[Investigation and genetic identification on Babesia infection in rodents in some areas of Fujian Province].

Objective: To explore the status of Babesia infection in rodents and the genetic characteristics of Babesia spp. in Fujian Province. Methods: Rodents were captured by the night trapping method in Shaowu, Qingliu, Shunchang, Yong'an, Changle and Youxi during 2014-2015. The rodent species was identified, and information on the time and place of capture, species and sex of rodents was recorded. Blood samples was collected, in which the fragment of 18S rRNA gene of Babesia spp. was amplified by PCR. The PCR products were sequenced and the phylogenetic tree was constructed for homology analysis. Data on positive rate were analyzed with Chi-square or Fisher exact test. Results: Two hundred and nine rats were captured, comprising of 71 domestic and 138 wild rats. The overall positive rate was 9.6%(20/209). The positive rate in domestic rats was 2.8%(2/71), including one Rattus norvebicus and one Rattus flavipectus. The positive rate in wild rats was 13.0%(18/138), including 13 Bandicota indica, one Rattus losea, 2 Rattus confucianus and 2 Rattus fulvescens. The positive rate was significantly higher in wild rats than in domestic rats (P < 0.05). The Youxi region had the highest positive rate(14.9%,13/87), followed by Yong'an(13.6%, 3/22), and no positive rat was found in Qingliu. The positive rate in the male rats was 7.9%(9/114), and that in the females was 11.6%(11/95). The positive rate was highest in adult rats (10.4%,18/173), followed by young ones (6.3%,2/32). No positive rat was found in old rats. There was no significant difference in positive rate among different regions, between male and female rats, or among different ages (P > 0.05). The sequences of PCR products had a 100% homology. The BLAST results revealed the species to be Babesia microti. The phylogenetic tree showed that the sample sequence was the most homologous with Babesia microti from Zhejiang Province(GenBank Accession No: JQ609305). Conclusion: There occurs Babesia microti infection in rats in part areas of Fujian Province. The positive rate was higher in wild rats than in domestic rats.

The effect of temperature on the extrinsic incubation period and infection rate of dengue virus serotype 2 infection in Aedes albopictus.

Dengue fever is an acute mosquito-borne viral disease caused by dengue virus (DENV). Temperature may affect the efficiency of the mosquito vectors in spreading DENV. Aedes albopictus mosquitoes were infected orally with a DENV2 suspension and incubated at different temperatures. Subsequently, DENV2 antigen was collected from salivary gland and thorax-abdomen samples on different days postinfection and tested using an immunofluorescence assay to determine the extrinsic incubation period and infection rate. As the temperature increased, the extrinsic DENV2 incubation period in Ae. albopictus gradually shortened, and infection rates showed a tendency to initially increase, followed by a subsequent decrease.

[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.