Infection Case Infection Case

► Int 1 Int 1 曾耀弘曾耀弘

Instructed by : Professor Instructed by : Professor 盧章智盧章智Date:2005/12/12Date:2005/12/12

CaseCase

► A 35 year old male medical student from A 35 year old male medical student from Kenya, who was studying in the United Kenya, who was studying in the United States, presented to a hospital ER room in States, presented to a hospital ER room in Boston, Mass, after a trip home to visit Boston, Mass, after a trip home to visit relatives. relatives.

► His symptoms consisted of nausea, His symptoms consisted of nausea, vomiting, fever, malaise, night sweats, and vomiting, fever, malaise, night sweats, and

severe shaking chills.severe shaking chills.

► These symptoms had persisted for several These symptoms had persisted for several weeks, chills and fever occurred weeks, chills and fever occurred periodically, usually at 36 to 48h intervals. periodically, usually at 36 to 48h intervals.

► An enlarged spleen was detected on PE An enlarged spleen was detected on PE examination. examination.

► Blood was drawn for lab tests, including Blood was drawn for lab tests, including platelet count, a complete blood count and platelet count, a complete blood count and thick and thin blood smears.thick and thin blood smears.

► The results of the CBC revealed that the patient The results of the CBC revealed that the patient was anemic (hemoglobin, 9.0g/dl) and thrombowas anemic (hemoglobin, 9.0g/dl) and thrombocytopenic ( platelets, 30,000/ul). cytopenic ( platelets, 30,000/ul).

► Thick and thin smears were prepared and staineThick and thin smears were prepared and stained using the Giemsa method. d using the Giemsa method.

► Microscopic examination of these films revealed Microscopic examination of these films revealed the presence of a large number (average of three the presence of a large number (average of three parasites per oil immersion field of intra erythroparasites per oil immersion field of intra erythrocytic parasitic forms, mostly in the shapes of smcytic parasitic forms, mostly in the shapes of small rings.all rings.

► A few cells contained multiple rings. A rarA few cells contained multiple rings. A rare banana-shaped gametocyte was seen se banana-shaped gametocyte was seen some early ring trophozoites were identifieome early ring trophozoites were identified as applique forms.d as applique forms.

► Several blue rings with two red chromatiSeveral blue rings with two red chromatin dots were seen. n dots were seen.

►A small number of irregular dark bluish A small number of irregular dark bluish red dots were also seen in the red dots were also seen in the erythrocytes. erythrocytes.

►The red blood cells were normal in size The red blood cells were normal in size and exhibited no stippling. and exhibited no stippling.

► Based on these findings a diagnosis of Based on these findings a diagnosis of infection with a blood parasite was infection with a blood parasite was mademade

questionsquestions

► 1. which infection does this patient have ? 1. which infection does this patient have ? ► Ans: MalariaAns: Malaria

► Which parasite is infecting him? Which parasite is infecting him? ► Ans: plasmodia falciparum. Ans: plasmodia falciparum.

► presence of dots or clefts on the red blood presence of dots or clefts on the red blood cells are the main differential characteristicells are the main differential characteristics. cs.

► A rare banana-shaped gametocyte was seA rare banana-shaped gametocyte was seen some early ring trophozoites were ideen some early ring trophozoites were identified as applique forms.ntified as applique forms.

Describe the typical appearance of this parasite in thick and thin GiemDescribe the typical appearance of this parasite in thick and thin Giemsa stained smears. What are the red dots seen in the smear?sa stained smears. What are the red dots seen in the smear?

► P. P. falciparumfalciparum: micro and macrogametocyt: micro and macrogametocytes are easily recognized by their crescenties are easily recognized by their crescentic, cigar or banana like shape. c, cigar or banana like shape.

► Micro gametocytes have a diffuse chromatMicro gametocytes have a diffuse chromatinin

► while macrogametocytes have thickened while macrogametocytes have thickened chromatin. Mirogametocyte, Giemsa thin chromatin. Mirogametocyte, Giemsa thin smear.smear.

► P.P.falciparumfalciparum: in thick films red blood cells : in thick films red blood cells are not visible and leucocytes and parasitare not visible and leucocytes and parasites appear smaller than in thin smears. es appear smaller than in thin smears.

► Trophozoites have a ring or comma shape.Trophozoites have a ring or comma shape. With one or two dots of chromatin. With one or two dots of chromatin.

► The pigment, when present is compact. The pigment, when present is compact.

► Plasmodium falciparum: Blood Stage ParPlasmodium falciparum: Blood Stage Parasites: Thick Blood Smears asites: Thick Blood Smears

► P. falciparum:P. falciparum: trophozoites are small rings trophozoites are small rings with single or double small chromatin dotwith single or double small chromatin dots, and regular cytoplasm; s, and regular cytoplasm;

► multiple infection and multiple infection and high parasitemia (>5%) are common. high parasitemia (>5%) are common.

►

Dots or cleft (Maurer's) can be observed oDots or cleft (Maurer's) can be observed on the infected RBCs. n the infected RBCs.

P.falciparumP.falciparum trophozoites, thin sm trophozoites, thin smear, Giemsa stain.ear, Giemsa stain.

What are the applique forms seen iWhat are the applique forms seen in the blood smear?n the blood smear?

► Early ring form of plasmodium falciparum Early ring form of plasmodium falciparum found at the margin of the red cell found at the margin of the red cell

► sometimes trophozoites appear at the edsometimes trophozoites appear at the edge of the red blood cell ( applique form) . ge of the red blood cell ( applique form) .

► Erythrocytes maintain regular shape and sErythrocytes maintain regular shape and size. ize.

Describe the clinical illness caused by this parasite. Describe the clinical illness caused by this parasite.

Explain the severity of symptoms in this patientExplain the severity of symptoms in this patient. .

►The incubation period varies generally The incubation period varies generally between 10-30 days. between 10-30 days.

►As the parasite load becomes As the parasite load becomes significant, the patient develops significant, the patient develops headache, lassitude, vague pains in headache, lassitude, vague pains in the bones and joints chilly sensations the bones and joints chilly sensations and fever. and fever.

► As the disease progresses, the chills and feAs the disease progresses, the chills and fever become more prominent. ver become more prominent.

► The chill and fever follow a cyclic pattern( The chill and fever follow a cyclic pattern( PAROXYSM) with the symptomatic period PAROXYSM) with the symptomatic period lasting 8-12 hours. lasting 8-12 hours.

► Each paroxysm is due to the rupture of infEach paroxysm is due to the rupture of infected erythrocytes and release of parasiteected erythrocytes and release of parasites. s.

Why is infection by this species considered to be more Why is infection by this species considered to be more serious than infection caused by other species?serious than infection caused by other species?

► This organism causes sequestration of caThis organism causes sequestration of capillary vasculature in the brain, gastrointepillary vasculature in the brain, gastrointestinal and renal tissues. stinal and renal tissues.

► Chronic malaria results in splenomegaly, Chronic malaria results in splenomegaly, hepatomegaly and nephritic syndromes. hepatomegaly and nephritic syndromes.

► P P falciparumfalciparum will be will eventually result will be will eventually results in death.s in death.

► renal failure may result from sequestration of RBCs renal failure may result from sequestration of RBCs and alteration of the renal microcirculation. and alteration of the renal microcirculation. Glomerulal and interstitial vessels present RBCs adherinGlomerulal and interstitial vessels present RBCs adhering to the endotheliumg to the endothelium

► P.falciparum:P.falciparum: severe severe P.falciparumP.falciparum infections are infections are clinical forms characterized by clinical forms characterized by

► potentially fatal manifestations or complicationpotentially fatal manifestations or complications:cerebral malaria, s:cerebral malaria, defined by a state of unrousable coma in absencdefined by a state of unrousable coma in absence of other causese of other causes

►

Celebral malaria: parasitized RBCs in braiCelebral malaria: parasitized RBCs in brain vessels (H&E stain). most common manin vessels (H&E stain). most common manifestationfestation. .

Describe the life cycle of this Describe the life cycle of this parasite?parasite?

► Malarial parasites are transmitted by the infecteMalarial parasites are transmitted by the infected female anopheline mosquito which injects spod female anopheline mosquito which injects sporozoites present in the saliva of the insect. rozoites present in the saliva of the insect.

► Sporozoites infect the liver paranchymal cells wSporozoites infect the liver paranchymal cells where they may remain dormant or undergo staghere they may remain dormant or undergo stages of schizogony to produce schizonts and meroes of schizogony to produce schizonts and merogony to produce merozoites. gony to produce merozoites.

► When parenchymal cells rupture. Thousands of When parenchymal cells rupture. Thousands of moronts are released into blood and infect the rmoronts are released into blood and infect the red cells. ed cells.

► Young schizont with 10 nuclei Young schizont with 10 nuclei

► Mature schizont with 24 nuclei, ready to rMature schizont with 24 nuclei, ready to rupture upture

► P P falciparumfalciparum infects both immature red bl infects both immature red blood cells and mature red cells. ood cells and mature red cells.

► In red cells, the parasites mature into tropIn red cells, the parasites mature into trophozoites. hozoites.

► These trophozoites undergo schizogony aThese trophozoites undergo schizogony and merogony in red cells which ultimately nd merogony in red cells which ultimately burst and release daughter merozoites. burst and release daughter merozoites.

► Increasingly mature trophozoites Increasingly mature trophozoites

► Some of the merozoites transform into malSome of the merozoites transform into male and female gametocytes while other entee and female gametocytes while other enter red cells to continue the erythrocytic cyclr red cells to continue the erythrocytic cycle. e.

► The gametocytes are ingested by the femaThe gametocytes are ingested by the female mosquito. le mosquito.

► The female gametocyte transforms into ooThe female gametocyte transforms into ookinete, is fertilized and forms an oocyst in tkinete, is fertilized and forms an oocyst in the gut. he gut.

► Plasmodium Plasmodium falciparumfalciparum

► The oocyte produces sporozoites which mThe oocyte produces sporozoites which migrate to the salivary gland and are ready tigrate to the salivary gland and are ready to infect another host. o infect another host.

► Malaria can be tranmitted by transfusion Malaria can be tranmitted by transfusion and transplacentally. and transplacentally.

In addition to thick and thin blood smears, In addition to thick and thin blood smears, which other laboratory techniques are which other laboratory techniques are

available to diagnose the infectionavailable to diagnose the infection► Malaria diagnosis relies on observation of parasites in Giemsa-sMalaria diagnosis relies on observation of parasites in Giemsa-s

tained thin or thick smears (G-TS). tained thin or thick smears (G-TS). ► thin film gives more informations on parasite morphology thin film gives more informations on parasite morphology

and permits an easier morphologic differentiationand permits an easier morphologic differentiation ►

Alternative techniques for identification of malaria parasites arAlternative techniques for identification of malaria parasites are based on fluorochromes such as e based on fluorochromes such as AcridineAcridine Orange (AO) Orange (AO), , DAPI-PIDAPI-PI o or BCP. r BCP.

► With these dyes malaria parasites are easily recognized under UWith these dyes malaria parasites are easily recognized under UV light, reducing the time spent reading the slides. V light, reducing the time spent reading the slides.

► P.falciparum: P.falciparum: staining with fluorochromes is rapid (less than 1 staining with fluorochromes is rapid (less than 1 min) and observation of slides can be performed at low magnifimin) and observation of slides can be performed at low magnification (400X) allowing rapid screening of smears even with low cation (400X) allowing rapid screening of smears even with low

parasitemiaparasitemia..

► quantitative buffy coat (QBC) (Becton-Dickinson) anaquantitative buffy coat (QBC) (Becton-Dickinson) analysis uses AO staining of centrifuged parasites in a calysis uses AO staining of centrifuged parasites in a capillary tube containing a float, has been shown to be pillary tube containing a float, has been shown to be rapid and accuraterapid and accurate

► P.falciparumP.falciparum trophozoites. Acridine Orange stain trophozoites. Acridine Orange stain

► P.falciparum:P.falciparum: the sensitivity of different isolates of the sensitivity of different isolates of P.P.falciparumfalciparum to drugs to drugs can be assessed with the WHO "in vitro test". can be assessed with the WHO "in vitro test". The development to mature schizont in presence of tThe development to mature schizont in presence of therapeutic levels herapeutic levels of the drug demonstrates resistance of the isolate.of the drug demonstrates resistance of the isolate.

How would this infection be How would this infection be treated? treated?

► Treatment is effective with various quininTreatment is effective with various quinine derivatives( chloroquine, meflaquine ane derivatives( chloroquine, meflaquine and primaquine, etc.) d primaquine, etc.)

► Drug resistance, particularly in P. Drug resistance, particularly in P. falciparfalciparumum is a problem. is a problem.

► Control measures are eradication of infectControl measures are eradication of infected anopheline mosquitos. ed anopheline mosquitos.

► Vaccines are being developed and tried bVaccines are being developed and tried but none is available yet for routine use. ut none is available yet for routine use.