Three anopheline mosquitoes in Korea were studied for their abilities as vectors for Plasmodium vivax. The female mosquitoes of Anopheles lesteri, An. pullus and An. sinensis were allowed to suck malaria patient blood until fully fed, and they were then bred for 2 weeks to develop from malaria parasites to sporozoites. The result from the above confirmed the sporozoites in one An. lesteri of one individual and five An. sinensis of six individuals. We also reconfirmed that An. sinensis was the main vector to transmit malaria and An. lesteri as well as An. sinensis were able to carry Korean malaria parasites. Therefore, we propose that diversified study is needed to manage malaria projects.
Adult ; Animals ; Culicidae/*parasitology/*physiology ; Female ; Humans ; *Insect Vectors ; Korea ; Malaria/parasitology/transmission ; Male ; *Plasmodium vivax

Field trials evaluating selected commercially available mosquito traps variously baited with light, carbon dioxide, and/or octenol were conducted from 18 - 27 September 2000 in a malarious area near Paekyeon-ri (Tongil-Chon) and Camp Greaves in Paju County, Kyonggi Province, Republic of Korea. The host-seeking activity for common mosquito species, including the primary vector of Japanese encephalitis, Culex tritaeniorhynchus Giles, was determined using hourly aspirator collections from a human and propane lantern-baited Shannon trap during hours when temperatures exceeded 15oC. The total number of mosquitoes and number of each species captured during the test was compared using a block design. Significant differences were observed for the total number of mosquitoes collected, such that, the Mosquito MagnetTM with octenol > Shannon trap > ABC light trap with light and dry ice > Miniature Black Light trap (manufactured by John W. Hock) >; or = New Jersey Trap > ABC light trap with light only. Significant differences in numbers collected among traps were noted for several species including: Aedes vexans (Meigen), Anopheles lesteri Baisas and Hu, An. sinensis Weidemann, An. sineroides Yamada, An. yatsushiroensis Miyazaki, Culex pipiens L., Cx. orientalis Edwards and Cx. tritaeniorhynchus. Host-seeking activity for most common species showed a similar bimodal pattern. Results from these field trap evaluations can significantly enhance current vector and disease surveillance efforts especially for the primary vector of Japanese encephalitis, Cx.tritaeniorhynchus.
Animals ; *Appetitive Behavior ; Culicidae/*physiology ; Encephalitis, Japanese ; Humans ; Insect Vectors ; Korea ; Light ; Mosquito Control/*instrumentation/methods ; Seasons

OBJECTIVETo explore the associations between the monthly number of dengue fever(DF) cases and possible risk factors in Guangzhou, a subtropical city of China.

METHODSThe monthly number of DF cases, Breteau Index (BI), and meteorological measures during 2006-2014 recorded in Guangzhou, China, were assessed. A negative binomial regression model was used to evaluate the relationships between BI, meteorological factors, and the monthly number of DF cases.

RESULTSA total of 39,697 DF cases were detected in Guangzhou during the study period. DF incidence presented an obvious seasonal pattern, with most cases occurring from June to November. The current month's BI, average temperature (Tave), previous month's minimum temperature (Tmin), and Tave were positively associated with DF incidence. A threshold of 18.25 °C was found in the relationship between the current month's Tmin and DF incidence.

CONCLUSIONMosquito density, Tave, and Tmin play a critical role in DF transmission in Guangzhou. These findings could be useful in the development of a DF early warning system and assist in effective control and prevention strategies in the DF epidemic.

Animals ; China ; epidemiology ; Culicidae ; physiology ; Dengue ; epidemiology ; Epidemics ; statistics & numerical data ; Humans ; Population Density ; Time Factors ; Weather

This study aims to investigate the distribution patterns of mosquito-borne viruses in Menghai County, Xishuangbanna Prefecture, Yunnan Province, China and to provide evidence for the prevention and control of mosquito-borne diseases. Mosquito samples were collected using mosquito lamps. Viruses were isolated from the samples by cell culture, and the isolates were identified by RT-PCR. The genomes of isolates were sequenced for phylogenetic analysis. In July 2012, a total of 1468 mosquitoes were captured in Daluo Town of Menghai County; they were divided into 32 pools, including Culex tritaeniorhynchus (28 pools, 1383 mosquitoes), Culex quinquefasciatus (2 pools, 66 mosquitoes), and Anopheles (2 pools, 19 mosquitoes). Golden hamster kidney cells (BHK-21) and Aedes albopictus cells (C6/36) were used for virus isolation. The results showed that C6/36 cells were susceptible to two isolates recovered from Culex tritaeniorhynchus (BNDL1205 and BNDL1227), with marked cytopathic effect (CPE) of cell fusion. By contrast, the two isolates could not cause CPE in BHK-21 cells. RT-PCR was performed for the two isolates using the flavivirus-specific primers FU2/cFD3, and a 800-bp amplicon was obtained from both of them. Phylogenetic analysis showed that the two isolates shared the same evolutionary branch with the Quang Binh virus (QBV) strain VN180, which had been isolated from Vietnam, with nucleotide sequence homologies of 83.4% and 82.9%, respectively. However, there existed relatively large differences in nucleotide sequence between them and other Culex flavivirus strains previously isolated in China and other regions. In light of the similarity between the two isolates and QBV, BNDL1205 and BNDL122 were referred to as Quang Binh-like virus, which were first reported in China.
Animals ; Cell Line ; China ; Cricetinae ; Culicidae ; virology ; Evolution, Molecular ; Insect Viruses ; isolation & purification ; physiology ; Phylogeny ; Sequence Homology

OBJECTIVETo define and evaluate the malaria transmission potential in the Yangtze River, following construction of the Three Gorges Reservoir.

METHODSSix villages, namely, Kaixian, Fengjie, Wanzhou, Fuling, Yubei, and Zigui were selected for investigating the malaria transmission potential in the reservoir. Transmission potential was estimated by mathematical modeling and evaluation of the local malaria situation. Factors that influenced the transmission potential were analyzed using Poisson regression analysis in combination with Grey Systematic Theory (based on evaluation by the Delphi method).

RESULTSIndirect fluorescent antibody data and the incidence of malaria in the local population were consistent with the malaria transmission potential calculated for the area. Multivariate Poisson regression analysis showed a statistically significant association between the riparian zone and the man-biting rate.

CONCLUSIONThe risk of a malaria epidemic can be forecasted using the malaria transmission potential parameters investigated here which was closely correlated with the riparian zone.

Animals ; China ; epidemiology ; Culicidae ; physiology ; Epidemics ; prevention & control ; Housing ; Humans ; Insect Bites and Stings ; Malaria ; epidemiology ; transmission ; Rivers ; Water Resources

It is important to understand the dynamics of malaria vectors in implementing malaria control strategies. Six villages were selected from different sections in the Three Gorges Reservoir for exploring the relationship between the climatic factors and its malaria vector density from 1997 to 2007 using the auto-regressive linear model regression method. The result indicated that both temperature and precipitation were better modeled as quadratic rather than linearly related to the density of Anopheles sinensis.
Animals ; China ; Climate ; Culicidae ; physiology ; Insect Vectors ; physiology ; Lakes ; Linear Models ; Malaria ; parasitology ; transmission ; Models, Biological ; Plasmodium ; physiology ; Population Density ; Population Dynamics ; Rain ; Seasons ; Temperature

OBJECTIVETo evaluate the effect of preventive medicine for residents living around mosquito breeding water during rest period of malaria by delimiting a certain range.

METHODThe study adopted the stratified cluster random sampling method to select subjects from 6 counties in the high epidemic area along and north of the Huai River since March 2007. Then the villages of 6 counties were stratified into five levels according to the case reported in year 2006, and one village was randomly selected from each level, thereby 30 villages were selected in total.300-500 subjects were interviewed in each village, and in total 12 860 subjects were recruited in the study. The five selected villages in each county were allocated to three intervention groups according to the block randomization method. The first intervention group included 9 villages, 4362 people; the second intervention group was consisted of 12 villages, 4471 people; the non-intervention group had 9 villages, 4027 people. The basic information of the subjects were collected by questionnaire to analyze the relation between malaria cases and the distribution of the mosquito breeding water, then accordingly delimited the range for preventive medicine. Group 1 received the delimiting preventive medicine treatment, group 2 received routine medicine treatment, while non-treatment group received no treatment. The morbidity, standardized morbidity, net change of morbidity (the D-value of the standardized morbidity before and after the intervention), age-specified incidence, and the protective rate (PR), effectiveness index (IE) and the capture rate of the delimited method group were then calculated.

RESULTSGroup 1 had 1219 (27.9%) people taking medicine and Group 2 had 219 (4.9%) people. In 2006, before the prevention conducting, the high incidence aging group in the first, second and nonintervention group was separately people aging 50 - 59, 60 - 69 and ≥ 70 years old; whose incidence was 36.22‰ (18/497), 40.11‰ (15/374) and 34.88‰ (9/258) respectively. After the intervention, the high incidence aging groups in the first and second intervention group changed to the population over 70 years old, with incidence at 9.17‰ (3/327) and 22.01‰ (7/318) respectively; while the high incidence aging groups in the nonintervention group changed to people aging between 30-39 years old, with the rate at 24.88‰ (10/402). In 2006, the morbidity of malaria in the first, second intervention group and nonintervention group was separately 18.78‰ (83/4420), 20.27‰ (93/4587) and 14.61‰ (53/3627); while the standardized incidence was separately 18.85‰, 20.72‰ and 14.89‰. In 2007, after the prevention conducting, the morbidity in the three groups was 2.75‰ (12/4362), 11.63‰ (52/4471) and 12.17‰ (49/4027), respectively; while the standardized incidences was 2.81‰, 12.75‰ and 12.35‰, respectively. The net value of changes of morbidity in the three groups was separately 16.04%, 7.97% and 2.54%. The difference in net values of changes of morbidity between intervention group 1 and 2 had statistical significance (χ(2) = 7.74, P < 0.05). Comparing with the nonintervention group, the PR and IE in intervention group 1 was separately 84.2% and 6.31; while the capture rate was 69.2% (9/13).

CONCLUSIONThe delimiting preventive medicine treatment during rest period of malaria was very effective for eliminating the potential infection source of malaria and reducing the morbidity of malaria.

Adolescent ; Adult ; Aged ; Animals ; Child ; Child, Preschool ; China ; epidemiology ; Culicidae ; physiology ; Humans ; Incidence ; Infant ; Infant, Newborn ; Malaria ; drug therapy ; epidemiology ; prevention & control ; Middle Aged ; Water ; parasitology ; Young Adult

OBJECTIVEAssessment of the bacterium L. sphaericus as a dual-action candidate for biological control of mosquito-borne diseases and bioremediation of toxic metals.

METHODSLarvae of the mosquito, C. quinquefasciatus, were first evaluated for metal tolerance and then exposed to 5 ppm cadmium, chromium, arsenic, and lead in assays together with seven strains of L. sphaericus. A probit regression analysis was used to estimate the LC(50) of Cd, Cr, As, and Pb to C. quinquefasciatus. An analysis of covariance and multifactorial ANOVA examined the metal biosorption and larvicidal properties of the seven strains of L. sphaericus.

RESULTSWe found that L. sphaericus adsorbed the toxic metal ions and was toxic against mosquito larvae. The L. sphaericus strain III(3)7 resulted in a larvae mortality of over 80% for all the tested metals. This strain also exhibited the capacity to adsorb 76% of arsenic, 32% of lead, 25% of chromium, and 7% of cadmium.

CONCLUSIONThis study found combined metal adsorption and larval toxicity associated with three strains of L. sphaericus [III(3)7, OT4b.31, and CBAM5]. This suggests that a combination of these strains shows strong dual potential for biological control of mosquitos in heavy metal-contaminated areas and remediate the heavy metal contamination as well.

Animals ; Bacillaceae ; physiology ; Culicidae ; microbiology ; Host-Pathogen Interactions ; Insect Vectors ; Larva ; microbiology ; Metals, Heavy ; metabolism ; toxicity ; Water Pollutants, Chemical ; metabolism ; toxicity

OBJECTIVETo investigate the abundance and seasonal dynamics of mosquitoes, and to detect Japanese encephalitis virus (JEV) in these mosquitoes at the nesting colony of ardeid birds.

METHODSMosquitoes were collected bimonthly from July 2009 to May 2010 by Centers for Disease Control. Light traps and dry ice, as a source of CO2, were employed to attract mosquitoes. Mosquitoes were first identified, pooled into groups of upto 50 mosquitoes by species, and tested for JEV infection by viral isolation and reverse transcriptase polymerase chain reaction.

RESULTSA total of 20 370 mosquitoes comprising 14 species in five genera were collected. The five most abundant mosquito species collected were Culex tritaeniorhynchus (95.46%), Culex vishnui (2.68%), Culex gelidus (0.72%), Anopheles peditaeniatus (0.58%) and Culex quinquefasciatus (0.22%). Mosquito peak densities were observed in July. All of 416 mosquito pools were negative for JEV.

CONCLUSIONSThis study provides new information about mosquito species and status of JEV infection in mosquitoes in Thailand. Further study should be done to continue a close survey for the presence of this virus in the ardeid birds.

Animals ; Bird Diseases ; epidemiology ; virology ; Birds ; Culicidae ; physiology ; virology ; Encephalitis Virus, Japanese ; isolation & purification ; Encephalitis, Japanese ; epidemiology ; veterinary ; virology ; Population Dynamics ; Reverse Transcriptase Polymerase Chain Reaction ; veterinary ; Seasons ; Thailand ; epidemiology ; Virus Cultivation ; veterinary

In Nigeria, malaria causes up to 11% of maternal mortality. Our main aim was to find out the most common mosquito control measures employed by the pregnant women in Lagos and their effects on malaria infection. The study was carried out over a period of 6 months during which trained interviewers administered questionnaires to 400 pregnant women. The prevalence of malaria was 8.4%. There was no significant association between the prevalence of malaria and age, level of education, or occupation of the participants. Pregnant women in the age range 26-30 had the mean parasite density (409.9+/-196.80). Insecticide spray (32.8%), mosquito coil (27.5%), and insecticide-treated nets (ITN) (15.5%) were the major mosquito control measures employed by the participants while the prevalence of infection among them were 2.3%, 6.2%, and 3.2%, respectively (P<0.05). Only 18.3% of the women had taken more than one dose of intermittent preventive treatment (IPT), while another 11.8% had taken a single dose. The infection rate among them was 4.1% and 6.4%, respectively. Malaria prevalence was highest among those who had not received any dose of IPT (10%). This study showed that the use of ITN and IPT among the pregnant women were still unacceptably low. It also showed that the use of insecticide spray which was the most common malaria control measure adopted by the participants was effective despite the fact that it is not a National Malaria Control Policy. We recommend that a sustained integrated mosquito management and public education should be strengthened in Nigeria.
Adolescent ; Adult ; Animals ; *Culicidae/parasitology ; Female ; Health Knowledge, Attitudes, Practice ; Humans ; *Insect Vectors/parasitology ; Insecticides ; Malaria/epidemiology/*prevention & control ; Mosquito Control/*methods ; Nigeria/epidemiology ; Plasmodium/*physiology ; Pregnancy ; Pregnancy Complications, Parasitic/epidemiology/*prevention & control ; Prenatal Care ; Prevalence ; Public Health ; Questionnaires ; Young Adult