United States virus

Introduction

There are over 2,000 species of fleas, and the most common domestic species? That’s right, the cat flea! The cat flea, Ctenocephalides felis, serves an important niche and bridges the gap between life and death of the ten unfortunate patients of United States virus (USAV). However, there are many genetic and behavioral factors of the species that go into making this flea a prime vector of USAV, such as its biology/anatomy, habitat preferences, feeding habits, and mating habits. Even though the studied patients of USAV pertained to the United States, C. felis occupies an extremely broad geographic region extending far beyond the boundaries of the United States nearly covering the entire world!

 

Geographic Range

The cat flea is one of the few species that is truly “cosmopolitan” and found almost everywhere in the world, including North America, South America, Europe, Asia, and even Australia (Hubbard). Aside from the name, C. felis isn’t restricted to cat hosts alone, but feeds on a wide variety of felines, canines and rodents as well. Even though C. felis is the most common domestic flea, what makes it the most common species and how is it distributed so broadly around the world? The answer is that the cat flea feeds on a wide variety of abundant animals found in nearly every continent in the world. Some examples of these include dogs, coyotes, red foxes, grey foxes, bobcats, panthers, skunks, raccoons, opossums, ferrets, and several species of rodents (Mazurek). Therefore, since canines, felines, and rodents are found on almost everywhere in abundance, the fleas are found on the same continents in abundance as well. In fact, the cat flea is so common around the world that in some countries it is even the most common canine flea! So clearly, these fleas are very abundant and can be found all over the world. However, the only limiting factor to its spread is the “inability for it to survive at temperatures below -1 °C for more than five days at any stage of its life cycle” (Rust and Dryden 1997). The flea’s inability to survive extremely low temperatures explains why they don't thrive in the Antarctic and freezing temperate regions around the world. Temperature not only prevents the flea from complete global distribution, but also determines the approximate concentration of the population in an area. For example, optimum conditions for the development and living conditions of C.felis are 20-30 °C with a humidity of 70% or over is required, which can limit the location of where it can be in a specific area (Rust and Dryden 1997). In conclusion, these fleas occupy almost every continent in the world, but environmental factors and temperature ranges effect the population concentration as well as the population distribution in that specific area.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Vector Biology

 C. felis goes through a complete metamorphosis during its life time. As pictured above, it has 6 stages: the egg, the first, second, and third stage larvae, the pupae, and the adult. The larvae hatch within a few days of being laid as eggs. They are without eyes, legs, and they feed mostly on the feces of adult fleas. When this feces isn’t available, they eat any organic matter that they can find. They “prefer to develop in areas protected from rainfall, irrigation, and sunlight…”(Zentko). The larval stage lasts for five to fifteen days. After the larval stage they become a pupae that collects dirt and debris to camouflage it. Adult fleas detect carbon dioxide in the air, and this tells them when to emerge. Adult fleas are wingless, reddish brown, and are laterally compressed. They have leg muscles equipped with a spring type set up, this allows them to run and jump long distances. On average, the adults live for twenty-five days. The flea lives in the same area as the host when not feeding, and on the animal while feeding. Adult C. felis fleas have a genal comb with 5 or more horizontal pointed spines. The head is twice the length of the height, and spine one is close to the same length as spine two in the genal comb. They have three pairs of walking legs along with one pair of thoracic legs. The appendages are projecting from the body in plain sight.

 

Habitat

The cat flea can live in almost any habitat. This has allowed it to colonize most inhabited various places on earth. “The only limiting factor to its spread is the inability for it to survive at temperatures below -1 degree C for more than five days at any stage of its life cycle” (Mazurek). C. felis is a very common flea, it is found infesting cats in most places. It is also found infesting dogs, foxes, wild cats, and other animals that live in close proximity. Cat flea larvae also require high humidity and a mild temperature in order to develop properly. These fleas try to spend as much time on the host feeding as they can. They can be transmitted from host to host if an animal is in close proximity to the infested animal.

 

Feeding Habits

C. felis, like all fleas, feed on blood from the host it is infesting. And also like most fleas, the cat flea lives on its host that it is feeding on. The morphological adaptations play a huge role on the feeding habits, for an adult female cat flea can “average up to 13 micro liters of blood meal per day which is over 13 times her body size!” (Rust and Dryden 1997) With that being said, females fleas generally feed much more often and take in more blood meal than males due to the constant nutritional demand of egg laying. C. felis larvae feed on fecal/organic matter from the adult fleas on the host while adults feed on blood meal from the host directly. The cat flea prefers felines, canines and rodents.

 

Mating Habits

Mating can occur with C. felis in two location types: host that is indoors and host that is outdoors. With indoor conditions, mating occurs year round. Mating ale However, outdoor conditions have to be optimal for mating to occur, it is preferred that it is around 70% in humidity and warmer weather. Therefore outdoor mating usually occurs in the spring and summer seasons. Indoor mating/egg laying is the most efficient because the female is able to lay up to 35-40 eggs per day, which adds up to a total of 2,000 eggs in the female’s lifetime (Milne 1980).

 

Conclusion

C. felis  has been known to transmit various diseases ranging from plague to infestations such as tape worms. It is very good at surviving, and is very hard to get rid of. It has a wide range of hosts, and a wide range of habitats. This flea has been found in the homes of all of the patients, because of its versatility in both habitat and disease transfer; it is the most likely vector.

 

 

References Cited

Hubbard, C. 1968. Fleas of Western North America. New York: Hafner Publishing.

Mazurek, M., and J. Dorshorst. 2016. Ctenocephalides Felis- The Cat Flea. http://bioweb.uwlax.edu/bio210/s2012/dorshors_jaco/index.htm

Milne, M., and Milne, L. 1980. The Audubon Society Field Guide to North American Insects and Spiders, Alfred A. Knopf, Inc. New York, NY, USA.

Mullen, G. R., and L. A. Durden. 2009. Medical and Veterinary Entomology. Second ed. Cambridge: Academic.

Rust, M.K., and M.W. Dryden. 1997. The Biology, Ecology, and Management of the Cat Flea.  Animal Review of Entomology 42:451-473

Saeed, S. 2014. Ctenocephalides Felis (blokha). http://animaldiversity.org/accounts/Ctenocephalides_felis/

Zentko, D., and D. Richman. 2014. Cat Flea- Ctenocephalides Felis (Bouche). http://entnemdept.ufl.edu/creatures/urban/occas/catflea.htm