Hepatitis in slaughterhouse workers

Hassan Tariq, Muhammad Umar Kamal, Jasbir Makker, Sara Azam, Usman Ali Pirzada, Vaniza Mehak,Kishore Kumar, Harish Patel

Abstract Slaughterhouse workers (SHW) are at increased risk of hepatitis which can occur due to different organisms and should be investigated for viral, bacterial, and parasitic organisms. Slaughter house personnel including butchers are at a higher risk of infections from cuts and blood-letting, with the possible risk of the transmission of blood-borne pathogens to their colleagues. The objective of this review is to evaluate the common etiologies of hepatitis in SHW which will assist in the assessment of these patients presenting with transaminitis. Types of Microorganisms causing hepatitis with their reservoirs, routes of transmission,laboratory diagnosis, clinical features, treatment options and preventive strategies are included in this review. Proper investigation and awareness is of utmost importance as it causes significant financial constraints derived from workers health cost and from livestock production losses when the disease is confirmed. The work up is essential because infected workers might be a source of infections to other colleagues, family and the consumers.

Key words: Hepatitis; Slaughterhouse workers; Liver infections; Transaminitis;Occupational safety; Abattoir

INTRODUCTION

Slaughterhouse workers (SHW) are at a higher risk of infectious hepatitis that can be multifactorial and should be evaluated for viral, bacterial, and parasitic organisms.Viral infections are commonly sustained by certain reservoirs e.g., the hepatitis B virus(HBV) has been found in gorillas, monkeys and cattle[1,2]. Slaughter house personnel including butchers are at a higher risk of infections from cuts and blood-letting, with the possible risk of the transmission of blood-borne pathogens to their colleagues[2,3].

The objective of this review is to evaluate the common etiologies of hepatitis in SHW that will be helpful for the assessment of the patients coming with hepatitis. It causes significant financial constraints derived from workers health cost and from livestock production losses if the disease is confirmed. This is also certainly important,as, the infected workers might be a source of infections to other colleagues, family,and the consumers.

COMMON ETIOLOGIES OF HEPATITIS IN SHW

Viral infections

HBV: Several cases of HBV infection have been reported in the SHW. This not only affects their colleagues but also their families[4]. HBV can be transmitted parenterally,perinatally, sexually, and horizontally. Horizontal transmission occurs via open wounds and by saliva, which is an important concern for the SHW as studies have reported infection in the SHW via this transmission[5].

SHW is also a high-risk group for HBV infections like the surgeons and blood donors etc. Many studies have compared rates of HBV infection among the high-risk groups, including the SHW, in the hospital and community based locations and found that HBV infection was quite higher in the community than reported in the hospital cases[6]. Butchers are exposed to the public during encounters of sale; also, infection of the cattle from the SHW is a concern, which can affect the community. SHW should be considered high-risk population for HBV infection, like health care workers and be recommended HBV vaccination[3]. A recent update by American Association for the Study of Liver Diseases in regard to the high-risk who should be screened for HBV infection , identifies the slaughter house workers at risk , in view of the blood or the body fluid exposure and requires post-exposure prophylaxis[7].

Hepatitis E virus (HEV): HEV infection in humans is usually rare in developed countries but is more frequent in many developing countries[8,9]. Majority of HEV infections are unremarkable and self-limiting but can lead to acute liver failure in immunosuppressed patients[10,11].

HEV is reported in the wild boar, camels, cows and goats. In addition to the fecaloral route, consumption of contaminated water, raw or undercooked animal tissues or organs such as liver can be a source of HEV infection[12-14].

Rift Valley fever virus (RVF): RVF virus is an RNA virus responsible for causing significant illness both in humans and animals[15]. Mostly the patients are asymptomatic or have mild flu like disease, but small percentages of patients develop a life-threatening illness with ocular disease, hepatitis, encephalitis or hemorrhagic fever[16,17].

Humans are mostly affected by having contact with the blood and the fluids of the animals infected with RVF virus during slaughtering, taking care of sick animals or during the animal birth. Therefore, SHW and cattlemen are at an increased for the infection due to direct exposure to the infected animals[18,19].

Bacterial infections

Q fever: Q fever is a zoonotic disease caused by the bacterium, Coxiella burnetii. The disease was first seen in Australia among the meat packers and mentioned as“abattoir fever”[20]. The organism has extensive and worldwide reservoir, mostly ungulates, can be transmitted in the urine, feces, milk and parturition products of infected animals[21]. Humans dealing with animals are mostly infected after the inhalation of contaminated aerosols in the air[22].

The disease may present acutely with a wide range of symptoms like fever,pneumonia, hepatitis and different neurologic manifestations ranging from simple headache to meningitis, encephalitis or both. Chronic disease can manifest later, after an initial infection, as endocarditis, or chronic fatigue syndrome[21,23]. Many outbreaks have been reported in the different parts of the world. Wilson et al[24]investigated the largest outbreak of Q fever in Scotland reporting about 110 cases, which occurred in the setting of the co-located slaughterhouse. In Korea, Chu et al[25]also reported the seroconversion of about 10.2% among SHW for Q fever. In their research, the critical risk factor was the contact with cattle blood especially around the mouth. Esmaeili et al[26]found a higher seroprevalence among butchers and SHW in Iran in a large crosssectional study. The total seroprevalence of Q fever among subjects in the study was 22.5%.

Salmonellosis: Typhoid fever, a common infectious disease, typically manifests as acute systemic disease involving multiple body organs, and difficult to distinguish clinically from other infections. The liver can also be affected resulting in hepatomegaly and transaminitis. Although, acute hepatitis due to salmonellosis is a rare entity, delay in the treatment leads to increase mortality[27]. This is a very common foodborne illness and associated with contaminated poultry meat and pork[28].Multiple studies through the world have evaluated the risks factors causing the transmission of salmonella to the humans[29,30]. SHW dealing with the poultry directly are at a higher risk for getting infected.

Campylobacter jejuni:Campylobacter jejuni, a gram-negative bacterium, is responsible for causing a major food borne gastroenteritis in humans[31]. It also causes a variety of extra-intestinal manifestations including meningitis, hepatitis, gram negative bacteremia and cardiac complications[32]. The common mode of transmission to humans include eating and handling of contaminated poultry[33]. Broiler flocks are infected in the poultry houses. Many studies have discussed factors responsible for the infection of the broiler flocks[34-36].

Leptospirosis: Leptospirosis is a zoonotic disease caused by spirochetes belonging to the genus Leptospira. Different domestic animals host this bacterium and include cattle, pigs, and sheep[37]. Humans are infected through the broken skin or exposure to contaminated water and soil from infected urine of animals[38]. SHW are increasingly exposed to Leptospira species and have noted to have the higher seroprevalence values twice those of other non-risk occupations[39,40]. The identified factors leading to increasing prevalence in SHW are smoking, drinking at work, and poor hygiene at work[38,41]. Most of the infected cases are mild but more severe clinical spectrum of leptospirosis include hepatitis, and Weil’s disease with renal failure and jaundice[42].Esmaeilli et al did a serological survey of leptospirosis among different population groups in Iran. The major risk factors associated with higher prevalence included eating hare meat and exposure to dead animals[43].

Bovine tuberculosis: Although, an uncommon cause of hepatitis in slaughter workers, Mycobacterium bovis (M. Bovis) is transmitted from animals to humans, either through the ingestion of animal products or through the airborne inhalation of spores[44]. Both domestic and domesticated animals are infested by M. Bovis and include cattle, sheep, pigs, goats, cats, dogs and horses[45]. The disease spectrum is similar to that of Mycobacterium tuberculosis and includes fever, night sweats, and weight loss. The other symptoms result, depending on the tissue of the body infected by the organism[46].

Brucellosis: Brucellosis, a zoonotic bacterial illness affects both animals and humans worldwide. It spreads systemically and mainly affects the lymph nodes, liver, spleen and bone marrow. The intracellular location of the bacterium is responsible for chronic infections. It commonly infects the gastrointestinal tract, but brain, nerves,GU, skin and hepatobiliary systems are also involved[47-49]. Brucella hepatitis usually occurs in the chronic granulomatous form with mild transaminitis, but acute cases have also been reported[49-51]. Brucellosis is transmitted to humans via the intake of contaminated milk products or during physical contact with infected tissues of the animals or inhalation of contaminated aerosols[52,53]. SHW, shepherds, veterinary doctors, meat packing staff and lab staff are at an increased risk for the infection, due to increased exposure to the contaminated tissues[53].

Clostridium perfringens (C. perfringens): C. perfringens cause food poisoning from food contaminated with the organism such as eating undercooked meats. Toxin mediated illness is usually self-limited and cause abdominal pain, nausea and diarrhea and last for about 6-24 h[54]. The worst form of illness is gas gangrene. Gas gangrene with C. perfringens typically presents with necrosis of the soft tissue, gas production, and septicemia. It rarely involves internal solid viscera like liver, kidneys,heart, etc. Hepatic infection possibly results from the extension of infection into the biliary tree and then into the liver[55,56]. Immunocompromised patients, such as liver transplant patients, are at an increased risk of infection with C. perfringens[55,57]. Very few cases of C. perfringens causing allograft failure are reported in the literature[58-60].The disease has also been reported in the animals especially broiler and may be a source of transmission to the immunocompromised SHW[61].

Chlamydia psittaci: Ornithosis is a bacterial disease caused by Chlamydia psittaci and transmitted from infected parrots, pigeons, sparrows and many other bird species. The patients usually inhale the infected organism in the form of aerosolized respiratory secretions or dried feces or contact from the infected tissues of the birds[62,63]. The common symptoms of Psittacosis include influenza-like illness but can worsen to severe pneumonia and other non-respiratory health problems.Transaminitis with hepatomegaly and jaundice has been reported in the literature[62,64].

Parasitic infections

Echinococcosis: Echinococcosis is a zoonotic parasitic infection caused by larval form of different species belonging to the Echinococcus tapeworms[65]. Cystic echinococcosis represents a persistent zoonosis and one of the etiologies of parasitic hepatitis.Humans are mostly infected via ingesting parasitic eggs excreted within the feces of the definitive hosts, resulting in the development of cysts, primarily in the lungs and liver. This causes damage as they enlarge resulting in hepatitis and pneumonitis[65].Some cases are reported in France and Moldova but the disease is likely present worldwide[66,67].

The prevalence in South America ranges from 20%-95% in some areas[68]. Although intermediate hosts are variable, the common ones include sheep, goats, pigs, camels,horses, and cattle65]. Human Liver is mainly affected by the sheep strain (G1) resulting in echinococcal cysts[69].

Toxoplasma gondii: Toxoplasma gondii is a common parasitic infection with varied clinical presentations. The disease ranges from symptomless stage to a wide spectrum of clinical presentation ranging from fever and lymphadenopathy to multi-organ involvement including hepatitis, encephalomyelitis or myocarditis[70,71]. Toxoplasma gondii is commonly transmitted via drinking water or eating undercooked/raw meat contaminated with tissue cysts[72]. Many studies have reported an increased prevalence of infection in the SHW[70,73].

Trichinosis: Trichinosis is a parasitic infection transmitted commonly by ingestion of partially cooked/uncooked or raw pork contaminated with the cysts or larvae[74]. The incubation period is variable from a few days to weeks depending on the stage of the transmission (enteral phase or parenteral phase). The disease has acute and chronic phases. The earlier manifestations of trichinellosis include gastrointestinal upset with diarrhea along with, fever, muscle aches and persists while the larvae migrate throughout the body[74]. Larval tissue penetration and migration in the body is responsible for immune-mediated inflammatory reaction resulting in eosinophilia.Severe illness causes cardiac, neurological, hepatic manifestations and thromboembolic disease. Hepatic involvement is rare but has been reported in the literature[75,76].

Fungal infections

Candidiasis and other fungal infections can be transmitted to the SHW but rarely cause hepatitis in an immunocompetent patient. The possibility of hepatitis is usually in the patient with systemic candidiasis or severe sepsis due to candidiasis.

APPROACH FOR THE EVALUATION AND MANAGEMENT OF THE PATIENTS WITH HEPATITIS WORKING IN THE SLAUGHTER HOUSE

There is a wide array of the etiologies causing hepatitis in the patients working in the slaughter house (Table 1). The initial evaluation of hepatitis should guide whether it is an isolated presentation, or a manifestation of the systemic illness. The predominant hepatitis presentation is usually viral in etiology which includes HBV or HEV.Management is usually observant in acute disease, requires clinical monitoring to evaluate for possible liver failure. As per current guideline , the anti-viral medication are served for the fulminant presentation. The inquiry regarding the prevalent livestock diseases in the community can help in diagnosis. The type of the animal exposure will assist in identifying the causative organism. This is discussed in Figure 1.

The systemic manifestation should be evaluated for meningoencephalitis, renal failure, pancytopenia, pulmonary infiltrates, splenomegaly, cardiac diseases, skin and soft tissue infections, lymphadenopathy and muscular diseases. Management (antimicrobial) largely varies if the infection is bacterial or parasitic, hence the initial serology and imaging studies should guide to differentiate between the etiologies.Some bacterial diseases present as acute systemic illness and are usually from the atypical organism. Thus, empiric treatment with doxycycline may be considered while awaiting the bacterial serology. The bacterial infections, like bovine tuberculosis, will have chronic onset and will need thorough evaluation before consideration of anti-tuberculosis treatment. The parasitic etiology can be suspected based on characteristic imaging finding like the echinococcal cysts in liver or lungs.The other parasitic causes can be ruled out based on the serum serology and stool examination for the ova and parasites. Figure 2 elaborates a proposed algorithm for the assessment and management of slaughter house workers presenting with hepatitis.

CONCLUSION

This review concludes that SHW are high-risk occupational group for hepatic infections and there should be regular screening tests against the transmissible infections. All SHW should be instructed to see medical attention as soon as they there an event that might lead to transmission of disease. This is especially important for the workers directly involved in animal slaughtering. Individuals involved in transportation and handling of animal residues, or inspection the carcasses may be at a lower risk.

Table 1 Various microorganisms responsible for causing hepatitis among slaughterhouse workers along with their reservoirs, routes of transmission, diagnostic tools, clinical features treatment and preventive strategies

PCR: Polymerase chain reaction; ELISAs: Enzyme-linked immunosorbent assays; NtRTIs: Nucleotide analog reverse-transcriptase inhibitors; NRTIs:Nucleoside analog reverse-transcriptase inhibitors; MAT: Microscopic agglutination test; BCG: Bacillus Calmette-Guérin; TST: Tuberculin skin test; IGRAs;Interferon-gamma release assays; HBV: Hepatitis B virus; RVF: Rift Valley fever virus; HEV: Hepatitis E virus; C. Perfringens: Clostridium Perfringens.

Figure 1 Etiology of hepatitis in slaughter house workers based on the type of the animal exposure.

Figure 2 Algorithm for the evaluation and management of hepatitis in the patients working in Slaughterhouses.