Dengue Fever & Zika Virus

Tips Plant Care
January 10, 2019
January 10, 2019

Dengue Fever & Zika Virus


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
Nausea, vomiting
Swollen glands
Joint, bone or muscle pains
Severe dengue
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
Persistent vomiting
Bleeding gums
Vomiting blood
Rapid breathing
Fatigue/ restlessness
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 bleeding;
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.

  • These mosquitoes typically lay eggs in and near standing water in things like buckets, bowls, animal dishes, flower pots and vases.  They prefer to bite people, and live indoors and outdoors near people.
    • Mosquitoes that spread chikungunya, dengue, and Zika are aggressive daytime biters, but they can also bite at night.
  • Mosquitoes become infected when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites.Following its discovery in 1947 until 2007 the Zika virus was regarded as a benign disease, with only 14 documented cases and no hospitalisations or deaths. In 2007 the first serious outbreak occurred, on the Pacific Island of Yap, then in 2015 it erupted in Brazil. By mid-2016 over 60 countries had reported Zika infections and scientists had confirmed a link with serious neurological conditions.WHO has declared it a Public Health Emergency of International Concern and issued a global Strategic Response Plan focussing on the medical complications and integrated mosquito management. WHO regards it as posing a new type of public health threat with long-term consequences for families, communities and countries.The global response will have to revolve around a collaborative effort, relying on governments, NGO’s, researchers and industry to deliver solutions, consisting of education, medical support and innovative mosquito control regimes. Rentokil operations around the globe are contributing towards this goal.
    • Are tests available for the Zika virus?Zika virus infection is confirmed through a blood test performed by a public health laboratory. There are no commercially available tests.
    • Is there a vaccine to prevent Zika virus infection?
      There is no vaccine to prevent Zika. Vaccine development is underway but may not be widely available for 10 years.
    • What treatment is there?
      There is no specific treatment for Zika. Advice given to treat the symptoms is: get some rest; drink fluids to prevent dehydration; consult your doctor about medicines for fever and pain.
    • Who is at risk of a Zika infection?
      Anyone living in or visiting an area where Zika has been confirmed and the sexual partner of a man who has Zika or has visited a Zika area.

Leave a Reply

Your email address will not be published. Required fields are marked *