Plasmodium

 Plasmodium

 

Phylum         -     Protozoa

Class             -     Sporozoa 

Order           -     Haemosporidia

 

Members of the genus Plasmodium are collectively known as ma-larial parasites. They cause a febrile disease called malaria. Malaria as a chill and fever disease is known to mankind for a long time. Eradication of malaria is an important problem in public health. For a long time it was believed that malaria was caused by harmful vapours produced in marshy land (Gr. Malo-bad+air). Charles Laveran, a french military surgeon, for the first time, noticed Plasmodium in the blood of a malarial patient, in 1880. Its connection with the intermediate host and the modes of transmission were experimentally worked out in Calcutta by Sir Ronald Ross in 1889. For this discovery he was awarded the nobel prize for medicine in 1902. Grassi (1890) provided absolute scientific proof for the specific relationship between Anopheles mosquito and the human malarial parasite.

 

Plasmodium : The plasmodium is an intracellular sporozoan blood parasite. For the completion of life cycle it requires two hosts, a vertebrate and a blood sucking invertebrate. Transference of the parasite is effected by the inverte-brate host. In man, the infection takes place by the inoculation of the slender, sickle shaped nucleated sporozoite in the blood by the bite of an infected female mosquito belonging to the genus Anopheles. At least four species of Plasmodium, P. vivax, P. falciparum, P. malariae and P. ovale, are known to attack man causing different kinds of malaria.

 

The life cycle of the malarial parasite involves two hosts, the man and the mosquito. The modes of development in these two hosts are different. In man the mode of reproduction is asexual and in mosquito it is sexual. Man is the intermediate host and the mosquito is the definitive host.

Comments

Post a Comment

Popular posts from this blog

Plasma Membrane

  Plasma Membrane   It is the outer limiting membrane of both prokaryotic and eukaryotic cells. It is an ultra thin, elastic, living membrane. Plasma membrane is a dy-namic and selective transport barrier.   Since the plasma membrane is ultra thin, it could be observed only under electron microscope. Structure of the membrane is studied by isolating the same from the cell and conducting biochemical investigations.   In 1895  Overton  suggested that the membrane is made of fatty sub-stances. Other workers later concluded that two layers of lipid were present in the cell membrane. According to a model proposed by  Danielli  and  Davson  in 1935, the  lipid bilayer  of the membrane was coated on either side with protein.   In 1960,  Robertson  using electronmicrographs proposed a  unit   membrane hypothesis . According to this hypothesis the two outer layers of  protein are about 2 nm thick and appear densely granular. They enclose a   clear central area of about 3.5 nm wide consisting of
Read more

THEORIES OF EVOLUTION : Neo-lamarckism

  THEORIES OF EVOLUTION   Neo-lamarckism   Lamarck's 'theory of inhertitance' was further studied by a group of scientists. Their ideas supporting Lamarck's opinion collectively constitute neo-Lamarckism.   The neo-Lamarckians were of the opinion that 'adaptions' are universal in nature. An adaptation happens through causal relationship of structure, function and environment. Due to changes in the environment, habits and life style of organism gets altered. Thus gradually the organism acquires new structures. The newly obtained character gradually becomes an inheritable trait. This opinion and argument is a modified form of Lamarckism. These ideas stressed direct action of environment on organisms.   Support to neo-Lamarckian concept - Experiments   1. McDougall (1938) tried to prove that learning is an acquired character that can be inherited. He did his experiments on rats.   He deviced a 'T' shaped tank. The tank had two exits. One exit was well light
Read more

History of Human anatomy

  History of Human anatomy   The term 'anatomy' is Greek in origin. It takes its root from 'ana' and 'tome' (ana-up ; tome-cutting). Thus anatomy is the science of physical structure of an animal or plant studied by dissection. The Human Anatomy provided the necessary knowledge for surgery and medicine.   The study of human anatomy dates back to 2500 BC, when the Egyptians prepared mummies. They removed internal organs of cadavers be-ing mummified. They also did surgery for wounds and broken bones. In India during 500 - 491 BC Susruta performed cataract operation. In 1 st  century AD, Celsus, a Roman physician wrote about surgical procedures.   The year 1543 AD was significant due to publication of an accurate book on Anatomy by Andreas Vesalius. In 1628 William Harvey described the functioning of heart and the movement of blood in animals. These earlier works were followed by the discovery and accurate account of each and every or-gan system and organs in human
Read more