Schistosoma haematobium

Last updated:

Geographic Range

Schistosoma haematobium can be found in Africa and the Middle East and southern Europe. Schistosoma haematobium can be found in areas where their intermediate hosts such as Bulinus spp. and Physopsis spp. reside. (Roberts and Janovy, 2000)

Habitat

Schistosoma haematobium reside in tropical climates and near rivers near the coast. Studies show Schistosoma haematobium prefer to inhabit forest zone areas towards the south. Savanna zones towards the north do not include heavy populations of S. haematobium, although they inhabit areas in North Africa and the Middle East. Evidence suggests that snail infection rates of S. haematobium miracidia increase from July to November and at normal water levels. (N'Goran, et al., 1997; Roberts and Janovy, 2000)

  • Aquatic Biomes
  • rivers and streams

Physical Description

Adult males are around 10 mm and females are 15 mm in length. Both sexes of S. haematobium have a strong oral sucker and a smaller posterior ventral sucker. Males have a gynecophoral canal where females are usually located. Research shows the gynecophoral canal transfers nutrients and hormones from the male to the female and vise versa. Males have five to nine testes and no cirrus pouch, cirrus or prostate cells. The genital pore is located directly behind the ventral sucker. Females have only one ovary near the center of the body and a uterus that can contain 20-100 eggs. (Agnew, et al., 1988; Basch, 1991)

Development

Schistosoma haematobium has a very complex life cycle that is different from most other digenean life cycles. Schistosoma haematobium is distinct from many trematodes in that the sexes are separate in this species. Both male and females must remain together for long periods of time in order for the males to fertilize the females. This process can be difficult while the worms are inside the host's body since the males have to find the females in order to copulate.

According to experimental tests Schistosoma haematobium eggs increase their hatching time upon the dilution of urine in water. Eggs found to hatch 5 minutes after dilution of the urine continue to do so after 10-15 min. Hatching time increases under light and with vibration or disturbance of the eggs. Eggs then hatch into miracidia(larval stage) that have ciliated epithelia and swim in water. After finding the snail intermediate host, (Bulinus spp.) miracidia penetrate the snail and shed their epithelia. Miracidia without epithelial tissue are called sporocysts. Next, the sporocysts produced daughter sporocysts. The sporocyst grows by absorbing the host tissue, then the germinal cells divide and produce embryos that grow into daughter sporocysts. According to most digenean life cycles, most species will now produce rediae. Although most digenean sporocysts asexually produce a second immature from termed a redia Schistosoma haematobium neglects this stage and no rediae are formed.

Next, the sporocyst asexually produces the next immature form termed cercariae with tails that leave the snail host in order to find a definitive host. The cercariae burrow into the skin and lose their tails causing a condition called "Swimmer's Itch." Studies show that at temperatures under 10°C and over 40°C, cercariae do not develop properly and demonstrate a significant increase in their mortality. Preferable conditions for penetration of the skin would be between these extremes. Inside the host, the cercariae shed their tails and migrate to the liver via the host's circulatory system. The cercariae will feed on blood in the vessels until they reach their adult form. From the liver S. haematobium travels to the bladder (venus plexus) where they begin to produce eggs. Egg formation occurs about 9.5 weeks after infestation. (Agnew, et al., 1988; Ghandour, 1976; Matsunaga, et al., 1987; Roberts and Janovy, 2000)

Reproduction

Schistosoma haematobium has a very complex life cycle that is different from most other digenean life cycles. Schistosoma haematobium is distinct from many trematodes in that the sexes are separate in this species. Both male and females must remain together for long periods of time in order for the males to fertilize the females. This process can be difficult while the worms are inside the host's body since the males have to find the females in order to copulate. The sporocyst asexually produces the next immature form termed cercariae. From the liver of the definitive host, S. haematobium travels to the bladder (venus plexus) where they begin to produce eggs. Egg formation occurs about 9.5 weeks after infestation. (Agnew, et al., 1988; Ghandour, 1976; Matsunaga, et al., 1987; Roberts and Janovy, 2000)

  • Key Reproductive Features
  • simultaneous hermaphrodite
  • sexual
  • asexual
  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning

Behavior

Human infection occurs when the definitive host comes into contact with water containing cercariae released from snails infected with S. haematobium. The cercariae then burrow into the skin, spread, grow, and reproduce. Over the next few days the eggs are passed through the urine of the host. Traveling from the intermediate host to the definitive host is a complicated process. By separating the sexes the species must ensure that both male and female cercariae reach the host in order to reproduce, thus risking the chances of survival. (Basch, 1991)

Communication and Perception

Bristles and small spines probably act as tactile receptors, and these animals also may have reduced chemoreceptors. (Brusca and Bruca, 2003)

Food Habits

Adult Schistosoma haematobium feeds on blood located in the veins around the urinary bladder of their mammalian host. (Basch, 1991)

  • Animal Foods
  • blood
  • body fluids

Predation

These animals are probably not preyed on directly but are ingested. Egg and larval mortality are high since the parasites often do not reach appropriate hosts.

Ecosystem Roles

The life cycle of this trematode includes infecting snails, particularly in the genus Bulinus and humans.

Species Used as Host

Economic Importance for Humans: Positive

NONE

Economic Importance for Humans: Negative

Schistosoma haematobium is the cause of schistosomiasis also known as Bilharzia. Hosts of the parasite are humans. Schistosomiasis affects 200 million people worldwide and is considered one the most serious pathogenic infections today.

Schistosoma haematobium is pathogenic to humans and causes blood in the and urine and sometimes in the stool. Persons affected by S. haematobium may also develop cough, fever, skin inflammation, and tenderness of the liver because the spined eggs attach to vital organs and cause tissue degeneration. Later stages of the disease may be characterized by the swelling and damaging of the bladder, liver, and other organs. The eggs of Schistosoma haematobium can clog the bladder neck and cause infection. Many researchers have also observed damage on other body structures. Chronic schistosomiasis raises the incidence of bladder cancer in many Middle Eastern countries.

Drugs are available to cure Schistomiasis although the treatment process is long and unpleasant. Praziquantel is the leading drug in America In other nations, including Africa, Trichlorfon is administered. Unfortunately once the bladder wall is infested with eggs and feeding Schistosomes, prognosis is poor and the chances of surviving are slim. (Liese, 1986; Roberts and Janovy, 2000)

Conservation Status

Schistosoma haematobium is not an ecologically endangered species. It is found abundantly throughout its normal habitats.

Other Comments

Schistosoma haematobium is a medically important parasite since bladder damage can lead to death. Calcified eggs embedded in the bladder wall increase the chances of blockage of the vessels. Although other species of Schistosoma also cause medical problems, Schistosoma haematobium is the only species that affects the human urinary system.

(Basch 1991)

Contributors

Renee Sherman Mulcrone (editor).

Janki Trivedi (author), University of Michigan-Ann Arbor, Teresa Friedrich (editor), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

asexual

reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

chemical

uses smells or other chemicals to communicate

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

motile

having the capacity to move from one place to another.

parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

References

Agnew, A., S. Lucas, M. Doenhoff. 1988. The host-parasite relationship of Schistosoma haematobium in CBA mice. London School of Hygiene and Tropical Medicine, 3: 403-424.

Anwar, M. 1962. Ciba Foundation Symposium Bilharziasis. Boston: Little Brown Company.

Basch, P. 1991. Schistosomes. New York: Oxford University Press.

Brusca, R., G. Bruca. 2003. Invertebrates. Sunderland, Massachusetts: Sinauer Associates, Inc..

Ghandour, A. 1976. A study of the relationship between temperature and the infectivity of Schistosoma mansoni and Schistosoma haematobium cercariae. Journal of Helminthology, 50: 193-6.

Liese, B. 1986. The Organization of Schistosomiasis Control Programmes. Parasitology Today, 2: 339-340.

Matsunaga, K., H. Nojima, D. Koech. 1987. Dependence of hatching of Schistosoma haematobium miracidia on physical and biological factors.. Parasitology Research, 74: 55-60.

N'Goran, E., P. Bremond, E. Sellin, B. Sellin, A. Theron. 1997. Intraspecific diversity of Schistosoma haematobium in west Africa: chronobiology of cercarial emergence. Acta Trop, 66: 35-44.

Roberts, L., J. Janovy. 2000. Foundations of Parasitology, Sixth Edition. Boston: McGraw Hill Companies Inc..