Are Mosquitoes That Carry Malaria Parasites Also Affected? В» Science ABC

Are Mosquitoes That Carry Malaria Parasites Also Affected?

You may already know that malaria, one of the deadliest diseases on Earth, killing millions of humans every year, is an infectious disease transmitted by mosquitoes. Not only does this disease mess with humans, but it also affects a number of other vertebrates. Mosquito bites introduce the malaria parasite into a person’s blood, and within a fortnight or so, the initial symptoms of malaria begin to appear.

Many people don’t realize that it’s not the mosquito that synthesizes the malaria parasite; instead, a mosquito is just a vector, a medium that aids the transmission of the malaria parasite to a human host. So, theoretically, one could say that the malaria parasite enters the body of the mosquito first, and is subsequently ‘delivered’ to a human following a mosquito bite.

Malaria parasites are delivered to human hosts following mosquito bites.(Photo Credit : Pixabay)

Following that line of reasoning, is it possible that the malaria parasite affects the mosquito who carries it? In other words, are mosquitoes that carry malaria parasites harmed by them? Do mosquitoes also contract diseases from malaria parasites, just like humans?

In order to answer that, it helps to first understand how malaria actually works.

What causes malaria?

If you paid attention during your biology class in high school, or maybe the health and fitness awareness campaigns that were conducted in your school, housing society or even workplace, then you surely know that malaria is caused by mosquitoes. But how exactly does that happen?

For the uninitiated, malaria is caused by a type of single-celled parasite called Plasmodium. More specifically, Plasmodium is a genus of parasitic alveolates, many of which are known to cause malaria in their hosts.

Trophozoites of the Plasmodium vivax parasite among human red blood cells (Photo Credit : PHIL_2720_lores / Wikimedia Commons)

Malaria parasites

Although there are more than 100 known species of Plasmodium, which are known to affect various animal species, including birds, reptiles and many other mammals, 4-5 species of Plasmodium have long been known to infect humans. These include P. falciparum, P. malariae, P. ovale, P. vivax and P. knowles. All these species of Plasmodium are found in different parts of the world and grow and spread in different climatic conditions.

It works this way: one of the aforementioned malaria parasites are transmitted by female Anopheles (a species of mosquitoes particularly notorious for spreading malaria), which bites primarily between dusk and dawn.

Female Anopheles mosquito (Photo Credit :

You see, female mosquitoes need to take blood to make ‘meals’ and carry out their egg production. These ‘blood meals’ are the primary link between humans and the mosquito hosts in the parasite’s life cycle.

Once the parasite enters the body of the mosquito, its development from the “gametocyte” stage to the “sporozoite” stage depends on a few factors, the most critical of which include ambient temperature (higher temperatures accelerate the malaria parasite growth in the mosquito), humidity, and whether the Anopheles survives long enough to allow the parasite to complete its cycle (which lasts around 10 to 18 days).

Does the mosquito host get affected by the malaria parasite?

Yes, a mosquito host does get affected by the malaria parasite. Only, not in the same way as a human host does.

As it turns out, mosquitoes infected by malaria parasites seem to suffer the fitness costs of carrying those parasites. This, in a way, could mean that mosquitoes are also negatively affected by malaria parasites.

A study published back in 2010 showed that Plasmodium-infected mosquitoes had about half as many offspring as their non-infected counterparts, as malaria parasites are known to affect the fecundity (i.e., the ability to produce an abundance of offspring or new growth) of several species of mosquitoes. In this study, the reproductive fitness of female Anopheles gambiae feeding on an infected blood meal was tested, and it was observed that the total number of eggs produced were reduced by 41.2%!

The reproductive abilities of female Anopheles mosquitoes are affected by certain malaria parasites.(Photo Credit : Anest / Shutterstock)

Another study showed that the mosquitoes that were genetically manipulated to be resistant to a particular malaria parasite (P. berghei, a protozoan parasite that causes malaria in certain rodents) performed better than normal mosquitoes when feeding on infected prey.

This is a good thing, as the introduction of genes that impair Plasmodium development in mosquito populations can turn out to be a fitness advantage for mosquitoes, leading to an effective malaria control strategy by means of the genetic modification of mosquitoes.

In a nutshell, yes, mosquitoes are certainly affected by malaria parasites that they carry, but not in the same way as humans are.


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Infection with malaria parasites may result in a wide variety of symptoms, ranging from absent or very mild symptoms to severe disease and even death. Malaria disease can be categorized as uncomplicated or severe (complicated). In general, malaria is a curable disease if diagnosed and treated promptly and correctly.

All the clinical symptoms associated with malaria are caused by the asexual erythrocytic or blood stage parasites. When the parasite develops in the erythrocyte, numerous known and unknown waste substances such as hemozoin pigment and other toxic factors accumulate in the infected red blood cell. These are dumped into the bloodstream when the infected cells lyse and release invasive merozoites. The hemozoin and other toxic factors such as glucose phosphate isomerase (GPI) stimulate macrophages and other cells to produce cytokines and other soluble factors which act to produce fever and rigors and probably influence other severe pathophysiology associated with malaria.

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Plasmodium falciparum-infected erythrocytes, particularly those with mature trophozoites, adhere to the vascular endothelium of venular blood vessel walls and do not freely circulate in the blood. When this sequestration of infected erythrocytes occurs in the vessels of the brain it is believed to be a factor in causing the severe disease syndrome known as cerebral malaria, which is associated with high mortality.

Following the infective bite by the Anopheles mosquito, a period of time (the “incubation period”) goes by before the first symptoms appear. The incubation period in most cases varies from 7 to 30 days. The shorter periods are observed most frequently with P. falciparum and the longer ones with P. malariae.

Antimalarial drugs taken for prophylaxis by travelers can delay the appearance of malaria symptoms by weeks or months, long after the traveler has left the malaria-endemic area. (This can happen particularly with P. vivax and P. ovale, both of which can produce dormant liver stage parasites; the liver stages may reactivate and cause disease months after the infective mosquito bite.)

Such long delays between exposure and development of symptoms can result in misdiagnosis or delayed diagnosis because of reduced clinical suspicion by the health-care provider. Returned travelers should always remind their health-care providers of any travel in areas where malaria occurs during the past 12 months.

The classical (but rarely observed) malaria attack lasts 6–10 hours. It consists of

  • A cold stage (sensation of cold, shivering)
  • A hot stage (fever, headaches, vomiting; seizures in young children); and
  • Finally a sweating stage (sweats, return to normal temperature, tiredness).

Classically (but infrequently observed) the attacks occur every second day with the “tertian” parasites (P. falciparum, P. vivax, and P. ovale) and every third day with the “quartan” parasite (P. malariae).

More commonly, the patient presents with a combination of the following symptoms:

  • Fever
  • Chills
  • Sweats
  • Headaches
  • Nausea and vomiting
  • Body aches
  • General malaise

In countries where cases of malaria are infrequent, these symptoms may be attributed to influenza, a cold, or other common infections, especially if malaria is not suspected. Conversely, in countries where malaria is frequent, residents often recognize the symptoms as malaria and treat themselves without seeking diagnostic confirmation (“presumptive treatment”).
Physical findings may include the following:

  • Elevated temperatures
  • Perspiration
  • Weakness
  • Enlarged spleen
  • Mild jaundice
  • Enlargement of the liver
  • Increased respiratory rate

Diagnosis of malaria depends on the demonstration of parasites in the blood, usually by microscopy. Additional laboratory findings may include mild anemia, mild decrease in blood platelets (thrombocytopenia), elevation of bilirubin, and elevation of aminotransferases.
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Severe malaria occurs when infections are complicated by serious organ failures or abnormalities in the patient’s blood or metabolism. The manifestations of severe malaria include the following:

  • Cerebral malaria, with abnormal behavior, impairment of consciousness, seizures, coma, or other neurologic abnormalities
  • Severe anemia due to hemolysis (destruction of the red blood cells)
  • Hemoglobinuria (hemoglobin in the urine) due to hemolysis
  • Acute respiratory distress syndrome (ARDS), an inflammatory reaction in the lungs that inhibits oxygen exchange, which may occur even after the parasite counts have decreased in response to treatment
  • Abnormalities in blood coagulation
  • Low blood pressure caused by cardiovascular collapse
  • Acute kidney injury
  • Hyperparasitemia, where more than 5% of the red blood cells are infected by malaria parasites
  • Metabolic acidosis (excessive acidity in the blood and tissue fluids), often in association with hypoglycemia
  • Hypoglycemia (low blood glucose). Hypoglycemia may also occur in pregnant women with uncomplicated malaria, or after treatment with quinine.

Severe malaria is a medical emergency and should be treated urgently and aggressively.

In P. vivax and P. ovale infections, patients having recovered from the first episode of illness may suffer several additional attacks (“relapses”) after months or even years without symptoms. Relapses occur because P. vivax and P. ovale have dormant liver stage parasites (“hypnozoites”) that may reactivate. Treatment to reduce the chance of such relapses is available and should follow treatment of the first attack.

Mosquito Malaria Vectors

The mosquito has been described as the most dangerous animal in the world and the mosquito-borne disease with the greatest detrimental impact is undoubtedly malaria.

Anopheles stephensi in flight © Hugh Sturrock, Wellcome Images

There are about 3,500 mosquito species and those that transmit malaria all belong to a sub-set called the Anopheles. Approximately 40 Anopheles species are able to transmit malaria well enough to cause significant human illness and death.

To be effective at transmitting malaria between people, a mosquito species needs to have a number of characteristics including:

  • Abundance – the species needs to exist in numbers high enough to ensure individuals encounter an infectious human to pick up the malaria parasite
  • Longevity – individual mosquitoes need to survive long enough after feeding on infected blood to allow the parasite time to develop and travel to the mosquito’s salivary glands ready to infect the next person bitten
  • Capacity – each mosquito needs to be able to carry enough malaria parasites in the salivary glands to ensure the parasite is transmitted to the next human
  • Contact with humans – the species needs to prefer to feed on humans rather than other animals, and be able to survive and breed in places close to homes, and be able to find people (usually by entering their houses)

The information that tells us whether a mosquito species is likely to be an effective carrier (vector) of the malaria parasite is its bionomics.

Malaria mosquito — an excursion into the life of a carrier of a dangerous disease

Malaria is a potentially fatal blood disease caused by a parasite that is transmitted to human and animal hosts by the Anopheles mosquito. The human parasite, Plasmodium falciparum, is dangerous not only be cause it digests the red blood cell’s hemoglobin, but also because it changes the adhesive properties of the cell it inhabits. This change in turn causes the cell to stick to the walls of blood vessels. It becomes especially dangerous when the infected blood cells stick to the capillaries in the brain, obstructing blood flow, a condition called cerebral malaria. Scientists using the x-ray microscope are hoping to learn more about the how the parasite infects and disrupts the blood cells and the blood vessels of an infected host.

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The Life Cycle of the Malaria Parasite

The life cycle of the malaria parasite in a human or animal begins when an infected mosquito transmits malaria sporozoites to a new host. The sporozoites travel to the liver, where they invade hepatocytes (liver cells) and multiply thousands of times over the following two weeks before rupturing out of the liver into the blood stream. During the first 48 hours after infecting a red blood cell, a parasite goes through several phases of development . The first phase is the ring stage, in which the parasite begins to metabolize hemoglobin. The next phase is the trophozoite stage, during which the parasite metabolizes most of the hemoglobin, gets larger, and prepares to reproduce more parasites. Finally, the parasite divides asexually to form a multinucleated schizont. At the end of the cycle, the red blood cell bursts open and the parasites are dispersed to infect more red blood cells.

Symptoms of Typhoid and Malaria Fever

A lot of dangerous illnesses can go unrecognized for a long period of time. Are you a carrier of the bacteria that causes such life-threatening diseases as malaria and typhoid fever? What are the symptoms of these two illnesses? Check out this list to be sure you have no symptoms or get medical help if you believe you are in danger. Make sure your children and friends are also safe. It is definitely better to take care of your health before it becomes too late, isn’t it?

Each year over 20 million people get typhoid and over 200 million patients suffer from malaria globally. These diseases go along with international travelers so no one is 100% protected from meeting someone who carries the infection. It is important to know the typical symptoms of typhoid and malaria and pay close attention to how you feel throughout the day. High fever, vomiting, and gastrointestinal issues are just some of the symptoms you must consider.

What are Typhoid and Malaria Fever?

Any illness can be dangerous if you don’t take care of it in time. Typhoid fever can be just as dangerous as malaria. The question is how quickly you realize you are ill and need to see the doctor. So what is typhoid fever? What is malaria? Why is it so important to be attentive to all the symptoms of these diseases?

Typhoid fever is spread through food and drinks that contain Salmonella paratyphi or Typhi bacteria. If a person drinks a glass of infected water, forgets to wash hands after a visit to the toilet or eats infected meals, there is a higher chance that he or she will be also infected with typhoid fever illness.

As for malaria, this dangerous disease is transmitted by mosquitoes. The bite of an infected mosquito releases the dangerous parasite into the human blood. This is how blood cells are infected. If you don’t get medical help, your red blood cells can be destroyed by the illness. Malaria causes hundreds of thousands of death annually. This is a common disease in Africa. It is extremely dangerous for little kids although it can be also fatal for adults.

Symptoms of Typhoid

The list of typhoid symptoms is not too long. You just have to be very attentive to your health and be concerned if you experience most of these medical issues:

  • loss of appetite
  • severe, regular or random headaches
  • high fever of 39 and even over 40 degrees Celsius (this is approximately 104 degrees Fahrenheit)
  • stomach pains
  • unexpected aches and rash
  • diarrhea
  • vomiting
  • blood in urine
  • extreme tiredness and lack of energy
  • confusion
  • excess sweating
  • dry cough
  • sudden weight loss

Typhoid is a dangerous illness. It can lead to extremely high fever. It can cause severe diarrhea. It can also lead to vomiting. These are dangerous symptoms and they can be fatal if you do not get medical help as soon as possible.

The symptoms are usually noticeable on the 6th – 30th day from the moment the person is exposed to the bacteria.

Symptoms of Malaria

The bites of mosquitoes can threaten human life. The symptoms of malaria are similar to flu:

  • strong headache
  • muscle pain
  • nausea
  • sudden chills
  • diarrhea
  • vomiting
  • lack of energy throughout the day
  • bloody stool

While some of the symptoms might not sound too dangerous, patients who do not get treated in time can suffer severe consequences. Malaria can sometimes cause problems with breathing, low hemoglobin levels, and even coma.

You will notice that malaria and typhoid symptoms are non-specific. They can be easily mistaken and mixed up with other diseases. Only clinical tests and medical diagnosis of the symptoms can specify which illness you have.

Such symptoms as fever, sudden aches, vomiting, and diarrhea require medical treatment even if you are sure that you don’t have malaria or typhoid. These are dangerous signs that require your attention.

Don’t play games with your health. Both typhoid and malaria can be medically treated and patients achievevfull recovery. Don’t hesitate to contact your doctor if you notice one or more of the symptoms of these illnesses. Get medical help at once and stay positive, healthy, and happy.

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What to know about malaria

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Malaria is a life-threatening mosquito-borne blood disease. The Anopheles mosquito transmits it to humans

The parasites in mosquitos that spread malaria belong to the Plasmodium genus. Over 100 types of Plasmodium parasite can infect a variety of species. Different types replicate at different rates, changing how quickly the symptoms escalate, and the severity of the disease.

Five types of Plasmodium parasite can infect humans. These occur in different parts of the world. Some cause a more severe type of malaria than others.

Once an infected mosquito bites a human, the parasites multiply in the host’s liver before infecting and destroying red blood cells.

In some places, early diagnosis can help treat and control malaria. However, some countries lack the resources to carry out effective screening.

Currently, no vaccine is available for use in the United States, although one vaccine has a license in Europe.

In the early 1950s, advances in treatment eliminated malaria from the U.S. However, between 1,500 and 2,000 cases still occur each year, mostly in those who have recently traveled to malaria-endemic areas.

Doctors divide malaria symptoms into two categories: Uncomplicated and severe malaria.

Uncomplicated malaria

Share on Pinterest Malaria is passed on by the Anopheles mosquito.

A doctor would give this diagnosis when symptoms are present, but no symptoms occur that suggest severe infection or dysfunction of the vital organs.

This form can become severe malaria without treatment, or if the host has poor or no immunity.

Symptoms of uncomplicated malaria typically last 6 to 10 hours and recur every second day.

Some strains of the parasite can have a longer cycle or cause mixed symptoms.

As symptoms resemble those of flu, they may remain undiagnosed or misdiagnosed in areas where malaria is less common.

In uncomplicated malaria, symptoms progress as follows, through cold, hot, and sweating stages:

  • a sensation of cold with shivering
  • fever, headaches, and vomiting
  • seizures sometimes occur in younger people with the disease
  • sweats, followed by a return to normal temperature, with tiredness

In areas where malaria is common, many people recognize the symptoms as malaria and treat themselves without visiting a doctor.

Severe malaria

In severe malaria, clinical or laboratory evidence shows signs of vital organ dysfunction.

Symptoms of severe malaria include:

  • fever and chills
  • impaired consciousness
  • prostration, or adopting a prone position
  • multiple convulsions
  • deep breathing and respiratory distress
  • abnormal bleeding and signs of anemia
  • clinical jaundice and evidence of vital organ dysfunction

Severe malaria can be fatal without treatment.

Treatment aims to eliminate the Plasmodium parasite from the bloodstream.

Those without symptoms may be treated for infection to reduce the risk of disease transmission in the surrounding population.

The World Health Organization (WHO) recommends artemisinin-based combination therapy (ACT) to treat uncomplicated malaria.

Artemisinin is derived from the plant Artemisia annua, better known as sweet wormwood. It rapidly reduces the concentration of Plasmodium parasites in the bloodstream.

Practitioners often combine ACT with a partner drug. ACT aims to reduce the number of parasites within the first 3 days of infection, while the partner drugs eliminate the rest.

Expanding access to ACT treatment worldwide has helped reduce the impact of malaria, but the disease is becoming increasingly resistant to the effects of ACT.

In places where malaria is resistant to ACT, treatment must contain an effective partner drug.

The WHO has warned that no alternatives to artemisinin are likely to become available for several years.

There are several ways to keep malaria at bay.


Research to develop safe and effective global vaccines for malaria is ongoing, with the licensing of one vaccine already having occurred in Europe. No vaccine is yet licensed in the U.S.

Seek medical attention for suspected symptoms of malaria as early as possible.

Advice for travelers

While malaria is not endemic to the U.S., travel to many countries around the world entails a risk.

The Centers for Disease Control advise travelers to take the following precautions:

  • find out what the risk of malaria is in the country and city or region they are visiting
  • ask their doctor what medications they should use to prevent infection in that region
  • obtain antimalarial drugs before leaving home, to avoid the risk of buying counterfeit drugs while abroad
  • consider the risk for individual travelers, including children, older people, pregnant women, and the existing medical conditions of any travelers
  • ensure they will have access to preventative tools, many of which are available to purchase online, including insect repellants, insecticides, pre-treated bed nets, and appropriate clothing
  • be aware of the symptoms of malaria

In emergency situations, local health authorities in some countries may carry out “fogging,” or spraying areas with pesticides similar to those used in household sprays.

The WHO points out that these are not harmful for people, as the concentration of pesticide is only strong enough to kills mosquitoes.

While away, travelers should, where possible, avoid situations that increase the risk of being bitten by mosquitoes. Precautions include taking an air-conditioned room, not camping by stagnant water, and wearing clothes that cover the body at times when mosquitoes are most likely to be around.

For a year after returning home, the traveler may be susceptible to symptoms of malaria. Donating blood may also not be possible for some time.

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