**3. Conclusions**

*2.4.3. Experimental models of congenital transmission*

36 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

in the liver, spleen, and bone marrow of the offspring [63].

In experimental model in which hamsters were infected with 106

**2.5. Other factors related to substance abuse and work environment**

*2.5.1. Drug use*

*2.5.2. Work environment transmission*

In a murine model of visceral leishmaniasis, twenty 12-week -old female BALB/c mice were infected with *L. infantum*. They were mated 8 weeks later with healthy males, and the females were sacrificed at days 13 and 18 of gestation. The offspring were sectioned in half for PCR analysis. In 15 of the 20 pregnant mice, the parasite was detected by PCR in the spleen. In the offspring, 3 of the 88 placentas and 4 of the 88 pups tested positive for *Leishmania* by PCR [75]. In studies to determine vertical transmission of *Leishmania* in beagles, parasitemia was detected

*sis* during the first week of pregnancy, 24 of 93 (25.8%) of the offspring from infected mothers were PCR positive to *Leishmania*, 2 months after the birth [76]. Furthermore, mice infected with high inoculums of *L. mexicana* strain, known as cause of cutaneous leishmaniasis, showed that all female and their placentas were positive to PCR analysis, and revealed that the infection was present in 39 of 110 offspring of infected mothers, also fetal deaths and resorptions were observed [77]. Then is important to be aware to the fact that leishmaniasis could be transmitted transplacentally and causes fetal resorption, death, and reduction in offspring body weight.

In cases of leishmaniasis infection due to fomites, such as sharp, contaminated objects, the most vulnerable population are illicit drug users. In a Spanish study of syringes used for recreational drug use, it was reported that 32-52% of the syringes were contaminated by *Leishmania*, as determined by PCR. Moreover, 3 different genotypes were identified in multiple samples, confirming that the individuals had shared syringes. Therefore, programs that limit the sharing

As described above, *Leishmania* spp. can be transmitted through fluids such as blood and by contact with animals or even contaminated objects. In all cases, there must be an entry route, which is usually a wound. In staffs dedicated to clinical, diagnostic or medical research, it is not uncommon to find reported cases of *Leishmania* infection, although many such likely go unrecognized [80]. Infections due to accidental exposure can be affected by a variety of factors, including kinematics (e.g., the path and characteristics of exposure and the amount of inoculum), parasite characteristics (e.g., pathogenicity, virulence, viability and infective dose) and host characteristics (e.g., immune status, barrier status and actions following the accident) [80]. However, the possibility of infection due to vector exposure in an endemic region should not be ruled out when performing questioning [81]. The first case of work-related leishmaniasis was reported in 1930, and to date, there have been 12 reported cases of *Leishmania* infection due to accidents at work; these have included 6 different *Leishmania* species, with *L. donovani* being implicated in half of the affected individuals. In these cases, the incubation period ranged

of needles should decrease the infection rate among vulnerable individuals [78-79].

parasites/mL of *L. panamen‐*

The *Leishmania* parasite can survive in a wide range of temperatures and pH conditions, which has allowed it to adapt to the diverse conditions encountered within different vector and host species. In recent years, transmission pathways other than those based on vector species have been described, including invasive procedures for therapeutic purposes, sexual practices, pregnancy, drug practices and work-related accidents among health/research staff members, all of which have led to an increase in the number of reported leishmaniasis cases. However, considering that the latency period of the parasite within the host can last up to one year, there are likely more infected individuals than those that have been reported. Because leishmaniasis is not considered to be a disease that can be transmitted between individuals without the intervention of a vector species, laboratory tests for the presence of these parasites to rule out prospective donors are not carried out prior to in most invasive therapeutic procedures. However, in the case of patients with immunodeficiency, the possibility of contracting the disease is significantly increased. Furthermore, during pregnancy, changes to the immune system can allow for the transmission of the parasite from the mother to the fetus. It should also be noted that maternal-fetal infection can also be of sexual origin. Among drug addicts, it was demonstrated that syringe sharing is a significant source of infection. Finally, in addition to populations exposed in endemic areas, staff working in the health or research sectors should also be considered as populations at risk of acquiring this disease.

Taken together, there is a clear need for the health system to reevaluate the global situation concerning leishmaniasis transmission and to implement strategies to reduce the exposure of individuals to *Leishmania* infections.
