ABSTRACT

Lutzomyia longipalpis (Lutz & Neiva, 1912) constitutes the most epidemiologically relevant vector of visceral leishmaniasis (VL) in the New World. On October 25, 2023, the Macapá Center for Strategic Information in Health Surveillance registered a case of VL in the Km9 neighborhood, in Macapá. This study aimed to describe the Phlebotominae species in this area to assist the confirmation of the autochthony of the case. In total, 12 specimens were collected, of which five belonged to the Lutzomyia longipalpis species, confirming the presence of the VL agent vector and the possible autochthony of the transmission.

DESCRIPTORS:
Leishmaniose Visceral; Vector; Entomological Surveillance

INTRODUCTION

The Phlebotominae subfamily belongs to the Psychodidae family and currently consists of about 1,060 described species worldwide ¹1. Galati EAB, Rodrigues BL. A review of historical Phlebotominae taxonomy (Diptera: Psychodidae). Neotrop Entomol. 2023;52(4):539–59. https://doi.org/10.1007/s13744-023-01030-8
https://doi.org/10.1007/s13744-023-01030... , including Lutzomyia longipalpis (Lutz & Neiva, 1912), the most epidemiologically relevant vector of visceral leishmaniasis (VL) agent in the New World ²2. Gontijo CMF, Melo MN. Leishmaniose visceral no Brasil: quadro atual, desafios e perspectivas. Rev Bras Epidemiol. 2004;7(3):338–49. https://doi.org/10.1590/S1415-790X2004000300011
https://doi.org/10.1590/S1415-790X200400... . It is widely present (from Mexico to Argentina), and it has been identified in all states in the Amazon region, except for the state of Amazonas ³3. Galati EAB. Phlebotominae (Diptera, Psychodidae): classification, morphology and terminology of adults and identification of American taxa. In: Rangel E, Shaw J, editores. Brazilian Sand Flies: Biology, Taxonomy, Medical Importance and Control. Cham: Springer International Publishing AG; 2018. .

The zoonotic form of VL, caused by the protozoan Leishmania (Leishmania) infantum chagasi , has dogs as its main reservoir. This severe disease mainly affects children and older adults and causes high lethality in the absence of timely and adequate treatment ⁴4. Galvis Ovallos F, Silva RA, Silva VGd, Sábio PB, Galati EAB. Leishmanioses no Brasil: aspectos epidemiológicos, desafios e perspectivas. In: Meneguetti DUO, Oliveira J, Camargo LMA, organizadores. Atualidades em medicina tropical no Brasil: protozoários. Rio Branco: Stricto Sensu; 2020. .

VL is currently spreading throughout Brazil, associated with factors such as urbanization, mobility of infected dogs, and especially vector dispersion ⁴4. Galvis Ovallos F, Silva RA, Silva VGd, Sábio PB, Galati EAB. Leishmanioses no Brasil: aspectos epidemiológicos, desafios e perspectivas. In: Meneguetti DUO, Oliveira J, Camargo LMA, organizadores. Atualidades em medicina tropical no Brasil: protozoários. Rio Branco: Stricto Sensu; 2020. . Cases of VL have been identified in 25 of the 26 states of the Brazilian Federation. However, in some regions, transmission is associated with other species of Phlebotominae, which are considered secondary vectors ⁴4. Galvis Ovallos F, Silva RA, Silva VGd, Sábio PB, Galati EAB. Leishmanioses no Brasil: aspectos epidemiológicos, desafios e perspectivas. In: Meneguetti DUO, Oliveira J, Camargo LMA, organizadores. Atualidades em medicina tropical no Brasil: protozoários. Rio Branco: Stricto Sensu; 2020. . The occurrence of VL has been reported in areas further east and north from the Amazon biome in Brazil, generating a debate on whether it is an enzootic disease to the region or if it has been introduced by infected migrant dogs ⁵5. Confalonieri UEC, Margonari C, Quintão AF. Environmental change and the dynamics of parasitic diseases in the Amazon. Acta Tropica. 2014;129:33–41. https://doi.org/10.1016/j.actatropica.2013.09.013
https://doi.org/10.1016/j.actatropica.20... .

The municipality of Macapá was considered an area without VL transmission up to 2017, when autochthonous canine cases were reported ⁶6. Pessoa LMB, Pinto EHC, Chaves TES, Rabelo GS, Brito AL, Zanini VM, et al. Phlebotomine sand flies (Psychodidae: Phlebotominae) in an area of canine infection caused by Leishmania infantum in the state of Amapá, eastern Amazon. Rev Bras Parasitol Vet. 2023;32(3):e002423. https://doi.org/10.1590/S1984-29612023054
https://doi.org/10.1590/S1984-2961202305... . Canine cases preceded human cases, depending on the presence of competent vectors in the transmission area. Despite the risk of establishing an urban cycle of transmission of this infection, few studies have been carried out on the Phlebotominae fauna in this municipality, failing to detect Lu. longipalpis ⁶6. Pessoa LMB, Pinto EHC, Chaves TES, Rabelo GS, Brito AL, Zanini VM, et al. Phlebotomine sand flies (Psychodidae: Phlebotominae) in an area of canine infection caused by Leishmania infantum in the state of Amapá, eastern Amazon. Rev Bras Parasitol Vet. 2023;32(3):e002423. https://doi.org/10.1590/S1984-29612023054
https://doi.org/10.1590/S1984-2961202305... , ⁷7. Cavalcante KS, Rodrigues Júnior J, Gama GS, Santos WM, Galardo AKR. Flebotomíneos (Diptera: Psychodidae) em uma área periurbana na cidade de Macapá, Amapá, Brasil. Braz J Animal Environ Res. 2021;4(2):2417–26. https://doi.org/10.34188/bjaerv4n2-070
https://doi.org/10.34188/bjaerv4n2-070... .

On October 25, 2023, the Macapá Center for Strategic Information in Health Surveillance confirmed a case of VL in a 51-year-old patient who resided in the Km9 neighborhood in the aforementioned municipality. This study carried out an entomological investigation to detect Phlebotominae and assist in the confirmation of the autochthony of the case, the results of which are described below.

METHODS

An entomological research was conducted in the Km9 neighborhood, a peripheral area of Macapá. About 300 meters from the patient’s residence, a home shelter for about 150 dogs. The captures were carried out in the peridomicile of this property (00°03’47.82”N, 51°08’12.94”W) ( Figure ). In total, three points were selected (on both sides and at the back of the land in which the dog shelter is located) for the installation of a CDC-type light trap. The captures were carried out for three consecutive days, from November 1 to 3, 2023, totaling 108 hours of sampling.

The collected Phlebotominae were taken to the Medical Entomology Laboratory at the Instituto de Pesquisas Científicas e Tecnológicas do Amapá (IEPA – Institute of Scientific and Technological Research of Amapá) for sex screening and taxonomic identification following Galati ³3. Galati EAB. Phlebotominae (Diptera, Psychodidae): classification, morphology and terminology of adults and identification of American taxa. In: Rangel E, Shaw J, editores. Brazilian Sand Flies: Biology, Taxonomy, Medical Importance and Control. Cham: Springer International Publishing AG; 2018. . All collected specimens were deposited in the IEPA zoological collection, with their respective registration numbers.

RESULTS AND DISCUSSION

In the three days of capture, 12 Phlebotominae individuals belonging to six species were collected in the peridomicile, namely: Lu. longipalpis (n = 5), Nyssomyia antunesi (Coutinho, 1939) (n = 3), Micropygomyia (Sauromyia) rorotaensis (Floch & Abonnenc, 1944) (n = 1), Psychodopygus squamiventris maripaensis (Floch & Abonnenc, 1946) (n = 1), Psychodopygus ayrozai (Barretto & Coutinho, 1940) (n = 1), and Evandromyia (Evandromyia) brachyphalla (Mangabeira, 1941) (n = 1) ( Table ).

Of the 12 collected specimens, five belonged to the Lu. longipalpis species, confirming the presence of the main vector for VL in Macapá and the local transmission of the disease.

The failure of previous entomological research to find Lu. longipalpis in the municipality ⁶6. Pessoa LMB, Pinto EHC, Chaves TES, Rabelo GS, Brito AL, Zanini VM, et al. Phlebotomine sand flies (Psychodidae: Phlebotominae) in an area of canine infection caused by Leishmania infantum in the state of Amapá, eastern Amazon. Rev Bras Parasitol Vet. 2023;32(3):e002423. https://doi.org/10.1590/S1984-29612023054
https://doi.org/10.1590/S1984-2961202305... ^{, 7}7. Cavalcante KS, Rodrigues Júnior J, Gama GS, Santos WM, Galardo AKR. Flebotomíneos (Diptera: Psychodidae) em uma área periurbana na cidade de Macapá, Amapá, Brasil. Braz J Animal Environ Res. 2021;4(2):2417–26. https://doi.org/10.34188/bjaerv4n2-070
https://doi.org/10.34188/bjaerv4n2-070... may be related to a recent introduction of the species in the area or to its low density, which hinders detection. However, it is worth mentioning the occurrence of Lu. longipalpis had been registered in Ferreira Gomes, a municipality 137 km from Macapá ²⁰¹³8. Galardo AKR, Galardo CD, Santana AA, Mendes JCC, Souza FRA, Duarte JP, et al. Primeira ocorrência de Lutzomyia (Lutzomyia) longipalpis Lutz & Neiva, 1912 (Diptera: Psychodidae: Phlebotominae) no Estado do Amapá, Brasil. Biota Amazônia. 2013;3(2):179–83. http://doi.org/10.13140/2.1.3090.4001
http://doi.org/10.13140/2.1.3090.4001... .

Although the occurrence of canine leishmaniasis has been reported in Macapá, the detection of a human case combined with the finding of the vector Lu. longipalpis in the urban area of the municipality calls for a wider awareness within health services to aid surveillance, the early diagnosis of human cases, and its timely treatment, as well as requiring measurements towards understanding the risk of infection for the human and canine population and the implementation of VL control measures.

Vector identification configures a key element to define case autochthony and suggests the need to monitor Lu. longipalpis by entomological surveillance activities in other locations in Macapá.

References

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