Malaria (Plasmodium species)

Test codes:

X0014 - Ultrasensitive qualitative screen for Plasmodium species by real time PCR. This assay detects but does not differentiate most malaria-causing Plasmodium species, including P. falciparum, P. malariae, P. vivax, P. ovale, P. knowlesi, P. fieldi, P. hylobati, P. juxtanucleare, P. yoelii, P. brasilianum, P. cynomolgi, P. inui, P. schwetzi, P. reichenowi, P. eyles, P.jefferyi, P. youngi, P. pitheci, P. silvaticum, P. coatneyi, P. fragile, P. simiovale, P. gonderi, P. simium, P. cathemerium, P. gallinaceum and P. relictum.

X0012 - Ultrasensitive qualitative detection of Plasmodium inui by real time PCR. This assay does not detect other Plasmodium species.

Malaria is caused by protozoan parasites of the genus Plasmodium. The parasites are transmitted by infected mosquitos. As the infected female mosquito takes a blood meal, it injects the parasite, which travels in the bloodstream to the liver. Inside the liver, the organism undergoes several developmental changes leading to the release of a large number of merozoites. These merozoites invade the red blood cells. The asexual stages often seen in blood films are young trophozoites (also known as “ring forms”), mature trophozoites, and the dividing schizonts that yield the merozoites for a new generation. The liver then acts as a reservoir from which periodic bouts of parasitemia may emanate.

Parasitemia in infected animals can fluctuate dramatically over short periods, so Plasmodium screening should be performed at multiple time points. In particular, stress or other immune-suppressive events may trigger an increase in parasitemia from previously undetectable levels. Therefore it is ideal when feasible to screen using liver or spleen biopsy, because the titer of Plasmodium organisms is more consistently detectable in these tissues than in peripheral blood.

Traditionally, malaria screening and diagnosis relied on microscopic examination of blood smears. This method is fast and cheap but has a very low sensitivity. Successful detection in blood smears also depends on collecting the specimen at the peak of the parasitemia. Antibody detection can be used to diagnose the disease but paired serum samples several weeks apart are required in order to identify actively infected animals, making rapid diagnosis impossible. Furthermore, most serology testing currently available targets the Plasmodium species that infect humans, such as P. malariae, P. falciparum, P. vivax and P. ovale. Reagents used for these human serology tests are not useful for screening for malaria in animals. Molecular detection by PCR is a rapid, specific and sensitive method for accurately diagnosing and identifying carriers.

Utilities:

• Help confirm the disease causing agent
• Help ensure that animal colonies are free of malaria
• Early prevention of spread of malaria among a colony
• Minimize personnel exposure to malaria
• Safety monitoring of biological products and vaccines that derive from susceptible animals

References:
Cogswell, F.B. (2000) Malaria and Piroplasms of non-human primates. In: Companion and Exotic Animal Parasitology, Bowman D.D. (Ed). A0304.0600.

Preferred specimen: 0.2 ml liver or spleen tissue.

Less preferred specimen: 0.2 ml whole blood in EDTA (purple top) tube.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative real time PCR

Normal range: Nondetected