Malaria is a potentially deadly tropical disease characterized by cyclical bouts of fever with muscle stiffness, shaking and sweating. It is caused by a tiny parasite (genus Plasmodium) that is transmitted by the female mosquito (genus Anopheles) when it feeds on blood for its developing eggs. Severe malaria is not readily distinguishable from other severe diseases, such as pneumonia typhoid and meningitis that require very different therapy. Almost all vertebrates, birds, snakes and monkeys, for example, can be infected by Plasmodium (malaria) parasites. Different animal species can only be infected by their own specific species of Plasmodium. Humans are generally host to four species of malaria parasites: Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae. Plasmodium falciparum causes the most dangerous complications, such as cerebral malaria. It is the species that is most virulent and potentially lethal to humans. Because of its dependence on human/vector (mosquito) contact, malaria is considered to be a disease of poverty. Poor people can be physically marginalized and live closer to degraded land and conditions where mosquitoes thrive. They are also less likely to have physical barriers such as screens or nets to protect them and they often lack the education and resources to access proper care and treatment. Intense and costly control programmes targeting malaria, that incorporate a variety of approaches such as environmental modification and indoor spraying with DDT, have succeeded in eliminating or significantly reducing the disease in many countries. Malaria has been eliminated in former Soviet Republics, the USA, Italy, Korea and many Caribbean Islands. The Anopheles gambiae mosquito selects small, sunlit collections of water to lay its eggs. The intact forest provides few such breeding sites so there are few malarious mosquitoes in dark jungles and tropical forests. Replacing tropical forests with agricultural land provides the mosquitoes with the conditions and proximity to human hosts that they require to thrive. Malaria is transmitted by an infected, female mosquito; Anopheles gambiae. It can also be acquired from an infected blood transfusion or even from the shared needles of drug addicts. Human malaria parasites only develop in Anopheles mosquitoes. The parasites move to the salivary glands of the mosquito and are injected into a human host by the feeding insect.
Cause
Human malaria is caused by four different species of the protozoan parasite Plasmodium: Plasmodium falciparum, P. vivax, P. ovale and P. malariae.
Transmission
The malaria parasite is transmitted by various species of Anopheles mosquitoes, which bite mainly between sunset and sunrise
Nature of the disease Malaria is an acute febrile illness with an incubation period of 7 days or longer. Thus, a febrile illness developing less than one week after the first possible exposure is not malaria. The most severe form is caused by P. falciparum, in which variable clinical features include fever, chills, headache, muscular aching and weakness, vomiting, cough, diarrhoea and abdominal pain; other symptoms related to organ failure may supervene, such as: acute renal failure, generalized convulsions, circulatory collapse, followed by coma and death. In endemic areas it is estimated that about 1% of patients with P. falciparum infection die of the disease; the mortality in non-immune travellers with untreated falciparum infection is significantly higher. The initial symptoms, which may be mild, may not be easy to recognize as being due to malaria. It is important that the possibility of falciparum malaria is considered in all cases of unexplained fever starting at any time between the seventh day of first possible exposure to malaria and three months (or, rarely, later) after the last possible exposure. Any individual who experiences a fever in this interval should immediately seek diagnosis and effective treatment, and inform medical personnel of the possible exposure to malaria infection. Early diagnosis and appropriate treatment can be life-saving. Falciparum malaria may be fatal if treatment is delayed beyond 24 hours. A blood sample should be examined for malaria parasites. If no parasites are found in the first blood film while there is clinical suspicion of malaria, a series of blood samples should be taken at 6–12-hour intervals and examined very carefully. Pregnant women, young children and elderly travellers are particularly at risk. Malaria in pregnant travellers increases the risk of maternal death, miscarriage, stillbirth and neonatal death. The forms of malaria caused by other Plasmodium species are less severe and rarely life-threatening. Chemoprophylaxis and treatment of falciparum malaria are becoming more difficult because P. falciparum is increasingly resistant to various antimalarial drugs. Chloroquine resistance of P. vivax is rare and was first reported in the late 1980s in Papua New Guinea and Indonesia. Focal “true” chloroquine resistance (i.e. in patients with adequate blood levels at day of failure) or prophylactic and/or treatment failure have later also been observed in Brazil, Columbia, Ethiopia, Guatemala, Guyana, India, Myanmar, Peru, the Republic of Korea, Solomon Islands, Thailand and Turkey. P. malariae resistant to chloroquine has been reported from Indonesia.
Laboratory tests should be performed and diagnosis of Malaria Disease should be confirmed before any treatment is started. Not doing this should be reserved only for special cases, limiting it to those situations where clear suspicion of a very extreme case is determined and lack of facilities necessitates doing so.
Treatment is determined by three specifications:
1. The species of infecting parasite-this is for three different reasons. a. P. falciparum causes a severe and quickly progressing illness or death, while the other three species rarely are this severe. b. P. Vivax and P. ovale demand treatment for forms that remain dormant and can induce repeat infections. c. P. Falciparum and P. Vivax are known for different resistance levels in different geographic areas where infections occur. For P. Falciparum rapid beginning of treatment is extremely necessary. 2. The physical state of the infected person. 3. The resistance level of the parasites determined by the place the person was when infected. 4. In addition other things to remember about the drug treatment a. Other ailments the patient has. b. Pregnancy c. Drug allergies and sensitivities.
Drugs
Some antimalarial medications can be given intravenously. The usual medications for Malaria are: 1. chloroquine 2.sulfadoxine-pyrimethamine (Fansidar®) 3. mefloquine (Lariam®) 4. atovaquone-proguanil (Malarone®) 5. quinine 6. doxycycline 7. artemisin derivatives (these are usually only available outside the United States).
Cerebral malaria comprises of the clinical reflections of plasmodium falciparum malaria which causes mutations in mental status and sometimes, coma. It is the infection caused by plasmodium falciparum, a protozoan parasite that causes malaria in humans. It is an intense disease of the brain, causing ring-like lesions in the brain, accompanied by fever. The histopathological trademark of this brain disorder is the segregation of cerebral capillaries and venules with parasitized red blood cells (PRBCs) and non-parasitized red blood cells (NPRBCs). The patient should be treated as early as possible, as cerebral malaria gets fatal within 24-72 hours. Cerebral malaria is characterized with retinal whitening, which helps in distinguishing it from other causes of fever. Its risk factors primarily include children below 10 years of age; especially living in malaria-endemic areas.
Cerebral Malaria: Symptoms
Cerebral malaria is the most serious and life-threatening form of malaria, caused by plasmodium falciparum. This species causes chills, persistent high fever, headache, orthostatic hypotension, myalgia and red blood cell (RBC) sludging that leads to capillary blockage at several sites. The three initial stages are: Cold Stage: It ranges from chills to extreme shaking for 1-2 hours Hot Stage: It is characterized by a high fever up to 107°F (41.7°C) for 3-4 hours Wet Stage: It is characterized by profuse sweating for 2-4 hours There are three primary symptoms of cerebral malaria which are common in both adults and children: impaired consciousness with non-specific fever, generalized convulsions and neurological abnormalities, and coma that lasts for 24-72 hours, initially rousable and then unrousable. If not treated on time, it can lead to complications like jaundice, hemoglobinuria, a tender and enlarged spleen, acute renal failure, and uremia, and is fatal in about 20% of patients. Further, it will manifest with signs of increased intracranial pressure, hemiplegia, encephalopathy, delirium, seizures and coma.
Cerebral Malaria: Treatment
Since cerebral malaria gets fatal within a few days of infection, immediate treatment is necessary. The natural immunity to this disease is not very clear but it can be artificially controlled by preventive strategies like antimalarial chemotherapy and adjunctive measures. Chemotherapy for cerebral malaria mainly involves the use of quinine (a bitter alkaloid extracted from chinchona bark), for a patient having chloroquine resistance. It is the only drug which has remained highly effective over a long period of time for treating this disease. Quinine functions similar to chloroquine and interferes with the parasite’s enzymatic digestion. Artemisinin, a clinically proven drug, is known to cure fever and parasitemia faster than chloroquine or quinine. Commonly used by the Chinese as a traditional treatment for fever and malaria, it is a sesquiterpene lactone isolated from the plant Artemisia annua. It is commonly used as artesunate and artemether, and is an important factor in the treatment of multi-drug resistant falciparum malaria. It is cheap and effective, but not yet licensed for use in Europe, North America and Australia.
The use and efficacy of adjunctive measures are debatable. Some of the measures are as follows:
Antipyretics such as paracetamol helps in reducing fever. But, how this diminution in the core temperature benefits the cerebral consequences is not yet clear.
Microcirculatory flow such as pentoxifylline reduces the red cell deformation and blood viscosity. It impairs platelet aggregation and minimizes the systemic vascular resistance, and hence improves the microcirculatory flow.
Anticonvulsants such as phenobarbital sodium is used for seizures. It is necessary to control seizures, as they cause neuronal damage and are linked with fatal outcomes.
Desferrioxamine is an iron chelating adjuvant agent with antimalarial properties. It minimizes the formation of reactive oxygen species by decreasing the amount of free iron.
Cerebral malaria is a severe disease and fatal in many cases. According to the World Health Organization (WHO), it affects nearly 300-500 million people every year, causing over one million deaths, hence having a very high mortality ratio compared to other forms of malaria.
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