Dengue has become a global public health problem. Despite reactive efforts by the government in Malaysia, the dengue cases are on the increase. Adequate knowledge, positive attitude and correct ...practice for dengue control are essential to stamp out the disease. Hence, this study aims to assess the factors associated with dengue knowledge, attitude and practice (KAP), as well as the association with dengue IgM and IgG seropositivity. A community-based cross-sectional study was conducted in a closed, dengue endemic area with multi-storey dwellings . Five hundred individuals (aged 18 years and above) were approached for pre-tested KAP and seroprevalences assessment. The study showed only half of the total participants have good knowledge (50.7%) but they had insufficient knowledge about dengue during pregnancy. 53.2% of people had poor attitude and 50.2% reported poor practice for dengue control. Out of 85 respondents who agreed to participate in the dengue seroprevalence study, 74.1% (n = 63) were positive for dengue IgG and 7.1% (n = 6) were positive for dengue IgM. Among all sociodemographic variable, race is the only independent predicator for all KAP levels (P < 0.05). In conclusion, proactive and sustainable efforts are needed to bring a behavioural change among communities in order to fight dengue outbreaks in endemic areas.
The elimination of malaria in Southeast Asia has become more challenging as a result of rising knowlesi malaria cases. In addition, naturally occurring human infections with other zoonotic simian ...malaria caused by Plasmodium cynomolgi and Plasmodium inui adds another level of complexity in malaria elimination in this region. Unfortunately, data on vectors which are responsible for transmitting this zoonotic disease is very limited.
We conducted longitudinal studies to investigate the entomological parameters of the simian malaria vectors and to examine the genetic diversity and evolutionary pattern of their simian Plasmodium. All the captured Anopheles mosquitoes were dissected to examine for the presence of oocysts, sporozoites and to determine the parous rate. Our study revealed that the Anopheles Leucosphyrus Group mosquitoes are highly potential competent vectors, as evidenced by their high rate of parity, survival and sporozoite infections in these mosquitoes. Thus, these mosquitoes represent a risk of human infection with zoonotic simian malaria in this region. Haplotype analysis on P. cynomolgi and P. inui, found in high prevalence in the Anopheles mosquitoes from this study, had shown close relationship between simian Plasmodium from the Anopheles mosquitoes with its vertebrate hosts. This directly signifies the ongoing transmission between the vector, macaques, and humans. Furthermore, population genetic analysis showed significant negative values which suggest that both Plasmodium species are undergoing population expansion.
With constant microevolutionary processes, there are potential for both P. inui and P. cynomolgi to emerge and spread as a major public health problem, following the similar trend of P. knowlesi. Therefore, concerted vector studies in other parts of Southeast Asia are warranted to better comprehend the transmission dynamics of this zoonotic simian malaria which eventually would aid in the implementation of effective control measures in a rapidly changing environment.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Dengue continues to be a major public health problem in many parts of the world. Vector control is the hallmark of dengue control programme in most countries in Southeast Asia. However, it is known ...that the current program lacks sensitivity and proactivity. It is also known that asymptomatic people are infectious to mosquitoes and this could be a reason for increase in cases with current ongoing surveillance measures. A randomised control trial was conducted to determine the efficacy of a combination of gravid oviposition sticky (GOS) traps and dengue non-structural 1 (NS1) antigen for early surveillance of dengue among Aedes mosquitoes. GOS traps were set weekly at the intervention apartments to trap the Aedes mosquitoes and these were tested with NS1 antigen kits. Dengue cases in the intervention arm were less than the control arm. Detection of NS1 positive mosquitoes were significantly associated with GOS Aedes index (rs= 0.68 P<0.01) and occurrence of dengue cases (rs=0.31 P<0.01). The result of this randomized control trial further supports the notion that dengue surveillance using GOS trap and dengue NS1 test can detect dengue-positive mosquitoes before dengue cases were reported. Moreover, the significant positive correlation of dengue cases with the number of NS1 positive mosquito pool shows detection of dengue positive mosquito can be used as an indicator of viral transmission. To the best of our knowledge, this is the first study that demonstrates a dengue surveillance system which is able to capture asymptomatic, dengue-viraemic individuals living in an area with infected mosquitoes. In conclusion infected Aedes mosquitoes can serve as an early warning and identification of such mosquitoes should be the way forward for proactive dengue surveillance and control measures.
Abstract
Land-use changes, such as deforestation and agriculture, can influence mosquito vector populations and malaria transmission. These land-use changes have been linked to increased incidence in ...human cases of the zoonotic malaria
Plasmodium knowlesi
in Sabah, Malaysian Borneo. This study investigates whether these associations are partially driven by fine-scale land-use changes creating more favourable aquatic breeding habitats for
P. knowlesi
anopheline vectors. Using aerial remote sensing data, we developed a sampling frame representative of all land use types within a major focus of
P. knowlesi
transmission. From 2015 to 2016 monthly longitudinal surveys of larval habitats were collected in randomly selected areas stratified by land use type. Additional remote sensing data on environmental variables, land cover and landscape configuration were assembled for the study site. Risk factor analyses were performed over multiple spatial scales to determine associations between environmental and spatial variables and anopheline larval presence. Habitat fragmentation (300 m), aspect (350 m), distance to rubber plantations (100 m) and
Culex
larval presence were identified as risk factors for
Anopheles
breeding. Additionally, models were fit to determine the presence of potential larval habitats within the areas surveyed and used to generate a time-series of monthly predictive maps. These results indicate that land-use change and topography influence the suitability of larval habitats, and may partially explain the link between
P. knowlesi
incidence and deforestation. The predictive maps, and identification of the spatial scales at which risk factors are most influential may aid spatio-temporally targeted vector control interventions.
We detected the simian malaria parasites Plasmodium knowlesi, P. cynomolgi, P. inui, P. coatneyi, P. inui–like, and P. simiovale among forest fringe–living indigenous communities from various ...locations in Malaysia. Our findings underscore the importance of using molecular tools to identify newly emergent malaria parasites in humans.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Plasmodium knowlesi, a simian malaria parasite, has been in the limelight since a large focus of human P. knowlesi infection was reported from Sarawak (Malaysian Borneo) in 2004. Although this ...infection is transmitted across Southeast Asia, the largest number of cases has been reported from Malaysia. The increasing number of knowlesi malaria cases has been attributed to the use of molecular tools for detection, but environmental changes including deforestation likely play a major role by increasing human exposure to vector mosquitoes, which coexist with the macaque host. In addition, with the reduction in human malaria transmission in Southeast Asia, it is possible that human populations are at a greater risk of P. knowlesi infection due to diminishing cross-species immunity. Furthermore, the possibility of increasing exposure of humans to other simian Plasmodium parasites such as Plasmodium cynomolgi and Plasmodium inui should not be ignored. We here review the current status of these parasites in humans, macaques, and mosquitoes to support necessary reorientation of malaria control and elimination in the affected areas.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Blood feeding and host-seeking behaviors of a mosquito play an imperative role in determining its vectorial capacity in transmitting pathogens. Unfortunately, limited information is available ...regarding blood feeding behavior of Anopheles species in Malaysia. Collection of resting Anopheles mosquitoes for blood meal analysis poses a great challenge especially for forest dwelling mosquitoes. Therefore, a laboratory-based study was conducted to evaluate the potential use of mosquitoes caught using human landing catch (HLC) for blood meal analysis, and subsequently to document blood feeding behavior of local Anopheles mosquitoes in Peninsular Malaysia. The laboratory-based experiment from this study revealed that mosquitoes caught using HLC had the potential to be used for blood meal analysis. Besides HLC, mosquitoes were also collected using manual aspirator and Mosquito Magnet. Overall, 47.4% of 321 field-caught Anopheles mosquitoes belonging to six species were positive for vertebrate host DNA in their blood meal. The most frequent blood meal source was human (45.9%) followed by wild boar (27.4%), dog (15.3%) and monkey (7.5%). Interestingly, only Anopheles cracens and Anopheles introlatus (Leucosphyrus Group) fed on monkey. This study further confirmed that members of the Leucosphyrus Group are the predominant vectors for knowlesi malaria transmission in Peninsular Malaysia mainly due to their simio-anthropophagic feeding behavior.
Human movement into insect vector and wildlife reservoir habitats determines zoonotic disease risks; however, few data are available to quantify the impact of land use on pathogen transmission. Here, ...we utilise GPS tracking devices and novel applications of ecological methods to develop fine-scale models of human space use relative to land cover to assess exposure to the zoonotic malaria
in Malaysian Borneo. Combining data with spatially explicit models of mosquito biting rates, we demonstrate the role of individual heterogeneities in local space use in disease exposure. At a community level, our data indicate that areas close to both secondary forest and houses have the highest probability of human
exposure, providing quantitative evidence for the importance of ecotones. Despite higher biting rates in forests, incorporating human movement and space use into exposure estimates illustrates the importance of intensified interactions between pathogens, insect vectors and people around habitat edges.
We detected 2 natural, asymptomatic Plasmodium inui monoinfections in humans in Malaysia by using nested PCR on concentrated high-volume blood samples. We found a P. inui–positive Anopheles cracens ...mosquito in the same site as the human infections. Investigators should use ultrasensitive detection methods to identify simian malaria parasite transmission in humans.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Dengue remains a major public threat and existing dengue control/surveillance programs lack sensitivity and proactivity. More efficient methods are needed. A cluster randomized controlled trial was ...conducted for 18 months to determine the efficacy of using a combination of gravid oviposition sticky (GOS) traps and dengue non-structural 1 (NS1) antigen for early surveillance of dengue among Aedes mosquito. Eight residential apartments were randomly assigned into intervention and control groups. GOS traps were placed at the intervention apartments weekly to trap Aedes mosquitoes and these tested for dengue NS1 antigen. When dengue-positive pool was detected, the community were notified and advised to execute protective measures. Fewer dengue cases were recorded in the intervention group than the control. Detection of NS1-positive mosquitoes was significantly associated with GOS Aedes index (r
= 0.68, P < 0.01) and occurrence of dengue cases (r
= 0.31, P < 0.01). Participants' knowledge, attitude, and practice (KAP) toward dengue control indicated significant improvement for knowledge (P < 0.01), practice (P < 0.01) and total scores (P < 0.01). Most respondents thought this surveillance method is good (81.2%) and supported its use nationwide. Thus, GOS trap and dengue NS1 antigen test can supplement the current dengue surveillance/control, in alignment with the advocated integrated vector management for reducing Aedes-borne diseases.
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