Chapter 43, Problem 1O

Summary Introduction

To discuss:

The infectious process associated with helminthic infections, protozoal infections, and malarial infections.

Concept introduction:

Malaria is the most important protozoal disease (in terms of mortality and morbidity). Malaria is a deadly disease that is caused by Plasmodium (protozoan parasite).  Plasmodium is a unicellular eukaryotic organism. It is a parasite (obligate) of insects and vertebrates. There are four types of Plasmodium species such as P. falciparum, P. vivax, P. malariae, and P. ovale. About 350 million-500 million people (worldwide) are infected by malaria and the death rate is about one million – two million people. Around one million infant death (malaria) is recorded only in Africa. Sub-Saharan Africa, Latin America, and Southeast Asia are the geographical areas, where malaria is highly prevalent.

Helminthic infections are caused by parasitic worms like ascardia, liver fluke, and tapeworm.

Explanation of Solution

The infectious process associated with helminthic infections, protozoal infections, and malarial infections are as follows:

Malarial infections:

Malarial transmission occurs by the bite of an infested mosquito (female anopheline). It is also caused congenitally (mother to fetus) and by blood transfusions.

The life cycle of Plasmodium species involves two stages. They are sexual cycle (inside the mosquito) and asexual cycle (occurs in the human being). The asexual cycle consists of two phases, which includes the exoerythrocytic phase (other than erythrocytes) and erythrocytic phase (occurs inside the erythrocyte) or blood phase.

An anopheles (infected) mosquito acts as a carrier to transport the parasite into the human. The liver is the place where the parasite gets matured and enters into the blood and starts breaking the red blood cells.

Helminthic infections:

Helminthic infections are considered as a worldwide problem. It is also called as worm infections. Cestodes (tapeworm), Nematodes (roundworms), Platyhelminthes (flatworms), and Trematodes (flukes) are helminths that act as parasites in human beings. There are three stages of helminth life cycle: egg, larvae, and adult. A host (definitive) is infected by an adult worm. These parasites initially infect and reside in the intestine of the host. The other larval stages may be parasitized vectors of invertebrates or free-living.

Other protozoal infections:

Protozoal infections include Giardiasis (causative agent is Giardia lamblia), Toxoplasmosis (causative agent is Toxoplasma gondii), Amebiasis (causative agent is Entamoebahistolytica), and Trichomoniasis (causative agent is Trichomonas vaginalis). They are transmitted by sexual contact (person to person), contaminated food or water ingestion, bite of an insect (direct handling of the parasite). They initially infect residues in the human liver and slowly travel to various parts of the body like the liver.

Conclusion

The infectious process associated with helminthic infections, protozoal infections, and malarial infections are discussed.