Occurrence of Natural Infection with Mycoplasma Hyopneumoniae and Porcine Reproductive Respiratory Syndrome Virus (PRRSV) in Pigs Under German Field Conditions

ABSTRACT This article describes the first successful detection of airborneMycoplasma hyopneumoniae under experimental and field conditions with a new nested PCR assay. Air was sampled with polyethersulfone membranes (pore size, 0.2 μm) mounted in filter holders. Filters were processed by dissolution and direct extraction of DNA for PCR analysis. For the PCR, two nested pairs of oligonucleotide primers were designed by using an M. hyopneumoniae-specific DNA sequence of a repeated gene segment. A nested PCR assay was developed and used to analyze samples collected in eight pig houses where respiratory problems had been common. Air was also sampled from a mycoplasma-free herd. The nested PCR was highly specific and 104 times as sensitive as a one-step PCR. Under field conditions, the sampling system was able to detect airborne M. hyopneumoniae on 80% of farms where acute respiratory disease was present. No airborne M. hyopneumoniae was detected on infected farms without acute cases. The chance of successful detection was increased if air was sampled at several locations within a room and at a lower air humidity.

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Aerosol Detection and Transmission of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV): What Is the Evidence, and What Are the Knowledge Gaps?

Viruses ◽

10.3390/v11080712 ◽

2019 ◽

Vol 11 (8) ◽

pp. 712 ◽

Cited By ~ 10

Author(s):

Andréia Gonçalves Arruda ◽

Steve Tousignant ◽

Juan Sanhueza ◽

Carles Vilalta ◽

Zvonimir Poljak ◽

...

Keyword(s):

Current Knowledge ◽

Field Conditions ◽

Respiratory Syndrome Virus ◽

Transmission Route ◽

Knowledge Gaps ◽

Airborne Transmission ◽

Infectious Individual ◽

Transmission Data ◽

Outbreak Investigations ◽

Shed Light

In human and veterinary medicine, there have been multiple reports of pathogens being airborne under experimental and field conditions, highlighting the importance of this transmission route. These studies shed light on different aspects related to airborne transmission such as the capability of pathogens becoming airborne, the ability of pathogens to remain infectious while airborne, the role played by environmental conditions in pathogen dissemination, and pathogen strain as an interfering factor in airborne transmission. Data showing that airborne pathogens originating from an infectious individual or population can infect susceptible hosts are scarce, especially under field conditions. Furthermore, even though disease outbreak investigations have generated important information identifying potential ports of entry of pathogens into populations, these investigations do not necessarily yield clear answers on mechanisms by which pathogens have been introduced into populations. In swine, the aerosol transmission route gained popularity during the late 1990’s as suspicions of airborne transmission of porcine reproductive and respiratory syndrome virus (PRRSV) were growing. Several studies were conducted within the last 15 years contributing to the understanding of this transmission route; however, questions still remain. This paper reviews the current knowledge and identifies knowledge gaps related to PRRSV airborne transmission.

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Evaluation of the clinical efficacy of a water soluble formulation of tylvalosin in the control of enzootic pneumonia associated with Mycoplasma hyopneumoniae and Pasteurella multocida in pigs

Porcine Health Management ◽

10.1186/s40813-020-00177-9 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Alfonso Lopez Rodriguez ◽

Anna Catharina Berge ◽

Cliff Ramage ◽

Ryan Saltzman ◽

Rickie J. Domangue ◽

...

Keyword(s):

Drinking Water ◽

Pasteurella Multocida ◽

Natural Infection ◽

Mycoplasma Hyopneumoniae ◽

Lung Lesion ◽

Water Soluble ◽

Enzootic Pneumonia ◽

Challenge Study ◽

Lower Lung ◽

Clinical Cases

Abstract Background The efficacy of a water soluble formulation of tylvalosin (Aivlosin® 625 mg/g granules) was evaluated in the treatment and metaphylaxis of Enzootic Pneumonia (EP) in pigs. In all four trials, pigs in the tylvalosin group were administered 10 mg tylvalosin/kg bodyweight in drinking water daily for 5 consecutive days (TVN). In a single-challenge study, pigs were inoculated with lung homogenate containing Mycoplasma hyopneumoniae. In a dual challenge study, pigs were sequentially inoculated with pure culture of M. hyopneumoniae and Pasteurella multocida. Efficacy was evaluated based on reduction of lung lesions compared to unmedicated control pigs (CTL). In two field studies at European commercial farms with confirmed outbreaks of EP, treatment efficacy in clinically affected fatteners was evaluated based on improved clinical conditions compared to pigs treated with tylosin at 10 mg/kg by injection for 3 consecutive days (TYL). In these field trials, healthy in contact pigs were enrolled for metaphylaxis efficacy evaluation based on reduction in incidence of new clinical cases of respiratory disease compared to unmedicated pigs (CTL). Results In the M. hyopneumoniae-only challenge study, pigs in TVN group had lower lung lesion scores than CTL (6.52 vs. 14.97; p < 0.001). In the dual challenge study with M. hyopneumoniae and P. multocida, pigs in TVN group had lower lung lesion scores than CTL (3.32 vs. 8.37; p < 0.01) and the recovery of both challenge bacteria from the lungs was lower in TVN compared with CTL group (p < 0.01). In field outbreaks of EP, multicentre analysis showed that 13 days after the start of medication, treatment success for TVN pigs was significantly better than for TYL pigs (80.0% vs 48.7% p = 0.03) and metaphylactic administration of TVN significantly reduced the incidence of new clinical cases (2.1% vs. 7.8%; p < 0.01) compared with unmedicated controls. Conclusions Tylvalosin at 10 mg/kg daily for 5 days in drinking water was safe and effective in the treatment and metaphylaxis of EP in pigs associated with infections of M. hyopneumoniae either alone or in combination with P. multocida under both experimental challenge and field natural infection conditions.

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