Over long weekends, many people like to get out into nature for recreation, whether trekking up a mountain, camping or hiking. But be careful of being bitten by a mosquito carrying various diseases. A case in point is the anopheles mosquito which spreads malaria and lives in forests.
Getting to know malaria
Malaria is caused by a protozoan pathogen called ‘plasmodium’ which lives in the blood. Anopheles mosquitoes are its carriers. There are many types of plasmodium protozoa, but five of them cause disease in humans, namely:
· Plasmodium Falciparum
· Plasmodium Vivax
· Plasmodium Malariae
· Plasmodium Ovale
· Plasmodium Knowlesi
The most common type in Thailand is Plasmodium Falciparum, followed by Plasmodium Vivax.
How is malaria transmitted to humans?
When a malaria-carrying female anopheles mosquito bites a human, it releases sporozoites from its salivary glands into the human bloodstream. It takes about 30 minutes to enter the liver and multiply asexually. This results in thousands of merozoites. The liver cells then grow and burst, releasing the merozoites back into the bloodstream. The organism then travels to erythrocytes and grows into trophozoites and divides again into 6-30 merozoites. Upon hemolysis, the merozoite travels to other erythrocytes in this loop. Some merozoites will change their gender to gametocytes, which are male and female. When a female anopheles mosquito bites a person with a gametocyte in the bloodstream, these bacteria will mate with each other to form a zygote, which develops into an oocyst that implants in the mosquito's stomach. Then it will divide into sporozoites in the salivary glands from where it spreads to humans through mosquito bites.
Types and incubation period of malaria pathogens
Different types of Plasmodium protozoa take different times to divide and produce different red blood cells, for example:
· Plasmodium Falciparum
Found in Thailand and most often in Africa, plasmodium falciparum is the most severe form and can cause death. It takes 42-48 hours to divide, causing fever on the third day after infection.
· Plasmodium Vivax
Found in Thailand and many tropical countries, plasmodium vivax can hide in the liver for years after infection. It takes 48 hours to divide, causing fever on the third day after infection.
· Plasmodium Ovale
Can stay in the liver for years after infection. It takes 48 hours for plasmodium ovale to divide, with fever arising on the third day after infection.
· Plasmodium Malariae
May cause chronic infection. Plasmodium malariae takes 72 hours to divide, giving rise to fever on the fourth day after infection.
· Plasmodium Knowlesi
Can be found frequently in Southeast Asia, including sometimes in Thailand. This type of infection spreads rapidly and becomes chronic. It only takes 24 hours to divide, so fever may occur the day after infection.
Stages of infection
Malaria can be transmitted by an infected mosquito that bites a malarial patient and transmits the infection to other people. However, it cannot be transmitted from person to person directly, other than from mother to fetus. It is also possible to be infected with malaria through blood transfusions and syringe sharing but such cases are rare.
Female Anopheles mosquitoes can bite a malaria-infected person any time that person still has gametocytes in their bloodstream. It can be a source of infection for up to 3 years, or 1-2 years in the case of patients infected with plasmodium falciparum.
Malaria symptoms
Patients infected with malaria begin to develop symptoms from the moment the liver cells begin to mature, rupture and release merozoites into the bloodstream. Initial symptoms are similar to a cold, starting with a low fever and the temperature rising. There will be chills, headache and body and muscle pain. There may also be nausea, loss of appetite, and vomiting. These symptoms can be short term or last several days. It depends on the incubation period of the virus and the number of bacteria the patient has been exposed to. Other severe symptoms include diarrhea, anemia, paleness, yellow eyes and body, bleeding spots or abnormal bleeding, bloody stool, confusion, drowsiness, loss of consciousness and insensitivity to stimuli, and coma.
Fever, the hallmark symptom of malaria, can be divided into three phases:
· First phase – This phase takes 15-60 minutes. It is the hemolysis phase of malaria-infected hemolysis.
o Chill
o Cold
o Rapid pulse
o Spasticity
o Frequent urination
o Gradual rise in body temperature
· Hot phase – This phase takes 1-3 hours.
o Fever over 40 degrees
o Hot body, hot breath, red face, pale mouth
o Thirsty
o Fast and strong pulse
o Headache deep inside the eye socket
· Sweating phase – This phase takes 2-4 hours.
o Fever begins to decrease
o Starting to sweat and returning to normal
How to test for malaria
The doctor will make a diagnosis by taking the patient's history and travel history to see if he/she has traveled to an infected area, usually in the tropics or subtropics in the rainy season. Activities that pose a risk of contracting malaria include hiking, camping and tours in nature involving water sources. In Thailand, the most common outbreak areas are the border areas with neighboring countries.
The doctor will then examine the body and perform a Thick Smear and Thin Smear microscopic blood test. The blood must be stained to reveal any infection with giemsa, so that the doctor can determine the appropriate treatment. The doctor may also use other tests to help determine the type of protozoan infection, including:
· Liver function test
· Complete Blood Count (CBC)
· Blood sugar test
· Gene testing (very expensive and not popular in Thailand)
· Examination by blood staining and microscopic examination
· Rabies antigen detection kits (RDT) which are available but are quite expensive and not commonly used in Thailand
· Microscopy
Malaria treatment
Malaria can be cured if treated promptly. The doctor will divide the treatment into three types:
· Specific treatment
Specific treatment involves administration of ‘schizontocide’ to eradicate malaria in the asexual stage in red blood cells by administering a drug called Schizontocide. It is necessary to consider the characteristics of drug resistance of malaria in different areas. Use of other drugs may also be considered, taking into account factors such as the type of infection, severity of symptoms, the patient’s age, and pregnancy. Antimalarial drugs commonly used include:
o Chloroquine
o Doxycycline
o Quinine Sulfate
o Hydroxychloroquine
o Mefloquine
o Primaquine
o Combination of Proguanil and Atovaquone
o Combination of Artemether and Lumefantrine
· Treatment of symptoms and complications
Symptoms and complications should be treated while the patient is still infected with malaria or after the infection is gone, especially those infected with plasmodium fuzziparum. Delay can lead to serious complications.
· Preventing the spread of disease
We can prevent the spread of infection by using a drug called Gametocytocide which kills infectious malaria with gametocyte, especially in patients living in mosquito-borne areas.
How can malaria be prevented?
Although there is a World Health Organization (WHO)-approved malaria vaccine, it is only used in malaria-prone countries such as in Africa. However, if we have to travel to malaria endemic areas, we can protect ourselves as follows:
· Wear light-colored clothing and cover our body completely.
· Use insect repellents such as Diethyltoluamide (DEET) available in spray, roll-on, stick and cream forms. It may need to be reapplied frequently for effective protection but it should not be used with young children.
· Sleep under a mosquito net or in a mosquito-free area. Use mosquito nets impregnated with mosquito repellents to increase the protection.
· Get rid of and avoid larval sources such as stagnant water areas.
Now you understand more about malaria, next time you go travelling, don't forget to prepare yourself with clothes and mosquito repellent. That way you will be able to travel safely and have peace of mind. However, if you have symptoms that could be malaria, you should see a doctor for a check-up and receive timely treatment.
Krungthai-AXA Life Insurance customers interested in health care can check out other health articles at https://www.krungthai-axa.co.th/th/health-advisories.
References
· Faculty of Tropical Medicine, Mahidol University
https://www.tropmedhospital.com/knowledge/malaria.html
· Siriraj Piyamaharajkarun Hospital
https://www.siphhospital.com/th/news/article/share/573
· Vibhavadi Hospital
https://www.vibhavadi.com/Health-expert/detail/562
· Corporate Communication, Faculty of Medicine, Ramathibodi Hospital
https://bit.ly/3CpQHT7
· Pobpad website
https://bit.ly/3jSXuyh
· Princ Hospital Suvarnabhumi
https://www.princsuvarnabhumi.com/content-malaria/
· King Chulalongkorn Memorial Hospital, the Thai Red Cross Society
https://bit.ly/3GkUqCp
https://bit.ly/3ZdkGYd
