Emerging and re-emerging diseases

• Emerging diseases represent infections that have recently appeared among humans or that are rapidly spreading among humans in terms of incidence or geographical distribution
• They are recognized as pathogens whose incidence have increased within the past two decades or threaten to increase in the near future
• During the last 40 years, at least 50 emerging infectious agents have been identified with approximately 10% of them being bacterial agents
• The term ‘emerging disease’ has a fairly broad definition and in general, encompasses any one of three disease situations:
• a known agent appearing in a new geographic area
• a known agent or its close relative occurring in a hitherto unsusceptible species
• a previously unknown agent detected for the first time
• Re-emerging disease is the reappearance of a known infection after a decline in incidence
• They describe infectious agents that have been known for some time, had fallen to such low levels that they were no longer considered public health problems and are now showing upward trend in incidence or prevalence worldwide
• In December 2015, a group of experts met in Geneva to assess emerging global disease and to group them into categories
• The Most Dangerous diseases were
• Ebola Virus Disease (EVD)
• Marburg
• Severe Acute Respiratory Syndrome (SARS)
• Middle East Respiratory Syndrome (MERS)
• Nipah
• Lassa fever
• Rift Valley Fever (RVF) and
• Crimean Congo Haemorrhagic Fever (CCHF)
• The second category ranked as Serious Diseases includes
• Chikungunya (CHIK)
• Severe Fever with Thrombocytopaenia Syndrome (SFTS) and
• Zika virus
• The Human Immunodeficiency Virus (HIV), Tuberculosis, Malaria, Avian influenza and Dengue, though considered important, were not ranked because they have already received much attention and funding
• And most recently, Corona Virus Disease (COVID-19), emerged in late 2019
• Fifty percent of known human pathogens and nearly 75% of all emerging infectious diseases are zoonotic in origin, many of which spilled over from natural wildlife reservoirs into human populations, either directly or through contact with domestic animals

Agent

• Microbial Adaptation
• Resistance to drugs and pesticides
• Mutation (Antigenic drift and shift)

Host

• Susceptibility
• Vaccines
• Agricultural practices
• Human Demographics and Behavior
• International Travel and Commerce
• Breakdown of Public Health Infrastructure
• Poverty and Social Inequality
• War and Famine
• Lack of Political Will
• Intent to Harm

Environment

• Climate and Weather
• Changing Ecosystem
• Technology and Industry
• Uncontrolled urbanization and population displacement

Lassa Fever

• The first episode of Lassa fever in Nigeria emerged in 1969 in Lassa village (Borno State, North East Nigeria) but was isolated from the blood sample of a missionary nurse who had sought treatment in Jos, Plateau state (North Central region of Nigeria)
• Then Lassa outbreak occurred in Jos in 1970, 28 persons were reportedly infected, of which 13 died
• A third episode in 2012 infected over six hundred persons and killed over 70 in 19 of the 36 states. Barely four years later, the country witnessed a re-emergence of the same epidemic- prone disease with 430 suspected cases and 40 deaths in 14 states in 2015. All these episodes also had nosocomial transmissions
• Since 2015, outbreaks are being reported almost yearly
• Nigeria’s population size in addition to it behavioural, nutritional and hygiene practices, cultural beliefs, poor environmental practices and massive inter/intra centre movement are the drivers of the disease transmission

Ebola Virus Disease

• The West African Ebola epidemic was the most widespread Ebola virus disease outbreak in history causing significant mortality with a total of 28,616 suspected cases and 11,310 deaths.
• The first case in Nigeria was a Liberian-American, who flew from Liberia to the city of Lagos on 20 July 2014.
• He set off a chain of transmission infecting 20 people out of which 8 deaths including the imported case and four health workers who had cared for the index case
• The outbreak was reported to have been effectively controlled using the incident management approach, strong public awareness, early engagement of traditional, religious and community leaders and massive support from the private and international community
• The WHO's representative in Nigeria officially declared the country Ebola-free on 20 October 2014, after no new active cases were reported in the follow up contacts, stating it was a "spectacular success story"
• Nigeria was the first African country to be declared Ebola free

Yellow Fever

• Yellow fever which is endemic to Africa was first discovered in Cuba.
• Nigeria has had several documented episodes of yellow fever outbreaks like the 1946 outbreak in Ogbomosho, 1951-1953 in eastern Nigeria and 1969 in Jos.
• Another outbreak was reported on 14 September 2017 when a 7 year old girl developed symptoms and as of 19 December 341 suspected cases and 45 probable and 9 confirmed deaths had been reported in 16 states of the federation inluding Kwara State
• The most recent outbreak was in Edo state in Sep 2018, from 22 Sep to 31 Dec 2018 a total of 146 suspected cases, 42 presumptive positive and 32 confirmed cases with 26 deaths across 15 of 18 LGAs in Edo State.
• The outbreak was attributed to vector-borne transmission and low vaccine coverage, hence WHO recommends vaccination and vector control for the prevention and control

Covid-19

• In December 2019, cluster of cases of viral pneumonia of unknown aetiology (now known as COVID-19) was reported in Wuhan, China
• Declared a Public Health Emergency of International Concern (PHEIC) by World Health Organization (WHO) on 31st January 2020 and a pandemic on March 11, 2020
• Nigeria recorded it first case on February 27, 2020
• The index case was an Italian man who arrived Lagos on February 24 from Milan via Murtala Muhammed airport, he proceeded to his company site in Ogun State the following day
• Spectrum of the disease ranges from asymptomatic to critical, including mortality
• As at 22nd of December 2022, Nigeria has recorded a total of 5,708,974 cases and 3,155 deaths

Infectious agent

• Novel agent or one not previously associated with disease
• No known treatment or cure
• Unknown reservoir
• May not initially be recognized as the causative agent of the disaster

Disease

• Not characterized previously
• Medical community lacks experience identifying and treating
• Symptoms are similar to other infectious diseases
• Indiscriminate use of antibiotics

Transmission

• Contagious agent – large number of secondary cases over time when no control measures are in place
• Global response may be necessary to contain agent
• Multiple cities affected
• Disaster could last weeks, months, years or decades

Personnel

• Inadequate public health work force
• Exposure of response personnel to infectious agent
• Healthcare workers absenteeism due to concern of contracting agent.
• Insufficient preparedness to control disease epidemics

Resources

• Isolation of cases in the healthcare facility.
• Decontamination of hospital equipment
• Destroyed infrastructure
• Capacity of laboratory to process samples
• Distribution of limited supplies (drugs, equipment).
• May be other infectious disease outbreaks concurrently

The public

• Quarantine and Isolation.
• Screening for symptoms (at hospitals, airports)
• Controlling movement (closed borders)
• Closing services (schools, churches, public transportation)
• Psychological fears
• Media relations

Ethics and law

• Mass vaccinations
• Quarantine/restriction of movement
• Allocation of resources
• Demands on healthcare workers, first responders.

Vaccination programmes

• Limited vaccination coverage.

Surveillance

• Surveillance gaps for some important diseases/inadequate surveillance.
• Delay in reporting, poor analysis of data and information at all levels
• No sufficient feedback to periphery
• No evaluation

• Microbial adaptation: more appropriate use of anti-microbial agents to prevent the emergence of resistance strains
• Human susceptibility: promotion of healthy life style and where available the use of vaccines to boost herd immunity.
• Vaccines are one of the most successful public health tools to improve the health of populations. By preventing infectious diseases, vaccines limit human suffering and the spread of contagious agents
• International travel and commerce: International collaboration to maintain surveillance and necessary containment strategies to limit importation of disease from affected to unaffected territories
• Economic Development and Land use: Conducting detailed analysis of the possible health impacts of massive deforestation programmes and implementing measures to mitigate those likely impacts
• Climate and weather: Global cooperation to reduce global warming and adopt eco-friendly strategies
• Agricultural practices: this includes food safety programs and animal control programs, if contamination is found in representatives of any batches of food from industries, public health officials recall the entire batch and alert the public through the media