Introduction to Global Health and Tropical Medicine
Introduction to Global Health
Global Health introduction
Definition of global health
- Collaborative trans-national research and action for promoting health for all
- Achieving health equity by study, research and practice
Cost effectiveness is a very important aspect of Global Health.
Career in Global Health
- National representative
- Netherlands course in Global Health and Tropical Medicine, 28 months
Determinants of health
Health
- WHO: a state of complete physical, mental and social wellbeing, and not merely the absence of disease or infirmity → practically impossible to achieve
- S. van der Geest: the proper functioning of the body
- M. Hubert: the ability to adept and self-manage
Determinants
- Determinant: a factor that decisively affects the nature or outcome of something
Models of determinants of health are:
- Lalonde framework: assumes no interaction between determinants of health
- Skolnik model: more complex model used in this course
Different determinants influence each other. Health care has a relatively low impact on health status. Social determinants of health are particularly important for the wellbeing of patients.
According to epidemiologists Wilkinson and Pickett, “equality” in itself is a determinant of health.
Long and healthy life is a precondition for development, which stimulates participation in the society. Generally, high income relates to a good health status. Therefore, economic development is a precondition for a long and healthy life.
However, the Blue Zone Project shows that there are additional factors such as social cohesion and lack of stress that stimulate a long and healthy life.
Health indicators
Indicators
Indicator: measure that tells something about the state or level of something. Health indicators are often ratios or rates with a numerator and a denominator.
- Ratio: compares two measures of the same dimension
- Rates: compares two measures of different types
Key Health Status indicators:
- Life expectancy at birth: the number of years a newborn baby would live if subjected to the present mortality risks prevailing for each age group in the population
- Child mortality: low income countries have a high child mortality under 5 years due to malnutrition
- Categories: perinatal, neonatal, postneonatal, infant, under 5 years
- Infant mortality rate: the number of deaths of infants under age 1 per 1000 live births in a given year
- Neonatal mortality rate: the number of deaths to infants under 28 days in a given year per 1000 live births in that year
- Under-5 mortality rate: the probability that a newborn baby will die before reaching age 5, expressed as a number per 1000 live births
- Maternal mortality ratio: the number of maternal deaths per 100.000 live births
- Maternal mortality rate: the number of maternal deaths per woman of reproductive age per time period
- DALY: disability adjusted live year, YLD + YLL
- YLD: years of life lost due to disability → number of incident cases, average duration, how severe the disability is
- YLL: years of life lost due to death → number of deaths and age of death
- HALE:
Global Health: Neglected Tropical Diseases
RC NTDs – an introduction
Definition
NTD is a relatively new identity. The term NTD was first used in 2003. It was coined by Peter Hotez and colleagues to counterbalance the attention given to HIV/AIDS, tuberculosis and malaria.
The list
There are 20 NTDs on the list, even though different sources give different numbers of NTDs. This is relevant because it is very difficult for diseases not on the list to find money for research and therapy. The 3 most recent diseases listed by the WHO are mycetoma, scabies and snakebites. Snakebites is the only non-infectious disease on the list.
Several NTDs are not restricted to the tropics, such as:
- Snakebites
- Scabies
- Rabies
- Echinococcosis
- Leprosy
NTDs which are restricted to the tropics because of climate are:
- African Sleeping Sickness
- Chagas
- Onchocerciasis
- Schistosomiasis
- Dengue
- Buruli ulcer
- Leishmaniasis
- Soil-transmitted helminthiases
- Mycetoma
- Yaws
- Lymphatic filariasis
These diseases all need a vector, which can only survive in tropical areas.
Causes
NTDs occur in the most poor communities of the world:
- Common, poverty related, risk factors
- Occur in 149 endemic countries
- People are infected with at least one NTD
Often, if one has 1 NTD, they have many NTDs because the risk factors are the same. The advantage of this is that multiple diseases can be controlled at the same time.
Microorganisms
NTDs can be caused by:
- Bacteria
- Buruli ulcer
- Leprosy
- Trachoma
- Yaws
- Viruses: the rarest
- Rabies
- Dengue and chikungunya
- Parasites
- Protozoa
- Chagas disease
- Leishmaniasis
- Human African Trypanosomiasis
- Helminths: occur the most often
- Cysticercosis
- Guinea-worm disease
- Echinococcosis
- Foodborne trematodiases
- Lymphatic filariasis
- Soil-transmitted helminthiases
- Schistosomiasis
- River blindness
- Protozoa
There is no existing vaccine against helminths.
Epidemiology
Most NTDs have a high morbidity and disability, while the mortality is low → many NTDs are chronic and don’t immediately cause death. This is why the diseases are so often neglected. NTDs promote poverty and interfere with economic development.
Prevalence
The most prevalent NTDs are the soil-transmitted helminths (STH):
- Roundworms
- Whipworms
- Hookworms
1,5 billion people have a STH. The NTD intestinal nematodes (STH) costs the highest burden of disease around the world, because so many people are infected with them.
Fatality
3 NTDs with the highest case fatality rate are:
- Rabies
- 99% fatality
- African trypanosomiasis
- 100% fatality
- Visceral leishmania
In case of these diseases, as soon as there are symptoms and there is no treatment, the patient dies.
Blindness
2 NTDs which cause blindness are:
- Onchocerciasis
- Trachoma
- Causes infections of the eye
Stigma
3 NTDs which are a stigma, causing high social-economic impact, are:
- Lymphatic filariasis
- Buruli ulcer
- Yaws
Treatment and intervention
Multiple NTDs have a common treatment and share a similar way of intervention:
- MDA
- Vector control
- Safe water, sanitation and hygiene
For example, by deworming communities and schools, the burden of helminthic diseases can
.....read more Global Health: Non-communicable diseases and the "Big 3"
RC HIV control in Africa
Epidemiology of HIV in Africa
37,7 million people are living with HIV globally, of which 25,4 million live in Africa. Especially in southern African countries, the prevalence of HIV is very high:
- Zambia
- Botswana
- Namibia
- South Africa
- Eswatini/Swaziland
- Mozambique
- Zimbabwe
Although the number of new infections is declining worldwide, the majority of new infections occur in Africa. These infections mainly (>60%) occur among women, while in Western Countries mainly men are affected. In general, the transmission rate from men to women is higher, women in Sub-Saharan Africa aren’t in the position to negotiate about safe sex and are often involved with older men.
Subtypes
There are different HIV subtypes circulating. In Africa, HIV-1 subtype C is most common, while in Western Countries most infections are HIV-1 subtype B. This means that research mainly is done for HIV-1 subtype B, while in Africa medication for subtype C is necessary. Subtype C and D also appear more pathologic than subtype B.
Antiretroviral treatment and HIV control in Africa
In 1996, a life-saving combination triple therapy was found. This therapy was very effective in suppressing the virus. However, ART (antiretroviral treatment) was hardly covered in the African region. This was the cause of many protests → ART for Africa. This led to an international response to AIDS:
- 2000 Durban conference “Breaking the Silence” → the first conference held in an African country
- It finally became clear how big the problem was
- 2001 UN Declaration of Commitment on HIV/AIDS
- Made sure that people who needed it, would get their medication
- 2002 Global Fund to Fight AIDS, TB and Malaria (GFATM)
- A lot of money was necessary to get the drugs where they were needed
- 2003 PEPFAR
- Emergency plan for AIDS relief
Meanwhile, UNAIDS was in discussion with several pharmaceutical companies to reduce the price of ART’s → the price reduced from $10.000/year to $900/year.
However, around 2004, there were challenges for ART access in Africa:
- Shortfalls in health services
- Lack of knowledge about treatment
- Making decisions about newer treatments
- Risk of resistance to ART
Nevertheless, after 2004 the number of people on ART started rising and is now similar to the numbers in Western Countries. This led to a huge increase in life expectancy → a 25-year-gap. The availability of ART also resulted in less people getting infected with HIV.
WHO guidelines
In 2002, the WHO made guidelines for when to start ART in LMIC. These guidelines evolved over time:
- 2002: ART for everybody with a CD4-cell count of <200
- Normal: CD4-cell count is >500
- 2006: ART for everybody with a CD4-cell count of <200 or with a CD4-cell count <350 and TB
- The treatment started being given earlier and earlier
In 2015, the START and TEMPRANO trials looked into when ART should be started. It appeared that when ART was initiated immediately, the CD4-cell
.....read more Global Health: Nutrition, culture & technology
Malnutrition
Malnutrition
Nutrition is part of a balance:
- Undernutrition: immunosuppression and susceptibility to infection
- Optimal nutrition: normal immune function
- Overnutrition: immune-activation and susceptibility to inflammatory diseases
There is malnutrition in case of undernutrition and overnutrition.
Undernutrition and overnutrition
Undernutrition is an insufficient intake of macro- or micronutrients to meet nutritional needs. Macronutrients are proteins and fat, micronutrients are vitamins and minerals. There are 2 types of undernutrition:
- Growth failure
- Micronutrient malnutrition
Overnutrition is an excess amount of energy leading to overweight and possibly chronic disease.
Nutritional transition
Besides a demographic and epidemiologic transition, there also is a nutrition transition. There is interaction between these 3 transitions. Nutrition transition is the pattern from scarcity to over-consumption → a change from an active lifestyle and whole grain foods to a sedentary lifestyle and ready-made convenience foods. A nutritional transition has different stages:
- Paleolithic man/hunter-gatherers
- Settlements begin → famine emerges → high prevalence of undernutrition
- Industrialization → receding famine → slow mortality decline
- Nutrition related noncommunicable diseases predominate
- Desired societal/behavioral change → focus on medical intervention, policy initiatives and behavioral changes
Macronutrient deficiencies
There are different types of macronutrient undernutrition:
- Normal: normal weight and height
- Wasted: thinner than normal
- Stunted: shorter than normal
- Wasted and stunted: thinner and shorter than normal
Wasting is indicative of acute undernutrition, such as in famine or emergencies requiring humanitarian assistance. Stunting is indicative of chronic undernutrition and is common in low income populations in non-emergency cases.
Child undernutrition
- Wasting: extreme thinness → weight for height below -2 SD
- Stunting: extreme shortness → height for age below -2 SD
- Underweight: composite measure of undernutrition capturing thinness and/or shortness → weight for age below -2 SD
Protein energy malnutrition
Protein energy malnutrition, also known as Marasmos, is an extreme protein and energy deficiency. It results in an appearance of skin and bones with little or no subcutaneous fat and a pronounced loss of muscle mass. It can lead to limited brain growth and development. It is a very serious condition of undernutrition.
Protein and vitamin deficiency
Protein and vitamin deficiency, is also known as Kwashiorkor. It can lead to oedema, retention of some subcutaneous fat, red coloring of the hair, apathy and growth retardation. It is a very serious condition of undernutrition.
Micronutrient deficiencies
The 4 most prevalent micronutrient deficiencies are:
- Vitamin A: xerophthalmia/blindness
- Important to mucous membranes → dryness causes temporary night blindness of permanent damage leading to blindness
- Important to immune function: supplementation has resulted in reduced risk of measles and diarrhea
- Dietary sources: liver, yellow/red vegetables
- Iodine: cretnism, goiter
- Needed for thyroid hormones
- Regulates the basal metabolic rate
- Important to early development of the fetus
- Insufficient iodine → overactive pituitary gland → TSH production → thyroid gland produces more TH → increase in activity and size of the thyroid gland
- Dietary sources: sea foods, iodized salt
- Needed for thyroid hormones
- Iron: anemia
- Necessary component of hemoglobin
- Deficiencies related
Add new contribution