Case Study of a Face Eating Parasite

After marking hundreds essays about HIV over the summer, the typical case study of an infectious disease, and becoming increasingly bored of the lack of variation when there are so many other important infectious diseases in the world I decided it was time to introduce my students to something new: a FACE EATING parasite!

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Leishmanisis - Case Study of an Infectious/Communicable Disease

GLOBAL DISTRIBUTION

o More than 90% of global cases of visceral leishmaniasis occur in only 6 countries including India, Sudan and Brazil.

o Cutaneous leshmaniasis is more widely spread in 3 main epidemiological regions including South America and the Mediterranean basin with Sudan, Afghanistan and Brazil having some of the highest rates.




IMPACTS

HEALTH
o Parasitic disease caused by the leishmania parasite and transmitted by the female phlebotomine sand fly; associated with malnutrition, famine and weak immune systems

o Cutaneous and mucocutaneous leishmaniasis affect the skin and mucous membranes of the mouth and nose leading to disfiguring scars and deformities

o Visceral leishmaniasis causes a swollen liver and spleen and can kill without treatment

o Health impact has been grossly underestimated until recently, now thought to be second to Malaria

o Could be due to a high morbidity and low mortality, although some epidemics of VL have high case-fatality rates e.g. 100 000 deaths caused in Sudan between 1984-94

o 70 000 deaths per year from VL

o HIV and Leishmaniasis are mutually reinforcing

o Leishmaniasis stimulates the HIV virus to replicate and people with HIV are up to 2000 times more likely to catch leishmaniasis because their immune system is supressed




ECONOMIC DEVELOPMENT
o Affects the ‘poorest of the poor’ making it impossible to earn and thus affecting their whole family

o Cost of treatment in Bangladesh estimated to be 1.2x annual per capita income

o People have to sell or rent their assets or take loans to pay medical bills

o Delays socioeconomic development

o For example epidemics of the disease have delayed the implementation of development projects in the Amazon basin as money is needed for treatment instead

o Puts strain on the economic productivity of a country’s workforce as people are unable to work




LIFESTYLE
o Social stigma due to disfiguring scars can cause anxiety, depression and quality of life

o Associated with illiteracy and low levels of education as people don’t know how to avoid it

o People don’t understand the disease so patients are victimised and isolated, especially those with active lesions, e.g. Afghan refugees have become known for their scars

o HIV-leishmaniasis sufferers can experience even more physical and psychological pain



o Particularly affects women and associated with gender discrimination

o Cultural expectations of women mean that any disability may cause abandonment by their husbands, in societies where women are very dependent.

o Most severely affected group children under 15, which could cause bullying and children to become a burden on the family




Discussion point: Which form of the disease do you think is the worst and why?

Tackling Essay Questions at AS

Essay questions more than any other are designed to test your ability to USE and APPLY what you have learnt to the question, not simply regurgitate it and give a long description with no discussion or assessment.

Remember that these questions are level marked, each level shows a higher level of understanding, knowledge and ability than the previous one. Let’s look at this more closely with an example from the AQA AS topic 'Health Issues'…

“An infectious disease has a greater impact on economic development than a non-communicable disease.” To what extent do you agree with this view? (15 marks)

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