Hospital: Report by IDSS, facsimile, mail or phone
Lab: Report by IDSS, facsimile, mail or phone
Physician: Report by facsimile, mail or phone
Local Public Health Agency (LPHA): Report by IDSS, facsimile, mail or phone. Follow-up required.
Iowa Department of Public Health
Disease Reporting Hotline: (800) 362-2736
Secure Fax: (515) 281-5698
There are four Plasmodium species (sporozoan parasites) that cause malaria in humans. They are Plasmodium vivax, P. malariae, P. ovale and P. falciparum.
B. Clinical Description
Symptoms: The classic symptoms of malaria are high fever with chills, sweats, and headache, which may be paroxysmal (occurring at intervals or with remissions and intensification of symptoms). The fever and paroxysmal symptoms generally occur in cycles of 1 - 3 days depending on the species causing the infection. Other symptoms can include malaise, nausea, vomiting, diarrhea, cough, arthralgia (joint aches), respiratory distress and abdominal and back pain. Paleness and jaundice may also be present. Enlargement of the liver and spleen (hepatosplenomegaly) may occur and is more prominent in chronic infections. Infection with P. falciparum is potentially acutely fatal and most commonly manifests as a febrile illness with or without coagulation defects, shock, renal and liver failure, acute encephalopathy, pulmonary and cerebral edema, and coma. The case-fatality rate for falciparum malaria is 10-40% in the absence of prompt treatment.
Duration of an untreated primary attack can vary from a week to a month or longer. Relapses of P. vivax and P. ovale infections can occur at irregular intervals. Malaria infections may persist for life (chronic infections), with or without recurrent episodes of fever.
Humans are the only important reservoir for human malaria. Non-human primates are naturally infected by many malarial species that can potentially infect humans, but natural transmission from non-human primates to humans is extremely rare.
D. Modes of Transmission
- Malaria is transmitted by the bite of an infected female Anopheles mosquito.
- Rarely congenital (from mother to fetus) transmission may occur as well as transmission through transfusions or the use of contaminated needles.
E. Incubation Period
- The time between the infective bite and the appearance of clinical symptoms is approximately 7-14 (9-14) days for P. falciparum, 8-14 (12-18) days for P. vivax and P. ovale, and 7-30 (18-40) days for P. malariae.
- With some strains of P. vivax, mostly from temperate areas, there may be a prolonged incubation period of 8 - 10 (6-12) months; even longer incubations may occur with P. ovale.
- With infections acquired by blood transfusion, the incubation period is dependant on the number of parasites infused; it is usually short, but may range up to 2 months.
F. Period of Communicability or Infectious Period
Malaria is not directly communicable from person-to-person except for congenital transmission; however, during parasitemia, the disease may be transmitted to other persons through blood transfusion or through shared contaminated needles. Infected human hosts remain infectious for Anopheles mosquitoes for prolonged periods of time (1 - 3 years, or longer, depending on the species) if they are not adequately treated.
Malaria is endemic throughout the tropical areas of the world. About half of the world’s population lives in areas where transmission occurs frequently. In 2010 an estimated 219 million cases of malaria occurred worldwide and 660,000 people died, with most (91%) in the African Region. Areas with the highest prevalence include sub-Saharan Africa, parts of Central and South America, India, and parts of Oceania and Southeast Asia. Transmission is also possible in more temperate climates such as in the United States, where Anopheles mosquitoes are present. Mosquitoes in airplanes flying from tropical climates have been the source of occasional cases in persons working or living near international airports (“airport malaria”) and further transmission of imported cases by local mosquitoes has been documented. However, nearly all of the malaria cases reported annually in the United States (approximately 1500) are acquired abroad. P. vivax and P. falciparum are the most common species worldwide. The worldwide spread of strains of chloroquine-resistant P. falciparum and P. vivax is of increasing importance. Resistance to other antimalarial drugs is now occurring in many areas where the drugs are widely used. The only cases occurring in Iowa are imported.
H. Bioterrorism Potential
I. Additional Information
The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions for Malaria can be found at: www.cdc.gov/osels/ph_surveillance/nndss/phs/infdis.htm#top
CSTE case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)
American Academy of Pediatrics. 2003 Red Book: Report of the Committee on Infectious Diseases, 26th Edition. Illinois, American Academy of Pediatrics, 2003.
CDC. Regional Malaria Information. Available at www.cdc.gov/travel/regionalmalaria
Heymann, D.L., ed. Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.
MDPH. Regulation 105 CMR 300.000: Reportable Diseases and Isolation and Quarantine Requirements. MDPH, Promulgated November 1998, (Printed July 1999).