malaria ph exam 3

malaria burden by the numbers

2023 263 million cases, 579,000 deaths

WHO african region is disproportionately affected

• 94% of malaria case

• 95% malaria deaths

what countries had that highest burden

nigeria, DRC, uganda, ethiopia, mozambique

who is the most typical person affected

child in sub-saharan africa during 2nd year of life

children can be re-infected why.. how

• children get up to 1 infective bite per night

• develop as many as 8 episodes of symptomatic malaria per year

• more time outside, kids don’t swat away, closer to ground

repeated infection will result in development of parial immunity

• after 5th bday, immunity will protect them from severe disease but may still develop uncomplicated malaria

malaria etiology

has 5 parasite species

falciparum parasite

• most prevalent malaria on Africa continent

• responsible for most malaria deaths globally

trophozoites parasite

• dominant malaria parasite outside of sub-saharan africa

• mostly in asia and latin america

malaria transmission process

1) Transmission to humans (injects sporozoites via bite)

2) sporozoites enter the liver to infect hepatocytes—> mitotic replication

3) liver cells rupture and merozoites released

4) intraerythrocytuc cycle (asexual/symptomatic cycle)

• ring—→ trophozoite——> schizont—→ rupture

5) sexual cycle (merozaites produce gametocytes instead)

6) transmission to mosquito (ingests gametocytes via bite)

7) gametocytes mate, undergo metosis

8) migrates through midgut walls from oocyst

9) soporozoites develop

uncomplicated malaria

symptomatic infection with the malaria parasite, manifesting as fever, body aches, headache, diarrea

severe malaria

symptomatic malaria infection that is complicated by coma or recurrent seizures, severe anemia, respiratory distress, kidney or liver failure, systemic acidosis, and other life threatening ——> immune system can target important organs

testing for current infection

• smear microscopic examination of glemsa-stained, capillary blood

• parasitic nucleic acid detection/polymerase chain reaction

  • limitation-slow test result

  • benefits- can confirm species of parasite

• antigen detection/ rapid diagnostic test

past exposure testing

• serology-detect antibodies against malaria

  • detects past exposure, not current infection

PH interventions for malaria

1) treating people infected w malaria

2) vector control

3) malaria prevention

1) treating people infected with malaria

• if a full- course of correct treatment is provided before severe disease develops, full recovery and cure is possible

• with sever disease, treatment is possible, up to 40% will still die

2) vector control

• emergence of mosquito resistance to insecticide

• rotate use of dif insecticides

3) malaria prevention

• preventing human- mosquito contact

• preventive pharmacologic treatment in uninfected individual

• vaccines

what treatment could we use for malaria

• artemisinin-based combination therapies

• quinine

• supportive care

artemisinin-based combination therapies

• gold standard

• rapidly clear infection

• slow development of drug resistance

• can be given IV

quinine

• used for over 100 years

• toxic

supportive care

hydration, blood, transfusions, monitoring, of glucose and electrolytes

indoor residual spray

• most effective when at least 80% of house is sprayed

• lasts for 1-3 months

• threatened by hesitance to insecticide among mosquitos

larviciding

• application of biological/ chemical insecticides to water

• recommended but low certainty of evidence

insecticide-treated be nets

• most wide- spread preventitive measure

• utilization increasing

• can reduce childhood mortality by 20%

• especially effective outside africa

pharmacologic preventitive treatment

• intermittent preventitive treatment- single dose of SP

• some evidence of parsitic resistance

pre-ervythorocytic vaccines

• target plasmodium during sporozoite and liver stages

• prevent progression of blood-stage disease

blood-stage vaccine

• target blood-stage asexual parasitemia and transmission

• allow for exposure to parasite for naturally-aquired

transmission blocking vaccines

• target sexual stage of parasite development in mosquito

mosquirix vaccine

• first approved malaria vaccine

  • indevelopment since 1980s

  • initial trial result published 2015, pilots ongoing

• first approved vaccine for any parasitic disease

• works vs. plamodium falicparum

R21/matrix-m vaccine

• approved by WHO in 2023

both R21 and mosquirix vaccines

• recommended for children

  • 3 doses between 5-17 months, 4th dose 18 month later

• efficacy-50% against severe malaria in 1st year

  • partial protection; efficacy approx 0 by 4th year

• estimates: could prevent 5.4 million cases, 23,000 deaths

PH barriers to take

• scarcity of labs

• private treatment questionable

• get ACTs to those who need

• drug resistance

• barriers to spray, treatment, tents

• scaling up existing tools