Highly Pathogenic Avian Influenza (HPAI) continues to be a problem in various parts of the world, though it has been overshadowed in the news by other diseases such as H1N1 "Swineflu", Ebola and Middle East Respiratory Syndrome (MERS). In recent weeks, serotypes H5N8 and the notorious H5N1 have been detected in a few countries.
According to the latest disease report from the World Organization for Animal Health (OIE), there are occurrences of HPAI being dealt with in the United Kingdom (H5N8, under control), the Netherlands (H5N8, under control), Japan (H5N8 - wild birds only), India (H5N1) and most recently Canada (H5, reported on December 3, identification incomplete). The approach to outbreaks continues to be stamping out (destruction of infected flocks) and close monitoring.
According to the latest report from the World Health Organization (WHO), only one human case of H5N1 has been diagnosed in the period July-October 2014 - a 2-year old child in Egypt. Since 2003, there has been a total of 668 laboratory confirmed cases of H5N1 in humans in 16 countries with 393 deaths. H5N8 has not been documented in humans.
HPAI has not been detected in Jamaica but surveillance is continuous.
For the OIE's technical data sheet on HPAI, please click HERE .
Highly Pathogenic Avain Influenza H5N2 outbreak in the USA
Highly pathogenic avian influenza (HPAI) H5N2 has been affecting a number of states in the United States over the past two weeks. Outbreaks have occured in poultry and/or turkey farms in Minnesota, Missouri and Arkansas. This follows the detection of the virus in wild birds and backyard flocks in Washington State and Oregon in recent months. It is thought that the virus is spreading through wild bird migration via the Mississippi Flyway. Affected farms have been quarantined, with depopulation and disinfection ensuing.
No human cases of this Birdflu strain have been detected and the US Centers for Disease Control (CDC) considers the risk of such cases to be low. Nevertheless, because the virus can be spread mechanically via contaminated materials, the USDA/APHIS in a release is advising that persons "should avoid contact with sick/dead poultry or wildlife. If contact occurs, wash your hands with soap and water and change clothing before having any contact with healthy domestic poultry and birds. All bird owners, whether commercial producers or backyard enthusiasts, should continue to practice good biosecurity, prevent contact between their birds and wild birds, and report sick birds or unusual bird deaths to State/Federal officials..."
In Jamaica, our Veterinary Services Division and poultry industry are on alert and carefully monitoring the situation. At this time of year, migratory birds are traveling northwards so, for now, there is little risk from them. No cases of HPAI of any strain have been detected in Jamaica.
UPDATE: The Veterinary Services Division of the Ministry of Agriculture & Fisheries has imposed a ban on poultry and poultry products originating in the US States of Kansas, Arkansas, Missouri, Minnesota, California, Idaho, Oregon and Washington and the Canadian Province of British Columbia. This does not apply to canned, fully cooked or commercially sterilized products.
Chicken Infectious Anaemia (Blue Wing Disease) is a viral disease of chickens caused by the Chicken Anaemia Virus (CAV). It is caused by a Gyrovirus of the family Circoviridae and was first isolated in Japan in 1979, but is now known to occur worldwide. Clinical disease occurs in chickens but infection has been detected in turkeys and quail3.
It can infect chickens of any age but clinical disease is generally seen in the first two weeks of life1, with birds becoming more resistant as they get older. However, concurrent infections with immunosuppressive agents such as Infectious Bursal Disease or Marek’s Disease viruses may compromise the development of age resistance3. Transmission is both vertical and horizontal with chicks hatched from infected eggs being viremic and spreading virus to uninfected chicks via faeces and feathers3. Infected roosters may transmit virus via semen3. Infected older birds will undergo seroconversion and become immune3. Seroconverted breeders will pass protective antibodies to their chicks which will not, therefore, develop clinical disease.
The virus primarily affects the immune and haemopoietic systems, particularly invading the thymus. This results in decreased T-lymphocytes and red blood cells in circulation.
Clinical signs of illness4 include pallor, depression and poor growth.. There may be a significant and sudden rise in mortality usually at about 2 weeks of age. Subcutaneous haemorhages may be seen on the wings and hock joints causing a bluish discolouration (hence the name Blue Wing Disease). Hematocrits may be in the 5-15% range (normal 27-36%). Immunosuppression may lead to opportunistic infections such as gangrenous dermatitis and mycotic pneumonia. Infected adult birds will show no clinical signs.
Post mortem lesions4 include overall pallor, thymic and bursal atrophy, pale bone marrow and discoloured liver and kidneys. Haemorhages in the proventriculus may be seen. Signs of gangrenous dermatitis or pneumonia may be present. Histological examination of thymus or bursa of Fabricius will show depletion of lymphocytes.
Diagnosis is based on post mortem findings and serological or PCR testing1,3,4. CAV monitoring is carried out in Jamaica using an ELISA test from IDEXX Laboratories.
There is no treatment. Secondary bacterial infections may be treated with the appropriate antibiotics.
Prevention strategies include vaccination and general hygiene. Live attenuated vaccines are used for either injection or drinking water administration for breeder flocks prior to the start of laying. This is usually done between 12 and 15 weeks of age to allow time for seroconversion2. Direct use of infected material (litter or tissue homogenates from infected birds) to infect flocks prior to breeding, again allowing time for seroconversion, has also been used. Serological testing may be used to ascertain seroconversion.
In Jamaica, broiler breeder and layer pullets are routinely vaccinated against the Chicken Anemia Virus and thus it has not been a significant problem for the poultry industry. Nevertheless, it is one of the diseases that must be considered when dealing with cases of mortality in young growing chickens.
A haemorrhagic lesion on the wing of a chicken infected with the Chicken Anaemia Virus (http://www.chicken-anemia.com)
Echhymotic haemorrhages on the inner wing surface of an affected chicken (http://www.chicken-anemia.com/)