Handling a Centipede

The painful results of a centipede bite have been well known for centuries. In 1740, the English naturalist Charles Owen wrote, "The Scolopendra is a small venomous worm, and amphibious. When it wounds any, there follows a Blueness about the affected Part, and an Itche all over the Body, like that caused by Nettles. Its Weapons of Mischief are much the same as those of the Spider, only much larger; its Bite is very tormenting, and produces not only pruriginous Pain in the Fleshe, but very often Distractions of the Minde."

The venom apparatus consists of modified legs, on either side of the body just behind the head. These are known as maxillipeds, or sometimes as forcipules. The fang itself consists of a hollow tube with a sharp tip, like a hypodermic needle. The venom glands are found inside the body wall at the base of the fangs. When the centipede attacks, muscles surrounding the venom gland squeeze it and force venom through the hollow maxilliped and into the prey's body.

Very little scientific study of centipede venoms has been done, but it is known that some centipede venoms contain the active ingredient 5-hydroxytryptamine. The venom of the North American giant centipede, Scolopendra heros, contains cytolisins which break down cell walls.

Smaller centipedes, such as the orangish Scolopocryptops specimens found under rocks throughout the northeastern United States, produce nothing more than a painful but localized reaction, similar to a bee sting. The larger tropical species found in the pet trade, however, pack more of a punch, and can produce systemic symptoms as well as severe pain at the site of the bite---some people bitten by tropical scolopendromorphs have suffered nausea, vomiting, headaches and swelling in the lymph nodes. The centipede's venom can sometimes have a necrotic effect at the site of the bite, which can produce a painful open sore that takes some time to heal.

There is only one case in the scientific literature of a human death caused by a centipede bite -- a seven year old girl in the Phillipines died after being bitten on the head by a fullgrown tropical centipede, probably the large species Scolopendra subspinipes. Despite the potential danger, however, centipedes are not considered to be a major medical concern in any of the areas where they are found. Nevertheless, be aware that your pet centipede is a venomous animal, and treat it with the respect it deserves. A small percentage of people are allergic to centipede venom, and for these people any bite, no matter how small the pede or how weak the venom, can turn into a life-threatening emergency. If you are allergic to bee stings, the chances are good that you will also experience a reaction to centipede venom.

All of the tropical centipedes should be treated with caution. They should not ever be touched or handled with bare hands. If it is necessary to handle one, to move it to another tank for instance, great care should be exercised. These animals can move very quickly and bite readily, and unlike other animals that move rapidly away from potential danger, centipedes will immediately go on the attack towards any perceived threat.

Smaller centipedes are rather delicate and should be moved carefully. The best method is to place a small container (such as a deli cup) into the tank and then "herd" the centipede into it using an artist's soft-bristled paintbrush. Once the centipede runs inside the container, snap the lid on and it will be safely confined. This method can also be used (with more care) for larger tropical centipedes. To prevent escapes, transfer operations should always be carried out in an enclosed area to prevent the centipede from getting away if it makes a break for it. A bathtub works well (make sure you plug the drain). Keep all of your fingers well out of the way. If you offer a centipede any chance to get a fang into your flesh, it will happily oblige.

Some keepers handle their centipedes using a long pair of tongs or forceps that have been padded at the tips with foam rubber (a method also used to handle scorpions). If the tongs are at least twelve inches in length, the centipede will not be able to reach up and bite you with its fangs. This method should not be used by beginners, however---the exoskeleton of a centipede is not as thick as a scorpion's, and too much pressure can rupture the centipede's body wall and cause death. Centipedes also move very quickly, and it may be very difficult to grasp the pede without causing it to shed a large number of legs. It is far safer for both you and the centipede to prod it into a suitable container using a brush.

It may be best to slow down the centipede somewhat before attempting to move or handle it. This can be accomplished by placing the entire centipede tank in the refrigerator for about fifteen minutes. Centipedes, like all arthropods, are ectotherms and are dependent on their external environment for body heat. The cooler the temperature, the less quickly they are capable of moving. Keep in mind, however, that your centipede is a tropical animal, and cooling it to unnaturally low levels like this will cause it considerable stress. It may also kill the animal if cooled too far or too long. The idea is to cool it enough to slow down its movements, not to immobilize it.

rbc morphology

Acanthocytes are a subgroup of schistocytes consisting of small spherical cells with several finger-like projections from the RBC surface distributed in an irregular manner. The ends of the projections tend to be slightly thickened. Acanthocytes are typically found in large numbers in hereditary abetalipoproteinemia (Bassen-Kornsweig disease, Chapter 22), in moderate numbers in severe liver disease or in anorexia nervosa, and in small numbers in association with schistocytes of other types in other conditions.
Red blood cell crenation (echinocytes) are RBCs that appear normal except for uniform small triangular projections arranged in a uniform manner around the circumference of the cell, like the outer edge of a gearwheel. When most of the RBCs have this appearance, they are most commonly artifactual; but in lesser numbers they may be found in liver disease, renal disease, hyperlipidemia, and in some RBC enzymopathies.
Bite cells (degmacytes) are RBCs with a semicircular defect in one area of the outer edge. When present in significant number, bite cells are suggestive of hemolytic anemia due to an oxidizing agent (Heinz body anemia).
Sickle cells are crescent-shaped RBCs pointed at one or both ends found in some patients with homozygous sickle cell anemia (Chapter 5). Hemoglobin SC disease may sometimes display stubby sickled cells with a short thick bar protruding from the center that represents an Hb C crystal.
Elliptocytes (ovalocytes) are oval RBCs found in varying numbers in persons with congenital elliptocytosis and occasionally in small numbers in normal persons. When seen on edge, the cells may look somewhat like short rods and, rarely, may superficially resemble an atypical sickle cell.
Target cells consist of a peripheral ring and central disk of Hb. Target cells are found in large numbers in Hb C disease (Chapter 5) and in lesser numbers with certain other abnormal hemoglobins, in thalassemia, and in chronic liver disease.
Teardrop cells look like RBCs in which one side has been gently pulled out to a sharp point while the opposite side is still rounded. These cells are most characteristically associated with myeloid metaplasia (myelofibrosis, Chapter 7) but can also be present in lesser numbers in other myeloproliferative syndromes, such as chronic myelocytic leukemia.
Stomatocytes are RBCs that have a rectangular or slit-like central pallor configuration. This may be due to hereditary stomatocytosis or may be drug induced. A few stomatocytes may be found in normal persons and in a variety of diseases.
Rouleaux are RBCs partially adhering to each other with the overall appearance of a partially spread out stack of coins. The RBC central clear area is usually absent. This appearance is similar to that normally seen in the very thick areas of a peripheral blood smear. However, with rouleaux there are a moderate number of free single RBCs intermingled with the RBC stacks, whereas there are no free RBCs in thick areas of the smear. Considerable rouleaux formation suggests the possibility of abnormal serum proteins (such as the monoclonal proteins of multiple myeloma).
Red Blood Cell Inclusions (Fig. 2-1)
Basophilic stippling describes a moderate number of small dark blue dotlike structures scattered fairly uniformly throughout the hemoglobinated area of the RBC. Stippling is derived from nuclear remnants, so that the cell represents a reticulocyte and thus may be seen in many of the same conditions as polychromatophilic RBCs. However, stippling is especially associated with lead poisoning (Chapter 35).





Fig. 2-1 Abnormal RBC. A, normal RBC; B, spherocyte; C, target cell; D, elliptocyte; E, echinocyte; F, sickle cell; G, stomatocyte; H, acanthocyte; I, J, K, L, schistocytes; M, teardrop RBC; N, distorted RBC with Hb C crystal protruding; O, degmacyte; P, basophilic stippling; Q, pappenheimer bodies; R, howell-Jolly body.


Howell-Jolly bodies are small, round, blue-black inclusions that are considerably larger than basophilic stippling and ordinarily occur only one to an RBC. Howell-Jolly bodies may be present in any severe anemia but are more likely to be seen in severe hemolytic anemias and after splenectomy.
Pappenheimer bodies are small dark-staining granular inclusions that tend to occur in small numbers, are irregularly distributed, and often occur in small groups. They actually are hemosiderin granules that can be confirmed with ferricyanide iron stains. They are found after splenectomy, in some patients with sideroblastic anemias, and occasionally in patients with severe hemolytic anemia.
Three types of RBC inclusions cannot be seen with Wright's or Giemsa stain. All three require supravital staining techniques or other special procedures. Reticulocytes (discussed in detail later) are the stage in RBC maturation just before full maturity. Their number serves as an index of bone marrow RBC production. Hemoglobin H inclusions can sometimes be seen on a reticulocyte preparation as uniformly distributed small round dots somewhat resembling basophilic stippling but of slightly differing sizes. If a reticulocyte is affected, the Hb H inclusions coexist with the more irregular and more linear reticulum structures. Heinz bodies also require a special staining procedure and may need RBC pretreatment with a strong oxidizing agent such as phenylhydrazine. Heinz body formation is most often found in anemias due to RBC enzyme defects, "unstable" hemoglobins (Chapter 5), and certain uncommon hemoglobins such as hemoglobin Koln and Zurich. The Heinz bodies are small, scattered, dotlike structures of varying size in the RBC derived from denatured hemoglobin.


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Dr.Hari kumar
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