PUBLIC HEALTH THREAT CAUSED BY ZOONOTIC DISEASES IN BANGLADESH
Keywords:Zoonotic diseases, bacterial, viral, parasitic, fungal, humans, animals, birds, Bangladesh
Diseases and infections shared between animals and humans are mainly called zoonotic diseases which may be categorized as emerging, reemerging and neglected. All types of these diseases occur t hroughout the world including Bangladesh. The results on the prevalence and effects of zoonotic diseases in humans and animals of Bangladesh are analyzed from the published literatures and presented in this report. It appears from the literature that there are about 1415 human pathogens of which 61% are zoonotic and nearly half of all human pathogens can be classified as emerging, of which 75% of these are caused by zoonotic pathogens. The major zoonotic bacterial diseases recorded in Bangladesh are Anthrax, Tuberculosis, Brucellosis, Salmonellosis, Campylobacteriosis and Leptospirosis, of which only Anthrax has been reported as clinical outbreaks form in both the humans and cattle. During the period 2009 to 2012, anthrax caused death of hundreds of cattle and more than 650 cases of cutaneous anthrax in humans including fatalities in two humans associated with anthrax. The major reported viral zoonotic diseases in Bangladesh include Avian influenza, Rabies, Nipah virus infection, Japanese encephalitis, Rotavirus and Dengue fever. Avian influenza caused by highly pathogenic H5N1 in humans and poultry in Bangladesh and about six humans affected with H5N1 but all of them have recovered. Since 27 March 2007 when Avian influenza was reported to have occurred for the first time in Bangladesh, this virus spread in 51 out of 64 districts with more than 480 outbreaks, culled more than two million poultry birds and cost Tk. 55 billion (US $ 757.9 million) in Bangladesh. Rabies is considered as a priority zoonosis in Bangladesh and it is mainly transmitted to humans and food animals mainly through dog bite nearly 100,000 people and at least 2000 died of rabies in 2009 in Bangladesh. Nipah virus infection is an important emerging infectious disease has been recognized since 2001 in Bangladesh and up to February 2011, 173 humans cases have been identified, of which 110 (63.58%) died. Japanese encephalitis (JE) is a vector borne zoonotic disease, first recognized in Bangladesh since an outbreak in 1977 and 12.38% encephalitis patients had JE virus infection which was associated with mortality, physical disability and cognitive difficulties. Rotavirus is a worldwide distributed zoonotic disease affecting mammals and birds and it has been reported from Bangladesh in humans (23.75%), animals (12 to 43.78%) and broiler birds (13.15%) associated with diarrheic syndrome. Dengue fever was first reported in Bangladesh in 1964 and outbreak that began in 2000 predominantly caused by DENV-3 in which 5551 cases recovered and 93 Dengue related deaths were reported. The dermatomycosis has been reported in 9.3% cattle, 18.6% goats and 25.2% in contact humans. The major zoonotic parasites recorded in cats in Bangladesh include Paragonimus westermani (9.09%), Ancyclostoma tubaeforme (36.36%), Dirofilaria immitis (9.09%), Toxocara cati (45.45%) and Toxoplasma gondii (9.09%), in dogs include Diphyllobothrium latum (13.3%), Diphylidium caninum (16.69%), Echinococcus granulosus (9.17%), Ancylostomum caninum (9-100%), Gnathostoma spingerum (40.0%), Toxocara canis (23.3%), Trichuris vulpis (13.8%) and in pigs include Entaemebea histolytica (17.24%) and Balantidium coli (60.34%). The prevalence of zoonotic protozoan diseases recorded in humans in Bangladesh include amebiasis (E. histolytica 4.71% & E. dispar 12.6%), giardiasis (21% in children & 51% in malnourished children), cryptosporidiasis (1.4 to 3.5% in diarrheic patients) and visceral leishmaniasis (kala-azar) which was first reported in Jassore in 1824 but still sporadic outbreaks are occurring in the different districts in Bangladesh. Sero-surveillance studies showed 16 to 17% cattle, 17.65 to 53.6% sheep, 12.09 to 35.4% goats and 15.89% women had T. gondii antibodies in Bangladesh. It appears from these results that all types of emerging, reemerging and neglected zoonotic diseases are widely prevalent and pose a great threat to human health in Bangladesh. Neglected Veterinary medical profession and its extension services, poor people without any knowledge of zoonotic diseases who are in close contact with livestock and their products, and unhygienic processing, maintaining and marketing the livestock and livestock products have made the situation graver in Bangladesh.