Control and prevention.
The elimination of Isospora suis from a farm can be really complicated due to the high environmental resistance of the oocysts, which can survive outside the host for months.
To control isosporosis in commercial farms, the combination of good hygiene and management practices, in addition to a high biosafety is essential, since the use of a broad spectrum of coccidicide has not proven to be not completely effective.
Taking into account the characteristics of neonatal pig coccidiosis given in the two previous articles, some practices to limit the infestation can be established.
Importance of transmission routes
The most important transmission route in a farm is the transmission of the infection from a litter of piglets to an adjacent one (not within litters in the same cubicle). Therefore, the environment (and not the sow) is the main source of the infestation.
Once the parasite is established on a farm, it is transmitted from one generation of piglets to the next via contaminated farrowing pens.
Although the sow tends to excrete oocysts intermittently and does not play an important role in the transmission and persistence of I. suis, it is convenient to remove the feces daily from the cubicles.
The oocysts are resistant to most disinfectants, however, any disinfection program which includes hot water washing (>70ºC) reduces the amount of oocysts in the environment and therefore, decreases the transmission and severity of the disease. Nonetheless, it does not eliminate the disease completely.
It has also been observed that all in/all out practices in maternity wards contribute to reduce the parasites, especially if the time between the output of a litter and the entrance of the following lasts a few days. Furthermore, it is important to clean the entire room at once instead of cubicle by cubicle, as it allows a homogeneous and simultaneous reduction of ooquists in all the stockyards.
The avoidance of the main transmission route (between litters) is an important measure to limit parasites. For this reason, it is necessary to implement management measures to limit workers’ access to the infested cubicles and pest control programs, since insects, rodents and birds can act as mechanical carriers.
Another significant factor that facilitates the transmission of oocysts from one batch to another is to apply the cross-fostering of piglets during the first 24 hours post-farrowing.
Straw flooring entails greater contact of piglets with feces, facilitating the transmission of the parasite.
Flooring type of the cubicles is also related to the level of infestation of piglets, for example, plastic is easier to clean than the metal, thus farms with plastic floors can reach lower prevalence of I. suis easier. Floors with a higher perforated area (slat) allow less contact of the animals with their feces, so the probability of ingesting infective oocysts is reduced.
Usage of medication
On one hand, the metaphylactic treatment of piglets with coccidiostats reduces oocyst excretion, decreasing the number of sick or dead animals and the effect of the disease on productive parameters. On the other hand, the use of drugs contributes to the appearance of parasitic resistance and does not have a big effect on Isospora’s control.
A contaminated environment is the main source of infestation of piglets. Consequently, hygiene and management practices are the main factors to reduce infection pressure. Besides, cleaning and disinfection procedures of the farrowing room do not completely remove all the oocysts and the few remaining may be enough to transmit the parasite infestation.