Re-emerging infections

What is the definition of a reemerging infection?

A reemerging infection is an infectious disease that has been previously controlled or reduced to low levels in a population but is once again on the rise.

List three key factors that contribute to the re-emergence of infectious diseases.

Three key factors are antibiotic resistance, declining vaccination rates, and increased global travel.

How does the measles virus cause a unique phenomenon known as "immune amnesia"?

The measles virus suppresses the immune system by depleting memory T and B cells, weakening the body's immune response to other pathogens.

What are the two main routes of transmission for the poliovirus?

The poliovirus primarily spreads through the faecal-oral route, but can also spread through oral-oral transmission via respiratory droplets.

What is the primary cause of paralysis in a poliovirus infection?

Paralysis occurs when the virus invades the central nervous system and destroys motor neurons in the anterior horn of the spinal cord and the brainstem

What is Vaccine-Derived Poliovirus (VDPV) and how does it cause outbreaks?

A VDPV is a strain of poliovirus that has mutated from the weakened live virus in the oral polio vaccine (OPV) and regained the ability to cause paralysis, typically spreading in under-immunized populations.

What are the three distinct clinical stages of pertussis (whooping cough)?

The three stages are the:

• Catarrhal stage (cold-like symptoms)

• Paroxysmal stage (severe coughing fits)

• Convalescent stage (gradual recovery).

What is the function of Pertussis Toxin (PTx), a key virulence factor of Bordetella pertussis?

Pertussis Toxin is an AB5 exotoxin that disrupts host cell signalling by interfering with G-proteins, leading to increased cAMP levels, which weakens immune cells like neutrophils and macrophages.

How does Filamentous Hemagglutinin (FHA) contribute to the virulence of Bordetella pertussis?

FHA is a surface protein that facilitates bacterial adhesion to the ciliated epithelial cells in the respiratory tract, allowing the bacteria to establish infection.

Why has the switch from whole-cell (wP) to acellular (aP) pertussis vaccines been linked to the disease's reemergence?

Acellular vaccines (aP) are safer but may not provide as durable or broad long-term immunity as the whole-cell (wP) vaccines, leading to waning immunity.

How does environmental change, such as deforestation, contribute to disease re-emergence?

Environmental changes alter ecosystems, potentially bringing humans into closer contact with disease vectors like mosquitoes or ticks, contributing to the re-emergence of vector-borne diseases like malaria.

What is post-polio syndrome?

Post-polio syndrome is a condition that can develop decades after the initial infection, characterized by new progressive muscle weakness, fatigue, and joint pain.