Expression of circulating leucocytes before, during and after myiasis by Dermatobia hominis in experimentally infected rats.

Expression of circulating white blood cells was investigated in rats (Rattus norvegicus) experimentally infected with larvae of Dermatobia hominis, the human bot fly. Leucocytes were counted prior to infection (control group) as well as at 6, 10, 15, 20 and 28 days post-infection (dpi) and at 7, 15, 30 and 60 days post-larval emergence (dple). Total leucocyte numbers did not differ markedly among the groups. Significant differences were registered when values from control and animals harboring each larval stage of D. hominis were compared; with crescent rank: L1-, L2-, control and L3-infected groups. Leucocyte numbers were significantly higher in the control, 15, 20 or 28 dpi groups than in the 6 dpi animals. Higher counts were observed in control, L2- or L3-infected rats than L1-infected animals. Neutrophils, eosinophils and both large and small lymphocytes were also counted and analyzed. Basophils and monocytes were insufficient in number to permit statistical studies. These results stimulate the continuity of the studies about the host-parasite relationship in the dermatobiosis.

Expression of circulating leucocytes before, during and after myiasis by Dermatobia hominis in experimentally infected rats

Expression of circulating white blood cells was investigated in rats (Rattus norvegicus) experimentally infected with larvae of Dermatobia hominis, the human bot fly. Leucocytes were counted prior to infection (control group) as well as at 6, 10, 15, 20 and 28 days post-infection (dpi) and at 7, 15, 30 and 60 days post-larval emergence (dple). Total leucocyte numbers did not differ markedly among the groups. Significant differences were registered when values from control and animals harboring each larval stage of D. hominis were compared; with crescent rank: L1-, L2-, control and L3-infected groups. Leucocyte numbers were significantly higher in the control, 15, 20 or 28 dpi groups than in the 6 dpi animals. Higher counts were observed in control, L2- or L3-infected rats than L1-infected animals. Neutrophils, eosinophils and both large and small lymphocytes were also counted and analyzed. Basophils and monocytes were insufficient in number to permit statistical studies. These results stimulate the continuity of the studies about the host-parasite relationship in the dermatobiosis.

A expressão de leucócitos sangüínea foi investigada em ratos (Rattus norvegicus) experimentalmente infectados com larvas de Dermatobia hominis. As células foram contadas antes, durante, aos 6, 10, 15, 20 e 28 dias pós-infestação (dpi), e aos 7, 15, 30 e 60 dias pós-emergência das larvas dos hospedeiros. O total de leucócitos não apresentou marcante diferença entre todos os grupos de animais. Todavia, diferenças significantes foram observadas quanto ao parasitismo pelos estádios larvares, com nível crescente: L1, L2, controle e L3. Na comparação entre grupos: o número de leucócitos foi significativo pró-controle, -15, -20 ou -28 dpi do que aos 6 dpi; e pró-controle, -L2 ou -L3 do que para L1. Neutrófilos, eosinófilos e linfócitos (pequenos e grandes) foram também analisados. Em contraste, o número insuficiente de basófilos e monócitos não permitiram estudos estatísticos. Estes resultados estimulam a continuação dos estudos sobre a relação parasito-hospedeiro nas dermatobioses.

Activated host neutrophils in the larval midgut lumen of the human bot fly Dermatobia hominis.

Light microscopy (LM) and transmission electron microscopy (TEM) were used to observe activated polymorphonuclear neutrophils from mammalian hosts as well as invading bacteria in the midgut lumen of larvae of the human bot fly Dermatobia hominis. Other resident or recruited cells associated with dermal myiasis were fed on by larvae and digested more rapidly than neutrophils. The latter were observed moving towards bacteria and particles of food, extending the filopodia and engulfing material to be digested within phagosomes. The larval midgut lumen, thus, appears to be a suitable environment to produce neutrophil activation at least for short periods, as seen in mammalian hosts. Although interactions between phagocytes and bacteria in the midgut lumen may be important in bot fly larval development, further studies are required to confirm this.