Editing Malaria (section)

==Diagnosis==
{{Main|Diagnosis of malaria}}
[[File:5901 lores.jpg|thumb|The blood film is the [[gold standard (test)|gold standard]] for malaria diagnosis.]]
[[File:Plasmodium.jpg|thumb|Ring-forms and [[gametocyte]]s of ''Plasmodium falciparum'' in human blood]]

Due to the non-specific nature of malaria symptoms, diagnosis is typically suspected based on symptoms and travel history, then confirmed with a laboratory test to detect the presence of the parasite in the blood (parasitological test). In areas where malaria is common, the [[World Health Organization]] (WHO) recommends clinicians suspect malaria in any person who reports having fevers, or who has a current temperature above 37.5&nbsp;°C without any other obvious cause.<ref name="WHO-2021a">{{cite book |title=WHO Guidelines for Malaria |date=13 July 2021 |publisher=World Health Organization |chapter=5.1 Diagnosing Malaria (2015) |url=https://www.who.int/publications/i/item/guidelines-for-malaria |access-date=28 November 2021 |archive-date=18 March 2023 |archive-url=https://web.archive.org/web/20230318051541/https://www.who.int/publications/i/item/guidelines-for-malaria |url-status=live }}</ref> Malaria should be suspected in children with signs of [[anemia]]: [[Palmar pallor|pale palms]] or a laboratory test showing [[hemoglobin]] levels below 8 [[gram]]s per [[deciliter]] of blood.<ref name="WHO-2021a"/> In areas of the world with little to no malaria, the WHO recommends only testing people with possible exposure to malaria (typically travel to a malaria-endemic area) and unexplained fever.<ref name="WHO-2021a"/>

In sub-Saharan Africa, testing is low, with only about one in four (28%) of children with a fever receiving medical advice or a rapid diagnostic test in 2021. There was a 10-percentage point gap in testing between the richest and the poorest children (33% vs 23%). Additionally, a greater proportion of children in Eastern and Southern Africa (36%) were tested than in West and Central Africa (21%).<ref name="UNICEF DATA-2" /> According to UNICEF, 61% of children with a fever were taken for advice or treatment from a health facility or provider in 2021. Disparities are also observed by wealth, with an 18 percentage point difference in care-seeking behaviour between children in the richest (71%) and the poorest (53%) households.<ref name="UNICEF DATA-2" />

Malaria is usually confirmed by the microscopic examination of [[blood film]]s or by [[antigen]]-based [[Malaria antigen detection tests|rapid diagnostic tests]] (RDT). Microscopy—i.e. examining [[Giemsa]]-stained blood with a [[light microscope]]—is the [[Gold standard (test)|gold standard]] for malaria diagnosis.<ref name="Ashley-2018"/> Microscopists typically examine both a "thick film" of blood, allowing them to scan many blood cells in a short time, and a "thin film" of blood, allowing them to clearly see individual parasites and identify the infecting ''Plasmodium'' species.<ref name="Ashley-2018"/> Under typical field laboratory conditions, a microscopist can detect parasites when there are at least 100 parasites per [[microliter]] of blood, which is around the lower range of symptomatic infection.<ref name="WHO-2021a"/> Microscopic diagnosis is relatively resource intensive, requiring trained personnel, specific equipment and a consistent supply of [[Microscope slide|microscopy slides]] and stains.<ref name="WHO-2021a"/>

In places where microscopy is unavailable, malaria is diagnosed with RDTs, [[rapid antigen test]]s that detect parasite proteins in a [[fingerstick]] blood sample.<ref name="WHO-2021a"/> A variety of RDTs are commercially available, targeting the parasite proteins histidine rich protein 2 (HRP2, detects ''P. falciparum'' only), [[lactate dehydrogenase]], or [[aldolase]].<ref name="WHO-2021a"/> The HRP2 test is widely used in Africa, where ''P. falciparum'' predominates.<ref name="Ashley-2018"/> However, since HRP2 persists in the blood for up to five weeks after an infection is treated, an HRP2 test sometimes cannot distinguish whether someone currently has malaria or previously had it.<ref name="WHO-2021a"/> Additionally, some ''P. falciparum'' parasites in the Amazon region lack the ''HRP2'' gene, complicating detection.<ref name="WHO-2021a"/> RDTs are fast and easily deployed to places without full diagnostic laboratories.<ref name="WHO-2021a"/> However they give considerably less information than microscopy, and sometimes vary in quality from producer to producer and lot to lot.<ref name="WHO-2021a"/>

[[Serological test]]s to detect antibodies against ''Plasmodium'' from the blood have been developed, but are not used for malaria diagnosis due to their relatively poor sensitivity and specificity. Highly sensitive [[nucleic acid amplification test]]s have been developed, but are not used clinically due to their relatively high cost, and poor specificity for active infections.<ref name="WHO-2021a"/>

===Classification===
Malaria is classified into either "severe" or "uncomplicated" by the [[World Health Organization]] (WHO).<ref name="Nadjm-2012" /> It is deemed severe when ''any'' of the following criteria are present, otherwise it is considered uncomplicated.{{sfn|WHO|2015|p=73}}
* Decreased consciousness
* Significant weakness such that the person is unable to walk
* Inability to feed
* Two or more [[convulsions]]
* [[Low blood pressure]] (less than 70&nbsp;[[mmHg]] in adults and 50&nbsp;mmHg in children)
* [[respiratory distress|Breathing problems]]
* [[Circulatory shock]]
* [[Kidney failure]] or [[haemoglobin|hemoglobin]] in the urine
* Bleeding problems, or hemoglobin less than 50&nbsp;g/L (5&nbsp;g/dL)
* [[Pulmonary oedema]]
* [[Blood glucose]] less than 2.2&nbsp;mmol/L (40&nbsp;mg/dL)
* [[Acidosis]] or [[lactic acid|lactate]] levels of greater than 5&nbsp;mmol/L
* A parasite level in the blood of greater than 100,000 per [[microlitre]] (μL) in low-intensity transmission areas, or 250,000 per μL in high-intensity transmission areas

Cerebral malaria is defined as a severe ''P.&nbsp;falciparum''-malaria presenting with neurological symptoms, including coma (with a [[Glasgow coma scale]] less than 11, or a [[Blantyre coma scale]] less than 3), or with a coma that lasts longer than 30 minutes after a seizure.{{sfn|WHO|2015|p=3}}