Aedes aegypti from temperate regions of South America are highly competent to transmit dengue virus

BACKGROUND

Aedes aegypti is extensively spread throughout South America where it has been responsible for large dengue epidemics during the last decades. Intriguingly, dengue transmission has not been reported in Uruguay and is essentially prevalent in subtropical northern Argentina which borders Uruguay.

METHODS

We assessed vector competence for dengue virus (DENV) of Ae. aegypti populations collected in subtropical Argentina (Corrientes) as well as temperate Uruguay (Salto) and Argentina (Buenos Aires) in 2012 using experimental oral infections with DENV-2. Mosquitoes were incubated at 28 °C and examined at 14 and 21 days p.i. to access viral dissemination and transmission. Batches of the Buenos Aires mosquitoes were also incubated at 15 °C and 20 °C.

RESULTS

Although mosquitoes from temperate Uruguay and Argentina were competent to transmit DENV, those from subtropical Argentina were more susceptible, displaying the highest virus titters in the head and presenting the highest dissemination of infection and transmission efficiency rates when incubated at 28 °C. Interestingly, infectious viral particles could be detected in saliva of mosquitoes from Buenos Aires exposed to 15 °C and 20 °C.

CONCLUSIONS

There is a potential risk of establishing DENV transmission in Uruguay and for the spread of dengue outbreaks to other parts of subtropical and temperate Argentina, notably during spring and summer periods.

Epidemiology of dog bites to people in Uruguay (2010-2020)

BACKGROUND

Dog bites to people are a serious public health problem. Limited information exists at the country level in Latin America. The COVID-19 pandemic changed people's lifestyles and their relationship with pets, and this could potentially affect the incidence of dog bites injuries.

OBJECTIVE

The main objectives of our study were to determine the prevalence of dog-bite injuries in Uruguay from 2010 to 2020 and to compare the prevalence in 2020 to that of pre-pandemic years.

METHODS

Cross-sectional study. Dog-bite notifications for the 2010 and 2020 period were analysed using data from the Uruguayan Ministry of Public Health.

RESULTS

The annual dog-bite injury rate for the 2010-2020 period was 87.51 per 100,000 people. The frequency of bites varied with the victims' sex, with males accounting for 51.8% of the bites (p < 0.0001), and with age, with a higher frequency of bites in the ≤14 years old age group (p < 0.01). The frequency of dog bites was also higher in spring and summer than in autumn (p < 0.0001). There was no statistical difference in the frequency of dog-bite injuries when comparing 2020 with the pre-COVID-19 pandemic years.

CONCLUSIONS

In Uruguay, the frequency of dog-bite injuries varied with season and with the age and sex of the victim. In the first year of the COVID-19 pandemic, the number of people bitten by dogs was no different than that of previous years. This is the first study in Latin America to report national rather than regional data and to include all age groups.

Genetic variability highlights the invasion route of the Lutzomyia longipalpis complex, the main vector of Visceral Leishmaniasis in Uruguay

In the Americas, the sandfly Lutzomyia longipalpis is the main vector of the parasitic protozoa Leishmania infantum, the etiological agent of visceral leishmaniasis (VL). The Lu. longipalpis species complex is currently discontinuously distributed across the Neotropical region, from Mexico to the north of Argentina and Uruguay. During its continental spreading, it must have adapted to several biomes and temperature amplitudes, when founder events should have contributed to the high genetic divergence and geographical structure currently observed, reinforcing the speciation process. The first report of Lu. longipalpis in Uruguay was in 2010, calling the attention of Public Health authorities. Five years later, the parasite Le. infantum was recorded and in 2015 the first case of VL in canids was reported. Hitherto seven human cases by VL have been reported in Uruguay. Here, we publish the first DNA sequences from the mitochondrial genes ND4 and CYTB of Lu. longipalpis collected in Uruguay, and we used these molecular markers to investigate their genetic variability and population structure. We described four new ND4 haplotypes in a total of 98 (4/98) and one CYTB in a total of 77 (1/77). As expected, we were able to establish that the Lu. longipalpis collected in two localities (i.e. Salto and Bella Unión) from the north of Uruguay are closely related to the populations from neighbouring countries. We also propose that the possible route for the vector arrival to the region may have been through vegetation and forest corridors of the Uruguay River system, as well as it may have benefited from landscape modifications generated by commercial forestation. The ecological-scale processes shaping Lu. longipalpis populations, the identification of genetically homogeneous groups and the gene flow among them must be carefully investigated by using highly sensible molecular markers (i.e. genome wide SNPs) since it will help to the understanding of VL transmission and contribute to the planification of public policies on its control.

Epidemiology of cat bites to people in Uruguay: Effects of the age and sex of the victim, season of the year, and the COVID-19 pandemic

Background

Cat bites to people are an important public health problem. However, very little information exists on the epidemiology of people bitten by cats at the level of an entire country in Latin America. Additionally, the COVID-19 pandemic significantly influenced people's lives and their relationships with pets, which could potentially affect the frequency of people bitten by cats.

Aim

The aim of this study was to determine the prevalence of people bitten by cats in Uruguay (2010 to 2020) according to the sex and age of the victim, season of the year, and to compare the prevalence in the pandemic year (2020) with that of the pre-pandemic years (2010-2019).

Methods

Cross-sectional study. Cat-bite notifications for the 2010-2020 period were analyzed using data from the Uruguayan Ministry of Public Health (Uruguay).

Results

The annual cat-bite rate for the 2010-2020 period was 2.1 per 100,000 people. The frequency of cat bites varied with the victim´s sex (p < 0.0001), being greater in females (n = 506, 66.5%) than in males (n = 255, 33.5%). The age at being bitten by cats varied with the sex of the victim, with males being bitten at an earlier age than females (p < 0.0001). Among the age categories of 30-74 years, females were bitten more than males (p < 0.05). Overall, cat bites were much less frequent in the oldest age categories (over 75 years old, p < 0.05). The percentage of cat bites tended to change with the season of the year (p = 0.08), with most bites occurring in spring and summer. The frequency of cat-bite injuries was similar between 2020 and the pre-COVID-19 pandemic years.

Conclusion

In Uruguay, cat bite incidents were affected by the victim's sex (more in females) and age, as well as by the season. During the initial year of the COVID-19 pandemic, the rate of cat bites was no different from those in earlier years.