ZIKA VIRUS: AN EMERGING THREAT TO HUMAN HEALTH NATIONAL AND GLOBAL SCENARIO

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A new emerging mosquito borne virus (Flaviviridae), first segregated in 1947 from a Rhesus monkey present in Zika forest of East African country Uganda, is the Zika virus. Its transmission is mainly by the bite of Aedes mosquitoes. In sub-Saharan Africa and Southeast Asia, there were occasional cases after first Zika virus emergence. The outbreaks of Zika virus occurred in 2007 in Micronesian Island, Yap and in New Caledonia, French Polynesia, the Cook Islands, and Easter Island between 2013 and 2014. There was a considerable increase in the cases of Zika virus in the Americas in 2015. There were 0.44 to 1.3 million victims of indigenous (autochthonous) Zika virus disease reported upto December 2015 making Brazil the most affected country.

A total of 41 countries and territories were undergone Zika virus outbreaks between 2007 and 2016. A locally acquired case of Zika virus without mosquito-borne transmission has been reported in one country (United States of America) that is likely to be by sexual contact and indirect local transmission has also been reported in six additional countries.

Local transmission has also been reported in two new countries Aruba and Bonaire in the week running up to 17 February 2016. Six countries/territories have reported an increase in the incidence of cases of microcephaly (Smaller head size than standard) and/or Guillain-Barré syndrome (GBS) following a Zika virus outbreak. Increased incidence of zika virus associated problems including microcephaly (Smaller head size than standard) and/or Guillain-Barré syndrome (GBS- a rare disease where muscle weakness and paralysis occur due to nerve cells death by a person’s own immune system) has been observed in the following six countries/territories (Colombia, Brazil, Suriname, El Salvador, Venezuela, and French Polynesia).

There is no case of Zika virus in Pakistan so far (WHO and Pakistan’s Ministry of National Health Services). But Pakistan has been facing the outbreaks of dengue fever since 2005 and 3,581 cases and 11 deaths reported in Karachi in 2015. Transmission of Zika virus to people is through bite of an infected Aedes mosquito, mainly Aedes aegypti in tropical regions. Dengue, chikungunya and yellow fever are also transmitted by the same vector mosquito. This indicates the probable chance of Zika virus transmission in Pakistan due to availability of vector mosquito.

Sexual partner can take Zika virus from infected person through sex. Pregnant woman can pass virus to the fetus but there is no report of transmission through breastfeeding. There is strong chance that Zika virus may contract via blood transfusions.

The time from exposure to development of symptoms of Zika virus disease is not clear, but a few days may be. Fever, conjunctivitis (red eye), skin rashes, muscle and joint pain especially in the small joints of the hands and feet with possible swelling, malaise, and headache are the signs and symptoms of the disease. These symptoms are not severe lasting for 2-7 days.

Pregnant women could be infected with Zika virus probably by the bite of infected mosquitoes as the rest of the population. Many women may think that they do have Zika virus because the symptoms might not developed in them. The chance of disease development is 1 out of 4 Zika virus infected people and those showing signs and symptoms, illness is not severe.

Research has been conducted to provide evidence of Zika virus effects on fetuses. A direct relationship between microcephaly disorder in newborns and Zika virus infections in the country’s northeast was developed by the Ministry of Health of Brazil on 28th November 2015. Infection during the first trimester of pregnancy can lead to microcephaly and malformations risks according to result of research carried out by Brazilian authorities. The Potential complications of Zika virus disease in northeast Brazil is Guillain-Barré syndrome.

Symptoms and recent history (e.g. residence or travel to an area where Zika virus is known to be present) are the two main factors which can lead to the diagnosis of infection with Zika virus. Confirmation of Zika virus infection can only be performed by laboratory testing through detecting viral RNA in the blood or other body fluids, such as urine or saliva.

There is no vaccine or specific treatment for Zika virus infection. Therefore, treatment for everyone, including pregnant women, is directed at alleviating symptoms. PAHO/WHO urges women who are pregnant or planning to become pregnant to seek prenatal care to receive information and monitoring of their pregnancy and to follow their doctors’ recommendations.

Significant risk factors for Zika virus infection are mosquitoes and their breeding sites. Reducing mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people can lead to better prevention and control of mosquito borne diseases. This can be done by:

  1. Making insect repellent use a daily routine
  2. Preferring light-colored clothes covering most of the body and wearing full sleeves
  3. Applying physical barriers through window screens, closed doors and windows
  4. Sleeping under mosquito nets during the day and night making personal protection possible
  5. Emptying, cleaning or covering containers such as buckets, drums, pots etc. regularly where water can accumulate
  6. Cleaning or removing used tyres, flower pots and roof gutters which are mosquito breeding sites
  7. Providing special attention to young children, the sick or elderly as they may not be able to protect themselves adequately
  8. Advising health authorities during outbreaks for spraying of insecticides in the area
  9. Using insecticides recommended by the WHO Pesticide Evaluation Scheme as larvicides to treat relatively large water bodies
  10. Taking the basic preventive measures described above while travelling to protect ourselves from mosquito bites
  11. Applying repellents which contain DEET (N, N-diethyl-3-methylbenzamide), IR3535 (3-[N-acetyl-N-butyl]-aminopropionic acid ethyl ester) or icaridin (1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-1-methylpropylester)

Currently there is a running project titled “Metagenomics of Mosquito Vectors and Abundance of Mosquito-borne Pathogens in different Agro-Geoclimatic Areas of Punjab, Pakistan”  under the kind supervision of Dr. Muhammad Sohail Sajid and his team  in the Molecular Parasitology Laboratory, Faculty of Veterinary Science, University of Agriculture, Faisalabad which will help in the establishment of  reference colonies of medically significant mosquitoes, identification of mosquito vectors and mosquito-borne pathogens through molecular tools (PCR) for risk analysis mapping and development of genome wide RNAi screen to identify new and novel targets to block mosquito feeding and pathogen transmission. All this is an attempt to understand the distribution of mosquitoes and mosquito-borne diseases in selected agro-geoclimatic zones of Punjab, Pakistan.


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Published in: Volume 08 Issue 38

Short Link: http://www.technologytimes.pk/?p=18443