HLSC 4P03 - Global Issues in Infectious Diseases

What are some infectious agent categories?

Bacteria (prokaryotes)

Fungi (eukaryotes)

Viruses (complex molecules)

Prions (proteins)

Protozoa

Helminths

Arthropods

What species make up the Eukaryotic Parasites

Protozoa, Helminths, Arthropods

What are the epidemiological states a living individual is assumed to be in at any given time?

Susceptible, Infected and Infectious, Recovered

Factors involved in Infectious Disease Emergence

• International trade and commerce

• human demographics and behaviour

• human susceptibility to infection

• poverty and social inequality

• war and famine

• breakdown of public health measures

• technology and industry

• changing ecosystems

• climate and weather

• intent to harm

• lack of political will

• microbial adaptation and change

• economic development and land use

HMPV?

New virus outbreak in China, Human Metapneumovirus

Where was the first human case of Monkeypox discovered?

Democratic Republic of the Congo (DRC) in 1970

Emergence of novel human pathogens from livestock and wild mammal and bird reservoirs

Zoonosis, Spillover

What does the Epidemiologic triad consist of

Agent → Environment → Host

What is SDG?

Sustainable development goals, adopted in September 2015, set to be achieved by 2030. They are a follow-up to the millennium development goals (MDGs).

What is SDG #3

Ensure healthy lives and promote well-being for all at all ages
“End the epidemics of AIDS, tuberculosis, malaria, and neglected tropical diseases and combat hepatitis, water-borne and other communicable diseases”.

What sis SDG target 3-3

Fight Communicable Diseases

What is Spillover

An event during which a pathogen from one host population (or reservoir) to another host population

What is spillback

Where the transmission is from a spillover host back into the maintenance host species from which it originated.

What does Spillover come from?

complex bidirectional interactions among people, animals, pathogen communities, and environment

When and where did spillover first occur

Probably occurred in the southeastern corner of Cameron around 1908
“possibly a wildlife hunter or a butcher, unwittingly became infected with a chimpanzee virus while handling a prized primate catch”

Who was the first human known to be infected with HIV

man from Kinshasa in the nearby DR of Congo, who had his blood stored in 1959 as part of a medical study.

Due to societal bias and ignorance, the syndrome (HIV) was dubbed with many pejoratives in the early 80s

• “Gay compromise syndrome"

• GRID (gay-related immune deficiency)

• AID (acquired immunodeficiency disease)

• “Gay cancer"

• “Community-acquired immune dysfunction”

Before the 1980s approx how many people were infected with HIV in the USA?

+ 100,000 to 300,000

What did Robert Gallo Discover?

Led to the discovery or reverse transcriptase

HIV-1

• The most common HIV type (cause of pandemic)

• Cases recognized in 1981

• Virus identified in 1983

• •Presents 4 main sub-types (M, O, N, P)

HIV-2

• Discovered in 1985

• Distributed mainly in West Africa or population movements from or through this region

• Closely related to the SIV from sooty mangabeys (SIVsm) found in West Africa

• Less common and less virulent

The seven stages of the HIV life cycle

1) binding 2) fusion 3) reverse transcription 4) integration 5) replication 6) Assembly 7) budding/latency

What is the hallmark of the HIV infection

T cell dysfunction, including exhaustion and progressive depletion of CD4+ T cells

What are the 5 conditions for HIV transmission?

1. there must be a source of infection

2. there must be a means of transmission

3. there must be a host susceptible to transmission

4. there must be an appropriate route of entry to the target cells of the body

5. there must be a sufficient level of virus delivered to establish infection

the S in AIDS

AIDS is a syndrome, rather than a single disease, because it is a complex illness with awide range of complications and symptoms

Several chemokine receptors are mediators of HIV-1 entry

CCR5 (Double mutation CCR5 makes people virtually immune to R5 HIV) and CXCR4

Single mutation makes the disease progression slower

Elite controllers (aka LTnP)

have the ability to naturally suppress HIV-1 replication to levels undetectable by current viral load assays (<50 RNA copies/mL)

Due to host genetic variability: HLA complex, Antibody-dependent cellular cytotoxic (ADCC) activity, etc.

The Berlin Patient, London Patient, U.S. Patient

all people virtually cured of HIV from stem cell or bone marrow transplants

how many people become infected everyday?

4000

AIDs and SDGs

Goal 1: end poverty

Goal 2: end hunger

Goal 3: ensure healthy lives

Which exposure category remains the largest proportion of new HIV diagnoses

Male to male sexual contact

Many drivers that may contribute to the HIV epidemic among gbMSM* in Canada, for example:

–Therapeutic optimism since the introduction of effective ART

–The dynamics of sexual networks

–The high transmission efficiency of receptive anal intercourse

–Stigma limiting access to services