Medical experts say mosquito bites can lead to the transmission of serious diseases and viruses which can lead to disabling and potentially deadly effects.
Such mosquito-borne diseases include elephantiasis of the scrotum and other parts of the body such as as legs, hands and breasts.
Other mosquito-borne diseases are yellow fever, dengue fever and malaria.
However, physicians say, with protective measures, community mobilisation and behavioural change, mosquito bites can be controlled and eliminated.
According to the Nigeria Centre for Disease Control, the female anopheles mosquitoes are generally known to transmit malaria from man to man.
The agency notes that malaria is a life-threatening disease caused by Plasmodium parasites.
“The intensity of malaria transmission depends on factors related to the parasite, the vector, the human host, and the environment. The female mosquitoes seek a blood meal to nurture their eggs.
“In 2015 alone, there were an estimated 214 million new cases of malaria and 438,000 deaths.
“Sub-Saharan Africa carries a disproportionately high share of the global malaria burden. In 2015, the region was home to 88 percent of malaria cases and 90 percent of malaria deaths, globally.
“Nigeria accounted for up to 25 percent of the global cases and deaths,” the agency said.
It added that malaria is preventable and curable, and that increased efforts are dramatically reducing the malaria burden in many places.
Also, the Aedes mosquitoes are known to be the most notorious in spreading diseases. They are usually found in floodwater pools, wetlands, and inside natural or artificial containers.
Professor Jeffrey R Powell of Yale University called Aedes mosquito ‘the most dangerous animal in the world’ in his paper titled ‘New contender for most lethal animal,’ published in online peer-reviewed journal Nature in 2016.
Also, a study by researchers at Texas-based Baylor College of Medicine states that Aedes mosquitoes can be identified by the distinctive black and white markings on their bodies and legs.
“Unlike most other mosquitoes, Aedes mosquitoes are active and bite only during the daytime, with peak activity during the early morning and in the evening before dusk,” the study says.
The NCDC adds that both Aedes and Haemagogus species of mosquitoes are known to transmit yellow fever, an acute viral hemorrhagic illness caused by the yellow fever virus, an RNA virus that belongs to the family Flaviviridae.
The agency said the yellow fever virus has three transmission cycles, namely jungle (sylvatic), intermediate (savannah), and urban.
Aedes is also known to be responsible for dengue fever transmission.
It said the Yellow fever virus is found in tropical and subtropical areas of Africa and Central/South America with the illness being endemic in 34 African countries (including Nigeria) and 13 Central and South American countries.
“Transmission of the virus in Africa is maintained by a high density of Aedes mosquito populations that are in close proximity to largely unvaccinated human populations.
“Occasionally, infected travellers from areas where yellow fever occurs have exported cases to countries that are free of yellow fever.
“There is currently no specific treatment for yellow fever. Good and early supportive treatment in hospitals, including treating dehydration and undernutrition, management of metabolic acidosis, liver and kidney failure, correcting clotting abnormalities, and antibiotic treatment for secondary bacterial infections improve survival rates.
“Vaccination with the yellow fever vaccine provides lifelong protection and is the most important means of preventing yellow fever.
“Vaccination strategies useful in the prevention of yellow fever disease and its transmission include: the risk of transmission in urban areas can be reduced by eliminating potential mosquito breeding sites e.g. places and containers where standing water collects.
“Vector surveillance and control are components of transmission control in epidemic situations. Targeting Aedes aegypti and other Aedes species in terms of vector surveillance will help inform where there is a risk of an urban outbreak,” NCDC said.
Dengue and Yellow fever viruses are also transmissible via blood transfusions but not via secretions or direct blood contact.
The World Health Organisation says dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas.
Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to 14 days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic skin rash.
The world health body noted that severe dengue is a leading cause of serious illness and death in some Asian and Latin American countries. It requires management by medical professionals, while it is also vaccine preventable.
“While many dengue fever infections produce only mild illness, it can cause an acute flu-like illness. Occasionally this develops into a potentially lethal complication, called severe dengue,” it noted.
Culex is a genus of mosquitoes, several species of which serve as vectors of one or more important diseases of birds, humans, and other animals.
WHO noted that culex species of mosquitoes breed in a large variety of still waters, ranging from artificial containers and catchment basins of drainage systems to large bodies of permanent water.
“The most common species, Culex quinquefasciatus, a major nuisance and vector of bancroftian filariasis, breeds especially in water polluted with organic materials such as refuse and excreta or rotting plants,” WHO says.
Examples of such breeding sites are soakaway pits, septic tanks, pit latrines, blocked drains, canals, and abandoned wells.
Experts at the United States National Institutes of Health say the bancroftian filariasis disease is the second most common cause of disability worldwide after leprosy.
Bancroftian filariasis is a mosquito-borne disease caused by the nematode Wuchereria bancrofti.
Wuchereria bancrofti is a filarial nematode that is the major cause of lymphatic filariasis. It is one of the three parasitic worms, together with Brugia malayi and B. timori, that infect the lymphatic system to cause lymphatic filariasis, an example of which is elephantiasis, which is the enlargement of affected body parts such as legs, scrotum, etc.
“In many developing countries, Culex quinquefasciatus is common in rapidly expanding urban areas where drainage and sanitation are inadequate.
“Culex tritaeniorhynchus, the vector of Japanese encephalitis in Asia, prefers cleaner water. It is most commonly found in irrigated rice fields and in ditches,” WHO said.
According to a Professor of Public Health and former National Chairman of the Association of Public Health Physicians of Nigeria, Prof. Tanimola Akande, the common mosquitoes in Nigeria include various species of Anopheles, Aedes, and Culex.
He said, apart from the mild pain and irritation at the site of the bite, mosquito bites can lead to the transmission of diseases.
“Diseases that are spread to people by mosquitoes include malaria, yellow fever, dengue fever, elephantiasis, and a number of other diseases.”
He said vector control measures must be put in place to control or prevent mosquito bites.
“Vector control measures, which include good environmental hygiene, prevent breeding places for mosquitoes like poor drainage, poor waste disposal, ponds and pools of water collection often result from poor waste disposal.
“Protective materials should be readily available like insecticide-treated nets, particularly for at-risk groups like pregnant women and children under five years of age.
“Insecticide sprays and other devices that kill mosquitoes should be used regularly to prevent mosquito bites,” Akande said.
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