Surveillance and response strategy in the malaria post-elimination stage: case study of Fujian province.

Malaria used to be a serious health problem in Fujian province in the past, but no local malaria transmission has been found since 2000. In order to eliminate the potential residual cases and prevent re-introduction of malaria so as to achieve the final goal of malaria elimination in Fujian province, various strategy and intervention approaches were tailored to the local settings. For instance, the monitoring of febrile patients by blood smear examinations and vector surveillance and control were strengthened in addition to the routine intervention in the mountainous area of Fujian province, where malaria was highly endemic and the mosquito Anopheles anthropophagus distributed with a high vectorial capacity. There were two local cases who got infected due to imported cases found in the building site of an expressway in 2004 and 2005, respective. All other imported malaria cases were detected during post-elimination stage through surveillance system. Based on results from post-transmission surveillance, malaria transmission has been interrupted in Fujian province for 13 years. Therefore, post-transmission surveillance and response is an important intervention to maintain the malaria elimination achievements in Fujian province.

[Genetic polymorphism of the gene encoding the apical membrane antigen-1 of Plasmodium falciparum].

OBJECTIVE: To study the genetic diversity of apical membrane antigen-1 gene from Plasmodium falciparum (PfAMA-1). METHODS: Filter paper blood samples were collected from 23 imported P. falciparum malaria patients who returned to Fujian Province from 2006 to 2012. Nested PCR were used to amplify the PfAMA-1 gene. The umplified fragments were sequenced, and analyzed by bioinformatic software. RESULTS: All 23 samples were amplified a 505 bp band. Thirty-two nucleotides were found to be variable, resulting in 18 haplotypes. Eight of these 18 halotypes were being reported here for the first time. The parasites collected from Africa showed the higher level of variability [haplotypes diversity (Hd)= 0.0985, nucleotide diversity (π)=0.0258] as compared to the isolates from Asia (Hd=0.909, π=0.0221). The average difference of dN-dS for all 23 PfAMA-1 sequences was 0.031±0.006. Sequence-based neutrality tests were not significant in Africa and Asia (P>0.05). The minimum number of recombination events (Rm) was 10, and the linkage disequilibrium index (R2) evidently declined with the increase of nucleotide distance. A molecular phylogenetic tree constructed using the neighbor-joining method showed that the 23 isolates were assigned to three clades (G1, G2 and G3). Most samples from Africa formed G1, and G3 contained most of Asian isolates. CONCLUSION: Plasmodium falciparum isolates from Africa show a higher genetic diversity than the isolates from Asia for PfAMA-1 gene.

[A case of imported schistosomiasis haematobia first reported in Fujian Province].

The first case of imported schistosomiasis haematobia in Fujian Province was detected and the patient was cured following treatment with praziquantel.

[Determination of rubidium and cesium in chloride type oilfield water by flame atomic absorption spectrometry].

Flame atomic absorption spectrometry (FAAS) was applied to the determination of rubidium and cesium in chloride type oilfield water by considering the interferences of the coexistent K+, Na+, Ca2+, and Mg2+ ions, Standard curve method and standard addition method were compared in the determination of rubidium and cesium in the simulated oilfield water and the real oilfield water from the Nanyishan region in Qaidam Basin. Although rubidium and cesium have similar physical-chemical properties, they present different characters during their analyses using the FAAS technique. When the standard addition method was used for the determination of rubidium and cesium in the simulated oilfield water, the results of rubidium were very poor, whereas the results of cesium were satisfactory. When the standard curve method was used for the determination of rubidium and cesium in the simulated oilfield water, the results of both rubidium and cesium were satisfactory within the linear ranges of the standard curves. For the real oilfield water, standard addition method is also only applicable for the determination of cesium with a recovery ranging from 90% to 110%. While standard curve method is applicable for the determination of both rubidium and cesium with a recovery ranging from 90% to 110%.

[DNA amplification of Plasmodium vivax parasites from Giemsa-stained blood smears].

OBJECTIVE: To develop methods of extracting DNA from malaria parasites on Giemsa-stained blood smears. METHODS: Improved Na2HPO4 method and Chelex-100 ion-exchange technique were used to extract DNA from Giemsa-stained or unstained blood smears. Nested PCR was employed for amplification and identification of allelotype in the Plasmodium vivax merozoite surface protein-1 (PvMSP-1). RESULTS: Target DNA bands appeared in all samples of unstained thick blood smears, while no DNA bands were visible in the fixed and stained thin smears. Both methods identified PvMSP-1 alleles from smears with parasitemia of > or = 0.01%. CONCLUSION: It is feasible to identify PvMSP-1 alleles from Giemsa-stained blood smear.

[Genotype detection of the merozoite surface protein alleles of Plasmodium vivax].

OBJECTIVE: To develop a method for detecting the genotype of Plasmodium vivax merozoite surface protein 1 (PvMSP-1) alleles. METHODS: According to the sequence characteristic of PvMSP-1, nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to amplify the polymorphic region of ICB5-ICB6 which contains Q repeats and PvuII restriction site (Sal-1 type). The PCR product was digested by PvuII restriction endonuclease and the digested fragments were observed by 2% agarose gel electrophoresis. The allelic type was determined according to the banding pattern. RESULTS: Bands in size of 400 bp (Belem type) and/or 470 bp (Sal-1 type) appeared in all 98 P. vivax isolates, no band was found in negative control. After PvuII digestion, two Sal-1 type fragments (120 bp and 350 bp) were obtained from 45 samples of 470 bp. Single-band of 400 bp appeared in 3 of 40 samples with 400 bp as Belem type, two bands of 120 bp and 280 bp appeared from other 35 samples as recombination type III, and another 2 bands with 120 bp and 240 bp as Korean isolate. CONCLUSION: The result showed that the nested PCR-RFLP may be applied in the detection and identification of the three PvMSP-1 allelic types in China.