Zoonotic Parasitic Diseases in Northeast: A Public Health Concern!!
Dr Neithono Kuotsu, Dr Raghubir Singh and Dr Shyamananda Mukherjee
College of Veterinary Sciences and Animal Husbandry, Jalukie, Nagaland
The north eastern states of India, constitutes seven sisters and one brother state with a vast geographical area distributed among Assam, Nagaland, Manipur, Arunachal Pradesh, Sikkim, Mizoram, Tripura and Meghalaya. The total geographical area of 2,76,300 square kilometers (approximately) includes fifty five percent of under rich forest diversity with wild flora and fauna and forty five percent is utilized by human beings for inhabitation or cultivation purpose. The majority of populations in these states are traditionally dependent on livestock and forest produce for their livelihood. Northeast states are having distinct climate variations within short ranges due to changes in topography and conditions are conducive for the transmission of zoonotic diseases.
Any disease or infection that is naturally transmissible from vertebrate animals to humans and vice-versa is called as zoonoses. Altogether parasitic, bacterial, viral and rickettsial zoonotic diseases are estimated to cause 2.5 billon cases of human illness and 2.7 million human deaths a year. Due to northeastern states climatic condition, suboptimal sanitation infrastructure and scarce veterinary and medical services, the parasites may be prevalent more in this region. Parasitic zoonoses affects human and animal health directly and consequently affect livestock production. Factors such as poverty, lack of personal hygiene, defecating in open spaces, scarcity of potable water, abundance of stray animals, high population density and certain culinary habits are responsible for the rising prevalence of this zoonoses which includes human fasciolopsis, paragonimiasis, taeniasis; cysticercosis, echinococcosis; hydatidosis, toxoplasmosis, cryptosporidiosis, gnathostomiasis, dirofilariasis and other important helminthic diseases. Following are the Parasitic zoonoses with a public health concern in north east:
Fasciolopsiasis
Fasciolopsiais caused by Fasciolopsis buski is the largest intestinal fluke which is found in the intestines of humans and pigs. The eggs released from the intestine of human will release miracidia and finds a freshwater snail host where it undergoes different developmental stage and the released cercaria will be encysted as metacercariae on aquatic, edible plants. The prevalence of fasciolopiasis is related to consume these plants by human or pigs causes this infection. Fasciolopsiasis is endemic where pigs are raised and fed with freshwater plants in subtropical north-east hilly region.
Paragonimiasis
Paragonimiasis is a food-borne parasitic infection caused by the lung fluke, most commonly by Paragonimus. The infection occurs by eating undercooked or pickled crustaceans that may be carrying the metacercariae of Paragonimus spp. and human infection takes place by eating raw boar or pig meat because these animals serve as paratenic hosts. The first indigenous case of human paragonimiasis was described from Manipur, demonstrated ova in the sputum and identified as Paragonimus spp. Paragonimiasis cases have been detected almost every year in Manipur. Parasitological and immunological surveys revealed that paragonimiasis has been hyperendemic in parts of Arunachal Pradesh, Nagaland with more male population got infection than female and in Nagaland, half of the patients attending the TB clinic are actually suffering from pulmonary paragonimiasis by P. heterotremus. Therefore, a recommendation to give a special attention to paragonimiasis while diagnosing for TB in Assam, Arunachal Pradesh, Manipur and Nagaland.
Cysticercosis and Taeniosis
Cysticercosis is caused by Cysticerus cellulosae, the larval form of the tape worm Taenia solium. Humans acquire cysticercosis through faeco-oral contamination with Taenia solium eggs from tape worm carriers. Taeniosis is due to ingestion of undercooked pork contaminated with cysticerci or tissue cysticercosis in the subcutaneous tissue, muscle, or organs due to ingestion of viable eggs released from the worm carriers (taeniosis patients). The occurrence of C. cellulosae in the muscles of pigs is very well established in different places of north eastern states. C. bovis has also been observed in cattle and buffaloes. The human occupants having close contact with domestic animals round the year may expose to many animal borne diseases especially human cysticercosis. Cases of cysticercosis have been reported from Shillong and other states indicates that the infection rate could be high among the human populations since large numbers of people are eating pork as their main food and their method of preparation is different from usual method.
Toxoplasmosis
Toxoplasma gondii is a coccidian protozoan parasite of felids with a wide range of intermediate hosts that include all warm blooded animals including humans. Patients with HIV/AIDS are infected with opportunistic pathogen of T. gondii with central nervous system involvements. The reports of the prevalence of T. gondii from animals in Northeast India are scanty. A serological survey for T. gondii antibodies in free-ranging mithuns of Nagaland, has revealed the overall seroprevalence of anti T. gondii antibodies was 42%. Toxoplasmosis has been recognized for abortion and neonatal mortality in sheep and goats in Arunachal Pradesh indicating the zoonotic potential of the parasite in north eastern states, however, there are very few reports on the prevalence of this parasitic infection among pregnant women and infants of northeastern states. Toxoplasmosis is an occupational zoonosis also and infects more frequently the groups like veterinarians, pet keepers and farmers.
Cryptosporidiosis
This is the most common opportunistic parasite in HIV/AIDS patients and causes life threatening chronic diarrhea in immune-compromised individuals and is caused by Cryptosporidium parvum. Cryptosporidium oocysts are also detected in drinking water supplies. Its prevalence increases in rainy season and hospital based reports indicate the presence of infection in north east states.
Dirofilariasis
The natural hosts for the Dirofilaria species that cause infection in man are dogs and wild canines like foxes, wolves and raccoons. Infected mosquito occasionally infect human with the third stage larvae during a blood meal. In man, D. repens usually wanders in the subcutaneous tissue and produces a granulomatous nodule. Dirofilariasis is an emerging zoonotic disease. Cases of a subcutaneous human dirofilariasis caused by filarial worms of the genus Dirofilaria been reported in this regions of Assam. D. immitis in dogs has been reported from Mizoram, Nagaland and Assam.
Gnathostomiasis
Gnathostoma spinigerum is a parasitic nematode that causes gnathostomiasis and the clinical manifestations are called creeping eruption, larva migrans. The larval nematode is acquired by eating raw or undercooked fish and meat. Ocular involvement with G. spinigerum occurs years after the initial infection that is acquired by ingestion of poorly cooked, pickled seafood or water contaminated with third stage larvae. The zoonotic parasite is widely prevalent among the animal species in the north east regions. A number of human cases of intraocular gnathostomiasis have been reported from Assam, Meghalaya and erythematous skin lesions from Manipur.
Hydatidosis
- granulosus has a wide geographical distribution in livestock and becoming an increasing risk for human health. Hydatidosis is caused by a metacestode (larval stage) of Echinococcus species. E. granulosus distribution is higher in developing countries, especially in rural communities where there is a close contact between the dog, the definitive host, and various domestic animals, which may act as intermediate hosts. Prevalence of this parasitic infection in carcasses of yak in Arunachal Pradesh, pigs of Assam, Mithun, Cattle, Buffaloes in Nagaland and dogs of Mizoram, Assam increases the significance of it as public health importance disease in the region. However, there is no record of hydatidosis from human in the region.
Climatic change associated with global warming, increased vector populations, globalization, extensive deforestation for agricultural cultivations and human occupation, which are indirectly causes instability and movement of wild life, the large demand for livestock food products, the lack of safe drinking water, the large number of stray animals, certain cooking practices, outdoor defecation, lack of personal hygiene, and the high population density are responsible for the rising prevalence of parasitic zoonoses. In this changing scenario, food safety is of the utmost importance. There is a need for better coordination of medical and veterinary sciences along with improvement in collaborative approaches to formulate appropriate control strategies.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5436287/
