[Diagnosis and Treatment of the First Imported Case of Plasmodium knowlesi Infection in China].

Objective: To diagnose and treat the first imported active case of Plasmodium knowlesi infection in China. Methods: The clinical information of the patient was collected. Microscopy of blood smear was conducted after Giemsa staining. Genomic DNA was extracted from blood, and PCR was conducted to amplify rDNA. The PCR products were sequenced and analyzed with BLAST Results: The patient returned from a one-week tour in a tropical rain forest in Malaysia. The first disease attack occurred in Guangzhou on Oct. 16, 2014, with fever, shivering and sweating. The patient was initially diagnosed as malaria and hospitalized on Oct. 26, 2014. Microscopic observation revealed typical forms of P. knowlesi in blood smear. The red blood cells became enlarged, with big trophozoites appearing as a ring with dual cores and dark brown malaria pigment. The trophozoites were slightly bigger and thicker than P. falciparum. The schizont had 6-8 merozoites, with obvious brown malaria pigment. PCR resulted in a specific band of 1 099 bp. BLAST analysis showed that the sequence of the PCR product was 99% homologous to P. knowlesi (acession No. AM910985.1, L07560.1 and AY580317.1). The patient was diagnosed as P. knowlesi infection, and was then given an 8-day treatment with chloroquine and primaquine, together with dihydroartemisinin piperaquine phosphate tablet. The patient was discharged after recovery on Oct. 28, 2014. Conclusion: According to the clinical symptoms, epidemiological history and laboratory test, the patient has been confirmed as P. knowlesi infection. It may also be the first active case of knowlesi malaria reported in China.

[Investigation on Angiostrongylus cantonensis infection in rodents in Guangdong Province].

OBJECTIVE: To investigate the natural infection of Angiostrongylus cantonensis in Guangdong Province, and to provide the scientific evidence for control measures. METHODS: The investigation was carried out in 56 villages of 28 towns of 28 counties/districts in East Guangdong, West Guangdong, the mountain area of North Guangdong and Peal River Delta of the Province from 2005 to 2010. The rodents were captured with live trap and the species identified. Angiostrongylus cantonensis adult worms were collected from the hearts and lungs of rodents, examined, counted and the sex of worms identified. RESULTS: The rodents were captured from 2005 to 2010, belonged to 2 orders, 2 families (subfamily), 4 genera and 10 species. Seven species of the rodents were found infected with Angiostrongylus cantonensis in all 28 counties/districts. Totally 5 820 rats were examined and 496 infected ones were identified, with a mean infection rate of 8.52%. The infection rate of rodents was highest in the Peal River Delta, reaching 9.8% (205/2084) (chi2=15.25, P<0.01). Rattus norvegicus had the highest infection rate of 16.9% (310/1 835) (chi2=240.91, P<0.01). The mean intensity of infection was 6.1 worms/rat. 1 125 female and 1064 male worms were found respectively (chi2=1.75, P>0.05). CONCLUSION: Natural infection of Angiostrongylus cantonensis in rodents has been found in all the 56 villages selected from the 4 regions of Guangdong Province.

[Survey on the focus of Angiostrongylus cantonensis in Guangdong Province].

OBJECTIVE: To understand the distribution of Angiostrongylus cantonensis foci in Guangdong Province for making surveillance program. METHODS: Survey sites were chosen by strata sampling according to different geographic locations. Totally 22 survey sites were selected in four regions: East Guangdong, West Guangdong, North Guangdong and the Pearl River Delta. One or two administrative villages in each site were randomly selected for the investigation. Pomacea canaliculata and Achatina fulica collected from fields and other species of freshwater or terrestrial snails obtained in the restaurants and wet markets were examined for the third stage larvae by tissue grinding or lung examination. Rats were captured in the fields, and their hearts and lungs were dissected for adult worms. Rat feces were also collected for the detection of first stage larvae by water precipitation. RESULTS: Large number of P. canaliculata was found in all sites. A. fulica was found in most surveyed sites. Totally 2929 P. canaliculata and 1354 A. fulica were collected with a larva infection rate of 5.9% (172/2929) and 16.5% (223/1354), respectively (P<0.01). The average prevalence among the regions was different (P<0.01) with the highest prevalence in Pearl River Delta (15.6%, 152/975), especially in Dongguan City of the Delta (34.7%, 78/225). 114 Cipangopaludina sp. and 252 Bellamya sp. were bought from wet markets of 9. sites. Larvae were found only in Bellamya snails from Luoding and Kaiping cities with an infection rate of 1.4% (1/70) and 3.3% (3/91), respectively. Totally 491 rats were captured in 9 sites including Rattus norvegicus, R. flavipectus, Suncus murinus, Mus musculus, Bandicota indica, R. losea and R. rattus, with an average infection rate of 11.4% (56/491). Adult worms were found in R. norvegicus, R. flavipectus and B. indica with a prevalence of 19.8% (52/263), 2.5% (3/118) and 10.0% (1/10), respectively. Thirty-four rodent fecal samples were collected in 7 sites and examined with a larva positive rate of 44.1% (15/34). CONCLUSION: Foci of Angiostrongylus cantonensis are widely distributed in Guangdong Province as natural infection has been found in its intermediate and definitive hosts.

[Current prevalence of Clonorchis sinensis infection in endemic areas of China].

OBJECTIVE: To investigate the current prevalence of Clonorchis sinensis infection in the known endemic areas of China. METHODS: According to different endemic level and river system, the lamination stochastic group sampling was carried out in 27 Provinces/Municipalities/Autonomous Regions (P/M/A) from 2002 to 2004. Eggs in stool were examined by modified Kato-Katz thick smears method. RESULT: A total of 5,230 cases of Clonorchis infection was found from 217,829 sampled population of 27 P/M/A, and the mean prevalence was 2.40% by which the number of infected people was estimated to be 12.49 millions. The geometry mean worm egg density was 2,208 EPG (stool). Light, moderate and heavy infection occupied 78.93%, 17.40%, and 3.67% respectively. Infection was found in 19 out of 27 P/M/A investigated, with the highest prevalence in the provinces of Guangdong (16.42%, 2,278/13,876), Guangxi (9.75%, 1,365/13,990) and Heilongjiang (4.72%, 636/13,458). Males showed higher prevalence (2.94%, 3,267/111,262) than females (1.84%, 1,963/106,567). There was infection in all age groups,with the highest prevalence in the group of 50 to 59 years (9.16%). By occupations, more infections were found in businessmen (13.42%, 124/924), followed by factory workers ((7.9%, 298/3,773), and retirees and veterans (5.28%, 70/1,327). Adults showed heavier infection in some provinces where the main infection way was raw fish-eating, but in children in other provinces. For geographical distribution, the terrain in network of rivers and lakes showed higher prevalence (5.23%, 687/13,125) than the hilly terrain (2.34%, 1,111/47,552). Prevalence showed family-aggregation feature. CONCLUSION: Clonorchiasis is widely endemic in China with a high prevalence in some provinces. Male adults have been more involved with a family aggregation.

[Follow-up survey on the imported cases of lymphatic filariasis in Guangdong Province].

OBJECTIVE: To make a survey on the possible imported cases with microfilaremia from a recently identified outbreak focus in Fuchuan County of Guangxi Region. METHODS: Moving people as temporary laborers from Guangxi and periphery residents were screened by thick blood smears for microfilariae and ELISA for specific IgG4 in Sept 2007. RESULTS: 989 persons in cities/districts of Nansha, Panyu, Shantou and Zhongshan were investigated. Among 150 persons from Changtang administrative village of Guangxi, 47 were from two outbreak focuses, Ganshang and Yinshan natural villages in Changtang. Three cases with microfilaremia were found, with a microfilaraemia density of 24, 20 and 2 per 120 microl blood, respectively. The 3 cases were all from the 2 natural villages, with a microfilaraemia positive rate of 6.4% (3/47). Meanwhile, anti-filaria IgG4 was detected for other 1 501 persons, including those from the outbreak focuses, from surr-founding areas and from non-endemic area as control, fifteen cases were found with IgG4 positive. Of the 15 positive cases, 12 were from the 2 outbreak natural villages, with a positive rate of 25.5%, higher than those of others (chi2=295.83, P < 0.01). The cases with IgG4 positive but microfilaremia negative were reexamined by ICT kit and all showed negative. CONCLUSION: It is suggested that no further transmission occurs although microfilaremia cases have been imported from the outbreak focus of Guangxi.

Risk factors for Enterobius vermicularis infection in children in Gaozhou, Guangdong, China.

BACKGROUND: Enterobius vermicularis infection is a prevalent intestinal parasitic disease in children. In this study, we explored the epidemiological status and risk factors for E. vermicularis infection in children in southern China. METHODS: A cross-sectional survey was carried out in Gaozhou city, Guangdong province, China, in December 2011. Children aged 2-12 years from five schools participated in the study. The adhesive cellophane-tape perianal swab method was applied to detect E. vermicularis infection, while a questionnaire was sent to each child's guardian(s) to collect demographic and socioeconomic data, as well as hygiene behaviors, pertaining to each child. Univariate and multivariate logistic regression analyses were performed to capture the potential risk factors. RESULTS: Out of the 802 children surveyed, 440 were infected with E. vermicularis, with an average prevalence of 54.86 %, and a range from 45.96 to 68.13 %. The age variable was found to be statistically significant, whereas the sex variable was not. It was found that a mother's education level (low) and not washing hands before dinner were major risk factors in all children (802). After stratification by age, a father's education level (primary or below) and biting pencils (or toys) were significant risk factors in the younger children (508), while not washing hands before dinner and playing on the ground were important risk factors in the older children (294). CONCLUSION: This study demonstrates the prevalence of E. vermicularis infection in children in Gaozhou and reveals underlying risk factors. Most importantly, it reveals that risk factors differ among the different age groups, which indicates that different control measures targeted at particular age groups should be implemented.

[Research on chemotherapy measures in different Clonorchis sinensis infectiosity endemic areas].

OBJECTIVE: To explore the suitable chemotherapy measures in different Clonorchis sinensis infectiosity endemic areas. METHODS: The interventional groups and control groups were set up in the heavy, moderate and light C. sinensis infectiosity areas in Guangdong Province, respectively. In the intervention groups, the chemotherapy was administered among all the residents aged above 3 years in the heavy endemic areas, the chemotherapy was given among the focus populations in the moderate endemic areas, and the chemotherapy was administered among the residents infected with C. sinensis confirmed by stool examinations in the light endemic areas. No measures were carried out in the control groups. RESULTS: One year after the interventions, the C. sinensis infection rates of the interventional groups decreased by 47.90%, 86.52% and 100%, the abnormal rates of liver B ultrasonic examinations decreased by 26.50%, 31.00% and 100%, the ALT abnormal rates decreased by 48.70%, 62.30% and 100%, and the AST abnormal rates decreased by 55.50%, 39.90% and 100% in the heavy, moderate and light endemic areas, respectively. There was no decreasing trend of above-mentioned indexes in the control groups. CONCLUSION: In the different C. sinensis infectiosity endemic areas, the different chemotherapy measures should be carried out.

[Epidemiological analysis of malaria epidemic situation in Guangdong Province, 2011].

OBJECTIVE: To analyze the features of malaria epidemic in Guangdong Province in 2011 so as to provide the evidence for the elimination of malaria in Guangdong Province. METHODS: The data from the Disease Reporting Information System of Chinese Center for Disease Control and Prevention were analyzed with the descriptive epidemiological method for the epidemiological characteristics of malaria in Guangdong Province in 2011. RESULTS: A total of 96 malaria cases were reported in Guangdong Province in 2011, with an annual mean incidence of 0.092 per 100 thousand. There were 40 cases of Plasmodium vivax infection, 36 cases of Plasmodium falciparum infection and 20 cases of undivided malaria. There were 2 death cases. There were cases reported in 34 counties/cities/districts of 17 prefecture-level cities in the whole province. The cases distributed mainly in Guangzhou and Shenzhen, where there were 57 cases, reaching 59.38% of the cases of the whole province. There were cases reported every month in the whole year. From May to November, 73 cases were reported, accounting for 76.04% of the cases of the whole year. The ratio of male to female cases was 5.86: 1. The age distribution concentrated mainly on 20-50 years old. The youngest patient was 1 years old and the eldest was 65 years old. The occupation distribution concentrated mainly on the worker, commercial service, peasant, housekeeper and unemployed people (68 cases, 70.83%). In addition to the aforementioned 96 cases of local census register population, there were 32 cases of nonlocal census register population found in Guangdong, 2011. Of the total 128 cases, the main original areas of the imported cases were Africa (77, 60.16%) and Asia (30, 23.44%). The country with the most cases was Nigeria in Africa (36 cases), the second was Angola in Africa (19 cases), and the third was Myanmar in Asia (11 cases). CONCLUSION: The malaria epidemic situation in Guangdong Province is relatively stable in 2011, but the imported cases of Plasmodium falciparum infection increase. Therefore, the surveillance, prevention and control for imported cases of P. falciparum infection should be strengthened.

[Survey of distribution of Enterobius vermicularis infection of children in Huadu District, Guangzhou City].

OBJECTIVE: To understand the status of Enterobius vermicularis infection of children in Huadu District, Guangzhou City so as to provide the evidence for improving the control work. METHODS: In 2012, 24 kindergartens and 24 primary schools were selected as survey sites by the stratified random sampling method and 200 or more children aged below 10 years per site were investigated for the Enterobius vermicularis infection by the cellophane tape method. The relevant influencing factors (environment conditions, sanitary facilities and management system, and health habits of families and individuals) were surveyed with questionnaire, and all the data were analyzed statistically with the Excel software. RESULTS: From September to December, 2012, totally 9 777 children were investigated and 760 ones were detected with Enterobius vermicularis infection (7.77%). With a school as the unit, the highest infection rate reached to 33.82% (69/204). The infection rate in urban areas was 4.63% (195/ 4 213), and the rate in villages was 10.15% (760/5 546) ( chi2 =102.126, P <0.01). The infection rate of preschool children was 3.51% (1 70/4 840) and the rate of school children was 11.95% (590/4 973), and the latter was much higher than the former (chi2 =242.732, P < 0.01). The infection rates of the male and the female were 7.44% (412/5 537) and 8.21% (348/4, 240) respectively ( chi2 = 1.969, P > 0.05). The survey of relevant influencing factors showed that the conditions of the kindergartens were better than those in the primary schools, and the conditions in the urban areas were better than those in the villages. CONCLUSIONS: The Enterobius vermicularis infection of children in Huadu District is high. The control key points should be put on the schools with poor sanitary facilities and environment conditions in villages and urban areas.

[Endemic situation of schistosomiasis in Guangdong Province from 2004 to 2009].

OBJECTIVE: To understand the endemic situation of schistosomiasis in Guangdong Province. METHODS: The surveillance of Oncomelania hupensis snails and infectious sources was carried out in the former endemic areas, and the surveillance data were statistically analyzed from 2004 to 2009 according to the national and provincial surveillance protocols. RESULTS: From 2004 to 2009, an area of 927.45 hm2 was surveyed and no living snails were found, and 287 out of 12 345 young people living in the endemic areas showed serum positive with the DIGFA, but none of schistosomiasis patients were found. A total of 28 766 mobile population were involved in the DIGFA examination, and 417 persons were positive, among them, 52 chronic patients were found, and 6 patients had eggs in their stools. Through the passive surveillance, 281 cases were reported from 2003 to 2009, and 4 acute cases were reported from 2004 (1 case) to 2005 (3 cases). A total of 9 064 head of cattle were surveyed and none of them was infected with Schistosoma japonicum by stool examination. CONCLUSIONS: The achievements of schistosomiasis control are solidified in Guangdong Province. However, the risk of schistosomiasis transmission still remains. The surveillance should be continued, especially of imported infectious sources and snails.