The Chagasic Endemic Situation in Peru

Juan Geny Cornejo del Carpio

Coordinating Doctor of Metaxenic Disease in the area of health for Arequipa
Peru

Summary
The Epidemiological situation of the Chagas disease in Peru, is mainly limited to the Provinces in the South Western region, where the only existing vector is the Triatoma infestans strictly domiciliary. There is another area in the North Eastern area of the country with other species of the triatomic vectors. There is vectorial transmission, but there is little known about its magnitud. Within the Southern Region 80% of the problem is located in the Arequipa Province which is in the Department of the same name, where one can find unique occurrences such as the "Urbanization of the vector". Sillar, a product of volcanic origin which is a construction material for houses and an important component in the Triatoma infestans habitat. The presence of this insect at sea level and above 3,000 meters, active vectorial transmisión, intermediate and final phases of the disease, budgetary difficulties in the elimination of the vector due to the magnitude of its dispersion. Notwithstanding the departments of Tacna and Ica are in a phase of watchfulness as are a few smaller towns in the departments of Arequipa and Moquega.

Epidemiological Situation
The Chagas disease in Peru is spread throughout the south western area on the Pacific called the Greater Southern Region of Peru.

It is divided into departments. They are Ica, Arequipa, Moquegua, Tacna (See situation of the Chagas Endemia, Map of Peru), and in the mountains the departments of Ayacucho with two districts and Apurimac with eight districts. The disease covers an area of 120,372 Km2. The approximate population there is 2,176,620; 109,901 residences are infested throughout the 18 provinces, 85 districts, 580 localities and 582,556 inhabitants directly exposed to the bothers and risks of the triatomines. The only existing species of triatominea in this area is the Triatoma infestans. It lives in homes and is found between 13.0 to 19.0 degrees latitude south and 10 at 3,075 meters above sea level [1].

Tabla 1

Figura 1


Another area which is the department of Cajamarca is in the north eastern, central zone of the Andes between 5 to 6 degrees latitude north, 77.0 to 78.0 longitude and 400 to 1,000 meters above sea level. Amazonas, San Martín and Ucayali; where the thriving of the disease is related to the presence of the species Panstrongylus herreri [1], P. Chinai and Rhodnius ecuadoriensis.

The biggest problem is found in the Greater Southwestern Region, where Arequipa is the department most affected, as we can observe in the following data:

Triatominic Entomological data of the Greater Southern Region of Peru:

Department of Arequipa:
- Index of Infestation Domicile (IID): 0-100%
- Ind. Infection Trypano-Triatomino (ITT): 0-30%

Department of Moquegua: IID 20.16 %

Department of Tacna
- Basal Indexes: IID 8.00% e ITT 3.20%
- Year 2001: IID < 3.00% and ITT 0.00%

Departament of Ica: IID 3.34%

The department of Arequipa has 8 provinces of which 7 are infested. Islay province is not infested and Arequipa province has 80% of homes infested. Castilla province is the second most affected, followed by La Union which in spite of having high infestation indexes, the ITT is negative. In what are called the districts of the Province of Caylloma and Caraveli the IID is higher especially in Caravelí which is higher than 50%, but which is diluted in the average of the 4 districts of the province [2]. In Camaná province triatoma infestans has been detected practically at sea level in Camana's downtown area and in the surrounding neighborhoods [6], In the Lluta districts of Caylloma it has been found behind paintings, wallpaper, in guinea pig cages and chicken pens at 3,075 masl. [7] Notice the following graphs with entomological data:



In the city of Arequipa one observes the fenomenon that Dr. Eleazar Córdova Benzaquen, Biologist from the Medical dept. at the University of San Agustin of Arequipa has called the Urbanization of the Vector which consists of the progressive transfer of the triatoma infestans from the valleys to the cities. It is first colonized by human settlements from the outer city area. There one finds high indexes IID and ITT, being the most critical settlements, located in Tiabaya and Hunter districts, like Santa Rita of Tiabaya with an IID of 92.9% and San Pedro of Tiabaya with an ITT of 20.2% [2]. Notice the following graph of the localities most affected in the outer area of the city of Arequipa and the nearby valleys [2]:


The city of Arequipa, sits at a height of 2,335 masl. Its homes are built from different material. The main one being the white volcanic rock Sillar. It is cut into blocks. These are then used to build the walls. They are placed one on top of the other with or without a poor quality cement to keep them together. This material provides an ideal microclimate for the insect in the city, where temperatures vary between 10 and 22 degrees Celsius (see photos 01,02,03 and 04). In the following Graphs we can observe that the predominant material in the human settlements in the outer areas of town are of sillar with corrugated plastic roofs and brick with cement. The highest percentages of triatominic infestation correspond to the first two followed by adobe with corrugated metal roofs (see photo No. 04). In graph no 12 the bedrooms, the sheep and rabbit pens are the most infested. The rabbit pens have the highest ITT, which is also significant in the sheep pens and sleeping quarters [4]:



Photo 1: Typical homes in the outer urban areas of Arequipa, infested with Triatoma infestans. Photo: J. Cornejo


Photo 2: Home in the outer city area built with Sillar and highly infested with triatominic and 5 children live here. Photo: J. Cornejo

Photo 3: Home and view from behind showing all of the nymphalid stages of the T. infestans. Photo: J. Cornejo

Photo 4: Home in a rural area built with rocks, adobe and straw roof with domestic animals and triatominos inside


Morbidity
The human seroprevalence is 0.7 al 12% [1], and is estimated at 73 894 of the human cases in the greater southern region of Peru [3]. Among school children in Vitor Valley 11.3% seropositives were found at the same time serological ELISA-IFI and 12.9% of these are xenodiagnosed positive [5]; being found in the asymtomatic phase of the Chagas disease, they are being administered benznidazol; their homes and surroundings have been treated with the insecticide piretroide which has a residual action.

With children under 5 years old in Alto San Jose of Tiabaya 6.25% are seropositive and serologic ELISA-IFI [8] and have followed the same treatment as those before.

In the general population in serologic sifting with the ELISA Chagas test, a Reactivity Index of 9.4% was found in Santa Rita of Tiabaya, 5.07% in San José of Tiabaya and 1.27% in Santa Teresa of Tiabaya [Regional malaria program report and OEM, 1998].

During the last 8 years severe cases were reported in the districts of Hunter, Tiabaya, Cayma, Miraflores, Quequeña, Bustamante, all of them are districts in the Province of Arequipa.

As the serologic checks continue more cases are being found among those under 15 years old having Chagas asymptomatic, in Andamayo-Castilla, in Uchumayo, San José of Tiabaya, reported cases in the last epidemiological weeks.

In blood banks the seroprevalence of human infection was 3.17% for Arequipa in 2001 [Regional Report for INCOSUR, Arequipa, 2001]; The seroprevalence in the greater part of the region among blood banks was1,59% in 2000 [9].

Vectorial Control
The budgets for the vectorial control are the smallest and in spite of having made an overall Plan for the entire Region with an attack phase set for 1999-2001, advances were only made in the departments of Tacna and Ica which presently are being checked. The departments of Arequipa and Moquegua haven't had more advances. In Arequipa they fumigated 5.63% of all of the homes, keeping check of 48 small localities. A new overall Regional plan has been made for the next 5 years whose cost reaches 7,407,500 million dollars U.S. hoping that the effort of our authorities with international support could finance it to free our towns and cities of this terrible calamity.

We hope to achieve in the near future the Elimination of the Triatoma infestans in our regions so our children and young people can live with the confidence of a peaceful night and a new and enthusiastic dawn.

References

1. Ministry of health of Perú, Dirección General de Salud a las Personas, Dirección del Programa de Control de Enfermedades Transmisibles - Control de Malaria y Otras Enfermedades Metaxénicas,1998. "Doctrina Normas y Procedimientos para el Control de la Tripanosomiasis o Enfermedad de Chagas en el Perú".
2. Region of health of Arequipa, Dirección Ejecutiva de Salud a las Personas, Dirección de Salud Integral; Área de Prevención y Control de Riesgos y Daños, 2002. "Plan Operativo Regional del componente de Enfermedades Metaxénicas".
3. Region of health of Arequipa, Dirección Ejecutiva de Salud a las Personas, Dirección de Salud Integral; Área de Prevención y Control de Riesgos y Daños, 2002 "Plan Macro Regional de Eliminación del Triatoma infestans e Interrupción de la Transmisión transfusional del T. cruzi".
4. Cornejo, J. , Córdova B. E. y Sisniegas D. W. 1994. "Control de T. Infestans mediante limpieza y mejoramiento de la vivienda en tres sectores de la ciudad de Arequipa . Inf. MINSA-RS. Arequipa"
5. Mendoza T. A.; Córdova B. E. ; Vásquez H. L. ; Velásquez T. R. Ruelas N.; Ancca J .M. 2001. Seroprevalencia de Infección por Trypanosoma Cruzi en Escolares del Valle de Vítor, Arequipa, Perú.
6. Cornejo, J.; Córdova B. E.; Mendoza T. A.; Linares H. O.; Valdivia O. A. 2002. "Investigación Epidemiológica de Chagas en tres distritos de la Provincia de Camaná-Arequipa"
7. ZONADIS Arequipa, Programa de Control de Malaria y OEM, Cornejo, J., 1998. "Informe de Investigación epidemiológica sobre caso sospechoso de enf. de Chagas y presencia del triatoma infestans en el distrito de Lluta, provincia de Caylloma, Arequipa.
8. Region of health of Arequipa, Dirección Ejecutiva de Salud a las Personas, Dirección de Salud Integral; Área de Prevención y Control de Riesgos y Daños, 2001. Notificación del Laboratorio Referencial de Sero reactivos a ELISA e IFI Chagas en encuesta serológica a menores de 5 años en Alto San José de Tiabaya, Arequipa.
9. Ministry of health of Perú, Dirección General de Salud a las Personas, Dirección del programa de Control de Enfermedades Transmisibles - Control de Malaria y Otras Enfermedades Metaxénicas, X Reunión de la Comisión de INCOSUR para la eliminación del T. infestans y la Interrupción Transfusional de la Tripanosomiasis Ameri
cana, 2000. "Informe Técnico Control de la Enfermedad de Chagas en el Perú"

Supplements

Photo 5: Central Plaza Downtown Arequipa The White City - Peru

Photo 6: School children in Vitor Valley with serology for Chagas: Elisa-IFI reactive to those that take the exam of xenodiagnostic.

Photo 7: Choco Mothers Club, Province Of Castilla

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Updating: 11/28/2003