Last week, when Ahmedabad mayor Gautam Shah and senior officials of the city corporation visited Gopalnagar in western Ahmedabad, citizens were surprised. “We later found out that the visit was because we had a Zika case in our neighbourhood,” said Babubhai Desai, a teacher living in the locality. “They posed for photographs for the press, sprayed some powder and left.”

Three Zika cases were detected in Gopalnagar and Bapunagar in Ahmedabad since November last year. None of the infected people had traveled far away, which indicates that the virus was picked up locally. The presence of local Zika virus transmission indicates that people in the area might still be vulnerable to infection.

One of the ways that Zika is transmitted is through the bite of the Aedes mosquito, the same disease vector that spreads dengue and chikungunya. There is a large population of Aedes aegypti mosquitoes in Ahmedabad and plenty of disease to go with it. Ahmedabad has already recorded 137 cases of chikungunya between January and May this year. The city had only two cases in the same period last year. Ahmedabad corporation has recorded the highest number of chikungunya cases among all districts of Gujarat. According to the data from the Gujarat health department, 243 people have tested positive for chikungunya this year.

“There is nothing to panic about,” said Dr Bhavin Solanki, medical officer of health for Ahmedabad. “Most of the cases were of relapse which means that people who had chikungunya in the past were getting it again because of low immunity.”

However, infectious disease specialist Dr Om Shrivastav from Mumbai said that chikungunya cases cannot be reactivated. “If there are cases in the community, it only means that the virus is in circulation and the vector responsible for spreading the virus is present,” he said.

Breeding mosquitoes

Bapunagar is a neighbourhood of small homes inhabited by daily wage labourers. Between the small homes are even smaller bylanes. “Our problem is not just mosquitoes but also water,” said Pratap Marwari who lives here. “Most times the sewage lines get mixed with the water supply and we get contaminated water, which we have to drink.”

Marwari’s concern about water contamination is also a worry about mosquito breeding. Most women in the locality heat the water and store it in containers outside their homes since the water supply is irregular. These containers are common breeding sites for mosquitoes. Surveillance carried by the Ahmedabad municipal corporation showed that six percent of water containers they checked in Bapunagar were breeding mosquitoes. The team screened about 59,000 water containers.

Even in Gopalnagar, the city corporation conducted a drive to control mosquito breeding sites, which residents did not quite understand. “They came and checked the water containers,” said Seeta Hari Bahadur Thapa, who has a three-month old daughter. She gestured at the many water containers stacked outside her one-room house.

“They didn’t tell us about mosquitoes, they just saw the containers and said we should keep them clean,” Thapa said.

A few homes away from Thapa lives Pratiksha Gaikwad who was not visited by corporation officials. “I don’t know about malaria,” said Gaikwad. “No one has ever come to my house from the corporation.”

While Zika, dengue and chikungunya are transmitted by Aedes mosquitoes, malaria is transmitted by female Anopheles mosquitoes.

Under-reporting

Government numbers of dengue, malaria and chikungunya cases may be an underestimation, say health activists and and doctors in the state. The Ahmedabad Municipal Corporation’s health department officials said that doctors from private hospitals are required to notify dengue, malaria and chikungunya cases to them.

Dr Chandulal Kathiria, associate professor from department of medicine at Sharadaben Hospital, said that most doctors do not notify cases to the government. “There is a lot of under-reporting of cases,” said Kathiria.

Kathiria added that patients from lower socioeconomic backgrounds may not be able to afford blood investigations. “If they get better, they do not get tested and we may never really know what viral fever they were suffering from,” he said.

Under-reporting disease cases affects vector-control activities since the real burden of diseases is not visible and so the urgency of the action needed is not correctly assessed.

Like chikungunya, the number of malaria cases has also increased dramatically this year, according to data from the Ahmedabad Municipal Corporation. There have been 1,809 malaria cases between January and May, compared to 1,346 cases reported in the same period last year.

“We are seeing several malaria cases, especially from areas where there is construction activity,” said Dr Pragnesh Vachharajani, a general practitioner from Ahmedabad. Construction sites with large containers where water collects are often good breeding sites for mosquitoes spreading dengue and malaria.

Across Gujarat there have been 4,450 malaria cases recorded between January and April, while there were 4,333 last year in the same period last year.

Officials said that Ahmedabad records the most cases because reporting of diseases is comparatively better compared to other districts. The higher population density also leads to more infections.

Unusual viral fever cases

Beside treating cases of malaria and dengue, Kathiria and his colleagues are treating what they classify as “unusual fevers”. These, they find, are often self-limiting cases where the fever subsides on its own. However, the doctors have not been able to identify the cause of these fevers.

“These fevers could also be cases of Zika but we can’t tell as we were not testing them for Zika,” said Kathiria.

“We suspect viral fever, when the patient comes with high grade fever and rashes,” said Dr Kamlesh Upadhyay, professor of medicine at BJ Medical College in Ahmedabad. “Some viral fever cases we are treating could also be Zika.”

General practitioner Vachharajani echoed this view. “Everything cannot be proved in the laboratory,” he said. “Also, as far as viral fevers are concerned including dengue and chikungunya, we have to give symptomatic treatment,” he said. “In such a situation, we don’t emphasise blood investigations as the cost of testing may not be justified.”

More than four months after the first Zika case was confirmed, the World Health Organisation made a public announcement about the presence of the virus in Ahmedabad. Following this announcement, doctors in both government and private hospitals in Ahmedabad say that they will start screening fever patients for Zika as well as other infections and send their blood samples to laboratories designated to test for Zika. In the meantime, with the monsoon arriving, they are expecting to have their hands full with many more cases of mosquito-borne diseases.

This reporting project has been made possible partly by funding from New Venture Fund for Communications.