Thursday, January 24, 2008

MMIC PBL Package 2

Pathogens that cause infections during jungle training

Viruses

Organism:
Hepatitis A virus (picornavirus)

Mode of transmission:
Fecal-oral route,
direct contact with an HAV-infected person, ingestion of contaminated food or water prepared by a HAV-infected person
Disease(s) caused:
Hepatitis A
Signs & symptoms:
Jaundice, fever, anorexia, nausea, vomiting, diarrhea, myalgia, malaise, dark-coloured urine or light-coloured feces, abdominal tenderness, hepatomegaly or spleomegaly
Prevention:
Hepatitis A vaccination, short-term protection from immunoglobulin (can be given before and within 2 weeks of coming in contact with HAV), good personal hygiene and proper sanitation

Organism:
Hepatitis B virus

Mode of transmission:
Blood contact from a HBV-infected individual, unsafe injection
Disease(s) caused:
Hepatitis B
Signs & symptoms:
Yellowing of skin and eyes (jaundice), extreme fatigue, abdominal pain, loss of appetite, nausea, vomiting, joint pain
Prevention:
Hepatitis B vaccination, avoid sharing needles, syringes with HBV-infected indivduals, avoid sharing personal care items that might have blood on it, such as razors, toothbrushes

Organism:
Hepatitis E virus

Mode of transmission:
Ingestion of contaminated food or water, contact with HEV-contaminated blood
Disease(s) caused:
Hepatitis E
Signs & symptoms:
Jaundice, fatigue, abdominal pain, loss of appetite, nausea, vomiting, dark urine (tea coloured)
Prevention:
Avoid drinking water of unknown purity, uncooked shellfish, and uncooked fruits or vegetables that are not peeled or prepared hygienically

Organism:
Rabies (Mononegavirales species)
Mode of transmission:
Via bites and virus-containing saliva of an infected host (dogs, cats, foxes, insectivorous and vampire bats etc.), contaminated mucous membrane such as eyes, nose, mouth, aerosols
Disease(s) caused:
Rabies
Signs & symptoms:

Non-specific flu-like symptoms: malaise, fever, headache, discomfort at site of infection, anxiety, hallucination, insomnia
Prevention:
Anti-rabies vaccination, wash wound thoroughly with soap and water, detergent or plain water, followed by the application of ethanol, tincture or aqueous solution of iodine

Organism:
Influenza virus (type A strain)

Mode of transmission:
Farm-to-farm by the movement of live-infected birds, movement of people (especially with contaminated shoes and clothes), contact with contaminated vehicles, equipments and cages, contact with bird feces, swimming in rivers where carcasses of dead infected birds are discarded
Disease(s) caused:
Avian flu
Signs & symptoms:

Initial symptoms: high fever, usually with a temperature higher than 38˚C and influenza-like symptoms, watery diarrhoea, vomiting, abdominal pain, chest pain and bleeding from the nose and gums can be seen during the early stages
Later stage: lower respiratory tract problem: difficulty in breathing, respiratory distress, a hoarse voice and a crackling sound when inhaling, sputum production is variable and sometimes bloody

Prevention:
Avoid direct or close contact with infected poultry or surfaces contaminated with secretion and excretion from infected birds, wash hands with soap and warm water for at least 20 seconds before and after handlilng raw poultry and eggs, ensure poultry food products are well-cooked

Organism:
Nipah virus
Mode of transmission:
Close contact with contaminated tissue or body fluids from infected animals (eg. pigs)
Disease(s) caused:
Nipah virus disease and encephalitis
Signs & symptoms:

Mild or asymptomatic: high fever and muscle pains, prolong infection may result in inflammation of the brain (encephalitis) with drowsiness, disorientation, convulsion and coma
Prevention:
Avoid close contact with infected animals, always have good hygiene practice

Organism:
Chikungunya virus (CHIKV) (genus – Alphavirus, family - Togaviridae)

Mode of transmission:
The bite of an infected Aedes
mosquito (most commonly Aedes aegypti, less commonly Aedes albopictus
Disease(s) caused:
Chikungunya fever
Signs & symptoms:

Fever (can reach up to 39°C), headache, fatigue, nausea, vomiting, muscle pain, rash, and joint pain insomnia. However Silent CHIKV infections (infections without illness) do occur.
Prevention:
No vaccine for chikungunya fever is available. Precautionary measures includes the prevention of mosquito bites by wearing long sleeves and pants and/or using an EPA-registered insect repellent such as those with DEET, picaridin or oil of lemon eucalyptus on exposed skin.

Organism:
Dengue virus (consists of four closely related virus serotypes [DEN-1, DEN-2, DEN-3, and DEN-4] of the genus Flavivirus)
Mode of transmission:
The bite of an infected
Aedes
mosquito (most commonly Aedes aegypti, less commonly Aedes albopictus])
Disease(s) caused:

Dengue fever (DF) or dengue hemorrhagic fever (DHF)

Signs & symptoms:
Fever (ranging from a
mild to an incapacitating high fever), severe headache, pain behind the eyes, rashes and muscle pain and joint pain. DHF (fever, abdominal pain, vomiting, bleeding) is a potentially lethal complication.
Prevention:
No specific antiviral medicines or vaccination for dengue is available due to the many virus serotypes present. Precautionary measures includes the prevention of mosquito bites by wearing long sleeves and pants and/or using an EPA-registered insect repellent such as those with DEET, picaridin or oil of lemon eucalyptus on exposed skin.

Organism:
Japanese encephalitis (JE) virus (a Flavivirus antigenically related to St. Louis encephalitis virus
Mode of transmission:
The bite of infected
rice field breeding mosquitoes (primarily the Culex tritaeniorhynchus group)
Disease(s) caused:
Japanese encephalitis
Signs & symptoms:
Acute encephalitis (inflammation of the brain), fever, headache malaise neck rigidity, cachexia (loss of weight, muscle atrophy, fatigue, weakness and significant loss of appetite), hemiparesis (partial paralysis of one side of the body), convulsions and a raised body temperature between 38 and 41 degrees Celsius can progress to paralysis, seizures, coma and death.
Prevention:
An inactivated Japanese encephalitis(JE) vaccine is available. The vaccine is reactogenic, however the rates of serious allergic reactions (generalized urticaria or angioedema) are low. Precautionary measures includes the prevention of mosquito bites by wearing long sleeves and pants and/or using an EPA-registered insect repellent such as those with DEET, picaridin or oil of lemon eucalyptus on exposed skin.

Organism:
Yellow fever virus (a Flavivirus)

Mode of transmission:
The bite of an
infected mosquito (Transmission from human to human is mostly mediated by the Aedes aegypti mosquito)
Disease(s) caused:
Yellow fever
Signs & symptoms:

Initial phase which includes symptoms of fever and chills, severe headache, back pain, general muscle aches, nausea, fatigue, and weakness can be followed by followed by a short period of symptom remission.
Afterwards the toxic phase develops as the fever returns, with clinical symptoms including high fever, headache, back pain, nausea, vomiting, abdominal pain, and fatigue.
Hepatic coagulopathy may also occur causing hemorrhagic symptoms, including hematemesis (black vomit), epistaxis (nose bleed), gum bleeding, and petechial and purpuric hemorrhages (bruising). Deepening jaundice (the symptom which led to the name of the condition) and proteinuria frequently occur in severe cases.

Prevention:
Yellow fever vaccine, which is a live virus vaccine, is available. The vaccine generally has few side effects causing mild headache, muscle pain, or other minor symptoms in fewer than 20% of patients. Persons allergic to eggs should not be vaccinated as the vaccine is prepared in eggs and immunosuppressed individuals should not be vaccinated due to the nature of the live virus vaccine. Precautionary measures includes the prevention of mosquito bites by wearing long sleeves and pants and/or using an EPA-registered insect repellent such as those with DEET, picaridin or oil of lemon eucalyptus on exposed skin.

Extra Precautions:

  • There is an increased risk of mosquito-borne diseases during and immediately after the rainy season thus take extra precaution during this period.
  • Infected individuals should be protected from further mosquito exposure (staying indoors and/or under a mosquito net during the first few days of illness) so that they can't contribute to the transmission cycle.
* Done by: Azhar & Yvonne

Fungi

Fungi are often present in the environment such as in the soil and in decaying vegetation with the exception of Candida albicans, which is part of normal human flora. As the army is training in the jungle where they are constantly exposed to the fungi present in the environment, there is a high risk of them getting fungal infections.

Organism:
Trichophyton mentagrophytes
(dermatophytes)
Epidemiology:

World wide

Mode of transmission:

Direct contact with skin lesions of infected people, mice and rodents or with infected keratin debris on the ground

Disease(s):

Athlete’s foot (tinea pedis)

Signs & symptoms:

Itching and burning feet, skin frequently peels

Prevention:
Wear breathable shoes, wear cotton socks and change after sweating, ensure that shoes are dry before tying the shoe lace, always keep the feet dry and use talcum powder if required

Picture is taken from http://www.lib.uiowa.edu/hardin/md/cdc/4803.html

Organism:
Sporothrix schenckii
Epidemiology:

Temperate and tropical regions
Mode of transmission:

Spores present in rose thorns, sphagnum moss, soil and decaying vegetation enter the skin through exposed wounds
Disease(s):

Sporotrichosis
Signs & symptoms:

Small painless bump or lesion at the site of wound, the colour ranges from red to purple. The lesion will then grow larger and discoloured, eventually developing into an ulcer when left untreated
Prevention:
Wear gloves and long sleeves, avoid skin contact with sphagnum moss and soil especially when there is a wound

Picture is taken from http://www.healthinplainenglish.com/health/infectious_diseases/sporotrichosis/

Organism:
Cryptococcus neoformans
Epidemiology:

World wide
Mode of transmission:
Inhalation of airborne yeast cells, commonly found in soil with pigeon droppings. It can also be found in unwashed raw fruits.
Disease(s):
Cryptococcosis
Signs & symptoms:
Asymptomatic in healthy individuals
Prevention:

Immunocompromised individuals should avoid areas contaminated with pigeon or other bird droppings, such as barns and areas under bridges where pigeons roost

Picture is taken from http://www.medscape.com/viewarticle/410174

Organism:
Candida albicans
Epidemiology:

World wide
Mode of transmission:

Present as normal flora on skin, mucous membranes and GI tract
Disease(s):

Thrush, mucosal and systemic candidiasis
Signs & symptoms:

Depends on the type of disease
Prevention:
Reduce predisposing factors (eg. severe trauma, burns), oral thrush can be prevented by using clotrimazole troches or nyastin

Picture is taken from http://www.tonguethrush.com/
An example of tongue trush.

Organism:
Conidiobolus coronatus
(zygomycetes)
Epidemiology:

World-wide but mainly in tropical areas such as Indonesia, Southeast Asia and Africa

Mode of transmission:

Contact with soil and decaying vegetation or introduction of spores into nasal mucosa that has a trauma (eg. caused by an insect bite)

Disease(s):

Subcutaneous zygomycosis (chronic inflammatory or granulomatous infection restricted to the nasal mucosa)

Signs & symptoms:

Fever, lethargy, headache

Organism:
Aspergillus fumigatus
Epidemiology:

Temperate regions

Mode of transmission:

Inhalation of airborne spores from soil and plant debris

Disease(s):

All forms of non-invasive and invasive aspergillosis

Signs & symptoms:

Non-invasive (fever, malaise, coughing out blood), invasive (chills, headache, increased production of sputum which may be bloody, chest pain)

Picture is taken from http://medimages.healthopedia.com/large/aspergillosis.jpg

Prevention:

- Wear clean, dry, loose-fitting clothes whenever possible

- Avoid sleeping in wet clothes

- Keep short hair

* Done by: Ming Boon & Michelle

Protozoa

Organism:
Plasmodium
species (P. falciparum, P. vivax)
Epidemiology:
World-wide
Mode of transmission:

From infected female Anopheles mosquitoes to human

Disease(s):

Malaria

Signs & symptoms:
Fever, chills, intravascular hemolysis & cerebral malaria (P. falciparum infections)
Prevention:

Vector control using DDT, organochlorine and organophosphate mosquito control insecticides, anti-malarial drugs

Organism:
Entamoeba histolytica
Epidemiology:

World-wide with a higher prevalence in tropical countries

Mode of transmission:

Ingestion of cysts transmitted by fecal-oral route in contaminated food and water, person-to-person, animal-to-human (pigs & monkeys)

Disease(s):

Amebiasis

Signs & symptoms:
Dysentery (bloody, mucous containing stools, lower abdominal pain, tenesmus), liver abscess (right upper quadrant pain, weight loss, fever, tender and enlarged liver)
Prevention:

There are no effective immunizations and prophylaxis and thus only preventive measures are limited to personal hygiene

Organism:
Giardia
species (G. lamblia & G. duodenalis)
Epidemiology:
World-wide
Mode of transmission:

Ingestion of cysts transmitted by fecal-oral route in contaminated food and water, person-to-person

Disease(s):

Giardiasis

Signs & symptoms:

Foul-smelling, loose and greasy stools

Prevention:

Drink boiled, filtered and iodine-treated water

Organism:
Toxoplasma gondii
Epidemiology:
World-wide
Mode of transmission:

Ingestion of undercooked meat, food and water contaminated with cat feces (fecal-oral route)

Disease(s):

Toxoplasmosis

Signs & symptoms:
Often asymptomatic, immunocompetent individuals may have lymphadenopathy, fever, headaches and muscle aches
Prevention:

Avoid contact with cat feces, cook food and boil water thoroughly

Organism:
Cryptosporidium parvum
Epidemiology:
World Wide
Mode of transmission:
Ingestion of contaminated food or water and exposure to feces (Water and food borne, zoonotic)
Disease(s):
Cryptosporidiosis
Signs & Symptoms:
Diarrhea, nausea, vomiting, fever, weight loss, dehydration
Prevention:
Good hygiene practices, drink boiled water, avoid exposed feces, uncooked food

Organism:
Cyclospora cayetanensis
Epidemiology
:
World Wide

Mode of transmission
:
Ingestion of contaminated food or water and exposure to feces (Water and food borne, zoonotic)

Disease(s):

Cyclosporiasis

Signs & Symptoms:

Diarrhea, stomach bloatness, nausea, loss of appetite, low grade fever

Prevention:
Good hygiene practices, drink boiled water, avoid exposed feces, uncooked food

Organism:
Balantidium coli
Epidemiology
:
Tropics

Mode of transmission:

Ingestion of food or water
contaminated by human or animal feces containing B. coli cysts. (Water and food borne, zoonotic)
Disease(s):

Balantidiasis

Symptoms:

Dysentery, abdominal pain, colitis

Prevention:
Purification of water, proper food handling, careful with feces disposal

Organisms:
Enterocytozoon bieneusi, Septata intestinalis
Epidemiology
:
World wide

Mode of transmission
:
Water and food borne, zoonotic

Disease(s):

Microsporidia

Signs & Symptoms
:
Conjunctivitis, keratoconjunctivitis, bronchiolitis, pneumonia, rhinosinusitis, disseminated infection

Prevention:

Purification of water, proper food handling

Organism:
Trypanosoma cruzi
Epidemiology
:
Latin America
and tropical rainforest
Mode of transmission:

Insert borne (
triatomine bugs) and food borne
Disease(s):

Chagas’ disease

Signs & Symptoms:

Acute:
fever, fatigue, body aches, headache, rash, loss of appetite, diarrhea, and vomiting, mild enlargement of the liver or spleen, swollen glands, and local swelling
Prevention and Precaution:

Spraying infested dwellings, wearing protective clothing, and applying insect repellent to exposed skin and bed net

* Done by: Kau Hin, Ming Boon

Bacteria

Organism:
Leptospira interrogans
Epidermiology:

World wide especially in tropical areas and most particularly Southeast Asia

Mode of transmission:

Contact (mucous membrane exposure) or ingestion of urine of infected animals (rodents, wild mammals & domestic animals) contaminated food

Disease(s):

Leptospirosis

Signs & symptoms:
Biphasic, early (fever, chills, intense headache & conjunctival suffusion), second (aseptic meningitis, jaundice & renal failure)
Prevention:
Difficult because the organism is not eradicated from wild animals which constantly infect domestic animals. Use of doxycycline, practice good personal hygiene, avoid swimming in streams where risk of infection is high, avoid drinking of water from stream

Helminths

Organism:
Schistosoma japonicum
(flatworm)
Mode of transmission:

Penetration through the skin when contact with infected snails

Disease(s):

Schistosomiasis, affecting the GI tract

Signs & symptoms:

Itching, dermatitis, fever, chills, diarrhea, lymphadenopathy and hepatosplenomegaly

Prevention:

Avoid swimming in affected areas, eliminating snail host when possible, proper disposal of human waste

Organism:
Wuchereria bancrofti
, Brugia malayi
Mode of transmission:
Bite of female
Anopheles and Aedes mosquito

Disease(s):

Filariasis
Signs & symptoms:

Elephantiasis (massive edema), coughing & wheezing at night, fever
Prevention:

Use of proper clothing, mosquito netting and repellent

* Done by: Shahirah

References:
1. http://www.healthinplainenglish.com>health>infectious diseases>sporotrichosis

2. http://www.treatnailfungus.org>treatment>athlete's foot fungus

3. http://www.emedicine.com>name of disease
4.
http://mosqpro.com>mosquito borne diseases
5. http://www.mycology.adelaide.edu.au>mycoses 6. http://gsbs.utmb.edu>micro book>chapter 79 7. http://www.cdc.gov>virus name 8. http://www.who.int>dengue 9. Levinson W. 2006. Review of Medical Microbiology and Immunology, 9th edition. McGraw Hill Companies

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