Regime shifts and heterogeneous trends in malaria time series from Western Kenya Highlands

Large malaria epidemics in the East African highlands during the mid and late 1990s kindled a stream of research on the role that global warming might have on malaria transmission. Most of the inferences using temporal information have been derived from a malaria incidence time series from Kericho. Here, we report a detailed analysis of 5 monthly time series, between 15 and 41 years long, from West Kenya encompassing an altitudinal gradient along Lake Victoria basin. We found decreasing, but heterogeneous, malaria trends since the late 1980s at low altitudes (<1600 m), and the early 2000s at high altitudes (>1600 m). Regime shifts were present in 3 of the series and were synchronous in the 2 time series from high altitudes. At low altitude, regime shifts were associated with a shift from increasing to decreasing malaria transmission, as well as a decrease in variability. At higher altitudes, regime shifts reflected an increase in malaria transmission variability. The heterogeneity in malaria trends probably reflects the multitude of factors that can drive malaria transmission and highlights the need for both spatially and temporally fine-grained data to make sound inferences about the impacts of climate change and control/elimination interventions on malaria transmission

The diving beetles of Kamchatka, with additional records from Sakhalin and the Kuril Islands (Coleoptera: Dytiscidae).

Die Dytiscidenfauna der nordostasiatischen Halbinsel Kamtschatka wird auf der Grundlage von Literaturnachweisen und neueren Aufsammlungen zusammengestellt. Die folgenden zehn Arten werden erstmals für Kamtschatka nachgewiesen: Hygrotus marklini (Gyllenhal), Hydroporus notabilis LeConte, H. submuticus Thomson, H. tristis (Paykull), H. uenoi Nakane, Oreodytes okulovi Lafer, Agabus balkei Fery & Nilsson, A. discolor Harris, Ilybius chishimanus Kôno, Rhantus suturellus (Harris), und Graphoderus perplexus Sharp. Insgesamt 38 Dytiscidenarten, davon 22 mit holarktischer Verbreitung, sind nun von Kamtschatka bekannt. Graphoderus perplexus wird erstmals aus der Paläarktis nachgewiesen. Weitere Nachweise werden für Sachalin und die Kurilen genannt. Die folgenden Arten sind Erstnachweise für Sachalin: Hydroporus nigellus Mannerheim, Agabus kholini Nilsson, Ilybius angustior (Gyllenhal), und Acilius canaliculatus (Nicolai). Zehn Arten werden erstmals für die Kurilen nachgewiesen: Hydroporus nigellus, H. notabilis, H. submuticus, H. tristis, Agabus clypealis (Thomson), A. confinis (Gyllenhal), A. costulatus (Motschulsky), A. discolor, Ilybius discedens Sharp, und Colymbetes dahuricus Aubé. Neun dieser Arten wurden auf den nördlichen, H. tristis dagegen auf den südlichen Kurilen gefunden. Damit sind jetzt von Sachalin 39 und von den Kurilen 36 Arten bekannt.The dytiscid fauna of the north-east Asian peninsula Kamchatka is reviewed based on literature records and more recent collections. The following ten species are here reported from Kamchatka for the first time: Hygrotus marklini (Gyllenhal), Hydroporus notabilis LeConte, H. submuticus Thomson, H. tristis (Paykull), H. uenoi Nakane, Oreodytes okulovi Lafer, Agabus balkei Fery & Nilsson, A. discolor Harris, Ilybius chishimanus Kôno, Rhantus suturellus (Harris), and Graphoderus perplexus Sharp. Altogether 38 species of Dytiscidae are now known from Kamchatka, and of these 22 have Holarctic distributions. Graphoderus perplexus is here reported for the Palearctic Region for the first time. Additional records are given for Sakhalin and the Kuril Islands. The following four species are here reported from Sakhalin for the first time: Hydroporus nigellus Mannerheim, Agabus kholini Nilsson, Ilybius angustior (Gyllenhal), and Acilius canaliculatus (Nicolai). The following ten species are here reported from the Kuril Islands for the first time: Hydroporus nigellus, H. notabilis, H. submuticus, H. tristis, Agabus clypealis (Thomson), A. confinis (Gyllenhal), A. costulatus (Motschulsky), A. discolor, Ilybius discedens Sharp, and Colymbetes dahuricus Aubé. Nine of the species were found in the North Kurils, whereas H. tristis was found in the South Kurils. With these additions, 39 species are now known from Sakhalin, and 36 from the Kuril Islands

Population genetic structure of Anopheles gambiae mosquitoes on Lake Victoria islands, west Kenya

BACKGROUND: Understanding the genetic structure of island Anopheles gambiae populations is important for the current tactics in mosquito control and for the proposed strategy using genetically-modified mosquitoes (GMM). Genetically-isolated mosquito populations on islands are a potential site for testing GMM. The objective of this study was to determine the genetic structure of A. gambiae populations on the islands in Lake Victoria, western Kenya. METHODS: The genetic diversity and the population genetic structures of 13 A. gambiae populations from five islands on Lake Victoria and six villages from the surrounding mainland area in the Suba District were examined using six microsatellite markers. The distance range of sampling sites varied between 2.5 and 35.1 km. RESULTS: A similar level of genetic diversity between island mosquito populations and adjacent mainland populations was found. The average number of alleles per locus was 7.3 for the island populations and 6.8 for the mainland populations. The average observed heterozygosity was 0.32 and 0.28 for the island and mainland populations, respectively. A low but statistically significant genetic structure was detected among the island populations (F(ST )= 0.019) and between the island and mainland populations (F(ST )= 0.003). A total of 12 private alleles were found, and nine of them were from the island populations. CONCLUSION: A level of genetic differentiation between the island and mainland populations was found. Large extent of gene flow between the island and mainland mosquito populations may result from wind- or human-assisted dispersal. Should the islands on Lake Victoria be used as a trial site for the release program of GMM, mosquito dispersal between the islands and between the island and the mainland should be vigorously monitored

The diving beetles of the Kuril Archipelago in the Far East of Russia (Coleoptera: Dytiscidae).

Nach Literaturangaben sowie Untersuchungen von Museumsmaterial und Ausbeuten der in den letzten Jahren durchgeführten Expeditionen sind die Schwimmkäfer (Dytiscidae) auf den Kurilen im Nordwest-Pazifik mit 24 Arten vertreten. Über die 357 adulten und 50 larvalen Dytisciden, die während der gemeinsamen amerikanisch-japanisch-russischen Expedition 1994 und 1995 auf den südlichen und mittleren Kurilen gesammelt wurden, wird detailliert berichtet. Die folgenden fünf Arten werden erstmals für die Kurilen nachgewiesen: Hydroporus uenoi Nakane, Platambus pictipennis (Sharp), Agabus japonicus Sharp, Ilybius nakanei Nilsson, und Graphoderus zonatus (Hoppe). Die Zahl der auf den einzelnen Inseln festgestellten Arten lag zwischen 1 und 11; den höchsten Artenreichtum zeigen die größten Inseln auf beiden Seiten des Großen Kurilen-Kamms. Auf den südlichen Kurilen dominieren die ussurisch-japanischen Arten, die auch von Sakhalin und Hokkaido bekannt sind, während sich die Fauna der nördlichen Kurilen durch einen hohen Anteil holarktischer und paläarktischer Arten auszeichnet, die auch in Kamtschatka vorkommen.The species of predaceous diving beetles (Coleoptera, Dytiscidae) ocurring in the Kuril Archipelago in the northwest Pacific are reviewed. Based on literature records, the study of museum collections, and material from recent expeditions 24 species are known from the archipelago. A detailed report is given on the 357 adult and 50 larval specimens collected in the South and Mid Kuril Islands by the joint American-Japanese-Russian expeditions in 1994 and 1995. The following five species are here recorded from the Kurils for the first time: Hydroporus uenoi Nakane, Platambus pictipennis (Sharp), Agabus japonicus Sharp, Ilybius nakanei Nilsson, and Graphoderus zonatus (Hoppe). The number of species recorded on individual islands ranged from 1 to 11, with the largest islands at either end of the Greater Kuril Ridge being the most diverse. The South Kurils are dominated by Ussurian-Japanese species known also from Sakhalin and Hokkaido, whereas the North Kuril fauna includes a high proportion of Holarctic or Palearctic species known also from Kamchatka

Community-wide benefits of targeted indoor residual spray for malaria control in the Western Kenya Highland

<p>Abstract</p> <p>Background</p> <p>Interest in indoor residual spray (IRS) has been rekindled in recent years, as it is increasingly considered to be a key component of integrated malaria management. Regular spraying of each human dwelling becomes less and less practical as the control area increases. Where malaria transmission is concentrated around focal points, however, targeted IRS may pose a feasible alternative to mass spraying. Here, the impact of targeted IRS was assessed in the highlands of western Kenya.</p> <p>Methods</p> <p>Indoor residual spray using lambda-cyhalothrin insecticide was carried out during the last week of April 2005 in 1,100 targeted houses, located in the valley bottom areas of Iguhu village, Kakamega district of western Kenya. Although the uphill areas are more densely populated, valleys are believed to be malaria transmission hotspots. The aim of the study was to measurably reduce the vector density and malaria transmission in uphill areas by focusing control on these hotspots. A cohort of 1,058 children from 1-5 yrs of age was randomly selected from a 4 km by 6 km study area for the baseline malaria prevalence survey after pre-clearing malaria infections during the third week of April 2005, and the prevalence of <it>Plasmodium </it>infections was tested bi-weekly. Seasonal changes in mosquito densities 12 months before the IRS and 12 months after the IRS was monitored quarterly based on 300 randomly selected houses. Monthly parasitological surveys were also carried out in the same area with 129-661 randomly selected school children of age 6-13 yrs.</p> <p>Results</p> <p>The result of monthly parasitological surveys indicated that malaria prevalence in school children was reduced by 64.4% in the intervention valley area and by 46.3% in the intervention uphill area after 12 months of follow-ups in contrast to nonintervention areas (valley or uphill). The cohort study showed an average of 4.5% fewer new infections biweekly in the intervention valley compare to nonintervention valley and the relative reduction in incidence rate by week 14 was 65.4%. The relative reduction in incidence rate in intervention uphill by week 14 was 46.4%. <it>Anopheles gambiae </it>densities were reduced by 96.8% and 51.6% in the intervention valley and intervention uphill, respectively, and <it>Anopheles funestus </it>densities were reduced by 85.3% and 69.2% in the intervention valley and intervention uphill, respectively.</p> <p>Conclusion</p> <p>Vector control had significant indirect impact on the densely populated uphill areas when IRS was targeted to the high-risk valleys. Additionally, the wide-reaching benefits of IRS in reducing vector prevalence and disease incidence was observed for at least six months following spraying, suggesting targeted IRS as an effective tool in malaria control.</p

A comparative study of dengue virus vectors in major parks and adjacent residential areas in Ho Chi Minh City, Vietnam

The primary dengue virus vectors, Aedes aegypti and Aedes albopictus, are primarily daytime biting mosquitoes. The risk of infection is suspected to be considerable in urban parks due to visitor traffic. Despite the importance of vector control for reducing dengue transmission, little information is available on vector populations in urban parks. The present study characterized mosquito habitats and estimated vector densities in the major urban parks in Ho Chi Minh City, Vietnam and compared them with those in adjacent residential areas. The prevalences of habitats where Aedes larvae were found were 43% and 9% for the parks and residential areas, respectively. The difference was statistically significant (prevalence ratio [PR]: 5.00, 95% CI: 3.85–6.49). The prevalences of positive larval habitats were significantly greater in the parks for both species than the residential areas (PR: 1.52, 95% CI: 1.04–2.22 for A. aegypti, PR: 10.10, 95% CI: 7.23–14.12 for A. albopictus). Larvae of both species were positively associated with discarded containers and planters. Aedes albopictus larvae were negatively associated with indoor habitats, but positively associated with vegetation shade. The adult density of A. aegypti was significantly less in the parks compared with the residential areas (rate ratio [RR]; 0.09, 95% CI: 0.05–0.16), while the density of A. albopictus was significantly higher in the parks (RR: 9.99, 95% CI: 6.85–14.59). When the species were combined, the density was significantly higher in the parks (RR: 2.50, 95% CI: 1.92–3.25). The urban parks provide suitable environment for Aedes mosquitoes, and A. albopictus in particular. Virus vectors are abundant in the urban parks, and the current vector control programs need to have greater consideration of urban parks

Novel Antiviral Efficacy of Hedyotis diffusa and Artemisia capillaris Extracts against Dengue Virus, Japanese Encephalitis Virus, and Zika Virus Infection and Immunoregulatory Cytokine Signatures

Currently, there are no specific therapeutics for flavivirus infections, including dengue virus (DENV) and Zika virus (ZIKV). In this study, we evaluated extracts from the plants Hedyotis diffusa (HD) and Artemisia capillaris (AC) to determine the antiviral activity against DENV, ZIKV, and Japanese encephalitis virus (JEV). HD and AC demonstrated inhibitory activity against JEV, ZIKV, and DENV replication and reduced viral RNA levels in a dose–responsive manner, with non-cytotoxic concentration ranging from 0.1 to 10 mg/mL. HD and AC had low cytotoxicity to Vero cells, with CC50 values of 33.7 ± 1.6 and 30.3 ± 1.7 mg/mL (mean ± SD), respectively. The anti-flavivirus activity of HD and AC was also consistent in human cell lines, including human glioblastoma (T98G), human chronic myeloid leukemia (K562), and human embryonic kidney (HEK-293T) cells. Viral-infected, HD-treated cells demonstrated downregulation of cytokines including CCR1, CCL26, CCL15, CCL5, IL21, and IL17C. In contrast, CCR1, CCL26, and AIMP1 were elevated following AC treatment in viral-infected cells. Overall, HD and AC plant extracts demonstrated flavivirus replication inhibitory activity, and together with immunoregulatory cytokine signatures, these results suggest that HD and AC possess bioactive compounds that may further be refined as promising candidates for clinical applications

Indian Ocean Dipole and Rainfall Drive a Moran Effect in East Africa Malaria Transmission

Background. Patterns of concerted fluctuation in populations-synchrony-can reveal impacts of climatic variability on disease dynamics. We examined whether malaria transmission has been synchronous in an area with a common rainfall regime and sensitive to the Indian Ocean Dipole (IOD), a global climatic phenomenon affecting weather patterns in East Africa.Methods.We studied malaria synchrony in 5 15-year long (1984-1999) monthly time series that encompass an altitudinal gradient, approximately 1000 m to 2000 m, along Lake Victoria basin. We quantified the association patterns between rainfall and malaria time series at different altitudes and across the altitudinal gradient encompassed by the study locations.Results.We found a positive seasonal association of rainfall with malaria, which decreased with altitude. By contrast, IOD and interannual rainfall impacts on interannual disease cycles increased with altitude. Our analysis revealed a nondecaying synchrony of similar magnitude in both malaria and rainfall, as expected under a Moran effect, supporting a role for climatic variability on malaria epidemic frequency, which might reflect rainfall-mediated changes in mosquito abundance.Conclusions.Synchronous malaria epidemics call for the integration of knowledge on the forcing of malaria transmission by environmental variability to develop robust malaria control and elimination programs

Diving behavior in Anopheles gambiae (Diptera: Culicidae): avoidance of a predacious wolf spider (Araneae: Lycosidae) in relation to life stage and water depth.

It has been suggested that mosquito larvae and pupae dive to avoid predators. We tested this predator-avoidance hypothesis by using immature Anopheles gambiae Giles (Diptera: Culicidae) and the wolf spider Pardosa messingerae (Stand) (Araneae: Lycosidae). Because previous studies have suggested that wolf spiders are poor predators of immature mosquitoes, we first examined the predatory ability of the wolf spider and found that the spider was effective at capturing all stages of larvae and pupae. The mortality from experimental cups containing deep water increased with the age of mosquitoes, with the exception of pupae. In contrast, this trend was not observed in shallow water. In particular, mortality was significantly lower in deep water during the second instar. During the third instar, the opposite trend was observed. When the effect of cannibalism was excluded by subtracting the number of missing mosquitoes for the treatment without spiders from those with spiders, the cannibalism corrected mortality was significantly lower in deep water during the second instar. The duration of diving by larvae and pupae decreased with age. With the exception of first instar, diving frequency also decreased with age. We postulate that this diving behavior allows An. gambiae to escape predation by wolf spiders, which supports the predator-avoidance hypothesis. This study indicates some important implications for vector control