Kerala reports 14 cases of Zika virus: A timeline of how the mosquito-borne disease spread
Transmitted by mosquitoes, Zika is a viral infection and the symptoms are similar to dengue including fever, skin rashes and joint pain. Additionally, infected people can transmit the virus sexually
A statewide alert was issued in all districts of Kerala on Friday following the detection of 14 cases of Zika virus in Thiruvananthapuram district. Kerala health minister Veena George has confirmed the infections.
The state had reported its first case of the mosquito-borne disease on Thursday when a 24-year-old pregnant woman was diagnosed with it. However, the government was was awaiting confirmation from the National Institute of Virology (NIV) at Pune.
Of the 19 samples sent from Thiruvananthapuram to NIV, 13 health workers, including doctors, are suspected to be positive for Zika, the health minister said.
The ongoing monsoon rains have turned the affected areas into "breeding ground for the mosquitoes", George told reporters on Friday. The mosquito-borne virus has been linked to shrunken brains in children and a rare auto-immune disease called Guillain-Barre syndrome.
What is Zika virus?
First identified in Uganda in 1947 in monkeys, Zika was later identified in humans in 1952. Transmitted by mosquitoes, Zika is a viral infection and the symptoms are similar to dengue including fever, skin rashes and joint pain. Additionally, infected people can transmit Zika sexually.
Sporadic cases have been reported throughout the world since the 1960s, but the first outbreak happened only in 2007 in the Island of Yap in the Pacific. In 2015, a major outbreak in Brazil led to the revelation that Zika can be associated with microcephaly, a condition in which babies are born with small and underdeveloped brains.
According to the Centre for Disease Control (CDC), severe disease requiring hospitalisation and deaths are uncommon. However, in rare cases, Zika may cause Guillain-Barré syndrome (GBS).
How did Zika start spreading
The first large outbreak caused by the Zika infection was reported from the Island of Yap in 2007. After years of sporadic reports in Africa, the two other major outbreak of the disease occurred in French Polynesia (2013-2014) and South America (2015-2016).
A timeline of the mosquito-borne Zika virus
1947: Scientists conducting routine surveillance for yellow fever in the Zika forest of Uganda isolated the Zika virus in samples taken from a captive, sentinel rhesus monkey.
1948: The virus was recovered from the mosquito Aedes africanus, caught on a tree platform in the Zika forest.
1952: The first human cases were detected in Uganda and the United Republic of Tanzania in a study demonstrating the presence of neutralising antibodies to Zika virus in sera.
1969–1983: The known geographical distribution of Zika expanded to equatorial Asia, including India, Indonesia, Malaysia and Pakistan, where the virus was detected in mosquitos. In Africa, sporadic cases occured, but no outbreak was detected and the disease in humans continued to be regarded as rare, with mild symptoms.
2007: Zika started spreading from Africa and Asia to cause the first large outbreak in humans on the Pacific island of Yap, in the Federated States of Micronesia. Prior to this event, no outbreak and only 14 cases of human Zika virus disease had been documented worldwide
2013–2014: The virus caused outbreaks in four other groups of Pacific islands: French Polynesia, Easter Island, the Cook Islands, and New Caledonia. The outbreak in French Polynesia, generating thousands of suspected infections, was intensively investigated. The results were reported to the World Health Organisation (WHO) on 24 November, 2015, and 27 January, 2016.
2 March, 2015: Brazil notified WHO of reports of an illness characterised by skin rashes in northeastern states.
From February 2015 to 29 April, 2015, nearly 7,000 cases of illness with skin rash were reported in these states. All cases were mild, with no reported deaths. Zika was not suspected at this stage, and no tests for Zika were carried out.
1 February, 2016: WHO declared that the recent association of Zika infection with clusters of microcephaly and other neurological disorders constituted a Public Health Emergency of International Concern.
Zika's passage to India
In India, Zika virus was first recorded in 1952-53. The country reported an outbreak in Gujarat in 2016-17. This was followed by major outbreaks in Rajasthan and Madhya Pradesh in 2018. In late 2018, 159 cases of Zika virus infection were reported in Rajasthan and 127 in Madhya Pradesh, according to a Lancet study.
Prior to this, three cases were detected in Bapunagar area in Gujarat's Ahmedabad district in May 2017. One case was also reported from Krishnagiri district on Tamil Nadu in July 2017.
The outbreak in India highlighted the spread of this disease beyond geographical barriers owing to the growing globalisation, increased travel and ubiquitous presence of its vector, the Aedes mosquito.
Any protocol that governments follow when Zika cases are reported?
Governments take mosquito control measures such as spraying of pesticides, use of repellents, etc. Because of the possibility of congenital abnormalities and sexual transmission, there is also focus on contraceptives.
The WHO requires countries to counsel sexually active men and women on the matter to minimise chances of conception at the time of an outbreak.
Zika virus prevention
Aedes 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.
For source reduction of mosquito breeding, it is 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. During outbreaks, spraying of insecticides should be carried out.
Is there any treatment for Zika virus
Zika has no treatment or vaccine. The symptoms of Zika virus are mild and usually require rest, consumption of plenty of fluids, common pain and fever medicines, the WHO said.
With inputs from agencies