PREVENT MALARIA

Prevent Malaria

Preventing Malaria

1. Being aware of the risk

If you are travelling to countries where malaria is common, visit your local clinic for any advice on how to prevent malaria, or you can go to http://www.fitfortravel.nhs.uk/destinations.aspx

2. Preventing Bites

Make sure doors and windows are closed tightly to prevent mosquitoes from entering.

Sleep under an intact mosquito net that has been treated with insecticide or sleep in an air-conditioned room.

Use insect repellant on your skin in sleeping environments. The most effective type is diethyltoluamide.

Stock water bodies such as rivers, ponds, or open canals with fishes to eat the larvae of mosquitoes, or stock it with oil to prevent the larvae from respiring, hence the larvae will eventually die.

3. Anti-malarial tablets

Atovaquone/Proguanil (Malarone): pills taken daily and side effects are uncommon

Chloroquine: pills taken weekly and can be used by pregnant women

Doxcycline: pills taken daily and the cheaper alternative for antimalarial drugs, however it cannot be taken by pregnant women.

(photo: www.flickr.com)

(Centers for Disease Control and Prevention, 2012)

Treating Malaria

Patients who cannot take in oral medication should be given continuous intravenous transfusion. Anti-malarial drugs are usually comprised of prophylactic (preventative) drugs to stop an infection from occurring if a person is bitten by an infected mosquito. Some types of drugs are:

chloroquine

atovaquone-proguanil (Malarone®)

artemether-lumefantrine (Coartem®)

mefloquine (Lariam®)

quinine

quinidine

doxycycline (used in combination with quinine)

clindamycin (used in combination with quinine)

artesunate

In addition to these drugs, primaquine is taken to prevent relapses as it is active against the dormant parasite liver forms (hypnozoites). However, primaquine should not be taken by pregnant women or people who are deficient of glucose-6-phosphate dehydrogenase.

However, in places where anti-malarial drugs have been used widely, strains of drug-resistant Plasmodium have been existent. For example, chloroquine resistance is widespread in parts of South America, Africa, and New Guinea. Because of this resistance, mefloquine is more often used although it is expensive and causes unpleasant side-effects.

Doctors in developed countries tend to misdiagnose malaria as influenza as they rarely see cases of malaria.

(photo: www.flickr.com)

(Cambridge International AS and A Level Biology Coursebook, 2013)

Spread of Malaria

Malaria is endemic in 106 countries. In 2010, 81% cases of Malaria are in Africa which is equivalent to 216 million lives and 90% deaths from Malaria are in Africa which killed a number of 655 thousand lives.

This is due to the disease found mostly throughout the tropics and sub-tropics as in these places, humidity is relatively higher and total annual precipitation is higher. Therefore, there is a higher chance for mosquitoes such as the female Anopheles to reproduce and transmit Malaria in water bodies such ponds, lakes, even in the open sewers of cities.

Malaria can also be spread by blood transfusion, organ transplant, or the shared use of needles or syringes contaminated with blood as the malaria parasite is found in the erythrocytes of the infected person. “Congenital” malaria is a case where the disease is transmitted from the mother to her unborn infant prior or post delivery.

(photo: World Health Organization)

(Cambridge International AS and A Level Biology Coursebook, 2013)

(Centers for Disease Control and Prevention, 2015)

Symptoms

Symptoms appear seven days to a year depending on the parasite a person is infected with. The initial symptoms of malaria are:

fever

headache

sweat

chills

vomiting

The symptoms are mild and difficult to be identified as malaria. With some types of malaria, fever can occur in 48-hour cycles accompanied by severe sweating and fatigue which lasts between 6-12 hours. Other symptoms may include:

muscle pains

diarrhoea

generally feeling unwell

Seek medical advice IMMEDIATELY if you develop symptoms of malaria! Especially if you have visited an area where the disease is commonly found.

(photo: www.reuters.com)

Pathogen

There are over 100 million species of Plasmodium that is known to infect animals such as reptiles, birds, and mammals. Four species of Plasmodium is known to infect humans in nature. In addition, there are some additional species which are able to infect humans exceptionally or under experimental conditions such as on that infects macaques and has been recognised to be a cause of zoonotic malaria in humans.

P. falciparum: found worldwide in tropical and subtropical areas. Approximately 1 million people are killed by this species, especially in Africa where it predominates. P. falciparum can cause severe malaria as it multiplies rapidly in the blood thus causing anemia. The infected parasites are able to clog small blood vessels.

P. vivax: found mostly in Asia, Latin America, and in some parts of Africa. As Asia has one of the largest population densities, P. vivax is probably the most prevalent human malaria parasite. It has dormant liver stages that can activate and invade the blood several months or years after the infecting mosquito bite.

P. ovale: found mostly in Africa (especially West Africa) and the islands of the western Pacific. It is biologically and morphologically very similar to P. vivax; however, it can infect individuals who are negative for the Duffy blood group, which is the case for many residents of sub-Saharan Africa. RBCs that lack the Duffy antigens are relatively resistant to invasion by P. vivax. This explains the greater prevalence of P. ovale in most of Africa.

P. malariae: found worldwide and is the only human malaria parasite species that has a quartan cycle. If untreated, it can cause a long-lasting, chronic infection that in some cases can last a lifetime, and complications such as the nephrotic syndrome.

P. knowlesi: found throughout Southeast Asia as a natural pathogen of long-tailed and pig-tailed macaques. It has shown to be a significant cause of zoonotic malaria in that region. P. knowlesi’s rapid 24-hour replication cycle causes severe infections, even fatal.

(photo: http://www.cdc.gov/dpdx/)

(Centers for Disease Control and Prevention, 2015)

Transmission of Malaria

Most cases of Malaria are caused by the proctoctist Plasmodium.

1. Female Anopheles mosquitoes feed on human blood to obtain the protein they need to develop their eggs.

2. If the person they bite is infected with Plasmodium, they will take up some of the pathogen’s gametes with the blood meal.

3. Male and female gametes fuse in the mosquito’s gut and develop to form infective stages, which move to the mosquito’s salivary glands.

4. When the mosquito feeds again, she injects an anticoagulant from her salivary glands that prevents the blood meal from clotting, so that it flows out of the host into the mosquito.

5. The infective stages pass out into the blood together with the anticoagulant in the saliva, and the parasites enter the red blood cells, where they multiply.

(photo: http://www.anopheles-strasbourg.fr)