Neonatal Streptococcal Infection

Streptococcal infection of the newborn is characterized by involvement of the navel and the subsequent development of bacteremia resulting in localization of the infection in other organs, particularly the joints. A binocular compound microscope can help in diagnosing these infections.

Streptococcus genitalium is usually recovered from the joints of infected foals and may also be present in the uterus of the mare and in aborted fetuses when tissue samples are examine under a binocular compound microscope. Other streptococcus that are isolated from clinically affected piglets and their normal littermates using a binocular compound microscope are Streptococcus suis although Streptococcus equisimilis is also capable of causing a similar disease in the same species. Group C streptococci and streptococcus fecalis (this can be observed with a binocular compound microscope) have been isolated from cases of polyarthritis and endocarditis in lambs and Streptococcus pyogenes from swollen joints in calves. The sporadic occurrence of the disease in some litters of pigs suggests that an increased susceptibility of the piglet could affect the epidemiological pattern of the disease. The common occurrence after tail docking and tooth clipping suggests that they may precipitate attacks.

Epidemiology
The source of the infection is usually the environment that may be contaminated by uterine discharges from infected dams or by discharges from lesions of infected animals. The microscopic pathogenic microorganism can be isolated from the nasopharynx of the sow, and direct infection from the sow to the piglet is suggested by some epidemiological data. The portal of infection in most instances appears to be the umbilicus, and continued patency of the urachus is thought to be a contributing factor in that it delays healing of the navel. Contamination of the umbilicus may result from infected soil or bedding.

Streptococci are the most common cause of post-natal infections of foals, representing 50% in such cases according to surveys. Up to 20% of abortions in mares are found to be due to streptococci in similar surveys. Affected foals may die or become worthless because of permanent injury to joints.

In pigs, lambs and calves, the disease is sporadic but a high incidence may occur on individual farms. In an extensive survey streptococcal arthritis was recorded in 18% of litters and the average morbidity 3.3% and the mortality 1.5%.

Pathogenesis
The infection spreads from the portal of entry to produce a bacteremia, which is not clinically detectable but could be diagnosed using bacterial culture examination using binocular compound microscopes. The period of bacteremia is variable but may last for several days in piglets. A terminal acute fetal septicemia is the common outcome in animals under 1 week of age but in older animals suppurative localization in various organs is more common. Arthritis is the most common manifestation but other complications may be encountered.

Clinical Findings Horses
Foals do not usually grow signs until 2 to 3 weeks of age. The initial sign is usually a tender swelling of the navel and surrounding abdominal wall, often in the form of a flat plaque that may be 15 to 20 cm in diameter. A discharge of pus may or may not be present and a patent urachus is a frequent accompaniment. A systemic reaction occurs but this is often mild. Lameness becomes apparent and is accompanied by obvious swelling and tenderness in one or more joints. The hock, stifle and knee joints are involved and there is an occasional extension to the tendon sheaths. Lameness may be so severe that the foal lies down most of the time, suck rarely and becomes extremely emaciated.

If the veterinarian has begun treatment in early stages, recovery occurs but when joint involvement is severe, particularly if the abscesses have ruptured, the animal may have to be destroyed because of the resulting ankylosis. Death from septicemia may occur in the early stages of the disease.

Pigs
Arthritis and meningitis may occur alone or together and are the most common in the 2 to 6 week age group. More commonly several piglets within a litter are affected. The arthritis is identical with that described in foals above. With meningitis there is a systemic reaction comprising of fever, loss of appetite and depression. The gait is stiff, the piglets standing on their toes and there is swaying of the hindquarters. The ears are often retracted behind the head. Blindness and gross muscular tremor followed by inability to maintain balance, lateral recumbency and violent paddling. With endocarditis the veterinarians often found young pigs comatose or dead without premonitory signs observed.

Sheep
The incubation period is short, usually 2 to 3 days, and outbreaks occur soon after birth or docking. There is intense lameness with swelling of one or more joints appearing in a day or two. Pus accumulates and the joint capsule often ruptures. Recovery usually occurs with little residual enlargement of the joints although there may be occasional deaths due to toxemia. Calves show polyarthritis, meningitis and ophthalmitis. The ophthalmitis may appear soon after birth. The arthritis is often chronic and causes little systemic illness. Calves with meningitis show hyperesthesia, rigidity and fever.

Tissue samples should be sent for bacterial culture examination using binocular compound microsopes in cases where these types of animal infections are suspected in order for early identification, treatment and control of the disease. Read more on this subject