Enzootic Angiostrongyliasis, Guangdong, China, 2008–2009

To the Editor: The nematode Angiostrongylus cantonensis was discovered in pulmonary arteries and hearts of domestic rats in Guangzhou (Canton), China, by Chen in 1935 (1). This parasite has a complex life cycle (2) and causes cerebral angiostrongyliasis after ingestion of infective larvae found in freshwater and terrestrial snails and slugs, paratenic hosts (such as freshwater fish, shrimp, frogs, and crabs), and contaminated vegetables (3). 
 
During 2000–2006, a total of 7 outbreaks of angiostrongyliasis were reported in the People’s Republic of China, including an outbreak in Zhaoqing, Guangdong Province (4–6). We conducted a survey of A. cantonensis nematodes in mollusks and rodents in Qingyuan, Guangong Province, during August 2008–October 2009. 
 
Qingyuan is located in northern Guangdong Province (23°31′–25°12′N, 111°55′–113°55′E). It is the largest city in the province. Qingyuan borders Zhaoqing on the west and Guangzhou on the south. Its climate is subtropical monsoon, and it has an average annual temperature of 20.7°C. The city has an area of 19,152.89 km2 and a population of 3.87 million. Nematode hosts were obtained in 3 counties in Qingyuan: Qingxin, Fogang, and Lianzhou. 
 
During August 2008–October 2009, we captured 288 rats of 7 species (257 Rattus norvegicus, 13 R. flavipectus, 7 R. losea; 6 R. rattus, 3 Bandicota indica, 1 R. rattus alexandrinus, and 1 Mus musculus). Rats were examined for adult A. cantonensis nematodes in pulmonary arteries and right heart cavities. 
 
Among the 288 rats examined, 27 (9.4%) from 3 species were infected with A. cantonensis adults in their cardiopulmonary systems (Table). Infected rodents were found in all 3 counties. The 27 infected rats were 25 R. norvegicus, 1 R. losea, and 1 M. musculus. R. norvegicus rats were most frequently captured in the 3 counties, and this rodent had the highest prevalence of infection. Infected B. indica rats in Lianzhou and M. musculus rats in Qingxin were also found, but the total numbers of infected animals and the prevalences are lower than that for R. norvegicus rats. On the basis of these findings, we conclude that R. norvegicus rats are the major definitive host for A. cantonensis nematodes in Qingyuan. 
 
 
 
Table 
 
Prevalence of infection with Angiostrongylus cantonensis in 3 snail species and rodents in 3 counties in Qingyuan, Guangdong Province, China, 2008–2009 
 
 
 
Specimens from 510 snails (144 Pomacea canaliculata, 306 Achatina fulica, and 60 Bradybaena despecta) were digested with pepsin for isolation of A. cantonensis larvae (7). Metastrongylid larvae were found in 21 (4.1%) of 510 examined snails. Prevalence rates of A. cantonensis in P. canaliculata, A. fulica, and B. despecta were 8.3%, 2.0% and 5.0%, respectively. Differences between the 3 prevalence rates were significant (χ2 9.604, p<0.05). Prevalence rates in the 3 counties are shown in the Table. 
 
All 3 species of infected snails were found in Qingxin and Fogan Counties. P. canaliculata and B. despecta snails were found infected in Qingxin County. However, only A. fulica snails were found infected in Fogang. These findings are similar to those of studies conducted in Guangdong Province (8–10). 
 
Distributions of snail species among the 3 sites differed. Although all 3 species were found in Qingxin and Fogang Counties, only A. fulica snails were found in Lianzhou County. Lower temperatures in this county may contribute to this uneven distribution. Our failure to detect infected snail hosts in Lianzhou County was unexpected, and further surveys are needed to identify parasite hosts in this area. Our findings suggest that the 3 species may play a major role as intermediate hosts for A. cantonensis nematodes in human infections. 
 
Qingyuan is a natural focus for A. cantonensis nematodes. Residents in the study area frequently eat raw or undercooked snails and slugs, unaware that these animals may contain infective larvae of A. cantonensis that can cause eosinophilic meningitis. Therefore, to protect local residents from parasite infections, inhabitants of this region must be given relevant information about A. cantonensis nematodes. Control measures to control spread of this parasite must also be implemented.

To the Editor: The nematode Angiostrongylus cantonensis was discovered in pulmonary arteries and hearts of domestic rats in Guangzhou (Canton), China, by Chen in 1935 (1). This parasite has a complex life cycle (2) and causes cerebral angiostrongyliasis after ingestion of infective larvae found in freshwater and terrestrial snails and slugs, paratenic hosts (such as freshwater fi sh, shrimp, frogs, and crabs), and contaminated vegetables (3).
During 2000-2006, a total of 7 outbreaks of angiostrongyliasis were reported in the People's Republic of China, including an outbreak in Zhaoqing, Guangdong Province (4)(5)(6) Among the 288 rats examined, 27 (9.4%) from 3 species were infected with A. cantonensis adults in their cardiopulmonary systems (Table). Infected rodents were found in all 3 counties. The 27 infected rats were 25 R. norvegicus, 1 R. losea, and 1 M. musculus. R. norvegicus rats were most frequently captured in the 3 counties, and this rodent had the highest prevalence of infection. Infected B. indica rats in Lianzhou and M. musculus rats in Qingxin were also found, but the total numbers of infected animals and the prevalences are lower than that for R. norvegicus rats. On the basis of these fi ndings, we conclude that R. norvegicus rats are the major defi nitive host for A. cantonensis nematodes in Qingyuan.
Distributions of snail species among the 3 sites differed. Although all 3 species were found in Qingxin and Fogang Counties, only A. fulica snails were found in Lianzhou County. Lower temperatures in this county may contribute to this uneven distribution. Our failure to detect infected snail hosts in Lianzhou County was unexpected, and further surveys are needed to identify parasite hosts in this area. Our fi ndings suggest that the 3 species may play a major role as intermediate hosts for A. cantonensis nematodes in human infections.
Qingyuan is a natural focus for A. cantonensis nematodes. Residents in the study area frequently eat raw or undercooked snails and slugs, unaware that these animals may contain infective larvae of A. cantonensis that can cause eosinophilic meningitis. Therefore, to protect local residents from parasite infections, inhabitants of this region must be given relevant information about A. cantonensis nematodes. Control measures to control spread of this parasite must also be implemented. Malaria, Oromia Regional State, Ethiopia,

2001-2006
To the Editor: In Ethiopia, malaria is unstable and commonly occurs as intraannual and interannual epidemics. Transmission is associated with altitude, temperature, and rainfall, generally peaking twice a year, after the 2 rainy seasons (March-May and July-September) (1). Cases are caused by Plasmodium falciparum and P. vivax. Anopheles arabiensis mosquitoes are the main vector for both species. Although malaria is the most common communicable disease in Ethiopia (2), few longitudinal case data has been published (3).
We report a retrospective analysis of outpatient data for July 2001-June 2006 obtained from all secondary and tertiary government-run health facilities (152 health centers and 25 hospitals) in Oromia Regional State. Oromia has 17 administrative zones and 297 districts. Data were reported monthly on paper forms by health facility staff at district level to the Oromia Regional Health Bureau Zonal Health Offi ces, which aggregated zonal data before forwarding them to the Oromia Regional Health Bureau Malaria Control Department.
Data obtained included number of outpatient cases (i.e., patients attending the health facility grouped by age <5 years and age >5 years); number of clinical malaria cases (i.e., patients with fever grouped by age and sex); number of clinical cases confi rmed by microscopy; and number of cases caused by P. falciparum and P. vivax. If no outpatient data were reported, the case number was changed from zero to missing.