Schistosoma

Prof Dr Kamran Ashraf

Shifa-ul-haq

Biology

Schistosomes are blood flukes and belong to the • Class Trematode• Order Digenea• Family Schistosomatidae

Family SchistosomatidaeBilharziellaOrnithobilharziaSchistosomaTrichobilharzia

Minor GenraAustrobilharziaDendrobilharziaGigantobilharziaHeterobilharziaMicrobilharziaSchistosomatium

Genus SchistosomaS mansoniS hematobiumS japonicumS intercalatumS mekongi

Currently, 21 species of this genus have been recognized

Host RangeDigeneticWide host range in case of S. japonicumS. bovisS. mattheeiS. rodhaini

Dogs, cats, rodents, pigs, horse and goats, serve as reservoirs

Intermediate HostsS. hematobium and S. intercalatum by BulinusS. mansoni by BiomphalariaS. japonicum by OncomelaniaS. mekongi by Neotricula

Right-Bulinus Left-Oncomelania

Flash Video of Life Cycle about 2.30 Seconds

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Period of communicabilityLife span 5-10 years( up to 30), so infected human

can excrete eggs up to 10 years.An infected snail can release cercariae from several

weeks to 3 months of its life.An infected snail can lay eggs 300-3000/day

Schistosomiasis

BilhaziasisSnail FeverUrinary SchistosomiasisKatayama Fever (Acute Type)Swimmer’s Itch or Orientobilharziasis (Orientobilharzia,

Trichobilharzia , Schistosoma spindale )

Theodor Bilharz 1st describe the cause of urinary Schistosoma.

In ancient Egyptian Papyri symptoms of chronic haematobium was described as a “Dripping Penis Disease”

Schistosoma eggs have been recovered from Egyptian and Chinese mummies

Distribution 2nd most prevalent parasitic disease in the world,

only behind the Malaria

More than 250 million people are infected (WHO, 2013)120 million people are symptomatic. Another 700 million people are at risk of infection.

Geographic Distribution78 countriesThe endemic areas Africa, the Caribbean

South America, East Asia, and the Middle East

200 000 mortality1.7-4.5 million DALYsDALY (Disability Adjusted Life Years)?One lost year of "healthy" life.

What, if it’s a huge problem

VaccinationThe administration of radiation-attenuated cercariaeAntigens from Schistosomules by P-I Lille, FranceSchistosoma paramyosinTarget the fecundity of the female Schistosomes

Treatment PraziquantelSomehow Artemether

At least 243 million people required treatment for Schistosomiasis in 2011 (WHO)

The number of people reported to have been treated for Schistosomiasis in 2011 was 28.1 million

ReasonsShortage of medicineHigh cost of PraziquantelNo other proven alternativePatent competition

ConcludingMore than 250 million affected700 million at riskNo vaccine possibility in near future243 million required treatment, but only 28 million

got itBut the problem not halted here

Global WarmingAn Average increase in the temperature of the

atmosphere which can contribute to changes in global climate patterns.

How Global Warming Works?

Causes of Global WarmingBurning of Fossil Fuels (coal/crude oil)

Causes of Global WarmingPopulation Increase

Causes of Global WarmingDeforestation

Causes of Global WarmingTransportation- Fuels (LPG, Kerosine, Fuel, Jet Oil)

Causes of Global WarmingIndustrial Process, manufacturing of steel, cement

Causes of Global WarmingAgriculture and FarmingMethane is 20% responsible for global warming and

2/3 of methane is produced by animalsRuminants produce 80 million metric tons of methane

annuallyMethane is more potent green house gas than co2

Interestingly Ciliate Protozoa are more responsible for methane production (Isotricha, Eudiplodinium, Epidinium + Entodinium)

Causes of Global WarmingWaste Management Landfills are also major source of methane

Causes of Global WarmingUse of Natural Gas for Cooking

Environmental and Human Effects of Global Warming

Increase in average temperature : More extreme heat waves, less cold spell of winter

Increase in frequency of extreme events: tornados, floods, heat waves, snow fall

Rising in temperature and variable precipitation: decrease production of staple food: Increase in Malnutrition

Environmental and Human Effects of Global Warming

Population Displacement:FloodingSea level risingMore than half of the world's population is now living

within 60km of the sea

Environmental and Human Effects of Global Warming

• UV Exposure• Skin Cancer• Premature Aging• Cataracts• Suppression of Immunity

Environmental and Human Effects of Global Warming

Climate-Sensitive Diseases

Development of cold-blooded animals is positively related to temperature.

Development will arrest when temp. drops below acritical threshold

Lowest developing temp. or “biological zero”The higher the temperature, the higherthe possibility that the host snail will shed cercariae

of S. japonicum

According to available temperature data for 1960 and 2000, the median January temperature, averaged across the 193 observing stations in China, increased by 0.9°C.

The mean temperature will continue to rise; indeed at an accelerated pace with predicted increases by 2030 and 2050 of 1.7 and 2.2°C, respectively

Biologic model and experiments identified a temperature threshold of 15.4°C for development of Schistosoma japonicum within Oncomelania hupensis, and a temperature of 5.8°C at which half the snail sample investigated was In hibernation

Historical data suggest that the geographic range of

O. hupensis is cold tolerant and restricted by the mean January temperature of 0°C

So, the increasing average temperatures associated with global warming are hypothesized to increase the ranges of O. hupensis habitat

At the same time, longer seasonal periods of mean temperatures > 15.4°C (the minimum temperature needed for parasite development) mean that the “accumulated degree-days” necessary for parasite development and transmission will occur in progressively more regions than before

Ultimately, as global warming progresses, more areas currently deemed as marginal for snail and schistosome habitat are expected to become recognized transmission zones