Short report: ITS-1 DNA sequence confirmation of Leishmania major as a cause of cutaneous leishmaniasis from an outbreak focus in the Ho district, southeastern Ghana.

Abstract

We report first-time definitive evidence of human cutaneous leishmaniasis (CL) resulting from L. major infections in Ghana. The evidence is in the form of PCR testing and DNA sequence analysis of skin sample biopsies from residents of the Ho District in the forested Volta Region of southeastern Ghana (Figure 1). The moist semi-deciduous forest of this region of Ghana is atypical for CL. Although two sand fly species with known or suspected potential to transmit L. major were present in communities where human cases of CL originated, they were found in such small numbers that their role in the transmission of CL is uncertain. Twelve million people worldwide are believed to be infected with the parasites that cause leishmaniasis, and 88 different nations report this disease. 1 It is estimated that up to 75% of the 1.5 million new cases of leishmaniasis that occur each year are CL with L. major the responsible etiologic agent of this cutaneous disease in Africa and throughout Eurasia. Over this vast range, CL transmission is typically associated with arid desert and savannah conditions where the parasites are harbored in rodents and vectored by night-biting sand flies of the genus Phlebotomus. For many years, leishmaniasis in Africa and Western Asia has been grossly underestimated; it now appears that the disease is much more prevalent than previously suspected. 1 In Ghana, CL was considered a parasitic disease risk that was limited to the arid sahel-savannah region in the north, but no infections or evidence of transmission had been actually described. Thousands of man-hours of mosquito surveillance have been conducted in northern Ghana 2 for the purpose of quantifying man-biting malaria vectors, but there is no record or report of sand flies in these collections. However, since 1999, an increasing number of suspected CL cases have been reported from the southern Volta Region of Ghana in a moist forest ecosystem where such skin lesions had not been previously reported. The assumption of CL was based subjectively on local microscopy, which identified Leishmania amastigotes in skin lesion biopsies taken from a cluster of local patients. Between 1999 and 2002, the Ghana Health Service recorded 2,426 suspected cases of CL in the Ho, Hohoe, and Kpando Districts (2,348, 2, and 76 cases, respectively). In 2003, the number of suspected cases rose to 6,450 (6,185, 174, and 91 in the same respective districts) with 116 villages affected (Ghana Ministry of Health (MoH), Annual Report, 2003). A limited survey of towns in the Ho district during 2002 identified suspected CL lesions in 12.2–32.3% of local school children. In an effort to determine the cause and extent of the outbreak, the Ghana MoH initiated an epidemiologic study in Ho district with assistance from the U.S. Naval Medical Research Unit No. 3 and the Noguchi Memorial Institute of Medical Research. Initial efforts of our study intended to verify the presence of Leishmania parasites by applying newly developed PCR methods to 5 previously collected, archived biopsy samples