Malaria E-book Flashcards
Malaria occurs through
the transmission of plasmodium parasite, through the bite of a female Anopheles mosquito.
Types of malaria
Plasmodium falciparum is the most common type of malaria parasite, prominently in Africa, and is the main reason for malaria deaths worldwide. Plasmodium vivax mainly found in America and Asia. The P. vivax parasite has milder symptoms than P. falciparum, but may cause relapses as it can stay in the liver for up to 3 years. Plasmodium ovale is found in western Africa and is
very uncommon. Plasmodium malariae and Plasmodium knowlesi are very rare However, P. knowlesi may be transmitted to humans from monkeys through bites from mosquitoes known as Anopheles balabacensis.
After an individual has been bitten, the infection develops in the liver and then travels into the bloodstream where the red blood cells become infected. This leads to the parasite to grow and multiply in the red blood cells, causing red blood cells to burst at regular intervals (infected blood cells burst every 48-72 hours), releasing more parasites in the blood. Every time the blood cells burst the symptoms of fever, chills and sweats are amplified
There are 5 species of plasmodium can infect humans and cause illness:
● Plasmodium falciparum ( P. falciparum) ● Plasmodium malariae (P. malariae) ● Plasmodium vivax (P. vivax) ● Plasmodium ovale (P. ovale) ● Plasmodium knowlesi (P. knowlesi)
The most common form of malaria is caused by
● Plasmodium falciparum ( P. falciparum)
Which infections can cause rapidly progressive severe illness or death
P. falciparum and P. knowlesi
less likely to cause severe manifestations.
P. vivax, P. ovale, or P. malariae
Shorter incubation periods are observed most frequently
with
P. falciparum
Longer incubation periods are observed most frequently
with
P. malariae
General symptoms include
- Fever (often 39oC or higher), sweats and/or chills — (absence of fever should not remove the suspicion of malaria).
- Headache.
- General malaise, lethargy and fatigue
— drowsiness is more common in children than adults. - Anorexia, gastrointestinal disturbance (such as nausea, abdominal pain, vomiting, diarrhoea) and jaundice.
- Poor feeding in children.
- Myalgia and arthralgia.
- Sore throat, cough, lower respiratory tract symptoms and respiratory distress.
- Confusion
Plasmodium vivax and Plasmodium ovale
In P. vivax and P. ovale infections they are rarely complicated, however there is evidence on the risk of serious and fatal complications due to P. vivax infections. Both P. vivax and P. ovale infection produce hypnotize forms that are dormant in the liver
The classical malaria paroxysm presents in three stages;
a cold stage, followed by a hot stage, with a terminal sweating stage.
- Individuals may shiver and their teeth may chatter, in cases of intense peripheral vasoconstriction – their skin may be cold, cyanosed and goose-pimpled. This initial
stage can usually last 10-30 minutes, occasionally up to 90 minutes. - Once the hot stage starts, shivering will cease and the skin will then become hot and dry with symptoms of face flushing. Vomiting is also common in this phase and
sometimes diarrhoea, severe retro-orbital headache, extreme thirst and altered consciousness may occur – convulsions may occur in young children. - Within 2-6 hours, an individual will enter third stage, which is known as the sweating stage; this entails sudden profuse sweating, starting at the temples and then becoming generalised. Temperature will then fall rapidly and the individual will start to feel ‘well’, however they will also experience extreme tiredness and may fall asleep. The sweating stage can last 2-3 hours, with the entire process lasting around 6-10 hours.
Plasmodium falciparum
In P. falciparum malaria, an onset of fever occurs after a few days of prodromal symptoms started during the last days of the incubation period (usually 9-14 days). Initially, the fever is irregular but usually occurs daily.
This fever may intermittent or continuous and will show no signs of periodicity until the illness has continued for a week or more. Anorexia, dyspepsia, epigastric discomfort, nausea and vomiting and watery diarrhoea are also frequent and may be misdiagnosed as a GI infection.
Herpes labialis, a dry cough and an increase in respiratory rate may also be observed.
On non-specific physical examination, a tender spleen, orthostatic hypotension and jaundice may be observed. Moreover, the pulse may be rapid (100-120 bpm) and blood pressure may be low (90-100 mmHg, systolic).
Plasmodium malariae
P. malaria causes the mildest and most persistent form of malaria infection. After the incubation period, prodromal symptoms which resemble those of vivax malaria can occur after the onset of fever. The onset is usually gradual but are typically separated by intervals of 72h.
Plasmodium knowlesi
P. knowlesi is a species of plasmodium which has been most recently been identified as an agent of human malaria. On the basis of clinical features, it is not possible distinguish knowlesi malaria from vivax or falciparum malaria. However hyperparasitemia and other complications are fairly common
Drugs for chemoprophylaxis of Malaria
Drugs for chemoprophylaxis of Malaria
● Chloroquine
It may lower blood glucose and increase muscle weakness.
Handle with care in elderly and in patients with neurological disorders, avoiding in
epilepsy.
Avoid in severe gastrointestinal disorders, renal impairment and moderate to severe
hepatic impairment.
Side effects at malaria prophylactic doses are usually not serious.
It can be used by pregnant or breastfeeding women since the benefit is higher than the risk.
● Doxycycline
Muscle weakness may be increased.
Use with caution in renal impairment and use with caution or avoid in hepatic impairment.
Avoiding sunlight or if not possible use high protection.
Common side effects include dyspnoea; hypotension; peripheral oedema; tachycardia, angioedema; diarrhoea; headache; hypersensitivity; nausea; pericarditis; photosensitivity reaction; skin reactions; vomiting.
When traveling to malarious areas is unavoidable during pregnancy, doxycycline can be used for malaria prophylaxis if other regimens are unsuitable, and if the entire course of doxycycline can be completed before 15 weeks’ gestation. This is because doxycycline affects skeletal development.
Not for use when breastfeeding.
● Proguanil Hydrochloride
Use with care in renally impaired patients; adjust doses if necessary.
Benefit of prophylaxis outweighs risk in pregnancy, adequate folate supplements should be given to mother.
Not known to be harmful during breastfeeding.
● Mefloquine
Avoid if history of psychiatric disorders or convulsions.
Cautions include cardiac conduction disorders; epilepsy; infants under 3 months (5 kg);
traumatic brain injury, cautioned in renal impairment, avoid in severe hepatic impairment.
Side effects may include anxiety; depression; diarrhoea; dizziness; gastrointestinal discomfort; headache; nausea; skin reactions; sleep disorders; vision disorder and
vomiting.
Manufacturer advises contraception during prophylaxis and for 3 months after stopping.
Avoid in pregnancy (particularly in the first trimester).
Minimal risk in breastfeeding.
● Atovaquone with Proguanil Hydrochloride
Diarrhoea or vomiting reduces the absorption of atovaquone. If occurs, speak to your doctor.
Avoid if eGFR<30.
Side effects include: abdominal pain; appetite decreased; cough; depression; diarrhoea; dizziness; fever; headache; nausea; skin reactions; sleep disorders and vomiting.
Avoid in pregnancy and breastfeeding unless it is essential
