MICRO: Global health priorities and brain worms Flashcards

1
Q

What did the Alma Ata Declaration 1978 reinstate?

A

Reinstated the definition of health: a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity

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2
Q

What two factors does DALY encompass?

A

Morbidity and mortality

DALY = YLL + YLD

  • YLL= No of deaths * standard life expectancy at time of death
  • YLD=No of incident cases * disability weight * average duration of case
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3
Q

What does 1 DALY mean?

A

1 DALY = 1 lost year of healthy life lost

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4
Q

What is a QALY?

A
  • Measure of disease burden
  • Includes both quantity and quality of life lived
  • Used in assessing the value of a medical intervention
  • Based upon the number of years of life that would be added by the intervention
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5
Q

What is 1 QALY?

A

A year in the hypothetical state of “perfect health” is worth 1 QALY.

Being deceased is worth 0 QALYs.

Other health states fall between 0 to 1

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6
Q

How are standard and new treatments comapred in terms of benefit to the quality of life?

A

Patients receiving standard treatment will live for 1 year and quality of life will be 0.4 (0 = worst possible health/death, 1= perfect health)

Patients receiving new drug will live for 1 year 3 months (1.25 years), with a quality of life of 0.6.

The new treatment is compared with standard care in terms of the QALYs gained:

  • Standard treatment: 1 (year’s extra life) x 0.4 = 0.4 QALY
  • New treatment: 1.25 (1 year, 3 months extra life) x 0.6 = 0.75 QALY

Therefore, the new treatment leads to 0.35 additional QALYs (that is: 0.75 -0.4 QALY = 0.35 QALYs).

The cost of the new drug is assumed to be $10,000, standard treatment costs $3000.

The difference in treatment costs ($7000) is divided by the QALYs gained (0.35) to calculate the cost per QALY. The new treatment would cost $20,000 per QALY.

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7
Q

Why is QALY debated?

A
  • What is perfect health? Not patient-centric
  • There may be a health state worse than death
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8
Q

Case:

  • 42 year old man originally from Ecuador
  • 1 month occipital headache
  • 3 generalised tonic-clonic seizures, spontaneous recovery
  • 1 previous seizure in Ecuador 1985, no medications
  • works as a cleaner
  • lives with wife & 3 sons, 1 of whom has epilepsy (age 19)
  • 5 cigarettes/week, occasional alcohol

Cystic lesion seen below.

Calcification is also seen (reverse) in the brain.

A

Cyst + calcification = Taenia solium cysticercosis

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9
Q

What is the source of Taenia solium cysticercosis?

A

Pork tapeworm larvae - common in all non-Muslim developing countries

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10
Q

What is Taenia solium cysticercosis often misdiagnosed as?

A

Commonest cause of adult-onset epilepsy in many countries, causes 20-30% of adult onset epilepsy in Peru

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11
Q

What two tapeworms can cause intestinal infection/taeniasis in humans? How severe is tineasis?

A
  • Intestinal infection with adult stage of large tapeworms
    • T. solium
    • T. saginata
  • Generally non-fatal - usually asymptomatic, may live for many years and grow up to 30m.
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12
Q

What tapeworm causes cysticercosis? How severe is the infection?

A
  • Tissue infection with larval stage of T. solium

Serious disease that usually involves the CNS. Infection may be fatal

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13
Q

How do pig get infected with porcine cysticercosis? What type of tinea solerium infection is caused by eating infected under-cooked pork?

A

Pig infection by:

  • pigs ingest tapeworm eggs in human faeces
  • parasites migrate to tissues & encyst - measly pork

Humans eating pigs only causes intestinal tapeworms.

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14
Q

Describe the life cycle of taenia solium infections.

A

It is caught from other humans (faeces/GI spread) and cysticercosis is a dead end for the spread of the disease

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15
Q

What is the route of infection for human cysticercosis?

A

Ingestion of tapeworm eggs - in food contamintated with faeces so vegetarians and meat eaters can all be affected

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16
Q

What sites are infected by cysticercosis?

A

ALL tissues in the body canbe affecte (incl. muscle and heart)

17
Q
A

Still a possible cause if it is endemic in the area where you live despite you being vegan/vegetarian/never eating pork

18
Q

What are the clinical features of neurocysticercosis?

A

Brain cysticerci are the most frequent cause of symptomatic disease

Clinical features depend on the immune response, number & site of cysts e.g.

  • 65% epilepsy
  • 24% raised intra-cranial pressure
  • 22% headache
  • 14% altered mental staten
  • also stroke, blindness, spinal disease
19
Q

How do neurocysticercosis parasites surive in the body?

A

Evade and suppress inflammation by…

  • sequestration/fibrous encapsulation
  • concomitant immunity
  • molecular mimicry/masking
  • modulation of host immunity
20
Q

What is likley to be happening if you get symptoms with neurocysticercosis?

A
  • Usually, living cysts are asymptomatic
  • Symptoms mark cyst degeneration
  • Associated with eosinophilic cellular influx
21
Q

What is the management of neurocysticercosis?

A

Anticonvulsant therapy

Ventriculo-peritoneal shunt (if hydrocephalus occurs)

Cestocidal drugs (albendazole or praziquantel)

  • accelerate disappearance of viable cysticerci
  • cause transient inflammation around viable cysticerci
  • randomised trials suggest clinical benefit

Steroids for inflammation around dying cysts

  • partial effect for cyst degeneration/cestocidal therapy
  • inadequate for: chronic granulomatous inflammation
  • heavy infections – cestocidal therapy without steroids may be fatal
22
Q

What caution should be taken when using anti-parasitic drugs for severe cysticercosis?

A

There may be a triansient exacerbation - steroids should be added in severe cases to reduce inflammation (cestocidal therapy without steroids may be fatal)

23
Q

What is a simple intervention used to reduce cysticercosis in developing countries?

A

Rice growth - pigs will go into these instead of eating human faeces