Table 10.

Numbers of reported cases of laboratory-acquired infections caused by blood and tissue protozoa, by known or likely route of exposurea

Route of exposureNo. of cases of infection with:Total no. (% of 164; % of 125b)
Leishmania spp. (n = 12)Plasmodium spp. (n = 34)Toxoplasma gondii (n = 47)Trypanosoma cruzi (n = 65)Trypanosoma brucei subspp. (n = 6)
Parenteralc 7101411547 (28.7; 37.6)
No available information13839 (23.8; NAi)
Vector-borne transmission19221 (12.8; 16.8)
No accident recognizedd 112720 (12.2; 16.0)
Mucous membrane exposuree 18312 (7.3; 9.6)
Other skin exposure (e.g., via a spill or splash)f
 Nonintact skind,f 1512110 (6.1; 8.0)
 Skin, other1g 1 (0.6; 0.8)
Ingestion (presumptive mode)99 (5.5; 7.2)
Bite (not necessarily the source of infection)h 2114 (2.4; 3.2)
Aerosol transmission?d 11 (0.6; 0.8)
  • a The routes of exposure are listed by descending frequency (see last column). If there was uncertainty about the nature of the exposure (e.g., no accident was recognized) but evidence suggested that one route of transmission was most likely, this route usually was presumed, for the purposes of this table, to have been the mode of transmission. However, the threshold for doing this was subjective because the information available about the cases varied in quantity and quality. Similarly, the distinction between “no accident recognized” and “no available information” was not always clear in the case reports. See text and the tables on the individual parasites for caveats about the various cases.

  • b Percentages are also provided using the number of cases with available data as the denominator. Cases without a recognized accident were kept in the denominator.

  • c Parenteral exposures involved a needle or other sharp object (e.g., glass coverslip, Pasteur pipette, broken capillary hematocrit tube) that punctured, scratched, or grazed the skin.

  • d Some of the laboratorians who did not recall a discrete accident may have had subtle exposures, such as contamination of unrecognized microabrasions or exposure through aerosolization or droplet spread.

  • e With the exception of the case described in footnote g, the exposure was assumed to have been mucosal if the person's face was splashed.

  • f This category includes a hodgepodge of nonparenteral skin exposures. Sometimes the report specified that the person had preexisting skin abrasions, cuts, or breaks (i.e., nonintact skin), whereas other times this was a presumption (e.g., someone who worked barehanded and did not recall parenteral exposures or someone who developed a chagoma at the site of a cuticle was assumed to have had transmission across nonintact skin).

  • g The laboratorian apparently got infected murine blood on his face when a centrifuge tube broke (see the text); whether this represented skin or mucosal contact or transmission by aerosol or droplets is unclear.

  • h All of the case-patients who were bitten by animals are counted here to highlight the importance of this type of injury, even though contamination of the bite wound rather than the bite itself may have been the route of transmission in some of these cases.

  • i NA, not applicable.