Political Sidenote:

• 0.1% of US GNP is devoted to foreign aid, mostly military
• Þ we could be doing a lot more to eradicate disease across the globe

• Impediments to Control
• money
• social upheaval
• poor local and central government control (mismanagement; lack of $, etc)
• disease of poor people in rural areas (harder to get governments and people to care), but these diseases are a huge burden to the economy
• increasing current measures is limited by cost and resistance
• Basics of Control
• biology of pathogen and the host (life cycles, modes of transmisison, etc)
• epidemiology of both infection and disease, and regulatory factors
• knowledge of basic science
• define target for control
• do we want to prevent infection, disease, transmission, or eradicate the bug?
• then we need to decide who to target (everyone, infected people, diseased people?)
• Strategies for Control
• chemotherapy: effective for shistosomiasis, malaria
• vector control: kill mosquitoes for malaria, snails for shisto
• vaccines
• environmental modification: malaria control in US through drainage of mosquito-laden swamps
• development
• population based control programs (i.e. vaccinate everyone!): have had most success
• Example: attempted control of shistosomiasis in Kenya
• Key Aspects of Shisto Control
• infection ¹ disease
• shisto doesn’t replicate in humans Þ extent of disease related to innoculum
• disease is mediated by host immune response to the parasite eggs
• cumulative effect: can keep picking up more and more parasites
• Options: chemo; health education; provide safe water supply; snail control; chemo chosen for Kenya
• Target population: symptomatic people
• chemo given only to people presenting with clinical symptoms
• can be implemented in existing health care system
• only good when prevalence is low
• Target population: community
• good when prevalence and transmission are high
• selective population chemo: whole population screened, infected people treated
• selective group chemo: treat most heavily infected people
• children 10-14 are most heavily infected and were the group chosen for chemo treatment
• Results: during the treatment period, shisto was somewhat controlled, but there was no lasting effect as demonstrated by a follow-up study
• Example: malaria control
• mosquito vector was determined to be the most important part of the life cycle
• swamps were drained, DDT used to kill mosquitoes, surveillance and treatment Þ eradication of malaria from US
• same techniques applied in 50’s and 60’s worldwide
• surveillance broke down in the 70’s and there is now a huge resurgence of malaria worldwide