We’re the Survivors

Hosts and pathogens have a profound evolutionary influence on each other.

Host------------> increased resistance

Pathogen--------->decreased virulence

Balanced Polymorphismselection that maintains a

genetic disease in a population because heterozygotes resist an infectious disease

Heterozygote advantage

Malaria is one of leading causes of morbidity and mortality in the developing world (along with TB, acute respiratory syndrome, diarrhea and HIV) but still not recognized in developed countries as a disaster like AIDS or EBOLA.

Each year, 300-500 million people become ill with malaria.

More than 2 million people, mostly children, die from malaria each year.

Around 2.5 billion people (at least 40% of the world’s population) are at risk in over 90 countries.

Malaria kills more people today than three decades ago. Reasons include:

Increasing drug resistance

Increased migration and immigration

People moving from countryside to cities.

Tourist and business travel Decreased mosquito control

Deforestation

Pathogen:Plasmodium falciparum(and 3 other plasmodium species)

Vector:female ‘Anopheles’ mosquitoes

Symptoms:fever, chills, headache, muscle ache.

Every six months nets are dipped in insecticide and dried before use.

Sickle cell anemia-------malaria

Cystic fibrosis-------cholera

Tay Sach’s disease----tuberculosis

HH Hh hh

CC Cc cc

TT Tt tt

How Mutation SpreadsInfectious Disease

Altered host (eg: parvovirus) New toxin (eg: Eco 157:H7 invasive Strep A) New route of transmission (eg: Ebola) Drug resistance