zoonoses and communicable diseases common to ... - PAHO/WHO

154 BACTERIOSESIt is difficult to demonstrate that armadillos are a source of infection for manbecause of the long incubation period and the impossibility of excluding a humansource in an endemic area. In Texas, a case of human leprosy was attributed to apatient’s practice of capturing armadillos and eating their meat (Freiberger andFudenberg, 1981). Subsequently, another five cases with hand lesions were detectedin natives of the same state who habitually hunted and cleaned armadillos but hadno known contact with leprosy patients (Lumpkin III et al., 1983). To determine ifthere was a significant association between contact with armadillos and human leprosyin Louisiana, a group of 19 patients was compared with another group of 19healthy individuals from the same area. Of those with leprosy, four had had contactwith armadillos, as opposed to five in the control group. Consequently, it was concludedthat such an association did not exist (Filice et al., 1977). However, this conclusionwas questioned, since the only valid comparison would be between personswho have handled armadillos and those who have had no contact with them(Lumpkin III et al., 1983).The prevalence of leprosy in armadillos in Louisiana and Texas suggests thatthese animals could serve as a reservoir of M. leprae. However, nothing is knownabout the frequency of infection in nonhuman primates and the role they may playin transmission of the disease. The sources of the cases of leprosy in these animalswere probably people with lepromatous leprosy.Diagnosis: Clinically, an anesthetic or hypoesthetic cutaneous lesion raises suspicionof leprosy, even more so if the nerves are enlarged. Diagnosis is confirmed bybiopsy of the skin lesion, which also permits classification of the form of the leprosy.For patients with lepromatous or borderline lepromatous leprosy, diagnosis can bemade by using the Ziehl-Neelsen staining technique on a film of nasal mucosa scrapingsor the interphase between erythrocytes and leukocytes from a centrifuged bloodsample. Histopathologic preparations do not stain well using Ziehl-Neelsen and consequentlya Fite-Faraco stain is recommended. Also used is the simplified stainingmethod consisting of eliminating acid-fastness with pyridine in order to differentiateM. leprae (Convit and Pinardi, 1972). In tuberculoid and other paucibacillary formsof leprosy, it is difficult and at times impossible to confirm the presence of the etiologicagent; in any case, examination of many histologic sections is recommended inorder to detect any bacteria present, especially in the nerve endings.Skin tests have no diagnostic value, but they do serve as an aid to prognosis.Patients with tuberculoid leprosy or other paucibacillary forms react positively tothe intradermal lepromin or Mitsuda test (with dead M. leprae bacilli and a readingafter 28 days), since their cellular immunity is generally not affected. In contrast,lepromatous leprosy and other multibacillary forms give negative results to theMitsuda test. The lepromin test has limited value for detecting infection in those incontact with patients or the general population in an endemic area (Jacobson, 1991).Serological tests are also of limited use.The ELISA technique (Young and Buchanan, 1983) for measuring PGL-1 (phenolicglycolipid antigen) antibodies is a great step forward. The reactive titerdepends on the patient’s bacillary load and also serves to detect infection in thosewho are in contact with multibacillary patients, as well as in some people in endemicareas (Jacobson, 1991). In Malawi, Africa, where most cases are paucibacillary, thetest was not sufficiently sensitive (unless its specificity were to be sacrificed), but it