The yellow fever mosquito, Aedes aegypti is a mosquito that can spread the
dengue fever, Chikungunya and yellow fever viruses, and other diseases.
The mosquito is a small, dark mosquito of approximately 4 to 7 millimeters
with typical white markings on the legs and a marking of the form of a lyre on the thorax. Females are larger than males, and can be distinguished by small palps tipped with silver or white scales.
Aedes aegypti is a day biting mosquito. That means that the mosquito is most active during daylight, for approximately two hours after sunrise and several hours before sunset. The mosquito rests indoors, in closets and other dark places. Outside, they rest where it is cool and shaded. The males of all species of mosquitoes do not bite humans or animals of any species, they live on fruit. The female of Aedes aegypti feed not only on fruit, but also on blood. When viewed under a microscope, male mouthparts are modified for nectar feeding, and female mouthparts are modified for blood feeding . The female needs blood to mature her eggs. Feeding on humans generally occurs at one to two hour intervals. The mosquito attacks generally from below or behind, usually from underneath desks or chairs and mainly at the feet and ankles. Aedes aegypti is adapted to breed around human dwellings and prefers to lay its eggs in clean water which contains no other living species. These eggs become adult in about one-and-a-half to two weeks (see also Life cycle of Aedes aegypti).
In dengue virus infected mosquito’s, the virus is present in the salivary glands of the mosquito. When a female Aedes aegypti bites a human for food, she injects saliva into the wound where the anti-coagulants contained in her saliva facilitate feeding. Without knowing, the mosquito also injects the dengue virus into the host. Since the virus can be passed from adult to egg, the dengue virus is guaranteed to survive until the next summer and heavy rains.Dengue is a vector-borne disease transmitted by the bite of an infected mosquito. There are 4 serotypes of the virus that causes dengue. These are known as DEN-1, DEN-2, DEN-3, DEN-4.
Severe dengue is a potentially lethal complication which can develop from dengue infections.
It is estimated that there are over 50-100 million cases of dengue worldwide each year and 3 billion people living in dengue endemic countries.
Dengue is mainly transmitted by a mosquito (Aedes aegypti) and is distributed across all tropical countries .
Dengue outbreaks can occur anytime, as long as the mosquitoes are still active. However, in general, high humidity and temperature are conditions that favour mosquito survival, increasing the likelihood of transmission.
Dengue causes flu-like symptoms and lasts for 2-7 days. Dengue fever usually occurs after an incubation period of 4-10 days after the bite of the infected mosquito.
High Fever (40°C/ 104°F) is usually accompanied by at least two of the following symptoms:
Pain behind eyes
Joint, bone or muscle pains
When developing into severe dengue, the critical phase takes place around 3-7 days after the first sign of illness. Temperature will decrease; this does NOT mean the person is necessarily recovering. On the other hand, special attention needs to be given to these warning signs as it could lead to severe dengue:
Severe abdominal pain
When severe dengue is suspected, the person should be rushed to the emergency room or to the closest health care provider as it causes:
Plasma leaking that may lead to shock and/or fluid accumulation with/without respiratory distress;
Severe organ impairment.
There is no vaccine or specific medication for dengue fever.
Patients should seek medical advice, rest and drink plenty of fluids. Paracetamol can be taken to bring down fever and reduce joint pains. However, aspirin or ibuprofen should not be taken since they can increase the risk of bleeding.
Patients who are already infected with the dengue virus can transmit the infection via Aedes mosquitoes after the first symptoms appear (during 4-5 days; maximum 12). As a precautionary approach, patients can adopt measures to reduce transmission by sleeping under a treated net especially during the period of illness with fever.
Infection with one strain will provide life-time protection only against that particular strain. However, it is still possible to become infected by other strains and develop into severe dengue.
When warning signs of severe dengue are present (listed above), it is imperative to consult a doctor and seek hospitalization to manage the disease.
Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus). These are the same mosquitoes that spread dengue and chikungunya viruses.