Canine heartworm disease in Porto Velho: first record, distribution map and occurrence of positive mosquitoes

Abstract

The aim of this study was to make the first report on canine heartworm disease in the state of Rondônia and confirm its transmission in this state. Blood samples were randomly collected from 727 dogs in the city of Porto Velho. The samples were analyzed to search for microfilariae and circulating antigens, using three different techniques: optical microscopy on thick blood smears stained with Giemsa; immunochromatography; and PCR. Mosquitoes were collected inside and outside the homes of all the cases of positive dogs and were tested using PCR to search for DNA of Dirofilaria immitis. Ninety-three blood samples out of 727 (12.8%) were positive according to the immunoassay technique and none according to the thick smear method. Among the 93 positive dogs, 89 (95.7%) were born in Porto Velho. No difference in the frequency of infection was observed between dogs raised indoors and in the yard. PCR on the mosquitoes resulted in only one positive pool. This result shows that the transmission of canine heartworm disease is occurring in the city of Porto Velho and that there is moderate prevalence among the dogs. The techniques of immunochromatography and PCR were more effective for detecting canine heartworm than thick blood smears. The confirmation of canine heartworm disease transmission in Porto Velho places this disease in the ranking for differential diagnosis of pulmonary nodules in humans in Rondônia.Keywords: Canine heartworm disease, Dirofilaria immitis, PCR, immunochromatography, thick blood smears, Brazil. ResumoO objetivo deste estudo foi de registrar pela primeira vez a dirofilariose canina no estado de Rondônia e confirmar sua transmissão neste estado. Amostras de sangue de 727 cães foram colhidas aleatoriamente na cidade de Porto Velho. As amostras foram analisadas em busca de microfilárias e antígenos circulantes usando três técnicas diferentes: microscopia ótica de gota espessa corada com Giemsa e imunocromatografia de fluxo lateral e PCR. Mosquitos foram colhidos no domicilio e peridomicílio de todos os casos de cães positivos, estes mosquitos foram testados pela PCR na detecção de DNA de Dirofilaria immitis. Noventa e três das 727 amostras de sangue foram positivas na técnica de imunoensaio (12,8%). Nenhuma amostra foi positiva na gota espessa. Entre os 93 cães positivos, 89 (95,7%) foram nascidos em Porto Velho. Nenhuma diferença na frequencia de infecção foi observada entre cães criados dentro da casa ou no quintal. O PCR dos mosquitos resultou em apenas um pool positivo. Este resultado mostra que a transmissão de dirofilariose canina está ocorrendo na cidade de Porto Velho e a frequência que ocorre nos cães é considerada moderada. As técnicas de imunocromatografia e PCR são mais eficazes na detecção de dirofilariose comparadas a gota espessa. A confirmação de transmissão de dirofilariose canina em Porto Velho, coloca esta doença no ranking de diagnóstico diferencial de nódulos pulmonares em seres humanos em Rondônia.

Canine Heartworm Disease in a Brazilian Non-Endemic Area

“…Hematological and biochemical alterations observed in these dogs matched with the alterations described by Rocha (2010) and Polizopoulou et al (2000), who observed thrombocytopenia, non-regenerative anemia, leukocytosis by neutrophilia, eosinophilia and basophilia, and increased ALT and creatinine.…”

“…In Brazil, although some studies have reported high frequencies in coastal areas, reports in remote coastal regions are also common (OGAWA et al, 2013;LABARTHE et al, 2014;SOARES et al, 2014). Souza and Larsson (2001) detected 6/154 (3.8%) D. immitis-positive blood samples in São Paulo (capital of the State), and supports the present reports from Botucatu, located 300km from the capital, where the prevalence of the parasite is less than 1% (GUERRA et al, 2000).…”

“…In Brazil, the higher prevalence is associated to the coastal areas (SOARES et al, 2014). However, the disease can be also related to no-coastal areas (OGAWA et al, 2013).…”

Detection of Dirofilaria immitis using microscopic, serological and molecular techniques among dogs in Cabo Frio, RJ, Brazil

“…These findings differed from those reported by Hou et al (2011), Simsek et al (2011) and Bamorovat et al (2017), who observed better results through PCR. Ogawa et al (2013) in Porto Velho, Rondônia, Brazil, showed that 12.8% (93/727) of the dogs that they evaluated were positive according to immunoassay, 0% through the thick smear test and 10% (73/727) through PCR. Borthakur et al (2015) in India obtained better efficiency through PCR (13.93%) than through microscopic parasitological techniques (11.38%), but with lower results than those obtained through ELISA (18.03%).…”

Dirofilaria immitis infection in dogs in Algodoal Island, Brazilian Amazon

“…Humans and felines, which may be accidental hosts, are more susceptible to infection in areas with high prevalence of the canine disease (Garcez et al 2006, Mirahmadi et al 2017, which is distributed all over the globe (Bolio-Gonzalez et al 2007, Bowman & Atkins 2009, Hou et al 2011, Simsek et al 2011, Montoya-Alonso et al 2015, Bendas et al 2017. It has been found in every geographical region of Brazil, with prevalence rates over the last decade ranging from 2.1% in Florianópolis, in the Southern state of Santa Catarina (SC), to 62.2% in Armação de Búzios, in the Southeastern state of Rio de Janeiro (RJ) (Silva et al 2008, Dirofilaria immitis infection in dogs in Algodoal Island, Brazilian Amazon Furtado et al 2009, Ogawa et al 2013, Labarthe et al 2014, Soares et al 2014, Ramos et al 2015.…”