By Kimani Wiseman
“Small axe cuts down big trees.” We can apply this expression to mosquitoes. The length of an adult mosquito is between 3mm and 6mm, sometimes it is hard to envision that an insect so small has sent so many people to their graves around the world. A World Health Organization article states that the mosquito’s ability to carry and spread diseases to humans causes millions of deaths every year.
Some of the diseases that mosquitoes spread are: zika, dengue, West Nile virus, malaria, yellow fever, eastern equine encephalitis, chikungunya. Zika virus is caused by a virus transmitted primarily by aedes mosquitoes, which bite during the day. Symptoms typically last for two to seven days. Zika virus during pregnancy can cause infants to be born with “microcephaly”, a condition where a baby is born with a small head or the head stops growing after birth. Brazil had a number of cases of microcephaly between 2015 and 2016.
Chikungunya is a viral disease transmitted to humans. The virus is transmitted from human to humans by the bites of infected female mosquitoes. Most commonly, the mosquitoes involved are aedes aegypti and aedes albopictus, two species which can also transmit other mosquito-borne viruses. Chikungunya causes fever and severe joint pain. Other symptoms include muscle pain, headache, nausea, fatigue and rash. Joint pain is often debilitating and can vary in duration. Those with symptoms usually get ill three to 12 days after being bitten by an infected mosquito. In 2014, in St.vincent and the Grenadines, many persons would recall that they had to take sick leave because of the amount of pain they were experiencing because of chikungunya.
Eastern equine encephalitis (EEE) is an extremely rare but serious and often fatal infection that causes encephalitis or inflammation of the brain. It is spread by the bite of a mosquito infected with EEE virus. Symptoms of EEEV infection typically appear four to10 days after being bitten by an infected mosquito. Severe cases of EEE infection begin with the sudden onset of headache, high fever, chills and vomiting that may progress into disorientation, seizures, encephalitis [inflammation of the brain]. According to a CNN news article published on Oct. 3, 2019, 11 persons have died thus far from EEE in the United States.
Dengue viruses are spread to people through the bite of an infected Aedes aegypti mosquito. Dengue is common in more than 100 countries across the world. Forty percent of the world’s population, about three billion people, live in areas with a risk of dengue. The most common symptom of dengue is fever with any of the following: nausea, rash, aches and pains (eye pain, typically behind the eyes, muscles, joint or bone pain). Symptoms of dengue typically last two to seven days. Most people will recover after about a week. Each year, an estimated 390 million dengue infections occur around the world. Of these, 500,000 cases develop into dengue haemorrhagic fever, a more severe form of the disease. A Jamaica Observer article published on Oct. 14, 2019 states that for the period Jan.1, 2018 to Sept. 30, 2019, there were 135 suspected and confirmed dengue-related deaths in Jamaica. These included 47 cases in 2018 and 88 in 2019. The article further went on to state that there were 10 suspected deaths in September 2019.
Mosquitoes target people who emit more carbon dioxide when they breathe, such as people with larger body size or pregnant women. Mosquitoes can detect carbon dioxide from as far as 50 meters (164 feet) away. They also prefer people with type O blood. Researchers found that people with type O blood are twice as attractive to mosquitoes than those with type A or B blood. Besides the blood group, 85% of people produce a chemical signal that indicates what blood type they are. Mosquitoes can smell lactic acid, uric acid, and other compounds emitted in your sweat.
Strenuous exercise increases the build-up of lactic acid and heat in your body, which makes you more attractive to mosquitoes than others. High body temperature can make you more easily found by mosquitoes. Studies show that pregnant women attract twice as many mosquito bites as others. This is due to the fact they exhale about 21% more carbon dioxide than others. The types and amount of bacteria that naturally live on human skin affect our attractiveness to mosquitoes. A mix of microbes and chemicals that we produce make up our unique body odour. Mosquitoes can detect these attractive aromas.
The long “nose” that female mosquitoes pierce into your skin is actually a cluster of six different needles like spires which have different purposes. Two of these spires have tiny teeth which she uses to saw into your skin. Two other of these spires hold open the skin, like forceps. One of these needles looks around for blood and acts as a “straw” for her to ingest it. The last of them excretes a chemical into your skin that makes your blood flow to her easily so she can use her straw and this chemical is what irritates the skin. The itchy bump you get is an allergic reaction to that chemical. Sometimes in that secretion, the female mosquito leaves behind a dangerous pathogen, which is how dangerous diseases are transmitted. This process happens very fast in the blink of an eye. Climate change is already causing warmer temperatures and heavy rainfall which would make conditions more suitable for the Aedes aegypti mosquito to survive, hence the reason measures need to be put in place to combat against mosquitoes.
Here are some tips for alleviating the mosquito population:
- There are some persons who keep a lot of vehicle tyres around their house. During the rainy season, this can be a habitat for mosquitoes. Instead of having tyres around your house breeding mosquitoes, these tyres can be filled with soil and you can plant vegetables in them or you can paint the tyres and plant flowers in them and beautify your garden. Those who are good at up-cycling, in Nigeria a female entrepreneur is using old tyres and making furniture.
- Do not litter in gutters and in streams, this would block the free flow of water which would cause the mosquito population to increase. Female mosquitoes lay their eggs in stagnant water.
- Persons who usually keep water around their house in barrels and buckets must ensure that this water is covered all the time. Farmers usually store a lot of water on their farm and most of the time when persons from the vector control unit visit their homes they are not at home and would miss out on educational information about mosquitoes hence the reason I would strongly recommend if the Ministry of Health in collaboration with the Ministry of Agriculture can have a workshop to sensitize farmers about storing water safely on the farm.
- There are insect repellents that persons can use on their skin, you can also use an insecticide spray in your house, or you can sleep under a mosquito net to avoid being bitten.
- Fish eats the larvae of mosquitoes, in the event there is an empty pond anywhere, having some fish in these ponds would be a good idea.
- Persons who usually keep a vase in their house with water should change the water regularly. Sleeping with a fan can also deter mosquitoes from biting you.
Mosquitoes are extremely dangerous insects which require all “hands on deck” to reduce the mosquito population, to prevent an outbreak of diseases, which can sick and kill a lot of people.