Yellow Head Disease of Shrimp

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Yellow head disease of shrimp is a viral disease that affects shrimp. The yellow head virus causes the shrimp to develop a yellow head and eventually die.

The black tiger shrimp (prawn), Penaeus monodon, is a major aquaculture species that is infected by the yellow head virus (YHV).

The virus can be deadly to shrimp populations and can cause significant economic losses for shrimp farmers. It has a high mortality rate (100%) within a few days following the onset of symptoms in a pond.

The article briefly describes the yellow stuff in shrimp heads and its precautions.

Yellow Head Disease of Shrimp
Image source: semanticscholar.org

Causes of Yellow Head Disease

The causative agent of yellow head disease is a virus. The virus is classified in the order Nidovirales, genus Okavirus, which is in the family of Coronaviridae.

It is a positive-sense, rod-shaped, single-stranded RNA (ssRNA), an enveloped virus that is enveloped and has a cytoplasmic location.

Yellow Head Virus (YHV), has been identified in pond-raised shrimp farms that raise P. monodon, i.e. mainly in Southeast Asian farms.

History of Yellow Head Virus

YHD was first observed in Thailand in 1990 and later spread throughout Asia and America. The virus is believed to be spread through contact with other infected shrimp or with water that has been contaminated with the virus.

The disease causes the heads of infected shrimp to turn yellow, and the shrimp eventually die. It creates significant losses to the shrimp farming industry, and there is currently no cure or prevention for it.

Transmission

YHV has been detected in a wide range of aquatic and terrestrial invertebrates and is known to cause high mortality rates in shrimp and crabs.

These include cannibalization of infected animals,

Diseased shrimp, carcasses, and smaller pieces of flesh from dead shrimp can serve as vectors of the yellow head virus.

Exposure to contaminated water or sediment, feeding on infected prey and viral particles may spread the disease.

This virus can cause significant mortalities in farmed shrimp populations. It is therefore important to understand the means by which this virus is transmitted in order to minimize its impact on commercial shrimp production.

Geographic Distribution and Host Range

The virus is endemic to Black tiger shrimp of the Indo-Pacific region having a complex genotype.

The disease conditions were observed in Thailand, Taiwan, China, Malaysia, Indonesia, Philippines, Vietnam, Madagascar, India, and Sri Lanka.

Pacific white shrimp (Litopenaeus vannamei), Pacific blue shrimp (Litopenaeus stylirostris), brown tiger shrimp (Penaeus esculentus), white banana shrimp (Fenneropenaeus merguiensis), white shrimp (Litopenaeus setiferus), brown shrimp (Farfantepenaeus aztecus), hopper and brown-spotted shrimp (Farfantepenaeus duorarum), and red endeavour prawn (Metapenaeus ensis), and Jungas shrimp (Metapenaeus affinis) were also affected with this virus (Walker, P. J., & Sittidilokratna, N., 2008)

Yellow Head Virus Symptoms

The symptoms of yellow head disease in shrimp are usually easy to identify.

YHV infection in shrimp occurs in late postlarval stages, but mass mortality usually occurs in the early to late juvenile stages. Disease and mortality usually occur within 2 to 4 days.

-The shrimp become lethargic and lose their appetite. They then start to develop a yellow color around their heads, followed by death.

-The hepatopancreas becomes yellow because of lesions in the yellowing of the skin covering the cephalothorax.

-Moribund shrimp gather near pond edges near the surface of the water.

Diagnosis For Yellow Head Virus Disease in Shrimp

Erratic swimming behavior might not export the symptoms of YHV infection. To be useful for disease diagnosis, current signs should be observed.

Moderate to high numbers of basophilic, spherical, cytoplasmic inclusions in tissues of ectodermal and mesodermal origin are indicative signs of YHV infection.

Electron microscopy or molecular lab tests, such as reverse transcriptase-polymerase chain reaction (RT-PCR) or in situ hybridization assays, are used for confirmatory diagnosis of yellow head disease.

Yellow Head Virus Treatment

There is no specific treatment for yellow head virus infection in shrimp, so the best way to prevent losses is to ensure good biosecurity measures are in place.

This includes using appropriate disinfectants and clean water supplies and separating infected from healthy animals.

Frequently Asked Questions

Is yellow shrimp bad?

Some sources recommend avoiding eating yellow head shrimp altogether, while others claim that they are safe as long as they are cooked properly.

Final Words

Yellow Head Disease (YHD) is a viral disease of shrimp that can cause high levels of mortality. The virus is believed to be spread through water and can cause lesions on the shrimp’s head, body and tail.

Infected shrimp often have a yellow discoloration on their heads. YHD has been reported in many countries around the world and can cause significant losses in commercial shrimp farming operations.

There is no cure for YHD, and it is currently not possible to prevent its spread. As a result, controlling the spread of the virus is critical for preventing outbreaks.

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