Life cycle of Malaria Parasite

The malaria parasite life cycle involves two hosts. During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoites into the human host . Sporozoites infect liver cells and mature into schizonts , which rupture and release merozoites . (Of note, in P. vivax and P. ovale a dormant stage [hypnozoites] can persist in the liver and cause relapses by invading the bloodstream weeks, or even years later.) After this initial replication in the liver (exo-erythrocytic schizogony ), the parasites undergo asexual multiplication in the erythrocytes (erythrocytic schizogony ). Merozoites infect red blood cells . The ring stage trophozoites mature into schizonts, which rupture releasing merozoites . Some parasites differentiate into sexual erythrocytic stages (gametocytes) . Blood stage parasites are responsible for the clinical manifestations of the disease.

The gametocytes, male (microgametocytes) and female (macrogametocytes), are ingested by an Anopheles mosquito during a blood meal . The parasites’ multiplication in the mosquito is known as the sporogonic cycle . While in the mosquito's stomach, the microgametes penetrate the macrogametes generating zygotes . The zygotes in turn become motile and elongated (ookinetes) which invade the midgut wall of the mosquito where they develop into oocysts . The oocysts grow, rupture, and release sporozoites , which make their way to the mosquito's salivary glands. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle.

Lymphatic Filariasis

Mansonia uniformis - vector of Brugia malayi & B. timori

Lymphatic filariasis is infection with the filarial worms, Wuchereria bancrofti, Brugia malayi or B. timori. These parasites are transmitted to humans through the bite of an infected mosquito and develop into adult worms in the lymphatic vessels, causing severe damage and swelling (lymphoedema). Elephantiasis – painful, disfiguring swelling of the legs and genital organs – is a classic sign of late-stage disease.

Water Hyacinth - breeding site of Mansonia species

 The infection can be treated with drugs. However, chronic conditions may not be curable by anti-filarial drugs and require other measures, eg. surgery for hydrocele, care of the skin and exercise to increase lymphatic drainage in lymphoedema.

Egg of Mansonia

Larva of Mansonia

Pupa of Mansonia

 Annual treatment of all individuals at risk (individuals living in endemic areas) with recommended anti-filarial drugs combination of either diethyl-carbamazine citrate (DEC) and albendazole, or ivermectin and albendazole; or the regular use of DEC fortified salt can prevent occurrence of new infection and disease.

Broncraftian microfilaria