Introduction to emerging and re-emerging

What are emerging and re-emerging infectious diseases? EIs - newly identified /unknown infections which cause public health problems locally or globally

Term includes infections spreading to new geographic areas and those diseases that were responding to antibiotics but are now resistant<br>

Not always possible to know if these diseases are new in humans, or whether were present but unrecognized throughout the years
EIs thought to be due to a closer contact of man with their reservoirs in nature, with a successful «jump» of the infectious agent from animal to man across the species barrier<br>

Examples of EIs HIV infection which causes AIDS, with its sequelae of human suffering and economic burden
Ebola hemorrhagic fever with a potential for international spread
Other examples of new or newly detected infectious diseases of global concern include a new form of cholera
hepatitis C and hepatitis E
Legionnaires’ disease, and Lyme disease, dengue fever, West Nile virus, and the Zika virus.
COVID<br>

Re-emerging infectious diseases infections that have appeared after significant decline in their incidence
often reappear in epidemic proportions.
Tuberculosis increasing worldwide due in part to its close association with HIV infection
cholera re-introduced into countries and continents where it had previously disappeared, and where it can spread because water and sanitation systems have deteriorated
dengue or «breakbone» fever has started to occur in urban areas where mosquito control has broken down.<br>

Reemerging diseases include
Malaria, Tuberculosis, Cholera, Pertussis, Influenza, Pneumococcal disease, and gonorrhea.
Ebola , Marburg
Crimean congo haemorrhagic fever
Lassa fever
MERS, SARS
Nipah, Rift valley fever
Covid<br>

Why are these diseases emerging? Emergence is multifactorial in origin:
Rapid population growth – uncontrolled urbanization- crowded cities- unhygienic conditions that provide breeding ground for pathogens
intense international travel and growing trade and tourism
Migration and displacement of people due to war, strife or disasters
Agricultural practices<br>

changes in handling and processing of large quantities of food;
and increased exposure of humans to disease vectors and reservoirs in nature.
Mutations that lead to new strains; and drug resistance; Resistance of vectors to pesticides
Most significant factor: deteriorating public health infrastructure which is unable to cope with population demands, and the emergence of resistance to antibiotics linked to their increased misuse.<br>

Bioterrorism Possible deliberate release of infectious agents by dissident individuals or terrorist groups
Biological agents are attractive instruments of terror‐ easy to produce, mass casualties, difficult to detect, ‐ B. anthracis, C. botulinum toxin, F. tularensis, Y. pestis, Variola virus, Viral haemorrhagic fever viruses
Likeliest route‐ aerosol dissemination<br>

During first half of the 20th century deaths from infectious diseases declined because of improved hygiene and nutrition. This trend was strengthened with the advent of vaccines and antibiotics during the 1940s and culminated in the late 1970s in the eradication of one infectious disease, smallpox. Because at that time infectious diseases appeared to be a decreasing threat, funds for their control were channeled to other problems, experts on infectious disease retired or left the field and students turned to more rewarding subjects than viruses and bacteria - the infrastructure for communicable disease control began to crumble.<br>

Emerging and re-emerging infections reflect the constant struggle of microorganisms to survive.<br>

Transmission of Infectious Agent from Animals to Humans‐ ZOONOTIC diseases >2/3rd emerging infections originate from animals‐ wild & domestic e.g Emerging Influenza infections in Humans associated with Geese, Chickens & Pigs
Animal displacement in search of food after deforestation/ climate change (Lassa fever)
Humans themselves penetrate/ modify unpopulated regions‐ come closer to animal reservoirs/ vectors (Yellow fever, Malaria)<br>

Impact of EIs Economic
Social
Public health<br>

PRIORITY AREAS FOR ACTION 1. STRENGHTHENING NATIONAL CAPACITIES
Create early warning systems and rapid response mechanisms
Strengthen epidemiological laboratory and systems
Early action for prevention and control<br>

2. Intersectoral collaboration Constant dialogue about the health implications of projects in other ministries
Close collaboration between health and other ministries<br>

Intercountry collaboration Rapid flow of disease surveillance between countries<br>

The global response Since 1992 alarm over emerging and re-emerging diseases resulted in a number of national and international initiatives to restore and improve surveillance and control of communicable diseases. Member States of WHO expressed their concern in a resolution of the World Health Assembly in 1995, urging all Member States to strengthen surveillance for infectious diseases in order to promptly detect re-emerging diseases and identify new infectious diseases. The WHA recognized that the success of this resolution depends on ability to obtain information on infectious diseases and willingness to communicate information nationally and internationally.<br>

The World Health Organization warned in its 2007 report that infectious diseases are emerging at a rate that has not been seen before. Since the 1970s, about 40 infectious diseases have been discovered, including SARS, Ebola, Avian flu, and Swine flu<br>

Surveillance and Response 
Global Outbreak Alert & Response Network Coordinated by WHO Mechanism for combating international disease outbreaks
Ensure rapid deployment of technical assistance, contribute to long‐term epidemic preparedness & capacity building
Applied Research 
Infrastructure and Training 
Prevention and Control<br>

Conclusion Infectious diseases will continue to dominated disease scenarios in most countries.
The most sustainable way to deal with them is through early detection and rapid response.<br>