Arthropod borne & Zoonotic viral infections-ARBOVIRUSES & Alpha viruses Flashcards
Viruses transmitted from blood sucking athropods (mosquitoes, ticks, and sandflies) to vertebrates (humans)
Arboviruses
What are the two widely known alpha viruses?
- Chikungunya virus
- Sindibis virus (Birds are resevoirs: mosquitos get infected by feeding infected blood of birds, and then will infect human by biting them afterwards)
Prevalence of arboviruses is expanding,
with these viruses causing >17% infectious diseases globally. What factors aid in wide sread of such infections?
*~135 arboviruses are known to date
- travel,
- trade and
- tourism
Genome of arboviruses?
They are RNA
Clinical presentation of arboviruses
- febrile illness (ones tht cause an increase in body temp)
- haemorrhagic fever or
- neurological disease
The 3 stages of spread of the Arboviruses
- Pre-emergence
- Localised emergence
- Pandemic emergence
Pre emergence stage of the Arbovirus infections is aided by what factors?
- Deforestation
- Land use intensification
- Disturbance of habitats
localised emergence stage of the Arbovirus infections is aided by what factors?
- Extension of the interphase
- localised outbreaks
Pandemic emergence stage of the Arbovirus infections is aided by what factors?
- Urbanisation,
- Global travel and trade
- Sustained person-to-person outbreaks
Vector of the Crimean- Congo Haemorragic Fever
Tick
*genus hyelomma
The modes of transmission of Crimean-Congo Haemorragic Fever
- Animal to animal transmission (animals of concern: rabbits, birds, rodents, cattle, sheep, goats and ostriches):
-through bite from infected tick
-through direct contact of bodily fluids of infected animal - Animal to human transmission:
-Through bite from infected tick
-Direct contact with the blood or organs of infected animals - interhuman transmission (human to human):
-through direct contact with the blood and other bodily fluids,
secretions and organs of an infected person
A viral infection presenting symptoms to humans, but remains asymptomatic in animals
Crimean-Congo Haemorragic Fever
Vector of Rift Valley Virus
mosquitos
- particulary: (Aedes, Culex and Anopheles)
This virus has a reservoir, and a reservoir is a wild herbivore
Rift valley fever
Different modes of transmissions of rift valley fever
- Animal to animal transmission
through:
-Mosquito bites
-Contact with infected bodily secretions esp blood - Human transmissions
through:
-mosquito bites
-Direct contact with the blood or organs of infected animals
-Consumption of raw/ undercooked meat or unpasteurised dairy products
*Here we do not have ‘human to human’ transmission
Environmental conditions favouring prevelance or occurance of rift valley fever
- Heavy rainfall
- Unseasonably warm temperatures
*They favour mosquito breed and their activity
What are principal symptoms of rift valley fever in humans?
- Flu like symptoms
- More severe:
-Bloody vomiting,
-loss of vision and
-neurological complications
Warning signs seen in animals that rift valley fever might be taking place
- High mortality in animals
- Large scale Arbortion
- High fever – other signs such as anorexia (leads to low body weight), jaundice, diarrhoea and nasal discharge
People at risk for rift valley fever infection
- people who raise animals,
- vets,
- agricultural and slaughterhouse workers
A viral infection transmitted to humans through bite of mosquitos. But we have different species of mosquitos transmitting disease in urban areas, as well as in forests
Yellow fever
*Mosquitos transmitting disease in forests- Haemagogus and Sabethes species_(sylvatic cycle)
* In urban areas: Aedes aegypti_(urban cycle)
What is a mosquito-borne fever from a female Aedes mosquito.
Dengue fever
Symptoms of Dengue fever
- Severe headache,
- high fever,
- pain behind the eyes,
- nausea and vomiting,
- swollen glands/rash,
- muscle and joint pains
- and chills
What are the sever dengue signs?
- severe bleeding and
- respiratory distress
What’s the vector of Zika virus?
mosquito
what are the transmission routes of Zika virus?
- Mother to Child transmission
- Sexual transmission
- Blood transfusion
What are the possible symptoms seen with Zika virus?
Rash, headache, fever, itchy eyes
How are alpha viruses transmitted to humans?
Via mosquito bites
What are possible symptoms of Chikungunya virus?
- Joint and Back pain,
- rash,
- headache,
- chills,
- vomiting,
- fever,
- nausea
An alpha virus causing non- specific febrile illness: defined by rash and arthralgia (joint pain)
Sindibis virus
Treatment for Sindbis viral infection
- Antihistamines for itchy rash
