Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Example Input: Abstract: To determine the timing of symptoms and oocyst excretion after the acquisition of cryptosporidium infection, we used a screening parasitologic stool examination to identify patients and then contacted them for the collection of retrospective histories and follow-up stool specimens. The study included 68 otherwise healthy patients with an identifiable source and time of infection. All 68 had diarrhea, 61 had abdominal pain, most also had other gastrointestinal symptoms, 33 had fever, and all recovered spontaneously. Among the 50 patients who submitted follow-up stool samples, more than 90 percent of the 610 symptomatic days and of the 136 oocyst-positive stools occurred between days 7 and 28 of infection, the mean incubation period was 7.2 days (range, 1 to 12), and the mean duration of illness was 12.2 days (range, 2 to 26). During the oocyst-excretion period cryptosporidium was detected in 90 percent of Ziehl-Neelsen-stained fecal concentrates. The end of oocyst excretion could be accurately determined in 26 patients; 19 (73 percent) had positive stools after the cessation of symptoms for a mean period of 6.9 days (range, 1 to 15). Fourteen patients were studied for two or more months, and in three of them asymptomatic episodes of oocyst excretion were detected up to two months after clinical recovery. We conclude that many cases of symptomatic cryptosporidiosis occur among immunocompetent patients, some of whom may excrete oocysts even when they have become asymptomatic. Conversely, infected symptomatic patients may occasionally have intermittently negative stools.
Example Output: Timing of symptoms and oocyst excretion in human cryptosporidiosis.

Example Input: Abstract: Magnetic resonance imaging (MRI) is a powerful new tool for the study of human anatomy and pathology. By various MRI techniques, the structure of the middle and inner ears of aborted 20-week fetuses is defined and compared to gross anatomic sections. MRI's potential for evaluating temporal bone development and diseases of the ear is discussed.
Example Output: Magnetic resonance imaging of the fetal temporal bone.

Example Input: Abstract: Nomifensine, an antidepressant used for eight years in Britain, was particularly popular in the north west of England. Haemolytic anaemia was recognised as a rare side effect, but in 1984 a cluster of six cases was referred to the North West Regional Transfusion Centre, reflecting an incidence of 0.006%. These were collected within 18 months and showed variable serological features, indicating that antibodies associated with nomifensine treatment are neither rare nor of one particular type. The accumulation of this and similar data contributed to its withdrawal from the British market in January, 1986.
Example Output:
Immune haemolytic anaemia and nomifensine treatment in north west England 1984-85: report of six cases.