The timing, severity of the thrombocytopenia, the occurrence of new thrombosis, and the presence of alternative explanations, all determine the likelihood that HIT is present. A commonly used score to predict the likelihood of HIT is the "4 Ts" score introduced in 2003. A score of 0–8 points is generated; if the score is 0–3, HIT is unlikely. A score of 4–5 indicates intermediate probability, while a score of 6–8 makes it highly likely. Those with a high score may need to be treated with an alternative drug, while more sensitive and specific tests for HIT are performed, while those with a low score can safely continue receiving heparin, as the likelihood that they have HIT is extremely low. In an analysis of the reliability of the 4T score, a low score had a negative predictive value of 0.998, while an intermediate score had a positive predictive value of 0.14 and a high score a positive predictive value of 0.64; intermediate and high scores, therefore, warrant further investigation. The first screening test in someone suspected of having HIT is aimed at detecting antibodies against heparin-PF4 complexes. This may be with a laboratory test of the enzyme-linked immunosorbent assay type. This ELISA test, however, detects all circulating antibodies that bind heparin-PF4 complexes, and may also falsely identify antibodies that do not cause HIT. Therefore, those with a positive ELISA are tested further with a functional assay. This test uses platelets and serum from the patient; the platelets are washed and mixed with serum and heparin.
Once hatched, the larvae then lacerate the skin with their mouthparts, causing open sores. Once the skin has been breached, the larvae then tunnel through the sores into the hosts subcutaneous tissue, causing deep and irritating lesions highly subject to infection. After about the second day, bacterial infection is likely and, if left untreated, causes bacterial bloodstream infections or sepsis. This leads to anorexia and weakness and is generally fatal if untreated. Human vectors
There are three main fly families causing economically important myiasis in livestock and also, occasionally, in humans:
Calliphoridae (blowflies)
Some examples include Calliphora vomitoria and Calliphora vicina
Oestridae (botflies)
Sarcophagidae (fleshflies) Sarcophaga barbata are usually found in dead and rotting meat and animal excrement, which are prime environments for them. This is because their larvae are facultative parasites, as they feed on organic tissue and use the hosts oxygen reserve.Other families occasionally involved are:
Anisopodidae
Piophilidae
Stratiomyidae
Syrphidae

Specific myiasis
Caused by flies that need a host for larval development
Dermatobia hominis (human botfly)
Cordylobia anthropophaga (tumbu fly)
Oestrus ovis (sheep botfly)
Hypoderma spp. (cattle botflies or ox warbles)
Gasterophilus spp. (horse botfly)
Cochliomyia hominivorax (new world screwworm fly)
Chrysomya bezziana (old world screwworm fly)
Auchmeromyia senegalensis (Congo floor maggot)
Cuterebra spp. (rodent and rabbit botfly)

Semispecific myiasis
Caused by flies that usually lay their eggs in decaying animal or vegetable matter, but that can develop in a host if open wounds or sores are present
Lucilia spp. (green-bottle fly)
Cochliomyia spp. (screw-worm fly)
Phormia spp. (black-bottle fly)
Calliphora spp. (blue-bottle fly)
Sarcophaga spp.