Aedes aegypti abundance, larval indices and risk for dengue virus transmission in Kinondoni district, Tanzania

Background Tanzania has experienced periodic dengue outbreaks with increased incidence since 2010. However, there is limited information on vector dynamics and transmission risk in most parts of the country. This study was conducted to determine Aedes mosquito abundance, larval indices and dengue virus infection rate as risk indicators for DENV transmission in Kinondoni district, Dar es Salaam, Tanzania. Methods A cross-sectional study was conducted in three wards of Kinondoni district in Tanzania between December 2019 and January 2020. In each ward, three streets were randomly selected for adult and immature mosquito sampling. The adult mosquitoes were collected using Mosquito Magnet traps, while mosquito larvae and pupae were inspected in water-holding containers in the selected household compounds. The detection of dengue virus (DENV) in female Aedes mosquitoes was done using a one-step reverse transcription–polymerase chain reaction (RT–PCR) method. Results Of the 1416 adult female mosquitoes collected, Ae. aegypti accounted for 16.8% (n = 238). A total of 333 water-holding containers were inspected and 201 (60.4%) had at least an Aedes larvae or pupae. Water-holding containers supporting the breeding of Aedes larvae and pupae included discarded car tires, flowerpots and small and large plastic containers. The overall House Index, Container Index and Breteau Index were 55.1%, 60.4% and 114.2, respectively. None of the 763 female Aedes mosquitoes tested by RT–PCR was found to be infected with DENV. Conclusion The presence and abundance Ae. aegypti mosquitoes and the large proportion of water-holding containers infested with the mosquito larvae and pupae put residents of Kinondoni district at high risk of DENV transmission. Our findings emphasize the need for continuous mosquito vector surveillance and control to prevent the possibility of future DENV outbreaks in Tanzania.

Detection of Zika virus in Anopheles stephensi Liston, 1901 (Diptera: Culicidae) in India - First report

Zika virus (ZIKV) a mosquito-borne, causing acute febrile illness associated with rash, arthralgia and conjunctivitis in the patient, was reported from Thiruvananthapuram, Kerala, as an outbreak with 83 cases. Entomological surveillance revealed the presence of aedine mosquitoes viz., Aedes aegypti (Linnaeus, 1762), Ae. albopictus (Skuse, 1894) and Ae. vittatus (Bigot, 1861) and nonaedine mosquitoes viz., Anopheles stephensi Liston,1901, Mansonia uniformis (Theobald, 1901), Culex tritaeniorhynchus Giles, 1901 and Cx. gelidus Theobald,1901. Aedes (Ae. aegypti, Ae. vittatus and Ae. Albopictus) mosquito larvae were high in the Zika affected areas. Moreover ZIKV was detected in An. stephensi mosquitoes collected from Parassala, Thiruvananthapuram (the native place of the first ZIKV confirmed case in the present outbreak in Kerala). Molecular diagnostics of Ae. Aegypti, Ae. vittatu and An. stephensi mosquitoes revealed that the species were loaded with ZIKV. Significantly this is the first ever report of ZIKV detecting in An. stephensi in the world. Aedes adults (male and female) and An. stephensi emerged from fourth instar larvae and pupae were found to have ZIKV, indicating transovarial transmission of the virus.

Efektifitas kegiatan pelatihan pembuatan ovitrap DBD pada santri Pondok Pesantren Al Falah Banjarbaru

The negative impact of the insecticides usage triggers the development of new methods other than insecticides, one f them is ovitrap tools (mosquito egg traps). The use of ovitrap as part of dengue prevention efforts has proven to be easy, cheap, safe for health and environmentally friendly. Ovitrap is effective in reducing mosquito populations. The purpose of the activity is to analyze the knowledge, attitudes and actions of students in the use of ovitrap as an effort to control Aedes sp mosquito larvae after the implementation of health counseling activities and demonstrations of making Ovitrap. All students at Pondok Pesantren Al Falah Putera became the population. As many as 96 students who were willing and involved in this activity became the research sample. McNemar test showed significant results on knowledge (0.018), attitude (0.033) and action (0.00). The making andthe use of Ovitrap socialization still needs to be sought in order to increase the Santri knowlwege.. It is hoped that this activity can be implemented every year as an effort to reduce the risk of dengue fever in Banjarbaru Cit

Culex quinquefasciatus larvae development arrested when fed on Neochloris aquatica

Culex quinquefasciatus is a cosmopolitan species widely distributed in the tropical and subtropical areas of the world. Due to its long history of close association with humans, the transmission of arboviruses and parasites have an important role in veterinary and public health. Adult females feed mainly on birds although they can also feed on humans and other mammals. On the other hand, larvae are able to feed on a great diversity of microorganisms, including microalgae, present in natural or artificial breeding sites with a high organic load. These two particularities, mentioned above, are some of the reasons why this mosquito is so successful in the environment. In this work, we report the identification of a microalga found during field sampling in artificial breeding sites, in a group of discarded tires with accumulated rainwater. Surprisingly, only one of them had a bright green culture without mosquito larvae while the other surrounding tires contained a large number of mosquito larvae. We isolated and identified this microorganism as Neochloris aquatica, and it was evaluated as a potential biological control agent against Cx. quinquefasciatus. The oviposition site preference in the presence of the alga by gravid females, and the effects on larval development were analyzed. Additionally, microalga effect on Cx. quinquefasciatus wild type, naturally infected with the endosymbiotic bacterium Wolbachia (w+) and Wolbachia free (w−) laboratory lines was explored. According to our results, even though it is chosen by gravid females to lay their eggs, the microalga had a negative effect on the development of larvae from both populations. Additionally, when the larvae were fed with a culture of alga supplemented with balanced fish food used as control diet, they were not able to reverse its effect, and were unable to complete development until adulthood. Here, N. aquatica is described as a biological agent, and as a potential source of bioactive compounds for the control of mosquito populations important in veterinary and human health.

HUBUNGAN KARAKTERISTIK SUMUR GALI DENGAN KEBERADAAN JENTIK NYAMUK AEDES AEGYPTI DI DESA SALO TIMUR KECAMATAN SALO TAHUN 2020

Keberadaan jentik nyamuk Aedes aegypti dalam sumur gali sebagai tempat penampungan air alamiah dapat dipengaruhi beberapa faktor. Keberadaan jentik Aedes aegypti dapat ditemukan pada genangan air bersih dan tidak mengalir, terbuka serta terlindung dari cahaya matahari. Lingkungan tempat penduduk adalah tempat perindukan nyamuk oleh karena itu masyarakat harus menjaga kebersihan lingkungan disekitar rumah dan tidak ada tempat atau media yang dapat menjadi tempat perindukan nyamuk. Tujuan penelitian ini adalah untuk mengetahui karakteristik sumur gali yang berpotensi menjadi tempat perkembangbiakan nyamuk Aedes aegypti di Desa Salo Timur Kecamatan Salo Tahun 2020. Jenis penelitian ini adalah explanatory research dengan pendekatan cross sectional. Populasi penelitian adalah sumur gali yang berada di Desa Salo Timur sejumlah 1033 sumur gali dan diperoleh 280 sampel. Pengambilan sampel menggunakan metode Purposive Sampling. Hasil penelitian menunjukan ada hubungan antara letak sumur gali (nilai p=0,012), keberadaan penutup sumur gali (nilai p=0,000), pH sumur gali (nilai p=0,000), dan Pencahayaan Sumur Gali (nilai p=0,000) dengan keberadaan jentik nyamuk Aedes aegypti. The larvae exitence in dug wells where it is a place of collecting and saving water were influenced by some factors. The presence of Aedes aegypti mosquito larvae can be found in stagnant water that does not flow, open, and protected from sunlight. The environment where residents are breeding palces for mosquitoes is therefore the community must maintain the cleanliness of the environment around the house and there is no place or media that can become mosquito breeding places. The purpose of this study determined the characteristics of dug wells that could potentially become a breeding Aedes aegypti mosquito in Salo Timur Village, Salo District in 2020 This type of research was explanatory research which using cross sectional approach. The population of this research were dug wells around in the village of East Salo with a total of 1033 dug wells and 280 samples were obtained. Sampling using the Purposive Sampling method. The results showed there was a relationship between the location of dug wells (p = 0.012), the presence of dug well cover (p = 0,000), pH of dug wells (p = 0,000) and dug well lighting (p=0,000) with the presence of Aedes aegypti mosquito larvae. Suggestion, improve sanitation of dug wells to prevent mosquitoes from breeding.

Species diversity and breeding site of mosquito larvae (Diptera: Culicidae) in Macaca fascicularis breeding area

Mosquito larvae play an essential role in the ecological, and many of them can spread human and animal diseases, including in Macaca fascicularis. Information on mosquito species and their habitats can provide an overview of the role of mosquitoes in the spread of vector-borne diseases in M. fascicularis captivity area. This study aimed to identify species diversity of mosquito larvae, species affinity and association, and the larval breeding sites around M. fascicularis captivity area in Bogor, West Java. Mosquito larvae were collected from 102 sites using a 350 ml dipper. Mosquito larvae that were successfully collected consisted of 11 species; Aedes albopictus, Ae. aegypti, Armigeres subalbatus, Anopheles aconitus, An. kochi, An. vagus, Culex fuscocephala, Cx. pseudovishnui, Cx. tritaeniorhyncus, Cx. quinquefasciatus, and Cx. vishnui. Co-occurrence in mosquito larvae as many as 13 compositions, with the highest co-occurrence in Ae. albopictus and Cx. quinquefasciatus that was 11 times. There were seven types breeding sites for the larval mosquitoes, i.e containers, ditches, creeks, ponds, artificial ponds, groundwater puddles, and rice fields. We conclude the existence of mosquito larvae and the availability of their breeding site in M. fascicularis captivity area can be a potential transmission of pathogens between mosquitoes and hosts

Circulating dengue virus serotypes and vertical transmission in Aedes larvae during outbreak and inter-outbreak seasons in a high dengue risk area of Sri Lanka

Background Spatial and temporal changes in the dengue incidence are associated with multiple factors, such as climate, immunity among a population against dengue viruses (DENV), circulating DENV serotypes and vertical transmission (VT) of DENV in an area at a given time. The level of VT in a specific location has epidemiological implications in terms of viral maintenance in vectors. Identification of the circulating DENV serotypes in both patients and Aedes mosquito larvae in an area may be useful for the early detection of outbreaks. We report here the results of a prospective descriptive study that was conducted to detect the levels of VT in Aedes mosquito larvae and circulating DENV serotypes in patients and Aedes mosquito larvae from December 2015 to March 2017 in an area of Sri Lanka at high risk for dengue. Methods A total of 200 patients with clinically suspected dengue who had been admitted to a tertiary care hospital during a dengue outbreak (3 study periods: December 2015–January 2016, June–August 2016, December 2016–January 2017) and in the inter-outbreak periods (February–May 2016 and September–November 2016) were investigated. Blood samples were drawn from the study participants to test for DENV. The houses of the study participants were visited within 7 days of admission to the hospital, and Aedes larvae were also collected within a radius of 400 m from the houses. The larvae were separately identified to species and then pooled according to each patient’s identification number. Patients’ sera and the Aedes larvae were tested to identify the infecting DENV serotypes using a reverse transcription PCR (RT-PCR) method. Levels of VT in Aedes mosquito larvae were also identified. Results All four DENV serotypes (DENV-1 to -4) were identified in the study area. In the early part of the study (December 2015–February 2016), DENV-3 was predominant and from April 2016 to March 2017, DENV-2 became the most predominant type. Four cases of DENV co-infections were noted during the study period in patients. Interestingly, all four DENV serotypes were detected in Aedes albopictus larvae, which was the prominent immature vectorial form identified throughout the study period in the area, showing 9.8% VT of DENV. With the exception of DENV-4, the other three DENV serotypes were identified in Aedes aegypti larvae with a VT of 8.1%. Conclusion Comparatively high rates of VT of DENV was detected in Ae. albopictus and Ae. aegypti larvae. A shift in the predominant DENV serotype with simultaneous circulation of all four DENV serotypes was identified in the study area from December 2015 to March 2017. Graphical Abstract