Complicated epizootic situation on classical swine fever in Ukraine was observed in 1993-1996. In 1993 on the territory of 
our country there were registered 36 affected areas, in 1994 – 51 and in 1995 – 21. Only a few cases were registered in 1996. 
Since classical swine fewer appeared in the United States and then spreaded out to Europe and other parts of the world, it caused 
enormous  losses  for  the  economy  and  to  the hog  industry  in  particular.  Currently  the disease is  endemic  for  the  most  of  the 
countries of Eastern Europe, Central and South America and for South East Asia. In 1997–1998 the disease was registered in

Netherlands, in 2000 in UK, in 2006 in Germany (particlularly in 2009 on wild boars), in 2012–2013 in Latvia. In 2014 the 
disease was registered in Colombia with 14 outbreaks, in Latvia with 51, in Mongolia 3 and in Russia 4 outbreaks. In 2015 the 
disease was registered in Mongolia (two outbreaks), Russian Federation (3), Latvia (9), Colombia (12) and Ukraine on wild boars 
(1 outbreak in the Kiev region).  
Until nowadays such countries as Denmark, Norway, Sweden, Finland, Luxembourg, Hungary,  Ireland and USA are the 
safest with regard to the classical swine fever.  
The main source of the pathogen are sick animals, pigs with latent infection and recovered domestic and wild pigs, which 
are  infected  with  virus  (means  persistence  of  virus).  Remaining  undetected  in  the  General  herd,  those  pigs  are  particularly 
dangerous in spreading disease and the maintenance of the epizootic. Important is that all age groups and breeds of the pigs are 
susceptible to the classical swine fewer.  
Under the natural conditions infection of pigs occurs alimentary, aerogenic, contact- conjunctival and genital way. In the 
case of infection of pigs with virulent strains of the virus, it is mainly detected in blood and tissues. Infected animals allocate 
pathogen with saliva, urine, feces, lacrimal nazalnam and secrets into the environment. Virus isolation occurs until the death of 
the animal. In case of infection of pregnant sows (not vaccinated) with weakly  virulent strains, especially in the first half of 
gestation, transplacental infection of the fetus occurs. This ends in abortion or the birth of the dead (mummified) or weak piglets. 
These pigs may not have clinical signs of the disease, but they are able to spread the virus for several weeks or even months, 
predetermining virus infection status of the classical swine fewer.  
The spread of the virus from one farm to another is possible in case of the movement of infected pigs in the incubation 
period or pigs with latent infection (persistence of virus). Quite dangerous in this case is road transport. The transport of pigs over 
long distances can lead to loose contacts, in this case the situation is complicated if the infection occurs by low virulence strains. 
Due to the slow spread of this virus infection may occur and be undetected for weeks and months. The transport of pregnant sows 
to another farm may cause the entry of virus after farrowing in this farm and therefore the appearance of the pigs, which will be 
virus carriers and may lead to delayed diagnosis. The researchers point of view is that among piglings on farms can circulate 
pathogens with reduced virulence. Sows transmit the virus to pigs transplacental. Pigs imported from such farms for reproduction 
are the sources of the pathogen.  
Entry of the virus in safe areas and for the long distances is also possible with pork or pork products. Pigs can get infected in 
case of feeding them without a heat treatment slops, waste from slaughterhouses and meat processing plants.  
Specialists of veterinary medicine or artificial insemination technicians can carry the virus with contaminated instruments. The use 
of single needle, tools treatment of animals in case of virus-carrier animals creates a greater risk of recontamination.  
Confirmed  was  the  spread  of  virus  between  areas  with  forced  ventilation,  which  are  in  close  distance  from  each  other. 
Mechanical carriers of the virus can be people, dogs, cats, poultry and the like.  
Therefore,  pigs  with  latent  infection  is  the  most  important  reservoir  of  the  virus.  On  the  second  place  is  pork  and 
manufactured from meat of infected animals pork products, which are kept in the refrigerator processing plants in chilled state. 
These represent a potential risk for farms that use the waste of slaughter-houses for pigs feeding. Pigs in the incubation period 
and the sow-virus carriers belong also to one the main sources of infection.  
Latently infected wild boars is also a reservoir of the virus. They can infect domestic pigs through the feed chain or during the 
contact of sows before insemination or artificial insemination. The secretion of estrogen at this time contributes the attraction of the wild 
boars, including those, which are infected with the pathogenic agent of classical swine fever, and in the process of mating the infection of 
sows. For these reasons, some researchers suggest the possibility of natural circulation for this disease.  
The possibility of contact with wild pigs belongs to the reservoir of the classical swine fewer virus. This reason only may 
result in the outbreak of the disease. Thus the termination of vaccination in our country, where the private households contains 
56%  of  the  swine  livestock  is  premature decision.  Given these  circumstances,  abolition  of  the  disease is impossible.  For the 
classical swine fever wild bigs swine is recognized reservoir of this virus. Outbreak of the classical swine fever among wild pigs 
at the beginning of 2015 is only a confirmation of this thesis. Thus, in Ukraine the main measurement to combat classical swine 
fever belongs to a mass vaccination of pigs against this disease. Through such activities in our country at present the disease is 
sporadically  recorded  among  wild  pigs.  Obviously,  completely  abandon  vaccination  of  pigs  against  classical  swine  fever 
currently, would be unreasonable due to economic considerations. This could lead to an increase in the incidence of disease and 
consequently to significant economic losses. 
Key words: classical swine fever, transboundary іnfection, epіzootic situation, mechanisms of persistencia, latent іnfection, 
wild boar, the vaccine.