When a mosquito feeds on blood, it also swallows any viruses or parasites dwelling in the blood. These viruses and parasites can be transferred to the next person the mosquito bites through its saliva. Any disease that is spread in this way, from mosquito to human (or animal), is known as a 'mosquito-borne disease'.
While the mosquito may not be affected, these mosquito-borne diseases can cause immense suffering for humans. More than 700 million people are killed by these mosquito-borne illnesses every year.
Let’s take a detailed look at some of these diseases:
Dengue
According to the World Health Organization (WHO), Dengue is the most critical mosquito-borne disease in the world. It's also the most rapidly spreading in recent decades with 100 to 400 million infections each year.
Dengue fever is caused by a virus transmitted primarily by Aedes aegypti mosquitoes. These mosquitoes bite during the day, usually just after sunrise and around sunset.
Symptoms include high fever, headaches, vomiting, joint pain & rashes which typically last for 2 - 7 days.
According to the World Health Organization (WHO), nearly half of the world's population was at risk of malaria in 2019. There were an estimated 229 million cases of infections reported that year 409, 000 people losing their lives to the disease.
Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes.
Symptoms include fever, headache and chills, which at first, might be difficult to identify, as malaria. These symptoms usually begin to appear 10 to 15 days after the infective bite.
Chikungunya virus is spread to people by the bite of an infected mosquito. While rarely fatal, it can cause debilitating joint pain that can last for weeks. The word ‘chikungunya’ comes from the Kimakonde language. It means ‘to become contorted’, as the disease causes debilitating joint pain that induces a stooped appearance.
It is caused by a virus transmitted primarily by Aedes aegypti mosquitoes. These mosquitoes bite during the day, usually just after sunrise and around sunset.
Symptoms may include sudden-onset fever, joint and muscle pain, rash, headache or fatigue.
Chikungunya causes high fever and debilitating joint pain, and shares some clinical signs dengue, which sometimes leads to misdiagnosis in areas where these diseases are prevalent. Symptoms usually improve within a week, however, sometimes the joint pain may last for months.
Congo Virus or Crimean-Congo Haemorrhagic fever (CCHF) is a tick-borne viral disease that infects wild and domestic animals, including livestock. Humans can contract this disease by getting bitten by an infected tick living on the host animal or coming into contact with the blood, tissues or fresh meat of the infected animal. Human-to-human transmission is also possible in case of close contact with the organs, blood or other secretions and bodily fluids of the infected person.
This virus is a threat to public health services as the virus can lead to epidemics as it has a high case fatality ratio (10% - 40%).
The initial symptoms include headache, high fever, back pain, joint pain, stomach pain, and vomiting. Red eyes, a flushed face, a red throat, as well as petechiae (red spots) on the palate are common. Symptoms may also include jaundice, and in severe cases, changes in mood and sensory perception.
Sources:
https://www.who.int/news-room/fact-sheets/detail/vector-borne-diseases
https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue
https://www.pharexmedics.com/studies/differences-between-malaria-and-dengue
https://www.who.int/news-room/fact-sheets/detail/malaria
https://www.who.int/news-room/fact-sheets/detail/chikungunya
https://www.who.int/health-topics/crimean-congo-haemorrhagic-fever/#tab=tab_1
https://www.cdc.gov/vhf/crimean-congo/symptoms/index.html
