INTRODUCTION

Effective mosquito control is pivotal in the epidemiology of vector-borne diseases, but no successful preventive measures have been recorded for dengue vector control. Hence, possible alternatives to chemical larvicides have been explored, including plant alcoholic extracts. This study determined the larvicidal efficacy of Annona squamosa ethanolic leaf extracts against third instar larvae of Aedes aegypti.

METHODS

Three replicates of varying concentrations of Annona squamosa ethanolic extract (i.e., 10%, 40%, and 70%) versus positive (Novaluron) and negative controls (tap water) were used to determine larval mortality.

RESULTS

Greatest larval mortality was noted using the 70% concentration (i.e., 24% versus the observed values of 20% and 8%, respectively for the 40% and 10% ethanolic concentrations). Relative to the controls, the mean differences in the mortality rates of the Aedes aegypti larvae across the leaf ethanolic concentrations were statistically significant (i.e., p-value < 0.05). There was increasing trend in larval mortality over time, but 50% lethal dose was not achieved. In conclusion, the different Annona squamosa ethanolic leaf extracts could be used as alternative botanical larvicides against Aedes species.

Plants ; Animals ; Epidemiology ; Mosquito Control

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

As the last part of a program to survey the extent of malaria transmission in the Papua New Guinea highlands, a series of rapid malaria surveys were conducted in 2003-2004 and 2005 in different parts of Southern Highlands Province. Malaria was found to be highly endemic in Lake Kutubu (prevalence rate (PR): 17-33%), moderate to highly endemic in Erave (PR: 10-31%) and moderately endemic in low-lying parts (< 1500 m) of Poroma and Kagua (PR: 12-17%), but was rare or absent elsewhere. A reported malaria epidemic prior to the 2004 surveys could be confirmed for the Poroma (PR: 26%) but not for the lower Kagua area. In Kutubu/Erave Plasmodium falciparum was the most common cause of infection (42%), followed by P. vivax (39%) and P. malariae (16%). In other areas most infections were due to P. vivax (63%). Most infections were of low density (72% < 500/ microl) and not associated with febrile illness. Overall, malaria was only a significant source of febrile illness when prevalence rates rose above 10%, or in epidemics. However, concurrent parasitaemia led to a significant reduction in haemoglobin (Hb) level (1.2 g/dl, CI95: [1.1-1.4.], p < 0.001) and population mean Hb levels were strongly correlated with overall prevalence of malarial infections (r = -0.79, p < 0.001). Based on the survey results, areas of different malaria epidemiology are delineated and options for control in each area are discussed.
Adolescent ; Adult ; Antimalarials/therapeutic use ; Child ; Child, Preschool ; Endemic Diseases ; *Epidemics ; Female ; Geography, Medical ; Humans ; Malaria/drug therapy/*epidemiology/prevention & control ; Malaria, Falciparum/drug therapy/epidemiology/prevention & control ; Malaria, Vivax/drug therapy/epidemiology/prevention & control ; Male ; Mosquito Nets/utilization ; Papua New Guinea/epidemiology ; Prevalence ; Young Adult

INTRODUCTIONThe aim of this study was to compare the knowledge and practices of household mosquito-breeding control measures between a dengue hotspot (HS) and a non-hotspot (NHS).

MATERIALS AND METHODSEight hundred households were randomly sampled from HS and NHS areas, and an National Environment Agency (NEA) questionnaire was administered to heads of the households. Interviewers were blinded to the dengue status of households. We included subjects aged above 16 years, who were communicative and currently living in the household. Chi-square test was used to compare proportions and multiple logistic regression was used to adjust for socio-demographic differences between both areas.

RESULTSThe overall response rate was 59.0% (n = 472). There were significant differences in gender, educational level, employment status and housing type between HS and NHS (all P <0.05). NHS residents were less knowledgeable in 6 out of 8 NEA-recommended anti-mosquito breeding actions: changing water in vase/bowls [AOR (adjusted OR), 0.20; CI, 0.08-0.47; P <0.01], adding sand granular insecticide to water [AOR, 0.49; CI, 0.31-0.71; P <0.01], turning over pails when not in use [AOR, 0.39; CI, 0.17-0.89; P = 0.02], removing flower pot/plates [AOR, 0.35; CI, 0.18-0.67; P <0.01], removing water in flower pot/plates [AOR, 0.36; CI, 0.17-0.75; P <0.01] and putting insecticide in roof gutters [AOR 0.36; CI, 0.13-0.98; P = 0.04]. Hotspot residents reported better practice of only 2 out of 8 NEA-recommended mosquito-breeding control measures: changing water in vases or bowls on alternate days [AOR, 2.74; CI, 1.51-4.96; P <0.01] and removing water from flower pot plates on alternate days [AOR, 1.95; CI, 1.01-3.77; P = 0.05].

CONCLUSIONMore HS residents were knowledgeable and reported practicing mosquito-breeding control measures compared to NHS residents. However, a knowledge-practice gap still existed.

Adult ; Cross-Sectional Studies ; Dengue ; epidemiology ; prevention & control ; Female ; Health Knowledge, Attitudes, Practice ; Housing ; Humans ; Male ; Mosquito Control ; methods ; Singapore ; epidemiology

INTRODUCTIONTo determine the seroepidemiology of dengue virus infection in a representative sample of the adult resident population aged 18 years old to 74 years old in Singapore and to estimate the proportion of asymptomatic dengue infection during the 2004 epidemic.

MATERIALS AND METHODSThe study was based on 4152 stored blood samples collected between September and December 2004 from participants aged 18 years old to 74 years old during the 2004 National Health Survey. Sera were tested for IgG and IgM antibodies using a commercial test kit (PanBio Capture/Indirect ELISA).

RESULTSOf the study population, 59.0% and 2.6% tested positive for dengue IgG (past infection) and IgM/high-titre IgG (recent infection), respectively. Only 17.2% of young adults aged 18 years old to 24 years old were dengue IgG positive. Multivariate analyses showed that older age, Indian ethnicity and male gender were significantly associated with past infection, whereas only age was significantly associated with recent dengue infection. Based on the dengue cases notified during the period of survey, it was estimated that for every 23 individuals recently infected with dengue, only 1 was reported to the health authority as a clinical case.

CONCLUSIONThe Singapore population is highly susceptible to dengue epidemics despite its aggressive Aedes prevention and control programme. The finding of a high proportion of unreported cases due to asymptomatic and subclinical infection poses a challenge for dengue control.

Adolescent ; Adult ; Aedes ; Aged ; Animals ; Confidence Intervals ; Cross-Sectional Studies ; Dengue ; epidemiology ; transmission ; Dengue Virus ; Disease Outbreaks ; Female ; Health Surveys ; Humans ; Immunoglobulin G ; Immunoglobulin M ; Logistic Models ; Male ; Middle Aged ; Mosquito Control ; Multivariate Analysis ; Odds Ratio ; Population Surveillance ; Risk Factors ; Seroepidemiologic Studies ; Singapore ; epidemiology ; Young Adult

INTRODUCTIONWe investigated the 2005 outbreak of dengue fever (DF)/dengue haemorrhagic fever (DHF) to determine its epidemiological, virological and entomological features to further understand the unprecedented resurgence.

MATERIALS AND METHODSAll physician-diagnosed, laboratory-confirmed cases of DF/DHF notified to the Ministry of Health, Singapore during the outbreak as well as entomological and virological data were analysed retrospectively.

RESULTSA total of 14,006 cases of DF/DHF comprising 13,625 cases of DF and 381 cases of DHF, including 27 deaths were reported, giving an incidence rate of 322.6 per 100,000 and a case-fatality rate of 0.19%. The median age of the cases and deaths were 32 and 59.5 years, respectively. The incidence rate of those living in compound houses was more than twice that of residents living in public and private apartments. The distribution of DF/DHF cases was more closely associated with Aedes aegypti compared to Aedes albopictus breeding sites and the overall Aedes premises index was 1.15% (2.28% in compound houses and 0.33% to 0.8% in public and private apartments). The predominant dengue serotype was DEN-1. A significant correlation between weekly mean temperature and cases was noted. The correlation was strongest when the increase in temperature preceded rise in cases by a period of 18 weeks.

CONCLUSIONThe resurgence occurred in a highly densely populated city-state in the presence of low Aedes mosquito population. Factors contributing to this resurgence included lower herd immunity and change in dominant dengue serotype from DEN-2 to DEN-1. There was no evidence from gene sequencing of the dengue viruses that the epidemic was precipitated by the introduction of a new virulent strain. The current epidemiological situation is highly conducive to periodic dengue recurrences. A high degree of vigilance and active community participation in source reduction should be maintained.

Adult ; Aedes ; Animals ; Dengue ; epidemiology ; prevention & control ; transmission ; Dengue Virus ; immunology ; isolation & purification ; pathogenicity ; Disease Outbreaks ; Female ; Humans ; Immunity, Herd ; Incidence ; Insect Vectors ; Male ; Middle Aged ; Mosquito Control ; Primary Prevention ; methods ; Public Health ; Retrospective Studies ; Risk Factors ; Serotyping ; Singapore ; epidemiology

The status of Dirofilaria immitis infection was assessed in pet dogs of Busan, Korea, and chemoprophylactic effects of microfilaricidal medication were evaluated. A total of 294 pet dogs older than 6 mo were examined, 217 of which had been maintained indoors, and 77 had been kept outdoors. The Snap(R) kit and direct microscopic examinations of the peripheral blood were used. The mean overall parasite positive rates were 10.2% and 6.5%, respectively. Outdoor dogs evidenced adult worm infection rate of 31.2% and microfilaria infection rate of 18.2%. The indoor dogs, however, evidenced adult worm infection rate of 2.8% and microfilaria infection rate of 2.3%. The prevalence in males was more than 2 times that of females. The changing pattern of infection rates by age evidenced a gradual increase, from 2- to 6-year-old dogs, after which, a decrease in infection rates was noted. With regard to chemoprophylaxis, the infection rates of complete and incomplete chemoprophylaxis groups were found to be 2-3 times lower than that of the non-chemoprophylaxis group. The results of the present study indicate that the risk of exposure to D. immitis in pet dogs is quite high, particularly in male outdoor dogs, and chemoprophylactic measures were quite effective.
Animals ; Chemoprevention ; Dirofilaria immitis/growth & development/*isolation & purification ; Dirofilariasis/blood/*epidemiology/parasitology/prevention & control ; Dog Diseases/blood/*epidemiology/parasitology/prevention & control ; Dogs ; Female ; Heart/parasitology ; Korea/epidemiology ; Male ; Mosquito Control ; Prevalence

Olyset net sunk with 2% permethrin was used in Hai Duong, Hai Phong, Thai Binh. The rate of density index and house index were decreased from 0.23 and 23.3 to zero and persisted by 9 months. Breteau index and larve-house index was also decresed from 8.3 and 6.7 to zero. Olyset net showed its effect on Aedes aegypti and in various mosquitos and insects
Dengue Hemorrhagic Fever ; Mosquito Control ; Disease ; epidemiology

Since the national malaria eradication service (NMES) was implemented in 1959, extensive malariometric survey were conducted throughout the country. A total of 73,859 malaria cases of Plasmodium vivax were confirmed out of 268,259 blood smears through passive and active case detection (PCD and ACD) in 1960~1969 including chloroquine/ pyrimethamine combined tablets for the presumptive treatment of all of fever cases. The majority of the positive cases occurred in Gyeongsang buk-do, revealing 62,859 cases as of 85.2%, followed by Gyeonggi-do 5,844 cases (7.9%), Chungcheong buk-do 3,458 cases (4.7%), Gangwon-do 812 cases (1.1%), and 29 cases developed in Jeju-do. ACD was more sensitive and advantageous for detecting the malaria cases over PCD in the pilot study area. The high endemic area was located in the north Gyeongsang buk-do and north east Gyeonggi-do. The malaria incidence was high in the age group under 14 years in malaria foci, and that was low in non-malarious area. High parous rate (77.7%) and survival rate (91.4%) of the vector mosquitoes were shown in malaria foci, which were hilly or mountainous area. On the other hand, low parous rate (50.6%) and survival rate (42.7%) were found in non-malarious area, the rice field of south western part of the country even in abundance of vector mosquitoes. NMES had contributed the control of the malaria by carring out the residual DDT focal spray, mass drug administration, radical treatment of the positive cases, and mass blood survey in the heavy malarious area. Since then malaria disappeared rapidly, and no indigenous case was reported after 1984. In order to ascertain whether this country was malaria-free or not, mass blood survey was carried out for the juveniles, adolescents and adults in Yeongju-gun Gyeongsangbuk-do in 1986 where the highest incidence of malaria was recorded during the 1960s. The result showed no positive case at all. However vivax malaria reemerged, and made a dramatic resurgence since 1993 in the demilitarized zone (DMZ) bordering North Korea, and expanded toward eastern and southern part of the country year after year, totaling 14,089 cases including U.S. army by the end of 2000 in spite of the strong activities of antimalaria in the Republic of Korea. So vector control including the encouragement of the livestock farming in the malaria endemic area must be more sensitive and effective measure to reduce the risk of malaria transmission by the eliminating the dangerous age of mosquitoes in the points of characteristics of the Korean strain of parasites such as the mild symptoms, long-term incubation period and asymptomatic parasitaemia. Focal application of thermal fogging and mist spray of insecticides would be certainly effective in preventing the vector mosquitoes from infecting the gametocytes of malaria for the first peak of multi malaria cases in the early season of the year. All of the civilians who are in the high risk area for malaria should be forced to sleep under the permethrin impregnated mosquito nets. All of the soldiers near the DMZ are strongly recommended to take the combined tablets of chloroquine/ pyrimethamine instead of the single base of chloroquine at present to prevent the action of source of infection of the reservoirs and the completion of the sporogonic stages of the vector mosquitoes because the vector control activities are not allowed in the DMZ. The experts of entomologists and malariologist of the South and North Korea should discuss the antimalaria programme to eradicate the malaria from the Korean peninsular near future.
Adolescent ; Adult ; Chloroquine ; Culicidae ; DDT ; Democratic People's Republic of Korea ; Epidemiology ; Fever ; Gangwon-do ; Gyeonggi-do ; Gyeongsangbuk-do ; Hand ; Humans ; Incidence ; Insecticides ; Jeju-do ; Korea* ; Livestock ; Malaria* ; Malaria, Vivax ; Military Personnel ; Mosquito Nets ; Parasites ; Permethrin ; Pilot Projects ; Plasmodium vivax ; Pyrimethamine ; Republic of Korea ; Seasons ; Survival Rate ; Tablets ; Weather

In order to determine the seasonal prevalence and population density of vector mosquitoes in Kyungpook province, a survey based on average number of female mosquito per trap-night, were carried out during the period from May to November in 1984. Among the 34,571 mosquitoes collected in Kyungsan county in animal shelters and human dwellings by light traps, approximately 45.0 % were Culex tritaeniorhynchus, 34. 0 % per cent Culex pipiens pallens, and 19.0 per cent Anopheles sinensis. By comparison, distribution of mosquito species in Ankang town, in which Japanese encephalitis had been reported in the past, were quite different and A. sinensis was the most abundant species, being constituted in 75.8 per cent, followed by C. tritaeniorhynchus(23. 2 percent), and C. pipiens pallens(0. 6 per cent). In the general patten of seasonal prevalence, C. tritaeniorhynchus first appeared in mid-June, and trapped in large numbers during the periods from mid-August to early September, showing a simple sharply pointed one-peaked curve, while C. pipiens pallens was found to be active through almost the entire season showing irregular curves with several peaks. The trend of seasonal distribution of A. sinensis was similar to that of C. tritaeniorhynchus, but the earliest dates of appearance and disappearance different form that of C. tritaeniorhynchus. The results of hourly catches of mosquitoes by human baited traps have clearly shown the differences in the biting rhythm among the vector mosquitoes of this province, such as the facts that C. tritaeniorhynchus and A. sinensis are rather constantly active all through a night with more or less inconspicuous peaks twice a night, while C. pipiens pallens exhibits an irregular curve, and the numbers of A. vexans nipponii, C. vagans and Armigeres subalbatus are very small and are not sufficient for estimating the biting rhythm. Four genera and fourteen species of larval mosquitoes collected from eighteen kinds of habitats which classified according to the categories followed by Bates(1949). The main breeding sites contributing to peak C. tritaeniorhynchus adult densities in this surveyed areas were evidently ricefields, ground pools, puddles and swamps and marshes, etc. Summarizing the results, this study indicated that the highest population density of C. tritaeniorhynchus was encountered in late August and early September, showing simple sharply pointed one-peaked curve.
parasitology-arthropoda ; mosquito-epidemiology ; Culex tritaeniorhynchus ; Culex pipiens pallens ; Anopheles sinensis