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Reporting | Epidemiology | Evaluation
and Diagnosis | References
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Reporting
We encourage clinicians to report all cases of laboratory-confirmed malaria
to help CDC's surveillance efforts. Refer to our information on the Malaria
Case Surveillance Report Form.
To report an adverse event to an antimalarial drug
If your patient has experienced an adverse event while taking an antimalarial drug, you can report that side effect to MedWatch, the FDA Safety Information and Adverse Event Reporting Program. Reporting an event is voluntary. However, your participation is encouraged in order to keep safe and effective drugs and devices available on the market.
To submit your voluntary report, do one of the following:
- Complete the voluntary form 3500 online at www.accessdata.fda.gov/scripts/medwatch/ *
- Call 1-800-FDA-1088 to report by telephone
- Download a copy of the form and either fax it to 1-800-FDA-0178 or mail it using the postage-paid addressed form.
For more information visit www.fda.gov/medwatch/report/hcp.htm *
Epidemiology
Malaria continues to be one of the most important and devastating infectious
diseases in developing areas of the world. Worldwide, over 40% of the population
lives in areas where malaria transmission occurs (i.e., parts of Africa, Asia,
the Middle East, Central and South America, Hispaniola, and Oceania).1 It
is estimated that 300-500 million cases of malaria occur each year resulting
in 750,000-2 million deaths.2
While malaria transmission was successfully interrupted in the United
States during the late 1940s, malaria remains a constant health threat
for U.S. travelers to malarious areas and immigrants arriving from
malarious areas. With approximately 27 million U.S. residents traveling
each year to malarious areas, it is important for clinicians to provide
pre-travel advice on malaria prevention, to remain alert to the possibility
of malaria in persons returning from these areas, and to treat malaria
cases promptly and effectively. While the vast majority of malaria
cases diagnosed in the U.S. are imported (i.e., acquired outside of
the United States and its territories), congenital infections, infections
through exposure to infected blood or blood products, and infections
through local mosquito-borne transmission still occur.3-6
In 2004, 1,324 cases of malaria were reported in the United States.3 Plasmodium falciparum, the most severe and life-threatening
form of the disease was identified in 50% of the cases. Malaria
cases were reported from all 50 states with New York City (214), California
(130), and New Jersey (75) reporting the highest number. Of the 1,324
malaria cases, 775 occurred in U.S. civilians, all of which
were imported.3 Of the civilian patients with imported
malaria, 65% did not take any chemoprophylaxis and only 20% were compliant
with a chemoprophylactic regimen recommended by the Centers for Disease
Control and Prevention (CDC) for the area in which they traveled.
Eighty-eight percent of patients with imported malaria reported
symptom onset after arriving back in the United States and, for patients
with P. falciparum infections, 81% experienced symptom onset
within one month after arrival back in the United States. Four patients died. Risk factors for fatal malaria include failure to take recommended
chemoprophylaxis, refusal of or delay in seeking medical care, and
misdiagnosis.7
Evaluation and Diagnosis
Because malaria cases are seen relatively rarely in North America,
misdiagnosis by clinicians and laboratorians has been a commonly documented
problem in case series.8-12 However, malaria is a common
illness in areas where it is transmitted, and therefore the diagnosis
of malaria should routinely be considered for anyone who has traveled
to an area with known malaria transmission in the past several months
preceding symptom onset. Symptoms of malaria are generally non-specific
and most commonly consist of fever, malaise, weakness, gastrointestinal
complaints (nausea, vomiting, diarrhea), neurologic complaints (dizziness,
confusion, disorientation, coma), headache, back pain, myalgia, chills,
and/or cough.7, 13 The diagnosis of malaria should also be
considered in any person with fever of unknown origin regardless of
travel history. Patients suspected of having malaria infection should
be urgently evaluated. Treatment for malaria should not be initiated until the diagnosis has been confirmed by laboratory investigations. "Presumptive treatment" without the benefit of laboratory confirmation should be reserved for extreme circumstances (strong clinical suspicion, severe disease, impossibility of obtaining prompt laboratory confirmation).
Laboratory diagnosis of malaria can be made through microscopic examination
of thick and thin blood smears.3 Thick blood smears are more
sensitive in detecting malaria parasites because the blood is more concentrated
allowing for a greater volume of blood to be examined; however, thick smears
are more difficult to read. Laboratories that have limited experience may
prefer to use thin smears, which can aid in parasitic species identification.
Blood films need to be read immediately; off-hours, qualified personnel
who can perform this function should be on-call. A negative blood smear
makes the diagnosis of malaria unlikely. However, because non-immune
individuals may be symptomatic at very low parasite densities that initially
may be undetectable by blood smear, blood smears should be repeated every
12-24 hours for a total of 48-72 hours.
After the presence of malaria parasites on a blood smear is detected, the
parasite density should then be estimated. The parasite density can
be estimated by looking at a monolayer of red blood cells (RBCs) on the
thin smear using the oil immersion objective at 100x. The slide should
be examined where the RBCs are more or less touching (approximately 400
RBCs per field). The parasite density can then be estimated from the percentage
of infected RBCs.14
In addition to microscopy, other laboratory diagnostic tests are available.
Several antigen detection tests using a “dipstick” format exist
but are not yet approved for general diagnostic use in the United States.
Parasite nucleic acid detection using polymerase chain reaction (PCR)
are more sensitive and specific than microscopy but can be performed
only in reference laboratories and should be reserved for specific
instances (e.g., back up or confirmation of microscopy). Serologic
tests, also performed in reference laboratories, can be used to assess
past malaria experience but not current infection by malaria parasites.
Your state health department or the CDC can be contacted for more information
on utilizing one of these tests.
References
- World malaria situation in 1994. Part I. Population
at risk. Wkly Epidemiol Rec, 1997. 72(36):
p. 269-74.
- Breman, J.G., The ears of the hippopotamus: manifestations,
determinants, and estimates of the malaria burden. Am
J Trop Med Hyg, 2001. 64(1-2 Suppl): p.
1-11.
- CDC, Malaria surveillance – United States, 2004. MMWR Surveill Summ, 2006. 66(No. SS-04): p. 23-37.
- CDC, Congenital malaria as a result of Plasmodium malariae--North
Carolina, 2000. MMWR Morb Mortal Wkly Rep, 2002. 51(8):
p. 164-5.
- CDC, Probable transfusion-transmitted malaria--Houston,
Texas, 2003. MMWR Morb Mortal Wkly Rep, 2003. 52(44):
p. 1075-6.
- CDC, Local transmission of Plasmodium vivax malaria--Palm
Beach County, Florida, 2003. MMWR Morb Mortal Wkly Rep,
2003. 52(38): p. 908-11.
- Greenberg, A.E. and H.O. Lobel, Mortality from Plasmodium
falciparum malaria in travelers from the United States, 1959
to 1987. Ann Intern Med, 1990. 113(4):
p. 326-7.
- Moore, T.A., et al., Imported malaria in the 1990s.
A report of 59 cases from Houston, Tex. Arch Fam Med,
1994. 3(2): p. 130-6.
- Kain, K.C., et al., Imported malaria: prospective analysis
of problems in diagnosis and management. Clin Infect
Dis, 1998. 27(1): p. 142-9.
- Kain, K.C., et al., Malaria deaths in visitors to
Canada and in Canadian travellers: a case series. Cmaj,
2001. 164(5): p. 654-9.
- Svenson, J.E., et al., Imported malaria. Clinical
presentation and examination of symptomatic travelers. Arch
Intern Med, 1995. 155(8): p. 861-8.
- Kyriacou, D.N., et al., Emergency department presentation
and misdiagnosis of imported falciparum malaria. Ann
Emerg Med, 1996. 27(6): p. 696-9.
- White, N.J., The treatment of malaria. N Engl
J Med, 1996. 335(11): p. 800-6.
- Zucker, J.R. and C.C. Campbell, Malaria. Principles
of prevention and treatment. Infect Dis Clin North Am,
1993. 7(3): p. 547-67.
- Severe falciparum malaria. World Health Organization,
Communicable Diseases Cluster. Trans R Soc Trop Med
Hyg, 2000. 94 Suppl 1: p. S1-90.
- CDC, Availability and use of parenteral quinidine
gluconate for severe or complicated malaria. MMWR Morb
Mortal Wkly Rep, 2000. 49(50): p. 1138-40.
- Miller, K.D., A.E. Greenberg, and C.C. Campbell, Treatment
of severe malaria in the United States with a continuous
infusion of quinidine gluconate and exchange transfusion. N
Engl J Med, 1989. 321(2): p. 65-70.
- Powell, V.I. and K. Grima, Exchange transfusion for
malaria and Babesia infection. Transfus Med Rev, 2002. 16(3):
p. 239-50.
- Luxemburger, C., et al., The epidemiology of severe
malaria in an area of low transmission in Thailand. Trans
R Soc Trop Med Hyg, 1997. 91(3): p. 256-62.
- Nosten, F., et al., The effects of mefloquine treatment
in pregnancy. Clin Infect Dis, 1999. 28(4):
p. 808-15.
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Page last modified : June 13, 2006
Content source: Division of Parasitic Diseases
National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)
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