Malaria is a mosquito-borne blood disease that is life-threatening. The Anopheles mosquito transmits it to humans.
The Plasmodium genus belongs to the parasites of mosquitoes that spread malaria. More than 100 types of parasite Plasmodium can infect a variety of species. Different forms propagate at different levels, affecting how quickly the symptoms intensify and disease severity.
Five types of parasite Plasmodium can infect humans. These occur in different parts of the world. Some cause malaria in a more extreme form than others.
When a person is bitten by an infected mosquito, the parasites multiply in the host’s liver before infecting and destroying red blood cells.
Early diagnosis can in some places help to treat and manage malaria. Some nations, however, still lack the tools to conduct successful screening.
There is actually no vaccine approved for use in the U.S., even though one vaccine has a European licence.
Advances in diagnosis in the early 1950’s removed malaria from the Population. But there are still between 1,500 and 2,000 cases per year, mainly of people who have recently traveled to malaria-endemic areas.
Symptoms
Doctors divide malaria symptoms into two categories: Uncomplicated and severe malaria.
Uncomplicated malaria
If signs are present a doctor may issue this diagnosis, but there are no signs that indicate serious infection or dysfunction of vital organs.
Without treatment this type can turn into severe malaria, or if the host has low immunity or no.
Usually, symptoms of uncomplicated malaria last 6 to 10 hours, and recur every second day.
Many parasite strains may have a longer duration, or cause mixed symptoms.
Since the symptoms resemble those of flu, in areas where malaria is less common, they may remain undiagnosed or misdiagnosed.
Symptoms progress as follows in uncomplicated malaria, through stages of cold, humid, and sweating:
- 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
Many people identify the symptoms as malaria in places where malaria is common, and treat themselves without a doctor visiting.
Severe malaria
Medical or laboratory research in severe malaria shows symptoms 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
Treatment is intended to kill the bloodstream Plasmodium parasite.
In order to minimize the risk of disease transmission in the surrounding population, those without symptoms can be treated for infection.
The World Health Organization (WHO) is recommending artemisinin-based combination therapy (ACT) to treat uncomplicated malaria.
Artemisinin comes from the herb Artemisia annua, which is best known as sweet wormwood. It rapidly decreases blood stream concentration of Plasmodium parasites.
Often the practitioners combine ACT with a partner drug. ACT aims at raising the number of parasites within the first 3 days of infection, while the partner drugs remove the remaining.
Expanding access to ACT care around the world has helped reduce malaria’s effects, but the disease is becoming increasingly resistant to ACT’s effect.
In areas where malaria is resistant to ACT there must be an appropriate partner drug in the treatment.
The WHO has warned that there will possibly be no alternatives to artemisinin available for many years.
Prevention
There are several ways to keep malaria at bay.
Vaccination
Work to develop safe and effective global malaria vaccines is ongoing, with one vaccine having already been approved in Europe. No vaccine is approved in the United States yet.
Look for medical attention as early as possible for suspected malaria symptoms.
Advice for travelers
Although malaria isn’t endemic to the U.S., traveling around the world to many countries implies a risk.
The Centers for Disease Control are recommending that travelers 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, including insect repellants, insecticides, pre-treated bed nets, and appropriate clothing
- be aware of the symptoms of malaria
In emergency situations, local health authorities may conduct “fogging” in some countries, or spraying areas with pesticides similar to those used in household sprays.
The WHO points out that these are not dangerous to humans, as pesticide concentrations are only high enough to kill mosquitoes.
While abroad, travelers should avoid situations where possible which may increase the risk of mosquito biting. Precautions involve having an air-conditioned room, avoiding camping by stagnant water and wearing clothing that covers the body when mosquitoes are most likely to be around.
The traveler may be susceptible to malaria symptoms for a year after returning home. It might not be possible to donate blood for some time, either.
Causes
Malaria occurs when Plasmodium infects the body through a bite from the female Anopheles mosquito. Malaria can only be spread by the Anopheles mosquito.
Effective production of the mosquito parasite is based on a variety of factors, the most important being humidity and ambient temperature.
When a human host is bitten by an infected mosquito the virus enters the bloodstream and lies dormant within the liver.
For an average of 10.5 days, the host does not have any symptoms but the malaria parasite does begin to multiply during this period.
The liver then releases these new malaria parasites back into the bloodstream where red blood cells are infected and spread further. Some parasites of malaria linger in the liver and do not spread til later, leading to recurrence.
An unaffected mosquito acquires parasites once they feed on a parson with malaria. This starts the cycle once again.
Diagnosis
Early diagnosis is critical for recovery from malaria.
Anyone showing signs of malaria should seek testing and treatment immediately.
Based on the facilities available, the WHO strongly advise confirmation of the parasite by microscopic laboratory testing or a rapid diagnostic test (RDT).
No combination of symptoms can accurately differentiate malaria from other causes, so it is important to provide a parasitological test to diagnose and treat the disease.
In some malaria-endemic areas, such as sub-Saharan Africa, the severity of the disease may induce mild immunity in a significant proportion of the local population.
Many people bear the parasites in their bloodstream, but do not get sick.
