treat fungal, protozoal and helminthic infections 003.11

Treat Fungal, Protozoal and Helminthic Infections

003.11

Outline

• What is an opportunistic infection?

• Describe the epidemiology, signs and symptoms, diagnosis, treatment and preventative measures of:

– Fungal infections

• Histoplasmosis

• Aspergillosis

• Systemic /Superficial Candidiasis

Outline

• Malaria

• Describe the the epidemiology, signs and symptoms, diagnosis, treatment and prevention for:

– Amoebiasis, Giardiasis, Trichomoniasis, Toxoplasmosis & Pneumocystis carnii

• Describe the epidemiology, signs and symptoms, diagnosis, treatment and prevention for the following helminthic diseases:

– Nematodes, Cestodes & Trematodes

Opportunistic infections

• Definition – is any infection that results from a defective immune

system that is unable to defend itself against pathogens found in the normal environment

– Host defence mechanisms such as physiologic, anatomic or immunologic may be altered by disease, trauma, procedures or agents used for diagnosis or therapy

– Normally, fungal growth in the body is kept in check by harmless bacteria that compete with the fungus for food

Deep Fungal Infections

• Histoplasmosis

• Aspergillosis

• Systemic Candidiasis

Histoplasmosis

• Has several forms– asymptomatic

– acute histoplasmosis

– progressive disseminated

– chronic progressive pulmonary

– disseminated disease in the profoundly immunocompromised

Histoplasmosis

• Treatment– for progressively localized disease and for mild to

moderately severe nonmeningeal disseminated disease in immunocompetent or immunocompromised patients:

• Itraconazole or Ketaconazole

• duration of therapy ranges from weeks to several months depending upon severity.

Histoplasmosis

• Treatment– for patients who cannot take oral medications, who

have failed itraconazole therapy or who have meningitis and for management of severe disseminated disease in an immunocompromised host:

• Amphotericin B up to 2.5 g total may be needed

• Oral itraconazole may be given once condition stabilized

– patients with AIDs-related Histoplasmosis require lifelong suppressive therapy with itraconazole

Histoplasmosis

• Prevention– minimize exposure to contaminated areas such as caves

or chicken coop areas

– spray contaminated or suspect areas with water or oil

– wear protective masks

Aspergillosis

• Epidemiology & Etiology– caused by

• Aspergillus Fumigatus, A. Niger, and A. Flavus

– infection caused by inhalation of mold, leading to hyphal growth and invasion of blood vessels, hemorrhagic necrosis, infarction and potential dissemination to other sites in susceptible patients

Aspergillosis

• Epidemiology & Etiology– found in world wide in decaying vegetation,

insulation, air conditioning or heating venting, operating and patient rooms, on medical instruments and in airborne dust

– acquired by inhalation or occasionally by direct invasion in areas of damaged skin

– major risk factors include neutropenia, long term high dose corticosteroid use, transplants, heredity disorders or occasionally AIDs

Aspergillosis

• Treatment• Fungal Balls

– do not respond to antifungal therapy– resection may be required

• Invasive– Amphotericin B

• Allergic– oral prednisone – Itraconazole

Aspergillosis

• Prevention– monitoring of food with high levels of aflotoxins

– avoidance

– proper disposal of old foodstuff, decaying hay etc.

– proper and regular maintenance of air conditioning and heating units

– maintenance of good health

*Systemic Candidiasis*

• Epidemiology– invasive infection caused by Candida causing:

• Esophagitis (most common)

• Hepatosplenic involvement

• Fungemia (presence of fungi in the blood)

• Endocarditis

• Meningitis

Systemic Candidiasis

• S&S• Esophagitis - odynophagia, dysphagia

• Respiratory inf. - nonspecific, such as cough

• Endophthalmitis - white retinal plaques

• Fungemia - fever, fluffy white retinal infiltrates

• Endocarditis -secondary to fungemia


• Diagnosis– cultures from sputum, mouth, vagina, urine, blood.

– presence of characteristic lesion

– positive cultures of blood, CSF, pericardium or pericardial fluid or tissue biopsy specimens provide definitive evidence


• Prevention– detection and treatment of oral or vaginal infections as

soon as possible

– maintenance of good health in immunocompromised personnel i.e. Diabetics and HIV

Superficial Fungal Infections

Candidiasis

Outline

• Malaria– clinical presentation, pathophysiology, diagnostic

criteria, transmission and management of malaria sub-types

• PLASMODIUM Falciparum

• PLASMODIUM Vivax

• PLASMODIUM Ovale

• PLASMODIUM Malariae

• Plasmodium knowlesi

Malaria

• Epidemiology & Etiology– a disease caused by a minute unicellular parasite

known as PLASMODIUM

– part of the life cycle is spent in man and part in the mosquito

– major cause of ill health in many tropical and sub-tropical areas

– imported cases reported in Canada

– found worldwide due to imported cases

Malaria

• Epidemiology & Etiology– although the disease has been eradicated from most

temperate zone countries, it continues to be endemic in many parts of the tropics and subtropics & imported cases occur in the USA & other countries free of transmission

– especially dangerous to young children and pregnant women

Malaria

• Endemic area: Malaria is present in parts of Mexico, Haiti, Dominican Republic, Central & South America, Africa, the Middle East, the Indian subcontinent, Southeast Asia, China and Oceania

Malaria (Species )

• Malaria has 4 different species – most common are (>95% of clinical cases)

1. Plasmodium Vivax (80%)

2. Plasmodium Falciparum (15%)

– less common is

3. Plasmodium Malariae

– rare is

4. Plasmodium Ovale

Malaria

• Epidemiology & Etiology– P. vivax & P. falciparum are responsible for most

infections & are found through out the regions which have malaria

– P. falciparum is the predominant species in Africa & the only plasmodium in Haiti & the Dominican Republic

– P. malariae is also widely distributed but is less common

Malaria

• Epidemiology & Etiology– P.ovale although generally rare, seems to replace P.

vivax in West Africa.

– P.vivax infection is uncommon among black people because their red blood cells do not have the Duffy surface antigen, which is required for the invasion of the RBC’s

– humans are the only important reservoirs for malaria

Malaria

• Transmission– infected mosquito bites man and injects parasites into

blood stream

– congenital transmission

– blood infusion with infected blood

Malaria

• Incubation period– Falciparum

• 12 days (7 - 25)

– Vivax and Ovale

• 14 days (8 - 27)

– Malariae

• 30 days (16 days - 8 wk)

Malaria

• Essentials for diagnosis– history of exposure in a malaria-endemic area

– periodic attacks of sequential chills, fever & sweating

– headache, myalgia, splenomegaly, anemia and leukopenia

– characteristic parasites in erythrocytes, identified in thick or thin blood films

Malaria

• Essentials for diagnosis– complications of P. Falciparum malaria

• cerebral findings (mental disturbances, neurological signs, convulsions)

• hemolytic anemia

• hyperpyrexia

• dysenteric or cholera-like stools

• dark urine

• anuria

Malaria

• P. vivax & P. ovale– rarely compromise the function of vital organs

– mortality is rare and if it does occur is from splenic rupture

• P. malariae– often no acute symptoms

– low level paristemia may persist for decades

– is the most common cause of transfusion malaria

Malaria

• Signs & Symptoms– typical malarial attacks show sequentially over 4-6

hours

– shaking chills (the cold stage)

– fever to 410 or higher (the hot stage)

– marked diaphoresis (the sweating stage)

Malaria

• Associated symptoms may include:– fatigue, headache & dizziness

– GI symptoms

– myalgia, arthralgia & backache

– dry cough

– Splenomegaly usually appears when acute symptoms have continued for 4 days or more

– Anemia and jaundice are common manifestations

Malaria

• P. falciparum– causes the most severe disease and can be fatal if

untreated

– can cause a rapidly fulminating disease characterized by persistent high fever and orthostatic hypotension

– infection can lead to capillary obstruction and death if treatment is not prompt

Malaria

• Disease Cycle– infected female anopheles mosquito bites person– releases parasites into bloodstream– parasite enters RBC and multiplies causing the RBC to

burst– billions of RBC burst at the same time liberating

parasites– massive discharge causes high fever / shivering– temperature falls until new batch of parasites evolve– signs and symptoms start again

Atovaquone/Proguanil

Primaquine

Chloroquine

Doxycycline

Mefloquine

Primaquine

Malaria (Cycle)

• S & S with the cycle– either from onset or with progression of the disease, the

attacks may show:

• an every other day (tertian) periodicity such as in falciparum, ovale or vivax

• an every third day (quartan) periodicity in malariae

• After the primary episode, recurrences are common with each separated by a latent period

Malaria

• Management – all species except chloroquine resistant P. falciparum

• Chloroquine often combined with primaquine for P. vivax & P. ovale

• for severe attacks - parental quinine dihydrochloride

– for chloroquine resistant P. Falciparum – quinine plus one other – doxycycline, clindamycin or others as listed in table

Malaria

• Prophylaxis– when out of doors between dusk and dawn use

protective clothing,insect repellant which contains DEET

– screens should cover bedroom doors and windows– mosquito nets are a must– aerosols should be sprayed indoors, preferably with the

doors and windows closed, in the early evening– burning mosquito mats and coils is a fairly effective

means of keeping mosquitoes at bay during the night

Prophylaxis

• Preventive Drugs – Chloroqine sensitive:

• Chloroquine - 500mg/week while in area starting 1 week before and continue for 4 week after departing

– Chloroquine resistant:• Malarone – one tab daily starting the day before

entering the area and continue for 7 days after • Mefloquine – 250mg tab once a week starting 3

weeks before and continue for 4 weeks after• Doxycycline – 100mg/daily start 2 days before and

continue with for 4 weeks after

Prophylaxis

• Other points to remember– compliance with medication regime is of utmost

importance for maximum effectiveness– symptoms can appear up to six months after leaving a

malaria area – consult as soon as the following symptoms appear:

fever, rigors, headache, sweating abdominal pain, diarrhea, loss of appetite, nausea, slight jaundice, cough and enlarged liver and spleen

• www.who.int/ith/

Malaria

• Case reporting of malaria– all cases of malaria occurring in CF members, military

members of other forces, dependants or other civilians who receive their medical care from the CF are to be reported IAW Current CF Regulations and Orders.

Outline

• Describe the epidemiology, signs and symptoms, diagnosis, treatment and preventive measure for:– Amoebiasis

– Giardiasis

– Trichomoniasis

– Toxoplasmosis

– Pneumocystis carini

Amebiasis (Dysentery)

• Epidemiology– is infection of the large colon, liver and other tissues

caused by the protozoan parasite Entamoeba histolytica

– infection results from ingestion of mature cysts found on fecally contaminated food or water or through person to person

– humans are the only established host and are universally susceptible

Amebiasis

• S & S Non-invasive infection (up to 99%)– asymptomatic (90%)

– mild diarrhea

– abdominal discomfort

– even though asymptomatic can still pass infective cysts in stool

Amebiasis

• S & S Intestinal infection– intestinal symptoms can range from mild to moderate

(nondysenteric) to severe colitis (dysenteric colitis)– abdominal pain & tenderness– fatigue and wt loss– flatulence, rectal pain, diarrhea / bloody stools– fever uncommon initially but as infection increases so

does occurrence of fever– prostration and systemic toxicity which can lead to

death

Amebiasis

• S & S Extraintestinal infection– fever (often very high)

– pain (continuous, stabbing, or pleuritic and often very severe)

– systemic toxicity

– enlarged and tender liver (Amebic Liver Abscess)

– nausea & vomiting

– diarrhea 50%

– hematuria, dysuria, urinary frequency & urgency

Amebiasis

• Diagnosis (laboratory)– stool for ova & parasites– diarrheal stool should be examined immediately for

trophozoites and cysts in ordinary stool• repeated as necessary

– serologic test• indirect hemaglutination (IHA), positive in 85% of

colitis patients with extraintestinal disease• should be done in patients with idiopathic

inflammatory bowel disease to rule out amebiasis

Amebiasis

• Treatment– Asymptomatic intestinal infection

• Iodoquinol

– Mild to Moderate intestinal

• Metronidazole (flagyl) plus iodoquinol

– Severe Intestinal

• Metronidazole (for trophozoites) plus iodoquinol (luminal agent for protozoan).

• Parental administration may be required

Amebiasis

• Treatment cont’d– Extraintestinal

• Metronidazole plus iodoquinol

• if hepatic abscess present add Chloroquine

– General Considerations

• fluid, electrolyte and nutritional balance

• pain control

Amebiasis

• Prevention– avoid water or food that might be contaminated

– sanitary disposal of feces

– proper handwashing especially in food handlers

– proper water treatment – hyperchlorination/iodine treatment

– proper food storage – not allowing fly contamination

– good personal hygiene

Giardiasis

• Epidemiology– small intestinal infection caused by a flagellated

protozoan parasite - giardia lamblia– results from ingestion of trophozites which rapidly turn

into environmentally resistant cysts which in turn are passed in stool

• Transmission– cysts are transmitted as a result of fecal contamination

of water or food, by person to person or by anal-oral sexual contact

Giardiasis

• Signs & symptoms– may be asymptomatic (25 – 50%) or cause clinical

manifestations from intermittent flatulence to chronic malabsorption

– acute or chronic diarrhea, mild to severe with bulky, greasy, frothy, malodorous stools which are free of blood and pus

Giardiasis

• Signs & symptoms– upper abdominal discomfort, cramps, distension,

excessive flatulence and weakness are typical

– weight loss (from malabsorption), nausea

– lactose intolerance

Giardiasis

• Diagnosis (laboratory)– stool for ova and parasite, repeated x 3 if necessary

– cysts are seen in fixed or fresh stools and occasionally, trophozoites are found in fresh severe diarrhea

– fluorescent antibody and ELISA tests of fecal specimens are available

Giardiasis

• Treatment– metronidazole (Flagyl)

– Alternative drugs

• furazolidone

• paromomycin (humatin)

Giardiasis

• Prevention– education of families, personnel working in daycares,

foodhandlers etc with regards to good hand washing and personal hygiene

– proper removal of human and animal feces

– proper water treatment (soil filtration has been shown to remove cysts) with chlorine and iodine based disinfectant.

Trichomoniasis

• Epidemiology & Etiology– flagellated protozoan parasite found in men & women

at genitourinary site

– makes up 10- 25% of vaginal infection

– often coexists with gonorrhea (40%)

– highest incidence is in women age 16 to 35

– Sexually transmitted disease

– Incubation period is 4-20 days, (average 7 days)

Trichomoniasis

• Signs & Symptoms in Females– symptoms typically begin or worsen at time of

menstrual period

– copious, greenish-yellowish and frothy vaginal discharge with foul odor

– irritation of vulva, perineum and thighs

– dysuria and suprapubic pain, dyspareunia

– in severe cases vaginal walls and surface of cervix may show punctate, red strawberry spots

Trichomoniasis

• Signs & Symptoms Male– infects urethra, prostate and seminal vesicles

– most are asymptomatic

– symptomatic (20%)

– may have transient, white, frothy or purulent urethral discharge

– dysuria

Trichomoniasis

• Diagnosis – detection of motile protozoans in vaginal or urethral

secretions through microscopic examination or by culture

• For both genders a full STD workup should be done

Trichomoniasis

• Treatment– metronidazole

• the single dose is effective in women but has a higher failure rate in men

– all partners must be treated

– if clinical or microbiological resistance to drug then high dose IV or topical administration

Toxoplasmosis

• Epidemiology– infection with the protozoan toxoplasma gondii which

is found worldwide in humans and in many species of animals and birds

– cats are the definitive host as sexual reproduction of T. gondii occurs only in their intestinal tract

– the resultant oocysts are passed in feces and can remain infectious for up to one year in moist soil

Toxoplasmosis

• Human infection results from:– ingestion of cysts from raw or undercooked meat, or

contaminated food and water

– careless handling of cat litter

– from soil by soil-eating children

– transplacental transmission

– from direct innoculation of trophozoites as in blood transfusion

Toxoplasmosis

• Four types:– Primary

• in the immunocompetent patient

– Reactivated

• in the immunocompromised patient

– Congential

– Ocular (Retinochoroditis)

Toxoplasmosis

• Systems affected– nervous

– cardiovascular / pulmonary

– GI

– skin / exocrine

– eyes

Toxoplasmosis

• Signs & Symptoms• Primary in immunocompetent patients

– over 80% of primary infections are asymptomatic

– may resemble infectious mononucleosis

– febrile multisystemic complaints

– non tender lymphadenopathy of the head and neck nodes is the most common symptom

– could have one or multiples of malaise, myalgia, arthralgia, headache and sore throat

Toxoplasmosis

• Reactivated in the immunocompromised – occurs in 30 to 50% of AIDs patients and can occur in

those with cancer or patients who are receiving immunosuppresive drugs

– can develop life-threatening encephalitis or meningioencephalitis

– may present in lungs and eyes and in rare cases in GI tract, heart, skin and liver

Toxoplasmosis

• Congenital Toxoplasmosis– congenital transmission occurs as a result of infection

in a nonimmune woman during pregnancy– up to 1% of pregnancies– severe infections can result in abortions or stillbirths– most dangerous in the early pregnancy– less than 15% however show severe brain or eye

damage at birth, however of all the normal appearing newborns more than 85% will develop symptoms as an adult

Toxoplasmosis

• Ocular/Retinochoroiditis– develops gradually weeks to years after congentital

infection

– focal necrotizing retinitis (yellow or white patches with blurred margins)

– visual defects include blurring and central defects

– pain and photophobia

– may result in glaucoma and blindness

Toxoplasmosis

• Diagnosis– skin test

– antibody levels

– amniocentesis at 20-24 wks in suspected congenital disease

– cysts or trophozoites may be found in blood

– finding tachyzoites confirms acute infection

Toxoplasmosis

• Treatment (Acute)– in immunocompetent hosts asymptomatic infection not

treated unless findings are severe or persistent

– symptomatic - treated until all signs of the illness have subsided (3-4 weeks)

– immunocompromised - treated 4 to 6 weeks post symptoms

Toxoplasmosis

• Treatment (Acute)– pyrimethamine (daraprim) plus sulfadiazine

(microsulfon)

– Folinic acid may be given to counteract the suppression of bone marrow by pyrimethamine

– ocular patients should receive corticosteroids

– Spiramycin for pregnant women

Toxoplasmosis

• Prevention– freezing of meat to –200 C for 2 days or heating meat to

600 C for 4 minutes kills cysts in tissue

– wearing of gloves or using scoop when dealing with cat litter or gardening

– cats should be kept as indoor pets only and fed dry, canned or cooked food only

– ensure thorough washing of hands, utensils and kitchen surfaces etc. after exposure to raw meat

Pneumocystis carinii

• Epidemiology & Etiology– now considered a fungal disease rather than a

protozoan one

– pneumonia arising in immunosuppressed persons caused by Pneumocystis carinii (PCP)

– one of the most common opportunistic infections occurring in patients with HIV infections

– can cause organ involvement & disseminated disease as well as pneumonia


• Signs & Symptoms– abrupt onset

– fever

– tachypnea, shortness of breath

– usually non productive cough

– radiographic findings

– adult patients may present with spontaneous pnuemothorax


• Diagnosis (Laboratory)– serum LDH– positive lung washings– arterial blood gas shows hypoxia– CD4 cell count generally below 200 in HIV infected

patients with PCP– Imaging - chest x-ray shows diffuse bilateral perihilar

infiltrates– Histological demonstration of the organism in sputum

or in bronchoscopy


• Treatment– trimethoprim-sulfamethoxazole (bactrim, septra)

– adjunctive corticosteroid (prednisone or methyl prednisolone) therapy begun within 72 hrs of Dx decreases mortality in AIDS patient (adults & children)

• Prevention– no true means of prevention however prophylaxis is

recommended in the immunocompromised

Outline

• Describe the epidemiology, signs and symptoms, diagnosis, treatment and preventive measures for the following helminthic diseases

– nematodes

– cestodes

– trematodes

Helminthic Disease

• Nematodes (Roundworms)– are nonsegmented cylindrical or spindle shaped worms

ranging from 1mm to almost 1 m in length

– unlike other helminthics, these have have a complete digestive system, including a mouth,body length intestinal tract and an anus

– two kinds: intestinal and tissue

– most have separate, anatomically distinctive sexes

– mode of transmission depends on the species

Nematodes

• Intestinal– Ascariasis

(Roundworm Disease)– Trichuriasis

(Whipworm Disease)– Hookworm Disease– Enterbiasis (Pinworm

Disease– Strongyloidiasis

(Threadworm Disease)

• Tissue– Trichinosis

– Loiasis

– Dracunculiasis

– Onchocerciasis (River Blindness)

– Visceral Larval Migrans

– Filariaisis

Ascariasis

• Epidemiology– caused by ascaris lumbricoles – most common of the intestinal helminths– transmitted by ingestion of soil containing the

organism’s eggs or in fecally contaminated food and drink

– humans are the sole host– larvae grow in the intestine, causing abdominal

symptoms– roundworms may pass to the blood and lungs

Ascariasis

• S&S– larvae in the lung cause capillary and alveolar damage

– low grade fever, non productive cough, blood tinged sputum, wheezing, dyspnea and sub-sternal pain

– adult worms usually produce little, if any, GI symptoms but the passage of a worm in feces may bring the patient in

– heavy infections may produce ulcer like symptoms or intestinal obstruction

Ascariasis

• Diagnosis– microscopic detection of eggs in stools and

occasionally adult worms in stool or vomitus

– during pulmonary phase eosinophils may be elevated as much as 30 to 50% and remain high for about a month

– larvae may be found in sputum

Ascariasis

• Treatment- Albendazole

– Mebendaxole (Vermox)

– Pyrantel Pamoate

– stools must be checked at 2 weeks and patients retreated until all evidence of infestation is gone

Trichuriasis (Whipworm Disease)

• Epidemiology– a nematode infection of the large intestine, usually

asymptomatic, caused by Trichuris trichiura

– passed through ingestion of eggs from contaminated food or after incubation of larvae in 10 to 14 days by fecal oral route

– adult worms embed their heads into the mucosal lining of the cecum or colon


• S&S– light infections often asymptomatic

– heavy infections may have abdominal cramps, diarrhea, distention, flatulence, nausea and vomiting and weight loss

– can lead to rectal prolapse


• Diagnosis– characteristic lemon shaped eggs in stool

– eosinophilia is common in all but light infections

– severe iron deficiency in heavy infection

• Treatment– asymptomatic infections do not require treatment

– for heavier infections can give Albendazole or Mebendazole

Hookworm (Ancylostomiasis)

• Epidemiology– caused by Ancylostoma duodenale and Necator

americanus. Common in 25% of population

– human infection occurs when larvae penetrate the skin, usually in the foot, and pass via lymphatics and bloodstream to the lungs where they enter the alveoli

– they are then carried by ciliary action up the bronchus, trachea and mouth where they are swallowed and attach to the mucosa of the upper small bowel

– worms suck blood at their attachment sites (anemia)


• S&S– ground itch is a characteristic pruritic erythematous

dermatitis, either maculopapular or vesicular

– in pulmonary stage there may be dry cough, wheezing, blood tinged sputum and low grade fever

– in light infestations GI symptoms my be absent with undetectable blood loss


• S&S– in heavy infections wide range from anorexia, diarrhea,

abdominal discomfort and palpitations

– can lead to iron deficiency and hypochromic, microcytic anemia with fatigue, pallor, exertional dyspnea, deformed nails and heart failure


• Diagnosis– thin shelled oval eggs and occult blood in stool– low hemoglobin, serum iron and serum ferritin– eosinophilia and leuckocytosis are present in the pulmonary stage

but not in chronic intestinal phase

• Treatment - Albendazole

– Mebendazole – Pyrantel Pamoate – Levamisole– re-treatment may be necessary at 2 week intervals

Enterobiasis (pinworms)

• Description– intestinal infection with enterobius vermicularis

– transmission is person to person, indirect or auto reinfection

– most common nematode infection and is most often seen in children

– humans are the only host

– multiple infections in families


• S & S– nocturnal perianal itching (characteristic symptom)

– perineal itching/vulvovaginitis

– enuresis

– abdominal pain

– insomnia


• Diagnosis– transparent tape test

– flashlight to perianal region at night for direct observation

– digital rectal examination with saline slide preparation of stool on gloved finger

• Treatment– Mebendazole (vermox)

– Pyrantel pamoate


• Prevention / Avoidance– careful hand washing, keep nail short and clean

– wash anus and genitals at least once a day, preferably in the shower

– don’t scratch anus or put fingers near nose or mouth

– clean bedding, underclothing and night clothes daily preferably after bathing

– vacuum infected house daily for several days after treatment

Strongyloidiasis (Thread Worm)

• Epidemiology– relatively uncommon intestinal nematode

– benign disease in normal individuals but can be fatal in immunocompromised patient

– transmitted by direct skin penetration of larvae found in fecally contaminated soil

– after entering the skin they enter the venous system and travel to the lungs, ascend the trachea to the epiglottis and then descend into the digestive tract


• S&S– transient dermatitis

– cough, rales, sore throat, dyspnea, wheezing and hemoptysis

– abdominal symptoms:

• diarrhea (may alternate with constipation)

• abdominal pain

• flatulence

• anorexia


• Diagnosis– finding eggs and larvae in stool

• Treatment

- Ivermectin– Thiabendazole (mebendazole)

– treatment should continue until all traces of parasite are gone

Nematodes

• Intestinal– Ascariasis

(Roundworm Disease)– Trichuriasis

(Whipworm Disease)– Hookworm Disease– Enterbiasis (Pinworm

Disease– Strongyloidiasis

(Threadworm Disease)

• Tissue– Trichinosis

– Loiasis

– Dracunculiasis

– Onchocerciasis (River Blindness)

– Visceral Larval Migrans

– Filariaisis

Trichinosis (Trichinellosis)

• Epidemiology– caused by Trichinella Spiralis, an intestinal nematode

that encysts in the tissues of human and porcine hosts

– transmitted by eating undercook pork

– in the epithelium of small intestine larvae develop into adults

– female worms then produce larvae which penetrate lymphatics or venules into the bloodstream then become encapsulated in skeletal muscle


• S&S– first week - diarrhea, cramps and nausea

– second week to 2 months – sudden appearance of muscle pain, edema of upper eyelids, fever photophobia, conjunctivitis and myalgia are characteristic signs

– may be followed by subconjunctival, subungual and retinal hemorrhages

– muscles of respiration, speech, mastication and swallowing may be affected


• Diagnosis– Eosinophilia and elevated serum muscle enzymes

– Positive serologic test, muscle biopsy

• Treatment– Intestinal phase

• Abendazole / Mebendazole

– Muscle invasion phase

• severe infections require hospitalization and high doses of corticosteroids

Loiasis

• Epidemiology– chronic filarial diseased caused by Loa loa

– widely distributed in the African Rain Forest

– adult worms can live in subcutaneous tissue for up to 12 years

– transmission is by the deer fly.

– the larvae crawl under the skin and can enter the eye where adult worms are visible in the conjunctival space around the iris

Loiasis

• S&S– characteristic tracks and visible worms under the skin

– transient swellings several centimeters in diameter anywhere on the body (Calabar swellings)

– these swellings are non pitting and nonerythematous and are at times associated with low grade fever, local pain and pruritis

– migration of worms across the eyes may cause pain and intense conjuctivitis

Loiasis

• Diagnosis– detection of microfilariae in blood specimens taking

during daytime (between 10 AM to 4 PM)

• Treatment

- Diethylcarbamazine (DEC)– Albendazole

Dracunculiasis

• Epidemiology– infection of the subcutaneous and deeper tissues by the

large nematode Dracunculus medinensis

– only occurs in humans and is a major source of disability in affected areas

– found in Saudi Arabia, Iran, Central and West Africa, Yemen and the Indian subcontinent

– transmission is by drinking water containing the intermediate hosts copepods, water fleas, in which the larvae live

Dracunculiasis

• Epidemiology– the larvae are liberated in the stomach and cross the

duodenal wall into the viscera and become adults– after mating the male worm dies and the pregnant

female (60-100 cm x 1.7 – 2.0 mm) moves to the surface of the body, where its head reaches the dermis and provokes a blister, which when in contact with water ruptures and the uterus discharges great numbers of larvae

– some worms retract and re-emerge many times and others eventually disintegrate

Dracunculiasis

• S&S– infection may be at several sites

– normally asymptomatic during the 9 to 14 month incubation period except in the last 1-2 weeks when the worm reaches and becomes palpable in the skin

– a blister will develop around the worms anterior end

– several hours before the head appears at the surface, local erythema, burning, pruritis and tenderness develop

Dracunculiasis

• S&S cont’d– systemic allergic reactions such as pruritis, fever

nausea and vomiting,dyspnea, periorbital edema and urticaria may occur 24 hours in advance of head emergence

– after rupture of the ulceration, tissues may become indurated, reddened and tender

– secondary infections such as tetanus are common

– ankle and knee joints infections often result in deformity

Dracunculiasis

• Diagnosis– if not visible on or just below the surface of the skin

then larvae may be seen in smears from discharging skin sinuses

– immersion of area in cold water will stimulate expulsion of larvae

– Eosinophlia is normally present

Dracunculiasis

• Treatment– tetanus immunization

– manual Extraction

– surgical Removal

– following drugs have an anti-inflammatory effect but do not kill the larvae:

• Metronidazole

• Mebendazole

Onchocerciasis (River Blindness)

• Epidemiology– caused by Onchocerca volvulus

– found in Guatemala, southern Mexico, Venezuela, Amazon area and sub Saharan Africa

– transmitted to humans through black fly bites

– a chronic non-fatal filarial disease with fibrous nodules which contain the worms

– adult worms also found in deep seated bundles lying beside the periosteum of bones or near joints


• Epidemiology cont’d– female worm discharges microfilariae that migrate

through the skin often causing an intense pruritic rash, chronic dermatitis, altered pigmentation, edema and atrophy of the skin

– microfilariae often reach the eye, where their invasion and subsequent death causes visual disturbances and blindness


• S&S– pruritic rash

– subcutaneous nodules

– ocular lesions

– pigment changes (usually lower limbs) – often called leopard skin

– loss of skin elasticity and lymphadenitis

– in heavy infections larvae may be seen in urine, blood, tears and sputum


• Diagnosis– Microscopic examination of superficial skin biopsies

– Evidence of larvae in body fluids

– Slit lamp examination

• Treatment– Ivermectin

– surgery

Visceral Larval Migrans(Toxocariasis)

• Epidemiology– due to toxocara canis (dogs) and T. cati (cats)

– a chronic and usually mild disease predominantly in young children but on the increase in adults

– eggs are shed in feces of infected dogs and cats

– direct or indirect transmission from contaminated soil, food and meat

– most common in female dogs and puppies


• S&S– migrating larvae may induce fever, cough,wheezing,

enlarged liver and spleen

– most cases are in children, who present with visual impairment in one eye, leukocoria, squint and loss of red reflex.

• Diagnosis– elevated WBC and eosinophilia

– microscopic evidence of larvae


• Treatment– primarily supportive

– Albendazole/ Mebendazole

– symptoms may persist for months

– usually good outcome but permanent neurological deficits can occur

Filariasis (Elephantiasis)

• Epidemiology– the most frequent cause of this is Wuchereria

bancrofti, Brugia malayi and Brugia Timori

– these filarial worms block the flow of lymph, causing edematous arms, legs and scrotum

– transmission is through the bite of the Anopheles, Aedes and Culex mosquitoes

– humans are the only hosts for Bancrofti and Timori but monkeys and cats may harbour Malayi


• S&S– incubation period can be 8-16 months

– many infections are asymptomatic

– in acute disease:

• fever with or without inflammation of lymphatic nodes which occur at regular intervals and lasts for several days

• in men, as disease progresses may have orchitis and epididymitis


• S&S cont’d– in travellers allergic like findings are common and

include:

• hives, rashes and eosinophlia

– in chronic disease:

• obstruction of lymphatic flow including hydrocele, scrotal lymphedema, lymphatic varices

• elephantiasis of extremities, genitals and breasts


• Diagnosis– microscopic examination of blood or hydrocele fluid

reveals microfilariae

– there is an antigen test for Bancrofti

– Bancrofti are found mostly in nocturnal specimens (10PM – 2AM)


• Treatment– Diethylcarbamazine, albendazole or invermectin

– Mass treatment involving 80 countries continues to be underway to reduce disease and to achieve total eradication by 2020

– albendazole and invermectin are used in Africa and albendazole and diethylcarbamazine are used in all other locations

Nematodes (Roundworms)

• Generalized Precautions and Prevention Methods– adequate sanitation and proper disposal of feces– proper water treatment– uncooked or unwashed vegetables should be avoided in

areas where human feces is used as fertilizer– proper cooking of fish and other marine life– proper handwashing and ensuring good health and

hygiene in foodhandlers– proper follow-up and education to ensure infection is

eradicated and/or prevented

Nematodes (Roundworms)

• Generalized Precautions and Prevention Methods– ensuring pets are properly cared for, immunized and

dewormed and not fed raw or uncooked food

– children’s sandboxes kept covered

– ensure food is properly stored e.g. freezing, not left open

– fly/insect control

Cestodes (tapeworms)

• Description– adult cestodes are long, flat, segmented worms that lack

a digestive tract

• Three parts to a tapeworm– Scolex (head) - functions as a holdfast organ

– Neck - unsegmented region of highly regenerative capacity

– Segments(proglottides) - distal segments are gravid and contain eggs


• Transmission– ingestion of meat, pork or fish that is improperly

cooked or vegetables that have been fertilized with human or animal feces

– autoinfection - hand to mouth

– human to human

– contaminated water

– ingestion of intermediate hosts (fleas, beetles or cockroaches


• Six tapeworms infect humans– Beef tapeworm: Up to 25m in length

– Pork tapeworm: 7m

– Fish tapeworm: 10m

– Dwarf tapeworm: 25-40 mm

– Rodent tapeworm: 20-60 cm

– Dog tapeworm: 10-70 cm


• S & S– large tapeworm infections are generally asymptomatic,

but may have vague gastrointestinal symptoms

– nausea, diarrhea, abdominal pain, fatigue, hunger dizziness

– infection by a beef or pork tapeworm is often discovered by the patient finding segments in stool, clothing or bedding


• Diagnosis– stool evaluation of O & P

– microscopic evaluation of proglottid collected in water or saline

– cellulose tape

– serologic testing

– imaging, Ct and MRI


• Treatment: – Praziquantel – niclosamide

• Prevention– proper cooking of beef, pork, fish– proper freezing of meat or fish– fecal-oral precautions with good hand washing– treatment of infected dogs, and preventing fleas– education

Trematodes (Fluke)

• Trematodes– parasitic flat worm

– depending on the species, infest various organs of the host (intestinal veins, urinary bladder, liver or lung)

– two kinds:

• hermaphrodite - ingested

• sexual flukes – direct penetration though skin

– all use freshwater snails as intermediate host

Trematodes (Fluke)

• Types and Causes of Trematodes:– Schistosomiasis - direct skin penetration or

ingestion

– Fasciolopsiasis – eating uncooked water plants

– Clonorchiasis – eating raw freshwater fish

– Fascioliasis – raw plants (watercress)

– Paragonimiasis – eating raw crab meat

Trematodes (Fluke)

• Schistosmiasis– most important Trematode infection

– snails are intermediate hosts

– two kinds:

• New World – s. mansoni – intestinal

– damage to the intestinal wall is caused by host’s inflammatory response to deposited eggs

– eggs secrete proteolytic enzymes that further damage tissue

Trematodes (Fluke)

• Schistosmiasis• Old world – S. hematobium – urinary

– primary sites of infection are the veins of the urinary bladder

– organism’s eggs can induce fibrosis, granulomas and hematuria

Schistosmiasis

• S & S• Acute phase

– Intestinal

• fever, urticaria, diarrhea (sometimes bloody), malaise, myalgia, weight loss, headache, dry cough, liver and spleen enlargement

– Urinary

• frequency, dysuria, terminal hematuria and proteinuria

Schistosmiasis

• Chronic Intestinal phase– this stage begins 6 months to several years after

infection

– abdominal pain, irregular bowel movements bloody stool, hepato/splenomegaly, hematuria, urethral/bladder pain

– with subsequent slow progression the following may appear: anorexia, weight loss, polypoid intestinal tumors, and features of portal and pulmonary hypertension

Schistosmiasis

• Chronic Urinary – bladder polyp formation, cystitis, chronic salmonella

infection

– pyelitis, pyelonephritis, urolithiasis, hydronephrosis

– bladder cancer has been associated with vesicular schistosomiasis

Trematodes (Fluke)

• Diagnosis– stool examination

– serologic tests (highly sensitive)

– MRI or ultrasonography

• may detect periportal fibrosis & calcified eggs in the liver, the intestinal wall, or the bladder & ureter

– abdominal x-ray

Trematodes (Fluke)

• Treatment– praziquantel

– oxamniquine

• Prevention – proper disposal of feces and urine

– control of snail population through use of molluscides

– scrupulously avoiding contact with contaminated water prevents infection

treat fungal, protozoal and helminthic infections 003.11

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