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| Zika fever | |
 | |
| A mosquito Aedes aegypti, one of the main vectors | |
| Information | |
| Region (s) | Africa, South America (except Chile), Asia and Oceania (except Australia and New Zealand) |
|---|---|
| Cause | Virus (Flavivirus) |
| Vector | Mosquito female Ædes |
| Contagiousness | .svg/15px-Blue_question_mark_(italic).svg.png "Interrogation"){kind=small} unproven (sexual intercourse) |
| CIM-10 | A92.8 |
| CIM-9 | 066.3 |
| Handicap: | Microcephaly in the fetus, Guillain-Barré syndrome |
| Prophylaxis: | |
| * vaccine |  no |
| * medication | no |
| Therapy: | no |
| Location | |
 | |
| Regions infected in January 2016 | |
 Medical warning | |
The Zika fever is a viral disease transmitted by the bite of a female mosquito of the genus Ædes.
 | WARNING : Although the outbreak declared in December 2015 was reported as ended in February 2017 by theWHO, it is necessary to consult the crisis center list of the latter, especially if you are a pregnant woman, before going to a country at risk. (last update: May 29, 2018) |
Understand
The first virus of its kind Zikavirus was identified in 1947 on a Rhesus Macaque (Macaca mulatta) used as a sentinel during a study of the yellow fever in the small forest of Zika near the locality of Kisubi located between Kampala and Entebbe in Uganda. In 1948, the virus was isolated, still in Kisubi, from a female of ’Aedes africanus and transmission by a mosquito like this Ædes was proven in 1956 in a laboratory of Barcelona. Between 1954 and 1981, evidence of human infection was detected in Africa sub-Saharan, on the Indian subcontinent and in South East Asia, however, it was not until 1964 for the first real description of a human case.
The first one epidemic known date of April 2007 and affected the Yap Islands in the West of Federated States of Micronesia. The second raged during the last quarter of 2013 in French Polynesia where it is estimated that a fifth of the population was affected. The current epidemic, although declared in May 2015 at Brazil, would be linked to the organization of the 2014 FIFA World Cup during which the country received tourists from all parts of the world including areas affected by intense strains of the virus. In early January 2016, this epidemic, considered to be emerging, spread to the whole ofSouth America (except at Chile), to Mexico and to Caribbean but also at Green cap, to Tonga and to Maldives. At the beginning of February 2016, 33 countries were affected with the rate of cases declared per number of inhabitants varying from one country to another but affecting more particularly the Colombia.
At the end of 2015, Brazilian doctors demonstrated a correlation between the action of the virus and the increase in cases of microcephaly not congenital with the finding, dated , by the Pan American Health Organization (PAHO) of 3,893 cases suspects and 462 cases confirmed by the presence of the virus in the brain tissue of the fetus or infant. the , the Green cap registers her first case of microcephaly.
The number of cases of patients developing Guillain-Barré syndrome is also on the rise. In early February 2016, Colombia announced that three patients who contracted Zika fever followed by Guillain-Barré syndrome had died. They are thus the first deaths ever observed in direct relation to the presence of the virus. February 11, Venezuela also announces the death of three people who had complications associated with Zikavirus.
Without it being proven that there is any transmission capacity, Brazilian researchers have discovered the Zikavirus, in active form, in the saliva and urine of patients. Stranger, two travelers (an American and a Swiss) who each contracted Zika fever during a stay in a different epidemic zone transmitted the virus to their partner during sexual intercourse. This fact would be a first for a Flavivirus. If cause and effect were to be proven, it would mean that the virus would thus have the possibility of infecting other species ofÆdes to whom he is unknown, like the tiger mosquito (Aedes albopictus), themselves then infecting human beings.
In early March 2016 in Colombia, first case of microcephaly identified and, in Guadeloupe, new discovery with the case of a young patient with transverse myelitis in state phase of his infection due to the presence of the virus in his cerebrospinal fluid.
If theWHO declares the epidemic over , it continued to issue, every month until March 2018, bulletins on the evolution of the disease country by country.
- Crisis center – (in) Country-by-country disease development bulletins issued by theWHO
Location
The era of distribution of the virus is identical to that of its vector, that is to say of most mosquitoes of the genus Ædes, that is, roughly speaking, between the 40e parallel north and the Tropic of Capricorn (except in the Sahara) and, up to an altitude of about 1 000 m.
However, a study conducted at the Institute for Environmental Health ((in)Environmental Health Institute) from Singapore showed that the tiger mosquito (Aedes albopictus), widely distributed throughout the world, including North America and in Europe, is also able to transmit the Zikavirus.
Vector protection
Avoiding Zika fever means first of all avoiding mosquito bites by taking a few precautions. Mosquito females Ædes are activated during the day with peaks of overactivity at dawn and dusk. They are both exophilic, i.e. they live outside homes, and endophiles, i.e. they live inside homes. On the other hand, it is unusual for them to try to take their blood meal on a moving being.
Some protection tips:
- wear loose, long, light-colored clothing;
- as soon as you get up, coat your clothes with Permethrin or the skin of a repellent consisting of a solution containing 30% of DEET for adults or 10% of the same product for children between 2 and 12 years ;
- use an insecticide inside homes;
- use a fan, even if the room has an air conditioning system, since mosquitoes are sensitive to air movement;
- use a mosquito net with a mesh size less than 1,5 mm if you take rest during the day and, if possible, soak it with insecticide which will protect the parts of the body that come into contact with the mosquito net. Before each rest, be sure to check that the mosquito net is in perfect condition.
Be careful that if the females ofÆdes, propagators of Zika fever, yellow fever, from chikungunya and some dengue, are activated between dawn and dusk, females of other mosquito species, which spread other viral diseases, such asJapanese encephalitis and theo’nyong-nyong, or parasitosis such as malaria, are active during the night. The same precautions therefore remain desirable during the night.
Virus protection
At the start of 2016, there was no prophylactic or therapeutic protection against Zikavirus. Research for the creation of a vaccine began in 2015, among others in United States et al'University of Montpellier in France, but researchers estimate that it will take between 10 and 12 years for obtaining a valid vaccine.
The only general prevention methods are either reducing the vector's egg-laying sites by drying up ditches, protecting the water supply with a mosquito net or cover, removing from nature any object that can collect rainwater such as old pans or old tires, or to release into the wild males rendered sterile thanks to an infection caused by a bacterium of the genus Wolbachia where else to release genetically modified male mosquitoes unable to reproduce. It is this latter method, now controversial, that was used in 2015 in Northeast Brazil, that is to say where the epidemic of 2015 started and where the first cases of microcephaly were detected.
Another general prevention method is to set easily workable egg traps. For the latter, it suffices to fill a container with water, to plunge, obliquely, a wooden strip which will allow the female mosquito to rest during the laying and to pour granules or tablets into the water. of larvicide (type "CULINEX Tab plus", etc.) intended to kill the larvae which hatch in the trap.
Diagnostic
It is very difficult to make a valid diagnosis without performing a test RT-PCR as the symptoms are similar to those of other viral diseases such as dengue where the chikungunya, even the rubella, the measles or even the flu if there is no rash.
Symptoms
The main symptoms appear after incubation phase which lasts from 3 to 12 days. This is a subfebrile state chronic, headache, muscle and joint pain (mainly in the ankles and hands), a feeling of general tiredness, conjunctivitis, of a exanthema starting on the face before spreading to the rest of the body. These symptoms may be accompanied by gastric disorders and neurological disorders such as dizziness or lightheadedness.
Clinical signs
THE'history will be followed by a test ELISA to detect the presence ofantibody anti-Zika immunoglobulin M (IgM) type or the presence ofantigens viral. IgMs are detectable 3 days after the start of the invasion phase. However, this test may exhibit cross-reactions with the presence of other Flavivirus, especially with the person responsible for dengue, especially if the patient has had a previous infection with Flavivirus.
The only definitive diagnosis will be based on a test RT-PCR, made possible since 2006 and the sequencing of the genome of Zikavirus, which makes it possible to detect the presence of the viral enzyme specific to Zikavirus in serum and urine. This test can be done within a period of up to 15 days, for urine, after the onset of the invasion phase.
- RT-PCR of Zikavirus – Conduct of an RT-PCR test performed by the Central Laboratory of Clinical Biology of the Prince-Leopold Institute of Tropical Medicine.
Therapy
There is no therapy to combat the Zikavirus. The only thing to do is to isolate the patient, under a mosquito net in the areas at risk, for a week; this so that it is not transplanted by a healthy mosquito which would infect someone else or by an already infected mosquito which would inoculate it again with the virus or any other infection. The patient will be hydrated regularly and, eventually, will receive analgesics and antipyretics based on paracetamol to combat hyperthermia and calm pain while avoiding the use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or aspirin, which may induce an externalized hemorrhage common in flavivirosis. If theexanthema is disturbing for the patient, diphenhydramine (such as “Diphamine”, “R Calm®”, etc.) may be applied locally to the injured areas.
After one viremia ranging from 2 to 5 days, asymptomatic in approximately 80% of cases, the patient will not have any sequelae, except in rare cases.
Possible consequences
- Microcephaly for the fetus appearing in the infant stage.
- Guillain-Barré syndrome with cases twice as high in women than in men.
Remarks
- Returning from an area at risk of Zika fever, less than 28 days, temporarily excludes you from donating blood to the Canada, in France and in Britain.
Further information
- Media center – The Zika fever page on theWHO.
- Zika virus warning – The Zika virus page on the Prince-Leopold Institute of Tropical Medicine website.
