ANTI-PARASITIC VACCINES FOR CANINES AND FELINES
Dr. Rashmi mishra1 and Dr. Pashupathi M2
1Division of Veterinary Parasitology, Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh.
2Division of Biochemistry, Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh.
Parasitic diseases cause huge economic loss in production and infertility. During the past 5 years, the incidence of GI nematode infections in India have reached 25% -78%. The main parasite control strategies include anti-parasitic drugs and vaccination. Due to emerging drug resistance and food safety issue, the use of anti-parasitic drugs is limited. Vaccination strategy is economical, no recurrent expenses, frequency of administration is less, solid immunity, no drug resistance, environment free of chemical residues, maintaining biodiversity. Veterinary vaccines constitute around 23% of the global annual heath market share and the anti-parasitic vaccines have less contribution among all.
One of the common illness in young puppies is Giardiasis. It is spread by faecal-contamination of water, food, and soil. Canine and feline giardiasis is characterized by watery diarrhea, excess foul-smelling gas, vomiting, decrease in appetite, decreased energy, and frequent urges to poop. Humans can also catch infection from their pets. To prevent giardiasis, vaccine is available with name GiardiaVax for dogs, which is launched in the United States around late 90s. It is a killed protozoa vaccine marketed by Zoetis (Mexico). This vaccine significantly reduces the incidence and severity of disease along with the duration of cyst shedding. Dose of vaccine is 1ml by subcutaneous route. A second dose has to be given 2-4 weeks after the 1st vaccination and repeated annually. For cats also giardia vaccine is available in the name – Giardia Fel-O.
Canine babesiosis is one of the tick-borne infection caused by protozoal parasite Babesia canis. Dogs of all age groups are affected but young puppies are more susceptible which leads to 1-12% mortality. Canine babesiosis is marked by clinical signs like fever, coffee colored urine, weakness, pale mucous membranes, dull, swollen lymph-nodes, haemolytic anaemia, splenomegaly and thrombocytopenia. Babesia divergens and Babesia microti are the zoonotic species, which can be transmitted to humans. Two vaccines have been developed against canine babesiosis till today. The first vaccine – Pirodog, contains soluble parasite antigens (SPA) from B. canis, while the recently released NobivacPiro include SPA from the B. canis and B. rossi with an intention to increase the strain specific immunity. Pirodog is a subunit vaccine launched by Fort Dodge in Spain, which provides protection for 6 months against canine babesiosis. Two injections have to be administered to 5-month-old puppy 3-4 weeks apart, and then boosters are given annually or biannually. It is marketed by Merial/ RhoneMerieux (France) company. NobivacPiro is also a subunit vaccine, which provides 80 % protection for 6 months and marketed by Intervet International company.
Hookworms specifically Ancylostoma caninum, Uncinaria stenocephala and Ancylostoma brasiliense are among the most common parasitic infections in canines. This parasite is transmitted through skin penetration and faecal-contaminated water, food, and soil. Infection is characterized by black-tarry stools, vomiting, decreased appetite, weight loss, anemia, lethargy, weakness and pale gums. Skin infections, coughing and pneumonia may also be noticed, but are less common. Hookworms in dogs are zoonotic parasite and causes cutaneous larval migrans / creeping eruption in humans. Vaccine against canine hookworms was launched in US in 1973 as Canine hookworm vaccine. It was the first commercially launched helminths vaccine, which is given to pups at the age of 3–4 months by subcutaneous route. It is a gamma-irradiated A. caninum L3 larva vaccine marketed under Jensen-Salsbery Laboratories, however this vaccine was discontinued since 1975.
Canine leishmaniosis is a considerable global zoonotic parasite, potentially fatal to both humans and dogs. It is transmitted biologically by sand flies. Leishmaniosis is very common in dogs younger than three years and older than eight years. Boxer, Cocker Spaniel, Rottweiler and German Shepherd breeds of dogs are more susceptible to infection. Leishmaniosis is identified by generalized lymph adenomegaly, loss of body weight, decreased or increased appetite, lethargy, pale mucous membranes, splenomegaly, polyuria or polydipsia, fever, vomiting, diarrhoea. Cutaneous and ocular form are also very common including non-pruritic exfoliative dermatitis with or without alopecia, nodular/popular/pustular dermatitis, blepharitis and keratoconjunctivitis. Vaccine against Leishmania donovani was launched in Brazil in 2006 as Leishmune®. It is the first canine parasitic subunit vaccine. It comprises of 3 doses at 21-day interval given subcutaneously, with 76-80% efficacy. It is marketed under Pfizer company but, now withdrawn from the market. Another recombinant subunit canine vaccine named Leish-Tec against Leishmania donovani is marketed by Hertape Calier company. Two more subunit vaccine named CaniLeish and LeishTecis against Leishmania infantum and Leishmania chagasi respectively are available in market against canine leishmaniosis, which are marketed by Virbac (Europe) and Hertape Calier (Brazil).
Feline toxoplasmosis is one among the most prevalent feline parasitic diseases, caused by Toxoplasma gondii. Usually, the cats infected with T. gondii shows no clinical signs however symptoms like fever, lethargy, loss of appetite, pneumonia, jaundice, ocular and nervous lesions are common in immune-suppressed cats. This parasite is transmitted by – food, water or soil which is contaminated with the infected cat faeces, eating of raw or under-cooked meat of infected animals and by trans-uterine route. Vaccine against feline toxoplasmosis is available as T-263, which is an attenuated tissue cyst-based vaccine that significantly reduces oocyst shedding in cats.
Although chemical anti-parasitic treatments are the cornerstone of parasite control strategies, but due to emergence of drug resistance, frequent re-infections following chemotherapy and concerns about food safety has pushed researchers to explore for more environmentally friendly alternatives, with vaccines coming in first on their list of priorities. Even though there are some antiparasitic vaccines available, still there is huge requirement for its development. We need effective and economic vaccine for animal care.
References :
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- Rodriguez-Morales, A.J. ed., 2017. Current Topics inGiardiasis. BoD–Books on Demand.
- Stutzer, C., Richards, S.A., Ferreira, M., Baron, S. and Maritz-Olivier, C., 2018. Metazoan parasite vaccines: present status and future prospects. Frontiers in cellular and infection microbiology, 8, p.67.
