Download Parasitic Infections Malaria Malaria is considered the world`s most

Parasitic Infections
Malaria

Malaria is considered the world's most important parasitic disease,
responsible for an estimated 300 to 500 million cases and annual deaths in
excess of 1 million.1

The distribution of the four Plasmodium species of malaria varies worldwide,
with Plasmodium falciparum, which has the highest mortality,

Malaria transmission in the United States has occurred from the blood of
immigrants and rarely through blood transfusions .Malaria can also be
transmitted congenitally and through contaminated needles.

The characteristic malarial paroxysms of chills and fever in patients usually
coincide with the periodic release of merozoites and other pyrogens in the
blood.

In P. falciparum infections, this periodicity may not always be apparent.
However, intervals of 48 hours between paroxysms are reported for
Plasmodium vivax, Plasmodium ovale, and P. falciparum (tertian
periodicity), and 72 hours for Plasmodium malariae (quartan periodicity).

Unlike infections caused by P. falciparum and P. malariae, infections with P.
vivax and P. ovale have a latent form of the exoerythrocytic phase that can
persist in the host liver for months to years. This latent form can produce
relapses of the erythrocytic infection

Most fatal cases of imported malaria in the United States are the result of
travelers' failure to comply with appropriate chemosuppressive regimens,
delays in seeking treatment, misdiagnosis by physicians or laboratories, and
inappropriate antimalarial regimens.2,13 Prophylactic drug regimens for
individuals traveling to endemic areas are problematic
Acute Malaria
Signs and Symptoms

Abdominal examination reveals a soft, tender spleen that is slightly enlarged.

↓Blood pressure (BP); pulse 120 beats/minute, respiration rate 32
breaths/minute, and temperature 40°C.

Laboratory findings include hemoglobin (Hgb) 11 g/dL (normal, 12–16);
hematocrit (Hct) 34% (normal, 36%–47%);↓ white blood cell (WBC) count
with 76% neutrophils (normal, 45%–65%), 23% lymphocytes (normal, 15%–
35%), and 1% monocytes (normal, 1%–6%); platelets 83 × 103/mm3 (normal,
150–450); and bilirubin 1.0 mg/dL (normal, 0.1–1).

Urinalysis reveals trace amounts of albumin and the presence of
urobilinogen.
Treatment
Quinidine and Quinine
Start on intravenous (IV) quinidine gluconate.4,9,11,18,27 For doses of IV quinidine, see
Table 74-1. If >48 hours of parenteral therapy is required, the dosage of quinidine
should be reduced by one-third to one-half.
Oral quinine and clindamycin or the combination of atovaquone and proguanil
(Malarone) can be used until IV quinidine is available.
While receiving the IV quinidine, M.L.'s electrocardiogram, BP, and serum glucose
should be monitored closely.4,7,9 Supportive care, including fluid, IV dextrose 5% to
10% and electrolyte management, dialysis, blood transfusion, and mechanically
assisted ventilation, are important adjunctive therapies in seriously ill patients. The
serum concentration of quinidine should be determined once daily during the
continuous infusion.
Managing Chloroquine-Resistant Plasmodium falciparumCRPF
One of the recommended drug treatments for CRPF infection, which is added to
quinine therapy, is doxycycline 100 mg twice daily for 7 days (doxycycline should
overlap the quinine for 2 to 3 days before the latter is discontinued) or clindamycin
900 mg three times a day for 5 days.27 If the patient cannot tolerate oral doxycycline,
IV doxycycline 100 mg Q 12 hr can be substituted. An alternative in a patient who
can tolerate oral therapy and in whom it is not contraindicated (i.e., history of
seizures, or endemic area where P. falciparum is not resistant to the agent)
mefloquine 750 mg can be initiated, followed by 500 mg 12 hours later.
Managing Other Plasmodia Species
A patient infected with one of the other species of Plasmodia (P. vivax, P. ovale, or P.
malariae) should receive oral chloroquine phosphate (Aralen). The initial dose is 1 g
(600 mg base) followed by 500 mg (300 mg base) 6 hours later; subsequently, 500
mg (300 mg base) is administered daily for 2 days.27 For patients who cannot tolerate
the oral doses of chloroquine, parenteral doses of quinidine can be administered
(Question 2 lists doses).27 Patients with P. ovale and P. vivax also should be given
primaquine to prevent relapses from the latent exoerythrocytic stages in the liver.
The adult dosage of primaquine is 52.6 mg/day (30 mg base) for 14 days; this should
follow the chloroquine regimen.
Chemoprophylaxis and Pregnancy
All travelers to endemic areas should receive chemoprophylaxis for malaria.
Pregnant women are at greater risk for malaria infection and its complications
(especially severe hemolytic anemia and splenomegaly) and should be advised not to
travel to areas endemic for malaria
Chloroquine and Primaquine Phosphate
Chloroquine phosphate is an effective chemoprophylactic agent against all species of
Plasmodia except drug-resistant P. falciparum. The adult dosage of chloroquine
phosphate is 500 mg (300 mg base) once weekly beginning 1 week before departure
and continuing for 4 weeks after last exposure. The pediatric dosage of chloroquine is
5 mg/kg base (8.3 mg chloroquine phosphate) once weekly beginning 1 week before
departure and continuing for 4 weeks after exposure. A suspension of chloroquine in
chocolate syrup can be prepared for children (5 mg/mL). Chloroquine prophylaxis is
safe during pregnancy, and the benefits outweigh the risk of malaria and the drug's
possible side effects.9,11,13,27,29,31 Mefloquine and Malarone may be options for
prophylaxis and treatment in pregnancy29,30,31,32,33,34; however, these are not
recommended for this particular indication in the United States.27
By taking the chloroquine 1 week before travel, the patient can achieve adequate
antimalarial chloroquine levels in the blood by the second week. Potential side effects
also can be detected early. A weekly dose of 0.5 g of chloroquine phosphate produces
average plasma concentrations of chloroquine between 0.47 and 0.78 mcmol/L Most
strains of P. vivax and P. falciparum are susceptible to plasma levels between 0.046
and 0.093 mcmol/L, respectively.7,18,35 Mefloquine (Lariam) 250 mg (salt) once
weekly beginning 1 week before departure and continuing for 4 weeks after leaving a
malarious area is an alternative regimen to chloroquine.7,18,27,36 Mefloquine is not
recommended during pregnancy or in children weighing ≤5 kg, however, because the
safety of this agent has not been fully established in these populations.27 Recently, P.
vivax was reported to be resistant to chloroquine in Indonesia and New Guinea, and
despite the lack of data on mefloquine in pregnancy (T.R. is in the second trimester),
T.R. may have to be given this agent.15,18,32,33,37,38 Chloroquine suppresses the asexual
erythrocytic forms of the malaria parasite and has no action against the
exoerythrocytic phase of P. vivax and P. ovale.7,18 However, primaquine phosphate
prevents relapses of P. vivax and P. ovale by inhibiting the exoerythrocytic stage; it
also has a significant gametocidal effect against all species.11,15,18 To prevent an attack
after departure from an area where P. vivax and P. ovale are present, the clinician
should also prescribe primaquine phosphate 52.6 mg/day (30 mg base) for 14 days to
coincide with the last 2 weeks of the chloroquine regimen. Primaquine should not be
administered to pregnant patients.27 The major toxicity of concern, aside from the
teratogenic risk, is hemolytic anemia in patients with RBC glucose-6-phosphate
dehydrogenase (G6PD) deficiency7,18,28,36,39
Prophylaxis for Chloroquine-Resistant Plasmodium falciparum
Prophylaxis for CRPF also can be achieved by taking mefloquine in the doses
indicated above instead of using the
chloroquine regimen.27 An alternative to mefloquine is doxycycline 100 mg/day
beginning 1 day before travel and continuing for the duration of the stay and for 4
weeks after leaving the malarial area
An alternative to the mefloquine chemoprophylaxis regimen in CRPF areas is the
combination of atovaquone 250 mg and proguanil 100 mg (Malarone) administered
once daily taken 1 to 2 days before departure and continued for 1 week after
return.1,2,27 The pediatric dosage (Malarone Pediatric) contains 62.5 mg of
atovaquone and 25 mg of proguanil.
Pyrimethamine has teratogenic effects and sulfonamides are contraindicated in early
pregnancy; however, chloroquine, quinine, and quinidine have been suggested as
safe treatments during pregnancy.2,4,27,29,32,33,39,43 Although not associated with
abortions, low birthweight, neurologic retardation, or congenital malformations,
mefloquine is associated with an increased risk of stillbirth.
Malaria Vaccine
At present, three types of vaccines against P. falciparum are under study: a merozoite
vaccine that would induce immunity against the erythrocytic forms of plasmodia in
the blood, a sporozoite vaccine that would protect against the exoerythrocytic or liver
phase, and a gamete vaccine (“transmission blocking”) that would prevent
transmission of malaria in endemic areas.49 When a vaccine for malaria is available, it
is expected to provide an immune response for at least 1 year. The safety of these
vaccines to the fetus and mother during pregnancy will require evaluation.
Multidrug-Resistant Plasmodium Falciparum Malaria
Chemoprophylaxis against malaria in this region of southeast Asia has become
progressively difficult because of the appearance of P. falciparum strains resistant to
chloroquine, pyrimethamine-sulfadoxine, quinine, and even mefloquine.
F.S. will have to take chemoprophylaxis against both P. vivax and multidrug-resistant
P. falciparum. Mefloquine (Lariam) 250 mg once weekly starting 1 week before travel
and continuing weekly for the duration of the stay and for 4 weeks after leaving
Thailand is recommended.27 On return from his visit, primaquine phosphate should
be added to F.S.'s regimen to prevent an attack of P. vivax, because mefloquine has
no effect on the exoerythrocytic phase of P. vivax (see Question 3 for doses of
primaquine).27 Another alternative drug for prophylaxis against P. falciparum malaria
for F.S. would be doxycycline 100 mg taken once daily beginning 1 to 2 days before
departure and continuing for 4 weeks after he returns from Thailand.
Side Effects of Antimalarials
The major side effects of chloroquine (e.g., nausea, abdominal pain, pruritus, vertigo,
headache, and visual disturbances
Abdominal cramps associated with primaquine may be relieved by antacids or by
taking the drug after meals.
Glucose-6-Phosphate Dehydrogenase Deficiency
Primaquine sensitivity, or G6PD deficiency, is an inherited error of metabolism
transmitted by a gene of partial dominance located on the X chromosome. Patients
with this enzyme deficiency are sensitive to the 8-aminoquinolines, sulfonamides,
para-aminosalicylates, nitrofurantoin, sulfone, aspirin, quinine, quinidine, nalidixic
acid, and methylene blue.
Hemolysis reportedly occurs on the third day of drug ingestion and usually is
manifested as abdominal discomfort, anemia, and hemoglobinuria
Drug Therapy of Parasitic Infection
Drug of Choice
Amebiasis
(Including Cyst
Passers)
Asymptomatic
Iodoquinol
or
Diloxanide furoate
or
Paromomycin
Mild to Moderate
Gastrointestinal
Disease
Metronidazole or
Tinidazole
followed by
Iodoquinol
Severe
Gastrointestinal
Dosage
Adverse Effects
Adults: 650 mg PO TID × 20 days Rash, acne, thyroid
enlargement
Children: 30–40 mg/kg/days PO
TID × 20 days
Adults: 500 mg PO TID × 10 days Flatulence, abdominal pain
Children: 20 mg/kg/day PO TID ×
10 days
Adults: 25–35 mg/kg/day PO TID × Nausea, vomiting
7 days
Children: Same as adults
Adults: 750 mg PO TID × 10 days
Children: 35–50 mg/kg/day PO
TID × 10 days
Adults: 2 g once daily × 3 days
Nausea, headache, metallic
taste, disulfiram reaction
with alcohol, paresthesia
Metallic or bitter taste,
anorexia, nausea,
vomiting, epigastric
discomfort, weakness,
seizures, peripheral
neuropathy
Children: 50 mg/kg (max. 2 g) × 3
days
Adults: 650 mg PO TID × 20 days Rash, acne, thyroid
enlargement
Children: 30–40 mg/kg/day PO
TID × 20 days
Disease
Metronidazole or
Tinidazole
followed by
Iodoquinol
Alternatives
Dehydroemetine
followed by
Iodoquinol
Amebic Liver
Abscess
Metronidazole or
Tinidazole
followed by
Iodoquinol or
Alternatives
Dehydroemetine
followed by
Adults: 750 mg PO TID × 10 days
Children: 35–50 mg/kg/day PO
TID × 10 days
Adults : 2 g once daily × 5 days
Nausea, headache, metallic
taste, disulfiram reaction
with alcohol, paresthesia
Metallic taste or bitter
taste, nausea, vomiting,
epigastric discomfort,
anorexia and weakness
Children : 50 mg/kg/day (max. 2 g)
× 5 days
Adults: 650 mg PO TID × 20 days Rash, acne, thyroid
enlargement
Children: 30–40 mg/kg/day PO
TID × 20 days
Adults: 1–1.5 mg/kg/day IM × 5
days (max. 90 mg/day)
Arrhythmias, hypotension;
ECG: P-R, Q-T, QRS
prolongation, S-T
depression
Children: Same as adults
Adults: 650 mg PO TID × 20 days Rash, acne, thyroid
enlargement
Children: 35–40 mg/kg/day PO
TID × 20 days
Adults: 750 mg PO TID × 10 days Nausea, headache, metallic
taste, disulfiram reaction
with alcohol, paresthesia
Children: 35–50 mg/kg/day PO
TID × 10 days
Adults : 2 g once daily × 5 days
Children : 50 mg/kg (max. 2 g) × 5
days
Adults: 650 mg PO TID × 20 days Rash, acne, thyroid
enlargement
Children: 30–40 mg/kg/day PO
TID × 20 days
Adults: 1–1.5 mg/kg/d IM × 5 days Arrhythmias, hypotension;
(max. 90 mg/day)
ECG: P-R, Q-T, QRS
prolongation, S-T
depression
Children: Same as adult
Diloxanide furoate or Adults: 500 mg PO TID × 10 days
Children: 20 mg/kg/day PO TID ×
10 days
Paromomycin
Adults: 25–30 mg/kg/day PO TID × Nausea, vomiting
7 days
Children: Same as adults
Ascariasis
(Roundworm)
Albendazole
or
Mebendazole
Enterobiasis
(Pinworm)
Mebendazole
Adults/Pediatric: 400 mg once
Nausea and headache
Adults and children: 100 mg BID
PO × 3 days
Diarrhea, abdominal pain
Adults and children: 100 mg once;
repeat in 2 wk
Pyrantel pamoate or Adults and children: 11 mg/kg PO
once (max. 1 g), repeat in 2 wk
Albendazole
Adult/Pediatric: 400 mg once;
Repeat in 2 wk
Diarrhea, abdominal pain
Nausea, headache,
dizziness, rash, fever
Abdominal pain, reversible
alopecia, increased
transaminases, rarely
leukopenia
Filariasis
Diethylcarbamazine Adults: Day 1, 50 mg PO; day 2, 50 Severe allergic/febrile
mg TID; day 3, 100 mg TID; days reactions, gastrointestinal
4–14, 6 mg/kg/day in 3 doses
disturbance, rarely
encephalopathy
Children: Day 1, 25–50 mg; day 2,
25–50 mg TID; day 3, 50–100 mg
TID; days 4–14, 6 mg/kg/day in 3
doses
Flukes
(Trematodes)a
Praziquantel
Adults and children: 75 mg/kg/day Malaise, headache,
in 3 doses × 1 day (exceptions: C. dizziness, sedation, fever,
sinensis and P. westermani, × 2
eosinophilia
days)
Giardiasis
Metronidazole or
Adults: 250 mg PO TID with meals Nausea, headache, metallic
× 5 days
taste, disulfiram reaction
with alcohol, paresthesia
Children: 15 mg/kg/day PO TID ×
5 days
Quinacrineb
Adult: 100 mg PO TID × 5 days
Gastrointestinal yellow
staining of skin and
psychosis
Pediatric: 2 mg/kg TID × 5 days
(max 300 mg/day)
c
Nitazoxanide
Pediatric: 12–47 mo
Abdominal pain, diarrhea,
vomiting and headache
100 mg (5 mL) Q 12 hr × 3 days 4–
11 yr
200 mg (10 mL) Q 12 hr × 3 days
Hookworm
Mebendazole
Adults and children: 100 mg PO
Diarrhea, abdominal pain
BID × 3 days
Lice
1% Permethrin (NIX) Topical administration
or
Occasional allergic
reaction, mild stinging,
erythema
Ivermectin
Adults and Children : 200 mcg/kg × Fever, pruritus, sore lymph
3, day 1, day 2 and day 10
nodes, headache, joint
pains, rarely hypotension
Leishmaniasis
Sodium
stibogluconate or
Liposomal
Amphotericin B
Adult: 20 mg SB/kg IV or IM × 20– Gastrointestinal, malaise,
28 days Pediatric: Same as adult headache arthralgias,
myalgias, anemia,
neutropenia,
thrombocytopenia; ECG
abnormalities (ST- and Twave changes)
Adult: 3 mg/kg/day (days 1–5) and Hypotension, chills,
3 mg/kg/days 14 and 21 Pediatric: headache, anemia,
Same as adult
thrombocytopenia, fever,
and elevated serum
creatinine
===============
=============
============
Malaria
All Plasmodia Except
ChloroquineResistant
Parenteral therapy
Quinidine gluconate Adults: Loading dose 10 mg/kg of ECG: Q-T and QRS
salt (6.2 mg base) diluted in 250 mL prolongation; hypotension,
normal saline and infused IV over 2 syncope, arrhythmias;
hr, followed by a continuous IV
cinchonism
infusion of 0.02 mg/kg/min (0.012
mg base) for 72 hr; switch to oral
quinine 650 mg Q 8 hr as soon as
possible
Pediatric: Same as adult
Oral therapy
Chloroquine
Adult: 1 g (600 mg base), then 500 Gastrointestinal, headache,
Phosphate
mg 6 hr later, then 500 mg at 24 and pruritus, malaise, and
48 hr later.
cinchonism
Pediatric: 10 mg base (max. 600
mg base) then 5 mg base/kg 6 hr
later, then 5 mg/base at 24 and 48 hr
Chemoprophylaxis
Chloroquine
Adult: 500 mg (base) once weekly Dose-related: vertigo,
phosphate
(beginning 1–2 wk before departure nausea, dizziness, lightand continuing through stay and up headedness, headache,
to 4 wk after returning)
visual disturbances, toxic
psychosis and seizures
Pediatric: 5 mg/kg base once
weekly up to adult dose (300 mg
base)
Chloroquine
Resistant Therapy
(CRF)
Mefloquine or
Atovaquone/
proguanil
Adult: 750 mg followed by 500 mg Nausea, vomiting,
12 hr later
abdominal pain,
arthralgias, chills,
dizziness, tinnitus and A-V
block
Pediatric: 15 mg/kg followed 8–12
hr later by 10 mg/kg
Adult: 2 tablets BID × 3 days
Rash, nausea, diarrhea,
increased
aminotransferases,
cholestasis
Pediatric: 11– 20 kg: 1 adult
tablet/d × 3 days 21–30 kg: 2 adult
tablets/day × 3 days 31–40 kg: 3
adult tablets/day × 3 days >40 kg: 2
adult tablets BID × 3 days
ChemoprophylaxisCRF
Mefloquine or
Adult: 250 mg once weekly
beginning 1–2 wk before departure,
continuing through stay and for 1–4
wk after return
Pediatric: <15 kg: 5 mg/kg once
weekly 15–19 kg: 1/4 tablet once
weekly 20–30 kg: 1/2 tablet once
weekly 31–45 kg: 3/4 tablet once
weekly >45 kg: 1 tablet once
weekly
Doxycycline
Adult: 100 mg daily beginning 1–2 Nausea, diarrhea and
days before departure continuing monilial rash
during stay and 1 wk after return
Quinine sulfate
Adults: 650 PO TID × 3 days
Cinchonism
plus
Children: 25 mg/kg/day PO TID ×
3 days
PyrimethamineAdults: 3 tablets at once (withhold Gastrointestinal, erythema
sulfadoxine
until febrile episode)
multiforme, Stevens(Fansidar) or
Johnson syndrome, toxic
epidermal necrolysis
Children: 1/2–2 tablets (depends on
age)c
Mefloquine
Adults: 1,250 mg once
Dose-related: vertigo,
nausea, dizziness, lightheadedness, headache,
visual disturbances, toxic
psychosis seizures
Children: 25 mg/kg once (>45 kg)
Prevention of
Relapses (P. vivax
and P. ovale)
Primaquine
phosphate
============
Scabies
5% Permethrin
(Elimite cream)
Alternatives
Ivermectin
Lindane (Kwell)
Crotamiton 10%
(Eurax)
Tapewormd
Praziquantel
Hydatid Cystse
Albendazole
Adults: 52.6 mg/day (30 mg base) × Abdominal cramps,
14 days; this follows chloroquine or nausea, hemolytic anemia
mefloquine regimen
in G6PD
==============
=============
Topical administration
Rash, edema, erythema
Adults: 200 mcg/kg PO; repeat in 2 Nausea, diarrhea, dizziness
wk
vertigo and pruritus
Apply topically once
Not recommended in
pregnant women, infants,
and patients with
massively excoriated skin
Topically
Local skin irritation
Adults and children: 5–10 mg/kg
PO × 1 dose
Malaise, headache,
dizziness, sedation,
eosinophilia, fever
Adults: 400 mg BID × 8–30 days,
repeat if necessary
Diarrhea, abdominal pain,
rarely hepatotoxicity,
leukopenia
Children: 15 mg/kg/day × 28 days,
repeat if necessary (surgical
resection may precede drug
therapy)
Trichomoniasis
Metronidazole
Adults: 2 g PO × 1 day or 250 mg
PO TID × 7 days
Nausea, headache, metallic
taste, disulfiram reaction
with alcohol, paresthesia
Children: 15 mg/kg/day PO TID ×
7 days
a
Schistosoma haematobium, S. mansoni, S. japonicum, Clonorchis sinensis,
Paragonimus westermani.
b
Quinacrine is available in the United States: Panorama Compounding Pharmacy,
Van Nuys, CA 91406.
c
Same dose is recommended in children with Cryptosporidium parvum.
d
Diphyllobothrium latum (fish), Taenia solium (pork), and Dipylidium caninum
(dog), except for Hymenolepis nana where the dose is 25 mg/kg × 1dose.
e
Echinococcus granulosus, E. multilocularis. For neurocysticercosis: 400 mg BID 8–
30 days.
BID, twice daily; ECG, electrocardiograph; G6PD, glucose-6-phosphate
dehydrogenase; IM, intramuscularly; PO, orally; TID, three times daily.
Amebiasis
Giardiasis
Enterobiasis
Cestodiasis
Pediculosis Pediculosis
Prevalence
Pediculosis (lice infections) can be caused by head lice (Pediculus humanus capitis)
(Fig. 74-10), body lice (P. humanus), or crab lice (Phthirus pubis). Lice infections can
be present in all socioeconomic groups, but are seen more often among the poor
because of crowded living conditions and infrequent washing.
The most common complaint of patients with head and body lice is pruritus of the scalp,
ears, neck, and other body parts. With severe infestations, as seen in D.J., intractable itching
and scratching can result in folliculitis, hemorrhagic macules or papules, postinflammatory
skin thickening, and pigmentation.112,113,114,115,116 In contrast, schoolchildren who are exposed
frequently to head lice may have only minor pruritus affecting the scalp, ears, and neck.11
Scabies