Wednesday, January 23, 2008

 

MMIC dPBL 2 overview of case













Image: http://www.yahoo.com/ > Image> Indonesia

Indonesia [1] , in southeastern Asia, has a strategic location along major sea-lanes that connect the Indian and Pacific Oceans. The majority of the Indonesia’s islands consist of rugged volcanic mountains covered by dense tropical forests; however, some of the islands have swamps and plains. Indonesia is one of the most volcanically active regions on earth, with more than 100 active volcanoes. The region is subject to frequent earthquakes. The climate is tropical with an average daily temperature range of 21.1°C to 32.2° C with 80 to 90 percent humidity in the lowlands. Temperatures and humidity are lower as elevation increases, and temperatures below freezing can occur at elevations over 9,800 feet. Indonesia’s wet season occurs from November to March, and annual rainfall averages 40-78 inches.

Routes of transmission and entry of microorganism into host
Due to the humid and warm climate which is experienced in Indonesia all year round, bacterial, viral, protozoal and fungi infection can occur frequently in military soldiers.
Some pathogens are transmitted into huamns from wild animals and birds in the jungle. In the case of fungi infections, the infectious spores are carried from the soil to humans by air-borne routes. Food-borne diseases due contaminated water and food, un-cook food can also cause infections in these personnel. In addition, respiratory diseases and vector-borne diseases can also cause illness in these soldiers. Dirty living conditions such as not changing soiled clothes, not cleaning and airing of the feet frequently can also lead to microorganism infections. Other possible routes of transmission include aniaml bites (in the case of rabies), animal excretion, contaminated medications or fomites. [2]


References:
1) indonesia/">http://www.wikipedia.com>Indonesia
2) Jensen M. M. and Wright D. N. (1993) Introduction to Micobiology for Health Sciences. Prentices-Hall Inc., new Jersey

Bacteria

Presence of bacteria is extremely high in unhygienic conditions. Individuals infected by bacteria will present symptoms that may be infectious to other uninfected individual thus spreading the infection. [1] The soldiers having their army stint in Indonesia are exposed to numerous bacteria e.g. Shigella species, Salmonella species, E. coli, Campylobacter species as hygiene conditions are often overlooked. In addition, they are exposed to more bacteria during their jungle warfare training as soil, streams, rivers, animal feces, uncooked food which contain abundant amounts of bacteria. [1]

Food borne bacteria
In the jungle, military personnel have to prepare food themselves, thus the chances of consuming un-cook or contaminated food is relatively high. Therefore, they are at risk of be infected with various bacteria that are found on food when not cooked or cleaned properly. [5, 6]

Result from undercooking of food especially meat, organisms that are common include:
Campylobacter jejuni
Salmonella spp
Shigella spp
Listeria monocytogenes
Clostridium perfringens
Clostridium botulinium

Symptoms include:
Nausea
Vomitting
Abdominal cramping
Diarrhea
Fever

Shigella [3]

Transmission: Most individuals are infected with shigellae when they ingest food or water contaminated with human fecal material. Spread is always from a human source.

Causes: Shigellosis

Signs and symptoms: Fever, abdominal cramping, diarrhea, dehydration, tenesmus (straining of stool)

Salmonella species [2]

Transmission: Salmonella is spread from the carcasses to humans when the poultry is eaten undercooked. Other sources of Salmonellae include milk products, food, and water contaminated with animal feces or urine.

Causes: Salmonellosis, enteritis, Typhoid fever, primary septicemia

Signs and symptoms: Nausea, vomiting, abdominal pain, diarrhea, fever, weight loss, anemia, anorexia, headache.

Campylobacter [1]

Transmission: Campylobacter is usually acquired from food (especially poultry), milk, or contact with infected animals (e.g. dogs) through the fecal-oral route.

Causes: Acute enteritis

Signs and symptoms: Bloody diarrhea, fever, abdominal pain, headache.


Animal vector bacteria [1,3]
As the soldiers are training in the jungle, they will encounter many different forms of wildlife. Bacteria carried by them may be transmitted to the soldiers. Common ones include:

Brucella spp (contact with infected animals e.g. dogs, pigs, cattle, horse)
Francisella sp. (contact with wild animals that carry ticks, mites and lice)
Yersinia spp (contact with rodents that carry fleas that carry the bacteria)
Pasteurella multocida (cat and dog bites)

Soil vector bacteria [2, 3]
In addition to the exposure to various fauna and flora living in the jungle, soldiers may also come in contact with soil. Soil is a place where many bacteria flourished thus they chances of getting an infection casued by a soil organism is also relatively possible


Clostrodium tetani [2]

Transmission: Soils or materials in contact with animal wastes are usually heavily contaminated with C. tetani and offer excellent sources of infections. Soil-contaminated wounds are most frequent source of infection.

Causes: Tetanus

Signs and symptoms: Spasmodic contractions (tetany) in involved muscles that are affected by the toxin and muscle spasms.

Mode of control: Vaccines

References

1. Levinson, W. (2006). Review of Medical Microbiology & Immunology. San Francisco, California: Lange Medical Books/McGraw-Hill publishing company

2. Elliott T., Hasting M. and Desselberger U. (1997). Lecture Notes on Medical Microbiology. Blackwell Science, Oxford

3. Walker, T.S. (1998). Microbiology. Philadelphia, Pennsylvannia: W.B Saunders Company

4. http://aggie-horticulture.tamu.edu/ > Search > food poisoning

5. http://www.medicinenet.com/ > Search > food poisoning



Done by: Star team


 

Virus

Virus is a sub-microscopic infectious agent requires a host to outside cell. [1] Each viral particle, or virion, consists of genetic material, DNA or RNA, within a protective protein coat called a capsid. [1] The capsid shape varies from simple helical and icosahedral (polyhedral or near-spherical) forms, to more complex structures with tails or an envelope.

When a virus infect a host cell, several changes occurs. [1] For example,
- death of cell due to inhibition of macromolecule synthesis
- fusion of cells to form multinucleated cells
- malignant transformation
- no morphological/functional changes

Pathogenesis in the infected patient involves [1]
- transmission of virus and its entry into host
- replication of virus (viral proteins) and damage to cells (lysis)
- immune responses against virus
- persistence of virus (unable to be remove from the body even after immune responses has been mount)

Virus can be transmitted from person-person or animal-person. [2] Person-person transmission can be due to exposure to respiratory secretion, saliva, blood (transfusion, sharing of needles), semen, fecal contamination of water or food. [1] This is called horizontal transmission. Person-person transmission can also be from maternal to fetal/child across the placenta or during breast-feeding. This is called vertical transmission. Animal-human transmission occurs directly when infected animal is exposed to human while indirect transmission occurs through the bite of an insect vector e.g. mosquito. [1]

Viral infections in human and animal hosts usually result in an immune response and disease.[5] Viruses are usually eliminated by immune responses in the body. Antibiotics have no effect on viruses, but antiviral drugs have been developed to treat life-threatening infections. Vaccines that produce lifelong immunity can prevent virus infections e.g. poliomyelitis.
Here are some of the viruses that have have shortlisted


Parainfluenza virus [2, 4]
Epidemiology: Parainfluenza 1, 2, 3 & 4, with Parainfluenza 1& 2 being commonly during autumn and Parainfluenza 3 infections occur throughout the year.

Transmission: Inhalation of large respiratory droplets, person-person contact. Re-infection occurs throughout life as body’s immunity to it is short.

Signs and symptoms: cold-like syndrome, croup, cough, chest pain

Causes: bronchiolitis, bronchitis, upper respiratory tract infections and pneumonia.

Modes of control: No vaccine is yet available for routine use







http://www.yahoo.com/ > Image > Parainfluenza virus




Influenza A virus [2, 4, 8]
Influenza A virus infects multiple species. Wild aquatic birds are the nature host to a variety of influenza A viruses. The virus is then transmitted to other species and causing devastating outbreaks in domestic poultry or give rise to human influenza infections. There are several types of influenza A virus:

· H1N1 caused "Spanish Flu."
· H2N2 caused "Asian Flu."
· H3N2 caused "Hong Kong Flu."
· H5N1 is a pandemic threat in 2007–8 flu season; Avian Flu
· H7N7 has unusual zoonotic potential.
· H1N2 is endemic in humans and pigs.
· H9N2, H7N2, H7N3, H10N7


Avian Flu [2, 4, 8, 9]
Epidemiology: Bird populations especially in Southeast Asia

Transmission: Avian Flu caused by H5N1 virus infects bird populations. The infected birds then spread its infection through saliva, nasal secretion, blood and droppings to other animals and humans with extensive physical contact e.g. direct contact with these bodily fluids or through contact with surfaces contaminated with them

Causes: Avian Flu

Signs and symptoms: Fever, cough, sore throat, pneumonia, breathing difficulties and sometimes diarrhea.

Modes of control: H5N1 Vaccines but they are not always effective due to continuous mutation of the virus, culling of infected bird population, protection used when dealing with droppings.







http://www.yahoo.com/ > Image > Avian Flu Virus



Influenzavirus B [2, 4, 8]
Epidemiology: Worldwide occurrence: epidemics are local and pandemics are worldwide

Transmission: Spread by inhalation of small aerosol droplets expelled for infected individual, saliva, blood, feces, nasal secretion.

Causes: Pneumonia, lower respiratory infection, acute influenza infection in adults and complications influenza virus infections.

Signs and symptoms: Fever, sore throat, muscle aches, coughing, nausea, vomiting

Modes of control: amanatdine, rimantadine etc, killed vacinne contains predicted yearly strains of
influenza A & B virus



SARS coronavirus [6, 8]
Epidemiology: Most number of SARS cases occurred in People’s Republic of China, Hong Kong, Taiwan, Singapore and Canada with 7%, 17%, 14% & 17% fatality respectively

Transmission: Spread mainly by close person-to-person contact. When an infected person coughs or sneezes, droplets of mucus or saliva that contain the virus are sent through the air. Once these droplets land on the mouth, enter the nose or eyes, an infection can occur. However, the airborne spread of SARS does not seem to be a major route of transmission. In addition, kissing, touching, sharing utensils for eating and drinking, or talking with an infected person are also a risk factor for infections. The presence of virus in the stool also suggests the possibility of oral-fecal transmission

Causes: Severe acute respiratory syndrome (SARS)

Signs and symptoms: Fever, Chills, muscle soreness, headache and a general feeling of discomfort also are common. Severe pneumonia, leading to an insufficient amount of oxygen in the blood (hypoxemia) can also occur
Modes of control: Wash your hands frequently with soap and hot water, Cover your mouth and nose when sneezing and coughing. Use soap and hot water to wash the utensils, towels, bedding and clothing of someone with SARS. Don't use these items yourself until they're clean.







http://www.yahoo.com/ > Image> SARS coronavirus



Alphavirus [2, 4, 5]














Chikungunya Virus (It is a virus under the category of alphavirus)
Epidemiology: The disease was first recognized in Eastern Africa in the 1950s. Outbreaks were also reported in Malaysia, India, Sri Lanka and Indonesia in 2006. In 2008, 6 infections caused by chikungunya virus were reported in Singapore.

Transmission: Chikungunya is spread by the bite of an infected mosquito. The main vector is mosquito Aedes aegypti. Other mosquito likes Aedes albopictus and Culex can also transmit the disease. Mosquito becomes infected when they feed on a person infected with chikungunya. Monkeys and other wild animals may also serve as a reservoir of the virus. Infected with mosquito can then spread the virus to other humans when they bite. There is no direct person to person spread.

Causes: Chikungunya fever

Signs and symptoms: Chills, fever, headache, vomiting, fatigue, nausea, rash and muscle and joint pain, some patients may also develop a rash affecting the trunk

Modes of control: The most effective means of prevention are those that protect against any contact with the disease-carrying mosquitos. These include the usage of insect repellents with substances like DEET (Diethyl-3-methylbenzamide), icaridin (also known as picaridin and KBR3023), PMD (p-menthane-3, 8-diol, a substance derived from the lemon eucalyptus tree), or IR3535. Wearing bite-proof long sleeves and trousers also offers protection. In addition, garments can be treated with pyrethroids, a class of insecticides that often has repellent properties. Vaporized pyrethroids (for example in mosquito coils) also have a certain special repellency.
Of all the alphavirus, Chikungunya virus is the only virus in this category that is distributed in South East Asia (Indonesia), thus it is the most probably virus from this category to infect soldiers who are training in the forest of Indonesia








http://www.yahoo.com/ > Image > Chikungunya Virus




Flavivirus [2, 4, 5]













Epidemiology: Aedes mosquito, which carries dengue and yellow fever, is found in urban areas, pools of water and jungles while Culex mosquito is found in the forest, urban areas. Disease is more common in summer.

Transmission:









Signs and symptoms: Flu like symptoms (chills, fever, rash, aches), dengue yellow fever

Mode of control: Mosquito breeding sites should be eliminated. Live attenutaed vaccines are available for yellow fever virus


Adenovirus [2, 4, 10]
Epidemiology: Worldwide endemic, frequent observations in transplant patients and military recruits.

Transmission: Adenovirus can be human-to-human transmission mainly by fecal-oral or respiratory route, by fingers, by fomites (including towels and medical instruments). In addition, close interaction among people such as military barracks promotes the spread of the virus

Causes: Adenoviral pneumonia, due to adenovirus serotype 4 & 7, is a complication of acute respiratory diseases in military recruits, conjuctivitis

Signs and symptoms: Fever, cough, pharynitis
Modes of control: Live vaccine for serotype 4 and 7 are avaliable for military use






http://www.yahoo.com/ > Image > Adenovirus


Enterovirus [2, 3, 5]
Polioviruses (causes poliomyelitis)
Coxsackieviruses (A and B) (causes hand-foot-mouth disease)
Echoviruses
Enteroviruses
e.g.
Enterovirus 70

Epidemiology: Worldwide distribution except for poliovirus which has been eradicated, only a few random cases occurs.
Polioviruses – humans, ape, monkeys
Coxsackieviruses – human, most common in summer and autumn
Echoviruses – human
Enteroviruses - human

Infections most common in early childhood but adults get infected when their bodies do not possess the immunity against the enterovirus invading.

Transmission:
Transmitted by oral-fecal route, poor hygiene, inhalation of aerosol, ingestion via contaminated food and water, contact with infected hands and fomites, poor sanitation, crowded living conditions

Causes:
Polioviruses - poliomyelitis
Coxsackieviruses (A and B), Echoviruses and Enteroviruses - causes hand-foot-mouth disease, herpangina,aseptic meningitis, myocarditis and can cause serious disease especially in infants and the immunocompressed.
Enterovirus 71 causes respiratory infection.

Signs and symptoms: Rash disease, respiratory diseases, undiferentiated fever

Modes of control: Practice good hygiene, improve living condition

Poliovirus is an extinct disease due to vaccination except in undeveloped countries, in addition, it is manifested since young, the army soldiers are unlikely to be infected by it.


Molluscum contagiosum [1, 3, 4]
Epidemiology: Worldwide distribution.

Transmission: Transmitted by direct contact with infected human e.g. sexual contact, wrestling, or sharing of fomites e.g. towel, bed, clothing.

Signs and symptoms: skin lesion most commonly on trunk, genitalia and proximal extremities.

Causes: DNA poxvirus Molluscum contagiosum virus. There are 4 types of MCV, MCV-1 to -4, with MCV-1 being the most prevalent and MCV-2 usually seen in adults.

Modes of control: Hygiene - no sharing of baths and articles of clothing (towels), no scratching of lesion, bandage bumps.






http://www.yahoo.com/ > Imgae > Molluscum contagiosum



Bunyaviridae [2, 4]














Epidemiology: Common during summer. Found in South America, Southeast Asia, southeastern Europe and Africa.

Transmission: Transmitted by infected mosqutio, or ticks to vertebrates. The animal then becomes the resvoirs for the virus which in turn infect human. Also, humans get infected when they enter the environment of insect vector.

Signs and symptoms: Febrile illness and rash, headache, vomitting

Causes: Hantavirus pulmonary syndrome, Hemorrhagic fever

Mode of control: Elimination of vector or vector’s habitat






http://www.yahoo.com/ > Image>Bunyavirus







http://www.wikipedia.com/ > Hantavirus > Image




Hepatitis [2, 4, 5, 11]















Hepatitis A and E [2, 4, 5, 11]
Epidemiology: Worldwide, most common in tropical and subtropical regions.

Transmission: Fecal-oral route, direct contact with contaminants e.g. uncooked food, water, contact with infected individual e.g. sharing of food, drinks.

Signs and symptoms: Fever, loss of appetite, nausea, headache, pain in abdomen

Causes: Hepatitis A, Hepatitis E

Mode of control: Vaccination, good hygiene, consume thoroughly cooked food and water.

Considering that the soldiers are not exposed to blood products or any transfusion process, Hepatitis B, C and D are not possible. The lack of clean food and water in the jungle could have caused Hepatitis A and/or E infection is the soldiers.










http://www.yahoo.com/ > Image> hepatitis C





Rabies [2, 12]
Epidemiology: Animal reservoir e.g. foxes, bats, racoons. Most commonly found in Asia, Africa and South America.

Transmission: Spread from animals especially wild animals to human, Inhalation of aerosolized virus, saliva bite by a rabid animal.

Signs and symptoms: Fever, malasie, itching at the site of the bite, fear of water (hydrophobia).

Causes: infection to central nervous system (especially brain)

Modes of control: Avoid contact with wild animals as they are not vaccinated, immediate washing of wound with soap, detergent or other substances which inactivate the virus, Instill anitrabies serum with the adminstration of huamn rabies immunoglobulin (HRIG)








http://www.yahoo.com/ > Image > Rabies virus


Rhinovirus [2, 3, 4]
Epidemiology: occurs worldwide with high prevalence during winter

Transmission: crowding and close contact favors transmission via respiratory route.

Causes: chronic bronchitis, sinusitis

Sign and symptoms: coryza (inflammation of nasal membrane), fever (however not common in adults)

There is likelihood for soldiers to be infected with rhinovirus as it is transmitted by crowding and close contact, all these are common occurrence in the barrack.








http://www.yahoo.com/ > Image > rhinovirus



Human Immunodeficiency Virus (HIV) [2, 5]
Epidemiology: occurs worldwide

Transmission: Sexual contact, blood, maternal to fetal, breast milk.

Causes: HIV, other opportunistic infections as HIV-infected individual are immunocompromised

Sign and symptoms: flu-like symptoms after 2 weeks of manifestation

Assuming the soldiers visited the neighboring villages and had sexual contact/blood contact with an infected individual, there is a high chance that they are infected with HIV. However, if the soldiers had not venture out of their barrack and the jungle, the likelihood of them infected with HIV is very low as an HIV-infected individual would have been detected during their military health screening.






http://www.yahoo.com/ > Image > aids HIV virus



Norovirus [2, 4, 5]
Epidemiology: Worldwide, all ages

Transmission: faecally contaminated food or water, person-to-person transmission

Causes: stomach flu, gastroenteritis

Sign and symptoms: nausea, vomiting, diarrhea, weakness, fever.

Virus can be transmitted when contaminated food and water has been consumed, the likelihood increases when food/water is not thoroughly cooked. In army, due to large amount of food required to prepare and the lack of fire source during jungle warfare, food/water may not be thoroughly cooked.







http://www.yahoo.com/ > Image> Norovirus

Astrovirus [2, 3, 5]
The genus "Astrovirus" within the familiy of Astroviridae is divided into eight human species:
- human astrovirus 1 (HAstV-1) - human astrovirus 2 (HAstV-2) - human astrovirus 3 (HAstV-3) - human astrovirus 4 (HAstV-4) - human astrovirus 5 (HAstV-5) - human astrovirus 6 (HAstV-6) - human astrovirus 7 (HAstV-7) - human astrovirus 8 (HAstV-8)

Epidemiology: All ages especially the young and elderly. Adults in military barracks are most likely to develop the disease due to poor hygiene control.Worldwide endemic, common in tropical with rainy season

Transmission: contaminated food and water

Causes: gastroenteritis

Sign and symptoms: Diarrhea, vomiting, pain in stomach, dehydration

Virus can be transmitted when contaminated food and water has been consumed, the likelihood increases when food/water is not thoroughly cooked. In army, due to large amount of food required to prepare and the lack of fire source during jungle warfare, food/water may not be thoroughly cooked.


Filovirus [2]
There are two genera: the Ebola virus and Marburg virus. These viruses cause viral hemorrhagic fevers, characterized by bleeding and coagulation abnormalities, often leading to death. Natural reservoir of both the Marburg virus and the Ebola virus appears to be zoonotic. Infected individual symptoms may be mistaken for influenza, malaria, typhoid fever.


Marburg Virus [2]
Epidemiology: Africa, commonly transmitted by bats especially fruit bats

Transmission: disease is spread through bodily fluids, including blood, excrement, saliva, and vomit

Causes: Marburg haemorrhagic fever.

Sign and symptoms: Early stage: fever, headache and myalgia maculopapular rash present on the trunk. Later-stage: is acute and causes jaundice, pancreatitis, weight loss, delirium and neuropsychiatric symptoms, haemorrhaging, hypovolemic shock and multi-organ dysfunction, with liver failure.


Ebola Virus [2]
Epidemiology: Africa, commonly transmitted by animals e.g. monkeys, bats especially fruit bats

Transmission: airborne, from infected animals to human, human to human transmission is rare.

Causes: Ebola haemorrhagic fever.

Sign and symptoms: Early stage: high fever, severe headache, muscle, joint, or abdominal pain, severe weakness and exhaustion, sore throat, nausea, and dizziness. Later-stage: diarrhea, dark or bloody feces, vomiting blood, red eyes due to distention and hemorrhage of sclerotic arterioles, petechia, maculopapular rash, and purpura.

During jungle warfare, the soldiers are exposed to wide variety of wild animals e.g. monkey and bats. The animals may be infected with the virus and transmit it to the soldiers thus infecting them. Therefore, the occurrence of filovirus infection is rather high.


References

1. Levinson, W. (2006). Review of Medical Microbiology & Immunology. San Francisco, California: Lange Medical Books/McGraw-Hill publishing company
2. Murray, P.R. (2002). Medical Microbiology. St. Louis, Missouri: Mosby Inc.
3. Elliott T., Hasting M. and Desselberger U. (1997). Lecture Notes on Medical Microbiology. Blackwell Science,Oxford
4. Walker, T.S. (1998). Microbiology. Philadelphia, Pennsylvannia: W.B Saunders Company
5. Brook G. F., Butel J. S. and Morse S. A. (1998). Jawetz, Melnick & Adelberg’s Medical Microbiology. Prentice Hall International Inc., United States of America
6. http://www.mayoclinic.com/ > search> SARS
7. http://www.sarsreference.com/
8. http://www.wikipedia.org/ > search influenza
9. http://www.wikipedia.org/ > search > avian flu
10. http://www.wikipedia.org/ > search > adenovirus
11. http://www.wikipedia.org/ > search hepatitis
12. http://www.wikipedia.org/ > search > rabies

Done by:
Eugene and Phuiyuen, TG02

 

Fungi

Introduction
Fungi are eukaryotic cells that lack chlorophyll. They have cell walls and filamentous structures and produce spores, or conidia. These organisms grow as saprophytes that obtain nutrients from dead organic matter. Most of the fungi that cause systemic infections may infect incidental hosts (i.e. humans and other animals) who are exposed to fungal elements or spores.

Systemic mycoses

Histoplasma capsulatum

Epidemiology
Dimorphic fungus (exists as mold in soil and yeast in tissue) that is found worldwide and in temperate, subtropical and tropical climates. Grows in soil and material contaminated with bat or bird droppings.

Causes
Histoplasmosis. Infection occurs resulting from inhalation of spores.

Transmission

Infection resulting from inhalation of spores of the fungi in their mold forms in soil. Within the lungs, the spores differentiate into yeasts.

Signs & symptoms
Fever
Headache
Malaise
Myalgia (muscle pain)
Abdominal pain
Chills

Mode of control

No means of prevention except avoiding exposure in areas of endemic infection.


Dermaphytes

Trichophyton species
Trichophyton ajelloi (geophilic)
Trichophyton concentricum (anthrophilic)
Trichophyton flavescens (geophilic)
Trichophyton gloriae (geophilic)
Trichophyton interdigitale (anthrophilic)
Trichophyton megnini (anthrophilic)
Trichophyton mentagrophytes (zoophilic, anthrophilic) (rodents)
Trichophyton phaseoliforme (geophilic)
Trichophyton rubrum (anthrophilic) (most common)
Trichophyton schoenleinii (anthrophilic)
Trichophyton simii (zoophilic) (monkey, chicken)
Trichophyton soudanese (anthrophilic)
Trichophyton terrestre (geophilic)
Trichophyton tonsurans (anthrophilic)
Trichophyton vanbreuseghemii (geophilic)
Trichophyton violaceum (anthrophilic)
Trichophyton yaoundei (anthrophilic)

Epidermophyton floccosum


Epidemiology
Found worldwide, more common in countries with hot and humid climates with crowding or debilitation

Cause
Dermatophytosis
Tinea corporis (ringworm)
Tinea cruris (jock itch)
Tinea pedis (athlete’s foot)
Tinea manuum (hand)
Tinea favosa (scalp)
Folliculitis (inflammation of hair follicles)
Tinea capitis (hair infection)
Onychomycosis (nail infection)
Invasive infection for immunocompromised host

Transmission
Direct or indirect contact with infected host (human or animal)
Direct or indirect contact with skin or hair
Geophilic species are acquired via contact with spores in the soil
Skin trauma (burns, cuts), high temperature and humidity and increase susceptibility to infection

Signs & symptoms
Itching, stinging and burning between the toes, on the soles
Excessive dryness of the skin on the bottom of the feet
Thick, crumbly, discoloured, brittle and ragged nails
Blisters
Hair loss
Scabs
Tinea of the nails

Mode of control
No means of prevention except avoiding exposure in areas of infection

Microsporum species
Microsporum audouinii (anthrophilic)
Microsporum canis (zoophilic) (cats and dogs)
Microsporum cooeki (geophilic, zoophilic) (fur from cats, dogs and rodents)
Microsporum ferrugineum (anthrophilic)
Microsporum gallinae (zoophilic) (chicken)
Microsporum gypseum (geophilic)
Microsporum nanum (geophilic, zoophilic) (pig)
Microsporum persicolor (zoophilic) (rodents)

Epidemiology
Found worldwide, more common in countries with hot and humid climates with crowding or debilitation

Cause
Dermatophytosis
Tinea corporis (ringworm)
Tinea cruris (jock itch)
Tinea pedis (athlete’s foot)
Tinea manuum (hand)
Tinea favosa (scalp)
Tinea capitis (scalp)
onychomycosis (rare)
Invasive infection for immunocompromised host
Note: Microsporum persicolor does not infect hair

Transmission
Direct or indirect contact with infected host (human or animal)
Direct or indirect contact with skin or hair
Geophilic species are acquired via contact with spores in the soil
Skin trauma (burns, cuts), high temperature and humidity and increase susceptibility to infection

Signs & symptoms

Itching, stinging and burning between the toes, on the soles
Excessive dryness of the skin on the bottom of the feet
Thick, crumbly, discoloured, brittle and ragged nails
Blisters
Hair loss
Scabs
Tinea of the nails

Mode of Control

No means of prevention except avoiding exposure in areas of infection

Malassezia furfur


Epidemiology
Worldwide, part of normal skin flora, infections likely to occur in hot and humid conditions

Cause
Pityriasis versicolor (skin rash)
Seborrheic dermatitis (flaky scalp, face, trunk)
Folliculitis (inflammation of hair follicles)
Blepharitis (inflammation of the eyelids)
Tinea Blanca (hair)
Severe systemic infections in immunocompromised host

Transmission
Normal skin flora, that causes infection when it becomes an opportunistic infection

Signs and Symptoms
Itching
Scaling
However sometimes the infection is asymptomatic


Sporothrix schenckii

Epidemiology
Worldwide, isolated from soil, living and decomposing plants, wood and moss

Cause
Sporotrichosis (Rose handler’s disease)
Invasive sinusitis
Meningitis
Osteoarticular infection
Bursal infection

Transmission
Infection by entry of infecting fungus through the skin via minor trauma (eg. cuts)

Signs & symptoms

Large ulcerations
Small painless skin bump on the arms, fingers or hand
Boil-like lesions
Firm skin nodules
Suppurative nodules


EXCLUSION OF FUNGI

1. Opportunistic mycoses
These fungi cause infections only in immunocompromised people.

Candida species
Candida albicans
Candida guilliermondii
Candida parapsilosis
Candida tropicalis

Epidemiology
This fungus is found worldwide. For some of the fungi, they are part of the normal microbial flora of the mucous membranes of the mouth and intestinal tract.

Cryptococcus species
Cryptococcus neoformans
Cryptococcus gattii


Epidemiology
Cryptococcus neoformans is found in soil, especially those enriched by pigeon droppings
Cryptococcus gattii can be found in eucalyptus trees and decaying wood forming hollows in living trees

Aspergillus species
Aspergillus fumigatus
Aspergillus niger
Aspergillus flavus
Aspergillus terreus
Aspergillus nidulans


Epidemiology
Fungus is ubiquitous in the environment, growing in soil and decaying vegetation. The transmission of fungus is by airborne conidia.

2. Coccidioides immitis


Epidemiology
This fungus is found in arid regions of USA and South America

3. Blastomyces dermatitidis

Epidemiology
This fungus is endemic in North & South America, Africa and in the Middle East.


References
Martin
http://www.emedicine.com > search > Cryptococcosis
http://www.emedicine.com > search > Histoplasmosis
http://www.doctorfungus.org > search > Cryptococcus
http://www.mycology.adelaide.edu.au > search > Candida
Levinson, W. (2006). Review of Medical Microbiology & Immunology. San Francisco, California: Lange Medical Books/McGraw-Hill publishing company.
Murray, P.R. (2002). Medical Microbiology. St. Louis, Missouri: Mosby Inc.
Virella, G. (1997). Microbiology and Infectious Diseases. Pennsylvania, USA: Williams & Wilkins.

Randall
http://www.doctorfungus.org > search > Trichophyton
http://www.wrongdiagnosis.com > T > tinea
http://www.mayoclinic.com/ > health > search > athlete’s foot
http://www.emedicine.com/aaem/topic277.htm
http://www.doctorfungus.org > search > Epidermophyton
http://www.doctorfungus.org > search> Microsporum
http://www.doctorfungus.org > search > Malassezia furfur
http://www.doctorfungus.org > search > Sporothrix schenckii
http://www.wrongdiagnosis.com > S > sporotrichosis
Walker, T.S. (1998). Microbiology. Philadelphia, Pennsylvannia: W.B Saunders Company
Levinson, W. (2006). Review of Medical Microbiology & Immunology. San Francisco, California: Lange Medical Books/McGraw-Hill publishing company.

Done by: Martin Ng & Randall Chua (TG02)


 

Protozoa

Parasites
Parasites occur in two distinct forms: single celled protozoa and multi-cellular metazoan called helminthes. [1]

Helminthes
Metazoan are subdivided into two groups: Platyhelminthes and the Nemathelminthes.
The phylum Platyhelminthes contains two important classes: Cestodes and Trematoda. [1]

Cestodes are tapeworms. It consists of two main parts: a rounded head called the scolex which has specialized means of attaching to the intestinal wall and a flat body of multiple segments called proglottids. The oldest proglottids at the distal end produce many eggs which are excreted in the feces and transmitted to various intermediate hosts such as cattle, pigs and fish. Humans usually acquire the infection when undercooked flesh containing the larvae is ingested. [1,2]

Taenia solium: T. solium is found worldwide. Because pigs are intermediate hosts of the parasite, completion of the life cycle occurs in regions where humans live in close contact with pigs and eat undercooked pork. Taeniasis and cysticercosis are very rare in predominantly Muslim countries, as Islam forbids the consumption of pork.[1]

Taenia saginata: T. saginata, also known as Taeniarhynchus saginata or the Beef tapeworm, is a parasite of both cattle and humans, but which can only reproduce in humans. T. saginata occurs where cattle is raised, human feces is improperly disposed of, meat inspection programs are poor, and where meat is eaten without proper cooking.[1]

Echinococcus multilocularis: The definitive hosts are mainly foxes and the intermediate hosts are various rodents. Humans are infected by accidental ingestion of food contaminated with fox feces. [2]

Trematodes are transmitted to humans either via penetration of the skin by the free-swimming cercariae of the schistosomes or via ingestion of cyst in undercooked fish or crabs in Clonorchis and Paragonimus infection, respectively. [1]

Schistosoma japonicum: It causes schistosomiasis. It is found only in Asia and domestic animals such as water buffalos and pigs acts as reservoirs. It is common in tropical and subtropical climates. Most patients are asymptomatic, but chronic infections may become symptomatic. [1]

Nemathelminthes are also known as nematodes. They are commonly classified under: intestinal nematodes and tissue nematodes. Infections with nematodes are associated with conditions of poor hygiene. Such infections are extremely common throughout the tropics and subtropics. [1]

Ancylostoma duodenale and Necator americanus: Humans are infected when filariform larvae in moist soil penetrate the skin. They are found especially in tropical areas. [2]

Strongyloides stercoralis: They are found in the soil. It penetrates the skin and occurs primarily in the tropics, especially SEA.[1]

Wuchereria bancrofti : It occurs in tropical and subtropical areas and is endemic in central Africa, along the Mediterranean coast, and in many parts of Asia, including China, Korea, Japan and the Philippines. [1]


Protozoa

Protozoa are eukaryotic cells and have many of the intracellular components of characteristic of higher forms of life. Most protozoa have some form of active locomotion. Protozoa are found in soil, in most bodies of water, and in many higher forms of life. Relatively few protozoa are able to cause diseases in humans and most are beneficial contributors to the various biological cycles in nature.

Protozoa and other parasitic diseases are common in underdeveloped, tropical, and sub tropical area. The overall effects of these diseases on the general well-being of the inhabitants of these areas are of major importance.

The diagnosis, treatment, and control of protozoal diseases differ in some ways from those used for other microbial diseases. Because of the large size, distinct shapes of the protozoa and that protozoa are difficult to grow on media, direct microscopy is the routine method of diagnosis. The symptoms of many protozoal diseases are very general and often are not used solely as a basis for a specific diagnosis.
Control of protozoal disease is often difficult since human are not the primary host, effective vaccines are not currently available, anti- protozoal drugs are often toxic to the host and close contact between humans and the disease reservoir is fostered by poverty and inadequate education.

Some disease-producing protozoa have a life cycle that involves more than one type of host. The parasite goes through sexual reproduction in the definitive host, whereas asexual reproduction occurs in the intermediate human host. The cell types which are present in a host may be the growing trophozoite (damages tissues) and the dormant, resistant cyst (the form which survives outside a host perpetuating transmission by indirect means.


Reasons for inclusion:

Indonesia is a tropical country with high humidity. In places with high humidity, Food and water can be easily contaminated with fecal products of humans and animals. In the jungle, lakes and water bodies are common. Wild animals’ and human feces may contaminate water and food that the soldiers eat thus infecting them. Swimming in lakes and water bodies may also cause infections as some protozoa can be transmitted through mucosal membranes, trauma and ingestion. Usually in the army, personal hygiene is always overlooked, combined with the poor sanitation of the jungle, it can cause severe infection. During military training, there is also personal time. Soldiers may explore neighboring villages. The soldiers may get infected with diseases during sexual intercourse with women in neighboring villages. In the villages, they may also come into contact with domestic animals.


Entamoeba histolytica [1]

Epidemiology: It is a cosmopolitan intestinal parasite. Organism is acquired by ingestion of cysts that are transmitted primarily by the fecal-oral route in contaminated food and water. Anal- oral transmission, e.g., among male homosexuals, also occurs. There is no animal reservoir. Infection is found worldwide, but occur most frequently in tropical countries, especially in areas with poor sanitation. There are no animal reservoirs.

Causes: Amebic dysentery and liver abscess

Signs and Symptoms:
Asymptomatic infection is common.

Acute intestinal amebiasis: Dysentry (bloody, mucus-containing diarrhea) accompanied by lower abdominal discomfort, flatulence, and tenesmus

Chronic amebiasis: occasional diarrhea, weight loss, and fatigue. Granulomatous lesion called an ameboma may form in the cecal or rectosigmoid areas of the colon.

Amebic abscess (liver): right upper-quadrant pain, weight loss, fever, and a tender, enlarged liver. Right lobe abscesses can penetrate the diaphragm and cause lung disease. Aspiration of the liver abscess yields brownish-yellow pus with the consistency of anchovy-paste.

Mode of Control: Improving basic hygiene and sanitation practices is most effective way of controlling outbreaks of amebiasis as E. histolytica thrives in conditions where standards of sanitation and hygiene are poor. Avoid fecal contamination of food and water and observing good personal hygiene such as hand washing. Water supplies should be purified before drinking. Vegetables should be cooked as it may have been contaminated with human feces.


Giardia lamblia [1.2]

Epidemiology: This organism is a cosmopolitan parasite, common in temperate latitudes and in developed countries, as well as in the tropics. Transmission occurs by ingestion of the cyst in food and water contaminated by feces. The source of infection may be infected human carriers or wild animals that act as reservoirs of infection and contaminate water with the cysts passes in their feces. They pass cyst in the stool which then contaminates the water supplies. Outbreaks are usually related to contaminate water supplies. Drinking of untreated stream water will lead to infection.

Causes: Giardiasis

Signs and Symptoms: Non bloody, foul- smelling diarrhea, nauseam anorexia, flatulence, and abdominal cramps that persist for weeks or months

Mode of Control: Water should be boiled, filtered, or treated with iodine. Frequent hand washing and separation of feeding areas from sanitization area. No vaccine or preventive drug is available.


Plasmodium Species [1]

Epidemiology: The four species are P. vivax, P. falciparum, P. ovale and P. malariae. P. vivax and P. falciparum are the most common causes. The vector and definitive host is the female Anopheles mosquito. Disease is transmitted primarily by the bite of the mosquito. This occurs mainly in the tropical and subtropical areas, especially in Asia.

Causes: Malaria

Signs and Symptoms: Abrupt onset of fever and chills, accompanied by headache myalgias (muscle pain), and aethralgias (joint pains). Fever can reach up 41°C. It is accompanies by shaking chills, nausea, vomiting and abdominal pain. Splenomegaly and hepatomegaly is commonly seen and anaemia is prominent.

P. falciparum can cause extensive brain (cerebral malaria) and kidney (blackwater) damage. (large scale intravascular lysis)

Mode of Control: Chemoprophylaxis of malaria. The use of mosquito netting, window screens, protective clothing and insect repellent can lower the probability of mosquito bites. Elimination of breeding site includes drainage of stagnant water in swamps and ditches, removal of standing water and improvement in land drainage.


Toxoplasma gondii [2]

Epidemiology: Infection by T. gondii occurs worldwide. It is an obligate intracellular parasite widespread among wild and domestic animals. The definitive host is the domestic cat and other felines; humans and other mammals are intermediate host. Cockroaches, flies and earthworms serve as non-infected transport host. Infection begins with the ingestion of cyst in undercooked meats or from contact with cat feces.

Causes: Toxoplasmosis

Signs and Symptoms: Resemble infectious mononucleosis (fever, muscle soreness, sore throat, fatigue)

Mode of control: Control is difficult because of the diversity of animal reservoir. To prevent toxoplasmosis, cook meat thoroughly to kill cyst. Cat should not be fed raw meat as it is the definitive host of the obligate intracellular parasite.


Acanthamoeba castellanii [2]

Epidemiology: They are free-living amoebae. They are found in warm freshwater lakes and in soil. Infection can occur when swimming in the lakes and when there is skin trauma

Causes: Meningeoncephalitis

Signs and Symptoms: eye infection

Mode of Controls: Do not swim in lakes. Avoid traumatized skin contact with lake water or soil.


Naegleria fowleri [1,2]

Epidemiology: N. fowleri thrives in warm water at lower oxygen tensions. It is often found in the mud at the bottom of puddles, ditches, and lakes. It enters the body trough mucous membranes or inhalation while an individual is swimming.

Causes: Meningeoncephalitis

Signs and Symptoms: headache, fever and deteriorates rapidly into coma

Mode of Controls: Do not swim in lakes. Avoid traumatized skin contact with lake water or soil.


Cyclospora cayetanensis [2]

Epidemiology: It is distributed worldwide. Infection appears to be acquired by ingestion of oocytes in water or with contaminated fruits or vegetables.

Causes: “Traveler’s diarrhea”

Signs and Symptons: Water diarrhea with low grade fever and abdominal cramps

Mode of control: Treatment of water supplies with chlorination and filtration. Improving basic hygiene and sanitation practices is most effective way of controlling outbreaks.


Cryptosporidium parvum [1]

Epidemiology: Infection is usually water borne or acquired from animals. Oocytes are present in animal feces and can be transmitted to the human through the fecal- oral route.

Causes: cryptosporidiosis

Signs and Symptoms: Diarrhea leading to fluid loss and malnutrition

Mode of control: Improving basic hygiene and sanitation practices is most effective way of controlling outbreaks. Swimming in lakes or any bodies of water is not advisable.


Trichomonas vaginalis [1,2]

Epidemiology: The primary location is the vagina and the prostate. Transmission of this organism is by sexual contact. It is predominantly a vaginal parasite, although urethritis may occur in the male consorts of infected women. Infection in women is more severe than in men.

Causes: Urinary tract infection

Signs and Symptoms: Pain during urination, discharge

Mode of Control: Abstinence or no unprotected sex


Reasons for exclusion:

Trypanosoma cruzi (Chagas’ disease) [1]
Vector is the reduviid bug. Animal reservoirs include wild species such as the armadillo, raccoon and rat. Rats are commonly found in jungles. However, this disease is common in America only.

Trypanosoma brucei rhodesiense (sleeping sickness) [1]
Wild animals as reservoirs for the tsetse fly, Glossina. Wild animals are abundant in jungles. But this disease occurs primarily in West Africa therefore it is ruled out.

Leishmania donovani [1]
Lifecycle involves the sandfly as the vector and a variety of mammals such as dogs, foxes and rodents as reservoirs. However, this is common in Middle East, Africa, Russia, India and China

Babesia [1,2]
Human infection is rare. Cases reported in Africa, New York, and Southern Europe. In immunocompetent individuals the disease is usually self limiting, so no specific treatment is required.

Isopora belli [2]
It causes self limiting diarrhea in immunocompetenet individuals, but in more severe cases, particularly in patients that are immunocompromised (e.g. AIDS), they will cause severe diarrhea. Medical screening is usually done before enlistment to determine if the individual is healthy. If the individual is immunocompromised, it can be detected during the screening.

Balantidium coli [1,2]
Domestic animals, especially pigs are the main reservoir for the organism. It is commonly associated with pig farming. Humans are infected after ingestion of the cyst in food or water contaminated with animal or human feces. However, it rarely causes disease in humans. Most individual are asymptomatic; diarrhea rarely occurs.


References:
1)Levinson, W. (2006). Review of Medical Microbiology and Immunology. San Francisco,California: Lange Medical Books/ McGraw-Hill Medical Publishing Division

2)Murray, P.R. (2002). Medical Microbiology. St. Louis, Missouri: Mosby Inc.


Done by:
Foo Yong Yang
Loh Mun Jo-anne
TG02

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