MG - Disease control

• Population can be split in to the susceptible group (s component), infected component and recovered component

Local elimination

• Usually use vaccines, breaking local chains of infection to limit the spread of infection

• If the population size is below the endemic threshold then the disease will die out

• Vaccination effects: increases the endemic threshold reduces number of people susceptible to the infection, reduce the number of infected people in the population that susceptible people can get the disease from

Measles

• 1978 – geographically widespread infection, US announced plan to eliminate measles
• 1982 – virtually no measles cases – but still strong measles activity in some areas such as California and Florida, as these are gateway areas where the disease is imported from other countries

• Prior to technological advances, distance became a natural geographical isolator. Measles epidemic in Fiji in 1875, virgin soil epidemic. But below endemic threshold so it died out. So therefore many regions of the world remain virgin soils. India was an important source for migrant labour for Fiji. Fiji too far from India for measles to still be active on sailing ships once they get there. Steam ships could reach Fiji with active cases of measles. Breakdown in natural isolation of distance.
• Quarantine ring in Venice manned by soldiers, there to stop people crossing quarantine line – would be stabbed or shot if you tried to cross the line without being checked

• Irac – boarder screening

  Demand that people be tested for HIV before they enter the country – if you didn’t do this then you would get a fine and if you didn’t pay this then you would get 6 months imprisonment  

• Infected area surrounded by areas that are disease free, build barrier to stop disease spreading out
• Foot and Mouth disease (FMD) virus disease (cows, sheep, goats, pigs)
• Infected herd will be killed to stamp out virus – has been recognised that by the time the disease has been stamped out in a herd, it has already spread somewhere else, can even be spread via the wind. Vaccines are available to control the spread of the virus. Blanket vaccination of all hooved animals in area that is likely to be infected within 20 days of the initially infected herd. Assume area surrounding herd is already infected-priorities vaccination between the 10-20 day wave front
• Blanket vaccination is most effective – but unrealistic as there are too many vaccinations

Combination of all

Halts spread of disease agent in nature

Malaria – 1955 WHO launched campaign to eradicate malaria – didn’t work and was abandoned

Ronald Ross identified role of mosquitoes

Attempts to kills mosquitoes – oil spread on surface to suffocate mosquito larvae – also used bombs to kill larvae – drained marshes as larvae are kept underground

In war always lose more soldiers to malaria than bullets

DDT – kills mosquito nervous system – began to be used all over the world

WHO said malaria would be gone by the 1990s – dramatically reduced in India and South America

Malaria was being described as a disease of the past

1 female can produce 1000 offspring in her lifetime

If one offspring is resistant to insecticide then with this high reproduction rate, an immune population will develop.

Mosquitoes became resistant to DDT

Global eradication of Smallpox

• First important disease to be eradicated
• No evidence that the virus remains latent in the human body after recovery
• Small pox is not as infectious as influenza or measles
• No natural animal reservoir
• Because of these factors - small pox was eliminated from North America and most of Europe by 1950
• Annual cost of vaccination plus that of maintaining quarantine barriers was calculated at over $1 billion. (financial burden on wealthier countries)
• WHO smallpox eradication programme
• The people leading the programme spent time in the field to gain respect from the staff members who did the actual work of eradication
• Difficult countries: India and Ethiopia.
• India: 1962, government launched small pox eradication campaign with mass vaccinations, but by 1970 it was clear this failed. Main reason: the heat sensitive liquid vaccine was often inactive by the time it was administered. Tried different strategy: "surveillance and containment". Had people in the field vaccinating people that surrounded an outbreak. Rewards for notification of small pox in an area and watchmen around 24/7. Health workers took search weeks in every village. Last case was reported in May, 1975

Ethiopia

• Began an intensified smallpox eradication campaign in 1971.
• Major obstacles, making eradication difficult, were obvious. The country was large, mostly mountainous, and 90,070 of the 28 million inhabitants were dispersed in rural areas.
• Communications were always poor or nonexistent in the rainy season.
• Health personnel were few in number and concentrated in urban areas.
• Addition of 4-wheel dive vehicles and eventually helicopters
• WHO funding
• Round the clock watchmen
• Last case: August 1976

• Needed to prove global eradication. Reward for anyone who finds a case.
• 1977 - global eradication seemed imminent
• Need to research a lot into a disease before trying to eradicate it as it may be able to mutate and create a new strain
• Smallpox was easily detectable even by uneducated villagers
• There is no such feasibility with any other disease

• 18th century: Societies not able to sustain population movement of people fleeing war
• 19th century: european conciousness of population displacement increased.
• 20th century: international responces to mass population displacement
• 1921: international commities of the red cross - petitioned the league of nations to provide support for russias that had been displaced (first international move in dealing with population displacement)
• UNHCR established- 1951- respond to mass population displacement
• Refugee: displaced person - outside the country of nationality, crossed an international border
• Internally displaced people are the problem of the country they are in, which may just cause more problems
• 1970s: pick up in refugees in Asia due to veitnam war and cambodian genocide causing people to move to thailand (around 17 million a year)

Severe epidemiological consequences

• Overcrowding
• Dependence on food aid
• Rise in sexual attacks
• Unsanitary conditions
• Population mixing

Relief camps

• Enclosed area for refugees and those assisting them (UNHCR, 2000)
• Temporary 
• Food aid may not be sufficient 
• Militarization of camps - camps become infiltrated with soliders, they have power over the food coming in
• Most mortality in the early stages of a displacement event
• Progressive increase in mortality after the opening of the relief camp - nutrional deficiencies - av calories per day 400, meant to be 900 (Thailand)
• Measles, Cholera, Pneumonia

Responses

• A health information system for nutrition monitoring and disease surveillance
• Immunization against measles and other WHO target diseases
• Targeting of women and child health

Cholera

• Genocide: Destruction of a nation or ethnic group
• Annually, mortality resulting from genocine is higher than mortality is higher than that of malaria and HIV/AIDS
• Rwanda - Central africa
• Tensions between tribes in Rwanda resulting in genocide
• Majority of refugees feld to the Democratic Republic of Congo (1.2 million).
• Goma - mortality was almost unpesidented in the camps - not prepared
• In one month in Goma - 500,000-800,000 refugees, 6-10% dying within a month
• Main problem was diarrhoeal diseases (cholera)
• 6 days into the refugee movement there was a case of cholera and within a month there were 62,000 cases of diarrhoeal diseases most of which are cholera
• Lake responsible
• Vaccination would not have helped because the spread was so quick

• No legal meaning
• Removal of people from areas (normally religious). Removing rather than distruction - but really sometimes the removal is violent and could be called genocide

Ethnic cleansing and the kosovo war (1998-99)

• March 1998: Conflict between the Kosovo Liberation Army (KLA) and the Federal Republic of Yugoslavia (FRY)
• Targetting of civilian settlements causing mass population movement
• West Kosovo disease found: Tularemia. Reservoirs include rabbits, hares and rodents
• Transmission occurs via skin contact with the infected animals or contaminated water
• Was thought that Yugoslavia deliberatly spread the disease into West Kosovo as a war tactic
• Most probably: due to environmental changes such as disrupted agricultural environment, deserted homes and unprotected food in Kosovo causing a rapid increase in rodent populations

Public health impact of Rwandan refugee crisis: what happened in Goma, Zaire, in July 1994?

• 50,000 refugees died in a month
• In April, 1994, the president of Burundi and Rwanda were killed in an airplane crash. This lead to civil disturbance thoughout Rwanda cause many people to flee to Goma, Zaire (1.2 million). 
• The arrival of such an enormous number of dependent refugees durig a sort period overwhelmed the relief organisations 
• The refugee camps were located on hard volcanic rock so graves could not be dug and bodies were just left beside roads
• Surveys were taken on: presence or absence of adult men in the household, access to food rations and adequacy of shelter - in the camps
• 23% of children aged 6-59 months had acute protein-energy malnutition
• Water was taken to drink from the lake too much to chlorinate it everytime

• Not extinct as there are a couple of laboratories with the small pox virus for research
• 1796 - vaccine invented
• In the 1900's small pox was endemic in most countries except for countries such as australia 
• Vaccination raises endemic threshold for small pox

4 main phases of small pox eradication

• 1. Preparatory phase
• Epidemiological assessment and education programmes for health personal and local population
• 2.Attack phase
• Systematic mass vaccination and surveillance
• 3. Consolidation phase
• Maintenance vaccination of newborns, immigrants etc.
• 4. Maintenance phase (when there are no cases for more than 2 years)
• Maintenance vaccination and surveillance
• 1980 - WHO annouced the eradication of small pox had been achieved

• Viral diseases
• Single exposure - life-long immunity
• 90-95% of infections are sub-clinical

Campaign strategies

• High immunization coverage with oral polio vaccine
• Disease surveillance
• Problem: most cases are sub-clinical

Success?

• 1988 - start of campaign
• Decrease in disease from here
• Endemic activity decreased - by 2003 only endemic in India and parts of Africa have cases
• In 2003 it went wrong - Northern nigeria they suspended the vaccine (was endemic here) as there were rumours that they were just trying to sterilize the popualtion. The disease spread out from nigeria around Africa 
• 2005 - spread to Yemen and Indonisia 
• 2015 - endemic transmission in afganistan and pakistan

So close: remaining challenges to eradicating polio

• Global Polio Eradication Initiative, launched in 1988
• Africa has been polio-free for more than 18 months
• Polio cases have decreased by 99.98% since 1988
• In areas where water quality, sanitation and hygiene are poor, ten or more doses of the vaccine are required
• Progress was slow and the number of cases reported in 2010 was higher than in 2000
• Conflict has made it difficult in Afghanistan, Pakistana and Nigera to access children for the polio vaccination
• In Pakistan the Taliban has banned polio vaccination
• As recently as January 13, 2016, a suicide bomber detonated explosives outside a polio vaccination center in the city of Quetta, killing 15 and wounding 24 people
• Radical political forces in a number of countries have demonstrated that they will put their own agenda ahead of the well-being of children.