Transovarial Transmission Of Dengue Virus Research Articles

Study of Dengue Virus Transovarial Transmission in Aedes spp. in Ternate City Using Streptavidin-Biotin-Peroxidase Complex Immunohistochemistry.

Aedes aegypti is the most dominant vector in the transmission of dengue hemorrhagic fever (DHF). In addition to Ae. aegypti, Ae. albopictus is a secondary vector of the dengue virus, and both species are widespread in Indonesia. The dengue virus is transmitted from person to person through the bite of an Aedes spp. The vertical (transovarial) transmission of the dengue virus from infective female mosquitoes to their offspring is one of the means by which the dengue virus maintains its existence in nature. Transovarial dengue virus transmission in Aedes spp. mosquitoes contributes to the spread and maintenance of the dengue epidemic. This study employed a qualitative survey to detect dengue virus transovarial transmission in Ternate using the streptavidin-biotin-peroxidase complex (ISBPC) immunohistochemical test. The ISBPC examination of samples collected from the four subdistricts in Ternate revealed a positive result for transovarial transmission of dengue virus. Four Aedes spp., including two Ae. aegypti females, one Ae. albopictus female, and one Ae. albopictus male, tested positive for transovarial transmission of dengue virus in the district of North Ternate. Four Aedes spp., including three Ae. aegypti females and one Ae. aegypti male, were found to be positive for the transovarial transmission of dengue virus in the Central Ternate district. Seven Aedes spp., including five Ae. aegypti females, one Ae. aegypti male, and one Ae. albopictus female, tested positive for transovarial transmission of the dengue virus in the district of South Ternate city. One Ae. aegypti male showed positive results for transovarial transmission of dengue virus in the Ternate Island District. In this study, the transovarial transmission of the dengue virus occurred in both Aedes spp. female and male mosquitoes. It was demonstrated that Aedes spp. carry the dengue virus in their ovaries and can pass it on to their offspring. As a result, the cycle of passing the dengue virus on to local mosquito populations in the city of Ternate is not going to end just yet.

Detection of Dengue Virus Transovarial Transmission in Dengue Hemorrhagic Fever Endemic Areas

Dengue virus is a group of RNA viruses that are highly pathogenic in humans and spread quickly through the bites of Aedes aegypti and Aedes albopictus mosquitoes, especially in tropical countries. More than half a billion out of 100 countries worldwide are at serious risk of dengue virus infection. Vector surveillance activities with Ovitrap and detection of dengue virus types in Aedes aegypti and Aedes albopictus have never been carried out in Pontianak City. It is important in early alert systems at transmission foci. The purpose of this study was to prove the transovarial transmission of dengue virus in Aedes aegypti and Aedes albopictus mosquitoes with a transovarial transmission index (TTI) in endemic areas in Pontianak City, West Kalimantan. The method used in this research is descriptive observational, viral examination method with immunocytochemistry streptavidin-biotin peroxidase complex (ISBPC) and Polymerase Chain Reaction Transcription Reaction (PCR) aimed at proving the presence of transovarial transmission of dengue virus in the same period. The conclusion in this study is that there is evidence of transovarial transmission of dengue virus in Aedes mosquitoes in endemic areas by 29.3% in Sungai Jawi Dalam sub-district, West Pontianak sub-district, and 39.6% in Batu Layang sub-district, North Pontianak sub-district, mosquito density from the results of the Ovitrap Index measurement (OI) in Batu Layang Village is denser, namely 41.3%, compared to Sungai Jawi Village, which is 38.22% and has succeeded in identifying the type of dengue virus, namely the Dengue virus strain, in the two research locations.

First Record of Natural Transovarial Transmission of Dengue Virus in Aedes albopictus from Cuba.

Transovarial transmission (TOT) of dengue virus (DENV) in Aedes spp. is an important mechanism for DENV maintenance in nature and may be important in initiating outbreaks. The objective of this study was to explore the occurrence of TOT in wild Aedes albopictus populations in Cuba. Mosquito larvae were collected in Cotorro municipality, Havana, Cuba, and identified to species. Fifteen pools of Ae. albopictus each containing 30 larvae were processed for DENV detection by using conventional reverse transcription polymerase chain reaction (RT-PCR) and nested PCR. Four out of 15 pools processed were positive for DENV-3, but no other DENV serotype was detected. This is the first time TOT of DENV detected in Cuban field populations of Ae. albopictus, and this suggests that this species may be an important vector of DENV in Cuba.

Frequency of transovarial transmission of dengue virus in Aedes aegypti mosquitoes in endemic areas of dengue hemorrhagic fever in Ceper District, Klaten Regency, Central Java Province, Indonesia

Klaten Regency is an area in Central Java Province with a high rate of endemic dengue hemorrhagic fever. This study aims to demonstrate a correlation between transovarial transmission and the incidence of dengue haemorrhagic fever in Ceper District, Klaten Regency. Aedes larvae and pupae were collected from January 2019 to March 2019 from various containers, using gamadotic and dipper tools, in Ngawonggo, Kajen, and Meger villages, which have high, medium, and low numbers of dengue cases, respectively. The larvae and pupae obtained were reared into adults. The presence of dengue virus in head squashes of 1-week-old female Ae. aegypti was identified based on an immunocytochemical assay using DSSE10 monoclonal antibody, made at Universitas Gadjah Mada as a primary antibody. The frequency of transovarial transmission of dengue virus (TIR) in Ae. aegypti in the three villages was 35.7%. The highest frequency occurred in Ngawonggo Village, at 40 %, and the lowest in Meger Village, at 28%, while the frequency in Kajen Village was 36.9 %. This study proves that there is a strong correlation (r = 0.99664) between transovarial transmission and the incidence of dengue hemorrhagic fever in Ceper District, Klaten Regency, Central Java.

Pengaruh Lama Penyimpanan Telur terhadap Transovarial Infection Rate Virus DEN-3 pada Nyamuk Aedes aegypti

Transovarial transmission of dengue virus is important phenomenon causes dengue virus survival during inter-epidemic period. The purpose of this study was to analyze effect of egg storage duration on DEN-3 virus Transovarial Infection Rate (TIR) in Aedes aegypti mosquitoes. This was laboratory research with experimental design. Ae. aegypti was infected with the DEN-3 virus per-orally and allowed to undergo its gonotrophic cycle. Eggs stored at room temperature (25±3oC) and relative humidity (70±5%) for 0, 1, 2 and 3 months. Hatched eggs then colonized until become adult mosquito. Sample was taken from colonies at 4, 8, 16 days old. Headsquash of mosquitoes was preparedwith Streptavidin Biotin Peroxidase Complex (SBPC) immunocytochemical method using DSSE 10 monoclonal antibody and detected the presence virus antigen. Transovarial infection rate was determined by counting percentage of positive samples. Data were analyzed by linear regression test. Result of this study showed that in 4, 8, 16 samples showed lowest TIR on 0 month storage (33,33%, 33,33%; 40,00%) and highest TIR observed on 2 month storage (76,67%; 66,67%, 76,67%). Statistical test showed significantly different result (p = 0,013) with α = 0,05 and R2 = 0,476. The duration of egg storage effect on DEN-3 virus TIR in Ae. aegypti mosquito with 47.6% contribution.

THE DETECTION OF DENGUE VIRUS TRANSOVARIAL TRANSMISSION IN Aedesaegypti MOSQUITOES IN PONTIANAK CITY ENDEMIC AREA

The background of this study is that the Dengue Virus is highly pathogenic in humans and spreads rapidly through the bites of Aedes aegypti and Aedes albopictus. more than half a billion of the 100 countries in the world are at serious risk of dengue virus infection. The purpose of this study was to prove the existence of transovarial dengue virus transmission in Ae.aegypti mosquitoes with a transovarial transmission index (TTI) in the Endemis area in Pontianak, West Kalimantan. The method used in this study was observational descriptive with a cross-sectional study, namely to prove the existence of transovarial virdi transport in the same period. The conclusion was proved by the transovarial transmission of dengue virus in Ae.aegypti mosquitoes in Pontianak City, TTI by 30% in Sungai Jawi village, and 40% in Batulayang Village. Virus serotype was found, namely DENV-3.

Detection of transovarial transmission of dengue virus in Aedes spp. (Diptera: Culicidae) from Brontokusuman Village, Yogyakarta, Indonesia

Abstract. Windyaraini DH, Marsifah T, Mustangin Y, Poerwanto SH. 2019. Detection of transovarial transmission of dengue virus in Aedes spp. (Diptera: Culicidae) from Brontokusuman Village, Yogyakarta, Indonesia. Biodiversitas 20: 2061-2067. Dengue Hemorrhagic Fever (DHF) is an infectious vector-borne disease. It is caused by dengue virus infection through the vector of Aedes spp. Dengue virus can be transmitted transovarially from infected female mosquitoes to their eggs. The presence of transovarial transmission allows maintenance of serotypes of dengue virus in nature. Detection of transovarial transmissions can be used to predict disease outbreaks as an effort to control the dengue virus. Dengue control is generally carried out through control of dengue vectors (mosquitoes) with environmental management, the use of chemical agents (insecticides) and biological control. This study was conducted to determine the existence of transovarial (vertical) transmission, factors affecting it and the resistance status of Aedes spp. against cypermethrin insecticide (pyrethroid) in Brontokusuman Village, Mergangsan Sub-district of Yogyakarta, Indonesia. The study was conducted from September 2018 to February 2019 with larvae sampling in 100 houses. The adult Aedes spp. mosquitoes were used as the sample of immunohistochemical methods and bioassay to get the mosquito resistance status against cypermethrin. The transovarial transmission of dengue virus in Aedes spp. from Brontokusuman Village was found in 3 of 100 samples of Aedes spp. mosquitoes, and the TTI value (Transovarial Transmission Index) was 3%. The transovarial transmission is influenced by the density of the infected vectors, the condition of their eggs and the number of dengue cases. The bioassay test results showed that the resistance status of Aedes spp. can be presumed resistance against cypermethrin insecticide.

Transovarial transmission of dengue virus on Aedes aegypti atseveral endemic areas of dengue haemorrhagic fever in Indonesia

Transovarial transmission of dengue virus (DENV) on Aedes aegypti is reported as other mechanisms that played a role in the transmission of dengue hemorrhagic fever (DHF). The aim of research to determine the prevalence of vertical transmission in Ae. aegypti from in several endemic areas of dengue in Indonesia. Sample of mosquitoes were collected from at least 25 locations in West Java and 29 locations outer of West Java (Palembang South Sumatra, Banda Aceh, Lombok West Nusa Tenggara, and Ternate Island) by using ovitraps. Then eggs obtained were hatched in the laboratory to be larvae and become adults. The virus detection from the adult specimens were done by using RT-PCR. The results showed the DENV transovarial transmission in Ae. aegypti in three endemic areas of dengue in West Java (25 isolates), for a while still negatives because the mosquitoes from the area Bogor, Sukabumi and Tasikmalaya examined were not found to contain DENV. Meanwhile, of the 29 isolates in the outer West Java (Palembang South Sumatra, Banda Aceh, Lombok West Nusa Tenggara, and Ternate Island), 8 of themwere detected to have DENV-2. DENV transovarial transmission were not be detectedin West Java because of many factors, such as the nature of DENV was very labile to temperature, humidity and chemical factors, as well as a short period of viremia that affect the success rate of DENV transmission to Ae. aegypti.

Transovarial transmission of DENV in Aedes aegypti in the Amazon basin: a local model of xenomonitoring

BackgroundTransovarial transmission of dengue virus in Aedes spp. mosquitoes is considered an important mechanism for the maintenance of the virus in nature and may be implicated in the occurrence of outbreaks and epidemics of the disease. However, there are few studies involving transovarial transmission and viral vector monitoring as a surveillance tool and control strategy. The present study evaluated transovarial transmission of dengue virus in Aedes aegypti populations as a xenomonitoring strategy in municipalities of the Amazonas state.ResultsAedes sp. eggs (13.164) were collected, with 30% viability of third- and fourth-instar larvae. Transovarial transmission of DENV was detected in all municipalities. The transovarial infection rate (TOR) in the municipalities was 46% of the DENV positive samples. The minimum infection rate (MIR) was 17.7 in the state, varying from 11.4 to 24.1 per 1,000 larvae tested in the respective municipalities. Four DENV serotypes were identified, with DENV I and IV being present in all municipalities investigated. The number of reported dengue fever cases varied during this period.ConclusionsOur results suggest that transovarial transmission may be an important mechanism for the maintenance and spreading of the disease in Amazonas municipalities. Using qRT-PCR, it was possible to identify the four DENV serotypes in larval samples. The methodology used in the present study proved suitable as a DENV xenomonitoring model in immature mosquitoes, contributing to the development of systems for early detection of viral circulation and predictive models for the occurrence of outbreaks and epidemics of this disease.Trial registrationCAAE34025414200005015.

A Comprehensive Entomological, Serological and Molecular Study of 2013 Dengue Outbreak of Swat, Khyber Pakhtunkhwa, Pakistan.

BackgroundAedes aegypti and Aedes albopictus play a fundamental role in transmission of dengue virus to humans. A single infected Aedes mosquito is capable to act as a reservoir/amplifier host for dengue virus and may cause epidemics via horizontal and vertical modes of dengue virus (DENV) transmission. The present and future dengue development can be clarified by understanding the elements which help the dissemination of dengue transmission. The current study deals with molecular surveillance of dengue in addition to ecological and social context of 2013 dengue epidemics in Swat, Pakistan.MethodsHerein, we reported dengue vectors surveillance in domestic and peridomistic containers in public and private places in 7 dengue epidemic-prone sites in District Swat, Pakistan from July to November 2013. Using the Flaviviruses genus-specific reverse transcriptase (RT) semi nested-PCR assay, we screened blood samples (N = 500) of dengue positive patients, 150 adult mosquito pools and 25 larval pools.ResultsThe 34 adult and 7 larval mosquito pools were found positive. The adult positive pools comprised 30 pools of Ae. aegypti and 4 pools of Ae. albopictus, while among the 7 larval pools, 5 pools of Ae. aegypti and 2 pools of Ae. albopictus were positive. The detected putative genomes of dengue virus were of DENV-2 (35% in 14 mosquito pools & 39% in serum) and DENV-3 (65% in 27 mosquito pools & 61% in serum). The higher vector density and dengue transmission rate was recorded in July and August (due to favorable conditions for vector growth). About 37% of Ae. aegpti and 34% Ae. albopictus mosquitoes were collected from stagnant water in drums, followed by drinking water tanks (23% & 26%), tires (20% & 18%) and discarded containers (10% & 6%). Among the surveyed areas, Saidu was heavily affected (26%) by dengue followed by Kanju (20% and Landikas (12%). The maximum infection was observed in the age group of <15 (40%) followed by 15–45 (35%) and >45 (25%) years and was more in males (55.3%) as compare to females (44.7%). The increase in vector mosquito density and the subsequent viral transmission was determined by a complex interplay of ecological, biological and social factors.ConclusionThe suitable environmental conditions and discriminable role of Aedes through trans-ovarial transmission of DENV is indispensable in the recent geographic increase of dengue in Pakistan. Climate change affects the survival and dispersion of vectors as well as the transmission rates of dengue. Control of Aedes mosquitoes (vectors) and elimination of breeding sources must be emphasized and prioritized. Such actions may not only reduce the risk of dengue transmission during epidemics, but also minimize the chances of dengue viruses establishment in new (non endemic) areas of the region.

Rare occurrence of natural transovarial transmission of dengue virus and elimination of infected foci as a possible intervention method

Transovarial transmission of dengue virus has been studied in 33 districts of Rajasthan, India. Small proportion (1.09%) of breeding containers positive for the virus and their elimination has been demonstrated as a possible intervention method of disease control. Dengue virus was isolated from individual mosquitoes employing Indirect Fluorescence Antibody Test and Reverse Transcriptase Polymerase Chain Reaction. Out of 1,30,525 containers examined only 1432(1.09%) showed transovarially transmitted virus activity. Elimination of larvae from all the 1432 virus positive containers resulted in substantial control over prospective transmission of dengue. The study highlights rarity of transovarial transmission under natural conditions and sensitizes whether elimination of vertically infected foci could be used as a new intervention method.

Natural transovarial transmission of dengue virus 4 in Aedes aegypti from Cuiabá, State of Mato Grosso, Brazil.

Dengue is the most prevalent arboviral disease in tropical areas. In Mato Grosso, outbreaks are reported every year, but studies on dengue in this state are scarce. Natural transovarial infection of Aedes aegypti by a flavivirus was investigated in the Jardim Industriário neighborhood of Cuiabá, Mato Grosso. Eggs were collected with ovitraps during the dry, intermediate, and rainy seasons of 2012. After the eggs hatched and the larvae developed to adulthood, mosquitoes (n = 758) were identified and allocated to pools of 1-10 specimens according to the collection location, sex, and climatic period. After RNA extraction, multiplex semi-nested RT-PCR was performed to detect the four dengue virus (DENV) serotypes, yellow fever virus, West Nile virus and Saint Louis encephalitis virus. DENV-4 was the only flavivirus detected, and it was found in 8/50 pools (16.0%). Three of the positive pools contained females, and five contained males. Their nucleotide sequences presented 96-100% similarity with DENV-4 genotype II strains from Manaus, Amazonas. The minimum infection rate was 10.5 per 1000 specimens, and the maximum likelihood estimator of the infection rate was 11.6 (95% confidence interval: 4.8; 23.3). This study provides the first evidence of natural transovarial infection by DENV-4 in Ae. Aegypti in Mato Grosso, suggesting that this type of infection might serve as a mechanism of virus maintenance during interepidemic periods in Cuiabá, a city where dengue epidemics are reported every year. These results emphasize the need for efficient vector population control measures to prevent arbovirus outbreaks in the state.

Natural Transmission of Dengue Virus by Aedes albopictus at Monterrey, Northeastern Mexico

Abstract. Dengue cases occur frequently at Nuevo Leon, Mexico, where Aedes aegypti (L.) and Ae. albopictus (Skuse) are present. Ae. albopictus is considered the second vector of dengue. Because it bites humans outdoors during the day, the mosquito plays an important role in transmission of dengue virus (DENV). However, no previous studies at Nuevo Leon indicated the role of the mosquito outdoors. To assess Ae. albopictus for dengue virus, mosquitoes were collected from April to October 2010 at five localities at Guadalupe and Santiago, Nuevo Leon, (Northeast) Mexico, by using two methods: engine backpack aspirator and ovitraps. In total, 1,836 Ae. albopictus and 833 Ae. aegypti mosquitoes were collected by ovitrap and engine backpack aspirator methods. Groups of mosquitoes were processed by RT-PCR. Examination for DENV infection of mosquitoes showed one positive group of four female Ae. albopictus from an ovitrap. This research provided information that showed transovarial transmission of dengue virus in ...

English

Dengue Fever (DF) is a disease caused by the dengue virus that transmitted by Aedes aegypti (Ae. Aegypti) and Ae. albopictus. Dengue fever is now one of the most important public health problems in Indonesia. Vector control using insecticides is the most important strategy to control the DF. Massal fogging and selective abatisation have implementedd intensively to control Ae. aegypti. However after its a long time implementation, mosquitoes resistance and transovarial transmission have been reported. The aim of the study was to evaluate the susceptibility status of Ae. aegypti to organophosphate and its ability to transovarial transmit degue virus in Kendari City, South East Sulawesi. This was a observational study using cross-sectional design conducted in high endemic areas (Kadia Village) and low endemic areas (Kambu Village). Susceptibility status of Ae. aegypti larvae from F1’s egg generation was evaluated by biochemic assay, whereas the transovarial transmission of dengue virus of adult female Ae. aegypti was evaluated by immunohistochemistry method using head squash preparation. The results showed that the Ae. aegypti larvae resistant was higher in high endemic areas (Kadia Village) (83.33%) than in low endemica areas (Kambu Village) (60.00%). In addition, transovarial transmission index (TTI) of Ae. aegypti dengue virus in the high endemic areas (26%) was significantly higher than in the low endemic areas (12%) (p<0.05). In conclusion, the Ae. aegypti larvae resitance to organophosphate as well as the TTI in high endemic areas is higher than in low endemic area in Kendari, Sout East Sulawesi.

Prospective field study of transovarial dengue-virus transmission by two different forms of Aedes aegypti in an urban area of Bangkok, Thailand

A prospective field study was conducted to determine transovarial dengue-virus transmission in two forms of Aedes aegypti mosquitoes in an urban district of Bangkok, Thailand. Immature Aedes mosquitoes were collected monthly for one year and reared continuously until adulthood in the laboratory. Mosquitoes assayed for dengue virus were processed in pools and their dengue virus infection status was determined by one-step RT-PCR and nested-PCR methods. Of a total 15,457 newly emerged adult Ae. aegypti, 98.2% were dark and 1.8% of the pale form. The results showed that the minimum infection rate (MIR) by transovarial transmission (TOT) of dengue virus during the one-year study ranged between 0 to 24.4/1,000 mosquitoes. Dengue virus TOT increased gradually during the hot summer months, reaching a peak in April-June, while dengue cases peaked in September, a rainy month near the end of the rainy season. Therefore, mosquito infections due to TOT were prevalent four months before a high incidence of human infections. TOT dengue virus infections occurred in both forms of Ae. aegypti. All four dengue serotypes were detected, with DEN-4 predominant, followed by DEN-3, DEN-1, and DEN-2, respectively.

Vírus dengue em larvas de Aedes aegypti e sua dinâmica de infestação, Roraima, Brasil

OBJECTIVE: To detect the presence of dengue virus in larval forms of Aedes aegypti and to associate vector presence with rainfall and incidence of disease. METHODS: Eighteen households were randomly selected for egg collection in a neighborhood of the city of Boa Vista, Roraima, in Northern Brazil. Two oviposition traps were installed per home, and removed after one week. This was repeated on a monthly basis between November 2006 and May 2007. Trap positivity rate and egg density were calculated. Following the eclosion of 1,422 eggs, 44 pools of at least 30 larvae each were formed, which were evaluated for presence of dengue virus using RT-PCR and hemi-nested PCR. Dengue incidence rates in the period were correlated with rainfall rates. The association between these two variables and the number of eggs collected was determined using Pearson correlation. RESULTS: None of the pools tested positive for presence of dengue virus, despite the high incidence of dengue in the neighborhood during the studied period. The density of Ae. aegypti increased with rainfall, but was not correlated with incidence of dengue. CONCLUSIONS: The results suggest that transovarial transmission of dengue virus in mosquitoes occurs at a very low frequency, and therefore virus persistence in urban settings may not depend on such transmission. The mosquito population increased during the rainy season due to increased formation of breeding sites; the lack of correlation with incidence of dengue may be due to underestimation of incidence data during epidemics.

Evidence of Vertical Transmission of Dengue Virus in Two Endemic Localities in the State of Oaxaca, Mexico

Background: Dengue virus is spread in tropical areas of the world and is the causative agent of dengue fever and dengue hemorrhagic fever. It is horizontally transmitted to humans by infected Aedes mosquitoes, but it is also able to be vertically or transovarially transmitted to insect progeny. Objective: In this work, we analyzed the vertical transmission of dengue virus in Aedes aegypti mosquitoes collected in two endemic localities in the state of Oaxaca, Mexico. Methods: The collected larvae were grown in the laboratory and transovarial transmission of dengue virus, either in larvae or newly emerged mosquitoes, was investigated using a semi-nested reverse transcription-polymerase chain reaction method. Results: Although the presence of dengue virus in larvae could not be demonstrated, the viral genome was amplified in 4 out of 43 pools of in-cage born mosquitoes: DEN 2, 3 and 4 serotypes were detected in 2 pools from Tuxtepec and two from Juchitán. Conclusion: The results presented here strongly suggest that dengue virus can be vertically transmitted in mosquitoes from Oaxaca, but more studies will be necessary to analyze the epidemiological impact of this mechanism of transmission.

Transovarial transmission of Dengue virus 1 and 2 as showed by detection in Aedes aegypti larvae

Transovarial transmission of Dengue virus 1 and 2 as showed by detection in Aedes aegypti larvae

Transovarial transmission of dengue 2 virus by Aedes aegypti in nature.

Dengue 2 virus was recovered from three of 123 pools of naturally infected Aedes aegypti larvae (6,200 insects) collected from water containers in Rangoon. The virus was also isolated from two of 76 pools (7,730 mosquitoes) of male Ae. aegypti, collected as larvae and reared in the laboratory to adults. Minimum field infection rates among these two groups of mosquitoes were 1:2,067 and 1:3,865, respectively. Insect pools were inoculated into Toxorhynchites splendens mosquitoes and dengue viral antigen was subsequently detected in headsquash preparations by direct fluorescent antibody technique. Identification of the dengue serotype was done by complement-fixation test. This is the first report of dengue virus isolation from naturally infected mosquito larvae. These findings suggest that transovarial transmission of dengue virus occurs in nature.