DTIC ADA555429: Medical Surveillance Monthly Report (MSMR). Volume 19, Number 1, January 2012

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JANUARY 2012
Volume 19
Number 1 M E D I C A L S U RV E I L L A N C E M O N T H LY R E P O RT
Malaria Issue
PAGE 2 Update: Malaria, U.S. Armed Forces, 2011
PAGE 7 Sources of variability of estimates of malaria case counts, active and
reserve components, U.S. Armed Forces
WRAIR, Entomology Branch
LTC Jason H. Richardson
PAGE 11 Images in health surveillance: Malaria vectors and malaria testing
PAGE 12 Editorial: Malaria in the U.S. Armed Forces: A persistent but preventable
threat
Mark M. Fukuda, MD
PAGE 14 Historical snapshot: Development of the hepatitis A vaccine
CDC
SUMMARY TABLES AND FIGURES
PAGE 16 Deployment-related conditions of special surveillance interest
CDC/Dr. Mae Melvin

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Update: Malaria, U.S. Armed Forces, 2011
METHODS
U.S. service members are at risk of malaria when they are assigned to endemic
areas (e.g., Korea), participate in operations in endemic areas (e.g., Afghani- Th e surveillance period was January
stan, Africa) and visit malarious areas during personal travel. In 2011, 124 2003 through December 2011. Th e sur-
service members were reported with malaria. Nearly three-fourths of cases veillance population included active and
were presumably acquired in Afghanistan (n=91) and one-fi ft h were consid- reserve component members of the U.S.
Armed Forces. Th e Defense Medical Sur-
ered acquired in Africa (n=24). One-quarter of cases were caused by P. vivax
veillance System was searched to identify
and one-fi ft h by P. falciparum (including 6 Afghanistan-acquired infections);
reportable medical events and hospitaliza-
most cases were reported as “unspecifi ed” malaria. Malaria was diagnosed/
tions (in military and non-military facili-
reported from 51 diff erent medical facilities in the United States, Afghan-
ties) that included diagnoses of malaria
istan, Kyrgyzstan, Iraq, Germany and Korea. Providers of care to military
(International Classifi cation of Diseases,
members should be knowledgeable regarding and vigilant for clinical presen-
Ninth Revision, Clinical Modifi cation
tations of malaria outside of endemic areas.
[ICD-9-CM] code: 084). A case of malaria
was defi ned as an individual with (1) a
reportable medical event record of con-
fi rmed malaria; (2) a hospitalization record
malaria is a serious, oft en life- endemic areas (e.g., Afghanistan,7 Africa,8 with a primary (fi rst-listed) diagnosis of
threatening, mosquito-trans- Haiti9); and when they visit malarious malaria; (3) a hospitalization record with
mitted parasitic disease. Four areas during personal travel. Th e U.S. a non-primary diagnosis of malaria due
Plasmodium species are responsible for the military has eff ective countermeasures to a specifi c Plasmodium species (ICD-
overwhelming majority of human malaria against malaria, including chemopro- 9-CM: 084.0-084.3); (4) a hospitalization
infections: Plasmodium falciparum (the phylactic drugs, permethrin-impregnated record with a non-primary diagnosis of
most deadly), P. vivax (the most common), uniforms and bed nets, and DEET-con- malaria plus a diagnosis of anemia (ICD-
P. ovale, and P. malariae. Th ree other Plas- taining insect repellents. When cases and 9-CM: 280-285), thrombocytopenia and
modium species that infect non-human outbreaks of malaria do occur, they are
primates have been found to occasionally generally due to non-compliance with
cause malaria in humans. P. knowlesi, in indicated chemoprophylactic or personal FIGURE 1. Malaria cases among U.S.
particular, has been responsible for many protective measures. service members, by Plasmodium species
cases in Malaysia and occasional cases else- In the 1990s, there was a general and calendar year of diagnosis/report,
2003-2011
where in southeast Asia, but its contribu- increase in malaria incidence among
tion to the worldwide burden of malaria U.S. service members, primarily due to P. Unspecified
has been minor. vivax infections acquired near the DMZ 180 OOtthheerr PPllaassmmooddiuiumm
Malaria is endemic in more than 100 in Korea.5,6, 10-12 Since 2001, U.S. service
PP.. ffaallcciippaarruumm
countries throughout the tropics and in members have been exposed to malaria 160
PP.. vviivvaaxx
some temperate regions. In 2011, malaria risk due to P. vivax while serving in
140
accounted for 216 million illnesses and an Southwest and Central Asia (particularly
estimated 655,000 deaths worldwide; most in Afghanistan).7 Service members who
120
deaths were due to P. falciparum infections conduct civil-military and crisis response
s
of young children in Africa.1 International operations in Africa are at risk of malaria e 100
s
a
eff orts to control malaria are working; due to P. falciparum;8 the number at risk c
of 80
many countries have reported reductions may have increased since the establish- o.
N
in the numbers of malaria cases and deaths ment of the U.S. Africa Command (AFRI- 60
due to malaria during the past decade.2 COM) in 2007. In 2010, several thousand
For centuries, malaria has been recog- U.S. military members risked exposure to 40
nized as a disease of military operational P. falciparum while conducting an earth-
20
signifi cance.3,4 U.S. service members are at quake disaster response mission in Haiti.9
risk of malaria when they are permanently Th is report summarizes the malaria 0
assigned to endemic areas (such as near the experiences of U.S. service members dur- 03 04 05 06 07 08 09 10 11
0 0 0 0 0 0 0 0 0
Demilitarized Zone [DMZ] in Korea);5,6 ing calendar year 2011 and compares it to 2 2 2 2 2 2 2 2 2
when they participate in operations in recent experience. Year
Page 2 MSMR Vol. 19 No.1 January 2012
related conditions (ICD-9-CM: 287), or
malaria complicating pregnancy (ICD- TABLE 1. Malaria cases by Plasmodium species and selected demographic
9-CM: 647.4) in any diagnostic position; characteristics, U.S. Armed Forces, 2011
or (5) a hospitalization record with a non-
primary diagnosis of malaria plus diagno- P. vivax P. falciparum Unspecifi ed or Total Percentage
other total
ses of signs or symptoms consistent with
Total 36 28 60 124 100.0
malaria (as listed in the Control of Com-
Component
municable Diseases Manual, 18th Edition)
Active 31 25 52 108 87.1
in each diagnostic position antecedent to Reserve/Guard 5 3 8 16 12.9
malaria. Malaria diagnoses during out- Service
patient encounters alone (i.e., not hospi- Army 30 19 50 99 79.8
talized or reported as a notifi able event) Navy 2 2 3 7 5.6
were not considered case-defi ning for this Air Force 1 1 4 6 4.8
analysis. Marine Corps 3 6 3 12 9.7
Gender
Th is summary allowed one episode
Male 35 28 58 121 97.6
of malaria per service member per 365-
Female 1 0 2 3 2.4
day period. When multiple records doc-
Age group
umented a single episode, the date of the
<20 0 1 0 1 0.8
earliest encounter was considered the date
20-24 12 7 25 44 35.5
of clinical onset, and the most specifi c diag- 25-29 13 7 14 34 27.4
nosis was used to classify the Plasmodium 30-34 3 4 8 15 12.1
species. 35-39 5 5 6 16 12.9
Presumed locations of malaria acqui- 40+ 3 4 7 14 11.3
sition were estimated using a hierarchical Race/ethnicity
classifi cation algorithm: (1) cases hospi- White, non-Hispanic 25 15 49 89 71.8
talized in a malarious country were con- Black, non-Hispanic 4 11 2 17 13.7
Other 7 2 9 18 14.5
sidered acquired in that country; (2)
case reports (submitted as reportable
FIGURE 2. Malaria infections by medical events) that listed exposures to responsible agent was “unspecifi ed” for 46
Plasmodium species and presumed location malaria endemic locations were consid- percent (n=57) of 2011 cases.
of acquisition, U.S. Armed Forces, 2011 ered acquired in those locations; (3) cases In 2011, as in prior years, most U.S.
diagnosed among service members dur- military members diagnosed with malaria
100
ing or within 30 days of deployment or were male (98%), active component mem-
Unspecified
assignment to a malarious country were bers (87%), in the Army (80%), of “white”
90
OOtthheerr PPllaassmmooddiiuumm considered acquired in that country; (4) race/ethnicity (72%) and in their 20s (63%)
80 PP.. ffaallcciippaarruumm cases diagnosed among service members (Table 1).
70 PP.. vviivvaaxx who had been deployed to Afghanistan or Of the 124 malaria cases in 2011,
Korea within two years prior to diagnosis nearly three-quarters of the infections
es 60 were considered acquired in those coun- were considered to have been acquired
s
a tries; (5) all remaining cases were consid- in Afghanistan (n=91, 73%) and approxi-
c
of 50 ered acquired in unknown locations. mately one-fi ft h in Africa (n=24, 19%);
o.
N 40 only four infections (3%) were presumably
acquired in Korea (Table 2). Th e remaining
30 RESULTS fi ve malaria cases (4%) had unknown areas
of infection acquisition. Th e number of
20
In 2011, 124 U.S. military members infections considered acquired in Afghani-
10 were diagnosed and/or reported with stan in 2011 was the highest of the nine-
malaria. Th e number of malaria cases in year period. Of the 24 malaria infections
0
n a a n 2011 was the third highest of the previous considered acquired in Africa, 16 were
a c e w
ghanist Afri Kor Unkno onfi n2e0 1y1e acrass e(Fs iwguerree c1a).u Msedor bey t hPa. nfa locnipea-rfi uft mh l7i;k eClya maecrqouoinre: d5 , inS ieWrrae sLt eAonfrei:c a2 , (NGihgaenriaa:
Af (n=28, 23%) and more than one-quar- and Senegal: 1 each); four were considered
ter by P. vivax (n=36, 29%) (Table 1). Th e acquired in East Africa (Uganda: 2; Kenya
January 2012 Vol. 19 No. 1 MSMR Page 3
TABLE 2. Number of malaria cases by geographical location of diagnosis or report and presumed location of acquisition, U.S.
Armed Forces, 2011
PPrreessuummeedd llooccaattiioonn ooff aaccqquuiissiittiioonn
Location of diagnosis/report
Korea Afghanistan Africa Unknown Total cases % of total
Fort Campbell, KY 1 22 0 0 23 18.5
Jalalabad, Afghanistan 0 12 0 0 12 9.7
Fort Stewart, GA 0 4 1 1 6 4.8
Camp Lejeune, NC 0 2 4 0 6 4.8
Portsmouth, VA 0 5 1 0 6 4.8
Fort Bragg, NC 1 3 1 0 5 4.0
Camp Salerno, Afghanistan 0 5 0 0 5 4.0
Landstuhl, Germany 0 0 4 0 4 3.2
Bagram/Camp Lacy, Afghanistan 0 3 0 0 3 2.4
Fort Wainwright, AK 0 2 0 0 2 1.6
Camp Pendleton, CA 0 2 0 0 2 1.6
Fort Shafter, HI 0 2 0 0 2 1.6
Fort Sill, OK 0 0 2 0 2 1.6
Fort Bliss, TX 0 2 0 0 2 1.6
New York 0 2 0 0 2 1.6
North Carolina 0 1 0 1 2 1.6
Eastern Texas 0 2 0 0 2 1.6
Sharan, Afghanistan 0 2 0 0 2 1.6
Kandahar, Afghanistan 0 2 0 0 2 1.6
Other locations 2 18 11 3 34 27.4
Total (% total) 4 (3.2%) 91 (73.4%) 24 (19.4 %) 5 (4.0%) 124 100.0
and Madagascar: 1 each); two were consid- P. falciparum, 34 (37%) by P. vivax, 1 (1%) During 2011, malaria cases were diag-
ered acquired in the Horn of Africa (Ethio- by P. malariae and 50 (55%) were diag- nosed/reported from 51 diff erent medical
pia, Djibouti); one in Central Africa (Chad) nosed or reported as “unspecifi ed” malaria facilities in the United States, Afghanistan,
and 1 was reported only as “Africa” (data (Figure 2). Th e vast majority (83%) of cases Kyrgyzstan, Iraq, Germany and Korea.
not shown). likely acquired in Africa were caused by More than one-quarter of cases (n=34,
Of the 91 Afghanistan-acquired P. falciparum and all four Korea-acquired 27%) were reported from or diagnosed
malaria infections, 6 (7%) were caused by infections were of “unspecifi ed” type. outside the United States (Table 2). Twenty-
four cases were reported from U.S. military
facilities in Afghanistan (Figure 3) and 7
FIGURE 3. Plasmodium vivax malaria transmission in Afghanistana and locations from
cases were reported from/treated in U.S.
which malaria cases among U.S. service members were reported in 2011
facilities in Germany. Brian Allgood Army
Community Hospital in Seoul, Korea, the
376th Expeditionary Medical Support in
Manas, Kyrgyzstan and an unnamed medi-
cal facility in Bagdad treated one case each
(data not shown). Of note, more than 18
BBaaggrraamm percent of all malaria cases during the year
were treated at/reported from Fort Camp-
JJaallaallaabbaadd
bell, KY (n=23) (Table 2).
In 2011, 90 of 124 malaria cases
CCaammpp SSaalleerrnnoo
SShhaarraann among U.S. military members were diag-
nosed from June through October; there
was more distinct seasonality in 2011 than
KKaannddaahhaarr in recent prior years (Figure 4). Th e fi nd-
No P. vivax transmission ing refl ects the relatively higher number
Low P. vivax transmission and proportion of cases acquired in tem-
High P. vivax transmission perate Afghanistan as compared to tropical
regions of Africa and Haiti.
aGuerra CA, Howes RE, Patil AP, et al. The international limits and population at risk of Plasmodium vivax transmission
in 2009. PLoS Negl Trop Dis. 2010 Aug 3; 4(8):e774.
Page 4 MSMR Vol. 19 No.1 January 2012
FIGURE 4. Malaria among U.S. service members, by estimated location of infection acquisition, 2003-2011
60
Other location
Liberia Africa
peacekeeping
Afghanistan
50 mission,
August 2003 Korea
40
s Afghanistan:
e
s Operation
ca Mountain Thrust, Benin
of 30 May-July 2006 humanitarian
No. eJuxelyr c2i0s0e9, Haiti
earthquake
response
20 Jan-May
2010
10
0
Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct
2003 2004 2005 2006 2007 2008 2009 2010 2011
Afghanistan may have contributed to this Personal travel to malaria-endemic coun-
EDITORIAL COMMENT
year’s increase; in 2011, malaria cases were tries was not accounted for unless specifi ed
reported from fi ve locations in Afghanistan in a notifi able event report. Persons born in
In 2011, the total number of cases of
as compared to just one (Bagram) in 2010. malaria-endemic regions have been found
malaria diagnosed/reported among U.S.
Annual changes in environmental vari- to be over-represented among the cases of
military members was higher than in the
ables may also aff ect malaria acquisition; malaria in U.S. service members. A recent
previous four years and seven of the previ-
in Afghanistan, irrigation and temperature report estimated that the malaria rate was
ous nine years. Th e data illustrate continu-
(but not precipitation) are the strongest 44 times higher in service members born in
ing acquisition of malaria from Africa and
predictors of malaria transmission.13 western Africa than among those born in
Afghanistan. Th ere were more Afghani-
Th ere are signifi cant limitations to the United States.14
stan-acquired malaria infections in 2011
the report that should be considered when As in prior years, in 2011, most malaria
than in any of the prior eight years. Of
interpreting the fi ndings. For example, the cases among U.S. military members were
note, there were six Afghanistan-acquired
ascertainment of malaria cases is likely treated at medical facilities remote from
infections caused by P. falciparum, while
no more than three such infections were incomplete; some cases treated in deployed malaria endemic areas; of note, more than
reported in any of the prior nine years. or non-U.S. military medical facilities may 50 medical facilities treated any cases, and
Malaria acquisition from Korea remained not have been reported or otherwise ascer- 31 facilities treated only one case each dur-
relatively low; since 2008, compared to tained. Only malaria infections that resulted ing the past year. Providers of acute medical
prior years, there have been remarkably in hospitalizations in fi xed facilities or were care to service members (in both garrison
fewer Korea-acquired cases among U.S. reported as notifi able medical events were and deployed settings) should be knowl-
military members. considered cases for this report; infections edgeable of and vigilant for the early clini-
Numerous factors could contribute to that were treated only in outpatient settings cal manifestations of malaria – particularly
year-to-year changes in numbers of malaria and not reported as notifi able events were among service members who are currently
cases. Th e number of service members not included as cases. Also, the locations or were recently in malaria-endemic areas
deployed in malaria-endemic countries is of infection acquisition were estimated (e.g., Afghanistan, Africa, Korea).
not constant; a surge of 30,000 new troops from reported relevant information. Some Care providers should be capable
arrived in Afghanistan in December 2010. cases had reported exposures in multiple of diagnosing malaria (or have access to
Improved capacity for malaria diagnosis malarious areas, and four percent of cases a clinical laboratory that is profi cient in
and case reporting by military personnel in had no relevant exposure information. malaria diagnosis) and initiating treatment
January 2012 Vol. 19 No. 1 MSMR Page 5
(particularly when falciparum malaria is int/mediacentre/factsheets/fs094/en/index.html. U.S. Marines deployed to Liberia. Am J Trop
clinically suspected). Continued emphasis 2. World Health Organization. World Malaria Med Hyg. 2010 Aug;83(2):258-65.
Report 2010. Available at: http://www.who.int/ 9. Armed Forces Health Surveillance Cen-
of standard malaria prevention protocols
malaria/world_malaria_report_2010/en/. ter. Malaria among deployers to Haiti, U.S.
is warranted; all military members at risk 3. Ognibene AJ, Barrett, O. Malaria: Introduction Armed Forces, 13 January-30 June 2010.
of malaria should be informed in detail of and background, In: Internal medicine in Medical Surveillance Monthly Report (MSMR).
the nature and severity of the risk; they Vietnam (vol II): General medicine and infectious 2010;17(8):11.
diseases. Ed: Ognibene AJ, Barrett O. Offi ce of 10. Han ET, Lee DH, Park KD, et al. Reemerging
should be trained, equipped, and supplied
the Surgeon General, Center of Military History, vivax malaria: changing patterns of annual
to conduct all indicated countermeasures; U.S. Army, Washington, D.C., 1982:271-8. incidence and control programs in the Republic of
and they should be closely monitored 4. Shanks GD, Karwacki JJ. Malaria as a Korea. Korean J Parasitol. 2006 Dec;44(4):285-
to ensure compliance. Personal protec- military factor in Southeast Asia. Mil Med.1991; 94.
156(12):684-6. 11. Chol PT, Suwannapong N, Howteerakul N.
tive measures against malaria include the
5. Lee JS, Lee WJ, Cho SH, Ree H. Outbreak Evaluation of a malaria control project in DPR
proper wear of permethrin impregnated of vivax malaria in areas adjacent to the Korea, 2001-2003. Southeast Asian J Trop Med
uniforms; the use of bed nets and military- demilitarized zone, South Korea, 1998. Am J Public Health. 2005 May;36(3):565-71.
issued DEET-containing insect repellent; Trop Med Hyg. 2002;66(1):13-7. 12. Ciminera P, Brundage J. Malaria in U.S.
6. Armed Forces Health Surveillance Center military forces: a description of deployment
and compliance with prescribed chemo-
(Provisional). Korea-acquired malaria, U.S. exposures from 2003 through 2005. Am J Trop
prophylactic drugs before, during, and
Armed Forces, January 1998-October 2007. Med Hyg. 2007 Feb;76(2):275-9.
aft er times of exposure in malarious areas. Medical Surveillance Monthly Report (MSMR). 13. Adimi F, Soebiyanto RP, Najibullah S, Kiang
2007;14(8):2-5. R. Towards malaria risk prediction in Afghanistan
7. Kotwal RS, Wenzel RB, Sterling RA, et al. using remove sensing. Malar J. 2010 May
An outbreak of malaria in US Army Rangers 13;9:125.
REFERENCES
returning from Afghanistan. JAMA. 2005 Jan12; 14. Wertheimer ER, Brundage JF, Fukuda MM.
293(2):212-6. High rates of malaria among US military members
1. World Health Organization. Malaria Fact Sheet 8. Whitman TJ, Coyne PE, Magill AJ, et al. An born in malaria-endemic countries, 2002-2010.
N°94. Dec 2011. Available at: http://www.who. outbreak of Plasmodium falciparum malaria in Emerg Infect Dis. 2011 Sep;17(9):1701-3.
Page 6 MSMR Vol. 19 No.1 January 2012
Sources of Variability of Estimates of Malaria Case Counts, Active and Reserve
Components, U.S. Armed Forces
e.g., the clinical settings from which diag-
noses are reported, diff erentiation between
Each January, the Medical Surveillance Monthly Report (MSMR) estimates
relapsing/recurrent single cases and repeat
numbers of malaria infections among U.S. service members using a surveil-
new cases (“incidence” rules), and sources
lance case defi nition to identify “malaria cases”. Th ese cases include indi-
of case-fi nding information.
viduals with a hospital discharge diagnosis of malaria and those who were
reported with malaria through military notifi able event reporting systems.
Th is report compares the MSMR surveillance case defi nition with other pro- METHODS
posed case defi nitions to demonstrate the degree to which estimates of num-
Th e surveillance period was January
bers of malaria cases are dependent upon clinical settings, data sources and
2009-December 2010. Th e surveillance
case-defi ning rules used to produce such estimates. For example, including
population included all individuals who
outpatient diagnoses as malaria cases would more than double the 2010 case
served in an active or reserve component
count. As compared with cases defi ned using other proposed case defi ni-
of the U.S. Army, Navy, Air Force, Marine
tions, many more MSMR-defi ned cases had records of a specifi c Plasmodium Corps or Coast Guard at any time during
species, a laboratory test for malaria and recent travel to a malaria-endemic the surveillance period.
country. Interpretations of the results of MSMR reports should consider how Service members with diagnoses spe-
“cases” are defi ned. cifi c to malaria were identifi ed from stan-
dardized records routinely transmitted to
the Armed Forces Health Surveillance Cen-
ter. Th ese records included notifi able event
reports from service-specifi c reporting sys-
each January, the MSMR reports of the cases would be “false positive” cases tems; records of inpatient and outpatient
numbers of malaria infections (e.g., clinically suspected but subsequently encounters in fi xed U.S. military facilities
among U.S. service members dur- ruled out). For example, if a malaria diag- (excludes care provided in Iraq/Afghani-
ing the preceding nine years. Th e com- nosis reported only on an outpatient record stan) and some non-military facilities (i.e.,
pleteness and accuracy of malaria case qualifi ed as a malaria “case”, the number purchased care); records of medical care
count estimates depend on specifi cations of malaria cases reported in the MSMR provided to service members deployed
of the “surveillance case defi nition” that each year would markedly increase. How- to Operations Iraqi Freedom/Enduring
is used to identify cases. For the MSMR’s ever, the MSMR’s surveillance case defi ni- Freedom/New Dawn (primarily in Iraq
annual malaria summary, a case of malaria tion does not consider outpatient malaria or Afghanistan) and reported to the Th e-
is defi ned as a U.S. military member who diagnoses alone as case defi ning events for ater Medical Data Store (TMDS); records
received a discharge diagnosis of malaria surveillance purposes. Such diagnoses are of all aeromedical evacuations (MEDE-
on an electronic record of a hospitaliza- believed to include provisional (“rule out”) VACs) conducted by the U.S. Transporta-
tion or was reported as a case of malaria diagnoses of malaria or miscoded docu- tion Command; and records of laboratory
through a military notifi able medical event mentation of heath care encounters for tests (Health Level 7 [HL7] records) con-
reporting system (see page 3). Individuals malaria chemoprophylaxis, the provision ducted in U.S. military medical treatment
can be counted as incident malaria cases of malaria prevention counseling, and so facilities.
only once during any 365-day period. on. For this report, three diff erent surveil-
By design, the MSMR case defi nition is a Clearly, interpretations of results lance case defi nitions were used to identify
specifi c – but not particularly sensitive reported each year in the MSMR should “malaria cases” (Table 1). Th e case defi -
– surveillance case defi nition; that is, it is consider how “cases” of malaria are defi ned. nitions used for the analysis were hier-
designed to increase the likelihood that To help in this regard, this report assesses archical; that is, each case defi nition was
each malaria case enumerated in the report the variability of estimates of case counts of mutually exclusive of the others.
is a “true case.” malaria in relation to characteristics of sur- MSMR cases: Th e MSMR case defi -
Use of a less restrictive case defi nition veillance case defi nitions. In particular, the nition is that used to identify cases for the
would increase the number of “malaria report demonstrates the degree to which annual malaria report (described on page
cases” identifi ed for surveillance purposes; estimates of malaria case counts are depen- 3-4). Briefl y, MSMR cases were defi ned by
it is likely, however, that relatively more dent upon case defi nition components, i) notifi able medical event reports in which
January 2012 Vol. 19 No. 1 MSMR Page 7
TABLE 1. Defi nitions of malaria “case” types
Malaria “case” type Surveillance case defi nition
MSMR-defi ned case A notifi able medical event report (reported to a military event reporting system) in which the malaria diagnosis
is “confi rmed”; a hospitalization in a fi xed medical facility with a primary (fi rst-listed) diagnosis of malaria;
hospitalization with a non-primary diagnosis of a malaria due to a specifi c Plasmodium species; or a non-
primary diagnosis of malaria preceded by diagnoses of selected signs, symptoms or conditions consistent
with malaria (complete defi nition on p. 3).
“Possible” case: Not a case above and
Other malaria hospitalizations/ (a) Hospitalization in a fi xed medical facility with a non-primary diagnosis of malaria; or
notifi able events, multiple outpatient (b) Hospitalization in Iraq/Afghanistan with a malaria diagnosis in any diagnostic position; or
diagnoses (c) Two or more outpatient primary (fi rst-listed) diagnoses of malaria within 14 days; or
(d) Notifi able event for which the malaria diagnosis is not “confi rmed”.
“Unlikely” case: Not a case above and
single outpatient diagnoses (a) Single outpatient primary (fi rst-listed) diagnosis of malaria
malaria diagnoses were “confi rmed”; or ii) repeat (“new”) cases. For example, an indi- any case type. Th irty-fi ve percent (n=190)
records of hospitalizations in fi xed (e.g., vidual with two separate hospitalizations of the cases were classifi ed as MSMR-
not deployed, at sea) medical facilities for malaria may be counted as one case or defi ned; “possible” and “unlikely” cases
with a primary (fi rst-listed) diagnosis of two cases, depending on the length of time comprised approximately 14 percent
malaria; or iii) hospitalization record with between the two hospitalizations. To assess (n=77) and 52 percent (n=283) of the total,
a non-primary diagnosis of a malaria due the eff ects of various incidence rules on respectively (Table 2).
to a specifi c Plasmodium species; or iv) estimates of case counts, for this analysis, Of all MSMR-defi ned cases in 2009
hospitalization record of a non-primary aff ected service members were not eligible (n=71) and 2010 (n=119), approximately
diagnosis of malaria preceded by diagnosis for consideration as new cases for 60, 180 two-thirds (n=123, 65%) were documented
of a sign, symptom or condition consistent or 365 days aft er each malaria case-defi n- with hospitalization records; the remainder
with malaria. ing event. were reports of confi rmed malaria diagno-
Possible cases: Th e “possible case” To further assess diff erences in the ses as notifi able medical events (Table 2).
defi nition identifi ed cases that were not malaria-specifi c information related to the Of the possible cases in 2009 (n=42)
MSMR-defi ned cases. Possible cases were three case-defi nition types, prevalences and 2010 (n=35), two-thirds were docu-
defi ned by i) records of hospitalizations of documentation of three characteristics mented with records of two or more out-
with malaria-specifi c diagnoses in second thought to be indicative of “true cases” of patient encounters within 14 days with
or subsequent diagnostic positions (with malaria were assessed: (1) report of a diag- primary diagnoses of malaria (Table 2). Of
no malaria-specifi c or associated diagno- nosis of a specifi c Plasmodium species; (2) the others, 8 cases were hospitalized in
ses in the primary diagnostic position); record of a malaria-specifi c laboratory test; U.S. military facilities in Iraq/Afghanistan;
ii) records of malaria-related hospitaliza- and (3) evidence that aff ected service mem- 4 cases had non-primary (not fi rst-listed)
tions in medical facilities in Iraq/Afghani- bers had recently deployed to, served in or diagnoses of malaria on records of hos-
stan; iii) notifi able medical event reports in received medical care in a malaria-endemic pitalizations in fi xed U.S. military medi-
which “malaria” diagnoses were reported country. Th ese characteristics were cal facilities; and 14 cases (including 10
as non-confi rmed; or iv) records of at least assessed using electronic medical, person- among Navy or Marine Corps members)
two outpatient encounters within 14 days nel and deployment records. Of note, such were reports of “unconfi rmed” diagnoses
with malaria-specifi c primary diagnoses. records do not capture personal travel dur- of malaria as reportable medical events.
Unlikely cases: Th e “unlikely case” defi - ing leave. Laboratory records were assessed By defi nition, unlikely cases in 2009
nition identifi ed cases that were not MSMR only for cases diagnosed in 2010. (n=142) and 2010 (n=141) were docu-
cases or possible cases. Unlikely cases were mented with records of single outpatient
defi ned by single outpatient encounters visits with primary diagnoses of malaria.
with malaria-specifi c primary diagnoses RESULTS
(Table 1). Number of cases, by source of data
For surveillance purposes, “inci- Number of cases, by surveillance case defi nition
dence rules” are used to diff erentiate single If “possible” and “unlikely” cases
cases (which may have multiple associ- During the two-year surveillance were used to estimate numbers of malaria
ated medical encounters/reports) from period, there were 550 malaria “cases” of cases, annual estimates would be 3.5 and
Page 8 MSMR Vol. 19 No.1 January 2012
FIGURE 2. Numbers and proportions
TABLE 2. Numbers of malaria “cases” identifi ed using 3 different surveillance case of malaria “cases” with and without a
defi nitions, and characteristics of those cases, U.S. Armed Forces, 2009-2010 Plasmodium-specifi c diagnoses, by malaria
“case” type, 2009-2010
MSMR-defi ned Possible Unlikely
Total no. of cases (2009-2010) 190 77 283
Unspecified malaria
Clinical setting
Hospitalization 123 12 -- PPPlllaaasssmmmooodddiiiuuummm ssspppeeeccciiieeesss
Notifi able event 67 14 -- 100%
Outpatient visit -- 51 283
Other malaria-specifi c information
80%
Malaria species diagnosed/reporteda 103 15 38 87
Patient traveled to malarious countryb 154 53 112
al
Laboratory test ordered (2010 only) 59 15 11 ot60% 62
Laboratory test positive (2010 only) 20 0 0 of t 245
%
Incidence rule (length of ineligibility to be counted as a new case)
40%
365 days 190 77 --
180 days 190 78 -- 103
60 days 195 78 -- 20%
aDiagnosis of ICD-9-CM codes 084.0-084.3 (P. falciparum, P. vivax, P. malariae, P. ovale) 15 38
bNotifi able event reported from, or hospitalization, deployment or military service in, a malaria-endemic country 0%
during the 12 months prior to (and including) the incident malaria diagnosis MSMR cases Possible cases Unlikely cases
(n=190) (n=77) (n=283)
FIGURE 1. MSMR-defi ned malaria cases 2.5 times the current MSMR estimates for events, the total numbers of each case defi -
and other potential malaria “cases” by data 2009 and 2010, respectively (Figure 1). For nition type increase by 0 to 1 and 1 to 5,
source and year, 2009-2010 example, if hospitalized cases in U.S. mil- respectively (Table 2).
itary facilities in Iraq/Afghanistan in 2010
"Unconfirmed" notifiable events
were added to MSMR cases (n=119), the Documentation of other malaria-specifi c
Hospitalizations, deployed (TMDS) estimated number of cases would be 125. information
If outpatient cases in deployed and fi xed
Outpatient visits, deployed (TMDS)
facilities were also included, the estimated A specifi c diagnosis of P. falciparum
Outpatient visits, in fixed facilities of malaria cases in 2010 would be 281. Of or P. vivax was available for the majority of
MMSSMMRR ccaasseess (hospitalizations, note, inclusion of MEDEVAC records of MSMR-defi ned cases (n=103, 54%), one-
confirmed notifiable events) malaria diagnoses would add no cases to fi ft h of “possible” cases (n=15, 20%), and
the estimate; all 18 service members with 13 percent (n=38) of “unlikely” cases (Table
300
12 a malaria-related MEDEVAC in 2009 or 2, Figure 2).
6 2010 were also diagnosed with malaria in Of the 190 MSMR-defi ned cases, 154
2 other clinical settings. (81%) had documented temporal-geo-
250 2
graphic exposures to malaria risk, i.e.,
75
Variation in relation to the “no risk” period deployment to, or military service, travel or
88 after case defi ning events (“incidence rule”) hospitalization in, a malaria-endemic coun-
200
try during the 12 months prior to a malaria
es" Th ere were small changes in total diagnosis/report. Of the “possible” and
cas 150 81 numbers of cases detected by each surveil- “unlikely” cases reported from fi xed medical
of " lance defi nition in relation to the lengths of facilities (and not from Iraq/Afghanistan),
No. 90 “ineligibility” periods aft er case-defi ning the proportions with evidence of potential
100 events (“incidence rule”). When aff ected “exposure” to malaria were 69 percent and
individuals are not eligible to be counted 40 percent, respectively (Table 2).
as new malaria cases for 365 days aft er Of 2010 cases reported from fi xed
119
50 case-defi ning events, the numbers of cases medical facilities, a malaria-specifi c lab-
71 of each surveillance defi nition type are as oratory test was ordered for one-half of
reported above. When periods of ineligibil- MSMR-defi ned cases, 58 percent of “pos-
0 ity to be counted as new cases are reduced sible cases” and 15 percent of unlikely cases
2009 2010
to 180 days and 60 days aft er case-defi ning (Table 2). A positive malaria diagnostic
January 2012 Vol. 19 No. 1 MSMR Page 9