List of four major protozoan diseases found in animals:- 1. Amoebiasis 2. Gardiasis 3. Anaplasmosis 4. Coccidiosis.
Contents
Protozoan Disease # 1. Amoebiasis:
Definition:
This is a disease common in man, has also been found in dogs. It is caused by Entamoeba histolytica, a protozoa of the order Amoebida and characterised by dysentery. Young cats are also susceptible to certain extent.
Symptoms:
The main symptom is dysentery, the faeces consisting mostly of blood and mucus and very little of faecal matter. The defecation is attended with marked straining, sometimes causes prolapse of the anus. There is pronounced weakness and the appetite may be impaired or unchanged.
In chronic cases, the animal develops anaemia and becomes greatly emaciated.
Postmortem lesions:
The mucosa of the large intestine, specially the caecum is thickened, congested, ulcerated and coated with thick-mucoid or muco-purulent exudate streaked with blood.
Treatment:
Absolute rest, liquid nutritious diet of a demulcent nature.
Metronidazole tablets or syrup given twice or thrice daily for 5 days will get: rid of the infection and may be continued for 10 days, if infection persists. There is also a single dose therapy — Secnidazole — the recent drug is very effective. Combined therapy with Sulpha drugs, such as, Sulphaguanidine, Phthalyl sulphathiazole along with Metronidazole may be used in the treatment of amoebic dysentery with good result.
Protozoan Disease # 2. Gardiasis:
Definition:
It has long been known that Giardia is present in the intestinal tract of dogs and other animals and man. Giardia canis is found in the dog whereas Giardia lamblia is found in man. There is no differentiating characteristics between Giardia canis and Giardia lamblia and quits often Giardia lamblia is transmitted to dogs. This is quite important from public health point of view since man and dog can infect each other.
Symptoms:
It depends on the general condition of the host. Diarrhoea starts about a week after ingestion of cysts. Cysts can be found in the faeces. As the infection becomes more acute, the faeces is mixed with mucus and blood.
Treatment:
Atabrine given in doses of 25 to 200 mg. twice daily for 2 to 3 days have proved quile effective in the treatment of giardiasis. Mepacrine, Chloroquin and other anti-malarial drugs may also be used with good results. Single dose therapy with the latest wonder drug — Secnidazole is also excellent.
Protozoan Disease # 3. Anaplasmosis:
Synonym:
Gall sickness.
Definition:
Anaplasmosis is a febrile disease of cattle, sheep and goats manifested chiefly by symptoms of anaemia and icterus and caused by a very small protozoal blood parasite of the genus Anaplasma (Suborder — Piroplasmidia) which consist entirely of coccus-like particles of chromatin.
Bacteriology:
Anaplasma marginal was first identified as an independent parasite by Theiler. Anaplasma are round or oval intercellular organisms having a diameter of 0.1 to 0.6µ. Within the body, they are only found in red blood corpuscles, as high as 50 per cent of which may be infected during the febrile stage. They may also be found in the blood of recovered animals.
Incidence:
The disease is very common in Africa but has since been seen in many other countries including Asia and Australia.
The Anaplasmata are commonly seen in association with infection by Babesia bigemina and Theileria mutans.
Animals susceptible:
Cattle, Zebu and buffaloes are naturally susceptible. Sheep and goats are susceptible to inoculation.
Modes of infection:
Transmitted by ticks, chiefly Boophilus Hyalomma, Rhipicephalus, Ixodes, Dermaceutor and Haemaphysalis. Infection is passed through the egg to the next generation of ticks. Several species of Tabanid flies have been shown to be mechanical carriers provided the transfer of infective material from an infected animal to a healthy animal is done within 5 minutes.
Incubation period:
6 weeks to 3 months after the bite of a lick and 14 to 40 days after inoculation.
Postmortem lesions:
Carcass extremely emaciated and icteric. Tissues anaemic, gelatinous oedema of the neck and shoulder, enlarged spleen and liver. Gallbladder is distended with thick greenish black bile. Serous cavities contain fluid. Icterus is general and marked throughout all organs of the body, including Central Nervous System. The kidneys are normal, and only slight changes are found in the digestive tract. In chronic case, the liver is about twice the normal size and badly degenerated, the blood is watery and bone marrow yellow. The lungs are anaemic or icteric.
Symptoms:
Peracute form is observed in milch cows. The onset is sudden with marked depression, high fever and complete suspension of milk flow. Saliva droops from the mouth, ears droop and the muzzle is dry. Death occurs in a few hours.
The acute type presents sudden high fever with great prostration and loss of appetite, laboured respiration, frequent pulse, constipation or diarrhoea, swelling of the eyelids with lacrimation, oedematous swelling in various parts of the body, specially neck and shoulder.
At a later stage, anaemia and icterus of the mucosa and unpigmented areas of the skin develop and the animal becomes rapidly emaciated. Mortality is high and death occurs within 2 to 3 days.
N. B.:
Haemoglobinuria rarely occurs.
The chronic form is usually a continuation of acute form in which RBCs drop from normal 7 millions per ml3 to 1 to 2 millions. The clinical symptoms manifested by low fever, anorexia, thirst, emaciation, high pulse and marked jaundice. 3 or 4 months are required for recovery. Extreme anaemia may lead to intense generalised icterus and death.
Young animals appear to be resistant and cases in calves under one year is rare. Calves suffering from mild form present rough coat, dullness, lack of appetite, slight constipation and loss of condition. Recovery occurs in a few days.
Mortality:
This may reach 80 per cent in a marginal infection.
Treatment:
Previously, the best treatment for clinical cases was Sodium Cacodylate. The dose was 1.6 gm to 2 gm per 40 kg body weight in 5% dextrose solution with 0.5 gm/ 30% solution of the drug per ml of the solution.
In recent years, treatment of Anaplasmosis is being done with broad spectrum antibiotic. In clinical cases, Tetracycline — 6-10 mg/kg body weight given in a single injection is effective, although it would be better to give three such daily injections.
Animals recovering from Anaplasmosis remain in a state of premunition and remain carriers for long periods.
Prophylaxis:
Injection of 5 ml of blood containing A. Centrale gives high degree of immunity against infection of A. marginal.
Oral administration of Chlortetracycline 10 mg/ kg body weight for (30-60 days) or 1 mg/kg body weight for 120 days are both effective in eliminating the carrier state. Immunity persists for 6 months, an important feature in herd management.
Protozoan Disease # 4. Coccidiosis
In Cattle:
Definition:
This is a disease chiefly of young animals between the age of 4 months to 2 years caused by the invasion of the large intestine, specially caecum with Eimeria zurnii — a protozoan of the order Coccidia and characterised by watery faeces mixed with mucas and blood.
Modes of infection:
By ingestion of fodder and water, contaminated with faeces containing the oocysts.
Incubation period:
1 to 3 weeks.
Postmortem lesions:
Mucosa of the large intestine, specially the rectum is congested, thickened, corrugated and coated with greyish or brownish gelatinous exudates. The surface is eroded and studded with haemorrhagic spots. In severe cases, there may be necrosis of large intestine. Haemorrhages in pericardium and pleura are also seen.
Symptoms:
The affected animal stands with arched back and head forward, loss of appetite. Pulse is fast — 80 to 120; mucosa pale, blood examination reveals extreme anaemia. Pneumonia is frequent in calves. Passage of foetid watery faeces with mucus and blood, attended with severe straining, which sometimes causes prolapse of the rectum. Progressive anaemia and emaciation. In some cases, there may be rise of temperature which is variable. Death may occur within a week or 10 days with mortality from 5 to 15 per cent.
Old animals, when infected, seldom manifest any definite symptom but remain as carriers and act as a source of infection to susceptible young animals.
N. B.:
The disease may appear enzootically by drinking in one pool.
Diagnosis:
Detection of the oocysts in the faeces by microscope by direct smear or better after floatation method.
Treatment:
All sick animals should be isolated. Demulcents and intestinal sedatives may be given. Sulphamezathine or Sulphaquinoxaline in daily doses 140 mg/kg B.W. for 3 days gives satisfactory results if given early. Nitrofurazone 150 mg/kg B.W. is also another good drug. Combined therapy with Chlortetracycline and Sulphadimidine may be used for prophylaxis.
In Sheep and Goat:
Definition and Causal agents:
At least seven species of Eimeria in these animals, mixed infections with two or more species is the rule rather than the exception. The various species are widely distributed and, as a rule, the clinical disease is seen in lambs and kids, seldom in the old animals but they remain as carriers.
Symptoms:
Severe diarrhoea and emaciation and pernicious anaemia. There is no rise of temperature. The lesions are mostly in small intestine. The disease is a very serious one and the course may be very quick or may linger for several Weeks.
Treatment:
It is on the same lines as for cattle.
In Fowls:
Definition:
Nearly half a dozen species of coccidia are known to produce this disease in birds — of these two species — viz. Eimeria tenella and Eimeria nicatrix, are common and highly pathogenic and destructive. E. tenella causes caecal (haemorrhagic) coccidiosis, usually in young chicks and occasionally in adult birds.
E. nicatrix causes duodenal (chronic) coccidiosis in fowls approaching maturity and occasionally in young chicks. E. maxima and E. hagani causes chronic coccidiosis being of low virulence. E. hagani is not wide spread. Several species occur simultaneously in a single bird and this condition occurs mostly in older birds. Birds recovering from acute attack, completely become free from all traces of infection provided there is no reinfection. Chronic coccidiosis occurs chiefly due to repeated reinfections with the same or other species.
Mode of infection:
Ingestion of contaminated food and water.
Birds susceptible:
Practically all birds.
Symptoms:
In acute form, severe and obstinate diarrhoea, excessive thirst and prostration. No change in appetite in the beginning, later inappetance takes place, salivation starts and stupor commences. The faeces (droppings) are yellowish brown with mucus and blood which are passed with much straining. After the bird becomes extremely emaciated and paralysis sets in, it dies in 2 to 4 days. The bird may die also without any previous symptom.
In subacute form, which is common in adult birds, the disease develops slowly and runs a course of 2 to 4 weeks. The prominent symptoms are drooping of the wing and excessive lengthiness of the face with severe weakness. Diarrhoea is not always a common symptom in adults.
One attack with E. tenella is supposed to confer immunity against subsequent attacks but the bird remains a carrier.
Postmortem lesions:
The lesions may occur throughout the intestine, the commonest sites being the caeca in chicks and duodenum in the older birds and vary with the intensity of the infection. In the caeca, there are cheesy masses adherent to the wall, which, when removed, leave a roughened and haemorrhagic surface — or else the caecal wall may be highly inflamed and the contents blood-stained.
In the small intestine, more specially in the duodenum, there is varying degree of enteritis with chronic thickening of the wall. Grey spots or haemorrhages through the serous coat and indicate deep seated colonies of the parasites. The mucosa is coated with dirty slimy exudate, on washing of which, ulcers are sometimes found.
Coccidia can be easily detected in the caecal contents, but, in the small intestine, deep scrapings of the inner coats are often required to demonstrate them, which must be borne in mind in the diagnosis of duodenal coccidiosis in adults.
Treatment:
The administration of various ‘Sulpha’ drugs will either kill the coccidia or arrest their development.
Sulphathiazole and Phthalyl sulphathiazole are good drugs. Sulphadiazine are most effective, Sohithiazole (20%) 50 ml to a 5 litres of water should be the only source of drinking water for 3 to 4 days or longer but never more than 7 days.
Sulphamezathine:
1% in mash fed for 3 days after the 4th day of infection is very effective, but if the treatment is started on the 5th day of infection it produces heavy mortality.
Sodium sulphamerazine administered in drinking water is superior to relatively insoluble Sulphamezathine (1%) both as a preventive and curative in Coccidiosis.
Sulphaquinoxaline and Nitrofurazone are of value. These drugs are given in food or water. But care must be taken if given in wrong doses—it may produce symptoms of poisoning.
Sulphamerazine:
2 gms per 500 gms of mash fed for 3 days checks the disease. The same at the rate of 1 gm per 500 gms for 6 days protects the chicks.
It is reported that Chlorodiazine and Bromodiazine are 10 times as effective in the control of coccidiosis in poultry as Sulphaguanidine.
Control of the disease:
After their elimination in the faeces, the oocysts of the Eimeria take 21 to 48 hours to become mature and infective, therefore, to control an outbreak, the life cycle of the organism should be interrupted at this stage.
With the first appearance of droopiness and lack of appetite in the growing stock, specially in the absence of any respiratory symptom, coccidiosis must be suspected and the entire flock should be shut up in places from which droppings could be removed every 24 hours for at least a week. A dose of Epsom salt at this stage, better in drinking water or wet mash, helps to purge out many harmful forms of coccidia.
During this period, milk in some form (preferably Iodised milk) should be given to maintain the vitality and whole grain withheld from the diet. At the end of the period of confinement, the flock should, if possible, be placed in a new range with an access to liberal quantities of fresh green feed.
Birds in acute condition should at once be removed from the flock and destroyed. Adult birds, due to constant reinfection in nature, become reservoirs of infection for the growing stock. It is, therefore, advisable not to allow young stocks to mix with the adults.
Avoid transfer of infection by the attendants or visitors. Attendants who handle the adult birds should not come in contact with the young stock, and, where this is not possible, the attendant should free himself of the possible infection by changing his apparel and wash his hands thoroughly with disinfectants and using surgical gloves before attending the young stock.
The oocysts of coccidia cannot stand heat and drying, therefore, the best way to deal with them is to expose the droppings and litter to natural forces of drying and, at the same time washing of the utensils, pens and cages with boiling water.
In poultry farms, where poultry houses are with mud floors, it is convenient to have several such enclosures, so that these can be used in rotation one after the other after they have dried completely. In pens with pucca floors, an extra pen is useful, for while one is in use, the other one can be made ready for the next day by thorough washing with boiling water.
No measure will be of any use in controlling coccidiosis unless careful attention is given to sanitation.