Malaria (Protozoan)

Brief History

• Malaria is one of the longest surviving threats to humans.

• Records of the disease go back 4,000 years.

• The actual word malaria has its roots in the miasma theory

• In Italian the words “Mal” and “aria” means bad air- miasma

• In the history there has been many attempts of curing malaria these are:

  • A chinese herbal remedy called Qing-hao used to treat fever episodes. The active ingredient called artemisinin are still used today is a very potent and effective antimalarial drug.

  • During the middle ages treatments for malaria included bloodletting limb amputation and trepanning.

  • Some people used nets oversleeping areas to avoid potential risks.

  • In 1737 a French explorer found that the bark of the Cinchona tree could be used to treat malaria and in 1820 in French researcher isolated quinine, the active ingredient from the cinchona tree.

  • In 1934 the first synthetic drugs used to prevent malaria was developed by the Italian scientist Hans Andersag

  • In 1939, Swiss scientist Paul Hermann Müller used DDT (Dichlorodiphenyltrichloroethane) to kill the Anopheles mosquito Victor. However the mosquitoes develop resistance.

Transmission

• Malaria is mainly transmitted through a vector. Thus it is a vector-borne disease.

• The female Anopheles mosquito transmit malaria.

• Infected transfusion of blood

• Contaminated needles or syringes

• Transmission from an infected secondary host (human) to a mosquito that is having a blood meal.

Symptoms

• Fever

• Sweats

• Chills

• Headaches

• Malaise

• Muscles aches

• Nausea

• Vomiting

EXTREME SYMPTOMS

• Swelling in the brain

• Kidney failure

• To clearly identify if an individual is affected by the disease they must be blood tested

• Symptoms may be in cycles

• Symptoms may rise as early as 7 days after infection and as late as a year after

• Possible symptoms occurring periodically for years.

Stages of the infection

1. A primary host which is a mosquito bites and an infected secondary host which in this case is a human

2. SPOROZOITE multiplies asexually in liver and red blood cells

3. There plasmodium produces thousands of sexual gametes in blood called MEROZOITES

4. Merozoites infect the red blood cells to reproduce more

5. The red blood cell (erythrocyte) raptures- beginning symptoms

6. Some blood cells do not rapture instead they form gametocytes-female and male

7. The bite from a mosquito transfers gametes to a mosquito where fertilisation occurs

8. New asexual generation forms in mosquito salivary glands

9. 

Treatment and vaccines

• Malaria can be cured with prescription drugs. Such as:

  • Artemisinin-based combination therapy medicines like artemether-lumefantrine (most effective)

  • Quinine and Chloroquine for P. vivax parasite (only in places where it is still sensitive to this medicine)

  • Primaquine should added to the main treatment to prevent relapses of infection with the P. vivax and P. ovale parasites

• A vaccines used to prevent malaria- fSPZ Vaccine

Prevention and control

• There are 12 insecticides belonging to one of four classes currently used in the control of the female anopheles mosquito (malaria vector):

  • organochlorines

  • organophosphates

  • carbamates

  • pyrethroids.

• Avoid traveling countries or regions where there has been an outbreak of the case

• Use sleeping nets

• Use mosquito repellents

Adaptation of plasmodium species

• Through the several life stages of the plasmodium different antigen molecules are produced preventing the host from launching an effective immune response

• In different parts of the world the mosquito vector of malaria has become resistant to the insecticides used to kill it.

• The rapid generation turnover of mos pathogens and insect resistance has led to widespread pesticide resistance.

• The plasmodium hides in the red blood cells protecting themselves from immune responses

• While in the red blood cells the plasmodium produces adhesion proteins thus changing the shape of the red blood cell. This change interferes with the movement of the cell through the capillaries. Consequently, facilitating the reproduction and survival of the parasite in the cell.

• Before human immune system responds the plasmodium parasites alter the adhesion proteins again.

• The plasmodium parasites Kill liver cells causing a gap between the healthy and dead cells. The parasites then use this gaps to infect other liver cells

• The parasite accumulate calcium ions from the liver cells. They use this to block the presentation of antigens on the surface of the cell, thus avoiding the human immune system

• The plasmodium has evolved to exit the infected mosquito through it’s salivary gland, once the anticoagulant protein has been injected into the host-the human.

Facts

• The viruses that cause malaria are RNA viruses

• Malaria is a protozoan

• Malaria is caused by 4 protozoan parasitic species

  • Plasmodium falciparum (deadliest)

  • Plasmodium vivax

  • Plasmodium ovale

  • Plasmodium malariae

• The 4 protozoan parasitic species belong to the plasmodium genus

• All of malaria species are unicellular eukaryotic organism that cannot survive outside of their host

• 500k deaths occur annually from malaria. Most of these deaths are young children and pregnant women in sub-saharan Africa.

Ebola (Virus)

Brief History

• Ebola was first appeared in 1976

• Two simultaneous outbreaks were observed, these were in the countries:

  • South Sudan

  • Congo

Transmission

• The virus was initially transmitted to a human from an infected fruit bat- Animal-to-person contact

• After the introduction into the human population the virus spread through a direct human-to-human contact

Facts

• Fruit bats are the natural host of the ebola virus

• Ebola virus disease aka EVD is a severe, often fatal disease in humans,

• The average fatality rate of ebola is from 50%- depending on circumstances.

• The virus persists for more than 9 after recovery

• There are 5 species within the ebola genus

  • Ebola virus

  • Sudan ebolavirus

  • Taï Forest ebolavirus

  • Bundibugyo ebolavirus

  • Zaire ebolavirus

Symptoms

Initial symptoms

• Fever

• Fatigue

• Muscle pain

• Headache

• Sore throat

Severe symptoms

• Vomiting

• Diarrhoea

• rash

• Impaired kidney and liver function

• Internal and external bleeding

Stages of the infection

1. Incubation period: 2 to 21 days

2. Ebola virus initially infects the dendritic cells of the immune system (this prevents an immune response against the virus)

3. The virus replicates on Mars and infect the cells of multiple organs causing cell death

4. The cell death leads to the release of cytokines

5. This cytokines initiate an immune response

6. The volume of cytokines released result in the thinning of blood vessel walls causing them to leak blood

7. Blood pressure drops, body temperature drops, ultimately causing the sufferer to go into shock and die

Treatment and vaccines

• There is no cure or treatment for the Ebola virus

• Individuals suffering from the virus are supported with oral and intravenous fluids combined with the treatment of specific symptoms

Prevention and control

• Avoid animal to human transmission by cooking meat thoroughly

• Human to human transmission by wearing personal protective equipment insure a good person hygiene and refrain from unprotected sex

• Surveillance of hotspots

• Contact tracing

• Safe burials, mobilisation and quarantine

Fire Blight (Bacteria)

Cause

• Pathogens causing blight are typically bacterium

• It is a highly infectious disease caused by the bacterium Erwinia amylovora

Transmission

• blossoms where the bacteria is transported by bees during pollination

• surface injuries caused by insect feeding, hail or mechanical damage

• bacterial exudate can be dispersed locally by wind, rain, insects and birds

Symptoms

• trees appear to have been ‘scorched’ by ‘fire’ (Figure 1)

• brown wilting of blossoms, shoots and leaves, with a scorched appearance (Figure 2)

• leaves remain attached to stems (Figure 2)

• shoots and branches bent into a 'shepherd's crook' shape (Figures 3 and 4)

• bacterial ooze in warm, humid weather (Figures 5 and 6)

• discoloured sunken areas or cankers on branches, limbs and trunks (Figure 7)

• red-brown discolouration of the sapwood

Control and Prevention

• Fire blight is successfully excluded from australia due to its strict biosecurity- quarantine

  • Australia has enforced a strict pest and disease surveillance at its borders to avoid exotic plants and pests cause major human, environmental and economic impacts.

  • DAFF (Department of Agriculture and Water Resources) has enforced inspection and import treatment requirements in place to reduce the risk of harmful pests and diseases getting into and establishing in Australia

• There's no single effective treatment for fire blight.

Facts

• Australia's agriculture generates a lot of money. Thus contributing to the nation’s GDP by 2.4%. For example, Australia’s pome fruit industry itself generates 475 million per year.