2. Learning objectives
• What is emerging and re emerging infections
• Factors responsible for emergence and re-emergence of infections
• Emerging infectious diseases: Ebola virus, Zika virus, Nipah virus, Lassa fever
• Examples of re-emerging infectious diseases
• Public health actions to be taken
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3. Emerging infectious diseases
(New diseases; New Threats)
Defined as:
• Those which were not experienced previously
• Those with already known causative agents but –
• Not previously known to infect humans OR
• Occuring in new regions where previously they were not existent OR
• Occuring in new age group with new clinical features AND
• Developing resistance to existing treatment
• Examples :
• AIDS after 1981
• Vibrio cholera O139 emerged in 1992
• ACT resistant malaria
• MDR and XDR tuberculosis
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4. Re-emerging Infectious Diseases
(Old diseases; New Threats)
• Re emerging infectious diseases are those which was previously controlled and efficaciously
treated but have recurred in a new epidemiological setting with increased frequency and mortality
or in a more virulent form to be a significant public health problem.
• Due to development of resistance by the organism for the drugs OR by the vector for the
pesticides/insecticides
• Example: Malaria, dengue
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5. Factors
• Improper planning of township
• Population explosion, poor living condition with overcrowding
• Industrialization/urbanization
• Lack of proper health care services
• Intense international travel
• Indiscriminate use of antibiotics
• Increase contact with animals
• Environmental degradation with changing weather pattern
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6. Emerging infectious diseases
They can be grouped into 2 groups
D/t new agents d/t new variant of old pathogen
Ebola virus disease * 0157.HF strain of E.coli
Zika * Exanthem subitum
Nipah and hanta virus * 0139 strain of cholera
Lassa fever
MERS
SARS
RVF
CCHF
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8. Introduction
• A serious viral hemorrhagic fever (EHF)
• Initially detected in 1976 around ebola river of Zaire (DRC)
• 35 outbreaks occurred from 1976 – 2016
• Largest outbreak in west Africa in 2014 – 2016
• In 2014, declared as PHEIC by WHO
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9. Epidemiological determinants
Agent
RNA Virus
Family: Filoviridae
5 species: reston
virus has not caused
disease in human yet
2014 outbreak: zaire
species
Reservoir
Animal borne virus
Monkeys, gorillas,
chimpanzees
Fruit bat are natural
host
Infective material
Blood & body fluids:
urine, saliva, sweat,
feces, vomitus,
breast milk, semen
of infected person
Fomites: needles,
surgical instruments
Mode of transmission
Close contact with
blood and body
secretion of infected
animal
Direct contact
transmission
between humans
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13. Treatment & Prevention
• No specific treatment available, only supportive care
• Vaccines are under different phases of trial
• PRECAUTIONS:
• Use of disposable medical equipments
• Sterilization of surgical instruments
• Personal precautions
• High standard of personal hygiene
• Avoid contact with bats, non human primates or blood, body fluid or raw meat from these
animals
• Avoid sexual contact with person who have recovered from ebola
• After returning from endemic areas, health should be monitored for 21 days09-10-2020 13
15. Introduction
• Till 1952, zika virus was known to be the disease specific to monkeys
• The largest outbreak in 2015 – 2016 affected >33 countries
• Declared a PHEIC by WHO on 1st feb 2016
• India has recorded its biggest outbreak with > 100 cases in October 2018 from state of Rajasthan.
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16. The virus
• Icosahedral, enveloped, single stranded RNA virus
• Arbovirus of genus Flavivirus
• Transmitted by bite of Aedes mosquito
• Also transmitted
• from pregnant mother to fetus
• Through sexual contact
• Hemotransfusion
• Organ transplant
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20. Clinical features
• IP = 3 – 14 days
• Duration of viremia = 3 days (3rd to 5th day after onset of symptoms)
• About 80% are asymptomatic
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26. Introduction
• Nipah virus disease is a zoonotic disease, associated with high fatality and virulence among people
• Mainly affects pigs (dogs, cats, horses and sheep may be affected)
• 1st recognised in Malayasia in 1999 when outbreak occurred among pig farmers
• Most recent outbreak occurred in India in kerala in 2018.
• Infects endothelial cells and neurons causing neurological symptoms
• Systemic vasculitis with extensive thrombosis and parenchymal necrosis in CNS are found.
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33. Introduction
• A zoonotic disease
• Viral hemorrhagic fever
• Virus:
• Family: Arenaviridae
• Single stranded retrovirus
• Transmitted by coming in contact with infected rodents (Mastomys rats)
• Reuse of contaminated medical equipments leads to person to person transmission
• Poor sanitary condition and overcrowding increases the risk
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38. Re-emerging infectious diseases
• Malaria: resurgence of malaria
• Kala-azar: was controlled but again it started to increase due to factors such as deforestation,
industrialization, urbanization, poor living condition, livestocks in the house.
• Dengue fever: re emerged due to factors pre disposing to breeding of Aedes aegypti mosquito and
development of insecticide resistance.
• Plague: during 1960s plague was totally under control but re emerged in 1994 in Maharashtra,
later in Surat, Delhi, Punjab.
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