Muhammad Noman Naseema, Muhammad Kashif Saleemia, Aisha Khatoona, Rao Zahid Abbasb
a Department of Pathology, University of Agriculture Faisalabad, Pakistan.
Poultry industry is 2nd largest industry of Pakistan after textile, growing with the growth rate of 10-12% annually. Poultry is cheap and major animal protein source of Pakistan as compared to other. 40-45% percent of total meat consumption is being produce from poultry products. Annually we are producing 18,000 million table eggs and 2,250 million kilo grams chicken meat. As poultry is our major protein source, some risk factors may associate with poultry. One of them is zoonosis.
The word zoonosis refers to diseases and infections which are transmitted from animals to humans. The infectious agent may be a Virus, Bacteria, Fungi, Parasite or Toxin. For a disease to happen, disease causing agent must require a suitable host and environment, to control a disease one must break links in this triad. Inhalation, ingestion, direct contact, absorption through skin or mucous membrane and injection through bite are most probable routes of zoonosis.
Most common zoonotic threats from poultry are Avian Influenza, Salmonellosis & Compylobacteriosis, Avian Tuberculosis, Histoplasmosis, Chlamydiosis, Newcastle Disease, Collibacilosis and West Nile Virus.
Avian Influenza
Organization international epizootic (OIE) classify it as list A disease (diseases which are highly pathogenic and don’t observe the boundaries). It has very high socio-economic value, significant public health hazard and this also influences the international trade of poultry and poultry products. AI is caused by a single stranded RNA virus, Type A Orthomyxovirus having 8-segmented genome. Highly Pathogenic Avian Influenza (HPAI) causes sudden death in birds without clinical signs. Dead birds have varies congestion and hemorrhage in multiple tissues.
In Human, HPAI may cause severe respiratory signs such as cough, sore throat and pneumonia. Fever and eye infection also observed in human. Working with infected flock or eating raw, uncooked poultry meat may become source of infection for human.
Salmonellosis & Compylobacteriosis
In USA, Salmonellosis and Compylobacteriosis are ranked 1St and 2nd respectively in causing food borne gastroenteritis in human, while in Europe, Compylobacteriosis is on top. Human cases are mostly caused by zoonotic pathogens including non typhoidal Salmonella such as Salmonella Enteritidis, Salmonella Typhimurium and Campylobacter Jejuni. The most suspected routes of these two infections to human are, eating contaminated poultry meat and eggs or contamination while handling of poultry or poultry product. In United States, a survey was conducted between 1998 to 2008, revealed that Salmonella and Campylobacter are causes almost 1.8 million foodborne infections in human each year. Between this time periods, it was observed that all foodborne diseases outbreak were 20% shared by Salmonella and 16% by Campylobacter.
Human infections with non-typhoidal Salmonella (NTS) serovars are increasingly becoming a threat to human health globally. While all motile Salmonellae have zoonotic potential, Salmonella Enteritidis and Salmonella Typhimurium are most commonly associated with human disease, for which poultry is a major source. In infected birds, ruffled feathers, diarrhea, droopiness, severe lethargy, incoordination and convulsion is mostly observed. Liver become swollen with whitish foci and may have bronze color appearance.
In Human, source of infection is eating contaminated poultry products or inadequate hand washing after dealing with infected poultry. Diarrhea, fever, and abdominal cramps 12 to 72 hours after infection are observed. Illness usually lasts for 4 to 7 days.
Avian Tuberculosis
Tuberculosis in birds is caused by Mycobacterium avium, closely to human and bovine tuberculosis bacteria. This bacteria cause chronic debilitating disease in birds with tubercles nodules on different organs.
This disease is transmitted to human through eating of raw or improperly cooked poultry meat. The disease is most severe in immune compromised people causing swelling of regional lymph nodes.
Histoplasmosis
Histoplasmosis is caused by Histoplasma capsulatum that grow in soil contaminated birds or bat droppings. This is mostly found in damp poultry house litter. Birds do not show any disease sign but their droppings are major nutrient source for growth of this organism. Birds may carry this microorganism on their wings, feet and beaks.
Transmission of disease to human occurs through inhalation of spore. Farmers and laboratory staff are more prone to infection. Disease primarily affects the lower respiratory system. Mild flue like symptoms appears after 3-17 days of exposure of causative organism. Infants, young children, and older persons, in particular those with chronic lung disease are at increased risk for severe disease.
Chlamydiosis or Psittacosis
Chlamydiosis or psittacosis is a reportable disease, in USA 923 cases reported to CDC from 1988 to 2002. Psittacosis is caused by a rekittseal microorganism known as Chlamydia psittica, which is an intracellular microorganism present in feces and nasal discharge of the infected birds. Almost all birds are susceptible and disease present worldwide. Carrier birds appear healthy but can shed the organism. Shedding of organism tremendously increase during stress period.
In birds, disease ranges from inapparent to severe, causing high mortality. Birds may become anorexic, lethargic and have ruffled feather appearance with serous or mucopurulent ocular and nasal discharges. Sometimes diarrhea, excretion of green to yellow green urates also seen. Birds may die soon after onset or become emaciated or dehydrated before death. During postmortem examination of birds, enlargement of spleen, liver, pericarditis and congestion of lungs and air sacs can be examined.
In human, disease is transmitted through inhalation of microorganism. The farm personnel’s handling with infected bird plumage and tissues are more prone to psittacosis infection. Clinical sings appear 5-14 days after exposure and mostly limited to respiratory tract including flue, non-productive cough and pneumonia. Sometimes severe systemic illness is also observed.
Newcastle Disease
Newcastle disease (ND) is one of the most deadly diseases of poultry around the globe. The disease is endemic in Pakistan and recurrent outbreaks are being reported regularly in wild captive, rural and commercial poultry flocks.
Newcastle disease is caused by APMV-1. Valogenic strains effect respiratory, digestive and nervous system, causing high mortality at poultry farm. Clinical signs in birds includes uncoordinated movement, head twisted over back, weakness, muscle tremors, paralysis of one or both wings and legs. During necropsy examination, multiple hemorrhages in proventricular mucosa, raised ulcers in intestine and congestion or hemorrhages on ceacal tonsils along with trachitis and air sacculitis also observed.
In human, people dealing with infected poultry flock or disposal of mortality are at high risk of zoonosis. Infection is mostly self-limiting in human, with conjunctivitis and mild flue like symptoms.
Colibacillosis
E.coli is normal inhabitant of intestinal tract of poultry. Different strains of E.coli present in poultry, not all are pathogenic and many of them are species specific. In birds, cause Septicemia, chronic respiratory disease, synovitis, pericarditis, peri-hepatitis and salpingitis.
In human, disease mostly food borne or water borne, transmitted through fecal-oral route. IP- 12 hours to 5 days, most common 12-72 hours and disease is manifested with diarrhea, fever, dysentery, shock and purpura.
West Nile Virus
West Nile virus is a single stranded RNA virus belongs to genus flavivirus. Almost all mammals are susceptible to this infection but birds act as reservoir of this. Mode of transmission is mostly mechanical through mosquitoes especially by culex species. Mostly birds died without showing any signs, those who remain alive are emaciated, show trembling, difficulty in balance, inability to fly, stand or perch, unafraid of humans, and may be blind. Inflammation of heart and brain can be observed in dead birds upon necropsy examination.
In human almost 80% cases are asymptomatic, while 20% cases show clinical sigs after 3-14 days of post exposure of virus. These include flu-like symptoms including fever, fatigue, headache, muscle or joint pain. There is less than 1% chance of West Nile Meningitis, West Nile Encephalitis, and West Nile Poliomyelitis. In severe form, high fever, stiff neck, disorientation, tremors, muscle weakness, paralysis can be seen. Disease may become highly fatal in severe form.
Minimizing Risk to Human
Most zoonosis are preventable if cautionary measures are taken properly. The risk to human can be minimized by adopting the following measure.
Personnel Protection
The persons working at farm or dealing with live or dead poultry are at high risk of zoonosis. To prevent zoonosis or to minimize zoonosis risk, one should adopt best personnel protection available. Do not eat, drink, apply makeup or use tobacco products while handling poultry or in poultry housing area. During routine handling of poultry, one must adopt level “D” personnel protective equipment (wear glove, disposable masks, protective clothing or lab coat and closed shoes) while if dealing with a zoonotic disease outbreak in poultry, level “C” personnel protective equipment (three layers of gloves, N95 mask or APR with N95 0r N100 filters, protective clothing, head cover or protective cap, eye protection or goggles and gumboots) must be used. Person dealing with zoonotic disease outbreak must be trained of proper donning and doffing protocol. Wash hands in warm soapy water and disinfect using germicidal compounds. Disinfect boats and vehicles as necessary. Wash bag clothing as soon as possible in warm or hot water, separate from your personal clothes and preferably at the poultry farm facility.
Disinfection and Disposal
Keep animal areas clean and disinfect equipment after using it on farms. Dispose of mortality carefully at recommended site and must remove mud and muck before disinfectant. Cleaning and disinfection should be done thoroughly and as soon as possible. All equipment must be removed after every flock, clean and disinfected with formalin spray or glutaryl aldehyde solution. Fumigation of building and equipment’s must be recommended before putting new flock in house. Wet down dry, dusty areas or area with bird droppings by using disinfectant.
Prevent mechanical transmission of disease agents
Some diseases such as psittacosis are mechanically transmitted through mosquitoes bite. To control such diseases, mechanical transmission should be minimized. This can be done by minimizing exposure to insect bite through use of insect repellent or protective clothing. Efforts should be done to eliminate mosquitoes breeding area at the farm. Vector control programs including insecticide spraying, draining of wetlands can also be launched in a society.
Discouraging the Live Bird market
Another modern method to control zoonosis is transition of live bird market to process meat and meat products. This will reduce the risk of food borne zoonosis such as salmonellosis, compylobacteriosis and collibacilosis.
Medical Care
The person dealing with poultry or working at poultry farm must be familiar with zoonotic diseases that he may encounter. If infection occurs, use anti-viral, antibacterial, anti-fungal and supportive therapy as recommended by physician. Follow up physician on regular bases for routine checkup. Make sure your health professionals know you work with poultry.
