Samples of mosquitoes collected to detect Zika virus; genome sequencing underway to identify lineage
PUNE To keep a tab on the spread of the Zika virus, mainly spread by the Aedes mosquito, the district administration has collected samples of mosquitoes along with blood smear samples to identify if the infection could be spread via mosquitoes in the region.
The administration has also collected samples for genome sequencing to identify the lineage of the virus and to find how dangerous it could be for pregnant women. The central team, which met with concerned officials on Wednesday, will conduct a site inspection at Belasar village, Purandar taluka, on Thursday.
Dr Pradeep Awate, state surveillance officer who was part of the central team’s meeting with the district officials said, “We have sent samples of mosquitoes to identify if there are any infected mosquitoes. We will also be doing genome sequencing to identify the lineage. There are primarily two lineages, Asian and African, to find if pregnant women are more susceptible. As of now we are collecting samples of pregnant women in the village and from nearby villages for testing. The probable causes of the spread of the virus could be the underground tanks which could be breeding ground for the Aedes mosquito, which is the primary vector of the virus and also other viruses.”
He also added that the probable source of infection could be traders who come to the villages with agriculture fields mainly producing tomatoes and pomegranates. Awate said, “Traders from across the country including Kerala have been visiting the villages for trading purposes and it could be that one of the infected persons could have carried the infection to the village. About 80% of those infected with Zika virus remain asymptomatic and so it would be difficult to know if an infected person had indeed travelled. However, this is just a possibility. We do not know for sure what is the source of infection in this case.”
Kerala has been reporting a high number of Zika virus cases and as of July 21, the state reported 41 confirmed cases.
The NIV team which visited the Belaras village, and of the five initial samples sent, three tested positive for chikungunya. Once the outbreak was reported on July 14, a NIV team under leadership of Dr Yogesh Gurav, team leader of Arbovirus division, visited the village On July 27. The NIV team visited Belsar, Shivri, Malshiras and Supe (Khurd) villages. The team visited the residential and non-residential areas and checked vector breeding in the water holding containers. NIV Team collected 51 blood samples of suspected Chikungunya cases during their visit, of which one sample tested positive for Zika. The Zika positive sample was also positive for Chikungunya Real time PCR and Chikungunya IgM ELISA.
The first positive case of Zika virus was reported in the village, which was a 50-year old lady. She tested positive for both Zika and Chikungunya. She has symptoms like fever, joint pain, headache, eye pain and petechial haemorrhages. She has no travel history. Her daughter, a 25-year old, tested positive for Chikungunya.
In its report to the central team the district administration pointed out that one of the probable reasons is increased Aedes larval density. The report states Belsar village has water supply through a water supply scheme, but as the water supply scheme is too old due to some technical glitch villagers get tap water supply once in three days. This forces villagers to store water for domestic purposes. These water containers are coverless. Many households have underground tanks for water storage. These tanks are also devoid of any cover.
As of August 4, of the 152 samples sent to NIV, five tested positive for dengue, 63 for chikungunya, 15 for dengue and Chikungunya and one for Zika and Chikungunya, while 41 have tested negative for any of the infections and 27 reports are yet to be declared.
Some of the ongoing measures in Belasar and the neighbouring villages are house-to-house surveillance, which includes identification of cases within a five-km radius of the ground zero village, Belsar. In addition, a village cleanliness drive, capacity building of village volunteers for proactive entomological surveillance, normalisation of village water supply and health education about Zika and the necessity to use appropriate contraceptives for eligible couples is underway. Also entomological surveillance is underway, in which a house-to-house team does a daily assessment of the Aedes larval density through different indices.
In view of the high risk that the virus poses to the pregnant women, samples of all pregnant women are being sent to the NIV for testing, along with the high risk relatives of these pregnant women. Bed nets and creams have been provided to all the pregnant women for protection.
Pune city has over 33 thousand pregnant women, PMC cautions them to get tested in case of any symptoms
In the past four months, April to July, PMC has recorded 33,000thousand pregnant women who are in different trimesters, said a PMC official. As the first Zika virus cases are reported in Pune district, the Pune Municipal Corporation (PMC) has cautioned those with any symptoms, especially those who have travelled to any infected places to get tested. Dr Sanjeev Wavare, assistant health officer at PMC said, “The ongoing action like surveillance and fogging and destruction of Aedes mosquitoes larvae will be continued. However, if anyone who has symptoms of Zika virus which are mainly fever, rash, headache, joint pain, conjunctivitis (red eyes) and muscle pain, then they must get themselves tested at any private lab or even a PMC hospital”