disease dilemmas 1

Question 1

types of disease and diffusion

Answer 1

• communicable: spreadable from host to host. Non-communicable: disease that cannot be spread between people.
• infectious: a disesase caused by a pathogen e.g. virus. Contagious: spread from person to person. Zoonotic: diseases passed from animals to human.
• expansion d: has a source and spreads outwards to new areas. Relocation d: a disease that leaves the area or origin and moves into new areas.
• contagious d: describes the spread of disease through direct contact with a carrier. Hierarchical: spreads through an orderd sequence of places usually from largest centres to smallest.

Question 2

hagerstrand’s diffusion model

Answer 2

• applied to contagious diffusion of disease: 3 concepts: the neighbourhood effect, s shaped curve of infections and physical barriers to diffusion.
  1- neighbourhood effect: probability of contact between a carrier and non-carrier is detirmned by the no.of peopleliving in each 5x5m sq. High pop density: more diffusion.
  2 - s strand model:1 - primary step: disease is localised, slow increase in cases. 2 - expansion step: no.of cases increases rapidly. 3 - condensation step: rate of diffusion slows due to barriers both socio economic and physical. 4 - saturation step: no.of new case flattens out as herd immunity develops.
  3 - progress and diffusion of disease may be interrupted by physical barriers e.g. oceans, mountains, borders, distance.

Question 3

factors affecting malaria

Answer 3

Physical barier: 1 - rainfall: malaria prevelant with >1000mm of rain, female anopheles lay eggs in waterthey hatch into larvae. Temp: prevelant in 18-40C, larvae develops quick when warm and parasite completes lifecycle. Relative humiduty: When monthly RH is >60%, mosquitos better survive. relief: high altitudes are too cold for mosquitos. Monsoon: WHen rainy season ends: stagnant pools of water exist this is where mosquitos lay eggs.

Human barriers: poverty: stagnant pools of water from rubbish dumps create breeding grounds. Irrigation canals: irrigation canals built for crops: more stagnant water and breeding. Harvesting after dark: lots of harvesting done after dark, many sleep in the fields wiht no mosquito nets. Building dams: grand ehtiopian renaissance dam built in 2020: stagnant pool of water

Question 4

impacts of climate change on diffusion

Answer 4

Malaria; bacteria thrive in warm conditions as it is found in water algae and multiplies. Mosquitos are on the move: global emissions make everywhere warmer so mosquitos move further north and south. Changing habits: more animal to human transmissionsas animals move more with changing climate. Temp increase of 2-3C could cause 3-5% malaia increase. In Ethiopia a 1C temp rise could lead to 3m more cases in >15s.

Anthrax: In Siberia in permafrost, originally from reindeer carcass in PF> Rising temps = ice melt and bacteria is active. Anthrax outbreak 2016: 1st in region for 75 yrs, 2300 reindeer dies and 1 12 yr old boy died. Ancient viruses found in tibetian glacier: scientist discovered 15,000 yr old viruses over 33 found and 28 unknown.

Question 5

cholera in haiti

Answer 5

• cholera is a waterborne disease caused by contaminated water, it is infectous, communicable and contagious.
  came to cholera via:
• relocation: UN worker from Nepal arrives in Oct with cholera bacteria, trained in Katchmndu which had had an outbreak.
• contagious: cholera is contagious and spreads from person to person which is why it spreads so rapidly .
• expansion: Nov 19th cholera spread to all 10 departments of haiti, more than 6% of haitians had acquired the disease.
• hierarchical: nov 9th: disease spread from ourlying areas to capital, first infected in P-A-P were found to have travelled from the Aribonite area: disease had travelled via the river.

700,000 infected(7% of pop). 10,000 deaths, distrust of united nations

Question 6

factors affecting the spread of cholera

Answer 6

Human: First outbreak in 100 years so low immuniy. Population had never experienced an outbreak so was unaware of the disease. It started in rural Haiti, water sources and sanitation were well below average for the caribbean, only 33% had access to treated tap water. EQ meant a low shorage of health care pesonal they were strained from EQ. NO runnisn water in camps, water delivered from red cross was not safe. Disease came from Nepalese peacekeeping troops. Movement of perople spiked cholera cases. Pre EQ Haiti was poorest nation in west hemispgere: in P-A-P 86% lived in slums

Physical: Heavy rains in the week after outbreak flooded the Aribonite river with raw sewage. 90% of homes destroyed in EQ: 1.5m forced into slums. After EQ Haiti experienced warm temps and high rainfall creating optimal conditions. After outbreak hurricane tomas hit, swelling rivers and triggered floods.

Question 7

responses to cholera outbreak

Answer 7

National repsonse:
- ministry of public health and population (MSPP) and centre for disease control and prevention (CDC): worked in 5 areas, decrease deaths, work for water distribution, focus on science and research, spread messages on oral rehydration.
International response:
- UN, WHO &UNICEF: Nov 2010:Un launched national sanitation campaign: drink safe water, wash hands, use latrines, cook food well, clean up. WHO: mapped cholera case. Un supported MSPP for vaccination programe aimed 400,000 vaccinated. worked with others for national cholera elimination plan 2013-2022: improve water access and sanitation and healthcare.
- MSF: Recruited new staff, worked in 26 hospitals, treated 350,000 patients, 16,000 surgeries, treated 60% of cholera cases.
- Oxfam: provided water, built 2500 latrines, 79 million gallons of water, devoted $19.5 million to affected areas. UK gov: provided £2m in funding, set up 12 major cholera treatment centres.