Introduction to Plasmodium

It is an intracellular protozoan parasite. It is also a digenetic parasite i.e. it needs two hosts for completion of lifecycle one is human and the other is female anopheles mosquito. Female anopheles mosquito also acts as a vector ( an insect which transmits causative agent from one person to another). Only 4 species of Plasmodium are infective to man which causes malaria.

P.vivax → BenginTertian Malaria

P. falciparum → Malignant Tertian Malaria

P. malaria → Quartan Malaria

P. ovale → Mild Tertian Malaria

Plasmodium falciparum is the most dangerous species. It cause cerebral malaria and black water fever.

Plasmodium vivax

Classification:

kingdom: Protista

Phylum : Protozoa

Class : Sporozoa

Genus : Plasmodium

Species : Vivax

Common name : Malarial parasite

Habit, Habitat, and Distribution

• It is an intracellular protozoan parasite.
• It lives inside RBC and liver cell of the human host, stomach and salivary gland of mosquito host.
• It is worldwide in distribution.
• It is the most common species mainly found in hot tropical and temperate region of the world.

In Nepal, it is common in terai region. 10 districts of the hilly region are reported as malaria free district.

Structure of Plasmodium:

It mostly occurs in two different morphological stages:

• Trophozoite
• Sporozoite

Incubation period:

It is the period between initial infection of sporozoites and appearance of the first symtom. It is of 14 days in P.vivax.

Paroxysm:

The rise of malarial fever at the interval of every 48 hours is called paroxysm. Such fever is also called intermittent or relapsing fever.

Relapse:

It is the reoccurrence of malarial symptoms after the certain time period of treatment. It is caused by crypto merozoites of the previous infection as they are unaffected by anti-malarial drugs.