Global & Disaster Medicine

Archive for the ‘Dengue’ Category

AGS-v: An investigational vaccine that triggers an immune response to mosquito saliva rather than to a specific virus or parasite carried by mosquitoes

NIAID

The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), has launched a Phase 1 clinical trial to test an investigational vaccine intended to provide broad protection against a range of mosquito-transmitted diseases, such as Zika, malaria, West Nile fever and dengue fever, and to hinder the ability of mosquitoes to transmit such infections. The study, which is being conducted at the NIH Clinical Center in Bethesda, Maryland, will examine the experimental vaccine’s safety and ability to generate an immune response.

Mosquito vaccine trial partipant recieves injection

The investigational vaccine, called AGS-v, was developed by the London-based pharmaceutical company SEEK, which has since formed a joint venture with hVIVO in London. The consulting group Halloran has provided regulatory advice to both companies.

Unlike other vaccines targeting specific mosquito-borne diseases, the AGS-v candidate is designed to trigger an immune response to mosquito saliva rather than to a specific virus or parasite carried by mosquitoes. The test vaccine contains four synthetic proteins from mosquito salivary glands. The proteins are designed to induce antibodies in a vaccinated individual and to cause a modified allergic response that can prevent infection when a person is bitten by a disease-carrying mosquito.

“Mosquitoes cause more human disease and death than any other animal,” said NIAID Director Anthony S. Fauci, M.D. “A single vaccine capable of protecting against the scourge of mosquito-borne diseases is a novel concept that, if proven successful, would be a monumental public health advance.”

Led by Matthew J. Memoli, M.D., director of the Clinical Studies Unit in NIAID’s Laboratory of Infectious Diseases, the clinical trial is expected to enroll up to 60 healthy adults ages 18 to 50 years. Participants will be randomly assigned to receive one of three vaccine regimens. The first group will receive two injections of the AGS-v vaccine, 21 days apart. The second group will receive two injections of AGS-v combined with an adjuvant, 21 days apart. The adjuvant is an oil and water mixture commonly added to vaccines to enhance immune responses. The third group will receive two placebo injections of sterile water 21 days apart. Neither the study investigators nor the participants will know who is assigned to each group.

Participants will be asked to return to the clinic twice between vaccinations and twice after the second vaccination to undergo a physical exam and to provide blood samples. Study investigators will examine the blood samples to measure levels of antibodies triggered by vaccination.

Each participant also will return to the Clinical Center approximately 21 days after completing the vaccination schedule to undergo a controlled exposure to biting mosquitoes. The mosquitoes will not be carrying viruses or parasites, so the participants are not at risk of becoming infected with a mosquito-borne disease. Five to 10 female Aedes aegypti mosquitoes from the insectary in NIAID’s Laboratory of Malaria and Vector Research will be put in a feeding device that will be placed on each participant’s arm for 20 minutes. The mosquitoes will bite the participants’ arms through the netting on the feeding devices.

Afterward, investigators will take blood samples from each participant at various time points to see if participants experience a modified response to the mosquito bites as a result of AGS-v vaccination.

Investigators also will examine the mosquitoes after the feeding to assess any changes to their life cycle. Scientists suspect that the mosquitoes who take a blood meal from ASG-v-vaccinated participants may have altered behavior that could lead to early death or a reduced ability to reproduce. This would indicate that the experimental vaccine could also hinder disease transmission by controlling the mosquito population.

All participants will be asked to return to the clinic for follow-up visits every 60 days for five months following the mosquito feeding. A final clinic visit to assess long-term safety will take place approximately 10 months after the mosquito feeding. Throughout the trial, an independent Data and Safety Monitoring Board will review study data to evaluate participant safety and the overall conduct of the study. A medical monitor from NIAID’s Office of Clinical Research Policy and Regulatory Operations will also perform routine safety assessments.

The study is expected to be completed by summer 2018. For more information about the trial, see ClinicalTrials.gov using the trial identifier NCT03055000 (link is external).


Mosquito-disseminated pyriproxyfen (PPF), a potent juvenile-killing insecticide, has potential to block mosquito-borne virus transmission citywide

PLOS

Abad-Franch F, Zamora-Perea E, Luz SLB (2017) Mosquito-Disseminated Insecticide for Citywide Vector Control and Its Potential to Block Arbovirus Epidemics: Entomological Observations and Modeling Results from Amazonian Brazil. PLoS Med 14(1): e1002213. doi:10.1371/journal.pmed.1002213

Aedes-aegypti_1

 

 


In 2013 there were a total of 58.40 million symptomatic dengue virus infections including 13 586 fatal cases, and that the total annual global cost of dengue illness was US$8·9 billion.

The Lancet

Image: Lab Confirmed cases of Dengue in South America

Image: Dengue in the world

 

 


Group from Argentina developes a plastic ovitrap, a small cup made from low-density polyethylene that has been infused with pyriproxyfen to knock off Aedes mosquitoes

Aedes Traps

 

Biological and Chemical Characterization of a New Larvicide Ovitrap Made of Plastic With Pyriproxyfen Incorporated for Aedes aegypti (Diptera: Culicidae) Control

Brazil: Zika isn’t the only emergency. 2 other mosquito-borne viruses are spiking: Dengue and CHIKV. Meanwhile, the country is going through a massive economic and political crisis as well, facing one of the worst recessions in its history.

NPR

Recife:  “….New cases of microcephaly are dramatically down. Last November, Recife registered 125 cases. But since the beginning of this year, the numbers have hovered around 25 a month……[T]he decline was expected: Women giving birth this spring would have become pregnant during the cooler winter period when there were fewer mosquitoes around to transmit Zika……”


Fighting the Aedes mosquito

Graphic: Mosquito prevention starts with you


Kids with Dengue

NEJM

Symptomatic Dengue in Children in 10 Asian and Latin American Countries

Maïna L’Azou, M.Sc., Annick Moureau, M.Sc., Elsa Sarti, Ph.D., Joshua Nealon, M.Sc., Betzana Zambrano, M.D., T. Anh Wartel, M.D., Luis Villar, M.D., Maria R.Z. Capeding, M.D., and R. Leon Ochiai, Ph.D., for the CYD14 and CYD15 Primary Study Groups*

N Engl J Med 2016; 374:1155-1166

March 24, 2016

DOI: 10.1056/NEJMoa1503877

“…..The incidence of dengue hemorrhagic fever was less than 0.3 episodes per 100 person-years in each cohort. The percentage of VCD episodes requiring hospitalization was 19.1% in the Asian cohort and 11.1% in the Latin American cohort. In comparable age groups (9 to 12 years and 13 to 16 years), the burden of dengue was higher in Asia than in Latin America……”


Zika is just one of a growing number of continent-jumping diseases carried by mosquitoes and threatening swathes of humanity.

Reuters

 

global_epc_2015294_front

 

 


The Aedes mosquitoes that transmit the virus on Puerto Rico have developed resistance to permethrin.

STAT

 

 


Latest Research: Evidence suggests that symptomatic dengue during pregnancy might be associated with fetal adverse outcomes.

Lancet

**  Preterm birth and low birth weight were the most common adverse outcomes in mothers who contracted dengue.

 

 


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