Environment and the Brain 2 Flashcards
Name four countries where malaria is particularly common. (4)
- Nigeria
- Democratic republic of the Congo
- Tanzania
- Niger
***These are all African countries
Give two social consequences of Malaria. (2)
- Costs a lot of money to prevent and treat
- Results in huge economic losses
Describe the general prognosis of malaria. (2)
- Many people still die from it but is not always fatal
- 80% of deaths are children under 5 years old
True or false? Explain your answer if appropriate. (1)
Malaria remains a huge public health challenge, with some countries still experiencing endemic levels of the disease.
True
Name the vector which passes malaria between humans. (1)
Female Anopheles mosquito
Give five types of malaria parasite. (5)
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
Which malaria parasite is responsible for the majority of malaria deaths worldwide? (1)
Plasmodium falciparum
The five types of malaria parasite are all which type of parasite? (1)
Protozoa
Describe the malaria illness and its timecourse associated with Plasmodium vivax and Plasmodium ovale parasites. (1)
Lie dormant in liver and cause malaria relapses months or years after initial infection
Which malaria parasite can cause lifelong, chronic infection if it is left untreated? (1)
Plasmodium malariae
State which organisms are mainly affected by Plasmodium knowlesi. (2)
Mainly monkeys in South-East Asia
however can sometimes cause severe/fatal illness in humans
Describe the life-cycle of malaria, as occurs in humans (do not describe the mosquito parts). (8)
- Mosquito transmits motile sporozoite to humans
- Sporozoite travels through blood to liver cells
- Sporozoite reproduces asexually in liver (schizogony)
- This produces thousands of merozoites
- Merozoites infect red blood cells
- And further divide asexually, to develop into ring forms, trophozoites, and schizonts, which burst from blood vessels
- Merozoites can also develop into precursors of gametes
- Gametes taken up by mosquito bite
Describe the life-cycle of malaria, as occurs in mosquitoes (do not describe the human parts). (5)
- Mosquito bites infected human and takes up gametocytes
- Gametocytes mature in mosquito gut
- Male and female gametocytes fuse and form ookinete
- Ookinetes develop into new sporozoites that migrate to salivary glands
- Sporozoites transmitted to humans through bite
Name the definitive host for Malaria. (1)
Mosquito
Name the intermediate host for malaria. (1)
Humans
Describe the small life-cycle of malaria occurring in red blood cells of humans. (4)
- Merozoites infect red blood cells
- Divide asexually to produce ring forms, trophozoites, and schizonts
- RBCs burst and release parasites
- Which can go on to infect more RBCs
Give three general consequences of malaria parasites bursting from and destroying red blood cells in malaria infection. (3)
- Damage to blood vessels
- Damage to organs
- Allows infection to continue proliferating
What is the most common clinical presentation of malaria in humans? (1)
Most infections are asymptomatic
(However a small percentage of individuals develop severe malaria)
Give a life-threatening complication of severe malaria, which occurs in 575,000 children annually in Africa. (1)
What percentage of people with this complication die from it? (1)
What consequence can it cause in survivors? (1)
Cerebral malaria
20% die from it
Survivors can have neurological impairment
Cerebral malaria, a complication of severe malaria, can develop at any age.
Which age group is the most at risk? (1)
Children under 5 years old
Give two groups of people particularly at risk for cerebral malaria. (2)
- Young children who haven’t yet developed immunity
- People from other countries who have not been exposed to malaria
(People with low immunity to the disease)
Describe the typical timecourse of classic malaria. (2)
Lasts 6-10hrs
However can come and go in waves for 12-48hrs as new parasites are released into the bloodstream.
Name the three symptomatic stages of classic malaria. (3)
Cold stage
Hot stage
Sweating stage
Briefly describe the ‘cold stage’ of classic malaria. (1)
Sensation of cold and shivering
Give four symptoms which may be experienced in the ‘hot stage’ of classic malaria. (4)
- Fever
- Headaches
- Vomiting
- Seizures in young children
With classical malaria, it is possible to get relapses years later.
Why is this possible? (1)
Due to dormant parasites in the liver
Give nine signs/symptoms that can be seen in severe malaria. (9)
- Severe anaemia
- Immune responses throughout the body
- Haemoglobin in urine
- Acute kidney injury
- Acute respiratory distress syndrome
- Abnormalities in blood coagulation (DIC)
- Cardiovascular collapse
- Metabolic acidosis
- Cerebral malaria
In severe malaria, immune responses are seen in many areas of the body.
Give two reasons why a large, widespread inflammatory response is seen. (2)
- Due to parasites infecting the body and bloodstream
- Due to destruction of red blood cells
Why is anaemia seen in severe malaria? (1)
Due to destruction of red blood cells
Why is acute respiratory distress syndrome seen in malaria? (1)
Due to inflammatory response in the lungs
Finish the sentence, regarding severe malaria. (1)
Severe malaria may be associated with hyperparasitaemia, which is where ……………………………
malaria parasites infect more than 5% of the total red blood cells
When is cerebral malaria diagnosed? (1)
If the patient is in a coma
Apart from coma, give another symptom/sign of cerebral malaria. (1)
Seizures
Briefly describe three brain pathologies that are seen in cerebral malaria. (3)
- Obstruction of microvasculature
- Neuroinflammation
- Loss of BBB integrity
Describe why the brain microvasculature becomes blocked in cerebral malaria. (2)
Give two consequences of this. (2)
- Adhesion/sequestration of plasmodium-infected RBCs to endothelial cells
- Platelets can then also adhere to contribute to blockage
CONSEQUENCES:
hypoxia
oedema
Compromised integrity of active endothelial cells leads the BBB to become permeable in cerebral malaria.
Give three possible consequences of this. (3)
- Loss of brain homeostasis
- Oedema
- Small haemorrhagic events
Suggest two mechanisms by which BBB integrity may be disrupted in malaria. (2)
- Infected RBCs which stick to endothelial cells may damage them
- Neuroinflammation and pro-inflammatory cytokines damage BBB
Suggest reasons why neuroinflammation may occur in malaria. (3)
- Hypoxia leads to neuronal damage
- Plasmodium parasites activate immune response in blood vessels
- BBB integrity compromised which leads to foreign cells/molecules in brain
True or false? Explain your answer if appropriate. (1)
Brain changes seen in cerebral malaria may also be seen in malaria patients who do not meet the criteria for cerebral malaria, some of which may even have uncomplicated malaria.
True - seen in patients with severe non-cerebral malaria and also uncomplicated malaria
Give a brain change which may be seen in patients with non-cerebral malaria. (1)
Oedema
Give a blood marker indicating brain damage, which may be seen in people with non-cerebral malaria. (1)
What does this marker indicate? (2)
S100B
Glial marker
which may also indicate BBB breakdown
Give five post-malaria neurological sequelae which may affect patients. (5)
- Long-term cognitive deficits
- Epilepsy
- Impaired hearing
- Sensory disorders
- Motor weakness
True or false? Explain your answer if appropriate. (1)
In malaria, the Plasmodium parasite is able to cross the BBB and directly activate the immune response, causing neuroinflammation.
False - the parasite itself does not get into the brain, however damages the brain through the cerebral vasculature and can cause small stroke-like events
Give three general treatment approaches to malaria. (3)
- Prevention
- Anti-malaria drugs (both as prevention and treatment)
- Vaccines
Give four general prevention strategies for malaria. (4)
- Mosquito nets
- Repellents
- Removing stagnant water
- Long-sleeved clothes
Give two malaria vaccines which may be used to treat/prevent malaria. (2)
Give the current status of these vaccines. (2)
RTS,S/AS01 - already rolled out but more demand than supply
R21 - recently approved but not yet rolled out
There are 2 new vaccines being rolled out for malaria.
Which malaria parasite are both of these vaccines effective against? (1)
Plasmodium falciparum
True or false? Explain your answer if appropriate. (1)
New vaccines against malaria have been proven to be safe and effective for adults, but not children in clinical trials.
False - they have proved safe and effective for children in clinical trials
Which is the most common malaria parasite? (1)
Plasmodium falciparum
What is the ‘scientific’ name of the pork tapeworm? (1)
What type of parasite is this? (1)
Taenia solium
Helminth
Describe the lifecycle of Taenia solium. (7)
- Eggs (or gravid proglottids) passed into environment via faeces of infected human
- Cattle and pigs ingest eggs from contaminated soil or vegetation
- Oncospheres (which were contained in eggs) hatch and get into circulation by penetrating the wall of the digestive system
- Oncospheres travel to muscle tissue where they form cysticerci (cysts)
- Humans become infected by eating raw/undercooked meat
- Immature form attaches to human intestine
- Worm matures and becomes an adult within the small intestine
***Tapeworm produces eggs while in the intestine which are released via faeces
Name the definitive hosts for Taenia solium. (1)
Humans
Name the intermediate hosts for Taenia solium. (1)
Pigs
Name the main effect of Taenia solium on the human brain. (1)
Neurocysticercosis
Taenia solium can cause neurocysticercosis in humans.
What is neurocysticercosis? (1)
Give two symptoms. (2)
Cysts in the brain
- Headaches
- Seizures