Standard WHO Methods Research Articles

Insecticide resistance status and bar-codingof dengue vectors in three districts of Tamil Nadu, India.

Occurrence and distribution of vector population are crucial for entomological study in context of prevention, control and elimination of vector-borne diseases. To update some entomological aspects in three districts of Tamil Nadu state namely Kumbakonam, Nagapattinam and Thriuvarur districts, the study was undertaken. The objective of the study was to understand the prevalence of mosquitoes; to assess insecticide resistance and phylogenetic analysis of dengue vectors [Aedes (Ae.) aegypti and Ae.albopictus]. The immature stages of mosquitoes were collected from different localities by standard WHO methods marking with GPS and mapping was done using ArcGIS 10.4 software for all three districts. Insecticide resistance test was conducted using WHO susceptibility test kits. The F1 generation of female adult mosquitoes of Ae. aegypti and Ae. albopictus were exposed to DDT 4% and Malathion 5% with the control paper of Risella oil and olive oil respectively. Further, genomic DNA of individual mosquito was isolated, and the sequencingwas done through Eurofins, Bangalore, India. The FASTA sequence was analyzed and the phylogenic tree was constructed using the Maximum likelihood method in Molecular Evolutionary Genetics Analysis (MEGA) software (version 10.0). A totally 5307 specimens were collected through expanded survey in all three study areas. The collection yielded 16 species from six genera of mosquitoes. In total collection, the Ae. albopictus was the dominant species in Kumbakonam and Thiruvarur districts and Ae. aegypti was dominant in Nagapattinam district. The predominant breeding sources were discarded tyre with rainwater, plastic cups, coconut shells, aluminum vessels, sliver containers, bottles, grinding stones and earthen pots etc. The study revealed high pupal indices in all three study areas. Insecticide resistance monitoring revealed possible resistance in Ae. aegypti against DDT in all three districts whereas against Malathion, possible resistance was recorded in Kumbakonam and Nagapattinam and in Thiruvarur district, the species was found to be susceptible. Ae. albopictus showed resistance against DDT in all three districts but susceptible to Malathion. The sequences obtained for Dengue vectors showed 99% similar with Genbank. The phylogenetic tree was constructed using COI region sequences. Certainly, observed the different genetic relationship among Ae. aegypti and Ae. albopictus between the study areas. The study confirmed the presence of Ae. aegypti and Ae. albopictus in all three districts. The study further revealed that these vectors are susceptible to Malathion but resistance to DDT. The continue surveillance of dengue vector and monitoring of insecticide resistance will strengthen the control programme for appropriate vector control measurements.

The contribution of individual characteristics of <i>Anas</i> and <i>Aythya</i> individuals to their susceptibility to low‐pathogenic avian influenza viruses in the south of Western Siberia

Aim. Analysis of the influence of species, sex, and age of genus Anas and Aythya individuals on their sensitivity to low pathogenic avian influenza viruses (LPAIV) in the south of Western Siberia. Material and Methods. Infestation of ducks with the influenza virus was determined by cloacal swabs obtained from 5014 individuals of ducks belonging to the genus Anas and Aythya during the autumn migration period in the south of Western Siberia. Isolation of influenza A virus isolates was carried out according to standard WHO methods. The distribution of infected individuals was estimated with ꭓ2. Relative risk (RR) was used to estimate the risk of infection for each individual species. Results. Among the examined ducks, the distribution between species differed between infected and uninfected individuals. The common teal was under greater risk of being infected with the avian influenza virus. In this species, the sex of the individual influenced the probability of infestation both in young individuals and the whole age spectrum. Conclusions. Individual characteristics of wild dabbling and diving ducks (species, sex, age) affect their infestation with low‐pathogenic avian influenza virus during the autumn migration period in the south of Western Siberia.

Insecticide susceptibility status of malaria vectors in Himachal Pradesh, India.

The state of Himachal Pradesh is one of the hilly forested states of India. Warming of climate has been evidenced in the state due to the ongoing climate change which may cause the upsurge/introduction of mosquito-borne diseases. To curb disease transmission, an effective vector control strategy will be required. Insecticide susceptibility status of available malaria vectors was determined using the standard WHO method in six districts Kangra, Una, Mandi, Bilaspur, Solan and Mandi of the state. An. culicifacies and An. fluviatilis were tested against DDT (4%), malathion (5%) and deltamethrin (0.05%) using WHO insecticide susceptibility kits. Overall, An. culicifacies was found resistant to DDT in all the six districts, susceptible to malathion in all districts except Bilaspur and Solan where it showed possible resistance. It was susceptible to deltamethrin in all the study districts. An. fluviatilis was resistant to DDT and susceptible to malathion and deltamethrin in Kangra and Una districts. At present, indoor residual spraying (IRS) is not being undertaken in Himachal Pradesh. However, with the information generated through the present study, the state government can plan evidence-based IRS at least for focal spray in limited foci reporting malaria incidence.

Larvicidal Effect of Vitex ovata Thunb. (Lamiales: Lamiaceae) Leaf Extract towards Aedes (Stegomyia) aegypti (Linnaeus, 1762) (Diptera: Culicidae)

According to the WHO there are more than 700,000 deaths every year involving vector-borne diseases such as malaria, dengue, Chagas disease, yellow fever and Japanese encephalitis. Aedes aegypti, the principal vector of the dengue virus, is of great concern in various parts of the world, especially in tropical and subtropical countries. Vector control through insecticide application is one of the best ways to control the disease’s transmission. Thus, insecticide resistance in Ae. aegypti poses a significant threat to public health worldwide. The use of plant natural product-based insecticides that are less harmful to the environment, and without known resistance development, constitutes an alternative to chemical insecticides. Given this, a methanolic extract from Vitex ovata plants was prepared and tested for its larvicidal effect against Ae. aegypti. A susceptibility test on Ae. aegypti larvae was conducted using the standard WHO method. Results showed that the methanolic extract of V. ovata had larvicidal activity against Ae. aegypti with LC50 values of 2114 mg/L, and achieved 84% mortality with the highest concentration at 10,000 mg/L. This study showed that the crude extract of V. ovata bioactive molecules could be potentially developed as biolarvicides for Aedes mosquito vector control. This study recommends future research on using different solvents in the isolation of active ingredients from V. ovata, identification of phytochemicals with larvicidal properties, a toxicity study and lastly, an evaluation of the effectiveness of controlling Aedes in small-scale field trials for environmentally safe botanical insecticide intervention.

Validation of a redesigned pan-poliovirus assay and real-time PCR platforms for the global poliovirus laboratory network.

Surveillance and detection of polioviruses (PV) remain crucial to monitoring eradication progress. Intratypic differentiation (ITD) using the real-time RT-PCR kit is key to the surveillance workflow, where viruses are screened after cell culture isolation before a subset are verified by sequencing. The ITD kit is a series of real-time RT-PCR assays that screens cytopathic effect (CPE)-positive cell cultures using the standard WHO method for virus isolation. Because ITD screening is a critical procedure in the poliovirus identification workflow, validation of performance of real-time PCR platforms is a core requirement for the detection of poliovirus using the ITD kit. In addition, the continual update and improvement of the ITD assays to simplify interpretation in all platforms is necessary to ensure that all real-time machines are capable of detecting positive real-time signals. Four platforms (ABI7500 real-time systems, Bio-Rad CFX96, Stratagene MX3000P, and the Qiagen Rotor-Gene Q) were validated with the ITD kit and a redesigned poliovirus probe. The poliovirus probe in the real-time RT-PCR pan-poliovirus (PanPV) assay was re-designed with a double-quencher (Zen™) to reduce background fluorescence and potential false negatives. The updated PanPV probe was evaluated with a panel consisting of 184 polioviruses and non-polio enteroviruses. To further validate the updated PanPV probe, the new assay was pilot tested in five Global Polio Laboratory Network (GPLN) laboratories (Madagascar, India, Philippines, Pakistan, and Democratic Republic of Congo). The updated PanPV probe performance was shown to reduce background fluorescence and decrease the number of false positives compared to the standard PanPV probe.

Efficacy of Extractions of Iranian Native Plants against Main Malaria Vector, Anopheles stephensi in Iran for Making Appropriate Formulation for Disease Control

Malaria is the main vector-borne disease worldwide. There are several reports of insecticide resistant in malaria vectors worldwide due to using different insecticides. The aim of this study was to evaluate different native plant extortions against main malaria vector, Anopheles stephensi in Iran for choosing the appropriate plant for formulation and use for vector control. The larvae of An. stephensi were reared in insectary, extraction of plants were carried out at department of Pharmacology. The standard WHO method for biological tests was used for calculation of LC50 and LC90. Probit regration lines were plotted for calculation of LC50 and LC90. In this study several plants including: Mentha spicata, Cymbopogon olivieri, Azadirachta indica, Melia azedarach, Lagetes minuta, Calotropis procera, Eucalyptus camaldulensis, Cupressus arizonica, Thymus vulgaris, Lawsonia inermis, Cedrus deodara, Cionura erecta, Bunium persicum, Carum carvi, Artemisia dracunculus, Rosmarinus officinalis were used. Results showed that Mentha spicata and Eucalyptus camaldulensis, had the lowest and highest LC50 respectively. Results indicated that Mentha spicata and Eucalyptus camaldulensis, had the lowest and highest LC50 respectively. Several other plant extract also showed significant mortality. The formulation of these plants should be prepared and evaluate at the field condition against malaria vectors.

Body fat and lipid parameters of management assistants in a rural area in Sri Lanka

Background Fat in certain body compartments has a significant contribution to dyslipidemia. Objective The objective was to determine the fat distribution in various body compartments among management assistants (clerks: sedentary occupational group), from the Anuradhapura Municipal Council area, Sri Lanka and to estimate their lipid profiles for any correlation with fat distribution. Methods In this descriptive cross-sectional study [n=78; males=15(mean age=38(11) years); females=63 (mean age=39(9) years)], weight, height, waist and hip circumferences were measured using standard WHO methods. Body fat was measured using 8 electrode bio impedance analyzer system (HBF375 Karada Scan, Japan). Lipid profile was estimated using colorimetric assay kit methods. Results According to the BMI, 57% of females were obese and 13% were overweight, and 67% of males were obese and 20% were overweight. Abdominal obesity [WC>90cm males; >80cm females] was present in 73% of males and 81% of females. Based on total BF% (males>25%; females>35%-obese), 73% males and 65% females were obese. Twenty nine percent of females and 73% of males had a high visceral fat percentage (>10%). Among the females, 68%, 17%, 92% and among males, 73%, 27%, 80% had hypercholesterolaemia, hypertriglyceridemia and high LDL levels, respectively. Low HDL levels were observed in 47% of males and 68% of females. Conicity index (CI) and body adiposity index (BAI) were at high risk level in 93% of males and 75% of females and 27% of males and 56% of females, respectively. Conclusion The prevalence of overweight and obesity was high among the individuals of the study group and a majority were unaware that they were dyslipidemic.

Status of insecticide resistance in An. culicifacies in Gadchiroli (Maharashtra) India

An. culicifacies is the major vector of malaria in tribal community and tribal dominated areas in India. Development of resistance to insecticides is the major challenge to curb the transmission. Gadchiroli (Maharashtra) is a tribal district in central India where incidence of malaria increased from 2012 to 2015 despite indoor space spray with synthetic pyrethroids. To determine the susceptibility status of An. culicifacies against commonly used insecticides in public health program in Gadchiroli. standard WHO method and test kit were used. The insecticide impregnated papers were procured from vector control unit Malaysia. An. culicifacies found resistance to three major groups of pesticides i.e. organochlorine (DDT 4%), organophosphorous (Malathion 5%) and pyrethroids (Cyfluthrin 0.15%, Deltametherin 0.05% and Lambdacyhalothrin 0.05%). The susceptibility status in Permethrin 0.75% needs further confirmation. Development of resistance to different insecticides of varied groups is an adverse finding for the elimination of malaria, explaining the recent increase in malaria incidence in Gadchiroli. The phenomenon further needs to be studied in different locations and the susceptibility needs to test against other insecticides. The findings may have significant implications to the choice of insecticides in the malaria control program in tribal areas.

Detoxification enzymes activities in deltamethrin and bendiocarb resistant and susceptible malarial vectors (<i>Anopheles gambiae</i>) breeding in Bichi agricultural and residential sites, Kano state, Nigeria

Insecticide resistance is an important impediment to malaria control effort. Knowledge of insecticides resistance status is an essential tools to governmental, nongovernmental and insecticides producing industries whose daily challenge is minimization of malaria burden across the globe. Larvae of Anopheles gambiae collected from residential and agricultural areas of Bichi LGA, Kano States, North west Nigeria were reared to adults. Resistance and susceptibility status in the adults mosquitoes were studied by WHO paper bioassay impregnated with diagnostic dose of Deltamethrin and Bendiocarb. The insecticides resistance and susceptible adult mosquitoes of Bichi; residential areas (BR) and agricultural areas (BA) were respectively designated as BRr, BRs, BAr and BAs. Specific activities of insecticides detoxifying enzymes glutathione S transferase (GST), esterase and monooxygenase in resistant and susceptible vectors were measured using standard WHO methods. Although the levels of resistance varied with the insecticides and breeding site, high resistance status of malaria vectors to deltamethrin was recorded in both study sites (> 80% mortality) and incipient resistance (Tolerance) to bendiocarb (>97% mortality) based on WHO results interpretation. Significantly elevated (P<0.05) activities of GST, esterase and monooxygenase were recorded in deltamethrin and bendiocarb resistant strains compared to susceptible species in both BA and BR. The finding of the study established high resistance status to deltamethrin and incipient resistance to bendiocarb in all the study sites which could be linked to indiscriminate use of insecticides in residential sites against malarial vector and other flying insects and agrochemicals for pest control in the agricultural sites. Based on this finding, it may be concluded that insecticides resistance to malaria vector exists in both residential and agricultural areas and measures should be taken to curtail it. Keywords : insecticides (deltamethrin and bendiocarb) resistance, Bioassay, Malarial vector, detoxification enzymes.

Insecticide resistance testing in malaria vectors in Tanzania: Challenges in mosquito sampling and rearing under field conditions

Background: The National Institute for Medical Research, Amani centre, in collaboration with National Malaria Control Programme, has been conducting annual insecticide resistance surveillance since 1999, aimed at early detection of resistance to insecticides used for malaria control in Tanzania. The Standard WHO method for larvae collection and rearing were used but challenges and limitations were encountered. For example rearing the larvae and adult mosquitoes using the Standard WHO method experienced 100% mortality for larvae; and adults in three days. The researchers therefore made modifications to the Standard WHO method to create suitable tools for the field environment. Methods: A ladle was created from an empty water bottle in which an oval hole longitudinally cut halfway from the bottom. Instead of using TetraMin as mosquito larval food, green algae were collected from mosquito breeding sites and used as larval food. Improvised heater of charcoal stoves and humidifier of wet fabric such as “Kanga” and “Kitenge” were also used. Results and conclusion: There was 90% larval survival, adult mosquito survived much better and the scientists had a total of 467 mosquitoes to run the insecticide susceptibility tests. Innovative ways are necessary under field conditions for mosquito breeding in susceptibility studies. Key words : Malaria, Anopheles gambiae complex, larvae, fabric, resistance, susceptibility, Tanzania.

Maternal overweight/obesity characteristics and child anthropometric status in Jos, Nigeria.

Objective:This study is to determine the pattern of overweight and obesity and its relationship with childhood anthropometric status in Nigeria.Materials and Methods:This cross-sectional study was conducted in Jos, Nigeria. Interviewer administered questionnaire was used in data collection. Maternal and child anthropometric measurements were obtained using standard WHO methods. Child anthropometric Z scores were obtained from WHO Anthroplus while BMI of mothers were also determined. Totally, 262 mother-child pairs were recruited.Results:Mean maternal age and mean child age were 30.8 ± 6.3 yrs (15-47 yrs) and 22.3 ± 18.7 months (3-72 months). Prevalence of maternal underweight, overweight and obesity was 4.2% (11/262), 29.4% (77/262) and 25.9% (68/262), respectively. Child overweight/obesity was 5.4% (14/262), severe under-nutrition 5.7% (15/262). Mean maternal BMI was higher in the older, more educated and higher socioeconomic status (SES). Child mean birth-weight, weight-for-age Z-score and BMI-for-age Z-score (BAZ) were higher among mothers with BMI ≥ 25 kg/m2. All large-for-age babies were in mothers with maternal BMI ≥ 25 kg/m2. Childhood over-nutrition was more common in maternal BMI of ≥25 kg/m2. Overall, BAZ was directly related with maternal BMI, maternal age and birth-weight, although it was inversely related with maternal BM I ≥ 25 kg/m2.Conclusion:Higher BMI is seen in educated and higher SES mothers and this impact on childhood anthropometry.

Bioefficacy of crude extract of Cyperus aromaticus (Family: Cyperaceae) cultured cells, against Aedes aegypti and Aedes albopictus mosquitoes

ObjectiveTo evaluate the growth inhibition activity of the crude extract of Cyperus aromaticus (C. aromaticus) cultured cells against the 3rd instar larvae of Aedes aegypti (Linn.) and Aedes albopictus Skuse (Ae. albopictus) under laboratory conditions, and determine the sublethal effects (EI50) of the crude extract of C. aromaticus cultured cells on some biological and morphological parameters of both Aedes mosquito species during two generations as well. MethodsThe cell suspension cultures of C. aromaticus were activated from five callus lines (P4, Pa, Z1, Z6 and Ml) derived from the root explants of in vitro plantlets. The cultured cells were extracted in chloroform and used as plant material for the present study. For detection of juvenile hormone III, the crude extracts were analyzed by HPLC. Then the crude extracts of the three C. aromaticus cultured cell lines which contained varied amounts of juvenile hormone III [high level (P4 cell line), medium level (Z1 cell line) and low level (Ml cell line)] were tested against Aedes mosquito species. Laboratory evaluation was performed against late third instar larvae of the Vector Control Research Unit strains of Ae. aegypti and Ae. albopictus using the standard WHO method. The effects of EI50 of the C. aromaticus cultured P4 cells on fecundity, fertility, growth period, sex ratio, adult size and longevity of Aedes mosquitoes were assessed. ResultsBioassay tests presented the remarkable growth inhibition activity of the crude extracts of C. aromaticus cultured cells against the two Aedes mosquitoes. Between the two mosquito species, Ae. albopictus was more susceptible to the crude extracts with lower EI50 values. EI50 of the crude extract of C. aromaticus cultured cells (P4) increased the sterility indices in the parental generation females in both Aedes mosquito species. A significant delay in the pupal formation and adult emergence were observed in the parental generation of the both mosquito species. The sex ratio of the adult population either parental or F1 generation of the Aedes mosquito species was not significantly affected by the EI50 dosage of the crude extract of C. aromaticus cultured P4 cells. A significant decrease in the wing length of the treated adult (female and male) of Aedes aegypti as well as the treated female of Ae. albopictus were observed. Longevity of the adult female of the parental generation of both Aedes mosquitoes as well as females of F1 generation of Ae. albopictus were significantly decreased. ConclusionsThe present study revealed the potential of the crude extract of C. aromaticus cultured cells in controlling vector mosquito populations in the effort to reduce the transmission of vector borne diseases.

Performance of Frontloading for Smear Microscopy in the Diagnosis of Pulmonary Tuberculosis: A Cross-Sectional Study at a Referral Hospital in Uganda

ObjectiveTo compare the performance of frontloading and the standard WHO method for diagnosis of pulmonary TB at Mulago Hospital in order to validate the technique in this setting.MethodsThis was a cross-sectional study in which 229 adult (≥18 years) TB suspects were consecutively enrolled. Suspects submitted three sputum samples as follows: at initial presentation, one hour after the first sample, and the next morning. The first and next morning samples formed the standard WHO method, while the first and the one hour later samples formed the frontloading method. Sample processing was by the standard N-acetyl L-cystein (NALC)-NaOH method, and fluorescent microscopy was done for both methods, while cultures of the first sample on Lowenstein-Jensen slants acted as a gold standard. The sensitivity, specificity and predictive values for the WHO standard and frontloading methods were compared.ResultsThe sensitivity of both the frontloading and standard schemes was 91.1% while their specificities were 86.2% and 91.7% respectively. There was excellent agreement between the diagnostic capacity of the two methods (kappa statistic = 0.87, P<0.0001). The positive predictive value for the frontloading scheme was 87.2% and that for the standard approach was 91.9%, while the negative predictive values were 90.4% and 90.9%, respectively. Among the HIV positive patients, frontloading identified 59/79 (74.7%) culture positive samples while the standard approach identified 55/79 (69.6%). In the HIV sero-negative category, on the other hand, front-loading identified 48/110 (43.6%) culture positive samples compared to 45/110 (40.9%) by the standard approach.ConclusionFrontloading based on smear examination of two same-day sputum samples has a similar performance to the current standard method and would not be associated with any significant missed diagnosis. It may therefore be advocated for use in our setting so as to reduce time to completion of diagnosis and patient loss to follow-up.

Evaluation of bioefficacy of α-cypermethrin in long lasting impregnated net (Interceptor®) using analytical method

Objective To evaluate relationship between α-cypermethrin residues in Interceptor® nets by using HPTLC methods and mortality percentage in standard WHO's method “cone test” after repeated washings. Methods Interceptor® containing α-cypermethrin was provided by BASF Company. The washing procedure and bioassay tests were carried out according to the WHO-recommended methods. Malaria vector, An. stephensi was exposed to impregnated bed net for three minutes and then mortality measured after 24 hour recovery period. Chemical analysis was carried out in chemical laboratory by using high performance thin layer chromatography method. Results Result of cone bioassay method showed that washing reduced the efficacy of Interceptor® bed net from 100% in unwashed nets to 15% at 20 washes. After 20 washes, nets contain (61.2±2.8) mg/m 2 resulting 15% mortality in cone test. Killing activity was reduced when nets were washed. Conclusions Results will provide an essential clue for monitoring and evaluation of bioefficacy of any long lasting impregnated bed net for quality control. Findings of this study will be useful for WHO, local investigators and people who wish to use pyrethroidimpregnated bed nets for malaria vector control.

Surveillance of viral haemorrhagic fevers in Ghana: entomological assessment of the risk of transmission in the northern regions

To assess the risk of transmission of viral haemorrhagic fevers in northern Ghana. A two-year cross-sectional entomological study was carried out in four communities in the northern part of Ghana. Standard WHO methods were used to collect adult and larvae of Aedes mosquitoes to estimate man-vector contact rates and larval indices. A total of 2804 households were surveyed to estimate larval indices and man-vector contacts of potential vectors of viral haemorrhagic fevers such as Yellow fever and Dengue. Over 56% households in each study site were positive for Aedes larvae. Relatively higher Breteaux index (BI) and Container index (CI) were estimated in Damongo (BI: 180 and CI: 44.8) and Jirapa (BI: 149.7 and CI: 41.5) compared to Tumu (BI: 76.1 and CI: 19.5) and Bolgatanga (BI: 72.4 and CI: 20.6). Man-biting rates of 9.8 and 18.5 bites /man/hour were estimated for Damongo and Jirapa respectively whilst Bolgatanga recorded 10 B/M/H. Generally, man-vector contact rates in all the study sites were higher during the dry season than the wet season. Larval indices showed seasonal variations and the dry season was identified as the high-risk period for transmission of viral haemorrhagic fevers and possible disease outbreaks. No flavivirus was detected in the 2034 Aedes mosquitoes from the study sites by RT-PCR. Aedes mosquito larval densities and adult biting rates, in all the study areas were sufficient to promote outbreaks of viral haemorrhagic fevers.

Insecticidal Activities of the Leaf Oils of Eight Cinnamomum. species Against Aedes aegypti. and Aedes albopictus.

The leaf oils of eight Cinnamomum. species (C. rhyncophyllum. Miq., C. microphyllum. Ridl., C. pubescens. Kochummen, C. mollissimum. Hook. f., C. impressicostatum. Kosterm, C. scortechinii. Gamb., C. sintoc. Bl., and C. cordatum. Kosterm) were investigated for their larvicidal and adulticidal activities against Aedes aegypti. (Aedes aegypti Lynn) and Aedes albopictus. (Aedes albopictus Skuse). Acute mortalities of the fourth instar larvae and the adult mosquitoes were determined according to the standard WHO methods. Among the essential oils studied, the leaf oils of C. rhyncophyllum., C. microphyllum., C. pubescens., C. mollissimum., and C. impressicostatum. showed significant effects against the larvae of Ae. aegypti. and Ae. albopictus. with concentrations that caused 50% mortality (LC50) values of less than 12.8 and 11.8 µg ml−1, respectively. The essential oils that showed strong larvicidal effects also demonstrated relatively strong adulticidal effects on the mosquitoes after 3 h exposure with LC50 values ranging from 133.0 to 243.0 µg ml−1 against Ae. aegypti. and from 118.0 to 194.0 µg ml−1 against Ae. albopictus.. The efficacy of the oils toward the larvae and adult mosquitoes of both species was nonselective as the LC50 values showed little variation. The chemical composition of the oils was investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). This study suggested that the essential oils containing high levels of benzyl benzoate and benzyl salicylate exhibited strong insecticidal activities against the larvae and adult mosquitoes.

Larvicidal Activity of the Essential Oils and Methanol Extracts of Malaysian Plants on Aedes aegypti

A total of 17 methanol extracts and nine essential oils of Malaysian plants were investigated for their larvicidal activity against Aedes aegypti. Acute mortality of the fourth instar larvae was determined according to the standard WHO method. Among the samples studied, the essential oils of Cinnamomum impressicostatum Kosterm., C. microphyllum Ridl. and Curcuma domestica Valeton showed significant effects with LC 50 values of 13.7, 20.6 and 20.9µg/ml, respectively. Except for Zingiber cassumunar Roxb., the essential oils of the other species were also effective against the larvae with LC 50 values less than 200µg/ml. Of the methanol extracts, Garcinia praniana King, G. griffithii T. Anders, Labisia pumila var. alata Lindl., L. pumila var. pumila and Mitragyna speciosa Korth. showed relatively high activity with LC 50 values ranging from 103-271µg/ml. The methanol extracts were generally less effective than the essential oils with most extracts exhibiting LC 50 values greater than 500µg/ml.

Household survey of locomotor disability caused by poliomyelitis and landmines in Afghanistan

After 19 years of civil war and the total collapse of health services, disabled people are numerous in Afghanistan. Injuries caused by landmines are a major cause of disability,1 but...

Oral health in Latvian 15-year-olds.

Oral hygiene, caries and periodontal conditions were assessed in a representative sample of 15-year-old Latvian schoolchildren, comprising 506 subjects. Caries, diagnosed on the cavity level, was detected in 97.6% of the population. The mean DMFT and DMFS were 8.1 and 14.1, respectively. Although 91% of the children had had restorative treatment, the D component accounted on average for 33% of the DMFS score. Visible dental plaque was found in 98.4% of the children; in a majority (88%) abundant plaque deposits were recorded. Community Periodontal Index of Treatment Needs (CPITN) was assessed by standard WHO methods. Deviation from periodontal health was observed in 90.7% of the children. Calculus was recorded in 26.1% and gingival pockets in 25.9% of the sample. Additionally, 38.7% of the children had gingival bleeding. The mean number of sextants with healthy periodontal conditions was 2.5. Calculus and pocketing averaged 0.6 and 0.4 sextants, respectively. Attachment loss, recorded in 11.7% of the subjects, did not exceed 3 mm. The results showed high caries prevalence, considerable need for treatment and virtual absence of oral hygiene.

Observations on the susceptibility of Ctenocephalides felis (Siphonaptera: Pulicidae) to malathion and permethrin in Tanzania

Laboratory-reared Ctenocephalides felis (Bouche) adults were tested with 0.5% malathion and 0.5% permethrin, using the standard WHO methods. After 24 h exposure to malathion (3.6 mg/cm2), 92% of the fleas died. The LT50 for malathion was approximately 8 h. Permethrin (0.45 mg/cm2) produced 100% mortality of exposed insects after 24 h while with a higher dose (0.9 mg/cm2) all fleas died after 8 h exposure. LT50 for the two doses of permethrin were 7.7 and 1.05 h, respectively. The failure of the diagnostic dose of malathion to kill 100% of the population was attributed to resistance. Permethrin is a suitable pesticide for controlling fleas of domestic animals in Tanzania.