Malaria

Malaria is a significant and deadly global health problem affecting approximately 218 million people and causing over 600,000 deaths annually (Menkin-Smith & Winders, 2022; Florida Health, 2023; World Health Organization [WHO], 2023). Malaria, considered a medical emergency, is found in tropical areas and is preventable and curable. It is caused by one of four parasites: Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, and Plasmodium ovale, and is transmitted via "the bite of a female Anopheles species mosquito, with transmission occurring mainly between dusk and dawn (Centers for Disease Control and Prevention [CDC], 2023; Florida Health, 2023). Other mechanisms for transmission include congenitally acquired disease, blood transfusion, sharing contaminated needles, organ transplants, and nosocomial transmission (Breman, 2023). Although the risk of locally acquired malaria is low in the United States, with approximately 1,700 cases annually, malaria has recently been found in Florida and Texas (CDC, 2023). Anyone can develop malaria if exposed.

Malaria is a nationally notifiable disease. Areas where malaria is found are greatly influenced by temperature, humidity, and rainfall. The areas of highest transmission occur in Africa South of the Sahara and parts of Oceania, such as Papua New Guinea (CDC, 2023; WHO, 2023). Travel to other countries is commonly seen in most malaria cases in the United States, but there are regions where mosquito-transmitted malaria cases occur (e.g., Florida and Texas).

People can develop malaria after being bitten by an infective female Anopheles mosquito. They are the only type of mosquito that can transmit malaria. When a mosquito bites an infected person, a small amount of blood is taken, which contains a malaria parasite. The parasite mixes with the mosquito's saliva and is transmitted to the next person who is bitten (CDC, 2023). The malaria parasite is found in infected people's red blood cells, allowing for additional transmission of malaria through blood transfusions, organ transplants, or shared needles contaminated with infected blood. Malaria can also be transmitted from mother to infant during delivery (CDC, 2023). However, malaria cannot be sexually transmitted and is not airborne.

Anopheles Mosquito

The principal determinants of malaria include the number or density of mosquitos, the habitats, such as indoors or outdoors, and the longevity of the female vectors. The transmission of malaria is directly proportional to the vector's density or number, the square of the number of human bites daily per mosquito, and the 10th power of the probability of the mosquito's daily survival (Breman, 2023). Mosquito longevity is vital to transmission risk because of the parasite's life cycle, which lasts for eight to 30 days, depending on the species of Plasmodium and ambient temperature; therefore, to transmit malaria, the mosquito must survive for more than ten days. The most effective malaria vectors are those such as Anopheles gambiae, often found in tropical climates such as Africa, and are long-lived, breed readily, rest and bite within dwellings and environments, and bite humans in preference to other animals (Breman, 2023).

Infected Red Blood Cell

There are methods that exist to prevent the transmission and development of malaria.

Vector control. Vector control, utilizing insecticide-treated nets (ITNs) and indoor residual spraying (IRS), is effective at reducing mosquito longevity (WHO, 2023). Controlling the vector density or number of mosquitos is vital to preventing malaria. Mosquitos breed by laying eggs in and near standing water. To disrupt the mosquito life cycle, drain any standing water from bird baths, pets' water bowls, garbage cans, house gutters, pool covers, flowerpots, old tires, and any other containers at least weekly. As little as one teaspoon or bottle cap of water standing for more than one week is enough for mosquitos to breed in and multiply (Florida Health, 2023). Mosquitos can live indoors and will bite at any time. Keep mosquitos out of the home by repairing broken screens on windows, doors, or porches.

Bite protection. The first line of defense is to avoid contact with mosquitos by remaining indoors in a screened or air-conditioned area during the peak biting periods of dusk and dawn. Vectors tend to feed in the early mornings rather than late at night (Breman, 2023). Cover the body by wearing long-sleeved shirts, long pants, and hats. Protect infants by draping their carrier with mosquito netting with an elastic edge that remains tight around the carrier (Florida Health, 2023; WHO, 2023).

When outside, it is important to use Environmental Protection Agency (EPA) registered insect repellent containing one of the following active ingredients: N.N-diethyl-meta-toluamide or DEET (Off!® Cutter®, Sawyer®, Ultrathon®), Picaridin or KBR 3023, Bayrepel and icaridin (Skin So Soft Bug Guard Plus®), oil of lemon eucalyptus (OLE), para-menthane-3,8-dio or PMD (Repel®) or IR3535 (Skin So Soft Bug Guard Plus Expedition®, Skin Smart®). DEET has been used for over 70 years and is considered the gold standard of insect repellents. No other compound covers as broad a spectrum of arthropods or offers the extended duration of action" (Breisch, 2020). Repellents containing higher concentrations may have a longer effect, but concentrations over 50% provide no greater protection, and time-released products are preferred over liquid sprays. Any product containing 10 to 35 percent of the active ingredient is adequate in most circumstances. Higher concentrations should be used if time outdoors exceeds three to four hours. Do not use insect repellent on children younger than two months or open areas of skin such as cuts or wounds. Frequent reapplication is not required. If both sunscreen and repellent are required, sunscreen should be applied first. Serious adverse reactions to repellents are uncommon, but they can cause dermatitis, allergic reactions, and, rarely, neurotoxicity. DEET is not carcinogenic (Breisch, 2020; WHO, 2023).

Preventive medication. Medications available in the United States to prevent and treat malaria include Chloroquine, quinine sulfate, hydroxychloroquine, mefloquine, atovaquone, and proguanil. To prevent malaria, drugs like mefloquine hydrochloride must be started at least two weeks before exposure to malaria and continue for four weeks after exposure, so it is important to consider the travel location and plan accordingly to prevent infection risk. "A review of antimalarial drug quality in Asia and Africa showed an alarming prevalence of counterfeit drugs on the shelves of pharmacies in multiple countries; up to 36 percent of antimalarial drugs and 43 percent of the artemisinin combination drugs were falsified" (Breman, 2023, pp 19). Regulations from the Federal Drug Administration (FDA) minimize the risk of counterfeit drugs sold in the United States.

Malaria is a medical emergency, and patients suspected of this illness should receive rapid diagnosis and treatment within 24 hours of presentation. Clinical manifestations of malaria are non-specific and can be confused with other common illnesses. Symptoms include fever, chills, headache, myalgias, and fatigue. Nausea, vomiting, and diarrhea may or may not be presenting symptoms. Malaria may cause anemia and jaundice because of the loss of red blood cells. If not identified and appropriately treated, malaria can progress to a change in mental status, seizures, renal failure, coma, and death.

Any patient who presents with a fever of unknown origin and who lives in an area with recent, locally acquired malaria should be considered a candidate for the diagnosis. Symptoms typically begin ten days to four weeks after infection. Pregnant women with malaria are at high risk of maternal and perinatal morbidity and mortality. Some variants of malaria remain dormant in the liver and require additional treatment. Failure to identify and treat dormant malaria can result in lifelong chronic, relapsing infections. Diagnosis is made by examination of a blood sample under the microscope for the presence of malaria parasites (CDC, 2023).

Laboratory findings with malaria include thrombocytopenia (60% of cases), hyperbilirubinemia (40% of cases), anemia (30% of cases), and elevated hepatic aminotransferase levels (25% of cases). The degree of the laboratory abnormalities indicates the severity of the diagnosis.

The most common clinical presentation and cause of death in adults with severe malaria is cerebral malaria. It may have a dramatic and sudden onset with seizures or gradual drowsiness and confusion, with the patient slipping into a coma. Acute respiratory injury may also have a sudden onset, with the patient experiencing pulmonary edema, tachypnea, and dyspnea (Trampuz et al., 2003).

Treatment is guided by four main factors: species of infecting Plasmodium, clinical presentation of the patient, drug susceptibility of infecting parasite, and previous use of antimalarial drugs, including any medications taken for malaria chemoprophylaxis.

Plasmodium falciparum and Plasmodium knowlesi infections are more serious variants causing rapid progression and death. Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae cause less severe disease. However, Plasmodium vivax and Plasmodium ovale can remain dormant in the liver and cause relapsing illness.

According to the CDC (2023), patients are categorized as either having uncomplicated or severe malaria. Uncomplicated malaria can be treated with oral antimalarials. Patients experiencing a mental status change or coma, severe anemia (hemoglobin less than seven g/dL), acute kidney injury, shock, disseminated intravascular coagulation, acidosis, jaundice, or parasitemia of more than five percent are considered to have severe malaria and are treated more aggressively with intravenous antimalarial drugs. If a patient were taking antimalarial drugs for malaria chemoprophylaxis at the time of infection, this drug would not be used for treatment as it was ineffective in prevention.

Once treatment starts, blood smears are repeated every 12-24 hours to monitor drug effectiveness and a decrease in parasite density. The CDC (2023) does recommend a documented negative malarial smear after treatment, but this can be done in an outpatient setting, depending on clinical judgment.

Thomas is traveling to Venice, Florida (Sarasota County) with his friends on spring break. They plan to stay in a local hotel near Venice Beach and snorkel on the coral reef there. Thomas sees his primary care physician before his trip for a sore throat. His doctor diagnoses Thomas with a viral throat infection but recommends that Thomas take an antimalarial drug. Thomas was unaware that malaria was found in the United States and was suddenly very concerned about going on his trip.

Thomas learns that malaria is preventable and treatable. He begins the antimalarial medication his doctor prescribed two weeks before his trip and plans to take clothing to cover his exposed skin at peek-biting times. He also plans to pack bug spray and sunscreen to prevent being bitten. Although he is still concerned about acquiring malaria, Thomas knows that being smart about his behaviors will reduce his risk and allow him to enjoy his spring break.

People develop malaria by being bitten by an infective female Anopheles mosquito. Only Anopheles mosquitoes can transmit malaria. The malaria parasite is found in the red blood cells of infected people and can be prevented through diligent vector control, bite protection, and preventive medications. Malaria can be deadly, so prompt identification and treatment are vital to positive outcomes without long-term complications.

• Breisch, N. L. (2020). Prevention of arthropod and insect bites: Repellents and other measures. UpToDate. Visit Source.
• Breman, J. G. (2023). Malaria: Epidemiology, prevention, and control. UpToDate. Visit Source.
• Centers for Disease Control and Prevention (CDC). (2023). Malaria Treatment (United States). Centers for Disease Control and Prevention. Visit Source.
• Florida Health. (2023). Malaria. Visit Source.
• Menkin-Smith, L., & Winders, W. T. (2022). Plasmodium vivax malaria. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Visit Source.
• Trampuz, A., Jereb, M., Muzlovic, I., & Prabhu, R. M. (2003). Clinical review: Severe malaria. Critical care (London, England), 7(4), 315–323. Visit Source.
• World Health Organization (WHO). (2023). WHO Guidelines for malaria. World Health Organization. Visit Source.