Re-emergence of Zika virus

Zika virus infection has been reported from Kerala. Eighteen cases, including in health care workers have so far been reported. The first case of Zika virus in the state was detected on Thursday after a 24-year-old pregnant woman near Thiruvananthapuram tested positive for the disease. The rising cases have put the state on a high alert.

Here is a quick review of salient facts about Zika virus disease.

  • Zika virus derives its name from the Zika forest in Uganda, where it was first identified in 1947 in monkeys. It was then identified in humans in 1952. The first recorded outbreak of Zika virus disease was reported from the Island of Yap (Federated States of Micronesia) in 2007. This was followed by a large outbreak of Zika virus infection in French Polynesia in 2013 and other countries and territories in the Pacific.
  • Causative agent: Zika virus (genus Flavivirus)
  • Transmission: Zika virus is transmitted by Aedes aegypti mosquitoes, which bite during the day. The virus can be passed from a pregnant woman to her fetus and through unprotected sex. It may also spread through blood transfusion.
  • Incubation period: 3-14 days
  • Symptoms: Most people are asymptomatic or have mild symptoms such as fever, rash, conjunctivitis, muscle and joint pain, malaise or headache lasting for 2–7 days.
  • Complications: Zika virus infection during pregnancy can cause microcephaly and other congenital malformations (congenital Zika syndrome) including stillbirths, miscarriages. Zika virus is a trigger of Guillain-Barré syndrome.
  • Diagnosis: RT PCR (polymerase chain reaction) and virus isolation from blood samples. Diagnosis by serology is not recommended.
  • Treatment: There is no specific treatment. Supportive care includes plenty of rest, adequate fluid intake, symptomatic treatment of pain and fever. Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen should be avoided.
  • Prevention: There is no vaccine yet for Zika. Hence, prevention of Zika is by protection against mosquito bites such as using insect repellent, covering as much of the body as possible with long, light-colored clothing, eliminating places where mosquitoes can breed and putting screens on windows and doors. Do not allow water to collect around homes or other areas, which are breeding sites for the mosquito.

The most recent outbreak of Zika occurred in Brazil in 2015-16. It then spread to South and North America, several Pacific islands and also Southeast Asia. Evidence linking it to birth defects and neurological problems prompted the World Health Organization (WHO) to declare it a Public Health Emergency of International Concern in 2016. The 2016 Rio Olympics were held in Brazil under the shadow of this outbreak.

The current cases appear to be a contained outbreak. However, Zika is not new to India. In 2017, three laboratory-confirmed (RT-PCR) Zika virus infection cases were reported in Gujarat and also in Tamil Nadu.

Most of the resources have been dedicated to combating Covid-19 since it was first declared a pandemic in March last year and rightly so. However, the re-emergence of these Zika cases suggest a low level of transmission and do point out the need for active surveillance for other infectious diseases as well before they become a major public health problem. This surveillance has to be continuous and not episodic given the climate that is favorable to vector-borne diseases. Just as we have seen the SARS-CoV-2 evolving into more infectious strains, so could the Zika virus.

All cases of acute febrile illness should be tracked and treated. Dengue or Chikungunya-like symptoms of fever with a skin rash or joint pains, with red eyes, should not be ignored. Such cases could be Zika. All three viral infections share a common vector, the Aedes mosquito.

The public should be educated about the disease including its preventive measures. At the same time, they should be assured that there is no need to panic.

(Source: WHO Zika Virus Fact Sheet 2018; NCDC Fact sheet on Zika Virus Disease Updated 3rd February 2016)

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