Vector-Borne Diseases- Types, Causes & Prevention

Overview  

Vector-borne diseases are illnesses caused by the bite of disease-causing pathogens like mosquitoes, houseflies, ticks etc. There are various vector-borne diseases, including Malaria, Dengue, Yellow Fever, Plague, Zika Virus, etc.  

This blog discusses the types, causes, symptoms and treatment of different vector-borne diseases.

Vector-borne diseases are illnesses caused by parasites, viruses and bacteria transmitted by vectors. Vectors are living organisms that transmit infectious pathogens between humans or from animals to humans.   

These vectors are bloodsucking insects that ingest disease-producing parasites from an infected host during a blood meal and then transmit them to a new host.

After becoming infectious, vectors can transmit infections for the rest of their life during each bite.

According to WHO, about 700,000 deaths occur due to vector-borne diseases like Malaria, yellow fever, dengue, chikungunya, onchocerciasis, leishmaniasis etc.

Arthropod species like mosquitoes, ticks, bugs, sandflies and blackflies usually transmit vector-borne diseases.

The spread of disease usually depends on the environment, population density, urbanisation etc. People living near water bodies, dense grass growth regions, etc., may experience vector-borne disease outbreaks.

However, many of these vector-borne diseases are preventable through proper protective measures.

Types of vectors that spread vector-borne disease

Vector- Borne Disease	Type of pathogen	Vectors
Chikungunya, Dengue, Yellow Fever, Zika	Virus	Aedes Mosquito
Malaria	Parasite	Female Anopheles mosquito
Japanese encephalitis and West Nile fever	Virus	Culex mosquito
American trypanosomiasis	Parasite	Triatomine bugs
African trypanosomiasis (Sleeping sickness)	Parasite	Tsetse flies
Leishmaniasis	Parasite	Sandflies
Typhus	Bacteria	Lice
Plague	Bacteria	Fleas (transmitted from rats to humans)
Crimean-Congo hemorrhagic fever	Virus	Ticks
Lyme disease	Bacteria	Ticks

How severe is vector-borne disease?  

Vector-borne diseases are among the most severe and unpredictable conditions. The prevention and control of these diseases are extremely challenging since the organisms are inherent to the environment where they are spreading.

Vector-borne diseases pose a greater threat than diseases transmitted through human contact due to their ability to spread faster and on a larger scale. They transmit diseases from different animals, including mice, rats, monkeys, birds, dogs, etc., to humans and open the door to spreading microorganisms that cause severe illnesses. Treating such diseases is difficult, and the vector must be eliminated to prevent the spread of diseases.

Causes of Vector-borne disease   

Vector-borne diseases are caused by the bite of infected vectors like mosquitoes, ticks, black flies, snails or sandflies, which are the primary carriers of the disease. These vectors suck human blood; it ingests the disease-causing pathogen from an infected animal or human and then transmit it to other humans.

Possible places of presence of disease-causing vectors

• Swimming pools and ponds with stagnant water
• Places where rainwater stagnates, like parks
• Equipment and places that have been abandoned
• Toilets or kitchens with open water tanks
• Water stagnant in flower pots
• Burrows of rodents and dark places
• Buildings with stagnant water on their roofs
• A swimming pool, pond or swamp, especially in an agricultural area
• Animal husbandry and agricultural sheds   
• Beds and unhygienic sleeping areas   

Types of disease caused by mosquitoes, flies and snails include

Causative Organisms	Vector-Borne Disease
Mosquito-borne diseases	Malaria, Dengue fever, Yellow fever, Chikungunya, Elephantiasis
Flies	Dysentery, Diarrhoea, Typhoid, Cholera, Shigellosis, Certain helminth infections, Eye infections – trachoma and epidemic conjunctivitis
Ticks	Lyme disease, Tick-borne meningo encephalitis, Crimean–Congo hemorrhagic fever, Tick-borne relapsing fever, Qfever, Tick-borne spotted fevers, Babesiosis, Ehrlichiosis Tularemia
Snails	Angiostrongyliasis, Clonorchiasis, Fascioliasis, Paragonimiasis, Schistosomiasis

Symptoms of Vector-borne disease  

The symptoms of vector-borne diseases vary depending on the conditions and the disease-causing pathogens. Some common symptoms include

Disease	Symptoms
Chikungunya	Fever, Joint pain, Muscle ache, Headaches, Nausea, Fatigue, Skin rashes, Joint Pain may last for weeks
Dengue	Sudden high fever, Severe headache, Muscle pain, Joint pain, Nausea, Vomiting, Swollen lymph, Skin rashes
Yellow Fever	Fever, Muscle pain, Chills, Headaches, Loss of appetite, Nausea, Abdominal pain, In severe cases symptoms include gastric bleeding, dark coloured urine, vomiting
Zika Virus	Moderate fever, Conjunctivitis, Headache, Joint stiffness, muscle pain, Eye Pain
Malaria	Fever, Chills, Sweating, Headache, Nausea, Body aches, Diarrhea, Vomiting, Breathing issues, Chest pain, In severe cases malaria leads to Jaundice.
Japanese encephalitis	Fever, headache, Vomiting, Neurological symptoms, About 20 to 30 per cent of people die who reports brain infection
West Nile Fever	Fever, Headache, Fatigue, Body aches, Nausea, Skin rashes
Plague	Pneumonia, Shortness of breath, Chest pain, Cough, Bubonic Plague fills sores with pus
Typhus	High fever, Headache, Chills, Coughing, Severe muscle pain Fatigue

Treatment of Vector-Borne disease

Viral vector-borne diseases can’t be treated. Parasitic infections like Malaria and Dengue can be treated using drugs like quinone, which prevents pathogen growth. Doxycycline and chloramphenicol are used to treat bacterial infections.  

Here are some preventive measures to protect you from vector-borne disease

• One can take vaccines to prevent vector-borne diseases like yellow fever, encephalitis and more.
• Take necessary precautions before you travel to vector-borne disease outbreak locations.
• Always maintain hygiene, and make sure there’s no stagnant water near your place.
• Cover your body from head to toe before going outside.
• Apply insect/mosquito repellents on unprotected skin.
• Avoid contact with infected people or animal
• Check the vessels before cooking and food storage. Maintain healthy hygiene.
• Get vaccinated against all the diseases.

Summary  

A major aspect of vector-borne diseases is behavioural change. Educating the people and improving awareness becomes necessary for people to protect themselves and their communities from mosquitoes, ticks, bugs, flies and other such vectors and diseases.  

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