Aedes aegypti control in breeding sites through an insecticidal coating with dual effect: Laboratory trials and safety assessment
Cardenas, R. et al. 2024. Med Vet Entomol. 2024;1–14. DOI: 10.1111/mve.12776 Abstract [Shiortened]. Ground water tanks are known to be preferred Aedes aegypti oviposition places providing opportunities for adult and larvae control. A dual-effect insecticidal coating (IC) (alphacypermethrin/ pyriproxyfen) with a slow-release mechanism represents a promising option. Bioassays were designed to determine the mortality and sterilizing effects on gravid mosquitoes exposed to IC. The inhibition of emergence was evaluated in eggs, larvae and pupae exposed in different containers. For the water safety assessment con-centrations of active ingredients were determined by reverse phase high performance liquid chromatography (RP-HPLC) and the health risk was calculated. The IC applied to the interior walls of water-holding containers showed efficacy against Ae. aegypti in terms of high gravid-female mortality (81% at 24 h, p < 0.01), sterilizing effect (inhibition of oviposition by 63%, p < 0.01) and emergence inhibition (100% in eggs, L3 and L4; 97% in pupae). Emergence inhibition was recorded up to 12 months and adult mortality >80%up to 6 months. The use of water stored in treated containers, either for washing or drinking, is not expected to pose a health risk to users. IC applied to domestic water containers has dual and complementary action that reduces Ae. aegypti densities (immature and adult stages).
Note: This approach could be useful in problem underground storm water systems as well as electrical vaults in California.
Larval crowding enhances dengue virus loads in Aedes aegypti, a relationship that might increase transmission in urban environments.
HLC Dutra, et al. PLoS Negl Trop Dis 18(9): e0012482. https://doi.org/10.1371/journal.pntd.0012482
Abstract Background: We sought to understand how ambient temperature and larval densities in the immature aquatic phases determine adult life history traits and dengue virus loads post-infection. We predicted that larval crowding and high temperatures would both lead to smaller mosquitoes that might struggle to invest in an immune response and, hence, would exhibit high viral loads. Methods. We first examined larval densities from urban and rural areas via a meta-analysis. We then used these data to inform a laboratory-based 2×2 design examining the interacting effects of temperature (21 vs. 26˚C) and density (0.2 vs. 0.4 larvae/mL) on adult life history and dengue virus loads. Results. We found that urban areas had an ~8-fold increase in larval densities compared to more rural sites. Crowding led to slower development, smaller mosquitoes, less survival, lower fecundity, and higher viral loads. The higher temperature led to faster development, reduced fecundity, and lower viral loads. The virus-reducing effect of higher temperature rearing was, however, overwhelmed by the impact of larval crowding when both factors were present. Conclusions. These data reveal complex interactions between the environmental effects experienced by immature mosquitoes and adult traits. They especially highlight the importance of crowding with respect to adult viral loads. Together, these data suggest that urban environments might enhance dengue virus loads and, therefore, possibly transmission, a concerning result given the increasing rates of urbanization globally.
Prevalence and Knowledge of Tick-Borne Disease Among Forest Management Workers in Santa Cruz, California
F. Rubino and J. Foley Vector-Borne and Zoonotic Diseases Vol. 24, No. 11
https://doi.org/10.1089/vbz.2024.0012
Abstract Background: This study aimed to compare the exposure histories to ticks and tick-borne pathogens, knowledge, and prevention practices between individuals engaged in fire-related forest management and those participating in recreational activities within Santa Cruz County, CA, in an area of high risk of tick exposure. Methods: Blood samples from 55 forest workers and 58 members of the public were tested for bacterial DNA of and antibodies to Borrelia burgdorferi, Anaplasma phagocytophilum, and Rickettsia species. In addition, a questionnaire was administered to 54 workers and 84 members of the public to identify gaps in knowledge and prevention practices. Results: Although workers had a higher percentage of positive B. burgdorferi antibodies than the public (5.5% compared with 1.7%), the difference was not statistically significant. Conversely, rickettsial antibodies were more prevalent among the public (17.2% versus 3.6% for workers), but specificity to pathogenic bacteria could not be confirmed. No DNA for the three pathogens or antibodies against A. phagocytophilum were detected. Many workers and members of the public reported tick bites (67.4% of participants), with a notable 11% increase among workers in the odds of being bitten for each additional year spent working in forests. Although workers took greater precautions, significant knowledge and practice gaps were identified among both populations, such as an inability to distinguish tick species from common arthropods (mites, spiders, fleas), overestimating the size of ticks, and inappropriate tick-removal techniques. Conclusion: This study underscores the risk of tick-borne diseases faced by fire management workers in Lyme disease–endemic regions. The findings emphasize the necessity for future studies of Lyme disease within this population, and highlight the urgent need for enhanced training programs to minimize these risks.
Evidence of Limited Laboratory Infection of Culex Tarsalis (Diptera: Culicidae) by Usutu Virus
Byers, NM, et al. Evidence of Limited Laboratory Infection of Culex Tarsalis (Diptera: Culicidae) by Usutu Virus. VECTOR-BORNE AND ZOONOTIC DISEASES Volume 00, Number 00, 2024. DOI: 10.1089/vbz.2024.0054
Abstract
Background: Usutu virus (USUV) is an emerging flavivirus, closely related to West Nile virus (WNV), that has spread into Europe from Africa. Since Culex tarsalis Coquillett is an important vector for WNV transmission in the United States, we tested the ability of USUV to replicate in and be transmitted by these mosquitoes. Materials and Methods: USUV was used to infect 3-4 day-old Cx. tarsalis with 5.6 to 7.5 log10 pfu/ml in goose bloodmeals. Saliva, heads, and bodies were collected on day 13 or 14 and analyzed by RT-qPCR for detection for USUV vRNA. Blotting paper punches were also collected daily to assess viral transmissibility. Results: The low and high dose blood meal resulted in 0% and 19.6% of the mosquitoes having established infections, respectively. All of the high dose had a dissemination of USUV RNA to the heads and none of the filter papers had detectable USUV RNA, but five of the capillary saliva collections were positive, representing 45.5% of the infected mosquitoes. Conclusions: Limited infection of Cx. tarsalis was observed when exposed to bloodmeals with greater than 10^7 pfu/mL of USUV, indicating this vector is not likely to have a key role in transmission of the virus.
Note: USUV is in the same Japanese encephalitis complex within the family Flaviviridae as WNV and SLEV. Cx. tarsalis is considered a potential vector of JEV based on vector competence studies [Reeves & Hammon. 1946. J. Exp. Med. 83: 185]. Because USUV causes extensive mortality in blackbirds, it is possible that mosquitoes could be exposed to higher blood meal titers in nature than used in these experiments. Also useful to remember that Cx. tarsalis is less suseptible to WNV than SLEV, and yet WNV is more prevalent because of its higher titers in infected avian hosts.
DENGUE/DHF UPDATE (91): AMERICAS, PAHO/WHO
A ProMED-mail post http://www.promedmail.org ProMED-mail is a program of the International Society for Infectious Diseases http://www.isid.org Date: Mon 7 Oct 2024 Source: PAHO/WHO Epidemiological Alert [edited] https://www.paho.org/en/documents/epidemiological-alert-increase-dengue-cases-americas-region-7-october-2024
Due to the increase in dengue cases reported by countries of the Central American Isthmus and Mexico during 2024 and considering the beginning of the dengue season in South America, the Pan American Health Organization/World Health Organization (PAHO/WHO) encourages Member States to continue their efforts in surveillance, early diagnosis, and timely care of dengue and other arbovirus cases, in order to prevent severe cases and deaths associated with these diseases, and, especially for countries in South America, to review their dengue response plans.
Summary of the situation in the Americas Region
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In the Americas Region, the number of dengue cases recorded during the first half of 2024 exceeded the number of cases historically reported in a year, as compared to all previously recorded years. As of epidemiological week (EW) 36 of 2024, 47 countries and territories in the Americas Region have reported 11 732 921 dengue cases; this number is 2.5 times as high as the number of cases recorded throughout 2023, which was 4 594 823 dengue cases (Figure 1 [for all figures, see source URL]) (1). Between EW 1 and EW 36 of 2024, of the total reported dengue cases, 6 253 754 (53%) were laboratory confirmed. Of this total, 17 610 were characterized as severe dengue (0.15%) and 6650 fatal cases were recorded (case fatality rate of 0.057%) (1). Cases from 6 countries make up 97% of the fatal dengue cases in the Americas Region: Brazil with 5303 (82.4%), Argentina with 408 (6.1%), Peru with 234 (3.5%), Colombia with 131 (1.97%), Paraguay with 121 (1.8%), and Ecuador with 59 (0.88%) fatal dengue cases (1). All 4 serotypes of the dengue virus have been circulating in the Americas Region as of EW 36 of 2024. Brazil, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, and Panama report simultaneous circulation of the 4 serotypes (DENV-1, DENV-2, DENV-3, and DENV-4). Additionally, Argentina, French Guiana, Peru, and Puerto Rico reported simultaneous circulation of DENV-1, DENV-2, and DENV-3 (1). Note: The rest of the posting provides regional data for Mexico, Central and South American countries, all of which have marked increases in cases this year. The medical situation is complicated further by the circulation of all 4 strains of DENV which when contracted serially can lead to serious hemorrhagic disease complications.
NEW WORLD SCREWWORM – PANAMA (02): CATTLE, HUMAN
A ProMED-mail post
ProMED-mail is a program of the International Society for Infectious Diseases
Date: Wed 2 Oct 2024
Source: Prensa Latina [in Spanish, machine trans., edited]
Panama warns of new outbreak of screwworm epidemic
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Panamanian authorities have warned of a new epidemic the country is currently facing with cases of the cattle screwworm which also affects humans.
In statements to Prensa Latina, Carlos Moreno, from the Panama-United States Commission for the Eradication of the Screwworm (COPEG) specified the rise of the plague in mid-2023 was due to the lack of vigilance by both citizens and authorities during the COVID-19 pandemic.
In addition, he explained, the increase in cases, some 27 330 from 2022 to date, was due to other factors such as climate change, movement control, and greater awareness among the population.
The screwworm is not only affecting livestock; humans and other animal species are also being harmed.
In Panama, the Ministry of Health (MINSA) has recorded some 79 cases, according to epidemiologist Damaris Contreras, who called on people not to treat wounds at home but to go to health centers or hospitals.
The screwworm, which is laid by the fly _Cochliomyia hominivorax_, feeds on the living tissue of animals and can be fatal if not treated properly. This fly seeks to lay its eggs in “fresh wounds” of any type of warm-blooded animal. In a single wound, this fly can lay between 150 and 300 eggs, explained Lester Reyes, from Animal Health Epidemiology at the Ministry of Agricultural Development (MIDA). Once the larvae develop, they leave the wound and drop to the ground, where they bury themselves until they reach the pupal stage and thenbecome adult flies. Therefore, when healing these wounds, the maggots must be removed and eliminated immediately, because if they are left alive they turn into flies.
Panama has the only plant for the production of sterile flies which counteract the reproduction of flies laying the eggs of the screwworm. Specifically, the impact is occurring in other countries has led Panama to suspend the distribution of sterile flies, said Reynaldo Vivero, from MIDA, who also explained sterile flies are not being distributed in the country, since they are being sent to other countries to control the outbreak.
See attached for additional postings, comment and information.
—
Communicated by: ProMED
Note: The screwworm fly historically was endemic in the USA and was eradicated by the first SIT program. The fly eventually was pushed south of Mexico, with Panama being the southern border maintained by surveillance and further fly releases. Panama has the only remaining sterile fly production facility. The fly is still endemic in parts of South America. Northern dispersal, if not immediately contained, would require a large scale eradication effort that would be very costly.
DENGUE/DHF UPDATE (87): USA (CALIFORNIA) MORE TRANSMISSION
A ProMED-mail post http://www.promedmail.org
ProMED-mail is a program of the International Society for Infectious Diseases http://www.isid.org
Date: Thu 3 Oct 2024
Source: KOST [edited] https://kost1035.iheart.com/featured/la-local-news/content/2024-10-03-5th-locally-acquired-dengue-case-confirmed-in-la-county/
Los Angeles County health officials Thursday [3 Oct 2024] continue to investigate a 5th locally acquired case of the mosquito-borne illness dengue, this time in a resident of El Monte. The latest patient does not appear to have any connection with the 4 previous reported infections, the county Department of Public Health said Wednesday [2 Oct 2024].
Health officials again stressed that locally acquired cases of dengue are extremely rare in areas where it has not been previously transmitted by mosquitoes. The county previously reported a cluster of 3 infections in the Baldwin Park area, and last week a 4th case was confirmed in a Panorama City resident. Health officials called the spate of local cases “unprecedented.”
None of the local patients had any history of travel to areas where dengue is endemic. In October and November of last year [2023], single locally acquired cases of dengue were confirmed by health officials in Pasadena and Long Beach.
Health officials noted that the symptoms of dengue often mirror those of other viruses, and they urged health-care providers to be “vigilant for dengue fever in patients with acute febrile illness and test for and report such cases of mosquito-borne diseases.”
— Communicated by: ProMED
FROM PROMED [It is interesting to note that the latest patient does not appear to have any connection with the 4 previous reported infections. There is a previously reported cluster of 3 cases in the Baldwin Park area, a single case in Panama City and now the latest one in El Monte. One wonders if there are several other dengue virus infected individuals in these 3 localities that have asymptomatic or very mild infections that have not resulted in medical attention so are not reported.
The above report does not indicate which vector mosquito was likely involved in dengue virus transmission in the 3 localities. As noted in the previously posted comment, the mosquitoes most likely involved are _Aedes aegypti_ or _Aedes albopictus_, both of which have been detected in California over the past 20 years. The preventive measures to avoid ongoing transmission are avoidance of mosquito bites and reduction of the mosquito populations. Mosquito control districts are undoubtedly attempting to control these vector mosquitoes, but that is a difficult task and requires collaboration with local residents to eliminate the water catchments in which these mosquitoes breed around their homes and other buildings.
Note that both _Aedes aegypti_ and _Aedes albopictus_ have been found in Los Angeles County. Which of these transmitted dengue virus to the residents is unknown. Locally acquired dengue virus infections remain extremely rare in California but occurrence of this cluster of cases indicates that local acquisition of dengue virus can occur. – Mod.TY
Note: The juxtaposition of these cases to the primary or imported cases has not been reported. As indicated above, it would seem that potentially other perhaps milder secondary cases have gone unnoticed, although these could still be a source of virus for mosquito infection making a vector control response difficult to focus geographically.
DENGUE/DHF UPDATE (80): USA (CALIFORNIA) LOCALLY ACQUIRED
A ProMED-mail post
Date: Tue 17 Sep 2024 17:05 EDT
Source: Newswise [edited]
Amid southern California’s recent record-breaking heat wave and fast-moving wildfires, public health officials reported the third locally acquired case of dengue fever in the Los Angeles area. Although the events seem unrelated, they actually are connected — and for troubling reasons. Communicated by: ProMED “”This is the third locally acquired dengue case in the Los Angeles, California area this year (2024). This resident was bitten by a dengue virus-infected mosquito, most likely _Aedes aegypti_ or _Aedes albopictus_, both of which have been detected in California over the past 20 years. The question with all these locally acquired infections is: where, when and from whom did the vector take the infectious blood meal? Did that infected individual acquire their dengue infection locally or in a dengue-endemic country and subsequently traveled to Los Angeles County, California while viremic? The risk of ongoing transmission depends on the presence of vector mosquitoes. There are 24 counties in California in which _Aedes aegypti_ and _Aedes albopictus_ have been found over the past 20 years.”
Call for Research Proposals – Coachella Valley Mosquito and Vector Control District
The Coachella Valley Mosquito and Vector Control District is requesting research proposals. This funding opportunity is aimed at improving our Integrated Vector Management Program targeting mosquitoes, red imported fire ants, and flies in the Coachella Valley. Past research projects have included spatial mosquito repellents, virus transmission models, vegetation management in wetlands, biological control of fire ants, and activity of house flies. Because of the unique environment including very high temperatures and low precipitation, projects designed to work with the environmental conditions for surveillance of vectors and vector-borne diseases and projects that tailor control methods to the habitat here are of great interest.
Please see our website for guidelines on proposal submission, interests of the District, and a budget worksheet (you can obtain these at https://www.cvmosquito.org/bids-rfqs-rfps under Research Program FY 2024-2025).
93rd Annual MVCAC Conference – Call for Papers
The theme for the 93rd Annual MVCAC Conference is “Vector Control- A path to a more hospitable world”. The prime topics for consideration are below but please consider submitting even if your paper does not fit into one of these topics. All submissions will be considered. The deadline for submission has been extended to October 18, 2024. Requests made following this date may not be honored and may not appear in the conference program.
- Network System Security Preparedness
- Droplet Deposition/Characterization
- Data Visualization Tools/CalSurv
- Reducing Vector-borne Disease Risk through Messaging Campaigns
- Vertebrate Vector Control
- Vector-borne Disease in California
- WNV, SLE, Zika, Dengue, Malaria
- Hantavirus, Plague, Typhus
- Invasive Aedes Successes & Failures
- Novel Mosquito Control Trials
- Application Equipment
- 3D Printing Symposium
- Mosquitofish Rearing & Transport
- Suspect Pool ID Access and treatment strategies
Questions? Please reach out to Senior Meeting Manager, Rachel Hickerson at rhickerson@amgroup.us.
National Mosquito Control Awareness Week – June 16-22, 2024
National Mosquito Control Awareness Week, observed June 16-22, 2024, educates residents about mosquitoes and how to help prevent the spread of mosquito-transmitted diseases. Join us in spreading the word within your districts by posting our press release and on social media using our content calendar.
- Press Release: California Mosquito Experts Use Innovative Technologies to Control Disease-Spreading Mosquitoes
CDPR has approved WB1 Males for use in California
Following the U.S. Environmental Protection Agency’s registration of Mosquito Mate’s Aedes aegypti WB1 male mosquitoes, the California Department of Pesticide Regulation approved the use of WB1 males in California. For information about plans to use Wolbachia in California please contact Stephen Dobson with Mosquito Mate at sdobson@mosquitomate.com.
May is Lyme Disease Awareness Month
Nymphal Ixodes pacificus are most active in the spring and early summer in California. These tiny ticks pose a greater risk of transmitting Lyme disease.\
Messaging and resources to share in May:
- Social media:
- Lyme disease messaging – CDPH Toolkit or MVCAC PR Google Drive
- Nymphal tick messaging – MVCAC PR Google Drive
- Brochures (available to order):
- Weblinks:
- CDPH Lyme Disease webpage
- CDPH Tick-Borne Disease Prevention webpage
- CDPH Ticks & Tick-Borne Diseases webpage
MVCAC- California Air Resources Board Fact Sheet
Beginning in 2024, the California Air Resources Board (CARB) is implementing new equipment and vehicle regulations to limit the purchase of gasoline powered equipment and promote the use of electric instead. The MVCAC Regulatory Affairs and IVM Committees have created a fact sheet to guide the membership through these changes.
Want insecticide resistance training and testing in your area?
If you would like to collect and test mosquito (Aedes or Culex) samples for insecticide resistance, PacVec provides training and testing services at no charge. Michael Bollinger in Dr. Anton Cornel’s laboratory is leading this activity and is available to discuss testing strategies or to provide on-site training on bottle bioassay testing in your area. We offer three options for testing or training:
1. Partnering with a local agency to host a resistance testing workshop that includes the host agency and neighboring agencies in a single event.
2. Partnering with a local agency to perform mosquito collection and testing with the agency’s staff.
3.Collecting and testing mosquitoes from areas where data are lacking with/without involvement of local agency staff.
Any of the above activities will yield immediate data to guide your control decisions. Involvement of local agency staff is ideal to provide a learning experience. If a single agency would like to host a training that can involve neighboring agencies, that is also very helpful to increase the value of each workshop. If larval bioassays are wanted in addition to CDC bottle bioassays, please let us know that as well.
Contact us as soon as possible at bioassays@pacvec.us to make plans for summer testing and training.
West Nile Virus and Dead Bird Call Center Now Live
The California WNV and Dead Bird Call Center opened for the season on Monday, April 8, 2024. Now through mid-October, members of the public can report a dead bird by calling 1-877-WNV-BIRD (1-877-968-2473). Online reporting continues to be available year-round at: https://westnile.ca.gov/report.
For questions about Call Center operations, please contact: Marie.Cerda@cdph.ca.gov.
As you plan for the upcoming WNV season, CDPH has resources available to assist your communication and outreach efforts:
- WNV & Mosquito Social Media Plan for Local Agencies
- WNV Sample Social Media (including sample messaging for dead bird reporting)
- WNV brochure (available in English and Spanish)
- To order print copies free-of-charge, please email: VBDS@cdph.ca.gov For additional WNV information, including data for 2024, please visit: https://westnile.ca.gov/.
Roaming Dogs, Intense Brown Dog Tick Infestation, and Emerging Rocky Mountain Spotted Fever in Tijuana, Mexico.
Foley J., et al. Am. J. Trop. Med. Hyg., 00(00), 2024, pp. 1–16 doi:10.4269/ajtmh.23-0410
Abstract. A two decades–long epidemic of Rocky Mountain spotted fever in northern Mexico reached the U.S. border city of Tijuana in 2021. Cases were near the city periphery in marginalized areas, some lacking infrastructure such as streets or utilities. We worked in the three census areas where human cases were reported and in 12 additional control Areas Geoestadisticas Basicas. Of 191 examined dogs, 61.8% were tick-infested, with 6-fold increased odds if they were allowed to roam. Although no dogs were Rickettsia polymerase chain reaction–positive, we found one R. rickettsii and 11 Rickettsia massiliae–infected ticks. The rickettsial IgG seroprevalence by immunofluorescence antibody assay was 76.4%, associated with unhealthy body condition, adults, dogs with> 10 ticks, more dogs being seen in the area, and dogs being permitted in the street. Insufficient medical and canine management resources have contributed to a case fatality rate of RMSF that has exceeded 50% in areas. High canine seroprevalence suggests risks to people and dogs; unfortunately, herd immunity is impeded by high turnover in the canine population owing to the birth of puppies and high death rates. Binational One Health workers should monitor disease spread, enact canine population management and tick eradication, and provide prevention, diagnostic, and treatment support.
Note: Abandoning dogs in Mexico by legal and illegal immigrants may only add to this public health issue and perhaps provide some risk for border communities.
Female Aedes aegypti mosquitoes use communal cues to manage population density at breeding sites.
Costa-da-Silva AL, et al.
COMMUNICATIONS BIOLOGY | (2024) 7:143 | https://doi.org/10.1038/s42003-024-05830-5 | www.nature.com/commsbio 1 1234567890
Abstract: Where a female mosquito lays her eggs creates the conditions for reproductive success. Here, we identify a communal behavior among ovipositing female mosquitoes. When choosing equal breeding sites, gravid Aedes aegypti aggregate more often than expected. This aggregation occurs when water contact is restricted and does not require the presence of eggs. Instead, the aggregation is regulated by the number of females present at the breeding site. Using assays with both occupied and empty oviposition sites, we show that the Orco olfactory co-receptor and a carbon dioxide receptor, Gr3, detect the presence of mosquitoes. Orco mutants aggregate more often in empty sites, suggesting attractive olfactory cues influence females to associate with one another. Gr3 mutant females do not prefer either site, suggesting that the CO2 receptor is necessary to evaluate mosquito population density at breeding sites. Further, raising CO2 levels is sufficient to cause wild-type mosquitoes to avoid empty oviposition sites. Our results demonstrate that female mosquitoes can regulate their own population density at breeding sites using attractive and repellent communal cues.
Note: These results are based on a series of well done laboratory choice experiments that begin to tease apart the patterns of oviposition site choice and therefore the distribution of this mosquito in nature — information useful for surveillance and control.
Emerging and lesser-known arboviruses impacting animal and human health
A Faraji1, G Molaei, T Andreadis. J Med Entomol, 60(6), 2023, 1139–1141.
https://doi.org/10.1093/jme/tjad140.
In an effort to address problems surrounding emerging vector-borne pathogens, we have dedicated a series of Forum Articles for a special issue of the Journal of Medical Entomology titled “Emerging and Lesser-Known Arboviruses Impacting Animal and Human Health”. It is our hope that this series will further contribute to our understanding of these lesser-known arboviruses for the benefit of vector control personnel, clinicians, and public health stewards within a One Health approach. This issue will encompass arboviruses transmitted by biting midges (Diptera: Ceratopogonidae), mosquitoes (Diptera: Culicidae), and hard ticks (Ixodida: Ixodidae).
Note: Included within this series are papers on Cache Valley, Jamestown Canyon and Snow shoe hare, viruses thought to occur in California [see Reeves’ Monograph published by the MVCAC], but not included within current molecular surveillance diagnostics.
The mosquito knows no borders: Regional challenges for global confrontation in the dengue battle
Barcante JMP, Cherem J (2024)
https://doi.org/10.1371/journal.pntd.0011830
Note: Paper reviews the increasing international public health importance of dengue and calls for improved prevention focusing on vector control. The remarkable increase in cases throughout Central and South America undoubtedly will increase the risk of cases imported into California. The expanding distribution and abundance of Aedes aegypti concurrently will increase the risk of local transmission.
Do it yourself: 3D-printed miniature CDC trap for adult mosquito (Diptera: Culicidae) surveillance
Bibbs CS, Reissen N, Dewsnup MA, Sorensen RB, Faraji A, White GS (2024)
https://doi.org/10.1371/journal.pntd.0011899
Abstract: 3D printing could improve the accessibility of the CDC trap by eliminating some of the supply chain variables. We present here several trials with the Salt Lake City (SLC) trap, a three-dimensional (3D) printed trap design. No statistically significant differences were found when comparing CO2 line height(above vs. below fan), battery types (sealed lead acid vs. USB battery pack), and trap body collection shape (funnel body vs. simple/straight body). The SLC trap was compared directly to a commercial equivalent, the Clarke ABC trap, with comparative assessment on species diversity and abundance and found to be statistically equivalent on all metrics. Our final design is presented here with the publicly published stereolithography (STL) files and a detailed outline of the transport container system.
Note: This trap design was presented at the Annual MVCAC conference and is cited here for reference.
Response to An Outbreak of Locally Transmitted Dengue in Key Largo, FL
The Florida Keys Mosquito Control District. J Am Mosq Control Assoc., 39 (4), 2023, pp. 251–257.
Doi: https://doi.org/10.2987/23-7145
ABSTRACT: Seventy-two cases of locally acquired dengue were contracted by residents and visitors of Key Largo, FL, in 2020. The primary vector, Aedes aegypti, has been a large focus of the Florida Keys Mosquito Control District’s (FKMCD) control measures for over a decade. This paper recounts the 2020 outbreak of DENV in Key Largo, FL, and the FKMCD’s Ae. aegypti operational response. The overall House Index (13.43%) during the outbreak was considered high (>5%) risk for local transmission. Larval habitat characterized from property inspections was similar to previous larval and pupal habitat studies. Adult surveillance of the active dengue transmission area provided 3 positive pools out of 1,518 mosquitoes tested resulting in a minimum infection rate of 1.976. Increased personnel response with long-term larvicide formulations and increased aerial, truck, and handheld ultra-low-volume adulticide control measures quickly reduced the Ae. aegypti surveillance numbers below the action threshold. No active cases of dengue have been reported since October 2020.
Note: This article provides a case study of one district’s response to a local dengue outbreak. Here, two initial cases were reported on 3 Mar 2020 but subsequent suspect cases were not recognized until 17 Jun after considerable transmission. Two cases that occurred in Jan 2020 were not reported until late 2021. This cascade of events clearly shows the importance of case surveillance and reporting and fits well with our conference discussions as districts review existing response plans following California’s first two cases of locally transmitted dengue.
Tick Resources Reminder
Adult Ixodes pacificus ticks are most active in California from fall through early spring. Now is a great time to encourage repellent use and tick checks for tick bite prevention.
For sample messaging and educational materials about ticks and tick bite prevention, please visit go.cdph.ca.gov/ticks and the following resources:
- CDPH Tick-Borne Disease Prevention webpage (now available in Spanish)
- Sample social media messages and graphics
- CDPH Common Ticks in California ID card (
English version now updated; to order copies, please email VBDS@cdph.ca.gov)
2024 Sentinel Chicken Order Forms Available Now!
Chickens are being supplied by Gemperle Family Farms in Turlock, CA
Please return order form by March 1, 2024 Via email or fax to 916-444-7462
Northern and Southern Region
Pick-up date: Mid-April. Specific date, and location TBD (Turlock/Hilmar area)
The address for the farm will be provided as soon as we have it.
Questions: please email or call R’Mani White in Membership at rwhite@amgroup.us or (916) 440-0826 ext 125.
Epidemiological Update — Western Equine Encephalitis in the Region of the Americas
January 10, 2024
Summary of the situation: On 19 Dec 2023, the Pan American Health Organization/World Health Organization (PAHO/WHO) warned about the risk to human health associated with the circulation of the western equine encephalitis virus (WEE). From that date until 9 Jan 2024, 374 additional outbreaks (equine outbreak: occurrence of one or more cases of WEE in equines) in animals were reported (338 in Argentina and 36 in Uruguay) and 21 human cases, all of them in Argentina. Note: Human cases of WEEV have been absent from Argentina for more than 2 decades, similar to the long time absence of WEEV from California. We should remember that the SLEV strains now circulating in the SW USA [including California] were most closely aligned with strains previously isolated from Argentina, perhaps establishing a route/corridor for introduction by migrant birds? Testing Culex mosquitoes by triplex during 2024 would again seem prudent.
Help Support the 2024 WNV Call Center
The WNV Call Center needs YOUR help meeting their 2024 funding goal!
The West Nile Virus Call Center helps keep California safe from disease outbreaks by allowing the public to report dead birds on their area.
If other agencies are interested in contributing, please email Vicki.Kramer@cdph.ca.gov
Surveillance of Flea-Borne Typhus in California, 2011–2019
Yomogida K, Kjemtrup A, et al. Am. J. Trop. Med. Hyg., 110(1), 2024, pp. 142–149.
doi:10.4269/ajtmh.23-0272.
Abstract. Flea-borne typhus (FBT) is an acute febrile disease in humans caused by the bacteria Rickettsia typhi. In California, healthcare providers and testing laboratories are mandated to report to their respective local public health jurisdictions whenever R. typhi or antibodies reactive to R. typhi are detected in a patient. This study characterized the epidemiology of 881 flea-borne typhus cases in California from 2011 to 2019, with most cases reported among residents of Los Angeles and Orange Counties (97%). Demographics, animal exposures, and clinical courses for case patients were summarized. Additionally, spatiotemporal cluster analyses pointed to five areas in southern California with persistent FBT transmission.
Note: Additional detailed information has been published in the Proceedings of the MVCAC Annual Conference.
Call for Volunteers
Are you attending MVCAC 2024 in Monterey, CA?!?
We are hosting an AMCA YPs booth at the upcoming MVCAC annual meeting in Monterey, CA! To make this event a success, we are seeking enthusiastic volunteers to assist with the YPs booth and various conference logistics. If you are attending, volunteer at our AMCA YPs booth! Connect and engage with your fellow California YP peers and seasoned professionals. If you’re eager to be a part of this dynamic experience, please complete the volunteer form: bit.ly/24MVCAC_YPsBooth
CalSurv Seeking Examples of Visualizations and Data Summaries
The CalSurv development team is seeking examples of visualizations and data summaries your agency includes in reports. If you’re willing to submit examples of reports that are useful to you, we’ll do our best to incorporate some of the examples in our workshops and resources. Please upload any example reports here.
If you missed our October training on creating your own reports in R using the new VectorSurv API, it’s not too late! You can check out the video on our YouTube channel. To get periodic updates from our team, sign up for our newsletter here.
Large-scalereleases and establishment of wMel Wolbachia in Aedes aegypti mosquitoes throughout the Cities of Bello, Medellı´n and Itagu¨ı´, Colombia. PLoS Negl
Velez ID, Uribe A, Barajas J, Uribe S, A´ ngel S, Suaza-Vasco JD, et al. (2023)
Trop Dis 17(11): e0011642.
https://doi.org/10.1371/journal.pntd.0011642
The introduction of the naturally occurring wMel Wolbachia strain into Aedes aegypti mosquitoes has been shown to reduce the ability of the mosquitoes to transmit dengue and other viruses. Following engagement with communities to gain acceptance and support, a series of large-scale releases of Ae. aegypti mosquitoes that contained wMel Wolbachia, were undertaken across the cities of Bello, Medellı´n and Itagu¨ı´ in Colombia. These releases were undertaken under operational conditions with the aim of rapidly scaling the intervention in response to the Zika virus crisis. Mosquito populations were monitored during and after releases to determine the levels of Wolbachia and whether it persisted in the local mosquitoes. Wolbachia was found to be stable and established at consistent levels in local mosquito populations in the majority of areas. On-going monitoring in these areas will determine whether Wolbachia persists and also whether it establishes at a high level in the remaining areas. This intervention forms the basis of an epidemiological study to assess the impact of operational deployment of wMel Wolbachia on the reduction of the incidence of notified dengue cases and virologically-confirmed dengue.
Note: This important study shows the establishment of the wMel Wolbachia and the companion paper shows the reduction of dengue in the treated cities. However, this method does not reduce the biting pressure of Aedes aegypti and insecticide applications would be counter intuitive to this public health response.
Fitness costs in the presence and absence of insecticide use explains abundance of two common Aedes aegypti kdr resistance alleles found in the Americas.
Silva JJ, Fisher CR, Dressel AE, Scott JG (2023)
PLoS Negl Trop Dis 17(11): e0011741
https://doi.org/10.1371/journal.pntd.0011741
Resistance to widely used pyrethroid insecticides can occur by mutations in the voltage gated sodium channel (Vgsc) and alleles with these mutations are collectively known as knockdown resistance (kdr). The frequency of resistance alleles is driven by selection with pyrethroid insecticides, but kdr alleles decrease in frequency in the absence of insecticide. The relative fitness of different kdr alleles to each other is largely unknown. We show through cage experiments that the 1534C allele is favored in the absence of pyrethroid applications, but that the 410L+1016I+1534C allele is favored when deltamethrin selection occurs. These results help to explain the relative frequency of these alleles that have been detected in field collections.
Q&A: New York Times Reporter Reflects on Global Malaria Fight
November 28, 2023
New York Times Global Health Reporter Stephanie Nolen traveled to five countries in Africa and Latin America to crack the code on what’s being done to control mosquito-borne diseases. Here’s what she found.
Special Collection: Emerging and Lesser-Known Arboviruses Impacting Animal and Human Health: Emerging and lesser-known arboviruses impacting animal and human health.
A Faraji, G Molaei, T Andreadis. Special Collection: Emerging and Lesser-Known Arboviruses Impacting Animal and Human Health: Emerging and lesser-known arboviruses impacting animal and human health. J Medical Entomol, 60(6), 2023, 1139–1141.
https://doi.org/10.1093/jme/tjad140
This paper is the introduction to Special Collection of 10 papers on the epidemiology and ecology of emerging and lesser-known viruses of public and veterinary importance within the United States. Included within the series are papers on orbiviruses transmitted by Culicoides, lesser known viruses transmitted by mosquitoes including Cache Valley, Everglades, Jamestown Canyon, and LaCrosse, and recently discovered viruses transmitted by ticks including Bourbon, Heartland, Colorado tick fever, and Powassan.
FDA Approves First Vaccine Against Mosquito-Borne Virus Chikungunya
November 10, 2023
From The Washington Post
The Food and Drug Administration has approved the world’s first vaccine to prevent chikungunya, a mosquito-borne illness that can cause debilitating joint pain for months to years.
Aedes Aegypti Oviposition-Sites Choice Under Semi-Field Conditions
David,M.R.,Maciel-de-Freitas,R., Petersen,M.T.,Bray,D.,Hawkes,F.M.,Fernández-Grandon, G.M.etal.(2023)
Aedes aegypti oviposition-sites choice under semi-field conditions. Medical and Veterinary Entomology, 37(4),683–692.
Available from:https://doi.org/10.1111/mve.12670
Aedes aegypti in Brazil were offered a variety of oviposition containers within a semi-field cage. Gravid females preferred to oviposit close to the ground and in open water containers with organic compounds from plant watering. Domestic large artificial containers containing tap water received significantly fewer eggs, except for car tires, which received as many eggs as potted plants. Visual (potted plant shape) and olfactory clues (odor of the plant or from water containing organic matter) were equally attractive separately as they were together. These data may be useful in surveillance and control operations searching for larval sources.
First locally acquired case of dengue virus discovered in Pasadena
October 20, 2023
Public health officials confirmed Friday the first locally acquired case of dengue virus in a Pasadena resident. This case is the first in California that is not associated with travel, according to Manuel Carmona, acting director of Public Health for the City of Pasadena.
Rodent-targeted approaches to reduce acarological risk of human exposure to pathogen-infected Ixodes ticks.
Lars Eisen
Ticks Tick Borne Dis. 2023 Mar;14(2):102119, https://doi.org/10.1016/j.ttbdis.2023.102119
Condensed abstract: In the United States, rodents serve as important hosts of medically important Ixodes ticks, including Ixodes scapularis and Ixodes pacificus, as well as reservoirs for human pathogens, including Anaplasma phagocytophilum, Borrelia burgdorferi sensu stricto (s.s.), and Babesia microti. Over the last four decades, different methods to disrupt enzootic transmission of these pathogens between tick vectors and rodent reservoirs have been developed and evaluated. These techniques include the application of topical acaricides, antibiotics, or a vaccine against Bo. burgdorferi s.s., delivered orally via rodent food baits. This review outlines the general benefits and drawbacks of rodent-targeted tick and pathogen control methods, and then describes the empirical evidence for different approaches to impact enzootic pathogen transmission and acarological risk of human exposure to pathogen-infected Ixodes ticks. Note: This review paper describes various rodent-targeted tick management techniques, summarizing results of experiments and compiling the benefits and drawbacks.
MVCAC’s Response to Dengue Case in Pasadena
In response to the locally acquired dengue case recently reported in Pasadena, MVCAC drafted a statement to assist with your outreach efforts and if you receive questions from residents and stakeholders.
Podcast Episode: The Mosquitoes Are Winning
From The Daily
For decades, the world seemed to be winning the war against mosquitoes and tamping down the deadly diseases they carried. But in the past few years, progress has not only stalled, it has reversed. Stephanie Nolen, who covers global health for The Times, explains how the mosquito has once again gained the upper hand in the fight.
CA West Nile Virus & Dead Bird Call Center closes for the season on October 13, 2023
This season, the California Department of Public Health received over 5,900 dead bird reports to the CA West Nile Virus & Dead Bird Call Center (1-877-WNV-BIRD) and website. Over 1,700 dead birds were collected for testing, with 773 birds testing positive for West Nile virus (WNV). On October 13, the Call Center will transition to internet-only reporting at https://westnile.ca.gov/. WNV testing is limited in the fall and winter as WNV activity decreases, but dead bird reports are appreciated all year round.
Dengue Will ‘Take Off’ in Southern Europe, US, Africa This Decade, WHO Scientist Says
October 9, 2023
From MedScape
Dengue fever will become a major threat in the southern United States, southern Europe and new parts of Africa this decade, the WHO’s chief scientist said, as warmer temperatures create the conditions for the mosquitoes carrying the infection to spread.
AMCA Research Fund Day of Contributing: October 10, 2023
Date: Tuesday, October 10th, 2023
What Is It? It’s a day for everyone in the AMCA community to come together and support mosquito control research. Your contribution, no matter the amount, can make a significant impact.
How Can You Participate?
- Mark Your Calendar: Set a reminder for October 10th.
- Donate: We’ll provide a donation link on the day.
- Spread the Word: Share our social media posts to encourage your community to contribute too.
Why Do We Need Your Support? Your involvement can help us advance research, nurture young scientists, and protect public health. We are hoping our community can gather together to help us support one additional project each year!
Convergent Trends and Spatiotemporal Patterns of Aedes-Borne Arboviruses in Mexico and Central America
Bernardo Gutierrez ,Darlan da Silva Candido,Sumali Bajaj,Abril Paulina Rodriguez Maldonado,Fabiola Garces Ayala,María de la Luz Torre Rodriguez,Adnan Araiza Rodriguez,Claudia Wong Arámbula,Ernesto Ramírez González,Irma López Martínez,José Alberto Díaz-Quiñónez,Mauricio Vázquez Pichardo,Sarah C. Hill, [ … ],Marina Escalera-Zamudio [ view all ]
Published: Plos Neglected Tropical Diseases, September 6, 2023
https://doi.org/10.1371/journal.pntd.0011169
Results indicate that CHIKV, DENV-1 and DENV-2 in Mexico share evolutionary and epidemiological trajectories. The southwest region of the country was determined to be the most likely location for viral introductions from abroad, with a subsequent spread into the Pacific coast towards the north of Mexico. Virus diffusion patterns observed across the country are likely driven by multiple factors, including mobility linked to human migration from Central towards North America. Considering Mexico’s geographic positioning displaying a high human mobility across borders, our results prompt the need to better understand the role of anthropogenic factors in the transmission dynamics of Aedes-borne arboviruses, particularly linked to land-based human migration.
Direct Mosquito Feedings on Dengue-2 Virus-Infected People Reveal Dynamics of Human Infectiousness
Louis Lambrechts, Robert C. Reiner et.al.
Plos Neglected Tropical Diseases Sept 2023
https://doi.org/10.1371/journal.pntd.0011593
This study in Iquitos, Peru, showed that dengue patients with mild disease were most infectious to Aedes aegypti mosquitoes 2 d after the onset of symptoms and that these mosquitoes were able to transmit their infection 7 – 16 d after blood feeding. This empirical study provided a timeline for when secondary dengue cases could be expected following the onset of symptoms in an imported dengue case, thereby providing a timeline for preventive control operations.
Article Series: Mosquitoes Are a Growing Public Health Threat, Reversing Years of Progress
September 29, 2023
From New York Times
Climate change and the rapid evolution of the insect have helped drive up malaria deaths and brought dengue and other mosquito-borne viruses to places that never had to worry about them.
The late-summer itch: Ankle-biting mosquitoes are in extra full force in L.A. Why?
From LA Times
September 21, 2023
When you think “so L.A.,” Erewhon smoothies, Barbie-pink sunsets and baristas with IMDB credits might come to mind. Now you can add mosquitoes to the list.
CA Endures Worst Mosquito Season In Years. When Will It End?
From Patch
September 16, 2023
As the blood-sucking ankle-biters take bite out of the Golden State, human West Nile Virus cases are spiking.
First West Nile Virus Death Reported in LA County
September 7. 2023
From the County of Los Angeles Public Health
First death of 2023 reinforces need for all residents to take precautions against mosquitoes
The biting rate of Aedes aegypti and its variability: A systematic review(1970–2022).
:ZahidMH, VanWykH, MorrisonAC, ColomaJ, LeeGO, CevallosV, etal.(2023)
https://doi.org/10.1371/journal.pntd.0010831
Author summary: Half of the world’s population is now at risk of dengue infection, which transmits to humans mostly through the bite of an infected female Aedes aegypti mosquito. Disease transmission models have played an important role in understanding the dynamics of dengue transmission and helping to develop control measures. The mosquito biting rate is one of the central parameters used in these models. Mosquito biting rates used in existing works are taken from a variety of studies, each with its strengths and limitations. To understand how existing study designs are used to estimate biting rate and how these estimates may vary over time, space, and environmental factors, we perform a systematic review of biting rate studies. We identify three study designs (human landing catch, marked-release-recapture, and histological) that play an important role in estimating per mosquito biting rates and capturing variability across a number of environmental factors. In particular, human landing catch studies can capture the variability of biting rates and marked-released-recapture studies along with histological studies can quantify the multiple feeding that occurs between ovipositions. Transmission modeling studies should be more informed by the biology of mosquito behavior. By understanding the biology of blood-feeding and context-specific factors, we can arrive at more informed per mosquito biting rate estimates for site-specific transmission model analysis.
[Submitted by the Vector and Vector-Borne Disease Committee]
West Nile virus is a growing threat this summer in California. What you need to know
August 30, 2023
From Los Angeles Times
West Nile virus infections are on the rise this year in California after a particularly wet winter led to more mosquito reproduction, according to health experts.