Veterinary Virology: Parvovirus and Leptospirosis

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Questions and Answers

What is the most definitive test for diagnosing the cause of mummified piglets?

Fluorescent antibody testing of frozen lung smears (correct)

Serological testing

Clinical signs assessment

Vaccination history review

How often should sows be vaccinated assuming they wean their piglets?

Every 2 months

Every 6 months (correct)

Every month

Annually

Which serotype is most commonly associated with reproductive failure in cases of leptospirosis?

L.borvettii

L.bratislava

L.pomona (correct)

L.interrogans

What method for vaccination was used prior to the availability of commercial vaccines?

Feeding frozen parvo-infected material to gilts Signup and view all the answers

What is a common reservoir for Leptospira on farms?

Open water sources exposed to wildlife Signup and view all the answers

What is the primary route of infection for Leptospira spp.?

Ingestion and direct contact Signup and view all the answers

How long after infection can Leptospira be shed in urine?

For months after clinical recovery Signup and view all the answers

What clinical issue can occur due to infection with L.pomona?

Serious abortion problems Signup and view all the answers

What are common clinical signs of seasonal infertility in sows?

Increased number of NIP sows at farrowing Signup and view all the answers

Which environmental factor is believed to contribute to seasonal infertility in swine?

Restricted feeding Signup and view all the answers

At what times of the year does seasonal infertility most commonly occur in pigs?

July, August, September Signup and view all the answers

What effect does photoperiod have on sows concerning seasonal infertility?

It may stimulate seasonal infertility due to changes in light length Signup and view all the answers

What is a proposed solution to mitigate seasonal infertility in swine?

Implement controlled photoperiods within housing Signup and view all the answers

Why does the incidence of autumn abortion increase in certain climates?

Substantial temperature drops in barns from day to night Signup and view all the answers

What aspect of sow physiology changes in the autumn that may affect pregnancy?

Lower levels of progesterone than in other seasons Signup and view all the answers

What management practice can help reduce the incidence of seasonal infertility?

Increasing sow feed intake in the initial weeks post-breeding Signup and view all the answers

What is one method to minimize autumn abortion in swine?

Increasing ambient temperatures in gestation barns Signup and view all the answers

Which disease is primarily associated with swine but can occasionally infect humans?

Swine vesicular disease Signup and view all the answers

What is a primary clinical feature of systemic viral diseases in swine?

Anorexia and lethargy Signup and view all the answers

Which of the following statements about hog cholera is correct?

It is reportable in Canada and the United States. Signup and view all the answers

What is a known consequence of systemic viral diseases like African swine fever?

Vasculitis leading to hemorrhage and edema Signup and view all the answers

Which of the following diseases is historically linked to a widespread epidemic due to feeding uncooked fish waste?

Vesicular exanthema Signup and view all the answers

What are the common gross lesions identified in hog cholera?

Petechial hemorrhages and splenic infarcts Signup and view all the answers

What temperature indicates a high fever in pigs, which is a common symptom of systemic viral diseases?

41°C Signup and view all the answers

What clinical sign is typically associated with subclinical leptospirosis infection in pigs?

High prevalence of white-spotted kidney lesions Signup and view all the answers

Which reproductive disorder is most commonly linked to L.bratislava infection in sows?

Mummified fetuses Signup and view all the answers

What is the primary route of transmission for leptospirosis in pigs?

Urine of carrier animals Signup and view all the answers

What postmortem finding is indicative of leptospirosis in affected pigs?

Kidney lesions Signup and view all the answers

Which treatment option is recommended to eliminate renal carriers of leptospirosis?

Parenteral treatment with streptomycin Signup and view all the answers

What is the purpose of using killed bacterins in sows?

To vaccinate against L.pomona and L.bratislava Signup and view all the answers

Which of the following is a common misconception about vaccination for leptospirosis?

It protects against renal colonization and shedding Signup and view all the answers

What is a primary characteristic that differentiates African Swine Fever from Hog Cholera?

Mortality rates approaching 100% Signup and view all the answers

What complicates the identification of clinical signs of leptospirosis in piglets?

Signs are often very subtle and non-specific Signup and view all the answers

Which species is primarily affected by Japanese B. Encephalitis as a reservoir?

Pigs Signup and view all the answers

Which of the following diseases is characterized by encephalomyelitis in young pigs?

Blue Eye Disease Signup and view all the answers

What is a common clinical symptom of pharyngeal anthrax in swine?

Marked cervical swelling Signup and view all the answers

Which disease is specifically diagnosed only in swine and has not been reported outside Mexico?

Blue Eye Disease Signup and view all the answers

Which virus is associated with historically attributed infertility and stillbirths in swine that later included enteroviruses?

Enteroviruses Signup and view all the answers

What type of disease does Teschen Disease cause in affected swine?

Polioencephalomyelitis Signup and view all the answers

How can swine contract Brucellosis most commonly?

Ingestion of contaminated feed Signup and view all the answers

Study Notes

Parvovirus

Most definitive test for diagnosis is fluorescent antibody testing of frozen lung smears from mummified piglets
Serology shows the presence of antibodies to parvovirus but is not valuable in diagnosing the cause of an outbreak.
Commercial vaccines are available
Producers are encouraged to use killed vaccines
Gilts are vaccinated one month and two weeks prior to breeding
Sows are vaccinated when they wean their piglets (about every 6 months)
Sow vaccination may not be necessary but is usually performed due to combination with other vaccines
Traditionally, producers would grind up mummies from parvo-infected litters and freeze this solution which was used as a live autogenous oral vaccine.

Leptospirosis

Outbreaks of leptospirosis abortion are uncommon and unpredictable.
L.pomona is the serotype most commonly associated with reproductive failure.
L.bratislava has been shown to be present in a large number of herds and has occasionally caused serious abortion problems and infertility due to fallopian tube infections.
Leptospira spp. are sensitive to most soaps, disinfectants, and are rapidly destroyed by drying but may persist for months in water.
Open water sources exposed to wildlife can be reservoirs for Leptospira.
Infection occurs by ingestion, direct contact, and entry through abrasions, transplacental transmission, or by the venereal route.
The organisms multiply to produce septicemia which may cause clinical signs.
In L.pomona infections, organisms penetrate from the blood vessels through the interstitial tissue of the kidney to the basement membrane within 3 – 5 days of infection
Leptospira are shed in the urine from time-to-time for months after clinical recovery.
Localization in the pregnant uterus can cause fetal invasion and abortion 10 days to 4 weeks after infection.

Leptospirosis - Clinical Signs

Most infected pigs do not show clinical illness.
Leptospirosis has been diagnosed in finishing barns because pigs at market show a high prevalence of white-spotted kidney lesions.
In rare circumstances, piglets can become infected and may show signs of dullness, anorexia, and diarrhea.
Neurological signs can occur.
Clinical signs of reproductive disorders include abortion, stillbirth, and neonatal mortality, sometimes accompanied by fever, and anorexia in the sow.
Jaundice is occasionally seen.
Abortion occurs late in gestation, often within one or two weeks of term.
Mummified and macerated fetuses also occur commonly amongst litters of sows with leptospirosis.
L.bratislava is believed to be responsible for cases of infertility characterized by repeat breeding.
This organism localizes in the fallopian tubes and uterus.

### Leptospirosis - Epidemiology

The disease is most commonly spread through the urine of carrier animals.
Venereal transmission of L.bratislava is important.
Wild animals can be important sources of infection, particularly rodents.
Leptospirosis has been associated with providing sows with water from a pond or other open water source.
Human infection from infected pigs is a concern as it is a zoonotic disease.

Leptospirosis - Diagnosis

Late-stage abortion, birth of weak piglets, fever, and icterus in older piglets are characteristic of leptospirosis.
Postmortem findings of kidney lesions may suggest leptospirosis.
Diagnosis can be confirmed by demonstrating a rising titre of antibody to the appropriate strain.

Leptospirosis - Treatment

Abortions may be prevented and renal carriers eliminated by parenteral treatment with streptomycin (25 mg/kg) as a single injection.
Feed medication with tetracyclines at a level of between 400 and 800 gm per tonne has been recommended as well.

Leptospirosis - Control

Killed bacterins containing 7 serotypes including L.pomona and L.bratislava are commercially available and used on almost all sows in Ontario twice before breeding gilts and at each weaning.
These are usually combined with porcine parvovirus (PPV).
Vaccination may not prevent renal colonization and shedding of the organism during a herd outbreak, therefore herd medication is required.
Eradication of the disease involves a thorough clean up of the environment, rodent elimination, and herd medication.
Leptospira can survive freezing.
Feedback programs for parvovirus control could predispose to leptospiral infection.

Seasonal Infertility

Herds experience lower reproductive performance in July, August, and September.
This problem occurs on approximately 10% of farms, and its effects can vary from year to year.
Where pigs are raised outdoors or in open-sided barns, the incidence tends to be much higher.

Seasonal Infertility - Clinical Signs

An increased number of sows returning to heat at irregular times (> 25 days) and/or an increase in not-in-pig (NIP) sows at farrowing are characteristic of this syndrome.
A NIP sow is one which is found open in the farrowing crate.
Regular 21 day returns are generally constant throughout the year.
Delayed puberty often occurs along with the decreased farrowing rate.
The weaning-to-breeding interval tends to be longer during the July-August-September period as well.

Seasonal Infertility - Pathogenesis

European wild boars are seasonal breeders
It is thought that there is still a tendency in domestic swine to prefer not to farrow at the beginning of winter.
Weaned sows and gilts are less likely to begin to cycle in August.
Sows, which have been bred are apt to lose their pregnancy more easily in the fall than at any other time of the year.
Photoperiod is thought to be of importance in stimulating seasonal infertility to occur but the exact mechanism is unknown.
Restricted feeding and heat stress appear to be factors.
Melatonin is highest in sows in the late summer.
Levels of progesterone in pregnant sows in autumn are lower than at other times.

Seasonal Infertility - Treatment and Control

Confinement housing, controlled photoperiod, and individual stalls tend to reduce the risk of seasonal infertility.
If pens are used, sows should be housed according to parity to separate young parity sows from older parity sows.
Increased sow feed intake for the first 3 weeks after breeding will reduce the problem of seasonal infertility.
Anticipate from previous experience and breed more gilts.

Autumn Abortion Syndrome

In cold climates, there is a higher incidence of abortion in October and November than at other times of the year.
This occurs with stalled sows in barns where the barn temperature drops substantially from day to night.
Autumn abortion can be minimized by increasing feed intake and/or increasing ambient temperatures in gestation barns.

Swine Vesicular Diseases

Swine Vesicular Disease (Picornaviridae)

Affects primarily swine, but humans have occasionally been infected.
It is very difficult to eradicate from the environment.
First diagnosed in Italy, later other European countries but has not occurred in North America.

Vesicular Stomatitis (Rhabdoviridae)

Seldom causes disease in pigs, more commonly a cattle problem.
Vesicular stomatitis can affect horses, wildlife, and humans.
It is endemic in certain areas of southeast USA, but not in Canada.

Vesicular Exanthema or San Miguel Sea Lion Disease (Caliciviridae)

Still exists in marine life along the California coast, but has not been diagnosed in pigs since 1956.
A widespread epidemic occurred in the USA from feeding uncooked fish waste to pigs.

Systemic Viral Diseases (FAD)

These diseases are characterized by high fever (> 41°C), anorexia, and lethargy.
Systemic diseases are usually associated with one predominant sign (central nervous system {CNS} signs, lameness, etc.).
Some systemic diseases affect a wide variety of body systems and do not present a clear-cut predominant sign.
These diseases tend to be severe and include diseases such as hog cholera (HC), African swine fever (ASF), and salmonellosis.
Clinical presentation of these three diseases can be similar and differential diagnosis may be difficult.
These diseases cause vasculitis, resulting in hemorrhage and edema. Postmortem lesions include petechiae and ecchymosis on skin, kidney, and lymph nodes. There may be splenomegaly and infarction. Hemorrhage may occur in the brain and CNS signs might be observed.
ASF or HC are reportable diseases in Canada and the United States and federal veterinarians must be notified immediately.

Hog Cholera or Swine Fever (Pestivirus, Togaviridae)

Canada and the United States are free of this important pathogen.
The clinical signs include depression with drooping head, fever (> 41°C), huddling, diarrhea or constipation, and nervous signs.
Mortality can be very high.
Gross lesions include petechial hemorrhages throughout the body including kidney (turkey-egg kidney) and often, splenic infarcts.
Clinical signs are similar to Salmonella cholerasuis.

African Swine Fever (Iridoviridae)

This disease is difficult to distinguish from Hog Cholera based on clinical signs and gross lesions.
Mortality generally was higher than for HC, approaching 100% but milder forms have evolved.
African Swine Fever has spread via food wastes, from ships and air travel to the Caribbean, Brazil, and Europe.
Clinical symptoms are similar to Salmonella cholerasuis.

Japanese B.Encephalitis (Flavivirus)

This disease is spread by mosquitoes, can cause disease in other domestic animals as well as some birds, reptiles, and humans.
Pigs are a reservoir for the disease.
Geographically, the disease is restricted to eastern Asia including Japan, Korea, India, and Nepal.
In swine, the clinical signs are restricted to the fetus and occasionally suckling pigs.
Stillbirths, weak newborns, and CNS disease of piglets is typical.

Blue Eye Disease (Paramyxovirus)

This disease has only been diagnosed in swine and has only been observed in Mexico.
Clinical signs include encephalomyelitis in young and growing pigs (ataxia, muscle tremors, paddling, blindness).
Corneal opacity occurs in 1 - 10% of piglets.

Teschen and Talfan Disease (Enteroviruses)

Teschen is a severe disease causing high mortality occurring in Central Europe and parts of Africa.
Clinical signs are due to a polioencephaloymelitis.
Talfan is a milder disease that has occurred infrequently in North America.
Enteroviruses are widespread, but generally not associated with disease problems in Canada.
At one time stillbirth, mummification, embryonic death & infertility (SMEDI) syndrome was attributed to these viruses.
In an outbreak of mummies and infertility that is not caused by parvovirus, one should consider enteroviruses as a possible cause when investigating.

Reportable Bacterial Diseases

Anthrax (Bacillus anthracis)

Anthrax occurs when grazing animals ingest spores from contaminated pastures, but more likely in swine, infection results from ingestion of contaminated feed containing animal components such as bone meal.
Clinical signs may be absent – sudden death (systemic anthrax).
Swine with pharyngeal anthrax, the most common form show marked cervical swelling and marked dyspnea leading to suffocation.
Intestinal form of anthrax causes bloody feces.

Brucellosis (Brucella suis)

Canada is free of B.suis and the incidence in the USA is quite low.
B.suis can infect humans and cattle.
It can be transmitted via semen, but more commonly from ingestion of infected fetuses.

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This quiz covers the essential aspects of parvovirus and leptospirosis in veterinary medicine. Key topics include diagnosis methods, vaccination strategies, and outbreak management related to these diseases in livestock. Test your knowledge on the important serotypes and their impact on reproductive health.