Malaria Overview and History

Study Notes

Malaria is one of the oldest known diseases.
King Tutankhamun may have died from malaria.
References to malaria have been recorded for nearly 6,000 years, with the earliest records coming from China.
The first advances in malaria research were made in 1880 by French army doctor Charles Laveran.
Charles Laveran observed parasites inside red blood cells of malaria patients and proposed that a protozoan caused the disease.
Ronald Ross discovered that mosquitoes transmitted malaria in 1898.
The first effective malaria medicine was discovered by Pierre Pelletier and Joseph Caventou and is called quinine. Quinine comes from the bark of cinchona trees in Peru.

Malaria is the world’s most deadly vector-borne human disease.
40% of the world’s population lives in malaria endemic areas.
There are 300-500 million clinical cases of malaria each year.
1.5-2.7 million deaths from malaria occur each year, with 90% of these deaths occurring in Africa.
Malaria is a re-emerging disease with an increasing problem due to a resurgence in some areas and drug resistance leading to increased mortality.
Both men and women are affected equally.
Young children aged 6 months to 3 years who live in endemic areas are at an increased risk of death from malaria.

There are five Plasmodium species known to cause malaria in humans:
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
P. vivax is the most widespread malaria infection in the world.
P. falciparum and P. knowlesi cause the most severe malaria disease and are responsible for the most deaths and morbidity.
Malaria is transmitted by Anopheles mosquitoes.

Species	Periodicity	Parasites/Ml	RBC Age	Hypnozoite	Duration (yrs.)
P. falciparum	48	50-2000	Any	N	1-2
P. malariae	72	6-20	Old	N	3->50
P. ovale	50	9-30	Young	Y	1.5-5
P. vivax	48	20-50	Young	Y	1.5-5

Malarial parasite trophozoites are generally ring-shaped and 1-2 microns in size but can also exist in other forms like ameboid and band forms.
The sexual forms of the parasite (gametocytes) are much larger (7-14 microns in size).
P. falciparum is the largest of the species and banana-shaped. Other species are smaller and round.

The incubation period for malaria varies from 7 to 30 days.
Shorter periods are seen most frequently with P. falciparum and longer ones with P. malariae.
Fever in the first week of travel in a malaria-risk area is unlikely to be malaria.
Anyone who develops fever or flu-like illness while traveling in a malaria-risk area or up to one year after returning home should seek immediate medical care.

Asymptomatic malaria – Infections are still poorly understood and remains a challenge for malaria control programs as it significantly influences transmission dynamics.
Mild and uncomplicated malaria – Symptomatic infection with evidence of malaria parasites but no signs of severity or vital organ involvement.
Severe and complicated malaria – Vital organ dysfunction, including cerebral malaria, severe anemia, respiratory distress, and acute renal failure.
Chronic malaria – Longterm complications due to persistent parasitic infection.