Babesiosis
It is also known as red water disease or cattle tick fever and is characterized by fever, intravascular haemolysis, acute anaemia and haemoglobinuria.
Etiology: The disease is caused by Babesia species which is an intraerythrocytic parasite, and is mostly seen in rainy season when tick population is high. It occurs in pure exotic and crossbred cows in India while indigenous breeds are quite resistant to the infection. Animals below 1 year of age are more susceptible while infection in animals above 5 years of age is rarely seen.
Pathogenesis: After gaining entry into the circulation, the organisms multiply in peripheral or visceral vessels and there is haemolysis that results in anaemia, jaundice and haemoglobinuria. The death of infected animals occurs as a result of anaemic anoxia.
Clinical signs: In cows, sheep and goat, initially there is high rise of body temperature, anorexia, weakness, fall in milk yield and absence of rumination. Later on, they develop haemoglobinuria, anaemia and jaundice. Their heart and respiration rates are elevated. If affected animals are not treated, they die. Abortions are also noticed in pregnant animals. In horses, initially fever and anorexia occur later on the fever becomes intermittent. There is edema and animals are reluctant to move. Haemoglobinuria is usually not seen in equines but mucus membranes are anaemic and there is jaundice.
On postmortem examination, jaundice, soft enlarged spleen and enlarged dark brown coloured liver and enlarged kidneys are noticed. There is severe intravascular clotting.
Diagnosis: It is diagnosed by clinical signs and confirmed by examination of blood smear, serological tests like card agglutination and slide agglutination, ELISA, indirect fluorescent antibody and passive haemagglutination tests, and postmortem examination. Blood examination also reveals low haemoglobin and erythrocyte count and severe anaemia.
The disease should be differentiated from theileriosis, which has enlarged regional lymphnodes, leptospirosis which has severe toxaemia and blood mixed milk, nutritional haemoglobinuria which occurs immediately before or after parturition and reveals normal to subnormal temperature, haemoglobinuria, loud heart sounds and tachycardia and bacillary haemoglobinuria, which shows toxaemia, abdominal pain and diarrhoea/ dysentry.
Treatment: The animals can be treated well with diminazene aceturate @ 0.8- 1.6 g/100 kg body weight by deep intramuscular route. A total dose of 6 g can be given in adult animals and should be repeated after 3 days. Imidocarb is also highly effective when given @ 1 mg/kg body weight subcutaneously. At double dose rate, it completely eliminates the parasites from host. Occurrence of the disease can be reduced by controlling the tick population.