Rezultati programa monitoringa bolesti Zapadnog Nila Republici Srbiji u 2022. godini

Abstract

Poslednjih nekoliko godina je u Srbiji konstanto prisutna cirkulacija virusa Zapadnog Nila (VZN). U humanoj populacije su zabeležene veće ili manje epidemije počev od 2012. godine pa sve do danas. Veterinarska služba u Srbiji je od juna 2022. godine pokrenula godišnji nacionalni program monitoringa VZN, koji je predstavljao nastavak godišnjih programa monitoringa počev od 2014. godine. Program je finansiran od strane Uprave za veterinu, a na terenu ga je sprovodila veterinarska služba u saradnji sa entomolozima i ornitolozima. Cilj programa je bila rana detekcija prisustva VZN na nekom području i pravovremeno alarmiranje humane zdravstvene službe i lokalnih samouprava radi sprovođenja mera kontrole (suzbijanja komaraca) i informisanja stanovništva. Program monitoringa se zasnivao na indirektnom i direktnom praćenju prisustva VZN u prirodi. Indirektno praćenje virusa se vršilo serološkim testiranjem konja na prisustvo IgM antitela i sentinel teladi uzrasta 6 do 8 meseci (oteljenih nakon sezone vektora u prethodnoj godini) na IgG antitela protiv VZN kao potvrda akutne infekcije i cirkulacije VZN. Direktno praćenje se vršilo ispitivanjima zbirnih uzoraka komaraca i uzoraka divljih ptica na prisustvo VZN molekularnim dijagnostičkim metodama u aktivnom i uzoraka na bolest suspektnih konja u pasivnom nadzoru. Broj uzoraka za ispitivanje je određen po okruzima na osnovu visine rizika od pojave infekcije VZN. U periodu jun-septembar 2022. na području R. Srbije je po programu ispitano 1853 krvnih seruma konja od čega je kod 25 (1,30%) utvrđeno prisustvo IgM antitela. Ista je bila u uzlaznoj liniji sa povećanjem aktivnosti vektora i u junu je kod 0,9% (4/437), u julu kod 2,0% (10/490), u avgustu kod 1,9% (9/468) i u septembru kod 0,9% (4/458) konja utvrđen pozitivan serološki odgovor. Broj okruga u kojima je detektovana serokonverzija je iznosio 2 u junu, 3 u julu, 5 u avgustu i 3 u septembru. U istom periodu je na području visoko rizičnih okruga (14/25) kod 1740 ispitanih teladi utvrđeno prisustvo IgG antitela protiv VZN kod 8,0% životinja (140/1740), odnosno kod 11 (2,7%), 34 (6, 9%), 46 (10,6%) i 49 (11,8%) sentinel teladi, na području 4/14, 7/14, 9/14 i 9/14 okruga u junu, julu, avgustu i septembru U direktnom praćenju prisustva VZN ispitano je 792 zbirnih uzoraka (pulova) komaraca i VZN je potvrđen u 34 (4,3%) uzorka. Prevalencija VZN u komarcima je rasla od negativnog nalaza u junu (0/160), prvog pozitivnog nalaza 5,9% (19/320) u julu, pozitivnih nalaza 4,5% (7/156) u avgustu i 5,1% (8/156) u septembru. Pozitivni uzorci komaraca na VZN su detektovani u 9 od 25 okruga: > 20% pozitivnih od ispitanih uzoraka je utvrđeno na području Beograda, 19,15% u Srednjebanatskom, 18,37% u Južnobanatskom, 8,7% u Sremskom, 8,33% Južnobačkom, 6,0% u Šumadijskom, 4,17% u Severnobanatskom, 4,08% u Severnobačkom i 2.0% u Zapadnobačkom okrugu. VZN je utvrđen u uzorcima 11/52 (21,1%) uginulih divljih ptica sa područja 7 okruga, kao i u 14 (3,7%) od 379 ispitanih uzoraka ždrelnih briseva živih divljih ptica na području 4 okruga. Program monitoringa VZN se tokom 2022. godine pokazao kao uspešan i svrsishodan i neophodno ga je nastaviti i unaprediti u narednom periodu u cilju pravovremene zaštite zdravlja ljudi i životinja.

The constant circulation of West Nile virus (WNV) has been detected in the last few years in Serbia. Bigger or smaller epidemics have been reported in human population in Serbia since 2012, until today. The veterinary service in Serbia launched the yearly national program for WNV monitoring in June 2022, and it was a continuation of the yearly monitoring programs conducted since 2014. The program was funded by the Veterinary Directorate, and it is implemented on the field by veterinary service in collaboration with entomologists and ornithologists. The main objective of the monitoring program was the early detection of the presence of WNV in a certain area, and timely alerting of human health services and local governments in order to control the mosquito population and to inform the local communities. The monitoring program was based on the direct and indirect monitoring of the presence of WNV in the environment. Indirect monitoring of virus presence was performed by serological testing of horses on the presence of anti-WNV IgM antibodies, and sentinel calves aged 6 to 8 months (calved after the vector season in the previous year) for the presence of anti-WNV IgG antibodies, as the confirmation of acute infection. Direct monitoring of the WNV presence in nature was done by molecular testing of WNV presence in pooled mosquito’s samples and in wild birds in active surveillance and by testing the samples of clinically suspected horses in passive surveillance. The number of tested samples was defined at the level of each district of the Republic of Serbia in relation to the risks of WNV infection. In the period of June-September 2022 in Serbia, according to the program, 1853 blood sera of horses were tested, and seroconversion (IgM antibodies) was detected in 25 (1.3%) horses. The seroconversion was in an upward line in concordance with the increase in the activity of the vectors, thus positive serological responses were determined in June in 0.9% (4/437), in July in 2.0% (10/490), in August in 1.9% (9/468), and in September in 0.9% (4/458) of tested horses. The number of districts where the positive horses were detected was: 2 in June, 3 in July, 5 in August and 3 in September. In the same period, in high-risk districts (14/25), in 1740 examined calves, the presence of IgG-anti-WNV antibodies was determined in 8.0% of animals (140/1740), i.e. in 11 (2.7%), 34 (6, 9%), 46 (10.6%) and 49 (11.8%) sentinel calves, in the 4/14, 7/14, 9/14 and 9/14 districts in June, July, August and September. In direct monitoring of virus presence, 792 pooled mosquito samples were tested from June to September 2022, and WNV was confirmed in 34 (4.3%) samples. The prevalence of WNV in mosquitoes increased from a negative finding in June (0/160), to the first positive finding 5.9% (19/320) in July, and positive findings 4.5% (7/156) in August and 5.1% (8/156) in September. Positive mosquito samples were detected in 9 out of 25 districts of Serbia: > 20% positive out of the tested samples were detected in the Belgrade area, 19.15% in the Central Banat, 18.37% in the South Banat, 8.7% in the Srem, 8.33% in the South Bačka, 6.0% in the Šumadia, 4.17% in North Banat, 4.08% in North Bačka and 2.0% in West Bačka district. WNV was determined in 11 samples out of 52 (21.1%) dead wild birds from the area of 7 districts, as well as in 14 (3.7%) out of 379 examined samples of pharyngeal swabs of live captured wild birds in the area of 4 districts. WNV monitoring program during 2022 proved to be successful and meaningful and it is necessary to continue and improve it in the forthcoming period in order to ensure the timely protection of human and animal health.