RAS Pre 2021, held on 27 October 2021. Question text as printed in RPSC's booklet; answer as per RPSC's final answer key.

Malignant malaria is caused by -

Q: What is the answer to RAS Pre 2021 Q94?

(4). Correct — option (4), Plasmodium falciparum. NCERT's Class 12 Biology chapter Human Health and Disease names three Plasmodium species, P. vivax, P. malaria (as NCERT spells it) and P. falciparum, and singles one out: "Of these, malignant malaria caused by Plasmodium falciparum is the most serious one and can even be fatal." WHO's malaria fact sheet (dated 1 April 2021) agrees on severity. It calls P. falciparum "the most deadly malaria parasite globally" and warns that, if not treated within 24 hours, P. falciparum malaria can progress to severe illness, often leading to death. So malignant malaria is caused by Plasmodium falciparum. The idea to remember: malignant means the most dangerous form — P. falciparum.

(1)Plasmodium vivax
(2)Plasmodium ovale
(3)Plasmodium malariae
(4)Plasmodium falciparum

Answer

(4)

Why

Correct — option (4), Plasmodium falciparum.

NCERT's Class 12 Biology chapter Human Health and Disease names three Plasmodium species, P. vivax, P. malaria (as NCERT spells it) and P. falciparum, and singles one out: "Of these, malignant malaria caused by Plasmodium falciparum is the most serious one and can even be fatal."

WHO's malaria fact sheet (dated 1 April 2021) agrees on severity. It calls P. falciparum "the most deadly malaria parasite globally" and warns that, if not treated within 24 hours, P. falciparum malaria can progress to severe illness, often leading to death.

So malignant malaria is caused by Plasmodium falciparum.

The idea to remember: malignant means the most dangerous form — P. falciparum.

Why the others are wrong

(1)
Plasmodium vivax — P. vivax causes recurring malaria. Wikipedia's P. vivax article (July 2021 revision) calls it the most frequent and widely distributed cause of recurring malaria, and less virulent than P. falciparum.
It is still serious: WHO names P. falciparum and P. vivax as the two species that pose the greatest threat, and P. vivax is the predominant parasite in the WHO Region of the Americas.
(2)
Plasmodium ovale — P. ovale causes tertian malaria. Wikipedia's article (September 2021 revision) says it is rare compared with P. falciparum and P. vivax and substantially less dangerous than P. falciparum.
Some of its parasites can stay dormant in liver cells as hypnozoites, which is how one infection can relapse; the article says relapse may occur up to 4 years after infection.
(3)
Plasmodium malariae — P. malariae causes quartan malaria, with fevers recurring at about three-day intervals. Wikipedia's article (May 2021 revision) says it causes a so-called "benign malaria", not nearly as dangerous as P. falciparum or P. vivax.
Its developmental cycle in the blood is about 72 hours, against 48 hours for P. vivax and P. falciparum, and its infection can become chronic.

Concept

Malaria is caused by Plasmodium, a protozoan. NCERT describes its life cycle across two hosts, human and mosquito.

An infected female Anopheles mosquito injects sporozoites while biting. The parasites first multiply in liver cells, then attack red blood cells and rupture them. The rupture releases a toxic substance, haemozoin, which NCERT links to the chill and high fever.

A mosquito biting an infected person takes up parasites, which develop into sporozoites stored in its salivary glands.

RPSC's 2021 syllabus lists "Health care; Infectious, Non-Infectious and Zoonotic diseases." under Science & Technology.

WHO's fact sheet (1 April 2021) cites the World malaria report of 30 November 2020: an estimated 229 million malaria cases and 409 000 deaths worldwide in 2019, with children under 5 accounting for 67% of deaths.

The same sheet says P. falciparum accounted for 50% of estimated cases in the WHO South-East Asia Region in 2018, and names artemisinin-based combination therapy as the best available treatment for P. falciparum malaria.

Key facts

NCERT: malignant malaria, caused by Plasmodium falciparum, is the most serious type and can even be fatal.
WHO (1 April 2021): 5 parasite species cause malaria in humans; P. falciparum and P. vivax pose the greatest threat.
WHO: if not treated within 24 hours, P. falciparum malaria can progress to severe illness, often leading to death.
Plasmodium enters humans as sporozoites through the bite of an infected female Anopheles mosquito, multiplies in the liver, then attacks red blood cells.
NCERT: the malarial parasite needs two hosts, human and mosquito, and the female Anopheles mosquito is also its vector.

Human malaria parasites named in the options

Plasmodium falciparum→Malignant malaria; the most serious type (NCERT)

Plasmodium vivax→Recurring malaria; with P. falciparum, the greatest threat (WHO)

Plasmodium ovale→Tertian malaria; rare; dormant liver stage can relapse

Plasmodium malariae→Quartan malaria (fever about every three days); "benign malaria"

From NCERT Class 12 Biology, WHO's malaria fact sheet (1 April 2021) and Wikipedia's species articles (2021 revisions).

Study next

Life cycle of Plasmodium in human and mosquitoVector-borne diseases and their vectorsTertian and quartan fever patternsMalaria vaccine RTS,S/AS01Artemisinin-based combination therapy

Common traps

Most widespread is not most dangerous: P. vivax is the most widely distributed cause of recurring malaria, but P. falciparum causes malignant malaria.
Recurrence is not severity: P. vivax causes recurring malaria and P. ovale infections can relapse, yet neither is the malignant form.
'Benign malaria' belongs to P. malariae, the quartan parasite, the opposite label to malignant.

A question can name a type of malaria and ask which Plasmodium species causes it, or name a species and ask for its fever pattern.

A question can also match diseases with their vectors and pathogens, such as Anopheles, malaria and a protozoan parasite.

Related PYQs

RPSC_2023_PRE_GS_Q702023Open & attempt →

Species of Plasmodium which causes Malignant Malaria :

(1) Vivax
(2) Falciparum
(3) Ovale
(4) Malarial

Answer(2)

Same fact, asked two years later: that question asks for the species of Plasmodium which causes malignant malaria, with options Vivax, Falciparum, Ovale and Malarial (RPSC's key: option (2), Falciparum). Here the options give full binomial names.

RPSC_2024_PRE_GS_Q702024Open & attempt →

Select the incorrect set of “the typical Vector – Disease caused – Type of Pathogen”.

(1) Aedes – Chikungunya – Bacteria
(2) Culex – Lymphatic Filariasis – Parasite
(3) Anopheles – Malaria – Parasite
(4) Aedes – Dengue – Virus

Answer(1)

Same disease from another angle. That question asks for the incorrect set of typical vector, disease caused and type of pathogen, and includes Anopheles – Malaria – Parasite (RPSC's key: option (1), Aedes – Chikungunya – Bacteria); this one asks which Plasmodium species causes malignant malaria.

Practice

practice — not a real PYQ
According to NCERT, the malarial parasite enters the human body in which form?
- (a)Merozoites
- (b)Sporozoites
- (c)Gametocytes
- (d)Haemozoin
Answer(2) — NCERT says Plasmodium enters the human body as sporozoites, the infectious form, through the bite of an infected female Anopheles mosquito. Option (4) is the toxic substance released when red blood cells rupture, and options (1) and (3) are not the form NCERT names for entry.
practice — not a real PYQ
Quartan malaria, with fevers recurring at about three-day intervals, is caused by –
- (a)Plasmodium falciparum
- (b)Plasmodium vivax
- (c)Plasmodium malariae
- (d)Plasmodium ovale
Answer(3) — Wikipedia's P. malariae article describes quartan fevers at about three-day intervals from a 72-hour cycle. Options (1) and (2) have 48-hour cycles, and option (4) causes tertian malaria.