Haemosporida

Haemosporida is an order of parasitic protozoa within the class Aconoidasida, phylum Apicomplexa. These organisms are known for their complex life cycles, which typically involve both vertebrate and invertebrate hosts. The most well-known members of this order are the Plasmodium species, which are responsible for malaria in humans and other animals.

Life Cycle

Haemosporida have a complex life cycle that involves both sexual and asexual reproduction. The life cycle typically includes the following stages:

1. Sporozoite Stage: The infective stage for the vertebrate host, sporozoites are transmitted through the bite of an infected insect vector, such as a mosquito.
2. Liver Stage (Exoerythrocytic Cycle): Once inside the vertebrate host, sporozoites travel to the liver, where they invade liver cells and undergo asexual reproduction to form merozoites.
3. Blood Stage (Erythrocytic Cycle): Merozoites are released into the bloodstream, where they invade red blood cells and continue to multiply. This stage is responsible for the clinical symptoms of diseases like malaria.
4. Gametocyte Stage: Some merozoites develop into gametocytes, which are the sexual forms of the parasite. These are taken up by the insect vector during a blood meal.
5. Sporogonic Cycle: Inside the insect vector, gametocytes develop into gametes, which fuse to form a zygote. The zygote develops into an ookinete, which penetrates the gut wall and forms an oocyst. The oocyst produces sporozoites, which migrate to the salivary glands of the insect, ready to infect a new vertebrate host.

Pathogenicity

The most significant haemosporidian parasites in terms of human health are the species of the genus Plasmodium, which cause malaria. Malaria is a major public health problem, particularly in tropical and subtropical regions. The disease is characterized by fever, chills, and anemia, and can be fatal if not treated.

Other genera, such as Haemoproteus and Leucocytozoon, primarily infect birds and are of veterinary importance.

Diagnosis and Treatment

Diagnosis of haemosporidian infections typically involves microscopic examination of blood smears, where the parasites can be visualized within red blood cells. Molecular techniques, such as PCR, are also used for more accurate diagnosis.

Treatment of malaria involves the use of antimalarial drugs, such as chloroquine, artemisinin, and their derivatives. Drug resistance is a significant issue in the treatment of malaria, necessitating ongoing research and development of new therapies.

Also see

• Malaria
• Plasmodium
• Apicomplexa
• Vector (epidemiology)
• Protozoa

Apicomplexa Overview
Kingdom	Protista
Phylum	Apicomplexa
Characteristics	Obligate intracellular parasites, complex life cycles, apical complex structure
Notable Genera	Plasmodium, Toxoplasma, Cryptosporidium, Eimeria
Diseases Caused	Malaria, Toxoplasmosis, Cryptosporidiosis, Coccidiosis
Reproduction	Sexual and asexual phases, often involving multiple hosts
Research Importance	Study of parasitic diseases, vaccine development, drug resistance
Related Articles	Protozoa, Parasitology, Infectious disease