West Nile Fever: Why Belgrade Sprays for Mosquitoes at Dawn
The first two lab-confirmed cases this season came from Belgrade. Batut's director sees no reason for concern, but the city moved mosquito spraying to dawn.
Do the first two West Nile fever cases of the season mean we should be worried? The director of the “Batut” Institute says no, though she names two times of day worth avoiding. At the same time, the city has pushed its mosquito spraying back to three in the morning.
On August 5, the first two laboratory confirmed cases of West Nile fever in the 2026 surveillance season were registered. Both patients are from Belgrade, aged 75 and 82. Both were hospitalized at the Clinic for Infectious and Tropical Diseases in Belgrade after developing the neuroinvasive form of the disease. The cases were confirmed by the National Reference Laboratory for Arbo Viruses and Hemorrhagic Fevers at the Torlak Institute and by the Belgrade City Institute of Public Health.
The director of the Institute of Public Health of Serbia “Dr Milan Jovanovic Batut”, Prof. Dr. Verica Jovanovic, first commented on the cases on August 7:
At this point we have no reason for concern, because infections caused by the West Nile virus will appear every season. What matters most for all of us is avoiding the times of day when mosquito bites are most intense, at dusk and at dawn.
Infections with this virus occur in Serbia from early June through the end of September, so new cases are expected in the coming weeks. The virus is carried by Culex mosquitoes, which pass it from birds to humans.
When do mosquitoes bite the most?
At dusk and at dawn. Those are the two windows that come up in every recommendation, and they decide whether an evening walk along the river or a morning run on the embankment even makes sense.
Jovanovic also pointed out that the cases detected so far tend to involve the more severe forms of infection, inflammation of the brain or its membranes, particularly in people with chronic illnesses. Mild infections often go unnoticed and never reach a laboratory, so the count of two confirmed cases reflects the severe cases, not the total number of people infected.
Spraying now runs from 3 to 7 a.m.
On August 7, the City Cleaning public utility (JKP Gradska cistoca) treated adult mosquitoes with ground and water based equipment, from 3 to 7 a.m. The treatment covered:
- Zvezdara Forest and the New Cemetery
- Plitvicka Street along the Banjica Stream and Banjica Forest
- the Central Cemetery, Banjica, Stepa Stepanovic and Kumodraz
- Bele Vode, Batajnica and the Sangaj neighborhood
- Altina, Plavi Horizont, Skolsko Dobro and Radio Far
The operation depends on the weather, as the city explicitly stressed.
Treatments will be carried out only if weather conditions allow, meaning no rain, an optimal temperature and appropriate wind strength.
The shift in schedule is worth noting. On the same night the first two cases were confirmed, August 5, crews worked from 10 p.m. to 2 a.m. and covered:
- New Belgrade: Usce, Staro Sajmiste, blocks 19a, 44, 45, 70, 70A, 71 and 72, Belvil and Studentski Grad
- Zemun: upper and lower Zemun, Kalvarija, Sava Kovacevic, Sutjeska and Nova Galenika
Two days later, the time slot moved five hours earlier, landing exactly in the part of the day Batut flags as risky: dawn.
The products used for thermal and cold fogging are registered with the Ministry of Environmental Protection and listed on the Provisional List of Biocidal Products. Beekeepers have been advised to protect their hives during treatments.
Five things you can do today
The Batut Institute’s recommendations come down to a few steps I’ve tested in daily use, and none of them take more than half an hour:
- Apply repellent to exposed skin before every evening outing
- Wear loose, light colored long sleeves and trousers, since mosquitoes bite through tight fabric
- Put mosquito netting on windows, doors and around the bed; air conditioned rooms already have far fewer mosquitoes
- Empty every container of standing water once a week: flowerpot saucers, pet bowls, buckets, barrels and cans
- Remove old tires and other objects from the yard where rainwater collects
If there are too many mosquitoes in the neighborhood, complaints go to the City of Belgrade Service Center at 11-0-11, on weekdays from 7 a.m. to 10 p.m. and Saturdays from 8 a.m. to 2 p.m.
We covered protective measures in more detail in “West Nile Fever in Serbia: 6 Mosquito Protection Measures”, and they have not changed since.
The season runs through the end of September, so treatments will continue whenever the weather allows. The “Batut” Institute marks 102 years of work this year, and its advice is the same as in past seasons: as soon as symptoms consistent with the neuroinvasive form of the disease appear, see your doctor right away, don’t wait for it to pass on its own.
