VECTOR BORNE
DISEASES
Why are we here today?
• Understanding vectors
• Type of vectors
• Vector borne diseases
• Symptoms
• Risk assessment
• Risk mitigation
This Photo by Unknown author is licensed under CC BY-ND.
Source: Elizabeth Hitchcock
Nasalis larvatus
&
Plasmodium knowlesi
Source: https://doi.org/10.1038/
s41598-018-28457-z
What should we be aware of?
What are vectors?
Diseases associated with vectors.
Symptoms.
Risk assessment.
Risk mitigation.
Current trends in research & development
400,000
Vectors: no longer taken for granted!
Breaking the chain of infection
CONTAINMENT!
Perturbation of natural equilibria
Climate change
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Resurgence of Malaria in North America as infections surge in Central America.
Indicators: Data from Goa
Vector-borne disease Confirmed cases
MALARIA 200
DENGUE 217
JAPANESE ENCEPHALITIS 1
CHIKUNGUNYA 89
Data Source:http://dhsgoa.gov.in/documents/MonthlyPerformace.pdf (September 2019)
Mosquito borne
diseases
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Anopheles stephensi
Photo credits: Jim Gathany, Center for Disease Control and Prevention, Publich Health Image Library
Cases: 229 Million
Reported deaths: 406,000
Source: World Health Organization (2019)
67% Children (<5 years)
Evidence of malaria in Egyptian mummies.
This Photo by Unknown author is licensed under CC BY-SA.
Citation: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2600410/
Charles Louis
Alphonse Laveran
(1845 – 1922)
1880
Discovered the unicellular,
eukaryotic protozoan which is the causative agent of Malaria.
Plasmodium
• Plasmodium falciparum
• Plasmodium malariae
• Plasmodium vivax
• Plasmodium ovale
• Plasmodium knowlesi
Content Providers: CDC/Dr. Mae Melvin
Understanding the life cycle
8 to 10 days
This Photo by Unknown author is licensed under CC BY-SA.
Source: https://www.sciencedirect.com/science/article/pii/S1471492218302484
Gametocyte commitment in the human host
Citation: https://www.intechopen.com/books/current-topics-in-malaria/the-biology-of-malaria-gametocytes
Citation: https://www.intechopen.com/books/current-topics-in-malaria/the-biology-of-malaria-gametocytes
Symptoms
• Acute febrile illness
• Incubation time: 10 to 15 days after exposure
• Fever and chills
• Severe anemia in children
• Cerebral malaria
• Asymptomatic carriers
• MUST BE TREATED WITHIN 24 HOURS OF THE ONSET OF SYMPTOMS!
Diagnosis
Polymerase chain reaction which targets specific loci in the 5 species of Plasmodium.
Detection using fluorescent antibodies.
Dawn & dusk
Mosquitoes are most active during these two periods of the day.
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Attractants
• Carbon dioxide
• Floral perfumes
• Sweat
• R-Octenol
• Blue & green lights
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Prevention
&
treatment
Do not self-medicate.
Drug resistance due to indiscriminate use.
Atovaquone/Proguanil (Malarone) Chloroquine
Doxycycline Primaquine
Sulfadoxine-pyrimethamine
Chloroquine
Image Source (Credits): Benjah-bmm27
Discovered by Johann Andersag Long-term toxicity to the host.
Chloroquine resistance.
Artemisinin
Source: Artemisia annua
Tu Youyou
Image credits (Source):BromothymolAMB Image credits: Bengt Nyman
Vaccines
• Currently no approved vaccine.
• High level of antigenic variation.
• Experimental vaccine: GlaxoSmithKline Biologicals’
RTS,S/AS01
• Whole Sporozoite (PfSPZ) Vaccines: Sanaria ®
• Vaccines and sub-Saharan Africa.
Aedes aegyptii
Dengue
Flavivirus (+ssRNA)
Vector: Aedes aegypti and Ae.
albopictus
Serotypes: Four (4)
Infections: 100 to 400 million / year
Treatment: based on case.
Image source & Credits: Girish Khera, Animations (http://www.scientificanimations.com/)
Symptoms
• Symptomatic cases: 1 in 4
• Severe dengue: requires immediate medical attention.
• Fever accompanied by aches behind the eyes, muscles and joints.
• Rashes
• Recovery within a week
• Severe dengue: Blood in stools and vomit.
• Dengue progresses to severe Dengue.
Treatment
• Seek urgent medical attention.
• Detection of Dengue Virus via Reverse Transcription Quantitative PCR (RT-qPCR).
• Paracetamol only in case you cannot get to a doctor.
• Stay hydrated.
Dengue vaccine
• Sanofi Pasteur Dengvaxia®
• Live attenuated virus
• Approved by FDA in May 2019
• Only for individuals who have been previously infected with Dengue.
• Not approved in India.
GM Mosquitoes
• Aedes aegypti
• Genetically modified to carry a fluorescent marker gene
• Male mosquito eggs carrying a self-limiting gene.
• After fertilization of females, the self- limiting gene terminates females before maturity.
Wolbachia
Image source: Scott O'Neill (Reference)
Chikungunya
Image source: https://commons.wikimedia.org/wiki/User:A2-33
Virus
• Positive single stranded RNA genome (+ssRNA)
• Vectors: Aedes aegypti and Aedes albopictus
• Detection: molecular methods.
• Antibodies.
• Immunity after recovery.
Symptoms
• Fever and joint pain
• Headache, muscle pain, joint swelling
• Rash
• Long-term arthritis
Houseflies
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Pathogens transmitted by houseflies
• Host almost a million bacteria on their bodies.
• Shigellosis
• Typhoid.
• Cholera
• Coliform bacteria
Sandflies
This Photoby Unknown author is licensed under CC BY-SA.
• Leishmaniasis
• Visceral leishmaniasis (VL) (Kala Azar).
• Reported in Africa, India, Iraq.
• Sandfly habitats: moist, dark locations with decaying organic matter.
What can
you for your community?
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Breaking the chain of infection
Understand your vector in terms of habitat, transmission and
susceptibility.
Biorisk Assessment
Assess the risk posed to your community by conducting a
simple risk assessment.
Assess the risk based on apriori and real time data
Mitigate the risk by the application of adequate controls
Assess the performance of the controls after their application
Big data approaches
https://malariaatlas.org/explorer/#/
How do we conduct a risk assessment?
• Setting up a group of volunteers.
• Documenting activities using social media.
• Identify areas which are conducive to breeding of vectors.
• Setting up surveillance systems: insect traps.
• Monitoring the environment for changes in topography due to construction, environmental changes.
• Big data approach.
Data collection:
surveillance
• Collecting data on Mosquitoes by trapping.
• General traps to capture mosquitoes.
• Gravid females can be encouraged to lay eggs in gravid traps.
• Traps for the Dispersal of bioactive compounts
This Photo by Unknown author is licensed under CC BY-NC.
Reference: How to build and install a gravid trap.
(Barrera et al., 2014)
Mosquito Trap
Credits: In2Care Org (https://www.in2care.org/)
In2Care® mosquito trap for disease management
Location &
maintenance.
• Traps should be located within a residential zone at pre-determined locations.
• Monitoring on a daily basis to ensure that the trap is not breached.
• Data analysis in consultation with experts.
• Larvicides can be incorporated into traps.
Biorisk Mitigation
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Controls
• Physical barriers.
• Elimination of breeding sites.
• Chemicals (Plant Derived): Citronella oils.
• Chemical controls: Pyrethins, Pyrethroids.
• Biological controls: Wolbachia, Genetically Modified
mosquitoes, Bacillus thuringinesis.
Managing Vectors is a continuous process.
• Peoples participation.
• Commitment to long-term mitigation.
• Surveillance and intervention.
• Sustainablity of funding.
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