Question

What role do disease vectors play in the spread of vector-borne diseases? Explain with some vector examples and their hosts; using mosquitos as an example, describe major mosquitos-borne diseases and their control and prevention.

Answer 1

Vector-borne diseases are the diseases that are transferred from an infected individual or source of infection to a healthy individual with the help of Vectors which include mosquitoes, flies, ticks, rats etc. These vectors carry with them bacteria, viruses and protozoa that cause a particular disease.

Example:

Dieases vector host

Lyme disease Ticks white-footed mouse and birds

Dengue mosquito human

Malaria mosquito human

Plague flea rats

Encephallitis mosquito human, cattle, and horses

Major Mosquito borne disease -

i. Malaria

Malaria is transmitted by female anopheles mosquito bite. the mosquito carries the parasite Plasmodium from an infected individual to a healthy individual. Malaria can also be transmitted by blood transfusion, organ transplant and sharing needles or syringes. there are four types of malarial parasites that infect humans: Plasmodium vivax, P. ovale, P. malariae, and P. falciparum.

After the mosquito bites, the parasite travels to the liver where they mature and are then released into blood stream In blood they attack RBCs , where they multiply and increase in number. Gametogenesis takes places in blood from where gametes are picked up by mosquitoes, The formation of zygote and maturation takes place inside mosquitoes.

Symptoms of malaria include high fever, sweating, headache, nausea, abdominal pain followed by diarrhoea, muscle ache, amenia and in some extreme cases blood in stool.

Control and prevention-

1. use of mosquito repellents

2. wearing full sleeves clothes

3. preventing the accumulation of water in open that can serve as breeding grounds for mosquitoes.

4. Insecticide spray and fumigation that serve as larvicides.

ii. Dengue

Dengue virus or DENV  is carried by Ades aegypti mosquito and the hosts are human. Symptoms are high fever, muscle ache, joint ache , nausea, vomiting ,pain behind eyes and in extreme cases hemorrhage and clotting of blood.

Preventive measures are same as that of Malaria because both are mosquito borne diases.