US Laboratories Surveyed for Malaria Diagnosis

The accuracy of laboratories in detecting and identifying malaria parasites and assessing malaria screening practices has been evaluated.

The American Proficiency Institute (API; Traverse City, MI, USA) has examined the diagnostic precision of laboratories in the US to identify different species of malaria parasites and assessed whether the correct follow-up procedures were practiced.

Malaria is usually diagnosed in the laboratory by microscopic examination of a stained thick and thin blood smear or by the use of a rapid diagnostic test (RDT). Malaria RDTs detect specific antigens (proteins) produced by malaria parasites, that are present in the blood of infected or recently infected individuals. Some RDTs can detect only one species of the malaria parasite, Plasmodium falciparum, while some also detect other species of the parasite, P. vivax, P. malariae and P. ovale. Blood for these tests are commonly obtained from a finger-prick.

API reviewed proficiency-testing data from 1999 to 2008 to determine the rates of unacceptable responses for detecting and identifying Plasmodium species, the parasites that cause malaria. Laboratories in the United States were better able to detect and identify P. falciparum than other types of parasite species. However, when assessing malaria screening practices among current proficiency testing providers, the review found that half of the surveyed laboratories failed to offer a complete diagnostic workup, 25.0% failed to screen both thick and thin slides, and 36.1% failed to issue a final report within 24 hours.

The US Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA) estimates that approximately 1,500 cases of imported malaria are diagnosed each year in the US. Of these, 71% were acquired in Africa and about 41% were due to P. falciparum. In December 2010, an autochthonous case of P. falciparum malaria was diagnosed in a 31-year-old female resident of Jacksonville (FL, USA) who had no history of international travel.

Daniel C. Edson, M.S., M.T. (ASCP), API president and lead author of the report, said, "Malaria is a serious, sometimes fatal, disease and laboratories should be better prepared to identify various species of malaria parasites, the more rapidly patients may be treated and hopefully cured". The study was published in December 2010, in Lab Medicine.

Related Links:
American Proficiency Institute
CDC