Page 2044 - Hematology_ Basic Principles and Practice ( PDFDrive )

Chapter 120 Transfusion-Transmitted Diseases 1815

cases occurring in 10 northeast and north central states. Ixodes scapu- that involved a donor developing symptoms 3 days postdonation.
laris, the black-legged tick, transmits B. burgdorferi in those areas, The recipient developed symptoms 6 days posttransfusion.
and Ixodes pacificus, the western black-legged tick, transmits the
infection along the Pacific coast. The ticks feed predominantly in late
spring and early summer during the nymph stage. Emergence has PARASITIC INFECTIONS
been associated with environmental changes that increase deer and
rodent reservoir populations and changing residential patterns putting Malaria
humans in more intimate contact with the tick vectors. Rodents are
the reservoir. Although deer are not infected, they transport and Five Plasmodium species (Plasmodium falciparum, Plasmodium vivax,
maintain the ticks. Birds may also play a role in transporting the Plasmodium ovale, Plasmodium malariae, and Plasmodium knowlesi)
vector ticks. and occasionally others cause the protozoan disease malaria. In 2008
The characteristic erythema chronicum migrans (“bull’s-eye”) rash 243 million cases occurred worldwide, with most in sub-Saharan
is present in 70% to 80% of cases within 30 days of infection. The Africa. Other endemic areas include parts of Asia and South America
wide variety of clinical findings includes malaise, fatigue, headache, and more limited areas in Mexico, Central America, and the Carib-
myalgias, large joint arthralgias and arthritis, and neurologic and bean. Of 1478 imported cases in the United States in 2009, 735 were
cardiac signs and symptoms. These may not immediately suggest acquired in Africa, 142 in Asia/Western Pacific, and 103 in the
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Lyme disease in the absence of a typical rash or known tick exposure. Americas. West Africa accounted for most cases associated with
Serologic testing supports the clinical diagnosis. Unfortunately, poor Africa, and Honduras, Haiti, and Guyana for most of the cases from
specificity is recognized with many screening methods, and a two-step the Americas. During 2009 only two cases were acquired in Mexico,
approach using a sensitive EIA or immunofluorescence assay (IFA) both P. vivax. In 2003 eight autochthonous infections occurred in
followed by a confirmatory, more specific, immunoblot is recom- Palm Beach, Florida; but none subsequently. Vectorial transmission,
mended by the CDC. overwhelmingly the most common route, is by the bite of an infected
B. burgdorferi spirochetemia occurs in 44% of patients with clini- female Anopheles mosquito. Anopheles mosquitoes generally feed
cal Lyme disease and peaks 7 to 10 days after tick bite. The spirochete between dusk and dawn, thereby limiting the risk to tourists who
can survive in red cells, platelets, and frozen plasma for at least the usually visit malaria areas during daylight hours. Almost three-
duration of their routine storage. Transfusion transmission of B. quarters of those who acquired malaria were visiting friends or rela-
burgdorferi has been demonstrated in a murine model. Despite these tives in endemic areas. Missionaries and business travelers represent
observations, no human transfusion-associated cases have been fewer than 20% of infected US citizens. Leisure travelers make up
reported. This may reflect the relatively short spirochetemic phase the small remainder.
and low levels of organisms, as well as deferral of donors with non- P. falciparum accounts for 40% to 46% of US cases detected
specific illness or signs and symptoms of Lyme borreliosis. Although recently, P. vivax 11% to 20%, and P. malariae and P. ovale approxi-
there are no official standards or guidance, it would be prudent for mately 2% each. For the remainder, most are undetermined with a
individuals with a history of Lyme disease to be deferred until well few mixed-species infections. P. knowlesi has not yet been reported.
and treatment has been completed. Seventy percent of imported cases in the United States occur
among returning travelers who were visiting friends or relatives,
ethnically and racially distinct from the majority population of the
Other Tick-Borne Bacteria United States (where malaria is not endemic), who return to their
homelands (countries where malaria is endemic) to visit friends or
The rickettsia that cause human monocytic ehrlichiosis (HME) and relatives. The region of origin is very relevant to measures designed
human granulocytic anaplasmosis (HGA; formerly human granulo- to prevent malaria transmission by transfusion because many of these
cytic ehrlichiosis) are intracellular bacteria that survive in stored individuals are semiimmune and therefore can be parasitemic while
blood. Ehrlichia chaffeensis causes HME and is transmitted to humans asymptomatic. In contrast, donors without malarial immunity who
by Lone Star tick (Amblyomma americanum) bites. Most cases occur travel to endemic areas and become infected are nearly always symp-
in the south central and southeastern United States. Anaplasma tomatic when they are parasitemic and would not be accepted as
phagocytophilum causes HGA and occurs predominantly in the blood donors. Malaria symptoms occurred within 1 month of arrival
northeastern and upper midwestern areas of the United States. I. in the United States in 84% of those infected with P. falciparum and
scapularis and I. pacificus (the Lyme borreliosis vector) transmit the 56% of those with P. vivax in 2009. The latter represents almost all
organism. Signs and symptoms include fever, chills, and headache, cases of relapsing malaria. No acute onsets involving the four most
often associated with thrombocytopenia, leukopenia, and increased frequent Plasmodium species occurred at an interval greater than 1
liver enzyme levels. Intracellular aggregates of microcolonies of bac- year.
teria referred to as morulae appear in monocytes in the HME, and One hundred transfusion cases have been recognized and reported
inclusions appear in granulocytes in HGA. Seroprevalence studies in in the United States since 1963. Since 1999 there have been 19 (0
blood donors in Wisconsin and Connecticut report 0.5% to 3.5% to 3 per year) including one in 2007, none in 2008, two in 2009 and
seropositivity for A. phagocytophilum antibodies. At least nine cases one each in 2010 and 2011; from 2012–2015, no cases have yet to
of transfusion-transmitted HGA from asymptomatic donors have be reported. In the majority of the 100, the case would have been
been recognized after nonleukoreduced RBC transfusion; however, prevented had the extant donor deferral criteria been appropriately
cases have occurred as well following leukoreduction including one applied.
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from apheresis platelets. Both Ehrlichia and Anaplasma spp. are The incubation period for transfusion-associated malaria ranges
white blood cell–associated, and it has been suggested that leukore- from 8 to 90 days. P. falciparum has the shortest time, mean 17 days
duction may mitigate their impact. The infectivity of Orientia tsutsu- (range, 8 to 36 days) and P. malariae the longest, mean 50 days
5
gamushi, the rickettsial agent of scrub typhus, is reduced by up to 10 (range, 8 to 90 days). Most cases involved RBC or whole-blood
by filtration leukoreduction, but infectious E. chaffeensis survived in transfusion, although a few transmissions from platelet transfusions
refrigerated red cells and could be isolated from the packed RBCs have occurred, presumably related to RBC contamination. Transmis-
after filtration. sion from frozen plasma has not been reported.
In a study of heavily tick-exposed military recruits in Arkansas, Current strategies for reducing the low risk for transfusion trans-
which included a look back to 10 blood recipients of units from mission in the United States involve deferral of residents of nonen-
soldiers infected with E. chaffeensis and Rickettsia rickettsii (the agent demic areas who have traveled to malaria-endemic regions during the
of Rocky Mountain spotted fever [RMSF]), no clinical illness previous 12 months, those with residence in endemic areas for 3 years
occurred in recipients. One possible RMSF seroconversion was since their last potential exposure in such regions, and those with a
reported. There is a single case report of transfusion-associated RMSF history of malaria for 3 years after resolution. Apart from incomplete