Question

Read the following passage and answer the questions that follow:

“Mosquitoes are drastically affecting the human health in almost all the developing tropical countries. Different species of mosquitoes cause very fatal diseases so much so that many humans loose their life and if they survive, are unable to put in productive hours to sustain their life. With the result the health index of the country goes down.”

(a) Name the form in which Plasmodium gains entry into

1. human body
2. the female Anopheles body.     [1]

(b) Why do the symptoms of malaria not appear in a person immediately after being bitten by an infected female Anopheles? Give one reason. Explain when and how do the symptoms of the disease would appear.    [2]

                                              OR

(b) Explain the events which occur within a female Anopheles mosquito after it has sucked blood from a malaria patient.    [2]

(c) Name a species of mosquito other than female Anopheles and the disease, for which it carries the pathogen.    [1]

Answer 1

(a)

1. Entry into the human body: Plasmodium enters the body as sporozoites.
2. Entry into the female Anopheles body: Plasmodium enters the female Anopheles mosquito as gametocytes.

(b) Malaria symptoms often occur 7–30 days after being bitten by an infected female Anopheles mosquito.
Plasmodium parasites enter the bloodstream as sporozoites after being bitten by an infected mosquito, which may explain the delayed start of symptoms. Sporozoites go to the liver to replicate and mature within hepatocytes. During the pre-erythrocytic phase, parasites multiply without generating any symptoms. The infection phase varies by Plasmodium species and can range from a few days to weeks.
After the pre-erythrocytic phase, mature parasites are liberated from the liver and enter the bloodstream. They then replicate in red blood cells (erythrocytes). Malaria symptoms often occur during the erythrocytic phase of the infection. Parasites destroy red blood cells, releasing toxins and prompting an immune system response. Symptoms include fever, chills, headache, lethargy, and muscle aches.

                                              OR

(b) 

1. Female Anopheles, a mosquito, feeds on infected human blood, ingesting gametocytes, the sexual stage of the malaria parasite.
2. After ingestion, mosquitoes grow gametocytes in their stomach wall, where male and female gametes unite to form a zygote. After initial development, the zygote differentiates into sporozoites.
3. The sporozoites migrate from the stomach wall to several organs in the mosquito's body cavity. Many entities penetrate the salivary glands of the mosquito, where they accumulate and remain poised for transfer to a new host.
4. An infected female Anopheles mosquito bites a healthy person and injects saliva containing sporozoites into their bloodstream. Malaria infection begins with the passage of sporozoites through saliva.

(c) Aedes aegypti: It carries the pathogens responsible for dengue fever.