Yunnan Institute of Parasitic Diseases

Puer, China

Yunnan Institute of Parasitic Diseases

Puer, China

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Xu J.-W.,Yunnan Institute of Parasitic Diseases | Liu H.,Yunnan Institute of Parasitic Diseases
Malaria Journal | Year: 2016

Background: Understanding malaria along the international border of two countries is important for malaria control and elimination; however, it is difficult to investigate a quantitative relationship between two countries' border areas due to a shortage of malaria surveillance data. Methods: A linear regression analysis was conducted to investigate the logarithmic annual parasite incidence (API), numbers of imported cases and local infections in 19 Chinese border counties, with logarithmic API and parasitic prevalence in Myanmar's five special regions. Results: API in 19 Chinese counties was stronger correlated with parasite prevalence than with API in five special regions of Myanmar, correlation coefficient (R) 0.8322 (95 % CI 0.0636-0.9084) versus 0.9914 (95 % CI 0.9204-0.9914). Numbers of imported malaria cases and local malaria infections in 19 Chinese counties were also closer correlated with parasite prevalence than with API in five special regions of Myanmar. Conclusions: There is a strong correlation of malaria between China's side and Myanmar's side along the international border. Parasite prevalence is a better indicator of the true malaria situation in a setting without sound surveillance and reporting system. China should reconsider its definition of imported malaria which neglects imported malaria by mosquitoes and asymptomatic parasite carriers. © 2016 The Author(s).

Zuo S.,Beijing Institute of Microbiology and Epidemiology | Zhao Q.,Beijing Institute of Microbiology and Epidemiology | Guo X.,Yunnan Institute of Parasitic Diseases | Zhou H.,Yunnan Institute of Parasitic Diseases | And 2 more authors.
Virus Research | Year: 2014

Flaviviruses present a wide range of genetic diversity and exhibit diverse host relationships. Mosquito-borne flaviviruses have recently been isolated and characterized worldwide. Yunnan Province of China is one of the richest areas of species diversity and is the center of multi-species evolution in mainland Asia, which supports the circulation of numerous arthropod-borne viruses (arboviruses). In a screening program of arboviruses, mosquitoes were collected during the mosquito activity season in the Yunnan Province from 2007 to 2010. Eleven flavivirus strains, named Yunnan Culex flaviviruses (YNCxFVs), were obtained from Culex tritaeniorhynchus and Anopheles sinensis specimens. Sequence analyses based on partial nonstructural protein (NS) 5 gene indicated that the YNCxFVs shared 92.8-99.6% nucleotide identity with each other and were similar to the Culex-related flaviviruses. The complete genome of one representative isolate, LSFlaviV-A20-09, was sequenced. The genome was 10,865 nucleotides long and contained a single, long open reading frame (ORF) of 10,080 nucleotides that encoded a 3360-aa polyprotein. This genome was most closely related to the Quang Binh virus (QBV) VN180 strain, an insect-specific flavivirus isolated from Culex mosquitoes in Vietnam, but only had 83.0% nucleotide and 93.8% amino acid identities for the ORF sequence. The genome has approximately 66.3%-68.5% nucleotide sequence and 69.3-73.3% amino acid sequence identities to other Culex flaviviruses, and only has 47.9-57.9% nucleotide sequence and 38.7-55.1% amino acid sequence identities to Coquillettidia-related, Mansonia-related and Aedes-related flaviviruses. Phylogenetic analyses revealed that the LSFlaviV-A20-09 fell into the Culex-related flavivirus clade. Our discoveries provide more information regarding the heterogeneity of viruses that infect mosquitoes. © 2013 Elsevier B.V.

Xu J.,Yunnan Institute of Parasitic Diseases | Liu H.,Yunnan Institute of Parasitic Diseases
Southeast Asian Journal of Tropical Medicine and Public Health | Year: 2012

China launched a Malaria Elimination Action Plan for 2010-2020. Yunnan, a province along the western border of China, belongs to the Great Mekong Subregion. Malaria elimination in the Great Mekong Region is a great challenge. We chose Yunnan to analyze the challenges for malaria elimination and how to overcome the barriers for malaria elimination globally.

Chen G.W.,Yunnan Institute of Parasitic Diseases
Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases | Year: 2011

Malaria situation in 5 monitoring sites of Yunnan showed a decline trend from 2005 to 2008. The average malaria incidence in 2008 was 11.84/10,000 with a decrease of 66.1% in comparison to 2005. The seropositive rate with immuno-fluorescence assay (IFA) was 4.61% for pupils. 82% of the cases chose town or township hospitals as the first place of seeking diagnosis and treatment. 83.6% cases were diagnosed over 3 days of symptom appearing. The main clinical manifestation was fever every other day attack (occupied 72.7%). 98.4% of the cases were with light symptoms. The proportion of primary attacks and relapses among malaria patients were 95.3% and 4.7%, respectively. Plasmodium vivax was the main malaria parasite, occupying 81.2%. 97.2% of the local infected cases were found in the bordering areas of the country. The mosquito net utilization rate was 51.4%. Results showed that malaria has been effectively controlled in the monitoring sites of Yunnan.

Huang F.,National Institute of Parasitic Diseases | Tang L.,National Institute of Parasitic Diseases | Yang H.,Yunnan Institute of Parasitic Diseases | Zhou S.,National Institute of Parasitic Diseases | And 2 more authors.
Malaria Journal | Year: 2012

Background: The aim of this study was to evaluate the clinical outcome after seven-day artesunate monotherapy for uncomplicated Plasmodium falciparum malaria in Yingjiang County along the China-Myanmar border and investigate genetic polymorphisms in the P. falciparum chloroquine-resistance transporter (pfcrt), multidrug resistance 1 (pfmdr1), dihydrofolate reductase (pfdhfr), dihydropteroate synthase (pfdhps) and ATPase (pfatp6) genes. Methods. Patientsone year of age with fever (axillary temperature 37.5°C) or history of fever and P. falciparum mono-infection were included. Patients received anti-malarial treatment with artesunate (total dose of 16mg/kg over seven days) by directly observed therapy. After a 28-day follow-up, treatment efficacy and effectiveness were assessed based on clinical and parasitological outcomes. Treatment failure was defined as recrudescence of the original parasite and distinguished with new infection confirmed by PCR. Analysis of gene mutation and amplification were performed by nested polymerase chain reaction. Results: Sixty-five patients were enrolled; 10 withdrew from the study, and six were lost to follow-up. All but two patients demonstrated adequate clinical and parasitological response; 12 had detectable parasitaemia on day 3. These two patients were confirmed to be new infection by PCR. The efficacy of artesunate was 95.9%. The pfcrt mutation in codon 76 was found in all isolates (100%), and mutations in codons 71 and 72 were found in 4.8% of parasite isolates. No mutation of pfmdr1 (codons 86 or 1246) was found. Among all samples, 5.1% were wild type for pfdhfr, whereas the other samples had mutations in four codons (51, 59, 108 and 164), and mutations in pfdhps (codons 436, 437, 540 and 581) were found in all isolates. No samples had mutations in pfatp6 codons 623 or 769, but two new mutations (N683K and R756K) were found in 4.6% and 9.2% of parasite isolates, respectively. Conclusion: Plasmodium falciparum infection was associated with slow parasite clearance and suspected artemisinin resistance at the China-Myanmar border area. The prevalence of pfcrt 76T and markers for SP resistance are still high. It should be strengthened further on parasite clearance time or clearance half life to confirm the resistance status, and molecular epidemiology should provide complementary information to assess the appropriateness of current policies based on artemisinin derivatives. © 2012 Huang et al.; licensee BioMed Central Ltd.

Xu J.-W.,Yunnan Institute of Parasitic Diseases | Liu H.,Yunnan Institute of Parasitic Diseases | Nie R.-H.,Yunnan Institute of Parasitic Diseases | Havumaki J.,Foundation for Innovative New Diagnostics
PLoS ONE | Year: 2014

Background: Insecticide-treated nets (ITNs) are an integral part of vector control recommendations for malaria elimination in China. This study investigated the extent to which bed nets were used and which factors influence bed net use among Jinuo Ethnic Minority in China-Myanmar-Laos border areas. Methods and Findings: This study combined a quantitative household questionnaire survey and qualitative semi-structured in-depth interviews (SDI). Questionnaires were administered to 352 heads of households. SDIs were given to 20 key informants. The bed net to person ratio was 1:2.1 (i.e., nearly one net for every two people), however only 169 (48.0%) households owned at least one net and 623 (47.2%) residents slept under bed nets the prior night. The percentages of residents who regularly slept under nets (RSUN) and slept under nets the prior night (SUNPN) were similar (48.0% vs. 47.2%, P>0.05), however the percentage correct use of nets (CUN) was significantly lower (34.5%, P<0.0001). The annual cash income per person (ACIP) was an independent factor that influenced bed net use (P<0.0001), where families with an ACIP of CNY10000 or more were much more likely to use nets. House type was strongly associated with bed net use (OR: 4.71, 95% CI: 2.81, 7.91; P<0.0001), where those with traditional wood walls and terracotta roofs were significantly more likely to use nets, and the head of household's knowledge was an independent factor (OR: 5.04, 95% CI: 2.72, 9.35; P<0.0001), where those who knew bed nets prevent malaria were significantly more likely to use nets too. Conclusions: High bed net availability does not necessarily mean higher coverage or bed net use. Household income, house type and knowledge of the ability of bed nets to prevent malaria are all independent factors that influence bed net use among Jinuo Ethnic Minority. © 2014 Xu et al.

Cheng Z.,Peking Union Medical College | Sun X.,Yunnan Institute of Parasitic Diseases | Yang Y.,Peking Union Medical College | Wang H.,Peking Union Medical College | Zheng Z.,Peking Union Medical College
Journal of Clinical Microbiology | Year: 2013

Although malaria remains one of the leading infectious diseases in the world, the decline in malaria transmission in some area makes it possible to consider elimination of the disease. As countries approach elimination, malaria diagnosis needs to change from diagnosing ill patients to actively detecting infections in all carriers, including asymptomatic and low-parasite-load patients. However, few of the current diagnostic methods have both the throughput and the sensitivity required. We adopted a sandwich RNA hybridization assay to detect genus Plasmodium 18S rRNA directly from whole-blood samples from Plasmodium falciparum and Plasmodium vivax patients without RNA isolation. We tested the assay with 202 febrile patients from areas where malaria is endemic, using 20 μl of each blood sample in a 96-well plate format with a 2-day enzyme-linked immunosorbent assay (ELISA)-like work flow. The results were compared with diagnoses obtained using microscopy, a rapid diagnostic test (RDT), and genus-specific real-time PCR. Our assay identified all 66 positive samples diagnosed by microscopy, including 49 poorly stored samples that underwent multiple freeze-thaw cycles due to resource limitation. The assay uncovered three false-negative samples by microscopy and four false-negative samples by RDT and agreed completely with real-time PCR diagnosis. There was no negative sample by our assay that would show a positive result when tested with other methods. The detection limit of our assay for P. falciparum was 0.04 parasite/μl. The assay's simple work flow, high throughput, and sensitivity make it suitable for active malaria screening. Copyright © 2013, American Society for Microbiology. All Rights Reserved.

Hill N.,London School of Hygiene and Tropical Medicine | Zhou H.N.,London School of Hygiene and Tropical Medicine | Zhou H.N.,Yunnan Institute of Parasitic Diseases | Wang P.,Yunnan Institute of Parasitic Diseases | And 5 more authors.
Malaria Journal | Year: 2014

Background: Mosquito coils are the most commonly used household insecticidal product in the world with sales exceeding 50 billion coils, used by two billion people worldwide annually. Despite strong evidence that coils prevent mosquito bites a systematic review concluded that there is no evidence that burning mosquito coils prevents malaria acquisition. Therefore, the current trial was designed to measure and compare prevention of malaria infection by mosquito coils or long-lasting insecticidal net (LLIN) or a combination of the two in Yunnan, China in the Greater Mekong sub-region. Methods. A four-arm single blind household-randomized design was chosen as coils emanate insecticide throughout the household. Households enrolled at baseline were randomly allocated by the lottery method to one of the four intervention arms: (i) nothing, (ii) 0.03% transfluthrin coils alone, (iii) deltamethrin long-lasting insecticide treated nets, (LLINs) alone or (iv) a combination of transfluthrin coils and deltamethrin LLINs. All household members were recruited to the study, with only those households excluded with pregnant or breastfeeding mothers, members with chest complaints or allergies or members that regularly slept away from home. The main outcome of interest was Plasmodium falciparum malaria prevalence detected by rapid diagnostic tests (RDTs) during six repeated monthly cross-sectional surveys. The secondary outcome of interest was the effect on Plasmodium vivax prevalence detected in the same way. Results: A total of 2,052 households were recruited into the study, comprising 7,341 individuals The odds ratios of testing positive by RDT with P. falciparum or P. vivax were >75% lower for all intervention arms compared with the control arm. Coils alone provided 77% protection (95% CI: 50%-89%), LLINs provided 91% protection (95% CI: 72%-97%) and the combination of coils and LLINs provided 94% protection (95% CI: 77%-99%) against P. falciparum compared with the control arm. There was no statistically significant difference between the protective efficacies of the different interventions. Conclusions: This is the first robust clinical evaluation of transfluthrin mosquito coils as a means to reduce malaria and the high degree of infection prevented would indicate they represent a potentially highly effective tool, which could be integrated into larger vector control programmes. Trial registration. Identifier: NCT00442442, March 2007. © 2014 Hill et al.; licensee BioMed Central Ltd.

Xu J.-W.,Yunnan Institute of Parasitic Diseases | Liu H.,Yunnan Institute of Parasitic Diseases | Zhang Y.,Fourth Hospital of Baotou Municipality | Guo X.-R.,Centers for Disease Control and Prevention | Wang J.-Z.,Centers for Disease Control and Prevention
American Journal of Tropical Medicine and Hygiene | Year: 2015

A retrospective case-control study was conducted to identify risk factors for border malaria in a malaria elimination setting of Yunnan Province, China. The study comprised 214 cases and 428 controls. The controls were individually matched to the cases on the basis of residence, age, and gender. In addition, statistical associations are based on matched analyses. The frequencies of imported, male, adult, and vivax malaria cases were respectively 201 (93.9%), 194 (90.7%), 210 (98.1%), and 176 (82.2%). Overnight stay in Myanmar within the prior month was independently associated with malaria infection (odds ratio [OR] 159.5, 95% confidence interval [CI] 75.1-338.9). In particular, stays in lowland and foothill (OR 5.5, 95%CI 2.5-11.8) or mid-hill (OR 42.8, 95% CI 5.1-319.8) areas, or near streamlets (OR 15.3, 95% CI 4.3-55.2) or paddy field or pools (OR10.1, 95% CI 4.4-55.8) were found to be independently associated with malaria. Neither forest exposure nor use of vector control measures was associated with malaria. In conclusion, travel to lowland and foothill or mid-hill hyperendemic areas, especially along the waterside in Myanmar, was found to be the highest risk factor for malaria. In considering the limitations of the study, further investigations are needed to identify the major determinants of malaria risk and develop new strategies for malaria elimination on China-Myanmar border. Copyright © 2015 by The American Society of Tropical Medicine and Hygiene.

Bi Y.,Queensland University of Technology | Bi Y.,Centers for Disease Control and Prevention | Hu W.,University of Queensland | Yang H.,Yunnan Institute of Parasitic Diseases | And 4 more authors.
American Journal of Tropical Medicine and Hygiene | Year: 2013

Malaria has been a heavy social and health burden in the remote and poor areas in southern China. Analyses of malaria epidemic patterns can uncover important features of malaria transmission. This study identified spatial clusters, seasonal patterns, and geographic variations of malaria deaths at a county level in Yunnan, China, during 1991-2010. A discrete Poisson model was used to identify purely spatial clusters of malaria deaths. Logistic regression analysis was performed to detect changes in geographic patterns. The results show that malaria mortality had declined in Yunnan over the study period and the most likely spatial clusters (relative risk [RR] = 23.03-32.06, P < 0.001) of malaria deaths were identified in western Yunnan along the China-Myanmar border. The highest risk of malaria deaths occurred in autumn (RR = 58.91, P < 0.001) and summer (RR = 31.91, P < 0.001). The results suggested that the geographic distribution of malaria deaths was significantly changed with longitude, which indicated there was decreased mortality of malaria in eastern areas over the last two decades, although there was no significant change in latitude during the same period. Public health interventions should target populations in western Yunnan along border areas, especially focusing on floating populations crossing international borders. Copyright © 2013 by The American Society of Tropical Medicine and Hygiene.

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