Geographic Distribution

Where malaria is found depends mainly on climatic factors such as temperature, humidity, and rainfall.
Malaria generally occurs in areas where environmental conditions allow parasite multiplication in the vector.
Temperature is particularly critical. Thus, at temperatures below 20°C (68°F), ), Plasmodium falciparum (which causes severe malaria) cannot complete its growth cycle in the Anopheles mosquito, and thus cannot be transmitted.
In tropical and subtropical areas, where Anopheles mosquitoes can survive and multiply, the Malaria parasites can complete their growth cycle in the mosquitoes.

Parasite	Host	Geographical distribution
P. vivax	Human	Africa, Asia, South/Central America
P. malariae	Human	Africa, Asia, South/Central America
P. ovale	Human	Africa
P. falciparum	Human	Africa, Asia, South/Central America
P. knowlesi	Human/monkeys	Asia

Trends in the Burden of Malaria

Malaria cases:
- Globally, there were an estimated 229 million malaria cases in 2019 in 87 malaria endemic countries, declining from 238 million in 2000.
At the Global technical strategy for malaria 2016–2030 (GTS) baseline of 2015, there were 218 million estimated malaria cases.
- Twenty-nine countries accounted for 95% of malaria cases globally. Nigeria (27%), the Democratic Republic of the Congo (12%), Uganda (5%), Mozambique (4%) and Niger (3%) accounted for about 51% of all cases globally.
- The World Health Organization (WHO) African Region, with an estimated 215 million cases in 2019, accounted for about 94% of cases.

Malaria deaths:
- Globally, malaria deaths have reduced steadily over the period 2000–2019, from 736000 in 2000 to 409000 in 2019.
The percentage of total malaria deaths among children aged under 5 years was 84% in 2000 and 67% in 2019.
The global estimate of deaths in 2015, the GTS baseline, was about 453000.
- About 95% of malaria deaths globally were in 31 countries.
Nigeria (23%), the Democratic Republic of the Congo (11%), the United Republic of Tanzania (5%), Mozambique (4%), Niger (4%) and Burkina Faso (4%) accounted for about 51% of all malaria deaths globally in 2019.

Malaria cases and deaths averted:
- Most of the cases (82%) and deaths (94%) averted were in the WHO African Region, followed by the WHO South-East Asia Region (cases 10% and deaths 3%).

Content sources:
1.Global Health, Division of Parasitic Diseases and Malaria
URL: https://www.cdc.gov/malaria/malaria_worldwide/impact.html
2.World malaria report 2020: 20 years of global progress and challenges, World Health Organization 2020
URL: https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2020

Mosquito Life cycle

The mosquito has four distinct stages in its life cycle: egg, larva, pupa, and adult.
The adult is an active flying insect, while the larvae and pupae are aquatic and occur only in water.
Depending on the species, eggs are laid either on the surface of water or are deposited on moist soil or other objects that will often be flooded.

Scientific classification

Mosquitoes are members of a group of about 3,500 species of small flies within the family Culicidae (from the Latin culex meaning "gnat").
The word "mosquito" (formed by mosca and diminutive -ito) is Spanish for "little fly".
Mosquitoes have a slender segmented body, one pair of wings, one pair of halteres, three pairs of long hair-like legs, and elongated mouthparts.

Kingdom	Animalia
Phylum	Arthropoda
Class	Insecta
Order	Diptera
Superfamily	Culicoidea
Family	Culicidae
Subfamilies	- Anophelinae - Culicinae

Vectors of disease

Anopheles albimanus mosquito feeding on a human arm – this mosquito is a vector of malaria, and mosquito control is a very effective way of reducing the incidence of malaria.
Mosquitoes can act as vectors for many disease-causing viruses and parasites. Infected mosquitoes carry these organisms from person to person without exhibiting symptoms themselves.
The parasitic diseases collectively called malaria, caused by various species of Plasmodium, carried by female mosquitoes of the genus Anopheles.

Content sources:
1. Mosquito, Wikipedia
URL: https://en.wikipedia.org/wiki/Mosquito

Microbiology

A Plasmodium is an ameboid, multinucleate mass or sheet of cytoplasm characteristic of some stages of organisms, as of myxomycetes or slime molds.
A multinucleate mass of cytoplasm formed by the aggregation of a number of amoeboid cells, as that characteristic of the vegetative phase of the slime molds.
A genus of protozoans that are parasites of the red blood cells of vertebrates and include the causative agents of malaria.

Classification

super kingdom	Eukaryotic
reign	Chromalveolata
Superphylum	Alveolata
Phylum	Apicomplexa
Class	Aconoidasida
Subclass	Hematozoa
Order	Haemosporida
Suborder	Haemosporidiidea
Family	Plasmodiidae
Genus	Plasmodia
Subgenus	Plasmodium Laverania
Species	- P. Falciparum - P. Vivax - P. Oval - P. Malariae - P. Knowlesi

Content sources:
1. Plasmodium, Dictionary.com
URL: https://www.dictionary.com/browse/plasmodium 2. Plasmodium, Wikipedia
URL: https://en.wikipedia.org/wiki/Plasmodium
Malaria, Global Health, Division of Parasitic Diseases and Malaria
URL: https://www.cdc.gov/dpdx/malaria/index.html

Species and Causal Agent

Blood parasites of the genus Plasmodium. There are approximately 156 named species of Plasmodium which infect various species of vertebrates.
Four species are considered true parasites of humans, as they utilize humans almost exclusively as a natural intermediate host: P. falciparum, P. vivax, P. ovale and P. malariae.
However, there are periodic reports of simian malaria parasites being found in humans, most reports implicating P. knowlesi.
At the time of this writing, it has not been determined if P. knowlesi is being naturally transmitted from human to human via the mosquito, without the natural intermediate host (macaque monkeys, genus Macaca).
Therefore, P. knowlesi is still considered a zoonotic malaria.

Plasmodium Life Cycle

1.- The malaria parasite life cycle involves 2 hosts. During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoites into the human host.
2.- Sporozoites infect liver cells.
3.- There, the sporozoites mature into schizonts.
4.- The schizonts rupture and release merozoites. This initial replication in the liver is called the exoerythrocytic cycle.
5.- Merozoites infect RBCs. There, the parasite multiplies asexually (called the erythrocytic cycle). The merozoites develop into ring-stage trophozoites. Some then mature into schizonts.
6.- The schizonts rupture, releasing merozoites.
7.- Some trophozoites differentiate into gametocytes.
8.- During a blood meal, an Anopheles mosquito ingests the male (microgametocytes) and female (macrogametocytes) gametocytes, beginning the sporogonic cycle.
9.- In the mosquito’s stomach, the microgametes penetrate the macrogametes, producing zygotes.
10.- The zygotes become motile and elongated, developing into ookinetes.
11.- The ookinetes invade the midgut wall of the mosquito where they develop into oocysts.
12.- The oocysts grow, rupture, and release sporozoites, which travel to the mosquito’s salivary glands. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle.

Content sources:
URL: https://www.msdmanuals.com/professional/multimedia/figure/inf_plasmodium_life_cycle