Zika Virus

KEY FACTS :

  • Zika virus disease is caused by a virus transmitted by Aedes mosquitoes.
  • People with Zika virus disease usually have a mild fever, skin rash (exanthema) and conjunctivitis. These symptoms normally last for 2-7 days.
  • There is no specific treatment or vaccine currently available.
  • The best form of prevention is protection against mosquito bites.
  • The virus is known to circulate in Africa, the Americas, Asia and the Pacific.

 

INTRODUCTION : 

Zika virus is an emerging mosquito-borne virus that was first identified in Uganda in 1947 in rhesus monkeys through a monitoring network of sylvatic yellow fever. It was subsequently identified in humans in 1952 in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.

Genre: Flavivirus

Vector: Aedes mosquitoes (which usually bite during the morning and late afternoon/evening hours)

Reservoir: Unknown

 

SIGNS AND SYMPTOMS :

The incubation period (the time from exposure to symptoms) of Zika virus disease is not clear, but is likely to be a few days. The symptoms are similar to other arbovirus infections such as dengue, and include fever, skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache. These symptoms are usually mild and last for 2-7 days.

During large outbreaks in French Polynesia and Brazil in 2013 and 2015 respectively, national health authorities reported potential neurological and auto-immune complications of Zika virus disease. Recently in Brazil, local health authorities have observed an increase in Zika virus infections in the general public as well as an increase in babies born with microcephaly in northeast Brazil. Agencies investigating the Zika outbreaks are finding an increasing body of evidence about the link between Zika virus and microcephaly. However, more investigation is needed before we understand the relationship between microcephaly in babies and the Zika virus. Other potential causes are also being investigated.

 

TRANSMISSION : 

Zika virus is transmitted to people through the bite of an infected mosquito from the Aedes genus, mainly Aedes aegypti in tropical regions. This is the same mosquito that transmits dengue, chikungunya and yellow fever.

Zika virus disease outbreaks were reported for the first time from the Pacific in 2007 and 2013 (Yap and French Polynesia, respectively), and in 2015 from the Americas (Brazil and Colombia) and Africa (Cape Verde). In addition, more than 13 countries in the Americas have reported sporadic Zika virus infections indicating rapid geographic expansion of Zika virus.

 

DIAGNOSIS :

Zika virus is diagnosed through PCR (polymerase chain reaction) and virus isolation from blood samples. Diagnosis by serology can be difficult as the virus can cross-react with other flaviviruses such as dengue, West Nile and yellow fever.

PREVENTION : 

Mosquitoes and their breeding sites pose a significant risk factor for Zika virus infection. Prevention and control relies on reducing mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people.

This can be done by using insect repellent; wearing clothes (preferably light-coloured) that cover as much of the body as possible; using physical barriers such as screens, closed doors and windows; and sleeping under mosquito nets. It is also important to empty, clean or cover containers that can hold water such as buckets, flower pots or tyres, so that places where mosquitoes can breed are removed.

Special attention and help should be given to those who may not be able to protect themselves adequately, such as young children, the sick or elderly.

During outbreaks, health authorities may advise that spraying of insecticides be carried out. Insecticides recommended by the WHO Pesticide Evaluation Scheme may also be used as larvicides to treat relatively large water containers.

Travellers should take the basic precautions described above to protect themselves from mosquito bites.

TREATMENT :

Zika virus disease is usually relatively mild and requires no specific treatment. People sick with Zika virus should get plenty of rest, drink enough fluids, and treat pain and fever with common medicines. If symptoms worsen, they should seek medical care and advice. There is currently no vaccine available.

 

WHO RESPONSE

WHO is supporting countries to control Zika virus disease through:
  •  Strengthening surveillance;
  •  Building the capacity of laboratories to detect the virus;
  •  Working with countries to eliminate mosquito populations;
  •  Preparing recommendations for the clinical care and monitoring of persons with Zika virus infection; and
  •  Defining and supporting priority areas of research into Zika virus disease and possible complications.

Swine Flu – H1N1 Flu

DEFINITION : 

Technically, the term “swine flu” refers to influenza in pigs. Occasionally, pigs transmit influenza viruses to people, mainly to hog farmers and veterinarians. Less often, someone infected with swine flu passes the infection to others.

The human respiratory infection caused by a particular influenza virus H1N1 strain — popularly known as swine flu — was first recognized in spring 2009. A few months after the first swine flu cases were reported, rates of confirmed H1N1-related illness were increasing in much of the world. As a result, the World Health Organization declared the infection a global pandemic.

The pandemic was declared over in August 2010. Currently, H1N1 is still circulating in humans as a seasonal flu virus and protection against this strain was included in the seasonal flu vaccine for 2015-16. Another strain, H3N2 emerged in humans in 2011.

SYMPTOMS :

H1N1 flu signs and symptoms in humans are similar to those of other flu strains:

  •       Fever (but not always)
  •       Cough
  •       Sore throat
  •       Runny or stuffy nose
  •       Watery, red eyes
  •       Body aches
  •       Headache
  •       Fatigue
  •       Diarrhea
  •       Nausea and vomiting

H1N1 flu symptoms develop about one to three days after you’re exposed to the virus.

CAUSES :

Influenza viruses infect the cells lining your nose, throat, and lungs. The virus enters your body when you inhale contaminated droplets or transfer the live virus from a contaminated surface to your eyes, nose or mouth.

RISK FACTORS :

If you’ve traveled to an area where many people are affected by swine flu (H1N1 flu), you may have been exposed to the virus, particularly if you spent time in large crowds.

 

COMPLICATIONS :

  • Influenza complications include:
  • Worsening of chronic conditions, such as heart disease
  • and asthma
  • Pneumonia
  • Neurological  signs  and  symptoms,  ranging  from
  • confusion to seizures
  • Respiratory failure

 

TREATMENTS AND DRUGS : 

Laboratory testing has found H1N1 influenza A (swine flu) virus susceptible to the prescription antiviral drugs oseltamivir and zanamivir. Other antiviral agents (eg, amantadine, rimantadine) are not recommended because of recent resistance to other influenza strains documented over the past several years.

The usual vaccine for influenza administered at the beginning of the flu season is not effective for this viral strain. Also, other antiviral agents (eg, amantadine, rimantadine) are not recommended because of recent resistance to other influenza strains documented over the past several years.

Basic supportive care (ie, hydration, analgesics, cough suppressants) should be prescribed. Empiric antiviral treatment should be considered for confirmed, probable, or suspected cases of H1N1 influenza. Treatment of hospitalized patients and patients at higher risk for influenza complications should be prioritized.

High-risk groups are those who:
  • Are in a hospital, nursing home or another long-term care facility
  • Are younger than 5 years of age, particularly children younger than 2 years
  • Are 65 years and older
  • Are pregnant or within two weeks of delivery, including
  • women who have had the pregnancy loss
  • Are younger than 19 years of age and are receiving long-term aspirin therapy, because of an increased risk of developing Reye’s syndrome, a rare but potentially fatal disease that can occur when using aspirin during a viral illness
  • Are morbidly obese, defined as having a body mass index above 40
  • Have certain chronic medical conditions, including asthma, disease, or kidney, liver or blood disease
  • Are immunosuppressed due to certain medications or HIV
  • Are American Indians or Native Alaskans

 

LIFESTYLE AND HOME REMEDIES :

If you develop any type of flu, these measures may help ease your symptoms:
  • Drink plenty of liquids. Choose water, juice and warm soups to prevent dehydration.
  • Rest. Get more sleep to help your immune system fight infection.
  • Consider pain relievers. Use an over-the-counter pain reliever, such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others), cautiously. Also, use caution when giving aspirin to children or teenagers.
  • Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye’s syndrome, a rare but potentially life-threatening condition, in such children.
  • Remember, pain relievers may make you more comfortable, but they won’t make your symptoms go away faster and may have side effects. Ibuprofen may cause stomach pain, bleeding, and ulcers. If taken for a long period or in higher than recommended doses, acetaminophen can be toxic to your liver.

PREVENTION : 

The Centers for Disease Control and Prevention recommends flu vaccination for all people older than 6 months of age. An H1N1 virus is one component of the seasonal flu shot for 2014-15. The flu shot also protects against two or three other influenza viruses that are expected to be the most common during the flu season.

The vaccine will be available as an injection or a nasal spray. The nasal spray is approved for use in healthy people 2 through 49 years of age who are not pregnant. The nasal spray isn’t recommended for people who are older than 50, younger than 2, pregnant or allergic to eggs, or people who have asthma or a compromised immune system, or those who use aspirin therapy.

 

These measures also help prevent swine flu (H1N1 flu) and limit its spread:
  • Stay home if you’re sick. If you have swine flu  (H1N1flu), you can give it to others. Stay home for at least 24 hours after your fever is gone.
  • Wash your hands thoroughly and frequently. Use soap and water, or if they’re unavailable, use an alcohol-based hand sanitizer.
  • Contain your coughs and sneezes. Cover your mouth and nose when you sneeze or a cough. To avoid contaminating   your hands, cough or sneeze into a tissue or the inner crook of your elbow.
  • Avoid contact. Stay away from crowds if possible. And if you’re at high risk for complications from the flu — for example, you’re younger than 5 or you’re 65 or older,  you’re pregnant, or you have a chronic medical condition such as asthma — consider avoiding swine barns at seasonal fairs and elsewhere.
  • Reduce exposure within your household. If a member of your household has swine flu, designate only one household member to be responsible for the ill person’s  personal care.