Plasmodium falciparum
Plasmodium falciparum is a unicellular protozoan parasite of humans, and the deadliest species of "Plasmodium" that cause malaria in humans. It is transmitted through the bite of a female "Anopheles" mosquito. It is responsible for roughly 50% of all malaria cases. It causes the disease's most dangerous form called falciparum malaria. It is therefore regarded as the deadliest parasite in humans, causing 435,000 deaths in 2017. It is also associated with the development of blood cancer (Burkitt's lymphoma) and is classified as Group 2A carcinogen.
Dengue virus
Common names for dengue fever include breakbone fever and dandy fever; dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) are the severe forms. Dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas. People of all ages who are exposed to infected mosquitoes are possible victims to dengue fever. The disease occurs most often during the rainy season in tropical countries in Asia and South America with high numbers of infected mosquitoes. The virus is transmitted to humans through the bites of infected female mosquitoes, though humans are not capable of transmitting the disease and are not contagious. The incubation period is 3 to 14 days, while the period of the illness is 3–7 days. Signs and symptoms may include severe headache; retroorbital pain; muscle, joint, and bone pain; macular or maculopapular rash; and minor hemorrhagic manifestations, including petechiae, ecchymosis, purpura, epistaxis, bleeding gums, hematuria, or a positive tourniquet test result.There are multiple reasons why some people suffer from more severe forms of dengue, such as dengue hemorrhagic fever. Different strains of viruses interacting with people with different immune backgrounds lead to a complex interaction. Among the possible causes are cross-serotypic immune response, through a mechanism known as antibody-dependent enhancement, which happens when a person who has been previously infected with dengue gets infected for the second, third or fourth time. The previous antibodies to the old strain of dengue virus now interfere with the immune response to the current strain, leading paradoxically to more virus entry and uptake.