Babesiosis Lecture Notes PDF

Babesiosis Dr Jawad Younas Babesiosis is caused by intraerythrocytic protozoan parasites of the genus Babesia. Transmitted by ticks, babesiosis affects a wide range of domestic and wild animals and occasionally people. Although the major economic impact of babesiosis is on the catt...

Babesiosis Dr Jawad Younas Babesiosis is caused by intraerythrocytic protozoan parasites of the genus Babesia. Transmitted by ticks, babesiosis affects a wide range of domestic and wild animals and occasionally people. Although the major economic impact of babesiosis is on the cattle industry, infections in other domestic animals, including horses, sheep, goats, pigs, and dogs, assume varying degrees of importance throughout the world. Two important species in cattle—B. bigemina and B bovis —are widespread in tropical and subtropical areas. CAUSE Bovine Babesiosis (BB) is a tick-borne disease of cattle. The principal strains are babesia bovis and babesia bigemina, with Rhipicephalus ticks being the major vector. Babesia divergens is also found, with the major vector being Ixodes ricinus. BB is found in areas where its arthropod vector is distributed, especially tropical and subtropical climates. Babesia divergens is economically Ixodes ricinus Rhipicephalus ticks Transmission B. bovis takes place when engorging adult female ticks pick up the infection. They pass it on to their progeny via their eggs. Larvae (or seed ticks) then pass it on in turn when feeding on another animal. B. bigemina is also passed from one generation of ticks to the next. Engorging adult ticks pick up the infection at nymphal and adult.  Morbidity and mortality vary greatly and are influenced by prevailing treatments employed in an area, previous exposure to a species/strain of parasite, and vaccination status. In endemic areas, cattle become infected at a young age and develop a long-term immunity. However, outbreaks can occur in these endemic areas if exposure to ticks by young animals is interrupted or immuno-naïve cattle are introduced. The introduction of Babesia infected ticks into previously tick-free areas may also lead to outbreaks of disease.  Symptoms Infected animals develop a life-long immunity against re-infection with the same species and some cross-protection is evident in B. bigemina-immune animals against subsequent B. bovis infections. B. bovis Conditions are often more severe than other strains. High fever Parasitaemia (percentage of infected erythrocytes) - maximum parasitaemia is often less than one per cent. Symptoms Neurologic signs such as incoordination, teeth grinding and mania. Some cattle may be found on the ground with the involuntary movements of the legs. When the nervous symptoms of cerebral babesiosis develop, the outcome is almost always fatal. Dark coloured urine Anorexia Symptoms  Symptoms B. bigemina Fever Anorexia Animals likely to separate from herd, be weak, depressed and reluctant to move Haemoglobinuria and anaemia, Dark coloured urine Central nervous system (CNS) signs are uncommon Symptoms In B. bigemina parasitaemia often exceeds 10 per cent and may be as high as 30 per cent. Clinical symptoms for Babesia divergens are similar to B. bigemina infections. The survivors may be weak and in reduced condition, although they usually recover fully. Subacute infections, with less apparent clinical signs, are also seen.  Lesions Lesions (particularly with B bovis) include an enlarged and friable spleen; a swollen liver with an enlarged gallbladder containing thick granular bile; congested, dark- colored kidneys; and generalized anemia and jaundice. Most clinical cases of B bigemina have hemoglobinuria, but this is not invariably the case with B bovis. Other organs, including the brain and heart, may show congestion or petechiae. Diagnosis Clinically, babesiosis can be confused with other conditions that cause fever, anemia, hemolysis, jaundice, or red urine. Therefore, confirmation of diagnosis by microscopic examination of Giemsa-stained blood or organ smears is essential. From the live animal, thick and thin blood smears should be prepared, preferably from capillaries in the ear or tail tip. Babesia bovis liver smear  Microscopically, The species of Babesia involved can be determined morphologically, B bovis is small, with the parasites in paired form at an obtuse angle to each other and measuring 1–1.5 × 0.5–1 µm. B bigemina is larger (3–3.5 × 1–1.5 µm), with paired parasites at an acute angle to each other. Single forms of both parasites are also commonly seen. Babesia bigemina , bovine blood smear Babesia bovis–infected erythrocytes Diagram of various forms of Giemsa-stained Babesia bovis–infected erythrocytes. Treatment and Control A variety of drugs have been used to treat babesiosis in the past, but only diminazene aceturate and imidocarb dipropionate are still in common use. For treating cattle, diminazene is given IM at 3.5 mg/kg. At a dosage of 3 mg/kg, imidocarb provides protection from babesiosis for 4 week and will also eliminate B bovis and B bigemina from carrier animals.  Supportive treatment Anti-inflammatory drugs, corticosteroids, and fluid therapy. Blood transfusions may be life-saving in very anemic animals. Vaccination using live, attenuated strains of the parasites has been used successfully in a number of countries,. Although controlling or complete eradication of the tick vector can break the transmission cycle, this approach is rarely feasible in the long term and can lead to large, susceptible populations in endemic areas with consequent risk of outbreaks of disease in naive animals. Tick control by acaracide dipping is widely used in endemic areas.  Differential Diagnosis Babesiosis resembles other conditions that cause fever, and hemolytic anemia. The differential diagnosis includes anaplasmosis, trypanosomiasis, theileriosis, bacillary hemoglobinuria, leptospirosis, eperythrozoonosis, rape seed poisoning and chronic copper poisoning. Rabies and other encephalitides may also be considerations in cattle with central nervous system signs Babesia bigemina-infected erythrocytes Diagram of various forms of Giemsa-stained Babesia bigemina–infected erythrocytes. Note the large size of single parasites, which is rarely seen in B bovisinfections.  key point Babesia causes hemolytic anemia in bovine species. Initially, the mucous membrane becomes pale. In progressive cases, the red blood cells are lyses and bilirubin is produced as a byproduct. Also, the visible mucous membranes become yellow in color, which is called icterus.  life is an open book, Full of blank pages ,You write the story as you go...  Synopsis Etiology Babesia spp. Epidemiology Disease of tropical and subtropical countries. Occurs in cattle, sheep and goats, horses and pigs. Transmission by blood-sucking ticks. Young calves have innate resistance. Endemic stability occurs in herds with sufficient inoculation rate to immunize a high percentage of animals. Zoonotic implications Babesia bigemina and B. microti occurs i n humans where tick is found. Human donor blood may be infected. Clinical signs Anemia, hemoglobinuria, jaundice, fever, high case fatality rate, Clinical pathology Parasites in stained blood smear, positive serology. PC R for detection of parasite In blood. Necropsy lesions Thin, watery blood, pallor, jaundice. Diagnostic confirmation Parasites i n blood smear; vector present i n environment. Differential diagnosis list A syndrome of acute hemolytic anemia should suggest the following alternative diagnoses:  acute angle definition. An angle that measures less than ninety degrees but more than zero degrees. (Compare obtuse angle and right angle.) obtuse angle definition. An angle that measures more than 90 degrees but less than 180 degrees. (Compare acute angle and right angle.)