Infection by Mycobacterium leprae of household contacts of lepromatous leprosy patients from a post-elimination leprosy region of Colombia

Abstract

The Leprosy Control Program of Antioquia, (post-elimination leprosy state of Colombia), had registered by 1999, 56 lepromatous leprosy patients and their household contacts (HHC). Our interest was to detect Mycobacterium leprae infection in these HHC. Clinical examination, acid-fast bacillary staining (AFB) in nasal secretions, and slit skin samples, IgM anti-PGL-I in serum and negative. These results are an indication that the transmission of the infection is still happening in a region considered in the post elimination phase. The two new patients represent an infection source for others contacts, and groups 2 and 3 are infected HHC that could develop the disease in future. Follow up of high risk population is necessary to achieve real elimination of leprosy.Key words: post elimination leprosy region -household contact infection -Mycobacterium leprae -ColombiaThe total number of leprosy cases around the world is decreasing; at the beginning of 2003 the total of cases was 534,000 (WHO 2004). The principal factor contributing to this success worldwide has been the implementation of the standardized multiple drug therapy (MDT) regimen against the causative agent Mycobacterium leprae. Leprosy elimination campaigns for case detection in communities, training of physicians and leprosy field workers, and promotion of public awareness are additional key elements in this infectious disease control approach. Actually, WHO has a commitment to "the final push to reach elimination by 2005", a target originally set for 2000 (WHO 2003). However, the opinions of experts in clinical and research field range from optimistic to pessimistic concerning the reach of this target (Naafs 2000, Visschedijk et al. 2000, Lockwood 2002.The apprehension arises from the incomprehensible incidence rate that is still high in six countries (4.19 per 10,000), which represents 88% of the world's new cases detected in 2002, and the insufficiency of consistent in- formation on the core elements of this infectious disease, namely, what is the source, the reservoir and the mode of transmission, and the host factors related to immunity or disease (Reich 1987, Naafs et al. 2001. Additionally, while prevalence has been reduced, since MDT implementation, there has not been a compelling difference in the number of newly detected cases in the same period and population (incidence rates) before and after introduction of MDT (Feenstra 2003).The prevalence of leprosy in Colombia has decreased over the last 15 years. While in 1985, leprosy prevalence was 5,5/10,000, it is now reduced to 0,5/10,000 (www.minsalud.gov.co). The introduction of MDT in Colombia in 1985 has contributed to the decrease in disease burden. According to WHO, leprosy in Colombia is not a public health problem, and control of leprosy is in the "post-elimination phase" (Pinto 2000).Nevertheless, the reduction in prevalence is not a real reflection of the problem with respect to population distribution. For instance, Colombia has some regions where the actual prevalence is 1 to 3/10,000 a...

Survey to identify Mycobacterium leprae-infected household contacts of patients from prevalent regions of leprosy in Colombia

“…This is evident in the variation reported for different geographical populations. The current results show 13.4% (n = 54) of HHC with positive titers for IgM anti-PGL1; other studies have shown frequencies of infected contacts ranging from 13 to 93% (Meeker et al 1986, Amezcua et al 1987, Mora et al 1992, Cardona-Castro et al 2005. Nevertheless, this number of seropositive HHC does not indicate the true frequency of infected individuals in the studied population since some infected persons do not produce specific antibodies (Oskam et al 2003).…”

“…In a similar study designed to detect Mycobacterium leprae infection in HHC in a non-prevalent region of Colombia, we found two HHC with multibacillary leprosy (Cardona-Castro et al 2005). These findings suggest that early diagnosis of leprosy in HHC through clinical examination at the time of index case diagnosis is not sufficient and that continued follow-up and testing using other available diagnostic tools is necessary.…”

Clinical, bacteriological and immunological follow-up of household contacts of leprosy patients from a post-elimination area - Antioquia, Colombia

“…It is important to note that one of the HHC who sero-converted was an 11-year-old girl, which demonstrates the importance of follow-up of M. leprae infection in children for early disease detection and disability prevention in a young population. Other studies have shown frequencies of infected contacts that range from 13-93% (Meeker et al 1986, Amezcua et al 1987, Cardona-Castro et al 2005. Early detection of PB leprosy was possible in one HHC who had a unique lesion and the diagnosis was confirmed by positive nested PCR.…”

“…Therefore, diagnosis is often delayed, contributing to the onset of the disease and allowing transmission and sequelae (Lockwood & Kumar 2004). The use of other tests in addition to periodic evaluations by clinical exam to detect infected HHC, as well as detailing their immune response and bacteriological state, can contribute to the identification of infected HHC and new leprosy cases (Cardona-Castro et al 2005).…”

Use of Protein Microarrays To Define the Humoral Immune Response in Leprosy Patients and Identification of Disease-State-Specific Antigenic Profiles

“…Indeed, studies have shown that contacts of MB leprosy patients have an increased risk of developing leprosy themselves (41). It has also been found that contacts who have an antibody response to the M. lepraespecific phenolic glycolipid (phenolic glycolipid I [PGL-I]) have a much greater chance to develop clinical leprosy than those without an antibody response (3,7,19,23). Yet almost half of those who have antibodies to PGL-I never develop leprosy, and half of those who develop leprosy never have PGL-I antibody.…”