Prolonged parasite clearance in a Chinese splenectomized patient with falciparum malaria imported from Nigeria

Abstract

BackgroundThe spleen plays a pivotal role in the rapid clearance of parasitized red blood cells in patients with falciparum malaria after artemisinin treatment. Prolonged parasite clearance can be found in patients who have had a splenectomy, or those with hemoglobin abnormalities and/or reduced immunity, which are all distinguishable from artemisinin resistance. This paper reports on a case of prolonged parasite clearance in a Chinese splenectomized patient with falciparum malaria imported from Nigeria.Case presentationA 35-year-old Chinese male suffered 2 days of febrile illness after returning to Zhumadian city of Henan province from Nigeria on October 1, 2014. The main symptoms were febrile, including the highest axillary temperature of 40 °C, headache, and chills. A peripheral blood smear showed parasitemia (53 913 asexual parasites/μl) of Plasmodium falciparum. The patient had not used any chemoprophylaxis against malaria in Nigeria when he worked there as a construction worker between 2009 and 2014. The patient had three episodes of malaria in Nigeria and had a splenectomy due to a traffic accident 8 years ago from the time he was admitted to hospital. The patient was orally administrated a total of 320 mg/2.56 g dihydroartemisinin-piperaquine for 2 days and intravenously administrated a total of 3 000 mg artesunate for 18 days. The axillary temperature of the patient ranged between 37.0 and 37.7 °C from Day 0 to Day 3, and blood microscopy revealed falciparum malaria parasitemia (26 674 asexual parasites/μl) on Day 3. The patient was afebrile on Day 4, falciparum malaria parasitemia was continuously present and then gradually decreased on the next days, and was negative on Day 21. The patient was cured and left hospital on Day 24 after no plasmodium falciparum was found in the blood on Day 21 to Day 23. No mutation was found in the K13 propeller gene when compared with the PF3D7_1343700 K13 propeller gene reference sequence.ConclusionsThis is the first reported case in China of prolonged parasite clearance in a splenectomized patient with imported falciparum malaria. Artemisinin resistance should be distinguished when prolonged parasite clearance is found in a malaria patient who has had splenectomy.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-017-0259-5) contains supplementary material, which is available to authorized users.

The spleen: “epicenter” in malaria infection and immunity

“…Also, mature forms of the parasite are more frequently found in the blood, suggesting a lack of sequestration or an inability to clear the parasites in the spleen's absence. 15,[40][41][42][43] In support of the former, a splenectomized patient from Cameroon displayed high parasitemia and the presence of late trophozoites, schizonts, and gametocytes in circulation. RT-PCR analysis on the blood indicated that pRBCs from the patient failed to express members of the var, rifin, and stevor multigene families, and pRBCs failed to bind to host receptors such as CD36 and ICAM-1 in vitro.…”

“…During primary infection with P. falciparum , the severity of disease (i.e., increased cerebral malaria), death, and parasite burden are enhanced in splenectomized patients. Also, mature forms of the parasite are more frequently found in the blood, suggesting a lack of sequestration or an inability to clear the parasites in the spleen's absence 15,40–43 . In support of the former, a splenectomized patient from Cameroon displayed high parasitemia and the presence of late trophozoites, schizonts, and gametocytes in circulation.…”

Prevalence of potential mediators of artemisinin resistance in African isolates of Plasmodium falciparum

“…It has a coiled-coil-containing (CCC; amino acid from 212-341), broadcomplex, tram track, and bric-a-brac (BTB; amino acid from 350-437) and a C-terminal kelch-repeat propeller (KREP; amino acid from 443-726) which harbours virtually all Pfk13 allelic variants associated with artemisinin resistance (Anderson et al, 2017) (Figure 5). Kelch-13 gene is putatively associated with intraerythrocytic growth and proliferation of both P. falciparum asexual parasites (Bushell et al, 2017;Zhang et al, 2017).…”

High Risk of Plasmodium vivax Malaria Following Splenectomy in Papua, Indonesia

“…Several case reports and small series highlight an increased risk of malaria after splenectomy, however these reports are limited to no more than 33 splenectomized individuals [1, 2, 12–14, 22–26]. The current analysis was able to expand the risk analysis from an endemic area where a high number of individuals undergo splenectomy, mostly following trauma or road traffic injuries.…”

“…The spleen is vital for immunity to Plasmodium species [1, 7–11]. Splenectomized patients are more susceptible to severe falciparum malaria and have a greater risk of hospitalization and mortality [12–14]. Studies of splenectomized individuals in malaria-endemic regions of Malawi and Papua New Guinea suggest a risk of malaria almost double that of non-splenectomized controls [1, 2].…”