| Objective:To ascertain the epidemic features of malaria, the status of resistance to an-timalarias and the therapeutic efficacy of Plasmodium falciparum in Laiza City of Myanmar where bordering on China. So as to provide basis data to the sixth round of the China Global Fund malaria project for formulating related prevention strategy. Methods: A research station was established in downtown of Laiza City to screen and detect mala-ria patients by blood microscopic examination among the febrile and/or suspected mala-ria patients in a whole year. The downtown and four suburban natural villages of Laiza City were studied as the research objects for doing the malaria epidemiological analysis. Patients with P. falciparum mono-infection and without clinical complications, who are living in study areas, were selected into the studies of resistance to antimalarias. An in vitro micro-test recommended by the WHO was conducted to assay the susceptibility of P. falciparum to six kinds of antimalarias.2one-arm in vivo tests recommended by the WHO were conducted to assess the therapeutic efficacy of the standard treatment regi-men of dihydroartemisinin/piperaquine (DHP) and artesunate for treating uncomplicated falciparum malaria, respectively. Patients were followed-up28days and the treatment failure as "recrudescence" was distinguished with re-infection by PCR to adjust the re-sults of treatment. Results:A total of3050cases were examined and the annual positive rate of blood examination in all cases and the floating population was31.2%and30.0%respectively. The annual malaria incidence of Laiza City, downtown and suburban natural villages of Laiza City was11.2%,8.9%and21.0%, respectively. Malaria prevailed throughout the year with two peaks in June and August.4human malaria species were detected and P. falciparum was predominant species counted for58.1%, P.vivax counted for39%, the two other were accidental species. The malaria incidence of male population was1.6times higher than female and the15≤Y<20age group had the most malaria pa-tients.27of43cases were successfully assayed by in vitro micro-test. The resistance rate of chloroquine, piperaquine, pyrondridin, artesunate, dihydroartemisinin and dihydroar-temisinin/Piperaquine was100%,0%,25.9%,22.2%,7.4%and0%, respectively. The50% inhibiting concentration (IC50) was298.0,49.4,22.3,11.8and5.6/44.8nmol/L.64of74enrolled and49of65enrolled were observed by in the in vivo test of DHP and artesunate, respectively. The therapeutic efficacy was100%adequate clinical and parasitological responses in DHP test. However,6.3%of observed patients had parasitemia on day3.Two cases treated failure as recrudescence and the rate of treated failure was4.1%in artesunate test. These2were confirmed as re-infection by PCR and the therapeutic effi-cacy was adjusted to100%adequate clinical and parasitological responses. However,25.4%of observed patients on day3and4.1%on Day had parasitemia. Conclusion: The prevalence of malaria is serious in Laiza City. There belongs to malaria intense transmission areas and P. falciparum is predominant species. The status of malaria situa-tion in Laiza City is serious threaten the border areas and the outbound floating popula-tion of china. P.falciparum has100%resistance to chloroquine in this area. Meanwhile, it has a certain extent resistance to pyrondridin, artesunate and dihydroartemisinin. The de-gree of resistance to chloroquine, pyrondridin and artesunate are gradually tending to in-crease But it is susceptibility to piperaquine and dihydroartemisinin/Piperaquine. For treating falciparum malaria, both DHP and artesunate are efficacious and safe, but arte-sunate more slowly clears the parasitemia. P.falciparum tolerance to artesunate exists, but there is not enough evidence to prove P. falciparum resistance to artesunate exists in population in Laiza City. |
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