Why do mosquitoes carry malaria

Many species prefer habitats with vegetation. Others prefer habitats that have none. Some breed in open, sun-lit pools while others are found only in shaded breeding sites in forests. A few species breed in tree holes or the leaf axils of some plants. The pupa is comma-shaped when viewed from the side. This is a transitional stage between larva and adult. The pupae does not feed, but undergoes radical metamorphosis.

The head and thorax are merged into a cephalothorax with the abdomen curving around underneath. As with the larvae, pupae must come to the surface frequently to breathe, which they do through a pair of respiratory trumpets on the cephalothorax. After a few days as a pupa, the dorsal surface of the cephalothorax splits and the adult mosquito emerges onto the surface of the water.

The duration from egg to adult varies considerably among species and is strongly influenced by ambient temperature. Mosquitoes can develop from egg to adult in as little as 7 days but usually take days in tropical conditions. Anopheles Adults. Note bottom row the typical resting position. Like all mosquitoes, adult anopheles have slender bodies with 3 sections: head, thorax and abdomen.

The head is specialized for acquiring sensory information and for feeding. The head contains the eyes and a pair of long, many-segmented antennae. The antennae are important for detecting host odors as well as odors of aquatic larval habitats where females lay eggs. The head also has an elongate, forward-projecting proboscis used for feeding, and two sensory palps. The thorax is specialized for locomotion. Three pairs of legs and a single pair of wings are attached to the thorax.

The abdomen is specialized for food digestion and egg development. This segmented body part expands considerably when a female takes a blood meal. The blood is digested over time serving as a source of protein for the production of eggs, which gradually fill the abdomen.

Anopheles mosquitoes can be distinguished from other mosquitoes by the palps, which are as long as the proboscis, and by the presence of discrete blocks of black and white scales on the wings. Adult Anopheles can also be identified by their typical resting position: males and females rest with their abdomens sticking up in the air rather than parallel to the surface on which they are resting. Adult mosquitoes usually mate within a few days after emerging from the pupal stage.

In some species, the males form large swarms, usually around dusk, and the females fly into the swarms to mate. The mating habitats of many species remain unknown. Males live for about a week, feeding on nectar and other sources of sugar.

Females will also feed on sugar sources for energy but usually require a blood meal for the development of eggs. After obtaining a full blood meal, the female will rest for a few days while the blood is digested and eggs are developed. This process depends on the temperature but usually takes days in tropical conditions. Once the eggs are fully developed, the female lays them then seeks blood to sustain another batch of eggs.

The cycle repeats itself until the female dies. Females can survive up to a month or longer in captivity but most do not live longer than weeks in nature. Their chances of survival depend on temperature and humidity, but also upon their ability to successfully obtain a blood meal while avoiding host defenses.

Understanding the biology and behavior of Anopheles mosquitoes can aid in designing appropriate control strategies. Long-lived species that prefer human blood and support parasite development are the most dangerous. Factors that should be taken into consideration when designing a control program include the susceptibility of malaria mosquitoes to insecticides and the preferred feeding and resting location of adult mosquitoes.

One important behavioral factor is the degree to which an Anopheles species prefers to feed on humans anthropophily or animals such as cattle zoophily. Anthrophilic Anopheles are more likely to transmit the malaria parasites from one person to another.

Most Anopheles mosquitoes are not exclusively anthropophilic or zoophilic; many are opportunistic and feed upon whatever host is available. However, the primary malaria vectors in Africa, An. Once ingested by a mosquito, malaria parasites must undergo development within the mosquito before they are infectious to humans.

The time required for development in the mosquito the extrinsic incubation period takes 9 days or longer, depending on the parasite species and the temperature. If a mosquito does not survive longer than the extrinsic incubation period, then she will not be able to transmit any malaria parasites.

It is not possible to measure directly the life span of mosquitoes in nature, but many studies have indirectly measured longevity by examination of their reproductive status or via marking, releasing, and recapturing adult mosquitoes. The majority of mosquitoes do not live long enough to transmit malaria, but some may live as long as three weeks in nature. Though evidence suggests that mortality rate increases with age, most workers estimate longevity in terms of the probability that a mosquito will live one day.

Usually these estimates range from a low of 0. Any control measure that reduces the average lifespan of the mosquito population will reduce transmission potential. Insecticides thus need not kill the mosquitoes outright, but may be effective by limiting their lifespan. Most Anopheles mosquitoes are crepuscular active at dusk or dawn or nocturnal active at night. Some Anopheles mosquitoes feed indoors endophagic while others feed outdoors exophagic.

After blood feeding, some Anopheles mosquitoes prefer to rest indoors endophilic while others prefer to rest outdoors exophilic. Biting by nocturnal, endophagic Anopheles mosquitoes can be markedly reduced through the use of insecticide-treated bed nets ITNs or through improved housing construction to prevent mosquito entry e. Endophilic mosquitoes are readily controlled by indoor spraying of residual insecticides.

Insecticide-based control measures e. Zhiyong Xi at Michigan State University set out to establish a stable, inherited Wolbachia infection that could block Plasmodium growth in Anopheles.

Results appeared on May 10, , in Science. The researchers injected a strain of Wolbachia derived from another type of mosquito into A. Once matured, the adult females mated with uninfected male mosquitoes to create a stable Wolbachia infection that persisted for 34 generations the end of the study period. Uninfected females rarely produced viable eggs with infected males.

To see how well the infected mosquitoes could invade an uninfected A. The researchers found that Wolbachia infection reduced the number of malaria parasites in both the mosquito midgut and salivary glands. They hypothesize that Wolbachia infection causes the formation of unstable compounds known as reactive oxygen species, which inhibit parasite development. Several good antimalarial drugs are available, and should be taken early on. The most important step is to go see a doctor if you are sick and are presently in, or have recently been in, an area with malaria, so that the disease is diagnosed and treated right away.

Malaria can be cured with prescription drugs. The type of drugs and length of treatment depend on the type of malaria, where the person was infected, their age, whether they are pregnant, and how sick they are at the start of treatment. Very rarely. Travelers who are taking effective malaria preventive drugs but who will be traveling for an extended period of time or who will be at higher risk of developing a malaria infection may decide, in consultation with their health-care provider, to take along malaria treatment medication referred to as a reliable supply in case they develop malaria while traveling.

If the traveler develops symptoms of malaria, they should immediately seek medical attention so that they can be examined and diagnosed appropriately. If they are diagnosed with malaria, they will then already have with them a reliable supply of an effective malaria treatment medicine to take.

Malaria self-treatment should begin right away if fever, chills, or other influenza-like illness symptoms occur and if professional medical care is not available within 24 hours. Self-treatment of a possible malarial infection is only a temporary measure and immediate medical care is important. No, not necessarily. Malaria can be treated.

If the right drugs are used, people who have malaria can be cured and all the malaria parasites can be cleared from their body. However, the disease can continue if it is not treated or if it is treated with the wrong drug.

Some drugs are not effective because the parasite is resistant to them. Some people with malaria may be treated with the right drug, but at the wrong dose or for too short a period of time. Two types species of parasites, Plasmodium vivax and P. People diagnosed with P.

Another type of malaria, P. However, in general, if you are correctly treated for malaria, the parasites are eliminated and you are no longer infected with malaria. Malaria typically is found in warmer regions of the world — in tropical and subtropical countries.

Higher temperatures allow the Anopheles mosquito to thrive. Malaria parasites, which grow and develop inside the mosquito, need warmth to complete their growth before they are mature enough to be transmitted to humans. Malaria occurs in more than countries and territories. Yet malaria does not occur in all warm climates. For example, malaria has been eliminated in some countries with warm climates, while a few other countries have no malaria because Anopheles mosquitoes are not found there.

In Africa south of the Sahara, the principal malaria mosquito, Anopheles gambiae , transmits malaria very efficiently. The type of malaria parasite most often found, Plasmodium falciparum , causes severe, potentially fatal disease.

Lack of resources and political instability can prevent the building of solid malaria control programs. In addition, malaria parasites are increasingly resistant to antimalarial drugs, presenting one more barrier to malaria control on that continent. What constitutes a rural area can vary by country. In general, urbanization can be said to involve both population size and economic development of an area in which there is concentrated commercial activity, such as manufacturing, the sale of goods and services, and transportation.

Rural areas tend to have less commercial activity, less population density, more green space, and agriculture may be a main feature. Eradication means that no more malaria exists in the world. Malaria has been eliminated from many developed countries with temperate climates. However, the disease remains a major health problem in many developing countries, in tropical and subtropical parts of the world.

Malaria can also be spread through blood transfusions and the sharing of needles, but this is very rare. Page last reviewed: 22 August Next review due: 22 August There are many different types of plasmodium parasite, but only 5 types cause malaria in humans. These are: Plasmodium falciparum — mainly found in Africa, it's the most common type of malaria parasite and is responsible for most malaria deaths worldwide Plasmodium vivax — mainly found in Asia and South America, this parasite causes milder symptoms than Plasmodium falciparum, but it can stay in the liver for up to 3 years, which can result in relapses Plasmodium ovale — fairly uncommon and usually found in West Africa, it can remain in your liver for several years without producing symptoms Plasmodium malariae — this is quite rare and usually only found in Africa Plasmodium knowlesi — this is very rare and found in parts of southeast Asia How malaria is spread The plasmodium parasite is spread by female Anopheles mosquitoes, which are known as "night-biting" mosquitoes because they most commonly bite between dusk and dawn.