Local prevalence and transmission of avian malaria in the Alakai Plateau of Kauai, Hawaii, U.S.A

Mosquitocidal activities of Chenopodium botrys whole plant n-hexane extract against Culex quinquefasciatus

This research aimed to investigate various mosquitocidal activities of Chenopodium botrys whole- plant n-hexane extract against Culex quinquefasciatus. The extract showed remarkable larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus. During the larvicidal and pupicidal activities, the 24-hour lethal concentration (LC50) of extract against 2nd instar larvae, 4th instar larvae and pupae were 324.6, 495.6 and 950.8 ppm, respectively. During the CDC (Centers for Disease Control and Prevention) bottle bioassay for adulticidal activity, the median knockdown times (KDT50) at 1.25% concentration was 123.4 minutes. During the filter paper impregnation bioassay for adulticidal activity, the KDT50 value at 0.138 mg/cm2 concentration was 48.6 minutes. The extract was fractionated into 14 fractions through silica gel column chromatography which were then combined into six fractions on the basis of similar retention factor (Rf) value. These fractions were screened for adulticidal activity by applying CDC bottle bioassay. The fraction obtained through 60:40 to 50:50% n-hexanes-chloroform mobile phase with 0.5 Rf value showed 100% adulticidal activity at 0.2% concentration. During oviposition deterrent activity, the highest concentration (1000 ppm) showed 71.3 ± 4.4% effective repellence and 0.6 ± 0.1 oviposition activity index. During adult emergence inhibition activity, the median emergence inhibition (EI50) value was 312.3 ppm. From the outcome of the present investigation, it is concluded that the n-hexane extract of C. botrys whole- plant possesses strong larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus.

HAEMOPROTEUS ( PARAHAEMOPROTEUS) SPP. IN CAPTIVE-BRED BOBWHITE QUAIL ( COLINUS VIRGINIANUS) IN SOUTHERN UTAH, USA

A captive-bred Bobwhite Quail ( Colinus virginianus) ranch in southern Utah, US experienced high mortality rates in the late summer and fall of 2012. Nine juvenile birds were necropsied at the Utah Veterinary Diagnostic Laboratory. Gross lesions included pale skeletal muscle with multifocal hemorrhages and petechiae in the air sacs and serosal surfaces of most organs. Histologically there was moderate to severe, multifocal, degenerative myositis with intramyofiber schizonts and minimal lymphoplasmacytic infiltrates in the proventriculus, ventriculus, heart, and skeletal muscle. There was also moderate fibrinoid to heterophilic vasculitis in multiple organs with vascular intraendothelial or intravascular merozoites and scattered thrombosis. In the liver and spleen there were multiple degenerative schizonts that had ruptured. Blood smears from three of the birds were stained with Wright-Giemsa stain and examined at a referral laboratory. Although the blood cells were deteriorated (postmortem artifact), life stages (exact stages not specified) consistent with Haemoproteus spp. were identified in erythrocytes. Polymerase chain reaction done on pooled tissues from two birds produced an amplicon in both pooled samples, and direct sequencing confirmed the presence of 533 base pairs of a Haemoproteus sp. in the subgenus Parahaemoproteus. The identification of Parahaemoproteus spp. in quail in southern Utah implies that appropriate Culicoides spp. vectors are present in the state and that there is potential risk to other birds such as zoo and aviary populations, wild turkeys, and other game birds.

Host species, and not environment, predicts variation in blood parasite prevalence, distribution, and diversity along a humidity gradient in northern South America

Environmental factors strongly influence the ecology and evolution of vector‐borne infectious diseases. However, our understanding of the influence of climatic variation on host–parasite interactions in tropical systems is rudimentary. We studied five species of birds and their haemosporidian parasites (Plasmodium and Haemoproteus) at 16 sampling sites to understand how environmental heterogeneity influences patterns of parasite prevalence, distribution, and diversity across a marked gradient in water availability in northern South America. We used molecular methods to screen for parasite infections and to identify parasite lineages. To characterize spatial heterogeneity in water availability, we used weather‐station and remotely sensed climate data. We estimated parasite prevalence while accounting for spatial autocorrelation, and used a model selection approach to determine the effect of variables related to water availability and host species on prevalence. The prevalence, distribution, and lineage diversity of haemosporidian parasites varied among localities and host species, but we found no support for the hypothesis that the prevalence and diversity of parasites increase with increasing water availability. Host species and host × climate interactions had stronger effects on infection prevalence, and parasite lineages were strongly associated with particular host species. Because climatic variables had little effect on the overall prevalence and lineage diversity of haemosporidian parasites across study sites, our results suggest that independent host–parasite dynamics may influence patterns in parasitism in environmentally heterogeneous landscapes.

Development of an empirical model to predict malaria outbreaks based on monthly case reports and climate variables in Hefei, China, 1990-2011

Malaria remains a significant public health concern in developing countries. Drivers of malaria transmission vary across different geographical regions. Climatic variables are major risk factor in seasonal and secular patterns of P. vivax malaria transmission along Anhui province. The study aims to forecast malaria outbreaks using empirical model developed in Hefei, China. Data on the monthly numbers of notified malaria cases and climatic factors were obtained for the period of January 1st 1990 to December 31st 2011 from the Hefei CDC and Anhui Institute of Meteorological Sciences, respectively. Two logistic regression models with time series seasonal decomposition were used to explore the impact of climatic and seasonal factors on malaria outbreaks. Sensitivity and specificity statistics were used for evaluating the predictive power. The results showed that relative humidity (OR = 1.171, 95% CI = 1.090-1.257), sunshine (OR = 1.076, 95% CI = 1.043-1.110) and barometric pressure (OR = 1.051, 95% CI = 1.003-1.100) were significantly associated with malaria outbreaks after adjustment for seasonality in Hefei area. The validation analyses indicated the overall agreement of 70.42% (sensitivity: 70.52%; specificity: 70.30%). The research suggested that the empirical model developed based on disease surveillance and climatic conditions may have applications in malaria control and prevention activities.