Download - Schistosoma and Global Warming
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