Department of Parasitology-Mycology, Rouen University Hospital, 76 000, Rouen, France.
Department of Pediatrics, Rouen University Hospital, 76 000, Rouen, France.
Malar J. 2017 Aug 15;16(1):339. doi: 10.1186/s12936-017-1979-5.
Since several malaria parasite species are usually present in a particular area, co-infections with more than one species of Plasmodium are more likely to occur in humans infected in these areas. In many mixed infections, parasite densities of the cryptic species may be low and often not recognized in clinical practice.
Two children (3 and 6 years old) adopted recently from Central African Republic were admitted to hospital because of intermittent fever. Thin blood smears stained with Giemsa showed Plasmodium falciparum and Plasmodium malariae co-infection for both children at admission. They were both treated with atovaquone-proguanil combination for 3 days. At day 7, both thin blood smears examination remained negative but at day 28, thin blood smear was positive for P. malariae trophozoites and for Plasmodium ovale for the girl and her brother, respectively. Samples collected at day 1 and day 28 were submitted to real-time PCR showing the presence of the three parasite species (P. falciparum, P malariae and P. ovale) in admission blood samples from the two children and only P. ovale at day 28.
Twenty-eight days follow-up after treatment led to detection of a third parasite species in the blood of these two patients suggesting covert co-infection and a delayed appearance of one cryptic species following treatment. Concurrently infecting malaria species could be mutually suppressive, with P. falciparum tending to dominate other species. These observations provide more evidence that recommendations for treatment of imported malaria should take into account the risk of concurrent or cryptic infection with Plasmodium species. Clinicians and biologists should be aware of the underestimated frequency of mixed infections with cryptic species and of the importance of patient follow-up at day 28. Future guidelines should shed more light on the treatment of mixed infection and on the interest of using artemisinin-based combinations for falciparum and non-falciparum species.
由于在特定地区通常存在多种疟原虫物种，因此在这些地区感染的人类中更有可能发生多种疟原虫的合并感染。在许多混合感染中，隐匿性物种的寄生虫密度可能较低，在临床实践中常常无法识别。
两名（3 岁和 6 岁）最近从中非共和国收养的儿童因间歇性发热而入院。经吉姆萨染色的薄血涂片显示，两名儿童入院时均存在恶性疟原虫和间日疟原虫的合并感染。他们均接受了阿托伐醌-磺胺多辛复方制剂治疗 3 天。第 7 天，两次薄血涂片检查均为阴性，但第 28 天，女孩和她的哥哥的薄血涂片均为间日疟原虫滋养体阳性，女孩的血片中还发现卵形疟原虫。第 1 天和第 28 天采集的样本进行实时 PCR 检测，显示这两名儿童入院时的血液中存在三种寄生虫（恶性疟原虫、间日疟原虫和卵形疟原虫），而在第 28 天仅存在卵形疟原虫。
治疗后 28 天，这两名患者的血液中检测到第三种寄生虫，提示存在隐匿性合并感染，且一种隐匿性物种在治疗后出现延迟。同时感染的疟原虫物种可能相互抑制，恶性疟原虫倾向于主导其他物种。这些观察结果进一步证明，建议对输入性疟疾的治疗应考虑到同时感染或隐匿性感染其他疟原虫的风险。临床医生和生物学家应意识到隐匿性混合感染的频率被低估，并且患者在第 28 天进行随访的重要性。未来的指南应更详细地阐明混合感染的治疗方法，以及使用青蒿素类复方制剂治疗恶性疟原虫和非恶性疟原虫的重要性。
