Moodle 4

DefinitionDefinition

Anthrax is an Anthrax is an acuteacute diseasedisease, caused by , caused by Bacillus anthracisBacillus anthracis. It affects both humans . It affects both humans and animals. The name 'anthrax' comes and animals. The name 'anthrax' comes from anthrax [from anthrax [άνθραξάνθραξ], ], thethe GreekGreek wordword forfor''coalcoal', ', becausebecause ofof thethe blackblack skinskin lesionslesionsdevelopeddeveloped byby victimsvictims withwith a a cutaneouscutaneousanthraxanthrax infectioninfection..

EtiologyEtiology

Bacillus anthracisBacillus anthracis is a is a rodrod--shaped, shaped, GramGram--positivepositive, aerobic , aerobic bacterium, about 1 by bacterium, about 1 by 9 micrometers in size 9 micrometers in size and is usually straight and is usually straight but may be slightly but may be slightly curved. The ends of curved. The ends of the bacilli are the bacilli are truncated, not truncated, not rounded. rounded.

GramGram--positive positive anthraxanthrax bacteria bacteria (purple rods) in (purple rods) in cerebrospinal cerebrospinal

fluidfluid sample. If present, a Gramsample. If present, a Gram--negative bacterial species would negative bacterial species would appear pink. (The other cells are appear pink. (The other cells are

white blood cellswhite blood cells).).

Polychrome Polychrome methylenemethylene blue stain blue stain

of of Bacillus Bacillus anthracisanthracis.. Image Image

courtesy of Anthrax Vaccine courtesy of Anthrax Vaccine

Immunization Program Agency, Immunization Program Agency,

Office of the Army Surgeon Office of the Army Surgeon

General, United StatesGeneral, United States..

Anthrax bacilli tend to Anthrax bacilli tend to form into long chains. form into long chains. B. B. anthracisanthracis produces produces a capsule that is a capsule that is easily visualized using easily visualized using a a methylenemethylene blueblue. .

EtiologyEtiology

LymeLyme DiseaseDisease

Lyme disease, or lyme borreliosis, is the tickLyme disease, or lyme borreliosis, is the tick--borne infectious disease caused by borne infectious disease caused by Borrelia Borrelia burgdorferiburgdorferi and characterized by and characterized by feverfever, , headacheheadache, , fatiguefatigue, , depressiondepression, and a , and a characteristic circular skin rash called characteristic circular skin rash called erythema erythema migransmigrans. The disease is named after the town of . The disease is named after the town of LymeLyme, , ConnecticutConnecticut, USA, where a number of , USA, where a number of cases were identified in 1975.cases were identified in 1975.

EtiologyEtiology

Lyme disease is Lyme disease is caused by caused by Borrelia Borrelia burgdorferiburgdorferi from the from the genusgenus BorreliaBorrelia. It is . It is ggramram--negativenegativespirochetalspirochetal bacteriabacteria..

Borrelia bacteria, the causative agent of Lyme disease. Magnified

400 times.

EpidemiologyEpidemiology

Lyme disease is classified Lyme disease is classified as a as a zoonosiszoonosis, as it is , as it is transmitted to humans transmitted to humans from a from a natural reservoirnatural reservoiramong rodents by among rodents by ticksticksthat feed on both sets of that feed on both sets of hostshosts. Hard. Hard--bodied ticks bodied ticks of the genus of the genus IxodesIxodes are are the main the main vectorsvectors of Lyme of Lyme disease. disease.

Ixodes scapularis, the vector of Lyme disease

EpidemiologyEpidemiology

A tick must be A tick must be attached to a person attached to a person for 2for 2--3 days to result 3 days to result in infection. This is in infection. This is due to the life cycle of due to the life cycle of B. B. burgdorferiburgdorferi in ticks. in ticks.

Normal and engorged Ixodesticks.

Physical examPhysical exam

The manifestations of The manifestations of LymeLyme disease have disease have been divided into 3 been divided into 3 stages: localized, stages: localized, disseminated, and disseminated, and persistent. The first 2 persistent. The first 2 stages are part of the stages are part of the early infection, while early infection, while persistent disease is persistent disease is considered late considered late infection. The primary infection. The primary symptoms of stage 1 symptoms of stage 1 are are erythemaerythemamigransmigrans. .

Common bullseye rash pattern associated with Lyme disease

Physical examPhysical exam

Erythema migrans, the characteristic rash of early Lyme disease.

LymeLyme DiseaseDisease

Avoidance of ticks and areas associated with ticks Avoidance of ticks and areas associated with ticks

�� The highest concentration of ticks is found in The highest concentration of ticks is found in wooded areas. wooded areas.

�� Individuals should try to prevent ticks from Individuals should try to prevent ticks from getting onto skin and crawling to preferred getting onto skin and crawling to preferred areas. areas.

�� Long hair should be worn under a hat. Long hair should be worn under a hat.

�� Wearing longWearing long--sleeved shirts and tucking long sleeved shirts and tucking long pants into socks is recommended.pants into socks is recommended.

LymeLyme DiseaseDisease

InspectionInspection�� Because the above recommendations are not Because the above recommendations are not

always practical, particularly for children and always practical, particularly for children and during the summer, and because ticks do not during the summer, and because ticks do not appear to transmit appear to transmit LymeLyme disease until they disease until they have been attached for several days, close have been attached for several days, close inspection for ticks should be performed each inspection for ticks should be performed each time one has been outdoors. time one has been outdoors.

�� The groin, The groin, axillaaxilla, and hairline should be , and hairline should be inspected particularly well.inspected particularly well.

MalariaMalaria

MalariaMalaria isis a a mosquitomosquito--borneborne infectiousinfectious diseasediseasecausedcaused byby plasmodiumplasmodium parasiteparasite. It . It isis widespreadwidespreadinin tropicaltropical andand subtropicalsubtropical regionsregions, , includingincludingpartsparts ofof thethe AmericasAmericas (22 (22 countriescountries), ), AsiaAsia, , andandAfricaAfrica. . EachEach yearyear, , therethere areare approximatelyapproximately 350350––500 500 millionmillion casescases ofof malariamalaria, , killingkilling betweenbetween oneoneandand threethree millionmillion peoplepeople

EtiologyEtiology

�� The four The four PlasmodiumPlasmodium species known to cause species known to cause malaria include:malaria include:�� PlasmodiumPlasmodium falciparumfalciparum

�� PlasmodiumPlasmodium vivaxvivax

�� PlasmodiumPlasmodium ovaleovale

�� PlasmodiumPlasmodium malariaemalariae. .

EtiologyEtiology

Plasmodium vivax Plasmodium ovale

Plasmodium falciparum Plasmodium malariae

EpidemiplogyEpidemiplogy

MalariaMalaria isis naturallynaturallytransmittedtransmitted byby thethebitebite ofof a a femalefemaleAnophelesAnopheles mosquitomosquito. .

Anopheles albimanus mosquito feeding on a human arm. This mosquito is a vector of malaria and mosquito control is a very effective way of reducing the

incidence of malaria.

EpidemiplogyEpidemiplogy

Countries which have regions where malariais endemic as of 2003 (coloured yellow). Countries in green are free of indigenous

cases of malaria in all areas.

Malaria causesabout 250 millioncases of fever andapproximately onemillion deathsannually. The vastmajority of casesoccur in childrenunder 5 years old; pregnant womenare also especiallyvulnerable

EpidemiplogyEpidemiplogy

Frequency of malaria cases in 1996