Hemorrhagic Septicemia their Etiology, Diagnosis, Treatment and Vaccine.
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INTRODUCTION:
Hemorrhagic septicemia is acute, fatal septicemia (presence in blood) disease of cattle and buffaloes caused by Pasteurellosis multocida serotype B2 that belong to family. Pasteurellosis multocida serotype B: 2 cause the disease in Asia, the Middle East and some southern European countries, while serotype E: 2 is the cause in Africa. They are gram negative chemoorganotrophic, facultative anaerobic, fermentative bacteria, non-motile, non-spore-forming, short rod or coca-bacillus size range 0.2-0.4 by 0.6-2.5um.The family has three genera: Pasteurellosis, Actinobacillus, and Haemophilus. Many other species that includes Pasteurella haemolytica,P. pneumotropica, P. gallinarum, P. ureae, and the gas-producing, Â P. aero genes, P. multocida has three subspecies: multocida, septica, and gallicida.
They are classified into five capsular antigen A, B, D, E, and F and 1-16 somatic antigen. More than 1000 serotypes present. Â Definite host of HS are cattle and buffaloes, but it may be suspected in goat, sheep, pigs, horse, donkeys, camels, yaks, and poultry. Buffaloes tend to be more susceptible to the disease than cattle.
All ages can be affected but in endemic areas the disease is most common in animals between 6 and 24 months of age. Older animals may have a degree of immunity from previous exposure.
ETIOLOGY
Pasteurella multocida:
The primary causative agent of HS, Pasteur Ella multocida, is a Gram-negative bacterium commonly found in the respiratory tracts of healthy animals. Under conducive conditions such as stress, overcrowding, or transportation, the bacterium can proliferate rapidly, leading to disease manifestation. Transmission: HS spreads through direct contact with infected animals, contaminated environments, or through aerosols expelled during coughing or sneezing. Additionally, vectors like flies can mechanically transmit the bacteria, exacerbating the spread.
Effects on Animals:
Acute Clinical Signs:Â
Affected animals often exhibit sudden onset fever, depression, loss of appetite, difficulty breathing, and nasal discharge tinged with blood. In severe cases, they may develop characteristic hemorrhagic lesions in the lungs and other organs.
Infected fish often display a range of symptoms, including lethargy, loss of appetite, skin lesions, hemorrhages, abdominal distension, and in severe cases, death. Hemorrhages may occur internally or externally, leading to reddish discoloration of tissues.
High Mortality Rates:Â
HS can be swift and deadly, with mortality rates reaching up to 90% in untreated animals. The disease progresses rapidly, and affected animals may die within 24 to 48 hours of onset.
Economic Losses:Â
HS outbreaks can devastate livestock populations, resulting in significant economic losses for farmers and stakeholders. Besides mortality, survivors may suffer reduced productivity, such as weight loss, decreased milk production, and compromised reproductive performance.
GLOBAL DISTRIBUTION:
Globally distributed except UK, Australia, and some European countries but endemic in Asia and Africa. The disease was first reported in 1880s in Malaysia.
CAUSES:
 The main causes of hemorrhagic septicemia include:
 Pasteur Ella multocida bacteria infect the respiratory tract, leading to hemorrhagic pneumonia. Stress Environmental stressors such as overcrowding, transportation, or sudden changes in weather can weaken the immune system, making animals more susceptible to infection.
 Inadequate ventilation, hygiene, or nutrition can predispose animals to infection
 Young animals, pregnant animals, or those with pre-existing respiratory conditions are more vulnerable to the disease.
Lack of vaccination or ineffective vaccination programs can leave animals unprotected against the disease.
SIGN AND SYMPTOMS:
 HS mostly occurs in buffaloes because they are susceptible. Clinical symptoms include high temperature, loss of appetite, nasal discharge, and increased salivation, breathing and swelling on submandibular site. Death usually occurs hastily, and mortality is 100% in infected animals. Recovery from clinical disease occurs only if the animal is treated in the very early stages but is totally impossible. The incubation period of the disease is 2 to 4 days and the course ranges from 2 to 5 days.
Effects on Humans:
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Zoonotic Potential:Â
While rare, Pasteur Ella multocida can infect humans, primarily through contact with infected animals or their secretions. Human cases usually occur in individuals with compromised immune systems or those involved in close contact with infected animals, such as veterinarians, farmers, or abattoir workers.
Manifestations:Â
In humans, HS can manifest as localized wound infections, pneumonia, septicemia, or meningitis. Prompt medical intervention with appropriate antibiotics is crucial to prevent severe complications.
Preventive Measures:
 To minimize the risk of zoonotic transmission, individuals working with animals should practice strict hygiene protocols, including hand washing, wearing appropriate personal protective equipment (PPE), and promptly treating any injuries sustained during animal handling.
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GROWTH CHARACTERISTICS:
 Mostly grow in nutrient agar. Special media for growth are dextrose -starch agar and casein-sucrose-yeast. These media are available for abundant growth. Blood agar with 5% (sheep or bovine blood) used. Hemolysis on blood agar never occurs. Never grow on MacConkey agar. Idol production, catalase, and oxidase positive.  Optimum temperature is 35-37 Celsius and incubated for 24 hours. Its colonies character depends upon the capsular type of bacteria like capsular type a produces the largest colonies, which are translucent, greyish in color, and fucoid in consistency.
DIAGNOSIS:Â
A history of acute disease with high mortality in areas where hemorrhagic septicemia is endemic may suggest a presumptive diagnosis of the condition. Diagnosis of hemorrhagic septicemia in fish involves clinical examination, observation of typical symptoms and laboratory tests such as bacterial culture and PCR (Polymerase Chain Reaction) assays to identify the presence of Pasteur Ella pesticide.
. • Gross pathological changes may include widespread petechial hemorrhages, enlarged hemorrhagic lymph nodes and blood – tinged fluid in the pleural cavity and the pericardial sac.
- Gyms – stained blood smears from a recently dead animal often reveal large numbers of bipolar – staining organisms.
- Isolation, identification and serotyping the P. multocida isolate are confirmatory. Serotypes B: 2 and E: 2 are the specific strains associated with the disease. A multiplex PCR method for identification of serotypes described by Townsend teal. (2001) has replaced the traditional indirect haemagglutination assay in many laboratories.
. • An antibody titer of 1:160 or above in an indirect hem agglutination test is indicative of recent exposure to the pathogen.
TREATMENT AND CONTROL:Â
Antibiotic therapy in the early febrile stage is usually effective. Although the organism is susceptible to penicillin, tetra-cyclones are more often used.
Treatment options for hemorrhagic septicemia in fish include antibiotics, although efficacy can vary depending on the stage of infection and fish species involved. Prevention measures include maintaining optimal water quality, avoiding overcrowding, quarantine of new fish arrivals, and vaccination where available.
.A slaughter policy for affected and in – contact animals is usually pursued in countries where the disease is exotic.
- Vaccines available for control of the disease include bacteria and a live heterotypic vaccine (Mint and Carter, 1989). Modified live deletion mutant vaccines have been developed also (Dallies teal. 2007).
- Latent carriers can be detected using immune-his to chemical techniques on samples of tonsillar tissue.
Prevention and Control:
Vaccination:Â
Vaccination plays a crucial role in preventing HS outbreaks in susceptible animal populations. Several commercially available vaccines provide protection against specific serotypes of Pasteur Ella multocida.
Biosecurity Measures:
 Implementing robust biosecurity protocols on farms, including quarantine procedures for new animals, maintaining clean and well-ventilated housing facilities, and controlling vectors like flies, can help reduce the risk of HS transmission.
Early Detection and Treatment:Â
Timely diagnosis and prompt treatment with appropriate antibiotics are essential for managing HS outbreaks. Veterinarians play a pivotal role in conducting surveillance, diagnosing cases, and implementing control measures to mitigate the spread of the disease.
Economic Impact:
 Hemorrhagic septicemia can have significant economic implications for aquaculture operations due to mortality, decreased growth rates, and costs associated with treatment and prevention measures.
 Hemorrhagic septicemia poses significant challenges to both animal health and public health. Understanding its etiology, clinical manifestations, and preventive measures is crucial for effective disease management and control. By implementing comprehensive strategies encompassing vaccination, biosecurity, and early intervention, stakeholders can minimize the impact of HS on livestock populations and mitigate the risk of zoonotic transmission to humans.Â
Hemorrhagic septicemia primarily affects animals, particularly cattle, buffalo, and other ruminants, and is caused by the bacterium Pasteur Ella multocida. While it is rare for humans to contract hemorrhagic septicemia directly from infected animals, transmission can potentially occur through contact with contaminated tissues or fluids during handling or processing of infected carcasses. However, human infections are exceptionally uncommon and typically only occur in individuals with compromised immune systems or pre-existing health conditions.
 To minimize the risk of transmission, proper hygiene practices, including wearing protective gear and thoroughly washing hands and equipment after handling potentially infected animals or tissues, are essential.
