In this article we will discuss about Rinderpest in Animals: 1. Definition of Rinderpest 2. Etiology of Rinderpest 3. Bacteriology 4. Resistance 5. Incidence 6. Mortality 7. Animals Susceptible 8. Modes of Infection 9. Incubation Period 10. Postmortem Lesions 11. Symptoms 12. Mouth Lesions 13. Cutaneous Lesions 14. Diagnosis 15. Course 16. Treatment 17. Immunization.
Definition of Rinderpest:
It is an acute febrile, infective disease of cattle and buffaloes and many other ruminants characterised by inflammatory and necrotic changes in the mucous membrane, specially of the alimentary tract and caused by a virus.
Etiology of Rinderpest:
The causative myxovirus are of many strains with considerable variation in virulence between them.
Bacteriology in Rinderpest:
The virus is present in the blood, tissue fluids and in all the secretions and excretions, as well as, evacuations but chiefly in the urine during the acute stage of the disease. In the blood, it is intraleucocytic and is absent from the serum. It retains its virulence by passage through cattle but is attenuated by passage through goats and sheep and—of recent practice— through embryonic chicken and rabbits.
The vaccine prepared by passage through rabbits is reported to be best and is known as Lapinized vaccine.
Attempts at culture and rendering the virus visible have so far failed.
Strains of virus of varied origin behave uniformly from the immuno-biological standpoint, that is why animals immunised with one strain are resistant to any other strains. Consequently, pleurality of virus is inadmissible (which is not the case with virus of foot and mouth disease). This virus seems to have some antigenic relationship to the viruses of Distemper and Measles.
Resistance to Rinderpest:
The virus is of a low resistance, so much so—that glycerine which is widely used in preserving viruses and vaccines—destroys Rinderpest virus.
Outside the living body, the virus does not survive more than 2 days even in protected places and sheds. Direct sunlight kills it in a few hours. It is also easily killed by heat and disinfectants. The virus is quickly destroyed by putrefaction, so in tropical countries like India, the carcasses of animals dead of Rinderpest are free from virus in a few hours due to putrefactive influences. In faeces and urine, the virus is killed in 36 hours.
Incidence of Rinderpest:
Rinderpest causes enormous loss amongst cattle in regions previously free from infection, but in permanently infected regions, it usually assumes a milder form with only a slight loss. That is why indigenous breeds of cattle in the plains of India where the disease is widely prevalent almost throughout the year, develop a strong power of resistance; whereas the animals in the hilly areas of India, where the movement of cattle is limited and their intermixing difficult, the cattle are highly susceptible. Similarly, the imported breeds are also highly susceptible.
Mortality in Rinderpest:
The mortality in case of cattle of the plains is very low (about 20 per cent); whereas in. case of cattle of hilly areas and imported breeds, it is often 90 per cent or more.
Animals Susceptible to Rinderpest:
Spontaneous infection occurs principally in cattle and buffaloes and occasionally amongst goats and sheep.
Zebu (East Indies cattle or Indonesian), yaks (Tibetan Cattle), Camels, Swine and all wild ruminants are susceptible in a more or less degree, but rodents, carnivora, birds and man are resistant.
Age has no influence on susceptibility except in the case of suckling calves, particularly of immuned mothers, who are often resistant to infection, but it is uncertain whether this is merely a lactation immunity or a hereditary specific immunity.
Recovery from Rinderpest usually confers immunity of a permanent nature, second attacks are exceptional and when these occur, are of a very mild form.
Calves in the wombs of infected mothers are infected and immunised during their intrauterine life.
Modes of Infection of Rinderpest:
Natural infection usually takes place by ingestion. Sometimes, the infection may take place through the nasal passages or through the conjunctiva, probably even when the mucosa is normal.
Incubation Period of Rinderpest:
3 to 9 days, in exceptional cases 10 to 17 days.
Postmortem Lesions of Rinderpest:
The carcasses are greatly emaciated. The areas round the sunken eyes, nose and mouth are covered with tenacious mucous or saliva and the anal region with faeces. The rectal mucosa if visible un open, is dark red and swollen.
The most important changes are found in the mucosa, especially of the digestive tract. (For the lesions in the oral cavity, please refer relative portion of symptoms).
The mucosa of the pharyngeal cavity may be reddened and covered either with slimy deposits or with dipitheretic membranes. There are haemorrhages and erosions on the mucosa of rumen and omasum. The mucosa of the abomasum (which usually contains a little tenacious mucus) and also that of the small intestine, are highly congested, swollen and the surface covered with haemorrhages, areas of erosions, necrosis and membranous deposits. The contents of the small intestines are fluid and dirty grey or dark brown from admixture with blood, often mixed .with membranous shreds and has a very foetid odour.
The large intestine show similar changes m a more or less degree. The rectum is invariably affected and shows parallel bands of congestion referred to as “Zebra markings”.
The gall bladder is often dilated and contains thin or yellow bile, occasionally reddish or mixed with blood. Is mucosa often shows numerous greenish grey crusts, slightly raised in the centre or it may contain rounded ulcers.
The lungs are congested and sometimes contain foci of catarrhal pneumonia and often interstitial emphysema (The pulmonary lesions are particularly common in goats). The lymphatic glands—specially of the mesentery—are acutely swollen.
Symptoms of Rinderpest:
The very first symptom is rise of temperature (104°F or 40°C to 108°F or 42°C) which with daily variation of about a- degree, usually reaches its highest point on the third or fourth day. In severe cases, the temperature rapidly falls below normal at the onset of diarrhoea; whereas, in favourable cases, it gradually comes down to normal with the onset of diarrhoea and practically remains constant. In lactating cows, diminution in milk secretion is observed during the fever.
From the second or third day of the febrile period, the animal manifests severe depression and stupor. The appetite is depressed, thirst increased, rumination retarded and finally suppressed. Defecation occurs at long intervals and the faeces are dry, dark coloured and coated with mucus. The urine is scanty and dark coloured. The respiration and pulse are accelerated and in the initial stage, cough is common in many animals without any physical sounds in the lungs.
From the second or third day of the manifestation of the disease, inflammatory or necrotic changes in the mucosa develop. The conjunctiva is bright red, the eyelids are swollen with profuse lachrymation, which later becomes mucoid or even purulent and dries into crust usually at the inner canthus.
There is a nasal discharge, which at first is transparent and mucoid, later muco-purulent and afterwards a brownish thick secretion sometimes mixed with blood which dries into crusts on the muzzle and around the nose. The nasal mucosa is reddened, studded with small haemorrhagic spots and later on covered with thick muco-purulent deposits.
Mouth Lesions of Rinderpest:
The changes in the buccal mucosa which are important in diagnosis, are manifested at first by increased secretion of saliva, which flows from the mouth often mixed with blood and sometimes with air bubble; it is not viscid and therefore, does not hang in long strings as in foot and mouth disease.
The mucosa, specially in the under surface of the tongue, on the gums around the incisors, angles of the mouth and inner surfaces of the lips and cheeks is first studded with haemorrhagic spots or may be diffusely reddened. Soon after, small nodular elevations appear on the surface, which become soft and grey or yellowish grey in colour giving the mucosa an appearance as if it is sprinkled with flour or bran.
This is followed by formation of large plaques, which coalesce with each other to form a uniform grey or yellowish-grey coating resembling soft cheese, which can be easily removed with finger exposing irregular shaped, ragged-edged erosions surrounded by necrosed epithelium.
Affection of the intestines is manifested in the first few days by constipation as has been mentioned already, later on by profuse diarrhoea which soils the anal region. The faeces are liquid, dirty grey or clay coloured or dark brown, sometimes mixed with blood, mucus, detached tissues and membranous shreds and are passed with severe tenesmus causing protrusion of the rectum which is swollen and dark red in colour. Excessive thirst is manifested at this stage.
In cows and heifers, the vaginal mucosa shows more or less similar lesions as seen in the buccal mucosa but with mucoid or muco-purulent discharge. Pregnant cows often abort at the height of the disease but sometimes not till after recovery.
During the development of the symptoms described above, the animal becomes greatly emaciated with eyes sunken deeply. They now grind their teeth, nod their heads or move from side to side. Pressure on the lumbar region causes a painful bending of the backs.
The completely exhausted animals die usually after a prolonged death agony.
Cutaneous Lesions of Rinderpest:
In a proportion of cases, on the second or third day after the onset of the disease, lenticular haemorrhages appear on the udder and scrotum. At a later stage (at the onset of diarrhoea), papules and then pustules — the size of a pea — develop on the unpigmented skin of the inner surface of the thigh, the perineum, around the nose and mouth, sometimes also on the neck, along the back and behind the shoulder. These pustules mat the hairs and form into crusts which fall off when the condition improves.’
Diagnosis of Rinderpest:
This is based on symptoms and the postmortem lesions. The dull aspect of the sunken eyes with purulent secretion, the dirty nasal discharge, the lesions in the mouth with dripping of saliva, the grinding of the teeth, the emaciated condition, the frequent liquid faecal evacuations and a foetid odour emitting from the whole body present a characteristic picture of the disease which is quite diagnostic.
Course of Rinderpest:
In typical cases, 4 to 8 days. In some cases, the condition is aggravated so rapidly that the disease may be fatal on the second or third day or in a fulminating case in a few hours. In other cases, the course may extend to 2 to 3 weeks when the animals become extremely emaciated and die of chronic gastro-intestinal catarrh.
Treatment of Rinderpest:
Medicinal treatment appears to have no definite influence on the course of the disease. However, in India, treatment is occasionally successful and this may be attributed to the disease being enzootic in nature and often appearing in mild form.
The constipation shown in the early stages may be relieved by small doses of saline, which, however, should be discontinued when diarrhoea sets in.
It has been found that Sulphaguanidine, Succinyl sulphathiazole and phthalyl sulphathiazole have some effect in helping a cure.
The main and most important point is to support the strength of the animal by good nursing and proper diet.
Results from serum treatment are doubtful when the disease is fully developed and completely negative when enteritis sets in. In the very early stages of the disease, serum treatment may be effective if given in large doses.
Immunization for Preventing Rinderpest:
This is done by subcutaneous injection of hyper-immuned serum to confer immediate protection in susceptible animals and thereby curtail the spread of infection.
Hill and other foreign breeds — 10ml per 50kg B. W/ minimum — 30ml.
Indian plain cattle and buffalo — 5ml per 50kg B. W. — minimum — 20ml.
It is advisable that after inoculation with serum, all the inoculated animals should be turned out together with the infected herd, so that, the inoculated animals may get an opportunity to contract a natural infection and thus acquire an active immunity.
The immunity conferred by serum is of short duration — about 10 days, so if the inoculated animals are subject to infection for a longer period, they should be re-inoculated.
The simultaneous serum-virus vaccine has been virtually discarded because of the danger of spreading the disease.
In India, Goat-tissue vaccine — 0.5 per cent emulsion of which made with normal saline given in 1ml doses produces life-long immunity.
Other very good vaccines:
Lapinized and chicken-embryo are also in use without any side effects.
Measles vaccine protects calves against Rinderpest at an age when ordinary Rinderpest vaccines are ineffective. It is also an efficient vaccine for use in adult catties.