AMSCO 9.2 Technological Advancements and Limitations Notes

Overview

AMSCO Topic 9.2, Technological Advancements and Limitations: Disease (AMSCO p.641-645), covers how diseases and medical breakthroughs shaped human populations after 1900. The chapter sorts disease into three buckets: diseases tied to poverty (malaria, tuberculosis, cholera, polio), new emerging epidemics (the 1918 flu, HIV/AIDS, Ebola), and diseases that show up more because people live longer (heart disease, Alzheimer's). The big takeaway for Unit 9 of AP World: science and public health campaigns wiped out or contained some diseases, but poverty, war, and aging populations kept others alive, and every outbreak pushed new medical technology forward.

The chapter opens with the biggest success story. Smallpox killed millions per year as recently as the 1960s, but a global vaccination campaign run by the World Health Organization (WHO) eliminated it. In 1979, scientists declared smallpox gone from the planet, except for a culture preserved at the Centers for Disease Control in the United States. This proved that coordinated global action could solve global problems, a theme that runs through the whole chapter.

This topic builds directly on the medical and scientific advances in AMSCO 9.1 Advances in Technology and Exchange.

Key Timeline

Timeline of diseases as they appear from 1900 to the present. Image courtesy of Vibhi.

Diseases Associated with Poverty

Some diseases persist even when cures exist, because poverty itself spreads them. Poor housing, unsafe working conditions, contaminated water, and lack of access to health care all keep these diseases circulating among low-income populations.

Malaria

• A parasitic disease spread by mosquitoes in tropical areas. In the early 21st century, malaria killed more than 600,000 people per year, most of them young African children.
• Doctors Without Borders, an international non-governmental organization (NGO), treated about 1.7 million malaria patients annually.
• Prevention has focused on insecticide-treated mosquito nets used while sleeping, but people can still be bitten during waking hours. An effective vaccine has been in development for years but remained in trials.
• Progress is real: in 2019, the WHO certified Algeria and Argentina as malaria-free. The catch is that some mosquitoes are becoming resistant to insecticides.

Tuberculosis (TB)

• An airborne infection of the lungs that spreads through coughs and sneezes.
• Before 1946, there was no effective drug treatment. Then a cure was developed using antibiotics plus a long rest period. In countries where TB is common, children receive vaccines.
• In the early 21st century, a drug-resistant strain appeared and infections rose, especially in prisons where people live in close quarters. The WHO launched a worldwide anti-TB campaign in the 2010s.

Cholera

• A bacterial disease spread through contaminated water, causing about 95,000 deaths per year, mainly among poor people in developing countries.
• A severe infection can kill within hours, but quick rehydration can effectively eliminate the risk of death.
• Prevention means boiling or chlorinating drinking water and washing hands. Vaccines exist but don't replace those basic measures.

Polio

• Spread by water contaminated with a virus from fecal matter. Polio once infected 100,000 new people per year and could cause paralysis or death.
• On April 12, 1955, American researcher Jonas Salk announced an effective injectable polio vaccine. Six years later, Albert Sabin's oral vaccine became available.
• A global campaign by governments, private organizations, and United Nations agencies began in 1988. In under 30 years, polio was eliminated almost everywhere.
• It survives in a few places like Pakistan and Afghanistan, where war makes vaccination difficult and political unrest and religious fundamentalism make people distrust programs pushed by outsiders.
• Like the smallpox campaign, polio eradication showed that coordinated global efforts can tackle global problems. That's a great piece of evidence for essays about international cooperation after 1900.

Emerging Epidemics

New diseases emerged after 1900 that caused major social disruption, and each one spurred new medical and public health responses. A quick vocab check: epidemics are widespread disease outbreaks, and pandemics are epidemics that spread across national borders.

The 1918 Influenza Pandemic

• In fall 1918, as World War I ended, a virulent flu strain swept the world. More soldiers died from the flu than from battle.
• One quarter of all Americans and one-fifth of the world's population became infected. The flu killed 20 million people worldwide, and its victims tended to be ages 20 to 40.
• It was so deadly that life expectancy in the United States dropped by 10 years, and more people died in 1918-1919 than in four years of the Bubonic Plague (1347-1351).
• Like the plague, the flu spread along trade routes and with military troops. That's a continuity worth remembering: disease still travels the same paths people do.

HIV/AIDS

• Acquired immunodeficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV), which weakens the immune system so patients more easily succumb to other illnesses. It spreads through bodily fluids: unprotected sex, blood transfusions, and shared intravenous needles.
• Between 1981 and 2014, AIDS killed more than 25 million people worldwide. Because the disease was associated early on with homosexual men and drug addicts, research funding was hard to secure, and a high percentage of the first victims died.
• By the mid-1990s, antiretroviral drugs could stop HIV from weakening the immune system, letting patients live with the virus for years. There's a treatment, not a cure.
• The drugs were expensive, so poor countries struggled to access them. Brazil is the standout exception: in 1996 it began providing free antiretroviral drugs to anyone who needed them. Deaths dropped dramatically, and the program actually saved the government money by reducing hospitalizations, medical leaves, and early retirements.
• After 2000, the WHO, the US government, and private groups increased funding for prevention and treatment, but in 2018 about 40 million people were living with HIV, mostly in developing countries or low-income areas of developed countries. More than 600 young women ages 15-24 become infected each week.

Ebola

• Discovered in the Congo in 1976, Ebola is a deadly virus that infects the African fruit bat, humans, and other primates. Humans catch it from the fluids of infected people or animals.
• It causes extensive bleeding and organ failure, and kills the majority of infected people.
• A massive 2014 outbreak in West Africa caused worldwide fear, but a coordinated, intensive public health effort contained and then ended it. The WHO led the response, issuing emergency warnings and implementing a "road map" for handling outbreaks. Like the polio campaign, this showed countries could work together against a shared danger.

Diseases Associated with Longevity

As people live longer, diseases that develop later in life become more common. These diseases appear most in countries with higher incomes, basically the flip side of the poverty diseases above.

Heart Disease

• The most common cause of death in developed countries, linked to lifestyle, genetics, and increased longevity.
• South African surgeon Christiaan Barnard performed the first heart transplant in 1967.
• Robert Jarvik led the team that designed an artificial heart, used as a temporary device while a patient waited for a compatible human heart.
• Less invasive fixes followed: valve replacements, stents in arteries, vessel replacements, and medications targeting the blood conditions behind heart disease. By the 2000s, heart disease patients lived longer than similar patients had in the 1970s.

Alzheimer's Disease

• A form of dementia affecting mostly elderly people (and some middle-aged people) that became a growing concern as longevity increased.
• Patients progressively lose their memory, eventually failing to recognize loved ones. Because the disease undermines bodily functions, it leads to death. Researchers are still searching for a cure.

Key Terms to Know

Practice and Next Steps

Pair these notes with Fiveable's Topic 9.2 course study guide on disease after 1900 for the College Board framing of the same content, then move on to AMSCO 9.3 Technology and the Environment. You can find the full set of chapter summaries on the AP World AMSCO notes page.

To check yourself:

• Run through guided multiple-choice practice on Unit 9 to test whether you can match diseases to their categories (poverty, emerging epidemic, longevity).
• Try FRQ practice with instant scoring using this chapter's evidence. The smallpox, polio, and Ebola campaigns are strong examples for prompts about global cooperation after 1900.
• Look up unfamiliar vocab in the AP World key terms glossary.