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Malaria: Additional Information

Background

Four parasitic protozoa of the genus Plasmodium (P. ovale, P. vivax, P. malariae and P. falciparum) cause human malaria. Of the four species, P. falciparum causes the most severe morbidity and mortality due to incidence of cerebral malaria.

All 4 species are transmitted through the bite of an infected female Anopheles mosquito.

At risk for contraction of malaria are non-immune persons living in or traveling to endemic areas. This will normally include most tourists and expatriates travelling and living in Indonesia.

The vector, the Anopheles mosquito, passes the malaria parasite, which is contained in its saliva, into its host while obtaining a blood meal. Plasmodia enter circulating red blood cells and feed on the hemoglobin and other proteins within the cells. One brood of parasites becomes dominant and is responsible for the synchronous nature of the clinical symptoms of malaria.

Flu-like symptoms are experienced by the host. These symptoms include chills, headache, myalgias, and malaise, and they occur in a cyclic pattern. The parasite may also cause jaundice and anaemia. P. falciparum, the most malignant of the 4 species of Plasmodium, may induce kidney failure, coma, and death. Malaria-induced death is preventable if the proper treatment is sought and implemented.

P. vivax and P. ovale may produce a dormant form that persists in the liver of infected individuals and emerges at a later time. Therefore, these species require treatment to kill any dormant protozoan, as well as the actively infecting organisms.

Frequency

  • In Indonesia: Malaria is endemic to most areas of Indonesia, outside of the metropolitan areas. There are now some reported cases of malaria in tourist areas that were previously free from the disease. Recently there have been a number of severe cases of malaria in the expatriate population, in addition, there have been at least four deaths in the last year. In addition, there is an increasing amount of drug resistance (particularly to chloroquine) in P. Falciparum. Unfortunately, chloroquine is still being widely used for prophylaxis and standard treatment of malaria in Indonesia.
  • Internationally: Malaria is still an enormous medical issue with 300-500 million cases annually reported. It is most prevalent in rural tropical areas below elevations of 1000 metres, but is not limited to these climates. P. falciparum is found mostly in the tropics and, along with P. vivax, makes up 95% of malarial infections diagnosed worldwide. P. vivax is more widely distributed than P. falciparum, but it causes less morbidity and mortality. Both of these forms are found in South East Asia.

Mortality/Morbidity

  • Internationally, there are 1.5-3.5 million deaths annually. Of these deaths, the overwhelming majority is among children aged 5 years or younger.
  • These deaths are unnecessary since malaria is preventable and treatable. However, lack of prevention and treatment due to poverty, war, and other economic and social instabilities in endemic areas results in continuing infection and death each year.

Age

All ages are vulnerable. Mortality is highest in children younger than 5 years.

History

Most cases live in, or have recently traveled to, an endemic area. However, a few cases are reported each year with no history of such travel.
  • Determine the patient's immune status, age, allergies, other medical conditions, other medications, and pregnancy status.
  • The patient usually remains asymptomatic for a week or more after the infecting mosquito bite.
  • Typical symptoms include:
    • Coughing
    • Fatigue
    • Malaise
    • Shaking chills
    • Arthralgia (painful joints)
    • Myalgia (muscular aches and pains)
    • Paroxysms (a period of shivering and chills lasting for 1-2 hours, followed by a high fever)
  • Less common symptoms include:
    • Anorexia and lethargy
    • Nausea and vomiting
    • Diarrhea
    • Headache

Physical

  • Physical symptoms that may be noted with malaria include the following:
    • Tachycardia
    • Fever
    • Hypotension
    • Signs of anemia
    • Splenomegaly

Causes

Malaria is most often caused by the bite of a female Anopheles mosquito that is infected with one of the four species of the protozoan genus Plasmodium.

P. falciparum is the most malignant form of malaria, as its infection is not limited to the red clood cells of a particular age and, therefore represents the highest level of parasitemia (parasites in the blood stream) among the four Plasmodium species. This species also causes vascular obstruction due to its ability to adhere to the cell walls of blood vessels, a property that leads to most of the complications of a P. falciparum infection.

P. falciparum can cause cerebral malaria, pulmonary edema (fluid in the lungs), the rapid development of anemia, and renal problems. Other less common routes of infection are through blood transfusion and maternal-fetal transmission.

Deterrence/Prevention

  • Avoid endemic regions.
  • Take the proper prophylactic drugs at proper intervals if traveling to endemic regions.
  • Use topical insect repellent (30-35% DEET), especially from dusk to dawn.
  • Wear long-sleeved, permethrin-coated clothing if not permethrin-allergic and spray repellent under beds, chairs, tables, and along walls.
  • Sleep under fine-nylon netting impregnated with permethrin.
  • Avoid wearing perfumes and colognes.
  • Seek out medical attention immediately upon contracting any tropical fever or flu-like illness.

Complications

Complications caused by P. falciparum include the following:
  • Coma (cerebral malaria)
    • Defined as coma, altered mental status, or multiple seizures with P. falciparum in the blood. This complication is the most common cause of death in malaria patients. If untreated, cerebral malaria is lethal. Even with treatment, 15% of children and 20% of adults who develop cerebral malaria die. The symptoms of cerebral malaria are similar to those of toxic encephalopathy.
  • Seizures
  • Renal failure
    • Up to 30% of nonimmune adults infected with P falciparum suffer acute renal failure.
  • Haemoglobinuria (blackwater fever)
    • Blackwater fever is the passage of dark, Madeira-colored urine. This is due to haemolysis (destruction) of the blood cells
  • Profound hypoglycemia (low blood sugar)
    • Hypoglycemia often occurs in young children and pregnant women and is difficult to diagnose
  • Lactic acidosis
    • This occurs when small blood vessels become clogged with P. falciparum.
  • Haemolysis resulting in severe anemia and jaundice
  • Bleeding (coagulopathy)

Prognosis (outcome)

Most uncomplicated cases of malaria show marked improvement within 48 hours after the initiation of treatment and are fever-free after 96 hours.

Only P. falciparum infection carries a poor prognosis with a high mortality rate if untreated. However, if diagnosed early and treated appropriately, the prognosis is often excellent.

Special Concerns

  • Pediatrics
    • In children, malaria has a shorter course, often rapidly progressing to severe malaria.
    • Children are more likely to present with hypoglycemia (low blood sugar), seizures, severe anemia, and sudden death; but, they are much less likely to develop renal failure, pulmonary edema (fluid in the lungs), or jaundice.
  • Cerebral malaria leaves between 9-26% of children with neurologic sequelae (mental complications due to malarial infection), but about half of all cases can be completely resolved with time.
  • Most antimalarial drugs are very effective and safe in children, provided that the proper dosage is administered. It is common for children to recover from malaria much faster than adults do.

If you have medical-related questions about living in Indonesia to ask of medical professionals, see Ask the Experts.

We trust this information will assist you in making correct choices regarding your health and welfare. However, it is not intended to be a substitute for personalized advice from your medical adviser.

Our appreciation to Dr. Paul Vandewalle of International SOS, an AEA Company who has contributed this article in response to a growing health threat faced by expatriates in Indonesia.