CPH Lec Week 15 (Part2)

Andrea Barrett

___ said “Infectious disease exists at this intersection between real science, medicine, public health, social policy and human conflict”

microbes

Humans have coexisted with ___ since the dawn of time

Vibrio cholera

The early study of infectious diseases—such as cholera, caused by ___, played a critical role in the birth of epidemiology

antibiotics and vaccines

Despite advancements like ___ and ___, infectious diseases remain a major global health threat, particularly due to their constant evolution and the emergence of new pathogens (e.g., SARS, MERS) and re-emergence of old ones (e.g., TB, Ebola)

social determinants

Infectious diseases are more than just a biological phenomenon; they are closely tied to __

Genetics and personal health

social determinants of Infectious diseases

• ___

• Access to sanitation and nutrition

• Socioeconomic status

Access to sanitation and nutrition

social determinants of Infectious diseases

• Genetics and personal health

• ___

• Socioeconomic status

Socioeconomic status

social determinants of Infectious diseases

• Genetics and personal health

• Access to sanitation and nutrition

• ___

poverty and marginalization

Because of this, infectious disease prevalence often reflects ___ and ___

rapid evolution

microbes have ___ which makes them resistant to drugs (e.g., antibiotic resistance)

Convergence Model

The ___ offers a structured way to understand how infectious diseases emerge.

Genetic & Biological factors

Convergence model:___

• Individual immunity, pathogen virulence

Physical Environment

Convergence model:___

• Climate, urban infrastructure, sanitation

Ecological factors

Convergence model:___

• Animal reservoirs, deforestation, migration

Social, Political & Economic factors

Convergence model:___

• Healthcare access, governance, poverty

Surveillance and outbreak investigation

Effective control and prevention must be comprehensive and proactive, involving:

• ___

• Strengthening health systems

• Targeted vaccination programs

• Addressing root causes like sanitation, education, and equity

• Global cooperation in monitoring and response

Strengthening health systems

Effective control and prevention must be comprehensive and proactive, involving:

• Surveillance and outbreak investigation

• ___

• Targeted vaccination programs

• Addressing root causes like sanitation, education, and equity

• Global cooperation in monitoring and response

Targeted vaccination programs

Effective control and prevention must be comprehensive and proactive, involving:

• Surveillance and outbreak investigation

• Strengthening health systems

• ___

• Addressing root causes like sanitation, education, and equity

• Global cooperation in monitoring and response

Addressing root causes like sanitation, education, and equity

Effective control and prevention must be comprehensive and proactive, involving:

• Surveillance and outbreak investigation

• Strengthening health systems

• Targeted vaccination programs

• ___

• Global cooperation in monitoring and response

Global cooperation in monitoring and response

Effective control and prevention must be comprehensive and proactive, involving:

• Surveillance and outbreak investigation

• Strengthening health systems

• Targeted vaccination programs

• Addressing root causes like sanitation, education, and equity

• ___

Epidemiologic investigation

Taking sensitive histories (e.g., sexual behavior, travel history), outbreak tracking, analyzing disease patterns by demographics

Communication and outreach

Educating both the public and healthcare providers, reducing stigma, and promoting healthy behaviors

Direct interventions

Screening, contact tracing, vaccination, prophylactic treatments, and school health policies

Environmental controls

Sanitation, safe water and food handling, waste management, and vector control.

Structural support

Building and maintaining disease registries, improving healthcare access, and ensuring systemic preparedness.

Epidemiologic investigation ; Communication and outreach ; Direct interventions ; Environmental controls ; Structural support

Prevention pathways

• ___

• ___

• ___

• ___

• ___

Improving Host Resistance ; Improving Environmental Safety ; Improving Public Health Systems

Three Pillars of Prevention

• ___

• ___

• ___

Improving Host Resistance

One of the Three Pillars of Prevention focuses on boosting individual defenses

Improving Environmental Safety

One of the Three Pillars of Prevention that is about making the surroundings less conducive to disease

Improving Public Health Systems

One of the Three Pillars of Prevention focuses on a strong system amplifies response capabilities

Understanding a disease’s mode of transmission is critical

A key message: ___. Once this is known, we can design appropriate interventions

John Snow

___’s classic cholera study illustrates this beautifully. By tracing cholera cases to a contaminated water pump, he was able to halt the outbreak simply by removing access to the source.

John Snow’s classic cholera study

This is the foundation of modern disease mapping and intervention

Airborne, Fecal-oral, Vector borne, Sexually transmitted, and Bloodborne

Diseases are often grouped by transmission: ___, ___, ___, ___, and ___

know how it spreads

Each transmission category requires a different control strategy, but all starts with the same first step: ___

Emerging and reemerging infections

However, since the 1980s, there has been a resurgence of infectious disease burden due to ___ and ___

antimicrobial resistance, changing pathogens, and global movement of people and goods

The resurgence of infectious disease reflects the evolving challenges in infectious disease control: ___, ___, and ___

Dengue fever, Chagas disease, and deadly Ebola outbreaks

___, ___, and ___ show that new and neglected diseases still pose real threats, especially in under-resourced regions

Acute respiratory infections ; Measles ; Diarrhea ; Malaria ; Pediatric HIV/AIDS

Infectious diseases remain a leading cause of childhood mortality, particularly in the poorest countries:

• ___

• ___

• ___

• ___

• ___

Disability-Adjusted Life Years (DALYs)

Combines premature death and years lived with illness/disability. Reflects the true cost of disease, not just in lives lost, but in years of life not lived to full potential

HIV/AIDS, Lower respiratory infections, Diarrheal diseases, Malaria, and Tuberculosis

Globally, 5 out of the top 10 causes of DALYs are infectious: ___, ___, ___, ___, and ___

eating and hygiene habits, pets in residence, illicit drug use, and sexual partners

Transmission of major infectious diseases often results from a person’s behavior, including ___ and ___, ___, ___, and ___

behavioral history

caring for a patient with an infectious disease requires taking a careful ___

income inequality ; immigration and international travel

HIV/AIDS, malaria, TB also impact on developed countries, either internally through___ or externally through ___ and ___.

acquired immunodeficiency syndrome

No new disease in modern times has had as severe and global impact as ___, which is caused by the human immunodeficiency virus

antiretroviral therapy (ART)

___ doesn’t cure HIV but dramatically improves life expectancy and reduces transmission

sexual contact or needle sharing

Horizontal Transmission of HIV is most commonly in adults via ___ or ___

heterosexual intercourse

Globally, ___ is the primary route for HIV

men who have sex with men (MSM)

In the U.S., highest transmission rates for HIV are among ___

Pregnancy ; Birth ; Breastfeeding

Vertical Transmission of HIV is from mother to child: during ____, at ___, and Through ___

Occupational exposure and Contaminated blood transfusions

Less Common Routes for HIV are through ___ and ___

Condom use

Still one of the most effective and affordable methods of preventing the spread of HIV

Pre-exposure prophylaxis (PrEP)

Antiretroviral medications for high-risk individuals to prevent infection of HIV

Treatment as prevention

When an HIV infected individual’s viral load is suppressed through ART, the risk of transmitting the virus is drastically reduced

Mother-to-child

HIV transmission prevention: Includes ART during pregnancy and avoiding breastfeeding when possible

Male circumcision

Reduces heterosexual HIV transmission risk in some regions

Surveillance and capacity building

Helps track HIV outbreaks and strengthen responses

opt-out

CDC Recommendations for HIV screening is through ___ screening for all patients aged 13 to 64

Centers for Disease Control and Prevention

Recommended by the ___: Routine, opt-out screening for all patients aged 13 to 64

United States Preventive Services Task Force

Recommended by the ___: Screening for ages 15 to 65 and anyone else considered high-risk

Tuberculosis

___ remains one of the most persistent and complex infectious diseases in global public health. It has a long history, complicated disease dynamics, and growing drug resistance

streptomycin

After the discovery of ___ and other TB drugs in the 1940s, control improved greatly

Multidrug-Resistant TB and Extensively Drug-Resistant TB

TB management is severely challenged by drug-resistant forms: ___ and ___

isoniazid and rifampin

Multidrug-Resistant TB are resistant to ___ and ___, the two main firstline drugs

costlier

Multidrug-Resistant TB Requires longer, ___ treatments with more side effects

second-line therapies

Extensively Drug-Resistant TB are Resistant to ___ as well

Extensively Drug-Resistant TB

type of drug resistant TB that is often considered virtually untreatable

latent TB infection (LTBI)

After exposure to TB, most people develop ___:

• Noninfectious

• Can remain dormant for life

• Diagnosed by tuberculin skin test (PPD) or interferon-gamma release assays (IGRAs)

• 5–10% of infected individuals may later develop reactivation TB, especially if their immune system is weakened

Primary TB

initial active infection of TB

Latent TB (LTBI)

TB where infection controlled but not eliminated.

Reactivation TB

TB where dormant infection becomes active again

Reinfection TB

TB where new infection after prior clearance

Bacille Calmette-Guérin (BCG) vaccine

The first discovery for a TB vaccine derived from a live, attenuated mycobacterium called ___

housing and air quality

Improving ___ (especially in shelters and prisons) can reduce he risk of TB

latent TB

Secondary prevention for TB only identifies ___ through testing

Directly Observed Therapy Short Course (DOTS)

The ___ strategy is key to combating TB globally

Political commitment and sustained funding

five pillars of DOTS are:

• ___

• Reliable detection and diagnostic capacity

• Standardized treatment regimen with patient support

• Uninterrupted drug supply

• Robust monitoring and evaluation systems

Reliable detection and diagnostic capacity

five pillars of DOTS are:

• Political commitment and sustained funding

• ___

• Standardized treatment regimen with patient support

• Uninterrupted drug supply

• Robust monitoring and evaluation systems

Standardized treatment regimen with patient support

five pillars of DOTS are:

• Political commitment and sustained funding

• Reliable detection and diagnostic capacity

• ___

• Uninterrupted drug supply

• Robust monitoring and evaluation systems

Uninterrupted drug supply

five pillars of DOTS are:

• Political commitment and sustained funding

• Reliable detection and diagnostic capacity

• Standardized treatment regimen with patient support

• ___

• Robust monitoring and evaluation systems

Robust monitoring and evaluation systems

five pillars of DOTS are:

• Political commitment and sustained funding

• Reliable detection and diagnostic capacity

• Standardized treatment regimen with patient support

• Uninterrupted drug supply

• ___

Malaria

remains one of the world’s most deadly infectious diseases, especially in low-income, tropical regions. It poses a unique challenge due to its complex life cycle, the persistent presence of a mosquito vector, and the lack of long-term immunity in human hosts

Plasmodium ; female Anopheles mosquito

Malaria is a vector-borne disease caused by the protozoan parasite ___, transmitted by the ___

Plasmodium falciparum

most deadly, common type of plasmodium species in Africa

Plasmodium vivax

more common type of plasmodium in Asia and the Americas

red blood cells (RBCs)

These plasmodium parasites infect ___, where they multiply and cause the cells to rupture (hemolysis)

Parasite ; Vector ; Host ; Environment

Malaria transmission depends on several interconnected factors:

• ___

• ___

• ___

• ___

partial immunity

Individuals living in endemic areas may develop ___ over time through repeated exposure to malaria. However, this immunity is not lifelong and can fade if exposure stops

long-lasting immunity,

Unlike many viral diseases, malaria does not confer ___ making reinfection possible

chloroquine

Original malarial treatments like ___ are no longer effective in many regions due to widespread resistance

RTS, S vaccine

first generation malaria vaccine

Prophylaxis

___ is recommended as a secondary prevention to malaria for travelers and vulnerable populations

close-contact disease spectrum

The ___ ranges from the common cold, which causes some loss of work, to diarrheal illnesses, which kill millions of children in developing countries

acute respiratory infections ; acute gastrointestinal illnesses

Many close contact diseases are also seasonal: ___ peak in the winter, whereas most ___ peak in the warmer months.

reproductive number (R0)

An important concept in acute respiratory infection epidemiology is the ___

b(a)

where ___ is the average number of people infected by an index case per unit time

F(a)

___ is the probability that a newly infected person remains infectious for at least time a

da

__ is the period of infectivity

25 R0

___ indicates an agent’s transmissibility and helps estimate the vaccine coverage required to induce herd immunity

Viral hepatitis

___ is an important cause of local and sporadic outbreaks