PARASITICAL DISEASE -MALARIA
Malaria is a parasitical disease. It is transmitted from infected person to normal person through anopheles group of mosquitoes. Disease generally starts with mild fever and flue like symptoms, gradually increase fever chill and tiredness, headache and vomiting. In severe cases, it can cause coma or death. Symptoms usually begin ten to fifteen days after being bitten by an infected mosquito.
Malaria is caused by Plasmodium group of parasites. It is spread through infected mosquitoes.
The mosquito bite introduces the parasites from its saliva into a person’s blood.
Then the parasites slowly travel to the liver where they mature and reproduce. Species of Plasmodium can infect to the Red Blood Cells.
Plasmodium group of parasites are:
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae.
Most of the death by Malaria are caused by Plasmodium falciparum. Other group of malarial Parasites (Plasmodium vivax, Plasmodium ovale and plasmodium malariae) generally cause a milder effect than falciparum.
Malaria is usually diagnosed by laboratory examination of blood films, and with antigen based rapid diagnostic test.
Methods that use the PCR (polymerase chain reaction) detect the parasite’s DNA have been developed, but are not widely used due to their cost and complexity.
Treatment
The recommended treatment for malaria is a combination of antimalarial medications. The types of drugs and period of treatment may vary depending on type of malarial parasite.
Chloroquine phosphate.
Artemisinin-based combination therapies.
Quinine sulphate with doxycycline.
Prevention
Preventing mosquito bites with mosquito nets.
Insect repellents.
Spraying insecticides.
Draining standing water.
Several medications are available to prevent malaria for travelers in areas where the disease is common.
In 2020, there is one vaccine which has been shown to reduce the risk of malaria by about 40% in children. Efforts to develop more effective vaccines are ongoing.
Life cycle of Malarial Parasite
Infected Anopheles mosquito introduced sporozoites. These parasite follow the bloodstream to the liver where they invade hepatocytes. Then they grow and divide in the liver. It takes 2-10 days. Each infected hepatocyte harboring 30,000 – 40,000 parasites.
Then hepatocytes break down and releasing form (Plasmodium- merozoites) into the blood stream. These merozoites invade red blood cells. Then they started replicating. It takes 2 to3 days.
The infected red blood cell lyses, and the new merozoites infect new red blood cells. This cycle continuously increased the number of parasites in an infected patient.
During the cycle, a small number of parasites do not replicate. They develop into male and female Gametocytes.
These gametocytes develop in the Bone marrow, then return to the blood circulation. Then they are taken by the bite of another mosquito.
Once inside a mosquito, the gametocytes undergo sexual reproduction and form daughter sporozoites that migrate to the mosquito’s salivary glands. Then infects a new host by the mosquito bites.
Diagnosis:
Malaria diagnosis is typically suspected based on symptoms and travel history, then confirmed with a blood 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 °C without any other obvious cause.
Malaria should similarly be suspected in children with signs of anaemia, pale palms.
Malaria is usually confirmed by the microscopic examination of blood films or by antigen-based rapid diagnostic tests (RDT). Microscopy – Examining stained blood smear with microscope for malaria diagnosis.
In places where microscopy is unavailable, malaria is diagnosed by rapid antigen tests (RDT) that detect parasite.
RDTs are targeting the parasite proteins histidine rich protein (HRP2, detects P. falciparum only) lactate dehydrogenase or aldolase. The HRP2 test is widely used in Africa, where Plasmodium falciparum predominates.
Classification:
Malaria is classified into either “severe” or “uncomplicated” by the (WHO). It is considered severe when any of the following criteria are present, otherwise it is considered uncomplicated.
- Decreased consciousness
- Weakness such that the person is unable to walk.
- Inability to feed.
- Two or more convulsions.
- Low Blood pressure (less than 70 mm Hg in adults and 50 mmHg in children).
- Breathing Problems.
- Shock.
- Kidney Failure or haemoglobin in the urine.
- Bleeding problems, or haemoglobin less than 5.0 g/dL.
- Blood glucose level less than 40 mg/dL.
Cerebral malaria is defined as a severe Plasmodium falciparum-malaria presenting with neurological symptoms.