nose, sore throat, coughs, headache and muscular pain. The real killer in 1918 was pneumonia – a secondary infection. The skin of some people who caught pneumonia darkened because of burst blood vessels. If the whole body became virtually black, death was often imminent. Later in life, sufferer Grace Stewart described her experience: ‘I was in bed for six weeks. My fingers and fingernails went black. My tongue was covered with some sort of fungus half an inch thick … The pain in the whole of my body was terrible.’1

Unlike in other countries, where male and female deaths were about equal, New Zealand death rates for males were double those for females in the worst-affected age groups. The Māori death rate was more than eight times that for Pākehā. The highest regional death rates for Pākehā were in Southland, King Country, Wellington and Auckland. Auckland city had the largest Pākehā death toll at 1,128 (7.6 per 1,000). The national figure was about 5.5 per 1,000. Nationwide, 135 Pākehā children lost both parents and 6,415 lost one.

Footnotes
    • Quoted in Geoffrey W. Rice, Black November: the 1918 influenza pandemic in New Zealand. 2nd edition. Christchurch: Canterbury University Press, 2005, p. 86. Back

The polio era, 1920s to 1960s

Improved sanitation and water supplies virtually eliminated the major bacterial diseases of the 19th century from New Zealand’s European population by the 1920s. Non-communicable diseases such as cancer and heart disease replaced epidemic diseases as the leading causes of death.

Ancient disease

Polio is probably a very old disease – a 3,500-year-old Egyptian wall carving shows a man with the characteristic withered leg of a polio victim.

Poliomyelitis

Apart from isolated outbreaks of diphtheria and typhoid, and continued high death rates from tuberculosis, the most alarming infectious disease of this era was poliomyelitis (polio), an acute viral disease affecting the spinal cord and nervous system. Symptoms include fever, headache, malaise, pain and stiffness in back and neck, and partial or complete paralysis of limbs or the entire body. Case-fatality rates from paralytic polio have varied between 2% and 10%. New Zealand experienced polio epidemics in 1916, 1925, 1927, 1937, 1948–49, 1952–53 and 1955–56.

Polio is typically a disease of children and adolescents, but the risk of paralysis increases markedly with the age of the patient, making young adults especially at risk if they catch the disease. In early outbreaks there was no effective treatment, so careful nursing and palliative care (which alleviates symptoms rather than the cause) were the main medical responses. The lives of seriously paralysed patients could only be saved by long periods in a compression chamber or ‘iron lung’. Survivors with a withered leg were fitted with strengthening callipers, which helped them walk. Public health campaigns in the 1950s stressed personal hygiene – schools provided buckets of disinfectant in their toilet blocks.

Immunisation

Effective polio vaccines were developed in the 1950s. Jonas Salk’s inactivated vaccine of 1955 was followed by Albert Sabin’s weakened live virus oral vaccine in 1960. In New Zealand, use of the Salk vaccine delayed the reappearance of polio between 1956 and 1961. After this a mass immunisation campaign using the Sabin oral vaccine achieved high population coverage and eliminated the polio virus from New Zealand.


New epidemics, 1970s to early 21st century

Despite improved health services and access to vaccines and antibiotics, New Zealand continued to experience severe outbreaks of disease in the late 20th and early 21st centuries.

Influenza

Deaths linked to influenza (the flu) and associated pneumonia have declined since the 1970s, when the virus caused, on average, about 1,000 deaths every year.

An annual influenza vaccine is offered in New Zealand to provide protection from the virus. It is adjusted each year to cover the strain or strains of the virus circulating at the time. Despite improved uptake of the vaccine, seasonal influenza epidemics continue to have an impact, especially on older people. Between 2000 and 2021, an average of 557 people died from influenza or pneumonia each year. Of these, 68% were aged 85 or older.

The 2009 influenza A (H1N1 – known as swine flu) pandemic generated more than 3,000 cases and caused 20 deaths in New Zealand, far fewer than health officials had feared.

Meningococcal disease

An outbreak of meningococcal group A in Auckland in 1985–86 was controlled by mass immunisation. Meningococcal disease reached epidemic proportions in the 1990s and early 2000s.

A new group B epidemic started in 1991, when 78 cases were recorded, compared to an average of 51 per year (1.5 cases per 100,000 people) previously. A New Zealand-only strain of the disease soon caused a major outbreak.

The highest infection rates were among Māori and Pacific Island children aged under five. The upper North Island, particularly Northland, Auckland and Rotorua, was most affected. The epidemic peaked in 2001 with 650 cases (17.4 per 100,000 people); 252 deaths were attributed to meningococcal disease between 1991 and 2007.

Brain fever

Meningococcal disease is a bacterial disease. It causes meningitis (an inflammation of the protective membranes covering the brain and spinal cord) and septicaemia (blood poisoning). Severe infections can cause shock, coma and death within a few hours if not treated quickly with antibiotics. Meningococcal disease can have serious long-term effects on survivors, including deafness and epilepsy.

A new vaccine developed specifically for the New Zealand strain of meningococcal group B was introduced in 2004. More than 1.1 million children and young adults were immunised. This was one of New Zealand’s largest mass-immunisation campaigns and involved schools, primary health care providers and district health boards. It cost more than $200 million. Reported cases declined from 342 in 2004 to 105 (1.7 per 100,000 people) in 2007, by which time the epidemic was regarded as controlled.

In March 2023 the meningococcal group B vaccine was added to the national immunisation schedule for the first time, which made it free for all children under five, and for teenagers and young adults living in crowded situations such as university hostels. A catch-up programme was organised to vaccinate children who had missed out previously.

Measles

Although a measles vaccine was made available in 1969, low immunisation rates meant that New Zealand continued to experience regular outbreaks of the disease. Improved uptake of the vaccine after 1980 reduced the frequency of outbreaks but had little effect on total case numbers when an outbreak did occur.

New Zealand experienced two large measles epidemics in the 1990s. The first, in 1991, resulted in 10,000 reported cases, an additional 30,000 suspected cases, several hundred hospitalisations and seven deaths. In response to this epidemic, a second dose of the measles, mumps and rubella (MMR) vaccine was added to the immunisation schedule.

A second, smaller, epidemic in 1997 resulted in 2,169 cases, but no deaths. This epidemic had been predicted, and a mass immunisation campaign planned to prevent it. When the epidemic began three months before the scheduled start of the campaign, this was brought forward and helped to limit the spread of the disease.

Although New Zealand has continued to experience measles outbreaks, the World Health Organization (WHO) declared the country free of endemic (circulating constantly in the population) measles in 2017. Outbreaks still occur when measles arrives from overseas. The last major outbreak was in 2019–20, when 2,194 New Zealanders caught the disease.

COVID-19

COVID-19, a new strain of coronavirus named SARS-CoV-2, spread around the world in early 2020. The virus, which primarily affects the respiratory system, soon overwhelmed health systems worldwide, leading to large-scale loss of life. In a ‘last-resort’ measure, the WHO declared the outbreak a ‘public health emergency of international concern’ on 30 January 2020.

New Zealand reported its first case of COVID-19 in late February 2020. As the number of local cases grew, the government introduced various public health measures to control the spread of the virus, many of them unprecedented in New Zealand history.

The most significant was a nationwide stay-at-home order (‘lockdown’). All New Zealanders were told to limit their physical contact with others and to only leave their homes for ‘essential’ activities such as exercising, grocery shopping and medical appointments. Mass testing of those with symptoms, contact tracing of infected persons and mandatory quarantine for people entering the country were also introduced to combat the spread of the virus. Wearing face masks was strongly encouraged, and later made compulsory in some environments.

Variants of concern: From Alpha to Omicron

The SARS-CoV-2 virus was first identified in China and probably originated in animals. Over time genetic mutations produced new versions of the virus, some of which posed a greater risk to public health than others. The WHO called them variants of concern and used the Greek alphabet to give them names that were easy to say and remember. Starting with the Alpha variant, which emerged in Britain in late 2020, COVID-19 worked its way through the alphabet, with Delta and Omicron the dominant variants in New Zealand in late 2023.

The lockdown was highly effective in reducing transmission of the virus, and by June 2020 there were no active cases of COVID-19 in the community. Most restrictions on movement and activities were lifted until August, when a new outbreak occurred. As the virus evolved and developed new variants, further outbreaks resulted, leading to more lockdowns. The severity of each lockdown varied, depending on the location and the number of cases.

A vaccine first became available in February 2021, and immunisation eventually became the primary means of fighting the virus. Proof of vaccination was required to enter some public settings, and health and education sector workers were required to be vaccinated to keep their jobs. The vaccine roll-out was the largest and most expensive mass immunisation campaign in the country’s history, costing $1.4 billion. By December 2021, 90% of the population aged 12 and over had received two doses of the vaccine.

Some objected to aspects of the government’s response, especially to the closing of international borders, which made it difficult for New Zealanders to return from overseas, and to the introduction of vaccination requirements for some professions. Despite this, the community was largely co-operative with the rules put in place.

Māori were very aware of the impact the 1918 influenza epidemic had had on their communities. Iwi and hapū, marae and Māori health organisations played important roles in communicating information, hosted testing and vaccination events, and provided families in need with food parcels during lockdown. To limit the spread of the disease, some set up roadblocks to stop people entering isolated communities.

As the country shifted to living with the virus, COVID-19 protective measures gradually ended. By the time the last public health requirements were lifted in September 2022, New Zealand had recorded more than 1.7 million cases of COVID-19, and more than 2,000 deaths (0.04% of the population). At the global level, there had been more than 612 million confirmed cases and more than 6.5 million deaths (0.08%). New Zealand was one of the few countries to record fewer total deaths than expected over the first two years of the pandemic, thanks to lockdowns curtailing the spread of infections such as seasonal influenza.

The virus has become a major cause of hospitalisation and a leading cause of death, especially amongst older people, accounting for 6.3% of all deaths in 2022. Since the start of the pandemic, those aged 20 to 49 have made up almost 50% of cases, while 94% of those who have died have been aged 60 or older.


Preventing epidemics, 1970s to early 21st century

Immunisation (vaccination)

Immunisation (vaccination) is one of the best ways to limit the spread of disease. Prior to 1960 only a few vaccines were available in New Zealand. People were often vaccinated in response to a disease outbreak or as part of specific immunisation programmes. Doctors were authorised to decide the age at which a child should be immunised.

In 1960, the Health Department introduced a national immunisation schedule which recommended vaccination against certain diseases at specific ages. Initially only the combined diphtheria-tetanus-pertussis (DTP) vaccine was offered. The schedule later expanded to include many other vaccines, which are given free of charge starting at six weeks of age.

Since the introduction of the schedule, immunisation has successfully controlled diseases such as hib disease (haemophilus influenzae type B, which can cause meningitis and epiglottitis), which has been virtually eradicated. Other vaccines on the schedule, such as the HPV vaccine, have the potential to be equally effective.

How immunisation works

People are immunised against infectious diseases with vaccines, which contain either fragments of a disease germ or weakened germs. These prompt the body to produce cells and antibodies that protect the person from the disease. Vaccinations have been widely used since the 19th century. To prevent some diseases, such as measles, from circulating in the community, at least 95% of the population needs to be vaccinated. Te Whatu Ora Health New Zealand’s national immunisation target is 95% of two-year-olds fully immunised – in 2023, 83.1% were fully immunised.

In 2008, the Ministry of Health introduced a programme that made vaccination against the highly infectious HPV (human papillomavirus) available to young women born in 1990 and 1991. From 2017 the vaccine was free for every female aged 9 to 26. It was delivered primarily through schools. The aim was to protect young people from the sexually transmitted HPV virus before they became sexually active. HPV has been linked to cancers of the cervix, mouth and tongue, and other invasive cancers. Vaccination is extremely effective, and full implementation of the programme would save many lives. New Zealand has yet to reach its target of 75% of the population fully immunised.

Legislation and regulation

In epidemic or pandemic situations, the Health Act 1956 and regulations issued under it give local medical officers of health special powers. They may quarantine or disinfect people, vehicles or animals, restrict the movement of people into or out of an area, close premises such as schools, and commandeer resources needed to fight the disease. In very serious situations, a state of emergency can be declared, giving the authorities additional powers to control behaviour.

Because the public health response to the outbreak of COVID-19 in New Zealand was so complex, special legislation was required. The COVID-19 Public Health Response Act 2020 gave the Minister of Health numerous powers, including the ability to order people to self-isolate, to wear masks and to restrict their movements, even if they were not infected with the disease. In addition, a national state of emergency was declared in March 2020, the first time one had been imposed for a pandemic.

Updating regulatory standards can also help to control the spread of disease. A campylobacteriosis (a gastrointestinal disease mainly caused by eating chicken that has not been properly cooked) epidemic peaked in 2006 and then abated, probably due to new regulatory standards in the poultry industry.

Monitoring

Because of the ongoing risk of epidemics, health practitioners and medical laboratories are legally required to notify the local medical officer of health if they suspect or confirm a case of certain diseases, including measles, tuberculosis and many respiratory diseases. Since 2016 it has been possible for doctors to report a few of these diseases, including AIDS and HIV, without providing the name of the patient.

The Institute of Environmental Science and Research, a Crown research institute, monitors infectious diseases and provides information to the Ministry of Health on disease rates and distribution, identifies outbreaks, monitors interventions and predicts emerging disease hazards.

The Ministry of Health monitors infectious diseases and oversees programmes delivered by Te Whatu Ora Health New Zealand to contain them and minimise their effects. In an international context, the ministry works closely with the World Health Organization (WHO), providing the United Nations agency with New Zealand health statistics and other information.

International responsibilities

New Zealand committed itself to playing a role in international work to combat the spread of diseases by signing up to the International Health Regulations (IHR) 2005. The IHR are an agreement developed by WHO member countries to combat the spread of disease and other public health hazards. Member countries have a responsibility to develop measures to prevent, prepare for and respond to public health events, while avoiding disruption to international travel and trade. They are also required to inform the WHO of any public health event that risks spreading across borders. In 2022, member countries agreed to amend the IHR to incorporate lessons learned from the COVID-19 pandemic. Ashley Bloomfield, New Zealand’s former director-general of health, was selected as a co-chair of the working group to amend the regulations.

During the COVID-19 pandemic, New Zealand purchased and donated millions of doses of vaccine to countries in the Pacific and elsewhere that could not afford to buy them.

Barriers to disease control

Though epidemics have become less frequent, studies have found that hospital admission and discharge rates for infectious diseases have been increasing since the 1980s, if not earlier. This counters the prevailing understanding that these diseases have become less of a burden. As international air travel became increasingly affordable, New Zealand was no longer isolated from the spread of diseases such as HIV/AIDS, SARS (seasonal acute respiratory syndrome), influenza and COVID-19.

Falling global and national childhood vaccination rates in recent years mean New Zealand is at risk of outbreaks of serious diseases. A combination of misinformation and an emphasis on COVID-19 vaccination and protective health measures has seen less time and effort put into preventing the spread of other serious illnesses such as measles. In addition, poor recordkeeping about childhood immunisation, especially in the 1990s and early 2000s, has made it difficult for children born in those years to find out if they are immunised against certain diseases.

Climate change may increase the likelihood of some tropical diseases reaching New Zealand. Diseases such as dengue fever, Zika virus and Ross River virus are not currently present in New Zealand’s mosquito population. Rising temperatures and increased rainfall may allow disease-carrying species of mosquito to establish populations here, leading to local outbreaks.


External links and sources

More suggestions and sources


How to cite this page: Geoff Rice, 'Epidemics', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/epidemics/print (accessed 16 April 2024)

Story by Geoff Rice, published 5 May 2011, reviewed & revised 8 February 2024