[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.

[Survey on the current status of important human parasitic infections in Fujian province].

OBJECTIVE: To understand the prevalence of important human parasitic diseases in Fujian province. METHODS: According to the national guidelines, clustered random sampling was made for the survey. Modified Kato-Katz thick smear was applied to examine helminth eggs for soil-transmitted nematodes and Clonorchis sinensis. Cellophane and swab technique was applied for detecting Enterobius vermicularis eggs in children under 12. Questionnairing, skin test, serological test and eosinophil examination were carried out for Paragonimus infection. Questionnairing and serological test were used for Taenia infection and cysticercosis. Retrospective investigation was conducted with the data on outpatient and hospitalized cases with parasitic diseases. RESULTS: 45,736 people at 73 spots of 24 counties were investigated and 14 species of parasites were found. The overall infection rate of intestinal helminth infections was 36.15%. The prevalence of Ascaris lumbricoides, hookworms and Trichuris trichiura was 9.55%, 19.73% and 11.48% respectively. The infection rate of Enterobius vermicularis and Clonorchis sinensis was 22.06% and 0.60% respectively. The positive rate of skin test and serological test among skin test positives for Paragonimus infection was 7.07% and 9.23% respectively. The serology positive rate for cysticercosis was 2.28%, only 3 cases of taenia infection were found from 16371 persons investigated. Human infections with Angiostrongylus cantonensis, Diphyllobothrium latus, Taenia saginata, and Gnathostoma spinigerum were found for the first time in the Province. Metorchis orientalis and Echinostoma aegyptiaca infections in human were first recorded. CONCLUSION: The overall prevalence of soil-transmitted nematodes has decreased significantly in the province, although still highly prevalent in social-economically less developed areas. Meanwhile, attention should be paid to the food-borne parasitic infections in human population.

[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.

[Morphological observation of Haplorchis pumilio].

OBJECTIVE: To provide the basis for the differentiation with similar species of intestinal flukes through observing the figure of Haplorchis pumilio. METHODS: Adults of H. pumilio were collected from the intestine of the cat which was infected with the encysted cercariae of H. pumilio for 45 days. The worms were observed after staining. Eggs and metacercariae of H. pumilio were collected and examined for their shape, size and morphological characteristics. Pseudorasbora parva, the fish host, was examined for the parasitized sites of metacercariae. RESULTS: The principal characteristics of the adults is the acetabulum degradation. There are only the genital sucker with 44-48 hamuli. The average measurement of eggs is 31.2 x 16.7 microns with a smooth shell. Its aceromion is not evident. The average diameter of metacercariae is 168.5 microns. There are squamous spines on metacercaria. The metacercariae only parasitize in the muscle between the basis of the fin and the fish body. The average measurement of metacercaria cyst is 445 x 95 microns, with squamous spines on the body surface. Hamuli are found on the genital sucker of metacercaria cyst. CONCLUSION: The morphological figures and parasitic sites of metacercaria, the genital sucker of the adult, and the number and form of the hamulus on the genital sucker provide basis for distinguishing H. pumilio from other intestinal flukes.

[Study on the public health emergent events in Fujian province in 2004--2007].

OBJECTIVE: To study the public health emergent events (PHEE) in Fujian province, from 2004 to 2007. METHODS: Descriptive and analytic methods were used to analyze the PHEE in Fujian province according to the internet-based surveillance reports. RESULTS: From 2004 to 2007, there were 304 emergency events being surveyed. Of all the events, there were 7 (2.30%) belonged to serious-degree of grade II, 57(18.75%) to grade III and 240 (78.95%) to grade IV, but with no grade I. Results showed that the attack rate in affected population was 25.82 per thousand, the mortality rate was 0.08 per thousand and the fatality rate was 0.32%. The numbers of emergency events decreased 2.82% on average, each year. A total number of 169 (55.60%) events occurred in schools with 71 (23.36%) in the countryside. Numbers due to infectious disease-born was 233 (76.64%) including avian flu, cholera and dengue fever were predominant pathogens of the grade II and grade III emergency events. 57 (18.75%) of the events was due to food poisoning. The epi-garph showed that there were two peaks. i.e. in Mar-Apr and Sep, contributed 43.1% to the total number of events. CONCLUSION: Emergency events showed a stable decrease in Fujian province with communicable disease and food poisoning the two major sources and more commonly seen in schools and countryside. We suggest that the government and community pay more attention to the emergency events of avian flu, cholera and dengue fever.

[Study on the epidemiology and etiologic agent of Dengue fever outbreaks in Fuzhou in 2004].

OBJECTIVE: To study the epidemiology and etiologic characteristics of a Dengue fever outbreak in Fuzhou from the beginning of September to the end of October in 2004 in order to understand the source of infection. METHODS: Data on descriptive epidemiology was collected to study the characteristics and related factors to the epidemic. Dengue virus was isolated through the use of C6/36 cell line while viral serotypes were identified by indirect immunofluorecent assay with type-specific monoclonal antibody. The sources of infection were traced by nucleotide sequencing. RESULTS: During the epidemic, 93 cases occured consistently with the region entomoplily growth and decay. The viruses of 6 strains isolated from 10 patients' blood specimens were identified as dengue virus type 1. Phylogenetic evidence suggested that the viral isolate had high genetic relation with the isolates from Kampuchea (DENV-1/KHM/2001; GenBank Accession No. L0904278). CONCLUSION: The epidemic was caused by introduction of patients migrating into Fuzhou.

[Study on the timeliness of the notifiable communicable diseases surveillance system in Fujian province, China, 2004].

OBJECTIVE: To understand the timeliness of the notifiable communicable diseases surveillance system in Fujian province. METHODS: Database from the internet based communicable diseases reporting system was used. RESULTS: The 50th percentile of time between the disease diagnosed and report recorded in medical faculties was 1 day in 2004 which was 6 days less than that in 2001 - 2003. The timeliness rate of 0 day was 46.46%, a 2.7 times over that in 2001 - 2003. The timeliness of notifiable communicable diseases surveillance system in different administrative areas, reporting units and on different diseases was significantly different. Time between the disease diagnosed and report recorded was the shortest in those cases reported by hospitals and traditional Chinese medicine(TCM) hospitals at the county level and above, with 50th percentile as 0 day, but the timeliness rate of 0 day was 50.76% with 70.04% of the cases were reported from hospitals and TCM hospitals of county level and above. Length between the disease diagnosed and reported was the longest in those cases recorded by Centers for Disease Control and Prevention(CDCs) with the 50th percentile as 3 days. The source of cases recorded by CDCs came from hospitals at the township level, where there was no connection to internet but the reporting cards had to be sent to local CDCs. Time between the disease being diagnosed and reported was 2 days in those cases reported by hospitals at the township level. 21.21% of cases were recorded by hospitals of township level and CDCs. The 50th percentile of time shown between the reported records and confirmed by CDCs was 4 hours The 24 hour timeliness rate was 63.65%. CONCLUSION: The timeliness of the notifiable communicable diseases surveillance system had been improved significantly after the medical personnel recording the cases directly through internet. Timeliness could be further improved through access to internet at the hospitals of township level, training of staff and better hospital management systems.