What are the Most Common Diseases in Shrimp? What are Diagnostic Test Methods for Shrimp Diseases ?

Shrimp farming is a rapidly growing industry that plays a crucial role in meeting the global demand for seafood. However, like any form of aquaculture, shrimp farming is not without its challenges. One of the primary concerns faced by shrimp farmers is the prevalence of diseases that can adversely impact shrimp health and, consequently, harvest yields. In this blog, we delve into the most common diseases affecting shrimp and explore the diagnostic test methods crucial for early detection and effective management.

What is Shrimp?

Shrimp, belonging to the order Decapoda and the infraorder Caridea, are small crustaceans with a slender body, a tough exoskeleton, and ten walking legs. Found in diverse habitats such as oceans, seas, rivers, and lakes, there are thousands of shrimp species, including common ones like white, brown, tiger, and pink shrimp. The variations in coloration are influenced by factors such as diet, habitat, and species.

Figure 1- What is Shrimp?
Figure 1- What is Shrimp?

Valued as a seafood commodity, shrimp are extensively cultivated in aquaculture farms to meet the high demand for their meat. They are an important component of the global seafood industry and are widely consumed around the world.

Types of Shrimp 

There are numerous species of shrimp, each with its own characteristics and habitats. Here are a few common types of shrimp:

1. White Shrimp (Litopenaeus vannamei): White shrimp is widely farmed globally. They are characterized by a white to grayish-green color and commonly known as Pacific white shrimp or king prawn.

2. Brown Shrimp (Farfantepenaeus aztecus): This kind of shrimp found in the Western Atlantic and Gulf of Mexico. It’s typically brown or reddish-brown in color and important for commercial fishing.

3. Tiger Shrimp (Penaeus monodon): Tiger shrimp is large and powerful shrimp species. They are recognizable by dark stripes on their exoskeleton and commonly found in the Indo-Pacific region.

4. Pink Shrimp (Pandalus borealis): Pink shrimp usually refers as cold-water shrimp inhabiting the North Atlantic. It has pink to light reddish-brown in color. And it is popular species in Northern European cuisine.

Figure 2- Types of Shrimp
Figure 2- Types of Shrimp

5. Rock Shrimp (Sicyonia brevirostris): Rock shrimp found in the western Atlantic Ocean. It is named for its hard exoskeleton resembling a small rock. Generally harvested for commercial use.

6. Spot Prawn (Pandalus platyceros): It is native to the North Pacific and identified by distinctive white spots on their bodies. Spot Prawn type is highly valued for their sweet taste.

7. Harlequin Shrimp (Hymenocera elegans): This kind of shrimp is small, colorful shrimp with vibrant patterns and found in the Indo-Pacific region. It is known for their unique appearance and symbiotic relationship with sea stars.

8. Cherry Shrimp (Neocaridina davidi): Cherry shrimp is freshwater shrimp commonly kept in aquariums. It has various color variations, including red, blue, and yellow. And it’s hardy and popular among aquarium enthusiasts.

9. Amano Shrimp (Caridina multidentata): Amona shrimps is freshwater shrimp native to Japan. It is often used in aquariums for algae control. It is transparent with brown or green markings.

10. Ghost Shrimp (Palaemonetes spp.): Ghost shrimp is small, transparent freshwater shrimp and commonly used in aquariums as scavengers. It is found in various regions worldwide.

These are just a few examples, and there are many more species of shrimp with diverse characteristics and habitats. Shrimp play a crucial role in both marine ecosystems and the global seafood industry.

Shrimp Production and Consumption Worldwide:

Shrimp is a highly sought-after seafood globally, and the industry has experienced significant growth over the years. Countries such as China, India, Vietnam, Indonesia, and Thailand are major contributors to the world’s shrimp production. The consumption of shrimp is prevalent in various cuisines, contributing to the industry’s economic significance.

Figure 3- Shrimp aquaculture production in major farming nations in Asia.
Figure 3- Shrimp aquaculture production in major farming nations in Asia.

Shrimp Farms:

Shrimp farms are distributed across the globe, often situated in coastal regions with favorable environmental conditions. These farms vary in scale, from small-scale operations to large, industrial-sized facilities. The distribution of shrimp farms is influenced by factors such as climate, water quality, and accessibility to markets. 

Most Common Diseases in Shrimp

Shrimp diseases can be caused by bacterial, viral, and fungal pathogens. Each type of pathogen poses unique challenges to shrimp farming, requiring specific diagnostic methods and management strategies.

  1. White Spot Syndrome (WSS): White Spot Syndrome is one of the most notorious and widespread diseases in shrimp farming. Caused by a virus known as White Spot Syndrome Virus (WSSV), this disease leads to the development of small, white spots on the exoskeleton of infected shrimp. WSS can spread rapidly, causing high mortality rates and significant economic losses for shrimp farmers.
  2. Early Mortality Syndrome (EMS): Also known as Acute Hepatopancreatic Necrosis Disease (AHPND), Early Mortality Syndrome is a bacterial disease that primarily affects the hepatopancreas of shrimp. EMS emerged as a significant threat to the shrimp industry in recent years, causing severe mortality among affected populations. Vibrio parahaemolyticus, a bacterium, is identified as the primary causative agent.
  1. Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV): IHHNV is a viral disease that primarily affects the hemocytes and hypodermis of shrimp. It can cause a variety of symptoms, including color changes, slow growth, and a reduction in overall shrimp health. IHHNV is particularly concerning as it can lead to secondary infections, exacerbating the impact on shrimp populations.
  2. Taura Syndrome Virus (TSV): Taura Syndrome is a viral disease that affects the hepatopancreas of shrimp. It is caused by Taura Syndrome Virus, which can lead to severe mortality in shrimp populations. Infected shrimp typically exhibit lethargy, darkened coloration, and a decrease in feeding activity.
  3. Infectious Myonecrosis (IMN): Infectious Myonecrosis is a viral disease that affects the muscle tissue of shrimp. It can cause white, opaque areas in the muscle, leading to a condition known as “white tail disease.” IMN can spread quickly within shrimp farms, and its impact on muscle tissue quality poses a significant economic threat to the industry.
  4. Yellow-Head Disease (YHD): Yellow-Head Disease is a viral infection that targets the cephalothorax and gills of shrimp. Infected shrimp often display a yellow discoloration of the head, leading to high mortality rates. YHD poses a significant threat to shrimp farming, necessitating effective biosecurity measures and management strategies.
  5. White Feces Syndrome (WFS): White Feces Syndrome, characterized by the presence of white-colored feces in infected shrimp, is associated with viral and bacterial agents. The syndrome can lead to slow growth, decreased feeding, and increased mortality, underscoring the importance of proactive disease management.
  6. Covert Mortality Nodavirus (CMNV): Covert Mortality Nodavirus, a viral disease affecting shrimp, induces covert mortalities with minimal external signs. The virus targets the nervous system, leading to neurological symptoms and eventual mortality. Managing CMNV requires vigilant monitoring and biosecurity measures to prevent its spread.

Transmission and Prevention

Shrimp diseases can spread through direct contact (horizontal and vertical transmission), waterborne pathways, fecal-oral routes, and vectors. Human activities and biosecurity lapses contribute to disease transmission, while environmental factors and trade play roles in prevalence. Managing shrimp diseases necessitates a holistic approach, including biosecurity measures, regular monitoring, and disease-resistant shrimp breeds.

Treatment Methods

Treating shrimp diseases involves diverse strategies, with antibiotics or antimicrobials targeting bacterial infections. Antiviral agents may be used for viral diseases, while probiotics and immunostimulants enhance overall health. Disinfection, water management, quarantine, and biosecurity practices help control disease spread. Selective breeding for disease-resistant strains, environmental and nutritional management, contribute to long-term health. Integrated approaches, tailored to specific diseases, are crucial, and expert consultation ensures accurate diagnosis and effective treatment.

What are Shrimp Diseases Diagnostic Test Methods?

Diagnostic testing for shrimp diseases plays a crucial role in identifying and managing health issues within shrimp populations. Several methods are employed to diagnose various diseases affecting shrimp in aquaculture. Here are some common diagnostic test methods:

  1. Histopathology:
    • Histopathology involves examining thin sections of shrimp tissues under a microscope to identify abnormalities or lesions caused by pathogens. This method helps determine the specific disease and its impact on shrimp organs.
  2. PCR (Polymerase Chain Reaction):
    • PCR is a molecular biology technique used to amplify and analyze DNA. In shrimp disease diagnostics, PCR can detect the presence of specific pathogens by amplifying their genetic material. This method provides highly specific and sensitive results.
  1. ELISA (Enzyme-Linked Immunosorbent Assay):
    • ELISA is an immunological assay that detects the presence of antigens or antibodies in shrimp tissues. It is commonly used to identify viral infections, providing a rapid and accurate diagnosis.
  2. Immunoassays:
    • Immunoassays, including lateral flow devices, detect specific proteins associated with shrimp pathogens. These tests are often quick and can be performed on-site, making them useful for routine health monitoring.
  3. Bacterial Culture:
    • Bacterial culture involves isolating and growing bacteria from shrimp tissues to identify the causative agent of bacterial infections. This method helps determine the appropriate antibiotic treatment.
  4. Gross Pathology:
    • Visual examination of shrimp for external signs of disease, such as abnormal coloration, lesions, or deformities, is a basic diagnostic approach. While it may not provide detailed information, gross pathology is often the first step in disease detection.
  5. Hematology:
    • Hematological analysis involves studying the blood of infected shrimp to identify abnormalities in cell count, morphology, or biochemistry. Changes in blood parameters can indicate the presence of certain diseases.
  6. In-situ Hybridization:
    • In-situ hybridization is a molecular technique that allows the visualization of specific RNA or DNA sequences within shrimp tissues. This method aids in locating the distribution of pathogens in infected organisms.
  7. Serology:
    • Serological tests, such as agglutination tests, detect antibodies or antigens in the blood of infected shrimp. These tests provide information about the immune response and aid in diagnosing various diseases.
  8. Genomic Sequencing:
    • Genomic sequencing involves determining the entire genetic code of a pathogen. This advanced method provides detailed information about the genetic makeup of the infectious agent, aiding in strain identification and epidemiological studies.

Effective disease management relies on accurate and timely diagnosis. Integrating multiple diagnostic methods based on the nature of the disease and the available resources ensures a comprehensive understanding of the health status of shrimp populations in aquaculture.

In conclusion, the health of shrimp in aquaculture is paramount to ensuring sustainable and profitable farming. Understanding the common diseases in shrimp and employing effective diagnostic test methods are crucial steps toward maintaining a healthy shrimp population. Early detection allows for timely intervention, reducing the impact of diseases and safeguarding the success of shrimp farming operations. As the industry continues to evolve, staying informed about the latest diagnostic technologies is key to overcoming the challenges posed by shrimp diseases.

REFERENCES

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